Evaporator Handbook
CONTENTS
Introduction..........................................3 Evaporators..........................................4 Evaporator Tpe Selection......................20 Conguration Congurationss For Energ Conservation Conservation...... . 24 Residence Time In Film Evaporation..........28 Desig De signin ning g For For Energ Energ E Eci cienc enc... . . . . . . . . . . . . 32 Phsical cal Pro Propert erties... .. .. .. .. .. .. .. .. .. .. .. .. .. .. 34 Mechanical Vapor Reco Recomp mpre ress ssio ionn Evap Evapor orat ator ors. s... . .. . . .. . .. . . .. . .. 36 Evaporators For Industrial And Chemical Applications..........................42 Waste Water Evaporators......................47 Evaporator Co Contro ntroll... .. .. .. .. .. .. .. .. .. .. .. .. .. .. 50 Preassembled Evaporators.....................52 The Production O High High Qualit Qualit Juic Juicee Con Concen centr trat ates es... ... . . . . . . . . . . . 53 Engin nginee eeri ring ng Conv Conver ersi sion on........ .. .. .. .. .. .. .. .. .. .. 58 Properties O Saturated Stea Steam m Tem Tempe pera ratu ture re Tab Table les. s.... ... .. . . .. . .. . . .. . . .. . 59
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Introduction As one o the most energ intensive processes used in the dair, ood and chemical industries, it is essential that evaporation be approached rom the viewpoint o economical energ utilization as well as process eectiveness. This can be done onl i the equipment manuacturer is able to oer a ull selection o evaporation technolog and sstems developed to accommodate various product characteristics, the percent o concentration required, and regional energ costs. This handbook describes the man tpes o evaporators and operating options available through the experience and manuacturing capabilities o APV.
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Evaporators Types and Design
In the evaporation process, concentration o a product is accomplished b boiling out a solvent, generall water. The recovered end product should have an optimum solids content consistent with desired product qualit and operating economics. It is a unit operation that is used extensivel in processing oods, chemicals, pharmaceuticals, ruit juices, dair products, paper and pulp, and both malt and grain beverages. Also it is a unit operation which, with the possible exception o distillation, is the most energ intensive. While the design criteria or evaporators are the same regardless o the industr involved, two questions alwas exist: is this equipment best suited or the dut, and is the equipment arranged or the most ecient and economical use? As a result, man tpes o evaporators and man variations in processing techniques have been developed to take into account dierent product characteristics and operating parameters. Types o Evaporators
The more common tpes o evaporators include: Batch pan •
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Forced circulation Natural circulation Wiped ilm Rising ilm tubular Plate equivalents o tubular evaporators evaporators Falling ilm tubular Rising/alling ilm tubular
Batch Pan
Next to natural solar evaporation, the batch pan (Figure 1) is one o the oldest methods o concentration. It is somewhat outdated in i n toda’s toda’s technolog, but is still used in a ew limited applications, such as the concentration o jams and jellies where whole ruit is present and in processing some pharmaceutical products. Up until the earl 1960’s, 1960’s, batch pan also enjoed wide use in the concentration o corn srups. With a batch pan evaporator, product residence time normall is man hours. Thereore, it is essential to boil at low temperatures and high vacuum when a heat sensitive or thermodegradable product is involved. The batch pan is either jacketed or has internal coils or heaters. Heat transer areas normall are quite small due to vessel shapes, and heat transer coecients (HTC’s) tend to be low under natural convection conditions. Low surace areas together with low HTC’s generall limit the evaporation capacit o such a sstem. Heat transer is improved b agitation within the vessel. In man cases, large temperature dierences cannot be used or ear o rapid ouling o the heat transer surace. Relativel low evaporation capacities, thereore, limit its use.
Figure 1 CONDENSER
STEAM
PRODUCT
CONDENSATE
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Tubula ubularr Evapo Evaporato rators rs Natural Circulation
Evaporation b natural circulation is achieved through the use o a short tube bundle within the batch pan or b having an external shell and tube heater outside o the main vessel (Figure 2). The external heater has the advantage that its size is not dependent upon the size or shape o the vessel itsel. As a result, Figure 2 larger evaporation capacities ma be obtained. The most common application or this tpe o unit is as a reboiler at the base o a distillation column. Rising Film Tubular
Considered to be the rst ‘modern’ evaporator used in the industr, the rising lm unit dates back to the earl 1900’s. The rising lm principle was developed commerciall b using a vertical tube with steam condensing on its outside surace (Figure 3). Liquid on the inside o the tube is brought to a boil, with the vapor generated orming a core in the center o the tube. As the fuid moves up the tube, more vapor is ormed resulting in a higher central core velocit that orces the remaining liquid to the tube wall. Higher vapor velocities, in turn, result in thinner and more rapidl moving liquid lm. This provides higher HTC’s HTC’s and shorter product residence time. ti me. The development o the rising lm principle was a giant step orward in the evaporation eld, particularl in product qualit. In addition, higher HTC’s resulted in reduced heat transer area requirements and consequentl, in a lower initial capital investment.
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Figure 3
Falling Film Tubular
Following development o the rising lm principle, it took almost hal a centur or a alling lm evaporation technique to be perected (Figure 4). The main problem was how to design an adequate sstem or the even distribution o liquid to each o the tubes. For the rising lm evaporator, distribution was eas since the bottom bonnet o the calandria was alwas pumped ull o liquid, thus allowing equal fow to each tube. While each manuacturer has its own technique, alling lm distribution generall is based around use o a perorated plate positioned above the top tube plate o the calandria. Spreading o liquid to each tube is sometimes urther enhanced b generating fash vapor at this point. The alling lm evaporator does have the advantage that the lm is ‘going with gravit’ instead o against it. This results in a thinner, aster moving lm and gives rise to an even shorter product contact time and a urther improvement in the value o HTC. To establish a well-developed lm, the rising lm unit requires a driving lm orce, tpicall a temperature dierence o at least 25°F (14°C) across the heating surace. In contrast, the alling lm evaporator does not have a driving orce limitation—permitting a greater number o evaporator eects to be used within the same overall operating limits. For example, i steam is available at 220°F (104°C), then the last eect boiling temperature is 120°F (49°C); the total available ΔT is equal to 100°F (55°C). In this scenario a rising lm Figure 4 evaporator would be limited to our eects, each with a ΔT o 25°F (14°C). However, using the alling lm technique, it is easible to have as man as 10 or more eects.
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Rising/Falling Film Tubular
The rising/alling lm evaporator (Figure 5) has the advantages o the ease o liquid distribution o the rising lm unit coupled with lower head room requirements. The tube bundle is approximatel hal the height o either a rising or alling lm evaporator, and the vapor/liquid separator is positioned at the bottom o the calandria.
Forced Circulation
Figure 5
STEAM
STEAM VACUUM
FEED
PRODUCT OUT
The orced circulation evaporator (Figure 6) was developed or processing liquors which are susceptible to scaling or crstallizing. Liquid is circulated at a high rate through the heat exchanger, boiling being prevented within the unit b virtue o a hdrostatic head maintained above the top tube plate. As the liquid enters the separator where the absolute pressure is slightl less than in the tube bundle, the liquid fashes to orm a vapor. The main applications or a orced circulation evaporator are in the concentration o inversel soluble materials, crstallizing duties, and in the concentration o thermall degradable materials which result in the deposition o solids. In all cases, the temperature rise across the tube bundle is kept as low as possible, oten as low as 3-5°F (2-3°C). This results in a recirculation ratio as high as 220 to 330 lbs (100 to 150 Kg) o liquor per pound (kilogram) o water evaporated. These high recirculation rates result in high liquor velocities through the tube which help to minimize the build up o deposits or crstals along the heating surace. Forced circulation evaporators normall are more expensive than lm evaporators because o the need or large bore circulating pipework and large recirculating pumps. Operating costs o such a unit also are considerabl higher.
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Figure 6
VAPOR OUTLET
SEPARATOR
LIQUOR HEAD TOPREVENT BOILING AT HEATING SURFACE
LOW TEMPERATURE
CONCENTRATED LIQUOR OUTLET
CALANDRIA
RISE ACROSS CALANDRIA
DILUTE LIQUOR INLET
CIRCULATION PUMP GIVING HIGH LIQUOR VELOCITIES OVER HEATING SURFACE
Wiped Film
The wiped or agitated thin lm evaporator has limited applications due to the high cost and is conned mainl to the concentration o ver viscous materials and the stripping o solvents down to ver low levels. Feed is introduced at the top o the evaporator and is spread b wiper blades on to the vertical clindrical surace inside the unit. Evaporation o the solvent takes place as the thin lm moves down the evaporator wall. The heating medium normall is high pressure steam or oil. A high temperature heating medium generall is necessar to obtain a reasonable evaporation rate since the heat transer surace available is relativel small as a direct result o its clindrical conguration. The wiped lm evaporator is satisactor or its limited applications. However, in addition to its small surace area, it also has the disadvantage o requiring moving parts such as the wiper blades which, together with the bearings o the rotating shat, need periodic maintenance. Capital costs in terms o dollars per pound o solvent evaporated also are ver high. 9
Plate Type Evaporators
To eectivel concentrate an increasing variet o products which dier b industr in such characteristics as phsical properties, stabilit, or precipitation o solid matter, equipment manuacturers have engineered a ull range o evaporation sstems. Included among these are a number o plate tpe evaporators (Figure 7). Plate evaporators initiall were developed and introduced b APV in 1957 to provide an alternative to the tubular sstems that had been in use or hal a centur. The dierences and advantages were man. The plate evaporator, or example, oers ull accessibilit to the heat transer suraces. It also provides fexible capacit merel b adding more plate units, shorter product residence time resulting in a superior qualit concentrate, a more compact design with low headroom requirements, and low installation cost.
Figure 7
These APV plate evaporation sstems are made in our arrangements — Rising/Falling Film, Falling Film, Paravap, and Forced Circulation — and ma be sized or use in new product development or or production at pilot plant or ull scale operating levels. APV plate tpe evaporators have been sold commerciall or over 50 ears. Approximatel 2000 sstems have been manuactured b APV or the concentration o hundreds o dierent products. 10
Applications
Although plate evaporators can be used on a broad range o products, the main application has been with products that are heat sensitive and thereore benet rom the high HTC’s and low residence time. Products that are being processed in this evaporator include:
· Apple juice · Amino acids · Bee broths · Beet juice · Betacclodextrin · Caragenan · Cheese whe · Chicken broth · Citrus juice
· Coee · Fruit purees · Gelatin · Grape juice · Lime juice · Liquid egg · Low alcohol beer · Mango juice · Orange juice
· Pear juice · Pectin · Pharmaceutical products · Pineapple juice · Skim milk · Sugars · Vegetable juices · Whe protein · Whole milk
Rising/Falling Film Plate
This is the original plate tpe evaporator. The principle o operation or the rising/ alling lm plate evaporator (RFFPE) involves the use o a number o plate packs or units, each consisting o two steam plates and two product plates. These are hung in a rame which resembles that o a plate heat exchanger (Figure 8). The rst product passage is a rising pass and the second, a alling pass. The steam plates, meanwhile, are arranged alternatel between each product passage.
Figure 8
steam
condensate product feed
vapor/liquid product
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The product to be evaporated is ed through two parallel eed ports and is equall distributed to each o the rising lm annuli. Normall, the eed liquor is introduced at a temperature slightl higher than the evaporation temperature in the plate annuli, and the ensuing fash distributes the eed liquor across the width o the plate. Rising lm boiling occurs as heat is transerred rom the adjacent steam passage with the vapors that are produced helping to generate a thin, rapidl moving turbulent liquid lm. During operation, the vapor and partiall concentrated liquid mixture rises to the top o the rst product pass and transers through a ‘slot’ above one o the adjacent steam passages. The mixture enters the alling lm annulus where gravit urther assists the lm movement and completes the evaporation process. The rapid movement o the thin lm is the ke to producing low residence time within the evaporator as well as superior HTC’s. At the base o the alling lm annulus, a rectangular duct connects all o the plate units and transers the evaporated liquor and generated vapor into a separating device. A fow schematic or a two eect sstem is shown in (Figure 9).
