HYDROGEN PEROXIDE
CHAPTER 1: INTRODUCTION
Hydrogen peroxide (H 2O2) is a very pale blue liquid which appears colorless in a dilute solution, slightly more viscous than water. It is a weak acid. acid. It has strong oxidizing properties and is therefore a powerful bleaching agent that is mostly used for bleaching paper, but has also found use as a disinfectant, a disinfectant, as as an oxidizer, and oxidizer, and as a propellant for rockets. As simple as it may seem, the treatment of contaminated waters is as diverse and complicated as the operations from which it comes. In today's environment, where merely transferring contaminants from one medium to another is no longer acceptable, it is no surprise that a powerful oxidizer that looks like water -- in its appearance, chemical formula and reaction products -- should be so widely used. This is hydrogen peroxide (H 2O2) -- a powerful yet versatile oxidant that is both safe and effective.
Fig.1 H2O2 Bonding [2]
1.1 History
In the years following discovery of hydrogen peroxide in laboratory in 1818, four processes have made the chemical available commercially first fi rst to be commercialized
6
HYDROGEN PEROXIDE
was chemistry related to the laboratory discovery route: reacting barium peroxide with sulfuric acid to produce hydrogen peroxide and barium sulfate. A few decades after the first commercial process was introduce, electrolytic processes were developed and placed in operation. Variation of electrolytic routes appeared as economic improvements and proprietary position were sought. Plants were built in many locations throughout the world, supplying product to relatively small market radii until the last of the last of the larger electrolytic plants was shut down in 1983. The third process to manufacturing hydrogen peroxide is the overwhelmingly predominant commercial process in use in the 1980s, other processes having been shut down over a period of years as economics dictated. The widely used process is based on the non-catalyzed oxidation of alkyl anthrahydroquinone, often oft en commonly referred to as the quinine process for hydrogen peroxide. Before further explanation of the quinine process, the fourth commercial process for producing hydrogen hydrogen peroxide should be listed. Principal chemistry of this process was oxidizing iso-propanol to produce hydrogen peroxide (by product) and acetone .The only plant built with this process operated until 1980, in the era when the advantage of the quinine process was accelerating, and a number of electrolytic plants were still operating. About 50% of the world's production of hydrogen peroxide in 1994 was used for pulp- and paper-bleaching. Other major industrial applications for hydrogen peroxide include the manufacture of sodium percarbonate and sodium perforate, perforate, used as mild bleaches in laundry detergents. It detergents. It is used in the production of certain organic certain organic peroxides such as dibenzoyl as dibenzoyl peroxide, used peroxide, used in polymerisation in polymerisation and other chemical processes. Hydrogen peroxide is also used in the production of epoxides epoxides such as propylene as propylene oxide. New industrial and home applications may be developed with the discovery of a catalytic reaction using powdered precious metal-based catalyst, hydrogen peroxide and methyl alcohol. A small plastic bottle incorporating these can produce superheated steam in one to two seconds releasing only CO2 and high temperature steam for a variety of purposes.
7
HYDROGEN PEROXIDE
CHAPTER 2: LITERATURE SURVEY 2.1 Reactions
Principal reactions in the quinine process for hydrogen peroxide are as follows: Oxidation Hydroquinone + oxygen Quinine + hydrogen peroxide
(2.1)
Hydrogenation Catalyst
Quinone + Hydrogen
Hydroquinone
(2.2)
Conditions of a commercial process require that a third reaction group be added to the oxidation and hydrogenation, namely: By-product reactions
Quinone derived by product Hydroquino Hydroquinone Quinone
(2.3)
Quinone- derived by -products can be subdivided into three categories:
1. Adjust by-products which produce hydrogen peroxide in hydrogenation /oxidation as in equations (2.1) and (2.2). Tetraquinone (Tetrahydroalkylanthraquinone) is the only adjunct by-product. 2. Regeneration by-products which do not produce hydrogen peroxide and which may be converted in high yield to useful quinine or tetraquinone. Epoxide is the most prominent of by-product. by-product. 3. Degraded by-products which do not produce hydrogen peroxide and which may be converted at low yield or not at all to useful quinines.[3] quinines.[3]
Paths and mechanisms for by-product reactions are not clearly defined. In some by product reactions re actions there may be b e a reactant such as hydrogen or oxygen in addition to the organic molecule. In other case, movement of the labile hydrogen may define a by product. In cases where careful work has been done to isolate and identify quinine8
HYDROGEN PEROXIDE
derived by-products in commercial systems, the possibility exists that some compounds isolated had parentage in quinine-like impurities introduced with commercial purity raw material quinine.
Oxidation
Quinone Hydrogen peroxide ( 2.4) Hydrogen Oxigen Tetrahydroquinone Tetraquino ne
Hydroquino Hydroquinone
Hydrogenation
Hydroquinone Hydroquino Catalyst Hydrogen Hydrogen Tetraquinone Tetrahydro quinone Quninone
(2.5)
By-product Reactions
Qunone derived by-products (2.6) Hydroquino Hydroquinone, Tetraquinone Quinone, Tetraquinone
Heats of reaction are moderately high exothermic for both hydrogenation and oxidation. [2]
9
HYDROGEN PEROXIDE
2.2 Manufacturers of Hydrogen Peroxide
Shrenuj Dye-Chem. Ahmedabad, Gujarat
Vishal Enterprises. Chennai, Tamil Nadu
Pallav chemical & solvent pvt. Ltd. Mumbai, Maharashtra
Gujarat Alkali & Chemical Ltd. Vadodara, Gujarat
Orbit Texchem Private Ltd. Surat, Gujarat
Kor Chem Ltd. Ankleshwer, Gujarat
Meru Chem Industries. Mumbai, Maharashtra
Dharani Export-Import Services (p) Ltd. Chennai, Tamil Nadu
Shakambari Enterprises India Private Ltd. Nagpur, M.P.
10
HYDROGEN PEROXIDE
CHAPTER 3: PROCESS SELECTION & DESCRIPTION 3.1 Types of Processes 3.1.1 Catalytic H 2O2
The more difficult-to-oxidize pollutants may require the H 2O2 to be activated with catalysts such as iron, copper, manganese, or other transition metal compounds. These catalysts may also be used to speed up H 2O2 reactions that may otherwise take hours or days to complete. H 2O2 catalysis may occur either in solution (using soluble catalysts) or in packed columns (using solid catalysts).[1] 3.1.2 Solution Catalysis
The most commonly used solution catalyst is iron, which when used with H 2O2 is referred to as Fenton's Reagent. The reaction requires a slightly acidic pH and results in the formation of highly reactive hydroxyl radicals (-OH) which are capable of degrading most organic pollutants. Another solution catalyst is copper, which is often used to destroy cyanides. Other metals also show catalytic activity with H 2O2 and may be used to selectively destroy specific pollutants.[1] 3.1.3 Advanced Oxidation Processes (AOP's)
Hydrogen peroxide is manufactured today almost exclusively by the autoxidation of 2-ethyl-9,10-dihydroxyanthracene 2-ethyl-9,10-dihydroxy anthracene (C 16H14O2) to 2-ethylanthraquinone (C 16H12O2) and hydrogen peroxide using oxygen from the air. In this reaction, the hydroxy groups on the middle ring of anthracene anthracene are deprotonated and are turned into ketones, into ketones, while while two double bonds are lost from the middle ring and are replaced as C=O double bonds in the ketone groups. The anthraquinone derivative is then extracted out and reduced back to the dihydroxy compound using hydrogen gas in the presence of a metal catalyst. The catalyst. The overall equation for the process is deceptivel y simple: H2 + O2 → H2O2
11
HYDROGEN PEROXIDE
However the economics of the process depend on effective recycling of the quinone and extraction solvents, and of the hydrogenation the hydrogenation catalyst. catalyst.[1] [1] 3.2 Selected Process
In the above-mentioned processes the Advanced Oxidation Process is most widely used at present in the world .this process has the raw materials of Hydrogen, oxygen, quinone, solvent. This process is selected because it gives high conversion compared to other processes also raw material is cheaper and easily available in the market without fluctuations. This process also gives the high purity of product. Considering the situation of our country & its economy, I would like to select the above, most widely used process because of the following reasons. (A) Raw material hydrogen, oxygen, quinine, solvent is available in plenty of quantity in the market. (B) Consideration of the application of advanced technology, the high quality of product is achieved by this process. (C) It is cheaper process as compared to other processes. (D) This method of production of Hydrogen peroxide is widely used almost in the world.[3]
3.2.1 Raw Materials
Hydrogen
Hydrogen from any of a variety of sources is suitable as a raw material if certain purity standers are met. Its assay can be well below 100% since the hydrogenation reaction effectively captures hydrogen values from the feed gas. High assay feed hydrogen is most commonly used since it is not particularly difficult to achieve, benefits hydrogenator design to some extend, and minimizes purging non- reactant gas components from the system. Carbon dioxide and hydrogen are inert in the hydrogenation reaction and are vented unused. Hydrogen purity must be very high with respect to carbon monoxide, which is a virulent poison for palladium catalyst. Contamination by carbon monoxide manifests itself when its concentration is above a bove 1 ppm. If monoxide concentration rises to 12
HYDROGEN PEROXIDE
several parts per million even briefly, hydrogenation activity declines abruptly. Catalyst poisoned by carbon monoxide can be restored to activity by restoring feed hydrogen purity or by the more arduous route of processing catalyst through the catalyst regeneration cycle. Sulfur in sulfide from is a hydrogenation catalyst poison but is seldom encountered in hydrogen sources feasible for the peroxide process.
Oxygen (Air)
A process air compressor is often considered a process auxiliary rather than a utility. The compressor feeding raw material air feed to oxidizer is the largest energy user in the process. Only sufficient air is fed to oxidize all hydroquinone in the oxidation step, but a moderate excess may be used. An advantageous compressor design allows for energy consumption turndown commensurate with air rate turndown to keep energy cost of this unit proportional to hydrogen peroxide production. Air need not be dessicated or specially cleaned beyond filtering before feeding to the oxidizer. Standard inter-stage and after coolers on the air compressor suffice to condense moisture from ambient air. Through de-entrainment of this condensate is necessary. A fume-free air source is required. A contaminant-free source of air must be regarded seriously during operation and even in selecting a plant site.
Quinone
High purity quinone is necessary both for making the initial working solution inventory and for ongoing makeup. Impurities in feedstock quinone may be of the degraded by-product class (refer to prior definitions) or of a class which suppresses hydrogenation activity. If impurities are of the degraded by-product class, they impose an unnecessary and unwanted load on the purge system for quinone-like by products. Metals and chlorides are other impurities which must be prevented from entering the process via any raw material, particularly quinone.