Figure 9
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The plate evaporator is designed to operate at pressures extending rom 10 psig (1.7 barg) to ull vacuum when using an number o eects. However, the maximum pressure dierential normall experienced between adjacent annuli during single eect operation is 15 psi (1 bar). This, and the act that the pressure dierential alwas is rom the steam side to the product side, considerabl reduce design requirements or supporting the plates. The operating pressures are equivalent to a water vapor saturation temperature range o 245°F (118°C) downwards, and thus are compatible with the use o nitrile or butl rubber gaskets or sealing the plate pack. Most rising/alling lm plate evaporators are used or duties in the ood, juice and dair industries where low residence time and a temperature lower than 195°F (90°C) are essential or the production o qualit concentrate. Also, increasing number o plate evaporators are being operated successull in both pharmaceutical and chemical plants on such products as antibiotics and inorganic acids. These evaporators are available as multi-eect and/or multi-stage sstems to allow relativel high concentration ratios to be carried out in a single pass, non-recirculating fow. The rising/alling lm plate evaporator should be given consideration or various applications that: •
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Require operating temperatures between 80-212°F (26 to 100°C) Have a capacit range o 1000-35,000 lbs/hr (450 to 16,000 kg/hr water removal Have a need or uture capacit increase since evaporator capabilities can be extended b adding plate units or b the addition o extra eects Require the evaporator to be installed in an area that has limited headroom as low as 13 t (4m) Where product qualit demands a low time/temperature relationship Where suspended solid level is low and eed can be passed through 50 mesh screen
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A ‘Junior’ ‘Junior’ version o the evaporator (Figure 10) is available or pilot plant and test work and or low capacit production. I necessar, this can be in multi-eect/multi-stage arrangements. Figure 10
Falling Film Plate
Incorporating all the advantages o the original rising/alling lm plate evaporator sstem with the added benets o shorter residence time and larger evaporation capabilities, the alling lm plate evaporator has gained wide acceptance or the concentration o heat sensitive products. With its larger vapor ports, evaporation capacities are tpicall up to 60,000 lbs/hr (27,000 kg/hr). Figure 11 The alling lm plate evaporator consists o gasketed plate units (each with a product and a steam plate) compressed within a rame that is ducted to a separator. The The number o plate units used is determined b the dut to be handled. One o the important innovations in this tpe o evaporator is the patented eed distribution sstem (Figure 11). Feed liquor rst is introduced through an orice (1) into a chamber (2) above the product plate where mild fashing occurs. This vapor/liquid mixture then passes through a single product transer hole (3) into a fash chamber (4) which extends across the top o the adjacent steam plate. More fash vapor results as pressure is urther reduced and the mixture passes in both directions into the alling lm plate annulus through a row o small distribution holes (5). These assure an even lm fow down the product plate surace where evaporation occurs. A unique eature is the abilit to operate the sstem either in parallel or in series, giving a two-stage capabilit to each rame. This is particularl advantageous i product recirculation is not desirable. 14
Figure 12
In the two-stage method o operation, eed enters the let side o the evaporator and passes down the let hal o the product plate where it is heated b steam coming rom the steam sections. Ater the partiall concentrated product is discharged to the separator, it is pumped to the right side o the product plate where concentration is completed. The nal concentrate is extracted while vapor is discharged to a subsequent evaporator eect or to a condenser. The alling lm plate is available in an extended orm which provides up to 4000 t2 (370m2) surace area in one rame. A fow schematic or a two eect sstem (Figure 12) is shown above. An APV alling lm plate evaporator in triple eect mode (Figure 13) is shown below.
Figure 13. Plant representation. Triple-eect Triple-eect Falling Film Evaporator Evaporator sstem ollowed b b a double-eect orced circulation tubular nisher. A distillation essence recover sstem was provided to recover the ke essence components rom the juice and in particular the methl anthranilate.
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The APV AP V Paravap Evaporation Sstem The Process
The APV Paravap evaporation sstem is designed or the evaporation o highl viscous liquids. The sstem is oten used as a nishing evaporator to concentrate materials to high solids ollowing a low solids multi-eect or MVR lm evaporator. The main components o the sstem are a plate heat exchanger, vapor liquid separator, condenser and a series o pumps (Figure 14). It is designed to operate as a climbing lm evaporator with the evaporation taking place in the plate passages. Compared with orced circulation evaporators, the pumping costs are signicantl reduced. Under normal operating conditions the eed is introduced at the bottom o the plates. As the eed contacts the plate surace, which is heated b either steam or hot water, the eed starts to evaporate. The narrow gap and corrugations in the plate passages cause high turbulence and a resulting partial atomization o the fuid. This reduces the apparent liquid viscosit and generates considerabl higher HTC’s than would occur in a shell and tube heat exchanger under similar conditions. It is particularl eective with non-Newtonian viscous liquids.
Figure 14
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A clear advantage when processing temperature sensitive products is gained with a Paravap because most duties do not require liquid recirculation. For most duties the conventional gasketed plate heat exchanger is specied. However, or duties where the process fuid could attack the gasket, APV can oer the welded plate pair exchanger which eliminates elastomer gaskets on the process side. The Paravap is usuall operated in single eect mode although some sstems are operating with double eect. Since most sstems are not phsicall large, the equipment can oten be ull preassembled on a skid prior to shipment. Preassembl reduces installation time and, in most cases, signicantl lowers the overall project cost. The Paravap evaporation sstem is particularl eective in processing the more viscous products. Oten the Paravap can be used in place o a wiped lm or thin lm evaporator with a substantial reduction in cost. For duties where severe ouling can occur on boiling heat transer suraces, the process should be perormed in an APV Forced Circulation Evaporator. Some tpical duties that are perormed in a Paravap include: •
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Sodium hdroxide Concentration o sugar solutions to extremel high solids content In one case a solids concentration o 98% was achieved Removal o water rom soaps Finishing concentrator on certain ruit purees such as banana and apple Concentration o high solids corn srups
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Removal o solvents rom vegetable oils
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Concentration o abric soteners
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Lignin solutions High concentration gelatin High concentration chicken broth
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The APV Forced Circulation Evaporator Sstem The Process
The APV Forced Circulation Evaporator Sstem is designed or the evaporation o liquids containing high concentrations o solids. In particular, the sstem is used as a nishing evaporator to concentrate materials to high solids ollowing a low solids multieect or MVR lm evaporator. The main components o the sstem are a plate heat exchanger, vapor liquid separator, condenser and a series o pumps (Figure 15). It is designed to operate as a orced circulation evaporator with the evaporation being suppressed in the heating section b back pressure. This back pressure can be generated b a liquid head above the exchanger or b using an orice piece or valve in the discharge rom the evaporator. The evaporation then occurs as the liquid fashes in the entrance area to the separator. The suppression o boiling, together with the high circulation rate in the plate heat exchanger, result in less ouling than would occur in other tpes o evaporators. This increases the length o production runs between cleanings. In addition, the narrow gap and corrugations in the plate passages result in ar higher heat transer rates than would be obtained in shell and tube sstems.
Figure 15
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For most duties the conventional gasketed plate heat exchanger is specied. However or duties where the process fuid could attack the gasket, APV can oer the welded plate pair exchanger which eliminates elastomer gaskets on the process side. The APV Forced Circulation Evaporator Sstem can be used either as a single or multiple eect evaporator. Since man sstems are not phsicall large, the equipment can oten be ull preassembled on a skid prior to shipment. Preassembl reduces installation time and, in most cases, signicantl lowers the overall project cost. Because o the large range o viscosities that can be handled in a orced circulation evaporator, this orm o evaporator can economicall handle a wider range o duties than an other evaporator. In particular, due to the high turbulence and corresponding high shear rates, the APV Forced Circulation Evaporator is excellent at handling nonNewtonian fuids with high suspended solids content. Some tpical duties that are perormed in an APV Forced Circulation Evaporator include: •
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Concentration o wash water rom water based paint plants to recover the paint and clean the water Removal o water rom destus prior to dring Finishing concentrator on waste products rom breweries and distillerie Concentration o brewer’s brewer’s east Concentration o kaolin slurries prior to dring Recover o solvents in wastes rom cleaning operations
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Evaporation o solvents rom pharmaceutical products
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Crstallization o inorganic salts
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Cheese whe
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Evaporator Tpe Selection The choice o an evaporator best suited to the dut on hand requires a number o steps. Tpical Tpical rules o thumb or the initial selection are detailed below. A selection guide (Figure 16), based on viscosit and the ouling tendenc o the product is shown below on next page. Mode o Evaporation
The user needs to select one or more o the various tpes o evaporator modes that were described in the previous section. To perorm this selection, there are a number o ‘rules o thumb’ which can be applied. Falling lm evaporation: — either plate or tubular, provides the highest heat transer coecients — is usuall the mode chosen i the product permits — will usuall be the most economic — is not suitable or the evaporation o products with viscosities over 300cp — is not suitable or products that oul heavil on heat transer suraces during boiling
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Forced circulation evaporators: — can be operated up to viscosities o over 5,000cp — will signicantl reduce ouling — are expensive; both capital and operating costs are high Paravap evaporators: — are suitable or viscosities up to 10,000cp or low ouling duties — are suitable or ver high viscosities, i.e., over 20,000cp, usuall the onl suitable evaporation modes are the wiped lm and thin lm sstems
Film Evaporators—Plate or Tubular •
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Plate evaporators: — provide a gentle tpe o evaporation with low residence times and are oten the choice or duties where thermal degradation o product can occur — oten provide enhanced qualit o ood products — require low headroom and less expensive building and installation costs — are easil accessed or cleaning — provide added fexibilit, since surace area can easil be added or removed Tubular evaporators: — are usuall the choice or ver large evaporators — are usuall the choice or evaporators operating above 25 psia (1.7 bar) — are better at handling large suspended solids — require less foor space than plate evaporators — have ewer gasket limitations
Forced Circulation Evaporators—Plate or Tubular •
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Plate sstems will provide much higher HTC’s or all duties. duti es. With viscous products, the plate exhibits vastl improved perormance compared with a tubular. Tubular sstems must be selected when there are particulates over 2mm diameter.
The APV Paravap •
For low ouling viscous products such as high brix sugar, the Paravap sstem is alwas the preerred solution.
High
Wiped Film Paravap
Figure 16 This diagram shows a selection guide based on the viscosit and ouling tendenc o the product.
y t i s o c s i V
Low
Film
Forced Circulation Plate or Tubular Recirculated Film Fouling
High 21
Materials o Construction
The two parameters which control the selection o the material o construction are corrosion and ease o cleaning. All evaporators or hgienic duties must be capable o being requentl cleaned in place. In most cases, this means rinsing the equipment with water, ollowed b washing with caustic and then acid cleaning agents, and nall, a urther rinsing with water. It is important, particularl with dair and meat products, that the evaporator is completel cleaned o all deposits. The cleaning processes eliminate the use o carbon steel as the material o construction. Most hgienic evaporators are manuactured in either 304 or 316 stainless steel. Corrosion is oten a major problem with chemical duties and some hgienic applications. A particular problem with evaporators is the range o concentration o solids in the process fuid, since the corrosive component will be concentrated as it passes through the evaporator. In some evaporators, the concentration range can be as high as 50 to 1. For example, waste water with a chloride content o 40ppm in the eed would have 2000ppm in the product. While stainless steel would be acceptable or the initial stages o evaporation, a more corrosion resistant material would be required or the last one or two stages. Corrosion is also a major consideration in the selection o gasket materials. This is particularl important with plate evaporators with elastomeric gaskets sealing each plate. Man solvents such as chlorinated and aromatic compounds will severel attack the gaskets. A less obvious orm o attack is b nitric acid. This is important since nitric acid can be present in some cleaning materials. While concentrations o about 1% up to 140°F (60°C) can be accepted, it is best to eliminate nitric acid rom cleaning materials. Phosphoric and sulamic acids are less aggressive to gaskets.
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It is not the purpose o this handbook to provide guidelines or the selection o materials o construction. The reader is reerred to the APV Corrosion Handbook, as well as the man publications issued b the material manuacturers. Tpical materials o construction or a number o evaporator applications are shown below:
Product Most dair and ood products Most ruit juices Sugar products Foods containing high salt (NaCl)
Caustic soda < 40% Caustic soda high concentration Hdrochloric acid
Material o Construction 304/316 stainless steel 316 stainless steel Carbon steel /304/316 Titanium/Monel High allo stainless steels Duplex stainless steels Stress relieved carbon steel Nickel Graphite/Rubber lined carbon steel
In some cases, the tpe o evaporator is controlled b the materials o construction. For example a suluric acid evaporator, where the acid concentration can reach 50%, would utilize graphite tubular heat exchangers and non-metallic separators and piping.
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Evaporator Congurations or Energ Conservation Conservation o energ is one major parameter in the design o an evaporator sstem. The larger the evaporation dut, the more important it is to conserve energ. The ollowing techniques are available: Multi-Eect Evaporation
Multi-eect evaporation uses the steam produced rom evaporation in one eect to provide the heat to evaporate product in a second eect which is maintained at a lower pressure (Figure 17). In a two eect evaporator, it is possible to evaporate approximatel 2 kgs o steam rom the product or each kg o steam suppl. As the number o eects is increased, the steam econom increases. On some large duties it is economicall easible to utilize as man as seven eects. Increasing the number o eects, or an particular dut, does increase the capital cost signicantl and thereore each sstem must be careull evaluated. In general, when the evaporation rate is above 3,000 lbs/h (1,350 kg/h), multi-eect evaporation should be considered.
Figure 17
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Thermo Vapor Recompression (TVR)
When steam is available at pressures in excess o 45 psig (3 barg) and preerabl over 100 psig (7 barg), it will oten be possible to use thermo vapor recompression. In this operation, a portion o the steam evaporated rom the product is recompressed b a steam jet venturi and returned to the steam chest o the evaporator. A sstem o this tpe can provide a 2 to 1 econom or higher depending on the product the steam pressure and the number o eects over which TVR is applied. TVR is a relativel inexpensive technique or improving the econom o evaporation. TVR can also be used in conjunction with multi-eect to provide even larger economies (Figure 18). Shown in (Figure 19) are the economies that can be achieved. Thermocompressors are somewhat infexible and do not operate well outside the design conditions. Thereore i the product is known to oul severel, so that the heat transer coecient is signicantl reduced, it is best not to use TVR. The number o degrees o compression is too small or materials that have high boiling point elevation.
Figure 18 25
Figure 19
Mechanical Vapor Recompression (MVR)
Thermodnamicall, the most ecient technique to evaporate water is to use mechanical vapor thermorecompression. This process takes the vapor that has been evaporated rom the product, compresses the vapor mechanicall and then uses the higher pressure vapor in the steam chest (Figure 20). The vapor compression is carried out b a radial tpe an or a compressor. The an provides a relativel low compression ratio o 1:30 which results in high heat transer surace area but an extremel energ ecient sstem. Although higher compression ratios can be achieved with a centriugal compressor, the an has become the standard or this tpe o equipment due to its high reliabilit, low maintenance cost and generall lower RPM operation.
Figure 20
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This technique requires onl enough energ to compress the vapor because the latent heat energ is alwas re-used. Thereore, an MVR evaporator is equivalent to an evaporator o over 100 eects. In practice, due to ineciencies in the compression process, the equivalent number o eects is in the range 30 to 55 depending on the compression ratio. The energ supplied to the compressor can be derived rom an electrical motor, steam turbine, gas turbine and internal combustion engine. In an o the cases the operating economics are extremel good. Since the costs o the compressors are high, the capital cost o the equipment will be signicantl higher than with multi-eect. However in most cases, or medium size to large evaporators, the pa back time or the addition capital will onl be 1 to 2 ears. Like the one TVR, the two MVR sstem is not appropriate or high ouling duties or where boiling point elevation is high.
Combination o Film and Forced Circulation Evaporators
The most economic evaporators utilize alling lm tubulars or plates, with either TVR or MVR. However with man duties, the required concentration o the nal product requires a viscosit that is too high or a lm evaporator. The solution is to use lm evaporation or the pre-concentration and then a orced circulation nisher evaporator to achieve the ultimate concentration; e.g., a stillage or spent distiller wash evaporator. The material would tpicall be concentrated rom 4% to 40% in a alling lm evaporator and then rom 40% to 50% in a orced circulation evaporator. Usuall the nisher would be a completel separate evaporator since the nisher dut is usuall relativel low. In the dut specied above, almost 98% o the evaporation would take place in the high ecienc lm evaporator. For cases where the nisher load is relativel high, it is possible to incorporate the orced circulation nisher as one o the eects in a multi-eect evaporator. However this is an expensive proposition due to the low coecients at the high concentration.
27
Residence Time in Film Evaporation Since man pharmaceutical, ood and dair products are extremel heat sensitive, optimum qualit is obtained when processing times and temperatures are kept as low as possible during concentration o the products. The most critical portion in the process occurs during the brie time that the product is in contact with a heat transer surace which is hotter than the product itsel. To protect against possible thermal degradation, the time/temperature relationship thereore must be considered in selecting the tpe and operating principle o the evaporator to be used. For this heat sensitive tpe o application, lm evaporators have been ound to be ideal or two reasons. First, the product orms a thin lm onl on the heat transer surace rather than occuping the entire volume, greatl reducing residence time within the heat exchanger. Second, a lm evaporator can operate with as low as 6°F (3.5°C) steam-to-product temperature dierence. With both the product and heating suraces close to the same temperature, localized hot spots are minimized. As previousl described, there are rising lm and alling lm evaporators as well as combination rising/alling lm designs. Both tubular and plate congurations are available. Comparison O Rising Film And Falling Film Evaporators
In a rising lm design, liquid eed enters the bottom o the heat exchanger and when evaporation begins, vapor bubbles are ormed. As the product continues up either the tubular or plate channels and the evaporation process continues, vapor occupies an increasing amount o the channel. Eventuall, the entire center o the is lled with vapor while the liquid orms a lm on the heat transer surace.
28
The eect o gravit on a rising lm evaporator is twoold. It acts to keep the liquid rom rising in the channel. Further, the weight o the liquid and vapor in the channel pressurizes the fuid at the bottom and with the increased pressure comes an increase in the boiling point. A rising lm evaporator thereore requires a larger minimum ΔT than a alling lm unit. The majorit o the liquid residence time occurs in the lower portion o the channel beore there is sucient vapor to orm a lm. I the liquid is not preheated above the boiling point, there will be no vapor. And since a liquid pool will ll the entire area, the residence time will increase. As liquid enters the top o a alling lm evaporator, a liquid lm ormed b gravit fows down the heat transer surace. During evaporation, vapor lls the center o the channel and as the momentum o the vapor accelerates the downward movement, the lm becomes thinner. Since the vapor is working with gravit, a alling lm evaporator produces thinner lms and shorter residence times than a rising lm evaporator or an given set o conditions. Tubular And Plate Film Evaporators
When compared to tubular designs, plate evaporators oer improved residence time since the carr less volume within the heat exchanger. In addition, the height o a plate evaporator is less than that o a tubular sstem.
29
Estimating Residence Time
It is dicult to estimate the residence time in lm evaporators, especiall rising lm units. Correlations, however, are available to estimate the volume o the channel occupied b liquid. Formula (1) is recommended or vacuum sstems. For alling lm evaporators, the lm thickness without vapor shearing can be calculated b Formula (2). Since the lm is thin, this can be converted to liquid volume raction in a tubular evaporator b Formula (3). For a alling lm plate evaporator, Formula (4) is used. As liquid travels down the plate and evaporation starts, vapors will accelerate the liquid. To account or this action, the rising lm correlation is used when the lm thickness alls below that o a alling lm evaporator. In practice, the lm thickness ma be less than estimated b either method because gravit and vapor momentum will act on the fuid at the same time. Once the volume raction is known, the liquid residence time is calculated b ormula (5). In order to account or changing liquid and vapor rates, the volume raction is calculated at several intervals along the channel length. Evaporation is assumed to be constant along with channel length except or fash due to high eed temperature.
SyMBOLS A d g L m RL qL t G r L r V
µ
cross sectional area tube diameter gravitational gravitational constant tube length ilm thickness liquid volume raction liquid rate time liquid wetting rate liquid densit vapor densit liquid viscosit local weight raction o vapor
Reerences a) HTRI report, BT-2, pg. 7 (Ma 1978) b) Perr’s Chemical Engineer’s Handbook, 5th edition, 5-57
30
FORMULAS
(1)
1
RL = 1 — 1+
[
(
1—
3Γµ g ρL ( ρL — ρv )
(2)
m=
(3)
RL =
4m d
(4)
RL =
2m Z
(5)
t=
RL AL qL
)(
]
/3
1
2 ρV ρL
)
.5
CONTACT TIME 1st eect 2nd eect 3rd eect 4th eect Total Contact Time (A) two stages
RISING FILM TUBULAR
RISING FILM PLATE (C)
FALLING FILM TUBULAR
FALLING FILM PLATE
88 62 118 236 (A)
47 (A) 20 30 78 (A)
23 22 15 123 (A)
16 (A) 13 9 62 (B)
504
175
183
100
(B) three stages
(C) plate gap .3 in (7.5mms)
The table above shows a comparison o contact times or tpical our-eect evaporators handling 40,000 lb/h (18,000 kg/h) o eed. The tubular designs are based on 2 in. (51 mm) OD tube, 30 eet (9m) long. Incidentall, designs using dierent tube lengths do not change the values or a rising lm tubular sstem. The given values represent total contact time on the evaporator surace, which is the most crucial part o the processing time. Total residence time would include contact in the preheater and separator, as well as additional residence within interconnecting piping. While there is no experimental data available to veri these numbers, experience with alling lm plate and tubular evaporators shows that the values are reasonable. It has been noted that Formula (2) predicts lm thicknesses that are too high as the product viscosit rises. Thereore, in actualit, 4th eect alling lm residence times probabl are somewhat shorter than charted. Summary
Film evaporators oer the dual advantages o low residence time and low temperature dierence which help assure a high product qualit when concentrating heat sensitive products. In comparing the dierent tpes o lm evaporators that are available, alling lm designs provide the lowest possible ΔT, and the alling lm plate evaporator provides the shortest residence time.
31
Designing or Energ Ecienc Although the concentration o liquids b evaporation is an energ intensive process, there are man techniques available, as detailed in previous sections, to reduce the energ costs. However, increased energ ecienc can onl be achieved b additional capital costs. As a general rule, the larger the sstem, the more it will pa back to increase the thermal ecienc o the evaporator. The problem is to select the correct technique or each application. The main actors that will aect the selection o the technique are detailed below. Evaporation Evaporation Rate
The higher the capacit o the evaporator, the more the designer can justi complex and expensive evaporation sstems in order to provide high energ ecienc. For evaporator design purposes, the capacit is dened as the evaporation rate per hour. However, in some applications such as seasonal ruit juice processors, the equipment is onl operated or part o the ear. This means that an expensive evaporator is idle or part o the ear. The economic calculation has to include annual operating hours. For low capacities the designer is less concerned about energ ecienc. I the evaporation rate is below 2,200 lb/h (1000 kg/h), it is dicult to justi multi- eect evaporation. Usuall a single-eect evaporator, oten with thermo vapor recompression (TVR), is the sstem o choice at this capacit. In man cases, mechanical vapor recompression (MVR) is the most ecient evaporator. However, these sstems operate at a low temperature dierence, which results in high heat transer area. Also MVR requires either a centriugal compressor or a high pressure an which are expensive equipment items. These cannot usuall be justied or low capacit evaporators.
32
Steam/Electricity Costs
For medium to large duties, a selection has to be made between multi-eect and MVR. A critical parameter that will aect this selection are steam costs relative to electricit costs. Providing process conditions are avorable, MVR evaporation will be more economic, particularl in areas where the electricit cost is low, such as localities around major hdro generating plants. However i low cost steam is available, even at pressures as low as atmospheric, then multi-eect evaporation will be usuall more economic due to the lower capital cost. Steam Pressure
The availabilit o steam at a medium pressure o about 100 psig (7 barg), permits the ecient use o TVR either on a single or multi-eect evaporator. TVR can be applied across one, two or even three eects. This is the simplest and least costl technique or enhancing evaporator ecienc. The eectiveness declines signicantl as the available steam pressure is reduced. Material o Construction
The majorit o evaporators are made in 304 or 316 stainless steel. However there are occasions that much more expensive materials o construction are required, such as 904L, 2205, nickel, Hastello C, titanium and even graphite. These expensive materials skew the economic balance, with the capital cost becoming more signicant in the equation. Tpicall MVR would become less economic as the material cost increases, due to the size o the heat exchangers required.
33
Phsical Properties There are a number o phsical properties that can severel infuence the selection o an evaporator. Boiling Point Elevation
A boiling point elevation o over 5°F (3°C) essentiall eliminates MVR evaporators rom consideration. This can be partiall circumvented b using MVR as a pre concentrator. Once the concentration is sucient to produce signicant boiling point elevation, the nal evaporation would be perormed in a steam driven nisher. Product Viscosity
High product viscosit o over 300 to 400cp usuall eliminates alling lm evaporators in avor o orced circulation. Forced circulation requires a higher temperature dierence, which eliminates MVR. TVR is used on some duties. Product Fouling
Both MVR and TVR are not particularl suitable or duties where severe ouling o heat transer suraces occurs over a short time period. The perormance o these evaporators will all o more rapidl than with a multi-eect sstem. Forced circulation evaporators with suppressed boiling usuall perorm better with high ouling than lm evaporators. Temperature Sensitive Products
Man products, particularl in the ood industr, are prone to degradation at elevated temperatures. The eect is usuall made worse b extended residence time. This problem limits the temperature range or multi-eect sstems. For example on a milk evaporator, the temperature is limited to a maximum o 160°F (71°C). Since a tpical minimum boiling temperature is 120°F (49°C), there is a limited temperature dierence to perorm the evaporation. This tpe o dut is suitable or MVR since the evaporation occurs at essentiall the same temperature. Although a lower operating temperature increases the size o the major equipment, MVR is the most economic solution or large capacit dair evaporators.