13
HYDROGEN PEROXIDE
Solvents Polar solvents are usually specialized raw materials whose quality
factors have been developed by cooperation between the hydrogen peroxide process company and the solvent manufacturer. High purity is characteristic. Nonpolar solvents are most often items of commerce commer ce whose quality factors are monitored by the peroxide process company. Several of these solvents are mixtures of several compounds, so composition is usually not monitored one the solvent is established as satisfactory for use.
14
HYDROGEN PEROXIDE Hydrogenator
Activated Carbon Absorber
Catalyst filter
Anthraquinone+ Solvent
For Further Treament
r e s i d i x O
Hydrogen
Degasser
Air or Oxygen Rich Air
Vacuum Column I Vacuum Column II
Water Recycle Liquid Liquid Extractor
Reflux
Surge Drum
Thermosyphon Shell & Tube Reboiler
Solvent Purification
Water recycle to Extrator Solvent Recycle
Make-up Water Feed
72% Hydrogen Peroxide Product
Fig. 3.1 Advanced Oxidation Process Flow Diagram
15
HYDROGEN PEROXIDE
3.2.2 Basic Reactions
(3.2)
(3.3)
Overall Reaction:
H2 + O2 → H2O2
Hydroquinone reactant in the upper reaction is a product in the lower reaction; quinine reactant in the lower reaction is a product in the upper reaction. Hydrogen peroxide is removed from the process chemistry circuit by water water extraction.
3.2.3 Working Solution
Chemistry of the system is conducted in an organic solution, commonly called working solution, which carries the quinine/ hydroquinone through oxidation and hydrogenation reactions and through the extraction step. The working solution is contained within the process for the entire life of the plant, being replaced only slowly by makeup for purges purges and losses. Pure quinine, pure hydroquinone, and related species are solids at ambient temperature, but working solution composition is selected so solubility limits of the
1
HYDROGEN PEROXIDE
solids in the solvents are not exceeded. The organic solution is homogeneous at all times, with no solid or liquid second phase, at all points in t he commercial process.
Working solution is composed of: Non-polar solvent acting primarily to dissolve the oxidized from of quinine and tetraquinone. Polar solvent acting primaritl to dissolved the hydrogenated from of quinine and tetraquinone. Quinone/ tetraquinone Unwanted but unavoidable quinine-related species.
For the quinine member of working solution, processes have used one or a mixture of: 2-Ethyl anthraquinone, 2-Tertiary butyl anthraquinone & 2-Amyl anthraquinone
For the nonpolar solvent member, one or mixture of the following has been used: Benzene, Mixed alkyl naphthalenes, mixed alkyl benzene, Particular alkyl benzenes
For the polar solvent member, one or a mixture of the following has been used: Trioctylphosphate, Diisobutyl carbniol, Methyl cyclohexyl acetate, Tetraalkyl urea
In general, by using only one member from each group-quinone, nonpolar solvent practical working solutions are formulated. However, mix tures of members from each group have been used. Hence, there are a large number of operable working solutions. Even through commercial processes have operated for more than 30 years, a single dominant working solution composition has not established itself. There are 8-10 principal compositions among those favored by various peroxide manufacturers. Though two plants may starts with the same composition, process history-excursions from normal conditions, etc.-influences the working solution composition and the plants will have different solution compositions after a period of time.
2
HYDROGEN PEROXIDE
Working Solution Properties:
The process steps described thus far have been commercialized around working solution which displays the following properties: 1.
High solubility‟s for the hydrogenated and oxidized states of solids which are
dissolved in the solvents. 2. The solvents resist reaction in the process steps. 3. The organics are soluble in aqueous phase to the lowest possible degree. 4. The solution density is less than that of water. Solutions heavier than the process aqueous phase are not barred but have not been commercialized. 5. The distribution coefficient of hydrogen peroxide favors the aqueous phase when in contact with the working solution.
This list could be extended to include the matters of cost, flammability properties, and toxicity.
3.2.4 Catalyst Options
Another element in Eq. is the hydrogenation catalyst. Palladium as the catalytic material is widely used. Closely allied to the catalyst and the type of hydrogenator in which the catalyst is used. Thus, adding to the list of option for practical working solution are the following choices in the hydrogenation step, where can be used with most working solutions.
Palladium on catalyst support; slurry catalyst hydrogenator Palladium on catalyst support; fixed-bed catalyst hydrogenator Unsupported Palladium; slurry catalyst hydrogenator h ydrogenator Activated alumina is used widely, but not exclusively, for catalyst supports, both for slurry type and fixed-bed type catalysts.
3.2.5 Process Description
Oxidation Step
Hydrogen peroxide is first formed in the oxidation step, a gas-liquid contactor. various designs are in use, usually columns. Air is used as the oxygen source.
3
HYDROGEN PEROXIDE
Economic evaluations as well as safety considerations indicate pure oxygen ism not competitive with air. The oxidation step is designed to utilize 70-92% of the oxygen in the incoming air. Oxygen partial pressure and working solution residence time in the steps are principal variables which influence design. Residence time usually ranges from 10 to 40 min. Pressure is usually 1 atm gauge or higher. Where energy costs are high, economics usually favors the lower end of the pressure range to minimize energy for compressing the large volume of air. Offsetting lower air compression energy costs at low pressure are the larger size of the oxidation reactor and the accompanying larer investment in working solution which is inventoried in reactor. Another factor affecting oxidation step design is the ratio of anther to tetraquinone in the working solution. High anthrax/tetra ratio solutions have faster oxidation rates but slower hydrogenation rates than low anthrax/ tetra solutions. High anthrax/tetra ratio reduces the total cost of the oxidation step but imposes the tradeoff of less favorable conditions in the hydrogenation step. The anthrax/tetra ratio changes only a small amount in the 2-4 h transit time for working solution to circulate once around the reaction route. Well over 90% of the hydroquinone fed to oxidation is oxidized in the step. Only hydroquinone converted to hydrogen peroxide is available for extraction and net production from the process; any unoxidized hydroquinone passes with the working solution through the extraction step and into hydrogenation where it joins newly-made hydroquinone.
Extraction
Hydrogen peroxide, having been formed by the oxidation reaction and dissolve in the working solution, passes to the extraction step. Between oxidation and extraction, hydrogen peroxide concentration in the working solution is in the range 0.8-0.9 wt.%. in the extractor, a distributed coefficient favorable to the aqueous phase in contact with the working solution allow hydrogen peroxide to be extracted at concentration from 25 to 45 wt.% in the extract phase. Efficient extractors deplete the working solution of more than 95% of its hydrogen peroxide. Any peroxide remaining in the raffinate working solution is destroyed destro yed by subsequent process conditions, thus making efficient extraction imperative for good overall process economics.
4
HYDROGEN PEROXIDE
Extraction of hydrogen peroxide from the working solution into the aqueous phase is most commonly done in countercurrent sieves plate liquid-liquid extraction column. Compact centrifugal extractors may have reached commercial plant installation but have not found widespread favor, and may have been discontinued in use. Knowledge of distribution coefficients and mass transfer effects in the working solution /aqueous system is necessary to design the extraction column. One interesting aspect of column design is the considerable change in extract phase density from top to bottom of the column. At the top of the column, extract density is near 1.00 g/ml
(water at operating temperature commonly about 50‟C). At the bottom of the column, extract density corresponds to the concentration of Hydrogen peroxide. Raffinate density does not change appreciably from top to the bottom of the column. The working solution is usually the dispersed phase in a column-type extractor. Coalescence of the up-rising working solution droplets is allowed under each plate in a plate-column design. These strata of coalesced working solution may be 25-100mm thick, governed by the free area of the particular plate and the density different between the phases at that region of the column. Good phase separation is vital for good extractor performance. Mechanical and chemical means may be used to enhance both phase separation and droplet coalescence. At the top of the column where working solution coalesces before leaving the unit, it is useful to de-entrain as possible from the existing raffinate. Slurry catalyst may be suspended in the reactor inventory of working solution by some means of agitation, mechanical or gas. Hydrogenated working solution leaves the reactor through filters immersed in the vessel or associated with the main reactor vessel. The principal working solution flow rate is in the range 30-50 times as large as aqueous flow rate in a typical system. Conversely, aqueous residence time in a column may be 50-70 times as long as working solution residence.
Hydrogenation
Equipment in the hydrogenation step is the most complex in the process. Three prominent design principles pri nciples in the hydrogenation are (1) to provide for a high degree of hydrogen utilization, upwards of 90% and approaching 100%, (2) to retain
5
HYDROGEN PEROXIDE
hydrogenation catalyst within the reaction step, and (3) to be compatible with catalyst properties. Hydrogen gas is usually a prominent cost item; hence high yield is sought in making hydrogen peroxide from this raw material. Hydrogen will be completely consumed by reaction with quinine in a reaction time of 1-5 min at the usual reaction conditions. Hence, design is practical to react hydrogen to completion in one pass through the reactor, leaving little hydrogen to escape. System to recover and recirculate unreacted hydrogen can be used although they are not necessary on reactors designed to consume all the gas fed. Design features of the hydrogenation step must also retain the long-lived catalyst for ongoing use within the step. Fixed-bed catalyst reactors inherently retain catalyst within the system while passing reactors through the catalyst. In this respect, fixed-bed catalyst reactors commend themselves to the process. However, with respect to establishing advantageous overall reaction conditions in working solution systems, fixed-bed hydrogenations have proven complex. Unwanted side reactions occur in fixed-bed units, and this type of reactor has not found overwhelming favor despite its deceptive simplicity and appropriateness. Hydrogenators for slurry-type catalyst can be of many different designs to satisfy the aforementioned principals which apply to both supported and unsupported catalysts. In one type of reactor, all the principles can be satisfied in a single vessel hydrogenator. Hydrogen gas solution and residence time can be sufficient to reacpurpose of these filters is to retain catalyst within the reactor. Catalyst collected at the filter medium be released periodically to rejoin the slurry in the hydrogenator. Some manner of filter reverse flush is commonly c ommonly used for this purpose. In other configurations of the hydrogenation step, the reaction function and catalystretaining filtration function may be more distinctly separated than in the single vessel design. The hydrogenation must accommodate catalyst properties, particularly with respect to attrition resistance. Catalyst-retaining filter medium and catalyst filtration properties are matched so only tracers of catalyst exist from a slurry hydrogenator.
6
HYDROGEN PEROXIDE
3.2.6 Augmenting Process Functions
The three principal process steps in flow sheet – oxidation, oxidation, hydrogenation, must be augmented by other process functions and supported by a variety of auxiliary operations.