34
In man cases the selection o the energ conservation technique is obvious. However, or man applications it is necessar to evaluate a number o techniques in detail beore a decision can be made. The ollowing case stud illustrates the various options to save energ using dierent techniques. The dut is to concentrate skim milk rom 8% solids to 48% b evaporation. The eed rate is 100,000 lb/h (45,500 kg/h). The data shown in the table below summarizes the perormance and costs or a straight 5 eect evaporator, a 5 eect evaporator with TVR across 3 eects, and a mechanical vapor recompression evaporator. No pasteurizer is included in this cost comparison. Annual operating costs are based on 7,000 h/ear o operation, with a steam cost o $12.50/1000 lb (454 kg) and electricit at $0.085/kwh.
Evaporation Steam Consumed Absorbed power Annual costs Steam Electricit Total Capital costs Equipment
lb/h kg/h lb/h kg/h kw
5 EFFECT
5 EFFECT WITH TVR
MVR
83,000 37,900 17,000 7,700 70
83,000 37,900 11,000 5,000 60
83,000 37,900 0 0 560
$1,487,500 $41,650 $1,529,150
$962,500 $35,700 $998,200
0 $333,200 $333,200
$3,100,000
$3,300,000
$3,750,000
The examples illustrate that with a higher capital investment, it is possible to signicantl reduce the operating costs o the equipment. However the most economic selection is controlled b the steam and electricit prices. For example, i the dair is located alongside an electric co-generation plant, the steam cost would be reduced considerabl lower, and a steam heated evaporator would be the most economic. A less important, but still signicant actor, is the cost o cooling water. An MVR evaporator requires virtuall no cooling water. On a steam heated sstem the cooling water requirement is about 6 US gallons per lb (.05 m3 per kg) o steam applied.
35
Mechanical Vapor Mechanical Vapor Recompression Recompress ion Evaporators Mechanical vapor recompression (MVR) evaporation provides an extremel energ ecient technique or the concentration o solids in water. Usuall the capital cost o an MVR sstem is higher than a comparable steam driven evaporator. However, as the capacit o the sstem increases the relative cost dierence decreases. Although MVR evaporators are seldom chosen or small duties, the concept is oten used or medium to large capacit evaporators. MVR Dened
The basic principle o MVR is to remove the steam that is evaporated rom the product, compress it in a mechanical device, and use the higher pressure steam, which has a corresponding higher saturation temperature, to provide the heating medium or the evaporation (Figure 21). No steam input is required once the sstem is operating. The small dierence in enthalp between the vapors on the condensing and boiling sides is the theoretical energ required to perorm the evaporation. Essentiall, the process re-uses the latent heat o the vapors. The theoretical thermal ecienc o MVR can exceed that o a 100 eect evaporator, although there are a number o practical limitations, such as compressor and motor eciencies which lower the achievable ecienc. The mechanical device can be a centriugal compressor or applications with high compression ratios, or a an or lower compression ratios. For either device, the drive can be an electric motor, steam turbine, internal Figure 21 combustion engine or gas turbine.
36
C 1164.6
B L / U T B Y P L A1153.4 H T N E H
T=243 ˚F
R O S S 1 . E Y 4 R 1 B G P T L R / M E U U P O T N N C E I B
SUPERHEAT AVAILABLE FOR GENERATING EXCESS VAPOR 11.2 BTU/LB
I S P 2 7 . B 1 N T A O L I E H N A S R S U E E O T I P R S C U S L S A P E A M E D E R O D D P I C
A I S P 7 . 1 4
T=220 ˚F
M O C
T=212 ˚F
1150.5
A
ENTHALPY DIFFERENCE AT CONDENSING TEMPERATURES
S A SUPERHEATED T U VAPOR R A T E D V A P O R
2.9 BTU/LB
VAPOR LIQUID MIXTURE 1.7442
Figure 22
1.7568
1.7596
S-ENTROPY BTU/LB ˚F
Thermodynamics o MVR
The process is best explained b reerence to the Mollier—enthalp/entrop diagram or steam (Figure 22). The vapor evaporated rom the product is represented on the Mollier diagram at point A. The actual values in US and metric units are presented on Table 1a and 1b. The vapor enters the compressor at point A. The vapor is then compressed to the higher pressure, at constant entrop at point B. The compressor, which in this case is a an, has ineciencies which results in an increase in entrop above that o the entrop at inlet. This is represented b point C. Vapor at point C is at the required pressure or the steam jacket o the condenser. However, it is superheated and must be cooled in order to condense in the evaporator. This cooling can be perormed on the heat transer surace o the evaporator. However, since desuperheating desuperheatin g HTC’s HTC’s are usuall low, the desuperheating is usuall perormed b the introduction o a spra o condensate into the vapor duct. This condensate vaporizes as the vapor is cooled back to the saturation temperature, and generates more vapor. This condition is represented b point D. At this point most o the vapor is condensed in the evaporator. However, there is an excess o vapor, which is required or heat loss and/or preheat duties. An balance is condensed or vented.
37
PROPERTIES OF WATER VAPOR Pressure-PSIA State Temperature °F H-Enthalp Vapor BTU/LB Latent Heat BTU/LB H-Enthalp Liquid BTU/LB S-Enthalp BTU/LB °F
14.7
17.2
17.2
Saturated 212 1150.5 970.3 180.2 1.7568
Saturated 220 1153.4 965.2 188.2 1.7442
Superheated Superheated 243 1164.6 – – 1.7596
Table 1a. Properties of Water Vapor.
PROPERTIES OF WATER VAPOR Pressure-BAR State Temperature °C H-Enthalp Vapor Kcals/Kg Latent Heat Kcals/Kg H-Enthalp Liquid Kcals/Kg S-Enthalp Kcals/Kg °C
1
1.17
1.17
Saturated 100 639.1 539.0 100.1 1.7568
Saturated 104 640.8 536.2 104.6 1.7442
Superheated 117 647.0 – – 1.7596
Table 1b. Properties of Water Vapor.
In this example, the heat required to evaporate the water is 970.3 Btu (539.0 Kcals). However the compressor input is onl 14.1 Btu (7.8 Kcals), with motor and gearbox losses increasing this to 14.7 Btu (8.16). The equivalent econom is 66 to 1. It should be noted that pressure losses through the evaporator ducting, calandria and separator must be absorbed. This can be achieved b either a higher boost rom the compressor at a higher power, or b accepting a lower temperature dierence and increasing the surace area o the calandria.
38
Types o Compression Equipment
To a large extent, the development o this technolog has been guided b the capabilities o the various tpes o compressors. The ke to the design is the temperature dierence that is available or the evaporator. Table Table 2 shows the th e temperature dierence or various compression ratios at two dierent boiling temperatures. It is this temperature dierence that is available as the driving orce or evaporator, less a small amount required in the orm o lost pressure around the sstem. The original MVR sstems used compressors with compression ratios o about 1.4, which limited the available temperature dierence to 13 to 18°F (7 to 10°C). This limits the MVR to single eect operation. More advanced centriugal compressors were developed in the 1970s, which provided compression ratios o approximatel 2. This provided a much higher temperature dierence, which allowed operation with 2 and 3 eects. This reduces the fow to the compressor and increases the operating ecienc. COMPRESSION RATIO
1.2 1.4 1.6 1.8 2.0
SATURATED ΔT AT BOILING TEMPERATURES 130°F
55°C 55°C
212°F
100°C
6.9 12.9 18.2 23.0 27.3
3.8 7.2 10.1 12.8 15.1
9.3 17.5 24.7 31.2 37.2
5.2 9.7 13.7 17.3 20.7
Table 2. Saturated ΔT at Various Compression Ratios, °F and °C.
A number o evaporators were built with the higher compression sstems in multi-eect mode. Unortunatel, the reliabilit o the compressors became a problem. Because the compressor operates at high speed, it has to be protected rom impingement o water droplets. This usuall requires a mist eliminator in the separator, ollowed b a superheater. An solids carrover will have a detrimental eect on the compressor. In addition, the designer must take care to prevent unstable compressor operation (surging). While the majorit o the compressors unctioned well, there were a ew catastrophic compressor ailures. These ailures caused engineers to review alternative equipment. The answer to the compressor problem was to use a an. This equipment operates at a lower speed and is less vulnerable to damage rom droplets. Fans are also ar less likel to surge. When operated with a variable requenc drive, the ans 39
provide ar greater fexibilit than compressors. The onl disadvantage to the an is that compression ratios are limited to about 1.45. This results in a low available temperature dierence and thereore a high heat transer area. However, the energ ecienc o such sstems is ver high with the equivalent o 55 eects achievable or man duties. Power Requirements
The compressor power requirements to evaporate 1000 lb/h (454 kg/h) o steam at various compression ratios and temperatures are shown in Tables 3a and 3b. Similar data or ans are shown in Tables 4a and 4b. These data correspond quite well with installed MVR sstems. A more detailed comparison between three actual sstems is shown in Table 5. The more energ ecient sstem is the single eect an with a low compression ratio. However, the low temperature dierence will result in high heat transer area in the calandria. In most cases the added capital cost will be justied b lower operating costs. COMPRESSORS Boiling Temp 130°F CR 1.3 1.4 1.6 1.8 2.0 2.2
ΔT 10.00 12.91 18.21 22.98 27.31 31.30
Boiling Temp 170°F
Boiling Temp 212°F
kw
CR
kw
CR
7.0 9.1 12.9 16.5 19.8 22.9
1.3 1.4 1.6 1.8 2.0 2.2
7.5 9.7 13.8 20.0 21.1 27.2
1.3 1.4 1.6 1.8 2.0 2.2
ΔT 11.65 15.03 21.23 26.81 31.89 36.57
ΔT 13.53 17.47 24.69 31.20 37.16 41.31
kw 7.9 10.3 14.7 18.7 22.5 24.9
Table 3a. Power Vs ΔT for Centrifugal Compressors Based on 1000 lb/h of Steam Evaporated. Evaporated.
COMPRESSORS Boiling Temp 55°C CR 1.3 1.4 1.6 1.8 2.0 2.2
ΔT 5.55 7.17 10.11 12.77 15.17 17.39
Boiling Temp 77°C
kw
CR
15.4 20.0 28.5 36.3 43.5 50.3
1.3 1.4 1.6 1.8 2.0 2.2
ΔT 6.47 8.35 11.79 14.89 17.71 20.37
Boiling Temp 100°C
kw
CR
16.4 21.3 30.4 38.7 46.4 53.6
1.3 1.4 1.6 1.8 2.0 2.2
ΔT 7.51 9.71 13.71 17.33 20.64 22.95
Table 3b. Power Vs ΔT for Centrifugal Compressors Based on 454 kg/h of Steam Evaporated. Evaporated.
40
kw 17.5 22.7 32.4 41.3 49.4 57.1
Small MVR Evaporators
For small sstems, rotar blowers were occasionall specied in an attempt to make MVR economic at evaporation capacities less than 15,000 lb/h (7000 kg/h). While there were cost savings, there were also reliabilit problems with this equipment or this particular application. The conclusion remained that or small sstems, it is usuall best to use steam driven evaporators. FANS Boiling Temp 130°F CR 1.1 1.2 1.3
ΔT
3.59 6.91 10.00
kw 2.22 4.31 6.28
Boiling Temp 170°F
Boiling Temp 212°F
CR 1.1 1.2 1.3
CR 1.1 1.2 1.3
ΔT
4.17 8.04 11.65
kw 2.38 4.60 6.71
ΔT
4.85 9.34 13.53
kw 2.54 4.92 7.15
Table 4a. Power Vs ΔT for Fans Based on 1000 lb/h of Steam Evaporated.
FANS Boiling Temp 55°C CR 1.1 1.2 1.3
ΔT 1.99 3.84 5.56
Boiling Temp 77°C
kw
CR
4.90 9.49 13.81
1.1 1.2 1.3
ΔT 2.32 4.47 6.47
Boiling Temp 100°C
kw
CR
5.22 10.12 14.75
1.1 1.2 1.3
ΔT 2.69 5.19 7.52
kw 5.58 10.81 15.73
Table 4b. Power Vs ΔT for Fans Based on 454 kg/h of Steam Evaporated. Evaporated.