Catalyst Particle Barrier
Even though catalyst retention function is design into the hydrogenation step, a catalyst particle barrier is used in the main working solution stream to assure that no catalyst particles pass to the oxidation step. Hydrogenation catalyst appearing in the oxidizer will decompose hydrogen peroxide as soon as the peroxide is created by the oxidation reaction. Filtration of the highest efficiency is commonly used for the catalyst particle barrier. More than one stage of filtration may be used to assure a high degree of integrity to the barrier.
Degassing
The working solution entrains and dissolvers air when leaving the gas-liquid contractor oxidizer, and an air de-entrainment device is installed between the oxidizer and extractor in the main working solution stream. Entrained gas must be removed from the working solution so gas bubbles do not enter the liquid-liquid extractor and disturb interfaces, droplet formation, and droplet coalescence in the extraction column. Gas bubbles of very small diameter, as well as larger bubbles, must be dealt with in the design of an effective air de-entrainment device.
Water Control
Since the working solution is thoroughly contacted with water in the extractor, a water control function is imposed on the system. The water control function in fig. removes entrained water from the main working solution stream after it leaves the extractor and also reduces the water concentration below saturation in the stream. Complete dessication of the working solution is not necessary in the water control function since the hydrogenation reaction must have a particular concentration of water in the
7
HYDROGEN PEROXIDE
working solution in order to proceed. The exact role of water in hydrogenation is not well understood but it is universally recognized to be necessar y. A unit such as a separator is often used to remove entrains water, and second unit, such as a vacuum flash tank, is used to reduce the water concentration below saturation in the solution. Operating controls for the temperature and the flash tank vacuum set the desired water concentration in the working solution and catalyst pair requires a specific water concentration for optimum hydrogenation; each pair does not have the same optimum.
Working Solution Regeneration Regeneration
Working solution regeneration embodies a number of phenomena. One is to counteract or in fact reverse unwanted side reaction involving anthrax-and tetraquinones. In these types of reactions, quinine-related species, which have been rendered incapable of making hydrogen peroxide, are reverted to useful quinines or tetraquinones. Another phenomenon is to dehydrogenate tetraquinone to the anthrax form. Some processes use a working solution regeneration step which accentuates the dehydrogenation in order to maintain the composition of the process working solution inventory high in the anthra form of quinone. Other processes use a regeneration step in which tetra-to-anthra dehydrogenation is somewhat incidental but which nonetheless plays a role in setting the anthra/tetra ratio in the working solution inventory. Another phenomenon occurring in the regeneration step is unwanted side reactions of quinone species. Desirable effects of regeneration can predominate over undesirable effects by choosing suitable operating inventory. One working solution regeneration treatment is to pass a side-stream of working solution over a material such as activated alumina which is both absorbent and selectively catalytic for many chemical reactions. The absorbency function is a fourth phenomenon occurring in this type of regeneration. Selective absorbency of the regenerator catalyst removes irreversibly degraded quinone by-products from the solution. As shown in fig., the working solution regeneration function is fed a side-stream which branches from and returns to the main reaction circuit either before or after the
8
HYDROGEN PEROXIDE
hydrogenation step. The four phenomena described previously in this selection occur to different degrees in the regenerator, depending on the feed source of the working solution. Regeneration steps can be used which do not employ a catalyst adsorbent, but these types of regeneration are used in only a small number of commercial processes.
3.2.7 Auxiliary Operations
Catalyst Processing
Catalyst processing and preparation may be closely affiliated with the main process or these operations may be at separate plants or with vendors who specialize in catalysts. These options are true for fixed-bed and both types of slurry catalysts. The decision is usually of a make-or-buy nature since the peroxide process inherently neither mandates close-coupled catalyst processing nor favors off-site processing. Both reprocessed catalysts taken from the hydrogenator and newly made, never used catalyst must be considered. All catalysts are stable, and shelf-life is not a problem when a catalyst is not in use. Fixed-bed catalyst is usually operated to the end of its useful life, perhaps a few years with the aid of periodic revivifications in place. The supply of catalyst for changing a fixed bed can be made in large amounts over a short period of time or in small amounts which are stockpiled. Slurry catalysts have an inherent advantage over fixed-bed catalysts in being amenable to periodic removal and replacement in small amounts in the system. Some types of slurry catalyst removed from the system are completely remade as if starting from virgin ingredients. Other slurry catalysts can be regenerated through hundreds of cycles of use and regeneration without remaking the basic catalyst. In all cases the valuable palladium or precious metal is diligently pursued to remake/regenerate into an active catalyst. Catalyst preparation procedures are closely guarded. Supported palladium catalysts have precious metal content from 0.3 to 2.0% by weight. The exact supports used, conditioning of the support, deposition of the palladium, and postdeposition conditioning figure in making selective catalysts.
9
HYDROGEN PEROXIDE
Working Solution Makeup
Working solution makeup is another auxiliary unit necessary for ongoing plant operation. Working solution raw materials-quinone and solvent must be introduced periodically to maintain steady working solution composition and inventory. Quinone is dissolved in the solvent or in an aliquot of working solution before being introduced to the main working solution inventory. The dissolver vessel is usually sized to handle the one time operation of making the entire system working solution inventory. However, these facilities are often used to make the entire system inventory just prior to commissioning the plant. The makeup quinone solution is usually filtered to insure the cleanest possible state before introducing it to the main system which has exceptionally efficient filters. Makeup solvent may be pumped directly to the system through guard filters or through the filter in the solution makeup equipment.
Solvent Recovery, Oxidizer Exit Air
Recovering solvent from the oxidizer column exhaust air is necessary for economic and environmental reasons. The exhaust air is saturated with working solution and water vapor. The fractional percentage of water concentration in the working solution contributes a significant amount of vapor to the
air exhaust because water‟s volatility
is substantially greater than the next most volatile component. Condensers coupled with mist eliminators are used to recover much of the condensable solvent/water mixture. Low-temperature condensers, again coupled with mist eliminators, may be used for an adequate final cleanup by running at a condensate temperature of 2-5‟C. Through cleaning of the exhaust air is achieved by absorbing the solvent/water vapor on activated carbon in a rather straightforward application of adsorbent technology.
When using adsorbent technology it is necessary to recognize the absorbed solvent‟s low volatility so adequate provision is made for desorption. Exceptionally through deentrainment is needed on the absorber feed gas (oxidizer exhaust air) so that working solution droplets do not reach the adsorbent and progressively diminish the adsorbent capacity.Solvent recovered from the oxidizer exhaust air is returned to the main body of the working solution composition.
10
HYDROGEN PEROXIDE
Oxidizer Air Feed
A process air compressor is often considered a process auxiliary rather than a utility. The compressor feeding raw material air feed to oxidizer is the largest energy user in the process. Only sufficient air is fed to oxidize all hydroquinone in the oxidation step, but a moderate excess may be used. An advantageous compressor design allows for energy consumption turndown commensurate with air rate turndown to keep energy coasts of this unit proportional to hydrogen peroxide production. Air need not be dessicated or specially cleaned beyond filtering before feeding to the oxidizer. Standard interstage and after coolers on the air compressor suffice to condense moisture from ambient air. Through de-entrainment of this condensate is necessary. A fume-free air source is required. A contaminant-free source of air must be regarded seriously during operation and even in selecting a plant site.
Water Purification
Deionized water with a resistivity of at least 10^6 Ω/cm is required to feed the extractor and any other process points to the solutions of hydrogen peroxide. Sometimes pure water is available from some other process on a common site; more often the hydrogen peroxide plant creates the need for pure water. Industry stander water treatments are used to purity the source water to the purity needed in the peroxide process. The purification sequence is designed to remove virtually all contaminants, including silica. The water purification system often has a capacity more than triple the process flow sheet requirement because large amounts of high purity water are used to wash shipping containers and for other utilitarian purposes.
Hydrogen Peroxide Product
After synthesis, hydrogen peroxide solution is usually clarified and stabilized, and it is often concentrated to strengths higher than the extract strength. Clarification to remove a tracer of haze in the solution is achieved by a combination of filtration and solvent contact. Stabilization employs certain chemicals, usually inorganic, to suppress peroxide decomposition created by tracers of contaminants from commercial processes. Peroxide is usually concentrated in fractional distillation apparatus. [3]
11
HYDROGEN PEROXIDE
CHAPTER 4: PHYSICAL & CHEMICAL PROPERTIES
4.1 Physical Properties
Table 4.1: Properties and Values of Hydrogen Peroxide PROPERTY
VALUE
Melting point / oc
-0.41
Boiling point / oc
150.2
Density at 25oc / g ml-1
1.4425
Viscosity at 20oc / mpa s
1.245
Surface tension at 20oc / mn m-1
80.4
Specific conductance at 25oc / Ω.cm
4 x 10-7
Enthalpy of fusion / J g -1
367.52
Specific heat at 25oc / J g-1
2.628
Heat of vaporization at 25oc / J g-1
1517
Heat of dissociation / kj mol-1
34.3
4.2 Chemical Properties Properties
H2O2 is one of the most powerful oxidizers known -- stronger than chlorine, than chlorine, chlorine chlorine dioxide, and dioxide, and potassium potassium permanganate. And permanganate. And through catalysis, H 2O2 can be converted into hydroxyl radicals (.OH) with reactivity second only to fluorine.
12
HYDROGEN PEROXIDE
Table 4.2: Various Oxidants and Oxidation Potentials Oxidant
Oxidation potential, V
Fluorine
3.0
Hydroxyl radical
2.8
Ozone
2.1
Hydrogen peroxide
1.8
Potassium permanganate
1.7
Chlorine dioxide
1.5
Chlorine
1.4
Hydrogen peroxide can decompose spontaneously into water and oxygen. It usually acts as an an oxidizing agent, agent, but there are many reactions where it acts as a reducing agent, agent, releasing oxygen as a by-product. It also readily forms both inorganic and organic peroxides. organic peroxides. 4.2.1 Decomposition
Hydrogen peroxide always decomposes (disproportionate) exothermically into into water and oxygen and oxygen gas spontaneously: gas spontaneously: 2 H2O2 → 2 H2O + O2
This process is very favorable; it has a
−1 Δ H o of −98.2 kJ·mol kJ·mol and a ΔGo of
−119.2 kJ·mol−1 and a ΔS of 70.5 J·mol−1·K −1. The rate of decomposition is dependent on the temperature and concentration of the peroxide, as w ell as the pH the pH and the presence of impurities and stabilizers. Hydrogen peroxide is incompatible with many substances that catalyze its decomposition, including most of the transition metals and their compounds. Common catalysts include manganese dioxide, dioxide, and silver. silver. The same reaction is catalysed by the enzyme catalase, catalase, found in the liver, whose main function in the body is the removal of toxic byproducts of metabolism and the reduction of oxidative stress. stress. The decomposition occurs more rapidly in alkali, so alkali, so acid acid is often added as a stabilizer.
13
HYDROGEN PEROXIDE
The liberation of oxygen and energy in the decomposition has dangerous side effects. Spilling high concentration peroxide on a flammable substance can cause an immediate fire, which is further fueled by the oxygen released by the decomposing hydrogen peroxide. High-strength peroxide (also called high-test peroxide or HTP) must be stored in a suitable, vented container to prevent the buildup of oxygen gas, which would otherwise lead to the eventual rupture of the container. In the presence of certain catalysts, such as Fe2+ or Ti 3+, the decomposition may take a different path, with free radicals such as HO- (hydroxyl) and (hydroxyl) and HOO- being formed. A combination of H 2O2 and Fe2+ is known as Fenton's as Fenton's reagent. 4.2.2 Alkalinity
Hydrogen peroxide is a much weaker base than water, but it can still form adducts with very strong acids. The super The super acid HF/SbF acid HF/SbF5 forms unstable compounds containing the [H3O2] + ion. [1,2,4]
14
HYDROGEN PEROXIDE
CHAPTER 5: MATERIAL BALANCE
Basis: 10000 tons per year of hydrogen peroxide production and 320 working days.
Therefore, Production of hydrogen peroxide per day
=
=
10000 x1000 320
31250 kg/day
So, total requirement of hydrogen peroxide is 31250 kg/day. Molecular weight of hydrogen peroxide is 34 kg/kg-mole. So, total requirement of hydrogen peroxide is 919.117 kg-moles.
5.1 Raw Material Requirement
Chemical reactions: For hydrogenation:
C14H8O2
+
H2 C14H10O2
Data:
Molecular weight of Quinone: 208.28 kg/kg-mole kg/kg-mole Molecular weight of Hydroquinone: Hydroquinone: 210.23 kg/kg-mole Molecular weight of Hydrogen: Hydrogen: 2 kg/kg-mole kg/kg-mole Molecular weight of Oxygen: Oxygen: 32 kg/kg-mole kg/kg-mole Molecular weight of Hydrogen Peroxide: 34 kg/kg-mole
So, requirement of quinone:
210.23 kg of hydroquinone
= 208.28 kg of quinone
193226.10 kg of hydroquinone =
193226.10 x 208.28 210
15
HYDROGEN PEROXIDE
= 191433.82 kg of quinone.
= 919.117 kg-mol
Now, requirement of hydrogen; hydrogen;
210.23 kg of hydroquinone
= 2 kg of hydrogen
193226.10 kg of hydroquinone =
193226.10 x 2 210.23
= 1838.23 kg of hydrogen.
= 919.115 kg-mol. For, Oxidation;
C14H10O2
+
O2
C14H8O2
+
H2O2
Now, requirement of hydroquinone: hydroquinone:
34 kg of hydrogen peroxide
= 210.23 kg of hydroquinone
31250 kg of hydrogen peroxide =
31250 x 210.23 34
= 193226.10 kg of hydroquino h ydroquinone. ne. = 919.117 kg-mol.
Last, requirement of oxygen: 34 kg of hydrogen peroxide
= 32 kg of oxygen
31250 kg of hydrogen peroxide
=
31250 x 32 34
= 29411.76 kg of oxygen. = 919.117 kg-mol.
16
HYDROGEN PEROXIDE
5.2 Material Balance over Hydrogenation Unit
Quinone
Hydroquinone
Hydrogenator 191433.82 kg
193226.10 kg
Hydrogen 1838.23 kg
Fig. 5.1 Material Balance over Hydrogenator Unit
Total In = 191433.82 + 1838.23 = 193226.10 kg Total Out = 193226.10 kg So, Total In = Total Out
Input in Hydrogenator: Quinone = 191433.82 kg Hydrogen = 1838.23 kg
Output from Hydrogenator: Hydroquinone = 193226.10 (Working solution) Table 5.1: Material Balance over Hydrogenator
Material In
Amount(kg)
Material Out
Amount(kg)
Quinone
191433.82
Hydroquinone
193226.10
Hydrogen
1838.23
17
HYDROGEN PEROXIDE
5.3 Material Balance over Oxidation Unit
Hydroquinone
Working solution Oxidation Unit
193226.10 kg
222637.86 kg
Oxygen 29411.76 kg
Fig. 5.2 Material Balance over Oxidation Unit
Total In = 193226.10 + 29411.76 = 222637.86 kg Total Out = 222637.86 kg So, Total In = Total Out
Input in Oxidation Unit Hydroquinone= 193226.10 kg Oxygen = 29411.76 kg (Air)
Output from Oxidation Unit Working solution= 222637.86 kg
Table 5.2: Material Balance over Oxidation Unit
Material In
Amount(kg)
Material Out
Amount(kg)
Hydroquinone
193226.10
Working solution
222637.86
Oxygen
29411.76
18
HYDROGEN PEROXIDE
5.4 Material Balance over Extraction Unit
Water 45.96 kg Hydrogen peroxide Working Solution 222637.86 kg
Extractor
31250 kg
Quinone 191433.82 kg
Fig. 5.3 Material Balance over Extraction Unit
Total In = 222637.86 + 45.96= 222683.82 kg Total Out = 31250 + 191433.82 = 222683.82 kg So, Total In = Total Out
Input in extractor: Working solution=222637.86 kg Water =45.96 kg
Output from extractor: Hydrogen peroxide = 31250 kg Quinone = 191432.82 kg
Table 5.3: Material Balance over Extractor Material In
Amount(kg)
Material Out
Amount(kg)
Working Solution
222637.86
Hydrogen peroxide
31250
Water
45.96
Quinone
191433.82
19
HYDROGEN PEROXIDE
CHAPTER 6: THERMODYNAMICS AND REACTION KINETICS Principal reactions in the quinine process for hydrogen h ydrogen peroxide are as follows: Hydrogenation Catalyst
Quinone + Hydrogen
Hydroquinone
C14H8O2 + H2 C14H8O2
[1]
Oxidation
Hydroquinone + oxygen Quinine + hydrogen peroxide
C14H10O2 + O2 C14H8O2 + H2O2
[2]
The rate equations will be given as follows:
Subscripts
R1γ = ργ K1 NC14H8O2 NH2 (-E1/RTγ)
[1]
R2γ = ργ K2 NC14H10O2 NO2 (-E2/RTγ)
[2]
C14H8O2,
H 2,
C14H10O2 and
hydroquinone hydroquinone and oxygen ox ygen respectively.
20
O2 represent
Quinone,
hydrogen,
HYDROGEN PEROXIDE
CHAPTER 7: ENERGY BALANCE
Basis: Production of 10000 tons per year of hydrogen peroxide and 320 working days.
Production of hydrogen peroxide is 31250 kg/day.
Normal temperature: 25 ˚C ~ 298˚K Base temperature: 29˚ C ~ 302 ˚K 7.1 Thermodynamic Data
Table 7.1: Thermodynamic data
COMPOUND MOLECULAR No. of moles
Hf ˚ AT 25˚C
CP kg/kmol
WT.
n
KJ/MOL
˚K
C14H8O2
280.28
919.12
-496.749
47.56
H2
2
919.115
0
33.94
C14H10O2
210.23
919.117
-536.764
25.89
O2
32
919.117
0
23.70
H2O2
34
919.117
-187.86
67.34
H2O
18
2.55
-285.83
33.56
Here, Cp= (a+bT+cT2+dT3)
Energy balance with first reaction:
C14H8O2 C14H8O2 + H2 Now,
Heat of reaction= [∆H˚f (prod.) - ∆H˚f (react)] = [(-536.764)-(-496.749)] = -40.015 kJ
21
HYDROGEN PEROXIDE
Heat absorbed or relies by each compound: For, the first reaction
Reactant (C14H8O2):
Q= nCp∆T = (919.12 x 45.56 x 4) = 167500.428 kJ
Reactant (H2):
Q= nCp∆T = (919.115 x 33.94 x 4) = 124779.05 kJ
Product (C14H10O2):
Q= nCp∆T = (919.117 x 25.89 x 4) = 95183.76 kJ
Energy balance with second reaction:
C14H8O2 + H2O2 C14H10O2 + O2 Now,
Heat of reaction= [∆H˚f (prod.) - ∆H˚f (react)] = [{(-496.749) + (-187.86)}] – [-536.764] [-536.764] = -147.845 kJ
22
HYDROGEN PEROXIDE
Heat absorbed or relies by each compound: For second reaction:
Reactant (C14H10O2):
Q= nCp∆T = 919.117 x 25.89 x 4 = 95183.76 kJ
Reactant (O2):
Q= nCp∆T = 919.117 x 23.70 x 4 = 87132.29 kJ
Product (C14H8O2):
Q= nCp∆T = (919.12 x 45.56 x 4) = 167500.428 kJ
Product (H2O2):
Q= nCp∆T = 919.117 x 67.34 x 4 = 247573.355 kJ Product (H2O):
Q= nCp∆T = 2.55 x 33.56 x4 = 342.312 kJ
23
HYDROGEN PEROXIDE
7.2 Energy Balance over Hydrogenation Unit
Amount of heat added -197095.718
Quinone
167500.428
Hydroquinone
HYDROGE NATOR
95183.76
Hydrogen 124779.05
Energy Input in hydrogenation unit:
Quinone: 167500.428 kJ Hydrogen: 124779.05 kJ
Energy out from hydrogenation unit: Hydroquinone: 95183.76 kJ
Amount of heat added in hydrogenation unit: 197095.718 kJ
Table 7.2 Energy Balance over Hydrogenator Material In
Amount(kJ)
Material Out
Amount(kJ)
Quinone
167500.428
Hydroquinone
95183.76
Hydrogen
124779.05
Heat
-197095.718
24
HYDROGEN PEROXIDE
7.3 Energy Balance over Oxidation Unit
Hydroquinone 95183.76
Working solution OXIDATION UNIT
182316.05 Oxygen 87132.29
Energy Input in oxidation unit:
Hydroquinone: 95183.76 kJ Oxygen: 87132.29 kJ
Energy out from hydrogenation unit:
Working solution: 182316.05 kJ
Amount of heat relies in i n hydrogenation unit: - 232415.421 kJ
Table 7.3 Energy Balance over Oxidation Unit Material In
Amount(kJ)
Material Out
Amount(kJ)
Hydroquinone
95183.76
Working solution
95183.76
Oxygen
87132.29
25
HYDROGEN PEROXIDE
7.4 Energy Balance over Extraction Unit
Working solution 182316.05
Water 342.312 Hydrogen peroxide 247573.355
EXTRACTION UNIT
Quinone 167500.483
Energy Input in extraction unit:
Working solution: 182316.05 kJ Water: 342.312 kJ
Energy out from hydrogenation unit:
Hydrogen peroxide: 247573.355 kJ Quinone: 167500.483 kJ
Table 7.4 Energy Balance over Extractor Material In
Amount(kJ)
Material Out
Amount(kJ)
Working solution
182316.05
Hydrogen peroxide
247573.355
Water
342.312
Quinone
167500.483
26
HYDROGEN PEROXIDE
CHAPTER 8: PROCESS EQUIPMENT DESIGN 8.1 Hydrogenator Design
In the manufacturing of Hydrogen peroxide, hydrogenator is used. In this type of reactor reactants are added to the vessel and the product is removed after completion of process. The design of reaction vessel contains the design of the shell, head, flanges, nozzles and bolts. The calculations are as follows: 191433.82
Liquid flow rate =
24
= 7976.40 kg/hour. Gas flow rate=
1838.23 24
= 76.59 kg/hour.