Compression Ratio Total ΔT Available Vapor to Compressor Total Power Kw Equivalent Steam Equivalent Steam Econom Average ΔT Per Eect Beore Losses NOTE:
SINGLE EFFECT FAN
DOUBLE EFFECT CENTRIFUGAL
TRIPLE EFFECT CENTRIFUGAL
1.2 6.9°F (3.8°C) 60,000 lb/h (27,300 kg/h) 280 870 lb/h (395 kg/h)
1.6 18.2°F (10.1°C) 30,000 lb/h (13,650 kg/h) 390 1315 lb/h (600 kg/h)
2.0 27.3°F (15.2°C) 20,000 lb/h (9,090 kg/h) 400 1347 lb/h (612 kg/h)
69 6.9°F 6.9°F (3.8°C)
45.6 9.1°F 41.2°F (5.1°C)
44.5 9.1°F 41.2°F (5.1°C)
In this example, the an horsepower is lower than either o the centriugal designs, but the lower ΔT required the greater the surace area.
Table 5. Comparison of Typical MVR Designs — Approximate boiling temperature — 130°F (55°C) evaporation rate—60,000 lb/hr (27,000 kg/h).
41
Evaporators or Industrial and Chemical Applications The APV range o evaporators covers man duties in the concentration o chemicals and industrial products, with both lm and orced circulation sstems being available as required. Film evaporators are used when there is little or no risk o ouling o the heating suraces. Where such a risk is present, orced circulation units are recommended. All designs are suitable or multi-eect evaporation. At low concentrations, mechanical vapor recompression can be emploed. Ater selecting the tpe o evaporator required or a particular dut, the most important actor is the selection o the materials o construction. Man duties can be handled with 316 stainless steel. For some applications where chloride ions are present, higher grades o stainless steel, such as 904L, can be an economic selection. Certain products are so corrosive that the cannot be processed in conventional metals. As an example, concentration o a suluric acid solution o up to 50% at 302°F (150°C) would call or main plant items o lament wound berglass reinorced epox resin, and heating and cooling suraces o impervious graphite. I the suluric acid solution is between 50 and 80% with temperatures up to 230°F (110°C), main plant items should be lead-lined mild steel protected with reractories or carbon tiles. Heat transer suraces again would be o impervious graphite. A tpical sstem (Figure 23) is shown here. It should be noted that APV does not market non-metallic evaporators.
Figure 23
42
Titanium Sulate
The production o titanium dioxide pigments involves reaction between suluric acid and the ore which contains iron, titanium sulate and other compounds. Ater pretreatment, which includes the crstallization o iron as errous sulate, the liquor is heated and hdrolzed to precipitate titanium dioxide. Prior to this operation, the concentration o liquor has to be adjusted b the evaporation o water. It is essential that this process takes place in an evaporator with short heat contact times in order to avoid the premature hdrolsis that occurs with prolonged heating, which subsequentl causes ouling o the heat surace and blockage o the tubes. Although the liquor contains a high proportion o suluric acid, the presence o other ions in solution ma inhibit corrosion, so that copper oten can be used or heat transer suraces. Titanium is another material used or this application. Generall, single or multiple eect rising lm evaporators are used or this dut, the number o eects being determined b throughput and b assessing the cost o operation against the increase in capital required or additional equipment. In some cases, it is economicall attractive to operate the evaporator as a single eect unit at atmospheric pressure using the vapor given o or preheating. The liquor is discharged at a temperature in excess o 212°F (100°C), reducing the subsequent thermal load at the hdrolsis stage. Phosphoric Acid
Phosphoric acid can be produced b the digestion o phosphate rock (calcium phosphate and fuoride among others) in suluric acid, better known as the “wet process” acid. Since calcium sulate normall is a constituent, scaling must be considered. Phosphate rock varies in composition, and in general, periodic cleaning is required even in orced circulation evaporators. Suluric acid plants oten are located along coastal areas, and a urther problem in concentration stems rom the use o sea water in the direct contact condensers. With silica present in the phosphate rock, fuorine reacts to orm hdrofuorosilicic acid (H2SiF6) which in turn, orms a sodium salt rom the NaCl. Sodium fuorosilicic can block the condensers. 43
Ammonium Nitrates
This material has several signicant properties: Low viscosit which allows it to be concentrated to 99+% w/w when it is prilled.
•
•
•
Above 95%, ammonium nitrate has an extremel high boiling point elevation which requires exceedingl high steam pressures or heating. This presents considerable mechanical problems. An organic impurit has the potential or explosion, such that extra low carbon stainless steels must be used or heat transer suraces, and the use o mineral oils or heating is excluded.
The tpe o evaporator best suited or ammonium nitrate depends upon the initial and nal concentrations. For the range below 70% and up to 80-85%, rising lm multieect evaporator units have been used successull. For 80-96% concentrations, conventional alling lm sstems have been emploed. Above 96%, however, alling lm with a heated air sweep would be used due to partial pressure conditions. In areas o relativel low humidit, 99+% water to water can be achieved. Ammonium Sulate
Ammonium sulate is used in batter spacer plate production and also has been crstallized. In this process, small but regular sized crstals are mixed with a PVC tpe plastic and dissolved out o the nal sheet which then is used as spacer plate. Stainless steel has been successull emploed as the material o construction. Barium Salts
The production o barium salt involves the use o sodium sulde, a material which closel resembles caustic soda in both phsical and corrosive properties. It generall is concentrated in a high vacuum crstallizer or the production o barium hdroxide with rubber lined mild steel being used as the material o construction due to corrosion considerations. With liquid temperatures below 72°F, 72°F, two hdrates, mono and a nd penta, can be produced on separate fakers.
44
Glycerine
Sweet water glcerine containing no NaCl has been handled in simple stainless steel lm evaporators b salt and oleo chemical producers. For sodium chloride bearing liquors as in spent le or industrial detergent and soap manuacture, cupronickel allos must be used. When the glcerine is contaminated with salt, the special application o orced circulation crstallizers has been emploed or the recover o the glcerine liquor and separation o the NaCl salts. Caustic Soda
The most common process or the manuacture o caustic soda is the electrolsis o sodium chloride brine. The electroltic processes produce a caustic soda solution that has to be concentrated b evaporation. This evaporation process is dicult since caustic soda solutions have a high boiling point elevation (BPE). At 50% concentration the BPE is about 80°F (45°C). This limits the number o eects usuall to three, with the evaporator operated in reverse fow so that the highest concentration in on the rst eect. This eect will tpicall operate at over 260°F (125°C). An additional problem is that at high temperature, caustic soda solutions corrode stainless steel. The rst and second eect calandrias are usuall abricated in nickel, which is resistant to corrosion. The third eect can be Avesta 254SLX, which is ar less expensive than nickel. The vapor side o the evaporator can be 304 stainless steel and sometimes carbon steel. Tubular alling lm evaporators have been the standard or this application. application. In recent ears, APV has emploed a plate evaporator or caustic soda. The plate emplos nickel welded pairs and proprietar gaskets. The APV design or caustic soda has proven to be the best solution to minimize nickel pickup, which is important to the bleach manuacturing industr.
45
Solvent Recovery
Not all evaporation processes are limited to the removal o water. Some applications require the concentration o a solution o solids and organic solvents. Organic solvents are requentl used or the extraction o products rom raw materials or ermented broths. The solvent then has to be removed rom the extracted product. A tpical application would be the evaporation o acetone rom vegetable oils. For these tpes o duties it is necessar to use explosion proo electrical equipment and intrinsicall sae instrumentation. It is also necessar to observe environmental regulations particularl since some solvents, such as methlene chloride are classied as regulated compounds with stringent discharge limits to both air and water. The sstem must be designed without leaks and with conservation devices on all possible vents. For evaporator selection, the normal guidelines that are used or the evaporator o water remain the same. The onl major dierence is that HTC’s are signicantl lower or organic solvents. A solvent evaporator (Figure 24) is shown below.
Figure 24
46
Waste Water Eva Evapora porators tors As the world has become more concerned about the environment, there has been an increase in the application o evaporator sstems to waste water treatment. These tpes o evaporators essentiall reduce the volume o the waste b removing and recovering most o the water in the waste. In some applications, the concentrate contains product o value, which can be sold or urther processed in a drer to a solid product. In cases where the product has no value, the concentrate can be dried and the resulting product buried in a landll. Since the condensate rom these evaporators is usuall quite pure, the water that is recovered can be used as boiler eed, as rinse fuid or cleaning or merel disposed into the sewer or directl into a river. As with the processing o an waste product, there are usuall severe cost restraints since, unless orced b regulation, ew organizations wish to spend valuable capital on waste treatment processes. The equipment thereore has to have both low capital and operating costs. The ke points in the design o a waste water evaporator are: •
•
Flow rate: this is usuall quite high or these evaporators Solids concentration in the eed: this is usuall quite low
•
Product concentration and the viscosit o the product at that concentration
•
Problems with possible volatile components in the eed
•
•
•
Corrosive nature o the eed: since ma waste water evaporators have high concentration ratios, the eects o corrosion can be enhanced in the nal stages o evaporation Potential or ouling: this can be ver serious in man cases. Boiling point elevation
Because o the large duties, mechanical vapor recompression (MVR) evaporation is usuall the choice. However i boiling point elevation is high, the MVR would be limited to the pre concentration and would require a separate steam powered single or multieect nisher to arrive at the nal concentration. The presence o volatile components in the eed, such as ethanol, can also limit the application o MVR. In this case, it is usuall necessar to remove the volatile components in a stripper column. In a multieect evaporator the stripper column can be placed between eects, which allows recover o the heat needed to operate the stripper.
47
Brewery/Distillery Efuents
The efuents rom brewer and distiller plants are oten processed with evaporators to recover the water and produce a concentrated srup, which can be sold in liquid orm, or added to the spent grains prior to dring. In this case the solids have value as animal ood. Both MVR and multi-eect evaporators have been used or these tpes o dut. Normall alling lm tubular calandrias would be used or the pre evaporator with orced circulation plate or tubular evaporators as the nisher. As in most applications the viscosit o the product at the evaporation temperature controls the point at which the material has to be processed in a orced circulation sstem. An MVR stillage evaporator (Figure 25) is shown below. The problem with these applications is that the product, which can be called stillage, spent wash, spent grains or pot ale, is extremel variable. In particular the viscosit characteristics o the concentrated liquids depend on the raw material grain. Waste water produced rom plants using corn (maize) as the eed stock are relativel eas to process. However, waste water rom plants which use wheat or barle as the eedstock will be ar more viscous at elevated concentrations. In some cases, the viscosit characteristics will be so bad that even a orced circulation evaporator will onl be able to concentrate to 35% solids. This usuall means treating the eed with enzmes prior to evaporation so that a solids concentration o 45% solids can be achieved. The higher the viscosit, the more requentl the evaporator will have to be cleaned. The accepted run time in the industr is 6 to 8 das. To achieve this, it is usuall necessar to provide high recirculation around the calandrias to provide a high wetting rate and prevent burn on. On the nisher, it is occasionall necessar to provide duplex heat exchangers, so that one can be cleaned while the other is in operation.
Figure 25 48
Black Liquor
Black liquor is a caustic waste water generated at paper plants. The quantit o this material produced is large, and some o the largest evaporator applications are with black liquor. An evaporator, designed b APV, APV, or a eed rate o 170 ton/h (Figure 26), is shown here. Tpicall black liquor contains cont ains about 3% solids, o which about hal is caustic soda. The presence o this caustic soda results in quite high boiling Figure 26 point elevation as the concentration increases. This places some restrictions on the application o MVR, so that most black liquor evaporators are multi-eect.
This waste water also varies rom plant to plant, and the concentrate properties are extremel dependent on the eedstock. The product viscosit (Figure 27) is plotted against % solids or dierent tpes o eedstock. In some cases there is a tenold dierence in viscosit.
p
103
p
p
s
102
s s
m s
5
m
p
P C
s l
s
101
5
m
p
s
l
p
5
m
m
VISCOSITY OF BLACK LIQUORS AT 90˚C l
m 5 l
5
m
5
s
100 m
s
l
0.3
s p
5
l m
5
l
Figure 27
5
10
BAMB BAMBOO OO (KRA (KRAFT FT)) PINE (1) EUCALYPTUS (PREHYDROLYSIS KRAFT) BAGA BAGASS SSE E (KRA (KRAFT FT)) BAGA BAGASS SSE E (SOD (SODA A) STRAA (KRAFT) (3) NEWTONIAN NON-NEWTONIAN
20
30
40
% SOLIDS
50
60
70
49
Evaporator Control The control o most chemical/industrial evaporator sstems is quite simple. However, with hgienic evaporators the control is somewhat more complicated due to the need to start up, operate, shut down and then clean at quite requent intervals. As a result sophisticated control is more likel to be needed on hgienic sstems. On almost all evaporation sstems there are onl two basic objectives: To concentrate a liquid to a pre-dened solids content conten t
•
•
To process a pre-dened eed rate o raw material
Theoreticall this can be achieved with onl two control loops. However in practice there are additional loops or level control and pressure control. Product concentration has been measured using reractive index, densit and viscosit techniques. Over the last ten ears, the use o mass fow meters or densit measurement has become the standard. This tpe o meter provides an accurate measurement (usuall out to the 4th decimal place) o both fow and densit. The densit measurement, which is easil converted to a solids content, can then be used to control either product removal rate rom the evaporator, steam fow, or eed fow. There are two techniques used to control evaporators, and the choice is based on the design o the evaporator. In applications where liquid recirculation is required to maintain sucient wetting in the nal stage o the evaporator, the product concentration control is simple and accurate. The procedure is to set the steam fow rate at the design value, remove product based on densit in the recirculation loop, and adjust the eed fow to maintain liquid levels in the evaporator. When a higher throughput is required, then the steam rate is increased. This technique provides excellent control o the product concentration with conventional analog controllers.
50
For heat sensitive products, it is best to avoid recirculation whenever possible. In the case o once-through-fow in the nal stage, there is no recirculation loop in which to install the transmitter and to dela discharge o product when not on specication. In this case, the method is to set the eed fow rate to the desired value and then change the energ input to produce the product concentration required. The energ input ma be the steam rate or the power into the MVR. This technique does not control product qualit particularl accuratel, since response is slow. However it is satisactor or most purposes, and the user can alwas appl more sophisticated PLC control when necessar. Almost all evaporators will have to be cleaned at some time. Some chemical evaporators ma run or months between cleaning ccle. Also with non-hgienic duties, the onl requirement is to clean the heat transer surace sucientl to restore design perormance. In the case o hgienic evaporators, the concern is not onl plant operation, but also contamination rom bacteria. Tpicall, Tpicall, a hgienic evaporator will be cleaned ever da. Dair evaporators, which are designed and constructed to 3A standards, are subject to one o the highest cleaning standards. The inspector will expect that the equipment be cleaned completel with no residue let on an suraces. The potential labor costs to start up, shut down and go through a complex cleaning ccle, on a dail basis, are ver high. A ull automatic sstem is thereore required to perorm all these operations. These unctions are ideall perormed b a PLC. Usuall PLC control oers maximum throughput, maximum ecienc, constant product, and minimizes startup and shutdown times. It also minimizes CIP time while maximizing CIP eectiveness. Most PLCs oer historical data collection so that management can continue to improve and maximize the evaporator sstem’s perormance.
51
Preassembled Evaporators Almost all small evaporators and certain medium size evaporators can be preassembled in the shop prior to shipment. The advantages o this approach are given below: •
•
•
Assembl o equipment, piping and wiring in the shop is easier and less expensive than assembl in the eld. The time to install the equipment in the eld is considerabl reduced. This reduces the disruption to other plant operation. The overall cost o the project is reduced.
A small preassembled Paravap evaporator (Figure 28) can be ull assembled on a stainless steel skid complete with control panel and motor starters. The on site installation takes hours rather than das. A larger sstem (Figure 29), like this double eect orced circulation sstem, was too large to ship as a single skid so it was assembled o two skids in the shop and partiall broken down or shipment. The maximum size o equipment that can be shipped over the roads is about 12t. (3.65m) b 14t. (4.25m) b 100t. (30m). However, it is still sti ll possible to preassemble preas semble large sstems in the shop. The sstems are then match marked and disassembled or shipment. Assembl on site is a relativel simple procedure. However, preassembl becomes less attractive economicall as the size o the sstems increases.
Figure 28 52
Figure 29
The Production o High Qualit Juice Concentrates Changes in our liestles over the past twent ears have been dramatic. Not the least o these changes has been our dietar habits — infuenced not onl b our perceived values o diet related to general health, but also b changes in ood processing technolog across a ver wide spectrum. Storage o ruit beore processing begins a gradual process o change rom the resh product. Breaking or peeling o ruit releases some o the natural essences even at atmospheric temperatures, and natural biochemical processes commence which aect color and enzme components, pectin and other characteristic properties o the ruit. The aim o ood manuacturers is to produce a juice or concentrate which closel resembles the original ‘resh rom the ruit’. O all the was we can infuence this, time and temperature are paramount. Evaporation
Evaporation is b ar the most prevalent process used or the production o concentrates. It provides a highl energ ecient means o removing water and is well suited to recovering ‘essence’ components during the process. The problem or the equipment designer has alwas been one o providing a costeective sstem having low energ requirements, with acceptable concentrate qualit, and along the wa collecting essences in sucientl useable quantit and qualit. The ultra short time FFPE (Falling Film Plate Evaporator) was introduced b APV in the earl 1970’s. The patent covered a two-plate per unit design — one steam and one product — in which the product could be ed rst to one hal o the plate then returned in series to the other side o the plate or improved wetting without recirculation.
53
The most dicult design area o an alling lm evaporator is the liquid distribution sstem which ensures an even fow o liquid over the total evaporating surace. This was achieved b an ingenious three stage process involving small pressure losses and fash vapor. Time/temperature are markedl infuenced b single pass operation in an evaporator b avoiding the use o recirculation. In the FFPE, with its two-stage design and longer fow path, recirculation is avoided on all triple eect and over sstems, and even on doubleeect under some temperature conditions. This design could still be improved, however, and the FFSR (Falling Film Long Evaporator) is the current development in the plate evaporator technolog. This is a divided plate design like the FFPE, but has a 50% longer fow path. This creates thinner lms o the plate, with improved wetting characteristics. A single alling lm plate eect, less than 78”/2 meters in plate length, is equivalent to one pass in a tube 630”/16 meters long. A special arrangement o the support pipes improves cleaning in place (CIP) o the plate, b using a disparate positioning on the plate. The FFLE is current state-o-the art technolog, producing concentrates o high qualit on a wide range o juices. Essence Recovery Distillation
Essences can be recovered b ull distillation techniques with high ield on products less sensitive to temperature, such as apple and grape. The distillation aroma recover process is described in the ollowing case stud, where its application in a special conguration on grape juice concentration combines a number o new technological eatures. Partial Condensation
The loss o, or damage to, essences rom ruit commences at the moment o picking. It increases ater extraction, and with an orm o heating and fash vapor release. The partial condensation aroma recover unit has provided eective and economic was o capturing the elusive favor components or storage and re-use with reconstituted juices or or use in the cosmetic and other industries.
54
The partial condensation aroma recover unit makes use o the act that i juice is heated in a closed sstem, then released into a region o pressure below the saturation point, fash vapors released will strip aroma compounds rom the liquid phase into volatiles which travel with the vapors. There will be be some essence components which do not volatalize and remain in the juice throughout the process, but a substantial percentage o the aromas is liberated. I the vapors rom the rst ‘strip’ are withdrawn rom the rst stage o evaporation in a multi-eect sstem, the will be more than enough in quantit to ensure a high percentage recover o aromas. These will go with the vapor to the heating side o the next evaporator eect to provide the energ or urther evaporation. In the process, onl part o the vapor is condensed. A portion, perhaps 10 or 15%, is allowed to pass through the heating side uncondensed, and then ducted to the aroma recover sstem. Because o the dierent boiling points o aroma compounds, most o the essences remain with the uncondensed portion. In the aroma recover unit, a urther selective condensing process takes place, which removes more o the water vapor to leave a concentrated essence. This essence is chilled and collected together with recovered components rom a nal vent scrubber sstem. It can then be stored or later use or added back to asepticall processed concentrate during the cooling stage. The temperature at which the rst strip takes place varies according to the ruit. Some tropical ruits, like pineapple, are move sensitive, and temperatures above 60°C should be avoided. For apple and less sensitive ruits, temperatures in the 80s or 90s can provide higher ields without thermal degradation o the essence. Case Study
Concord grape presents its own special problems in concentration due to the high level o tartrates. These tartrates can crstallize out under certain temperature and concentration conditions with unhapp results in terms o length o run between cleanings.
55
A team o distillation and evaporation specialists used new and existing technolog to develop a sstem to cope with these product characteristics and to produce qualit essences with high ield. The ke eatures o the nal solution chosen were as ollows: •
•
•
In order to keep temperatures above crstallization, the grape juice was concentrated using a reverse eed design, with dilute juice being directed to the low temperature eect rst and leaving at the high temperature eect (Figure 30). In order to provide the qualit enhancement and color benets specied, an FFLE was selected in a three, our or ve (Welch’s) (Welch’s) eect conguration. congurati on. This ensured the shortest possible residence time during the initial stages o concentration, where tartrate crstallization can be more readil controlled. A tubular nisher evaporator was selected, designed specicall to deal with the problem area where concentrate is approaching the supersaturation point or tartrates.
Figure 30. Flow diagram. Concord grape juice is extremel dicult to process due to the precipitation o tartrates during concentration. To To keep temperatures above crstallization, as the grape juice is concentrated, a reverse eed design was selected, with dilute juice being directed to the low temperature eect rst and leaving at the high temperature eect.
56
At the nisher level o concentration, it was no longer possible to operate at temperatures high enough to keep tartrates in solution. The designer thereore used the relativel larger eective diameter o a tube to advantage, b emploing a orced circulation mode operating at onl 120°F (50°C). This technique promoted larger crstal growth in the nal concentrate. Tartrate crstal growth occurs more on crstals in suspension instead o on equipment. This promotes longer runs between cleaning. The orced circulation tubular design was well able to cope with the crstals on extended operating times, and the larger crstals were much easier to deal with at the separation stage. A large distillation column was chosen to recover essences rom the grape juice. In the reverse eed sstem, most o the highl volatile essence components (methl anthranilate being the ke essence) were released in the initial stage o evaporation. When these condensates plus vents were taken into the column or stripping and rectication, a high ield o essence was guaranteed. The ke to the design was the use o essence-rich vapor discharge rom the distillation column, directl into the steam side o the rst eect FFLE, where it provided the total energ to drive the three- or our- eect preconcentrator evaporator using the evaporator as a condenser. The rst eect condensate now became the rich essence, and most o this was returned to the column as refux. A small quantit o essence was removed and chilled, and later this was added back to the concentrate or qualit enhancement. In terms o energ ecienc, this plant (Figure 31) was a breakthrough in design o high qualit concentrate-plus-essence sstems.
Figure 31 57
Engineering Conversions TO CONVERT FROM
TO
MULTIPLy By
Calories/(Gram) Calories/(Gram ) (Mole) (°C) BTU/(Pound) BTU/(Pound) (°F)
Molecular Weight 1.0
Pounds/Gallon Pounds/Cubic Ft.