8.1.1 Design of Shell
Capacity of the reactor is 8 tones and it is filled up to 2/3 height of the vessel. So the volume of reactor is 9000 liter. Data Reactor volume (V)
: 9000 liter
Diameter of shell (Di)
: 1200 mm
Radius of shell(R)
: 600 mm
Internal pressure
: 0.101 N/ (mm) 2
Internal design pressure (p) : 0.101+0.03 = 0.131 N/ (mm)
2
Permissible design stress (f) : 130 N/ (mm) 2 (at 125° C) Density of steel (ς)
: 7820 kg/ m3
Calculation Height of shell (H) =
Thickness (ts) =
V R
2
=
9000 3.14 0.6
2
p Di 2 f J p
27
= 7961.78 mm = 8000 8000 mm
HYDROGEN PEROXIDE
=
0.131 1200
2 130 0.85 0.131
= 0.71 mm For rigidity minimum thickness of 4 mm is used. (no corrosion allowance.)
Weight of the vessel (W) = Vς = r 2 r 1 H 2
ς
= 0.01608 7820 =150kg The stresses created due to combined loadings can be st ated as: 1. Tensile stress in the circumferential direction due to internal pressure f t= =
p Di t
2 t 0.131 1200 4 2 4
=19.71 N/ (mm)
2
2. Tensile Stress in the longitudinal direction due to internal pressure f 1= =
p Di
4 t 0.131 1200 4 4
=9.82 N/ (mm)
2
3. Compressive stress in longitudinal direction due to weight of vessel & contents. f 2 =
=
W
t Di t
8000 150 9.8 4 1204
=5.278 N/ (mm)
2
4. No wind load f 3 =0 f a (tensile)=f 1+f 2 28
HYDROGEN PEROXIDE
=9.82+5.278 =15.098 N/ (mm) 2
5. Stress due to offset piping wind Torque due to offset piping= 500 N*mm. f s =
=
2 T
t Di Di t 2 500 1000
4 1200 1204
=0.05 N/ (mm) 2
Tensile equivalent stress
f R f t f t f a f a 3 f s R = 2
2
2
0.5
= 19.722 19.72 15.098 15.0982 3 0.052 = 17.86 N/ (mm)
0.5
2
f R f a both are less than the permissible tensile stress. R and
8.1.2 Design of Head
The internal design pressure is 0.131 N / mm2 and for this pressure torispherical dished head can use. Torispherical head have the dish or crown radius equal to or less than the diameter of the head. To reduce the stress at corner of the head, a knuckle is formed with a radius of at least 6% of inside diameter.
Data Radius of head= 1200 mm Crown radius (R c) =1200 mm Stress identification factor (W) =
1 3 Rc 4 R1
1 1200 = 3 4 72
29
HYDROGEN PEROXIDE
= 1.77 Thickness of head p RC W
t h
2 f J
0.131 1200 1.77
2 130 1
= 1.07 mm Use 4mm thickness of head (no corrosion allowance)
8.1.3 Design of Half Coil Jacket
Data Diameter of half coil (d1) = 100 mm Design pressure (P) = 0.35 N/ mm 2 Allowable stress (f c) = 98 N/ mm 2
Calculation Thickness of half coil
t C
P d 1
2 f c 0.35 100 2 98
=0.17 mm So use 3 mm thick plate. Circumferential stress in the shell
P Di P Di 2 4 2 . 5 t s t c t s
F ps =
0.101 1200 0.35 100 2 4 4 3 2.5 4 =16.7 N/mm2
Longitudinal stress in the shell at the junction of the coil
30
HYDROGEN PEROXIDE
P Di P Di 2 P d o 2 f as 2 4 t s 4 t s 3 t s 2 2 0.249 104 0.131 1200 0.35 100 2 2 4 4 4 2 3
=63.65 N/mm 2 This is less than the allowable stress str ess value of 98 N/mm2.
8.1.4 Design of Nozzle Reinforcement
Data Internal diameter= 150 mm Internal design pressure= 0.131 N/mm 2
Calculation Minimum nozzle thickness t n
P Di
2 f J P 0.131 131 150
2 130 1 0.131
Maximum horizontal distance for compensation
2 150 = 300 mm
Maximum vertical distance for compensation
6 2.66 =15.96 mm
Area of compensation
150 2.66 = 400 mm 2
Area of compensation provided by head A s d t s t s ' , where ts =original thickness
31
HYDROGEN PEROXIDE
ts‟=theoretical thickness A s 150 4 0.71
=493.5 mm 2
Area of compensation provided by nozzle A0 2 H 1 t n t n '
2 2.5 3 3 0.07 = 44 mm2 The nozzle does not project inside vessel, H 2=0 A1= 0 Total area compensation = 537.5 mm 2 This is satisfactory, therefore no additional compensation required.
8.1.5 Design of Agitator
It is more preferred to buy Philadelphia agitator, which give lower power consumption and better mixing.
Type of agitator = turbine agitator
Straight blade type having insulation for protecting against corrosion
Diameter of agitator = 1/3 x 1200 = 400 mm
Maximum speed = 120 rpm
Internal pressure = 0.88 N/mm 2
Liquid in vessel specific gravity = 1.161
Viscosity, μ = 600 cp - more excess than process liquid
Thickness of blade = 1/5 x 400 = 80 mm
No of blade = 4
Shaft material = Cold rolled steel
Permissible stress in a shaft = 55 N/mm2
Elastic limit in tension = 246 N/mm 2
Modulus of Elasticity = 19.5 x 10 4 N/mm2
Permissible stress for key
MOC = CS 32
HYDROGEN PEROXIDE 2
Shear = 65 N/mm
Crushing = - 30 N/mm 2
Stuffing box = CS
Permissible stress = 58.7 N/mm2
Baffle width = Di/12 = 1200/12 = 100 mm
Baffle Height = 2.5 x 400 = 1000 mm
Offset = 1/5 width = 20 mm
Location of Agitator:
Height from bottom > Diameter of Agitator, Da
Total liquid Height = 5.3 m
Total tank height = 8 m
Submerging of agitator = 4 to 6
Taking submerging = 5 x 400 = 2000 mm
Height from bottom = 1250 mm
Total shaft overhang = Total height -1250 + 20 above vessel = 6770 mm
Power required of agitator,
Nre = ρ N Da2/μ = 1.161 x 1000 x 120 x 400 2 x 1000/(60 x 600 x 10 6) = 619.23 from power curve, Np = 3.8
P = Np x ρ x N 3 x Da5/(gc x 75) = 2.16 Hp
Gland loss = 10% of P = 0.216 Hp 33
HYDROGEN PEROXIDE
Transmission loss = 20 % = 0.432 Hp
Total Hp = 2.808 Hp Take 3 Hp considering fitting losses and done calculation.
Shaft design:-
Continuous average rated torque on shaft
T = Hp x 750 x 60/ (2лN) = 3 x 750 x 60/ (2л x 120) = 179.140 Nm
Tmax = 1.5 T = 268.710 Nm Now fs = Tmax/ Zp Where, fs = Permissible shear stress Zp = Polar Modulus of shaft section
Zp = Tmax/ fs = 268.710 x 1000/55 = 48.85 cm3
d3 = 16 x Zp/л
= 16 x 48.85/ л d = 29.19 cm
Now torque Tmax is resisted by a force Fm acting at a radius radius of 0.75 R b from the axis of the agitator shaft. Fm = Tmax/ (0.75 R b) Where, Rb = radius of blade Fm = 268.710/ (0.75 x 0.2)
34
HYDROGEN PEROXIDE
=1791.4 N The maximum bending moment occurs at a point near bearing, M = Fm x l Where, L = shaft overhang M = 1791.4 x 6.67 = 11948.638 Nm
The equivalent bending moment is given by, Me = ½ [M + (M + Tmax) 1/2 = ½ [11948.638 + (11948.638 + 268.710) 1/2] = 6029.58 Nm
The stress due equivalent bending moment, f = Me/Z where, Z = Modulus of section
= л d3/32 f = 6029.58 x 32 x 1000/ (л x 400 3) = 960.12 N/mm 2 Here f> 246 N/mm2 Use 8 cm diameter shaft We get f = 120.01 N/mm 2 Now deflection of shaft,
Δ = WL3/ (3 x E x I) Where, W = concentrated load L = Appropriate length
I = moment of inertia = л x d 4 /64 Δ = 3222.82 x 6770 3 x 64/ (3 x 19.5 x 10 6 x л x 84) = 4.506 cm The critical speed is calculated as Nc = 60 x 4.987/ (4.506) (4.506) 1/2 = 140.95 rpm 35
HYDROGEN PEROXIDE
which is 85.13 % of max. speed
8.2 Design of Storage Tank
Production of hydrogen peroxide is 31250 kg/day.
Volume of the storage tank: 350 m 3
8.2.1 Volume of shell
V=
π D2 H 4
We have D: H = 8:3 So, D = 8 H 3 V = π x 8 H 2 H 4
3
350 = π x 64 x H 3 4
9
H=3.97 4 m
D = 10.59 m.
≈11 m 8.2.2 Thickness of shell: ts = PD + CA 2fJ Where, P = (H – 0.3) – 0.3) x ρ fluid x g / gc = (4 – 0.3) 0.3) x 1450 x 10 = 53650 N/ m 2 =0.053650 N/ mm 2 f (allowable stress) = 142 N / mm2
36
HYDROGEN PEROXIDE
C.A. (corrosion allowance) = 0 mm
J (joint efficiency) = 0.85
So, ts = 0.053650 x 11,000 2 x142 x 0.85 = 2.44 mm
≈5 mm Minimum shell thickness is 5 mm. So, ts = 5 mm.