8.33 62.42
Btu/(Hr) (Ft) (°F)
0.6719 0.5778
Centipoise
Speciic Gravit
Centipoise
1488.2
Centistokes
100
psi
0.14504 14.504 0.4912 14.696 0.01908 0.01908
Heat Capacit Calories/(Gram) Calories/(Gra m) (°C)
Densit Gram/Milliliter
Thermal Conductivit Kilocalorie/(Hr) Kilocalorie/(Hr) (m) (°C) Watt/(m) (°C)
Viscosit Centistokes
Dnamic Viscosit Pound-Mass/(Ft) Pound-Mass/(F t) (Sec)
Kinematic Viscosit Cm2/Sec
Pressure KiloPascal Bar Inches Hg Absolute Atmosphere Torr mm Hg
psia
Enthalp Calorie/Gram Work/Energ (Kilowatt) (Hr) (Horsepower) (Hr) Calorie
Btu/Pound-Mass
1.8
Btu
3412.1 2544.4 0.003968
Btu/(Hr)(Ft2)(°F)
0.2048 1761.1
Heat Transer Coeicient Kilocalorie/(Hr) (M 2) (°C) Watt/(cm 2)(°C)
58
Properties o Saturated S aturated Steam Temperature Tables TEMPERATURE °F
°C
32 33 34
PRESSURE PSIA
BAR
VACUUM In Hg
SPECIFIC VOLUME
LATENT HEAT
mm Hg
Ft3/lb
m3/Kg
Btu/lb Kcals/Kg
0.000 0.556 1.111
0.08859 0.00611 29.741 755.421 0.09223 0.00636 29.734 755.244 0.09600 0.00662 20.726 526.440
3304.7 3180.7 3061.9
206.544 198.794 191.369
1075.5 1074.9 1074.4
597.5 597.2 596.9
35 36 37 38 39
1.667 2.222 2.778 3.333 3.889
0.09991 0.10395 0.01815 0.11249 0.11698
0.00689 0.00717 0.00125 0.00776 0.00807
29.718 29.710 29.701 29.692 20.683
754.837 754.634 754.405 754.177 525.348
2948.1 2839.0 2734.4 2634.2 2538.0
184.256 177.438 170.900 164.638 158.625
1073.8 1073.2 1072.7 1072.1 1071.5
596.6 596.2 595.9 595.6 595.3
40 41 42 43 44
4.444 5.000 5.556 6.111 6.667
0.12163 0.12645 0.13143 0.13659 0.14192
0.00839 0.00872 0.00906 0.00942 0.00979
29.674 29.664 29.654 29.643 29.632
753.720 753.466 753.212 752.932 752.653
2445.8 2357.3 2274.4 2191.0 2112.8
152.863 147.331 142.150 136.938 132.050
1071.0 1070.4 1069.8 1069.3 1068.7
595.0 594.7 594.3 594.1 593.7
45 46 47 48 49
7.222 7.778 8.333 8.889 9.444
0.14744 0.15314 0.15904 0.16514 0.17144
0.01017 0.01056 0.01097 0.01139 0.01182
29.621 29.610 29.597 29.585 29.572
752.373 752.094 751.764 751.459 751.129
2037.8 1965.7 1896.5 1830.0 1766.2
127.363 122.856 118.531 114.375 110.388
1068.1 1067.6 1067.0 1066.4 1065.9
593.4 593.1 592.8 592.4 592.2
50 51 52 53 54
10.000 10.556 11.111 11.667 12.222
0.17796 0.18469 0.19165 0.19883 0.20625
0.01227 0.01274 0.01322 0.01371 0.01422
29.559 29.545 29.531 29.516 29.501
750.799 750.443 750.087 749.706 749.325
1704.8 1645.9 1589.2 1534.8 1482.4
106.550 102.869 99.325 95.925 92.650
1065.3 1064.7 1064.2 1063.6 1063.1
591.8 591.5 591.2 590.9 590.6
55 56 57 58 59
12.778 13.333 13.889 14.444 15.000
0.21392 0.22183 0.23000 0.23843 0.24713
0.01475 0.01530 0.01586 0.01644 0.01704
29.486 29.470 29.453 29.436 29.418
748.944 748.538 748.106 747.674 747.217
1432.0 1383.6 1337.0 1292.2 1249.1
89.500 86.475 83.563 80.763 78.069
1062.5 1061.9 1061.4 1060.8 1060.2
590.3 589.9 589.7 589.3 589.0
60 61 62 63 64
15.556 16.111 16.667 17.222 17.778
0.25611 0.26538 0.27494 0.28480 0.29497
0.01766 0.01830 0.01896 0.01964 0.02034
29.400 29.381 29.362 29.341 29.321
746.760 746.277 745.795 745.261 744.753
1207.6 1167.6 1129.2 1092.1 1056.5
75.475 72.975 70.575 68.256 66.031
1059.7 1059.1 1058.5 1058.0 1057.4
588.7 588.4 588.1 587.8 587.4
59
TEMPERATURE
60
PRESSURE
VACUUM
SPECIFIC VOLUME
LATENT HEAT
°F
°C
PSIA
BAR
In Hg
mm Hg
Ft3/lb
m3/Kg
Btu/lb Kcals/Kg
65 66 67 68 69
18.333 18.889 19.444 20.000 20.556
0.30545 0.31626 0.316 26 0.32740 0.32 740 0.33889 0.33 889 0.35073 0.35 073
0.02107 0.02181 0.02258 0.02337 0.02419
29.299 29.277 29.255 29.231 29.207
2.02062 2.01910 2.01759 2.01593 2.01428
1022.1 989.0 957.2 926.5 896.9
63.881 61.813 59.825 57.906 56.056
1056.9 1056.3 1055.7 1055.2 1054.6
587.2 586.8 586. 8 586.5 586. 5 586.2 586. 2 585.9 585. 9
70 71 72 73 74
21.111 21.667 22.222 22.778 23.333
0.36292 0.36 292 0.37549 0.3 7549 0.38844 0.3 8844 0.40177 0.4017 7 0.41550 0.4155 0
0.02503 0.02590 0.02679 0.02771 0.02866
29.182 29.157 29.130 29.103 29.075
2.01255 2.01083 2.00897 2.00710 2.00517
868.4 840.9 814.3 788.8 764.1
54.275 52.556 50.894 49.300 47.756
1054.0 1053.5 1052.9 1052.4 1051.8
585.6 585 .6 585.3 585 .3 584.9 584 .9 584.7 58 4.7 584.3 58 4.3
75 76 77 78 79
23.889 24.444 25.000 25.556 26.111
0.42964 0.4296 4 0.44420 0.444 20 0.45919 0.459 19 0.47461 0.474 61 0.49049 0.490 49
0.02963 0.03063 0.03167 0.03273 0.03383
29.027 29.017 28.986 28.955 28.923
2.00186 2.00117 1.99903 1.99690 1.99469
740.3 717.4 695.2 673.9 653.2
46.269 44.838 43.450 42.119 40.825
1051.2 1050.7 1050.1 1049.5 1049.0
584.0 58 4.0 583.7 583. 7 583.4 583. 4 583.1 583. 1 582.8 582. 8
80 81 82 83 84
26.667 27.222 27.778 28.333 28.889
0.50683 0.50 683 0.52364 0.52 364 0.54093 0.54 093 0.55872 0.5 5872 0.57702 0.5 7702
0.03495 0.03611 0.03731 0.03853 0.03979
28.889 28.855 28.820 28.784 28.746
1.99234 1.99000 1.98759 1.98510 1.98248
633.3 614.1 595.6 577.6 560.3
39.581 38.381 37.225 36.100 35.019
1048.3 1047.8 1047.3 1046.7 1046.1
582.4 582. 4 582.1 582. 1 581.8 581 .8 581.5 581 .5 581.2 581 .2
85 86 87 88 89
29.444 30.000 30.556 31.111 31.667
0.59583 0.5 9583 0.61518 0.6151 8 0.63507 0.6350 7 0.65551 0.6555 1 0.67653 0.676 53
0.04109 0.04243 0.04380 0.04521 0.04666
28.708 28.669 28.628 28.587 28.544
1.97986 1.97717 1.97434 1.97152 1.96855
543.6 527.5 511.9 496.8 432.2
33.975 32.969 31.994 31.050 27.013
1045.6 1045.0 1044.4 1043.9 1043.3
580.9 580 .9 580.6 58 0.6 580.2 58 0.2 579.9 579. 9 579.6 579. 6
90 91 92 93 94
32.222 32.778 33.333 33.889 34.444
0.69813 0.698 13 0.72032 0.720 32 0.74313 0.74 313 0.76655 0.76 655 0.79062 0.79 062
0.04815 0.04968 0.05125 0.05287 0.05453
28.500 28.455 28.408 28.361 28.312
1.96552 1.96241 1.95917 1.95593 1.95255
468.1 454.5 441.3 428.6 416.3
29.256 28.406 27.581 26.788 26.019
1042.7 1042.2 1041.6 1041.0 1040.5
579.3 579. 3 579.0 579. 0 578.7 578. 7 578.3 578. 3 578.1 578. 1
95 96 97 98 99
35.000 35.556 36.111 36.667 37.222
0.81534 0.81 534 0.84072 0.8 4072 0.86679 0.8 6679 0.89356 0.8935 6 0.92103 0.9210 3
0.05623 0.05798 0.05978 0.06162 0.06352
28.261 28.210 28.157 28.102 28.046
1.94903 1.94552 1.94186 1.93807 1.93421
404.4 392.9 381.7 370.9 360.5
25.275 24.556 23.856 23.181 22.531
1039.9 1039.3 1038.8 1038.2 1037.6
577.7 577 .7 577.4 577 .4 577.1 577 .1 576.8 576 .8 576.4 57 6.4
TEMPERATURE
PRESSURE
VACUUM
SPECIFIC VOLUME
LATENT HEAT
°F
°C
PSIA
BAR
In Hg
mm Hg
Ft3/lb
m3/Kg
Btu/lb Kcals/Kg
100 101 102 103 104
37.778 38.333 38.889 39.444 40.000
0.94924 0. 94924 0.97818 0 .97818 1.00789 1 .00789 1.03838 1 .03838 1.06965
0.06546 0.06746 0.06951 0.07161 0.07377
27.989 27.930 27.869 27.807 27.743
1.93028 1.92621 1.92200 1.91772 1.91331
350.4 340.6 331.1 322.0 313.1
21.900 21.288 20.694 20.125 19.569
1037.1 1036.5 1035.9 1035.4 1034.8
576.2 575.8 575.5 575.2 574.9
105 106 107 108 109
40.556 41.111 41.667 42.222 42.778
1.10174 1.1347 1.1684 1.2030 1.2385
0.07598 0.07826 0.08058 0.08297 0.08541
27.678 27.611 27.542 27.417 27.400
1.90883 1.90421 1.89945 1.89083 1.88966
304.5 296.18 288.11 280.30 272.72
19.031 18.511 18.007 17.519 17.045
1034.2 1033.6 1033.1 1032.5 1031.9
574.6 574.2 573.9 573.6 573.3
110 111 112 113 114
43.333 43.889 44.444 45.000 45.556
1.2750 1.3123 1.3505 1.3898 1.4299
0.08793 0.09050 0.09314 0.09585 0.09861
27.325 27.249 27.172 27.092 27.001
1.88448 1.87924 1.87393 1.86841 1.86214
265.39 258.28 251.38 244.70 238.22
16.587 16.143 15.711 15.294 14.889
1031.4 1030.8 1030.2 1029.6 1029.1
573.0 572.7 572.3 572.0 571.7
115 116 117 118 119
46.111 46.667 47.222 47.778 48.333
1.4711 1.5133 1.5566 1.6009 1.6463
0.10146 0.10437 0.10735 0.11041 0.11354
26.926 26.840 26.752 26.662 26.569
1.85697 1.85103 1.84497 1.83876 1.83234
231.94 225.85 219.94 214.21 208.66
14.496 14.116 13.746 13.388 13.041
1028.5 1027.9 1027.3 1026.8 1026.2
571.4 571.1 570.7 570.4 570.1
120 121 122 123 124
48.889 49.444 50.000 50.556 51.111
1.6927 1.7403 1.7891 1.8390 1.8901
0.11674 0.12002 0.12339 0.12683 0.13035
26.475 26.378 26.279 26.177 26.073
1.82586 1.81917 1.81234 1.80531 1.79814
203.26 198.03 192.95 188.03 183.24
12.704 12.377 12.059 11.752 11.453
1025.6 1025.0 1024.5 1023.9 1023.3
569.8 569.4 569.2 568.8 568.5
125 126 127 128 129
51.667 52.222 52.778 53.333 53.889
1.9428 1.9959 2.0507 2.1068 2.1642
0.13399 0.13765 0.14143 0.14530 0.14926
25.966 25.858 25.746 25.632 25.515
1.79076 1.78331 1.77559 1.76772 1.75966
178.60 174.09 169.72 165.47 161.34
11.163 10.881 10.608 10.342 10.084
1022.7 1022.2 1021.6 1021.0 1020.4
568.2 567.9 567.6 567.2 566.9
130 131 132 133 134
54.444 55.000 55.556 56.111 56.667
2.2230 2.2830 2.3445 2.4074 2.4717
0.15331 0.15745 0.16169 0.16603 0.17046
25.395 25.273 25.148 25.020 24.889
1.75138 1.74297 1.73434 1.72552 1.71648
157.33 153.44 149.66 145.98 142.41
9.833 9.590 9.354 9.124 8.901
1019.8 1019.3 1018.7 1018.1 1017.5
566.6 566.3 565.9 565.6 565.3
61
TEMPERATURE
62
PRESSURE
VACUUM
SPECIFIC VOLUME
LATENT HEAT
°F
°C
PSIA
BAR
In Hg
mm Hg