8.2.3 Calculation for No. of plates:
πd
No. of horizontal plates = nH =
L + 2x10
-3
π x 11
=
6 + 2x10-3 = 5.75
≈6 No. of vertical plates = nv = H + 2x10 -3 W + 2x10 -3 = 4 + 2x10-3 1.5 + 2x10 -3 = 3.103
≈5 plates Total no. of plates = n s = nH x nv =6x5 = 30 plates 8.2.4 Bottom design
Base dia. D b = Ds + 2 ts + 2 x welding thickness + (2 x 0.00254) = 11 + (2 x0.005) +(2 x0.002) + (0.050) 37
HYDROGEN PEROXIDE
= 11.01908 m No. of Base plates = N =
(π / 4) D b2 LxW
= (π / 4) x
(11.01908)2
6 x 1.5 = 10.5905 = 12.0 plates
8.2.5 Conical roof design
Assuming that self-supporting type conical roof can be used. Thickness of salt supporting roof: Take tr = 20 mm Pr = dead load + live load
= 1250 + (tr x ρ moc x g/gc) = 1250 + (0.020 x 7750 x 10) = 2800 N / mm
2
= 2.8 x 10 -3
Sin θ =
Pr 0.204 x E
D tr
Sin θ = [ 0.00125+(20 x 7750 x 10 -9 x 10)] 1/2 x 11019/20 0.204 x 1.9 x 10 5
Sin θ= 0.147
Tan θ= 0.1532 <0.2 Assume tr= 14 mm Sin θ= 0.194
Tan θ= 0.1967< 0.2 38
HYDROGEN PEROXIDE
So, Design is Safe for tr= 14 mm.
A1= P* D2 * Cot
θ
8*f =[0.00125+(14*7750*10-9*10)]*(11*103)2*{1/0.1967} 8 *142
A1= 587.52 mm 2
A2= Ac+As+Ar Ac = 65*65 = 4225 mm 2
As = 1.5 t r *(R* tr )1/2 R=D/2=11019/2=5509.5 = 1.5 * 5*(5509.5*5)
1/2
=1244.80 mm 2 Ar = 0.75* t r * (r * t r )1/2 r= D/2 Sin θ = 5509.5 0.194 =28399.48
Ar = 0.75* 5*(28399.5 * 5) 1/2 = 1413.09 mm 2
A2 = 4225 + 1244.80 + 1413.09 = 6882.89 mm 2
A 2 > A1 So, Design is safe.
39
HYDROGEN PEROXIDE
CHAPTER 9: PROCESS CONTROL
Effective process control can be accomplished with responsive control loops for flow, pressure, temperature, and level. Plants built in recent years and retrofits in older plants have applied instruments for detecting liquid-phase interfaces as well as for composition analysis at various points. The most recently built plants utilize state-of art electronic instrumentation. The characteristics of the extractor require particularly stable operation with respect to flow rate and composition changes.
The largest proportion of heat exchanger in the process is for cooling since both hydrogenation and oxidation are exothermic. At steady state, small heat inputs are used to establish the desired temperatures in working solution regeneration, water control, and solvent adsorption on the oxidizer exit gas if this auxiliary is used.
Periodic heat inputs are needed to desorb adsorbent beds.
Provision is necessary to keep the working solution inventory above its precipitation temperature when heats of reaction are not presen t during shutdowns.
9.1 Pressure Measurement
Pressure is defined as the force exerted over a unit area. Force may be exerted by liquid, gases and solids. Mathematically, pressure is expressed as:
P = F/A
where, p is pressure, f is force, A is area. Pressure is normally expressed in pounds per square inch (psi).
40
HYDROGEN PEROXIDE
9.1.1 Pressure Gauge
The bourdon tube is most frequently used in the pressure gauge. A bourdon tube consist of a long think walled cylinder of non circular cross section sealed at the end, made from materials such as phosphor bronze, steel & beryllium copper, and attached by a light line work to the mechanism which operates the pointer. The other and of tube is fixed and is open for the application of the pressure which is to be measured.
The tube is soldered or wended to a socket at the based, through which pressure connection is made. Bourdon tube is available in many shapes like, c type, spiral, & helical.
Advantages:9.1.1 Pressure Gauge
1. Cost is low 2. Construction is simple 3. Life is long 4. Efficiency is high 5. Tubes are in different range
Disadvantages:
1. Spring gradient is low (50psig) 2. Shock and vibration effect.
9.2 Temperature Measurement
Temperature has been defined in a variety of ways. One example defines temperature as the measure of heat associated with the movement of the molecules of a substance. This definition is based on the fact that the molecules of all matter are in continuous motion that is sensed as heat.
41
HYDROGEN PEROXIDE
Another definition is based on the concept of thermodynamics. Thermal energy always flows from a warmer body to a cooler body. In this case, temperature is defined as an intrinsic property of matter that quantifies the ability of the one body to transfer thermal energy to another body. If two bodies are in thermal equilibrium and no energy is exchanged, the bodies are at the same temperature.
In simplest terms, the temperature is the measurement of the hotness or coldness of the body.
Temperature Measuring Devices
(1) Thermocouple
(2) RTD
9.3 Flow Measurement
Flow is one of the most difficult process variables to measure accurately. One of the simplest methods for determining the flow rate is the fluid per unit time method, which
assumes a basic premise of the fluid mechanics that mass is a conserved quantity. The mass entering a system is equal to the mass leaving the system and both are measured over the same time interval.
This method for accurate flow measurement takes into consideration two basic properties of fluid, which are density densit y and viscosity and their effect ef fect on the accuracy of flow measurement.
42
HYDROGEN PEROXIDE
Density:
Density is a measurement of the proximity of the molecules that make up a substance. In the simplest terms, density is mass per unit volume. This can be expressed as:
ρ = m/V where,
ρ is density, m mass and V is volume. It is density that causes the same volume of different substance to differ in weight. It is typically expressed in pounds/cubic foot.
Viscosity:
It is property of the measure how freely the fluid flows. The unit of the viscosity is centipoises.
Specific gravity:
It is the ratio of the density of the fluids at a specific temperature to the density of the water or air at the same temperature. The specific gravity is a dimensionless quantity.
Reynolds number:
The Reynolds number is the ratio of the internal to viscous forces to flow condition.
R = internal forces/viscous forces = ρ VD / µ
Differential Pressure Meter
The basic equation from the Bernoulli‟s theorem is, Q = CA√2gh
43
HYDROGEN PEROXIDE
Where, Q is flow, C is orifice coefficient, A cross sectional area of the restriction,
g is gravitational constant h is differential pressure.
Orifice Plates
Orifice plates are the simplest and cheapest form of primary flow measuring elements and are used more frequently then all other types. An orifice plate is inserted in the pipeline perpendicular the flow and differential pressure across a cross it is measured. There are four types of orifice plates, which are concentric, eccentric, segmental, quadrant edge.
9.4 Level Measurement
Level is measured at the position of the interface between phases, where the phases are liquid/gas, solid/gas, or immiscible liquid/liquid. Level is simply a measure of height defining the position of the interface that is the surface where the two phases meet with respect to a reference point. This measurement is often converted to a volumetric or gravimetric quantity. So level may be measured directly by defining the position of the interface or indirectly by b y measuring measuri ng another quantity, such as volume and interfacing the level measurement by converting the quantity to a level measurement.
Level is a vertical measurement taken from the surface or interface to a fixed point. Normally the reference point is the bottom of the vessel holding the substance. As with most process variables, level can be measured by both direct and indirect methods.
44
HYDROGEN PEROXIDE
Level gauge
Displacer level detector
Ultrasonic level detector
Differential pressure level detector
9.5 pH METER
Method have been developed which minimizes the problems encountered when measuring Ph in pure waters. The method uses a quality glass pH electrode and
special set of a “pure water pH additive” & a special solution of diluted buffers containing the same background of “pure water pH additive”. Adding the pure water pH additive to the samples increases the ionic strength thus reducing the noise and improving time. The shift in pH caused by the addition of the
“pure water pH additive” is minimal, between 0.005 & 0.01 pH units, since the same amount of pure water pH additive is added to the buffers and samples the net effect on the pH is negligible.
45
HYDROGEN PEROXIDE
CHAPTER 10: MATERIAL SAFETY DATA SHEET
Hydrogen Peroxide
1. Product And Company Identification
Product Name: Hydrogen Peroxide (20 to 40%)
Alternate Product Name(S): Durox® Reg. & LR 35%, Oxypure® 35%, Standard
27.5 & 35%, Super D® 25 & 35, Technical 35%, HTP 35%, OHP 35%, Chlorate Grade, 20%, Semiconductor Reg, Seg, RGS, RGS 2, RGS 3, 31%
General Use:
Durox® 35% Reg. & LR - meets the Food Chemical Codex requirements for aseptic packaging and other food food related applications. Oxypure® 35% - certified by NSF to meet NSF/ANSI Standard 60 requirements for drinking water treatment. Standard 27.5 and 35% - most suitable grade for industrial bleaching, processing, pollution abatement and general oxidation oxidation reactions. Semiconductor Reg, Seg, RGS, RGS 2, RGS 3, 31% - conform to ACS and Semi Specs. for wafer etching and cleaning, and applications requiring low residues. Super D® 25 and 35% - meets US Pharmacopoeia specifications for 3% topical solutions when diluted with proper quality water. While manufactured to the USP standards for purity and to FMC's demanding ISO 9002 quality standards, FMC does not claim that it's Hydrogen Peroxide is manufactured in accordance with all pharmaceutical cGMP conditions. Technical 35% - essentially free of inorganic metals suitable for chemical synthesis. HTP 35% - specially formulated for aerospace equipment conditioning. OHP 35% - specially formulated for OHP process, advanced oxidation, and activated peroxide applications Chlorate Grade 20% - specially formulated for use in chlorate manufacture or processing. 46
HYDROGEN PEROXIDE
Hydrogen Peroxide (20 to 40%) (7722-84-1-3) Date: 06/03/2008
Manufacturer
FMC CORPORATION FMC Peroxygens 1735 Market Street Philadelphia, PA 19103 (215) 299-6000 (General Information)
[email protected] (Email - General Information) FMC of Canada Ltd. FMC Peroxygens PG Pulp Mill Road Prince George, BC V2N2S6 (250) 561-4200 (General Information)
Emergency Telephone Numbers
(281) 474-8750 (Plant: Pasadena, TX, US - Call Collect) (250) 561-4221 (Plant: Prince George, BC, Canada - Call Collect) (303) 595-9048 (Medical - U.S. - Call Collect) For leak, fire, spill, or accident emergencies, call: (800) 424-9300 (CHEMTREC - U.S.A.) (613) 996-6666 (CANUTEC - Canada)
2. Hazards Identification Identification
Emergency Overview
• Clear, colorless, odorless liquid • Oxidizer. • Contact with combustibles may cause fire. • Decomposes yielding oxygen that supports combustion of organic matters and can cause overpressure if confined. 47
HYDROGEN PEROXIDE
• Corrosive to eyes, nose, throat, lungs and gastrointestinal tract. Potential Health Effects: Corrosive to eyes, nose, throat and lungs. May cause
irreversible tissue damage to the eyes including blindness. May cause skin irritation.
3. Composition / Information On Ingredients
Hydrogen Peroxide 7722-84-1 20 - 40 231-765-0 O, C, Xn; R5- R8-R35- R20/22 Water 7732-18-5 60 - 80 231-791-2 Not classified Hydrogen Peroxide (20 to 40%) (7722-84-1-3) Date: 06/03/2008
4. First Aid Measures
Eyes: Immediately flush with water for at least 15 minutes, lifting the upper and
lower eyelids intermittently. See a medical doctor or ophthalmologist immediately. Skin: Wash with plenty of soap and water. Get medical attention if irritation occurs
and persists. Ingestion: Rinse mouth with water. Dilute by giving 1 or 2 glasses of water. Do not
induce vomiting. Never give anything by mouth to an unconscious person. See a medical doctor immediately. Inhalation: Remove to fresh air. If breathing difficulty or discomfort occurs and
persists, contact a medical doctor. Notes to Medical Doctor: Hydrogen peroxide at these concentrations is a strong
oxidant. Direct contact with the eye is likely to cause corneal damage especially if not washed immediately. Careful ophthalmologic evaluation is recommended and the possibility of local corticosteroid therapy should be considered. Because of the likelihood of corrosive effects on the gastrointestinal tract after ingestion, and the unlikelihood of systemic effects, attempts at evacuating the stomach via emesis induction or gastric lavage should be avoided.
5. Fire Fighting Measures
Extinguishing Media: Flood with water. Fire / Explosion Hazards: Product is non-combustible. On decomposition releases
48
HYDROGEN PEROXIDE
oxygen which may intensify fire. Fire Fighting Procedures: Any tank or container surrounded by fire should be
flooded with water for cooling. Wear full protective clothing and self-contained breathing apparatus. Flammable Limits: Non-combustible Sensitivity To Impact: No data available Sensitivity To Static Discharge: No data available
6. Accidental Release Measures
Release Notes: Dilute with a large volume of water and hold in a pond or diked area
untilhydrogen peroxide decomposes. Hydrogen peroxide may be decomposed by adding sodium metabisulfite or sodium sulfite after diluting to about 5%. Dispose according to methods outlined for waste disposal. Hydrogen Peroxide (20 to 40%) (7722-84-1-3) Date: 06/03/2008 Combustible materials exposed to hydrogen peroxide should be immediately submerged in or rinsed with large amounts of water to ensure that all hydrogen peroxide is removed. Residual hydrogen peroxide that is allowed to dry (upon evaporation hydrogen peroxide can concentrate) on organic materials such as paper, fabrics, cotton, leather, wood or other combustibles can cause the material to ignite and result in a fire.
7. Handling And Storage
Handling: Wear chemical splash-type monogoggles and full-face shield, impervious
clothing, such as rubber, PVC, etc., and rubber or neoprene gloves and shoes. Avoid cotton, wool and leather. Avoid excessive heat and contamination. Contamination may cause decomposition and generation of oxygen gas which could result in high pressures and possible container rupture. Hydrogen peroxide should be stored st ored only in vented containers and transferred only in a prescribed manner (see FMC Technical Bulletins).
49
HYDROGEN PEROXIDE
Never return unused hydrogen peroxide to t o original container, empty drums should be triple rinsed with water before discarding. Utensils used for handling hydrogen peroxide should only be made of glass, stainless steel, aluminum or plastic.
Storage: Store drums in cool areas out of direct sunlight and away from
combustibles. For bulk storage refer to FMC Technical Bulletins.
Comments: VENTILATION: Provide mechanical general and/or local exhaust
ventilation to prevent release of vapor or mist into the work environment.
8. Exposure Controls / Personal Protection Protection
Exposure Limits
Hydrogen Peroxide 1 ppm (TWA) 1 ppm (PEL) 1.4 mg/m3 (PEL) Engineering Controls: Ventilation should be provided to minimize the release of
hydrogen peroxide vapors and mists into the work environment. Spills should be minimized or confined immediately to prevent release into the work area. Remove contaminated clothing immediately and wash before reuse.
Personal Protective Equipment
Eyes And Face: Use chemical splash-type monogoggles and a full-face shield made
of polycarbonate, acetate, polycarbonate/acetate, PETG or thermoplastic.
Respiratory: If concentrations in excess of 10 ppm are expected, use NIOSH/DHHS
approved self-contained breathing apparatus (SCBA), or other approved atmosphericsupplied respirator (ASR) equipment (e.g., a full-face airline respirator (ALR)). DO NOT use any an y form of air-purifying respirator (APR) or filtering facepiece facepiec e (AKA dust mask), especially those containing oxidizable sorbants such as activated carbon. Hydrogen Peroxide (20 to 40%) (7722-84-1-3) Date: 06/03/2008
Protective Clothing: For body protection wear impervious clothing such as an
approved splash protective suit made of SBR Rubber, PVC (PVC Outershell w/Polyester Substrate), Gore-Tex (Polyester trilaminate w/Gore-Tex), or a specialized 50
HYDROGEN PEROXIDE
HAZMAT Splash or Protective Suite (Level A, B, or C). For foot protection, wear approved boots made of NBR, PVC, Polyurethane, or neoprene. Overboots made of Latex or PVC, as well as firefighter boots or specialized HAZMAT boots are also permitted. DO NOT wear any form of boot or overboots made of nylon or nylon blends. DO NOT use cotton, wool or leather, as these materials react RAPIDLY with higher concentrations of hydrogen peroxide. Completely submerge hydrogen peroxide contaminated clothing or other materials in water prior to drying. Residual hydrogen peroxide, if i f allowed to dry on materials such as paper, fabrics, f abrics, cotton, leather, wood or other combustibles can cause the material to ignite and result in a fire.
Gloves: For hand protection, wear approved gloves made of nitrile, PVC, or
neoprene. DO NOT use cotton, wool or leather for these materials react RAPIDLY with higher concentrations of hydrogen peroxide. Thoroughly rinse the outside of gloves with water prior to removal. Inspect regularly for leaks.
9. Physical And Chemical Properties
Odor: Odorless Appearance: Clear, colorless liquid Auto-ignition Temperature: Non-combustible Boiling Point: 103ºC/218ºF (20%); 107ºC/225ºF (31%); 108ºC/226ºF(35%) Coefficient Of Oil / Water: Water: Not available Density / Weight Per Volume: Not available Evaporation Rate: > 1 (Butyl Acetate = 1) Flash Point: Non-combustible Freezing Point: -15ºC/6ºF (20%); -26ºC/-15ºF (31%); -33ºC/-27ºF (35%) Odor Threshold: Not available Oxidizing Properties: Properties: Strong oxidizer Percent Volatile: 100 pH: <= 3.7, 5.0 - 6.0 @ 25 °C (1% solution) Solubility In Water: 100 % Specific Gravity: 1.07 @ 20ºC/4ºC (20%); 1.11 @ 20ºC/4ºC (31%); 1.13 @20ºC/4ºC
(35%) 51
HYDROGEN PEROXIDE
Vapor Density: (Air = 1): Not available Vapor Pressure: 28 mmHg @ 30ºC (20%); 24 mmHg @ 30ºC (31%); 23 mmHg @
30ºC (35%) Hydrogen Peroxide (20 to 40%) (7722-84-1-3) Date: 06/03/2008
10. Stability And Reactivity
Conditions To Avoid: Excessive heat or contamination could cause product to
become unstable. Stability: Stable (heat and contamination could cause decomposition) Polymerization: Will not occur Incompatible Incompatible Materials: Reducing agents, wood, paper and other combustibles, iron
and other heavy metals, copper alloys and caustic. Hazardous Decomposition Products: Oxygen which supports combustion. Comments: Materials to Avoid: Dirt, organics, cyanides and combustibles such as
wood, paper, oils, etc.
11. Toxicological Information Information
Eye Effects: 35% hydrogen peroxide: Extremely irritating/corrosive (rabbit) [FMC
Study Number: I83-748] Skin Effects: 35% hydrogen peroxide: Mildly irritating after 4-hour exposure (rabbit)
[FMC Study Number: I83-747] Dermal Ld50: 35% Hydrogen Peroxide: > 2,000 Mg/Kg (Rabbit) [Fmc Study
Number: I83-746] Oral Ld50: 35% hydrogen peroxide: 1,193 mg/kg (rat) [FMC Study Number: I83-
745] Inhalation LC50: 50% hydrogen peroxide: > 0.17 mg/l (rat) [FMC Study Number:
I89-1080] Target Organs: Eyes, nose, throat and lungs Acute Effects From Over exposure: Extremely irritating/corrosive to eyes and
gastrointestinal tract. May cause irreversible tissue damage to the eyes including
52
HYDROGEN PEROXIDE
blindness. Inhalation of o f mist or vapors may be severely irritating to nose, throat and lungs. May cause skin irritation. Chronic Effects From Over exposure: The International Agency for Research on
Cancer (IARC) has concluded that there is inadequate evidence for carcinogenicity of hydrogen peroxide in humans, but limited evidence in experimental animals (Group 3 - not classifiable as to its carcinogenicity to humans). The American Conference of Governmental Industrial Hygienists (ACGIH) has concluded that hydrogen peroxide
is a „Confirmed Animal Carcinogen with Unknown Relevance to Humans‟ (A3). Hydrogen Peroxide (20 to 40%) (7722-84-1-3) Date: 06/03/2008
Carcinogenicity: Chemical Name IARC NTP OSHA Other
Hydrogen Peroxide Not listed Not listed Not listed (ACGIH) Listed (A3, Animal Carcinogen)
12. Ecological Information
mg/ L Ecotoxicological Ecotoxicological Information: Channel catfish 96-hour LC50 = 37.4 mg/L Fathead minnow 96-hour LC50 = 16.4 mg/L Daphnia magna 24-hour EC50 = 7.7 mg/L Daphnia pulex 48-hour LC50 = 2.4 mg/L Freshwater snail 96-hour LC50 = 17.7 mg/L For more information refer to ECETOC "Joint Assessment of Commodity Chemicals No. 22, Hydrogen Hydrogen Peroxide." ISSN-0773-6339, ISSN-0773-6339, January 1993
Chemical Fate Information: Hydrogen peroxide in the aquatic environment is
subject to various reduction or oxidation processes and decomposes into water and oxygen. Hydrogen peroxide half-life in freshwater ranged from 8 hours to 20 days, in air from 10-20 hrs. and in soils from minutes to hours depending upon microbiological activity and metal contaminants.