Ft3/lb
m3/Kg
Btu/lb Kcals/Kg
135 136 137 138 139
57.222 57.778 58.333 58.889 58.88 9 59.444
2.5375 2.6047 2.6735 2.7438 2.8157
0.17500 0.17963 0.18438 0.18923 0.19419
24.755 24.618 24.478 24.335 24.188
628.78 625.30 621.74 618.11 614.38
138.94 135.57 132.29 129.11 126.01
8.684 8.473 8.268 8.069 7.876
1016.9 1016.4 1015.8 1015.2 1014.6
564.9 564.7 564.3 564.0 563.7
140 141 142 143 144
60.000 60.556 61.111 61.667 62.222 62.22 2
2.8892 2.9643 3.0411 3.1195 3.1997
0.19926 0.20443 0.20973 0.21514 0.22067
24.039 24.886 23.730 23.570 23.407
610.59 606.70 602.74 598.68 594.54
123.00 120.07 117.22 114.45 111.76
7.688 7.504 7.326 7.153 6.985
1014.0 1013.4 1012.9 1012.3 1011.7
563.3 563.0 562.7 562.4 562.1
145 146 147 148 149
62.778 63.333 63.889 64.444 65.000
3.2816 3.3653 3.4508 3.5381 3.6273
0.22632 0.23209 0.23799 0.24401 0.25016
23.240 23.069 22.895 22.718 22.536
590.30 585.95 581.53 577.04 572.41
109.14 106.59 104.11 101.70 99.35
6.821 6.662 6.507 6.356 6.209
1011.1 1010.5 1009.9 1009.3 1008.7
561.7 561.4 561.1 560.7 560.4
150 151 152 153 154
65.556 66.111 66.667 67.222 67.778
3.7184 3.8114 3.9065 4.0035 4.1025
0.25644 0.26286 0.26941 0.27610 0.28293
22.351 22.161 21.968 21.770 21.569
567.72 562.89 557.99 552.96 547.85
97.07 94.84 92.68 90.57 88.52
6.067 5.928 5.793 5.661 5.533
1008.2 1007.6 1007.0 1006.4 1005.8
560.1 559.8 559.4 559.1 558.8
155 156 157 158 159
68.333 68.889 69.444 70.000 70.556
4.2036 4.3068 4.4122 4.5197 4.6294
0.28990 0.29702 0.30429 0.31170 0.31927
21.363 21.153 20.938 20.719 20.496
542.62 537.29 531.83 526.26 520.60
86.52 84.57 82.68 80.83 79.04
5.408 5.286 5.168 5.052 4.940
1005.2 1004.6 1004.0 1003.4 1002.8
558.4 558.1 557.8 557.4 557.1
160 161 162 163 164
71.111 71.667 72.222 72.778 73.333
4.7414 4.8556 4.9722 5.0911 5.2124
0.32699 0.33487 0.34291 0.35111 0.35948
20.268 20.035 19.798 19.556 19.309
514.81 508.89 502.87 496.72 490.45
77.29 75.58 73.92 72.30 70.72
4.831 4.724 4.620 4.519 4.420
1002.2 1001.6 1001.0 1000.4 999.8
556.8 556.4 556.1 555.8 555.4
165 166 167 168 169
73.889 74.444 75.000 75.556 76.111
5.3361 5.4623 5.5911 5.7223 5.8562
0.36801 0.37671 0.38559 0.39464 0.40388
19.057 18.800 18.538 18.271 17.998
484.05 477.52 470.87 464.08 457.15
69.18 67.68 66.22 64.80 63.41
4.324 4.230 4.139 4.050 3.963
999.2 998.6 998.0 997.4 996.8
555.1 554.8 554.4 554.1 553.8
TEMPERATURE
PRESSURE
VACUUM
SPECIFIC VOLUME
LATENT HEAT
°F
°C
PSIA
BAR
In Hg
mm Hg
Ft3/lb
m3/Kg
Btu/lb Kcals/Kg
170 171 172 173 174
76.667 77.222 77.778 78.333 78.889
5.9926 6.1318 6.2736 6.4182 6.5656
0.41328 0.42288 0.43266 0.44263 0.45280
17.720 17.437 17.148 16.854 16.554
1.22207 1.20255 1.18262 1.16234 1.14166
62.06 60.74 59.45 58.19 56.97
3.879 3.796 3.716 3.637 3.561
996.2 998.6 998.0 997.4 996.8
553.4 554.8 554.4 554.1 553.8
175 176 177 178 179
79.444 80.000 80.556 81.111 81.667
6.7159 6.8690 7.0250 7.1840 7.3460
0.46317 0.47372 0.48448 0.49545 0.50662
16.248 15.936 15.618 15.295 14.965
1.12055 1.09903 1.07710 1.05483 1.03207
55.77 54.61 53.47 52.36 51.28
3.486 3.413 3.342 3.273 3.205
996.2 995.6 995.0 994.4 993.8
553.4 553.1 552.8 552.4 552.1
180 181 182 183 184
82.222 82.778 83.333 83.889 84.444
7.5110 7.679 7.850 8.025 8.203
0.51800 0.52959 0.54138 0.55345 0.56572
14.629 14.287 13.939 13.582 13.220
1.00890 0.98531 0.96131 0.93669 0.91172
50.225 49.194 48.189 47.207 46.249
3.139 3.075 3.012 2.950 2.891
993.2 992.6 992.0 991.4 990.8
551.8 551.4 551.1 550.8 550.4
185 186 187 188 189
85.000 85.556 86.111 86.667 87.222
8.384 8.568 8.756 8.947 9.141
0.57821 0.59090 0.60386 0.61703 0.63041
12.851 12.477 12.094 11.705 11.310
0.88628 0.86048 0.83407 0.80724 0.78000
45.313 44.400 43.508 42.638 41.787
2.832 2.775 2.719 2.665 2.612
990.2 989.6 989.0 988.4 987.8
550.1 549.8 549.4 549.1 548.8
190 191 192 193 194
87.778 88.333 88.889 89.444 90.000
9.340 9.541 9.747 9.956 0.168
0.64414 10.905 0.75207 0.65800 10.496 0.72386 0.67221 10.076 0.69490 0.68662 9.651 0.66559 0.70124 9.219 0.63579
40.957 40.146 39.354 38.580 37.824
2.560 2.509 2.460 2.411 2.364
987.1 986.5 985.9 985.3 984.7
548.4 548.1 547.7 547.4 547.1
195 196 197 198 199
90.556 91.111 91.667 92.222 92.778
10.385 10.605 10.830 11.058 11.290
0.71621 0.73138 0.74690 0.76262 0.77862
8.777 8.329 7.871 7.407 6.935
0.60531 0.57441 0.54283 0.51083 0.47828
37.086 36.364 35.659 34.970 34.297
2.318 2.273 2.229 2.186 2.144
984.1 983.5 982.8 982.2 981.6
546.7 546.4 546.0 545.7 545.3
200 201 202 203 204
93.333 93.889 94.444 95.000 95.556
11.526 11.766 12.011 12.259 12.512
0.79490 0.81145 0.82834 0.84545 0.86290
6.454 5.966 5.467 4.962 4.447
0.44510 0.41145 0.37703 0.34221 0.30669
33.639 32.996 32.367 31.752 31.151
2.102 2.062 2.023 1.985 1.947
981.0 980.4 979.7 979.1 978.5
545.0 544.7 544.3 543.9 543.6
63
TEMPERATURE
64
PRESSURE
VACUUM
SPECIFIC VOLUME
LATENT HEAT
°F
°C
PSIA
BAR
In Hg
mm Hg
Ft3/lb
m3/Kg
Btu/lb Kcals/Kg
205 206 207 208 209
96.111 96.667 97.222 97.778 98.333
12.782 13.043 13.310 13.581 13.856
0.88128 0.89928 0.91968 0.93637 0.95533
3.9296 3.3723 2.8301 2.2783 1.7184
99.8097 84.6551 71.8838 57.8690 43.6474
30.564 29.989 29.428 28.878 28.341
1.910 1.874 1.839 1.805 1.771
974.7 974.1 973.5 972.8 972.2
541.5 541.2 540.8 540.4 540.1
210 211 212
98.889 99.444 100.000
14.136 0.97464 1.1483 29.1672 14.421 0.99439 0.5681 14.4285 14.700 1.01351
27.816 27.302 26.799
1.739 1.706 1.675
971.6 970.9 970.3
539.8 539.4 539.1
213 214 215 216
100.556 101.111 101.667 102.222
15.003 15.302 15.606 15.915
1.03442 1.05504 1.07599 1.09730
26.307 25.826 25.355 24.894
1.644 1.614 1.585 1.556
969.7 969.0 968.4 967.8
538.7 538.3 538.0 537.7
220 224 228 232 236
104.444 106.667 108.889 111.111 113.333
17.201 18.591 20.031 21.583 23.233
1.18597 1.28043 1.38109 1.48810 1.60186
23.148 21.545 20.037 18.718 17.471
1.447 1.347 1.252 1.170 1.092
965.2 962.6 960.0 957.4 954.8
536.2 534.8 533.3 531.9 530.4
240 244 248 252 256
115.556 117.778 120.000 122.222 124.444
24.985 26.844 28.814 30.901 33.110
1.72266 1.85083 1.98666 2.13054 2.28283
16.321 15.260 14.281 13.375 12.538
1.020 0.954 0.893 0.836 0.784
952.1 949.5 946.8 944.1 941.4
528.9 527.5 526.0 524.5 523.0
260 264 268 272 276
126.667 128.889 131.111 133.333 135.556
35.445 37.913 40.518 43.267 46.165
2.44385 2.61009 2.79362 2.98315 3.18296
11.762 11.042 10.375 9.755 9.180
0.735 0.690 0.648 0.610 0.574
938.6 935.9 933.1 930.3 927.5
521.4 519.9 518.4 516.8 515.3
280 284 288 292 296
137.778 140.000 142.222 144.444 146.667
49.218 52.431 55.812 59.366 63.100
3.39346 3.61499 3.84810 4.09314 4.35059
8.6439 8.1453 7.6807 7.2475 6.8433
0.540 0.509 0.480 0.453 0.428
924.6 921.7 918.8 915.9 913.0
513.7 512.1 510.4 508.8 507.2
TEMPERATURE
PRESSURE
°F
°C
PSIA
BAR
300 304 308 312 316
148.889 151.111 153.333 155.556 157.778
67.005 71.119 75.433 79.953 84.668
320 324 328 332 336
160.000 162.222 164.444 166.667 168.889
340 344 348 352 356
VACUUM In Hg
mm Hg
SPECIFIC VOLUME
LATENT HEAT
Ft3/lb
m3/Kg
Btu/lb Kcals/Kg
4.62103 4.90476 5.20228 5.51400 5.83917
6.4658 6.1130 5.7830 5.4742 5.1849
0.404 0.382 0.361 0.342 0.324
910.0 907.0 904.0 901.0 897.9
505.6 503.9 502.2 500.6 498.8
89.643 94.826 100.245 105.907 111.820
6.18228 6.53972 6.91345 7.30393 7.71172
4.9138 4.6595 4.4208 4.1966 3.9859
0.307 0.291 0.276 0.262 0.249
894.8 891.6 888.5 885.3 882.1
497.1 495.3 493.6 491.8 490.1
171.111 173.333 175.556 177.778 180.000
117.992 124.430 131.142 138.138 145.424
8.13738 8.58138 9.04428 9.52676 10.02924
3.7878 3.6013 3.4258 3.2603 3.1044
0.237 0.225 0.214 0.204 0.194
878.8 875.5 872.2 868.9 865.5
488.2 486.4 484.6 482.7 480.8
360 364 368 372 376
182.222 184.444 186.667 188.889 191.111
153.010 160.903 169.113 177.648 186.517
10.55241 11.09676 11.66297 12.25159 12.86324
2.9573 2.8184 2.6873 2.5633 2.4462
0.185 0.176 0.168 0.160 0.153
862.1 858.6 855.1 851.6 848.1
478.9 477.0 475.1 473.1 471.2
380 384 388 392 396
193.333 195.556 197.778 200.000 202.222
195.729 205.294 215.220 225.516 236.193
13.49855 14.15821 14.84276 15.55283 16.28917
2.3353 2.2304 2.1311 2.0369 1.9477
0.146 0.139 0.133 0.127 0.122
844.5 840.8 837.2 833.4 829.7
469.2 467.1 465.1 463.0 460.9
65
Notes:
66
Notes:
67
your local contact:
APV, An SPX APV, S PX Brand 105 CrossPoint Parkwa Getzville, Ny 14068 Phone: (716) 692-3000 (800) 207-2708 Fax: (716) 692-1715 E-mail:
[email protected] For more inormation about our worldwide locations, approvals, certications, and local representatives, please visit www.apv www.apv.com. .com. SPX reserves the right to incorporate our latest design and material changes without notice or obligation. Design eatures, materials o construction and dimensional data, as described in this bulletin, are provided or our inormation onl and should not be relied upon unless conrmed in writing.
Issued: 02/2009 10003-01-08-2008-US
Copright © 2008 SPX Corporation