53
HYDROGEN PEROXIDE
13. Disposal Considerations Considerations
Disposal Method: An acceptable method of disposal is to dilute with a large amount
of water and allow the hydrogen peroxide to decompose followed by discharge into a suitable treatment system in accordance with all regulatory agencies. The appropriate regulatory agencies should be contacted prior to disposal.
54
HYDROGEN PEROXIDE
CHAPTER 11: SAFETY AND HANDLING
11.1 Environmental Applications Stand-Alone Applications
Odor control - Oxidizes hydrogen sulfide, mercaptans, amines and aldehydes. H2O2 may be applied directly to aqueous wastes containing these odorants, or to wet scrubbers used to remove them from airstreams. If the odors are the result of biological activity, activit y, H2O2 may instead be added as a preventative to eliminate the anoxic conditions which favor the generation of odors. Corrosion control - destroys residual chlorine and reduced sulfur compounds thiosulfates, sulfites, and sulfides) which form corrosive acids when condensed onto processing equipment and oxidized by air. BOD/COD removal - Oxidizes both organic and inorganic pollutants which contribute to BOD and COD -- catalytic, H2O2 may be needed to oxidize the more resistant substances. H2O2 may also affect BOD/COD removal by enhancing the performance of other processes. Inorganic oxidation - Oxidizes cyanides, NOx/SOx, nitrites, hydrazine, carbonyl sulfide, and other reduced sulfur compounds mentioned above (odor/corrosion control). Organic oxidation - Hydrolyzes formaldehyde, carbon disulfide, carbohydrates, organophosphorus and nitrogen compounds, and various water-soluble polymers; and (with catalysis) destroys phenols, BTEX pesticides, solvents, plasticizers, chelants, and virtually any other organic requiring treatment. Metals oxidation - Oxidizes ferrous iron, manganese, arsenic, and selenium to improve their adsorption, filtration, or precipitation from process waters and wastewaters.
55
HYDROGEN PEROXIDE
Toxicity reduction/Biodegradability improvement - With catalysis, chemically digests complex organics into smaller, less toxic and more biodegradable fragments. Hydrogen peroxide is well-established as an environmentally-friendly deodorizing
and bleaching agent. Its uses include organic and inorganic chemical processing, textile and pulp bleaching, metal treating, cosmetic applications, catalysis of polymerization reactions, municipal odor control, industrial waste treatment (detoxification), and control of bulking in wastewaters. These uses are continually expanding, making it a necessity not only to understand the mode of hydrogen peroxide application but the safe handling of the chemical as well. 11.2 Hazards
Hydrogen peroxide, either in pure or diluted form, can pose several risks: Above roughly 70% concentrations, hydrogen peroxide can give off vapor that can detonate above 70 °C (158 °F) at normal atmospheric pressure. This can then cause a boiling liquid expanding vapor explosion of the remaining liquid. Distillation of hydrogen peroxide at normal pressures is thus highly dangerous. Hydrogen peroxide vapors can form sensitive contact explosives with hydrocarbons such as greases. Hazardous reactions ranging from ignition to explosion have been reported with alcohols, with alcohols, ketones, ketones, carboxylic carboxylic acids (particularly acetic (particularly acetic acid), acid), amines and phosphorus. The
saying is 'peroxides kill chemists‟. Hydrogen peroxide, if spilled on
clothing (or other flammable materials), will preferentially evaporate water until the concentration reaches sufficient strength, then clothing will spontaneously ignite. Leather generally contains metal ions from the tanning process and will often catch fire almost immediately. Concentrated hydrogen peroxide (>50%) is corrosive, and even domestic-strength solutions can cause irritation to the eyes, mucous membranes and skin. Swallowing hydrogen peroxide solutions is particularly dangerous, as decomposition in the stomach releases large quantities of gas (10 times the volume of a 3% solution) leading to internal bleeding. Inhaling over 10% can cause severe pulmonary irritation. Low concentrations of hydrogen peroxide, on the order of 3% or less, will chemically 56
HYDROGEN PEROXIDE
stain any clothing it comes into contact with a pinkish hue. Caution should be exercised when using common products that may contain hydrogen peroxide, such as facial cleaner or contact lens solution, which easily splatter upon other surfaces. Hydrogen peroxide is naturally produced as a byproduct of oxygen metabolism, and virtually all organisms possess enzymes known as peroxides, peroxides, which apparently harmlessly catalytically decomposes low concentrations of hydrogen peroxide to water and oxygen. Hydrogen peroxide was also part of the ingredients in the July 21, 2005 London Underground bombs, which failed to explode. 11.3 Properties of Hydrogen Peroxide
A basic understanding of the properties of hydrogen peroxide is essential to the safe handling of this chemical. Hydrogen peroxide is clear, colorless, waterlike in appearance, and has a characteristic pungent odor. Nonflammable, it is miscible with water in all proportions and is sold as a water solution. The amount of hydrogen peroxide in commercial solutions is expressed as a percentage of the solution's weight. Thus, a 35% solution contains 35% hydrogen peroxide and 65% water by weight. Most municipal and industrial applications call for 35% or 50% concentrations.
11.4 Delivery and Storage
The methods available for delivery to bulk storage installations accommodate shipments of 70% hydrogen peroxide for dilution to the 35% or 50% storage concentrations. Solutions containing more than 8% hydrogen peroxide are classified by the U.S. Department of Transportation Transportation (DOT) as an oxidizer. Under normal conditions hydrogen peroxide is extremely sta ble when properly stored. Rate loss in large containers such as tanks is less than 1% per year at normal ambient temperatures; in small containers, such as drums, rate loss is less than 2% per year.
57
HYDROGEN PEROXIDE
The larger the ratio of the storage container surface areas to the volume of hydrogen peroxide, the greater the rate loss. Decomposition of hydrogen peroxide liberates oxygen and heat. In dilute solutions the heat evolved is readily absorbed by the water present. In more concentrated solutions, the heat raises the temperature of the solution and accelerates the decomposition rate. Special stabilizers are added during the manufacture of all grades of hydrogen peroxide to inhibit the catalytic decomposition effect of metals and other impurities that may accidentally contaminate the chemical during shipment, storage, and handling. However, since no additive will prevent decomposition if excessive contamination occurs, the best practice is to prevent contamination through proper handling. All handling procedures must, therefore, be directed towards maintaining the same degree of purity and freedom from contamination as is maintained during the manufacturing process:
Storage of hydrogen peroxide should be restricted to its original shipping container or to properly designed containers made of compatible materials which have been thoroughly passivated.
Hydrogen peroxide that has been removed from the original shipping container should not be returned to it.
All containers must be properly vented, and preferably stored away from sources of direct heat and combustible materials.
Adequate ventilation and ample water supply for thorough flushing of accidental spillage on personnel and property should be provided.
Hydrogen peroxide itself will not burn, but its decomposition liberates oxygen which supports combustion. Fires involving hydrogen peroxide are best controlled by using large quantities of water.
58
HYDROGEN PEROXIDE
Hydrogen peroxide is not considered an explosive. However, when it is mixed with organic
substances
at
significant
concentrations,
hazardous
impact-sensitive
compounds may result. Small amounts of other materials that contain catalysts (silver, lead, copper, chromium, mercury, and iron oxide rust) can cause rapid decomposition and an explosive pressure rupture of the containing vessel if it is not properly vented. In addition to accelerated decomposition through contamination, the decomposition rate of hydrogen peroxide is increased with alkalinity, contact with certain materials of construction, and increasing temperatures. The rate of decomposition increases approximately 2.2 times for each 10 degrees C rise in temperature in the range from 20 degrees C to 100 degrees C, or 1.5 times for each 10 degrees F rise from 68 degrees F to 212 degrees F. Decreasing temperatures have little effect on hydrogen peroxide until they drop substantially below 0 degrees C. Crystals do not begin to appear in 35% and 50% solutions until -33C (-27.4F) and -52.2C (-62F), respecti vely.
11.5 Eye Protection
Hydrogen peroxide and its decomposition products are not systematic poisons but contact with hydrogen peroxide can be irritating. Concentrated vapors cause discomfort in the mucous membranes and the eyes. Contact of the eyes with hydrogen peroxide is particularly dangerous because corneal burns can occur very rapidly. Therefore, safety glasses or, preferably, goggles should always be worn when handling concentrated hydrogen peroxide. If, however, any hydrogen peroxide does get in the eyes, flush eyes thoroughly with water and consult a physician promptly.
11.6 Protective Clothing
In addition to eye protection, rubber gloves and suitable protective clothing such as aprons or coveralls made of polyester acrylic fiber, polyvinyl chloride, polyethylene, or neoprene should be worn when handling concentrated hydrogen peroxide. Protective clothing, which lacks fire resistance, must be washed thoroughly with
59
HYDROGEN PEROXIDE
water should it come in contact with hydrogen peroxide. If allowed to dry in the fabric, the chemical may cause fire, particularly if the clothing is soiled. Contact with moderate concentrations of hydrogen peroxide will cause whitening of the skin and stinging sensations. The whitening is due to the formation of gas bubbles in the epidermal layer of the skin. The stinging, in most cases, subsides quickly after thorough washing, and the skin gradually returns to normal without any damage. Highly concentrated hydrogen peroxide can cause blistering if left on skin s urfaces for any length of time.
11.7 Accidental Swallowing
Hydrogen peroxide, a mild disinfectant, is useful in counteracting various microorganisms. Because of their antiseptic action, dilute hydrogen peroxide solutions (3% or less) are frequently used to treat open wounds and can be used as a gargle or mouthwash. However, contact or concentrated solutions (over 3%) with the members of the mouth is to be avoided. Under no circumstances should hydrogen peroxide be taken internally. If hydrogen peroxide is swallowed, drink water immediately to dilute, and contact a physician but do not attempt to cause vomiting. In using hydrogen peroxide, safety should be first in the minds of everyone, and as with any other chemical, initial steps should be taken to familiarize all personnel with its safe and proper handling. Acceptance of hydrogen peroxide in a wide variety of industrial applications is a reflection of its simplicity in use. Maximum safety in handling hydrogen peroxide is assured through the use of proper materials of construction, recognition of the need for venting in storage, and overall avoidance of contamination. The oxygen and water by-products of decomposition are innocuous, but splashing, inhaling vapor, and ingesting hydrogen peroxide must be avoided. If by unusual circumstances an accident should take place, flushing with large quantities of plain water is the simple corrective action needed. By adhering to straight-forward common sense procedures, every aspect of your operation will be aimed toward safety and a clean environment.
60
HYDROGEN PEROXIDE
CHAPTER 12: PLANT LAYOUT
Following Factor should be considered in planning layout: (1) New (1) New site development or addition to a previously previously development site. (2) Future expansion. (3) Economic distribution of service-water, process-steam, power and gas. (4) Weather consideration, are they amenable to outdoor construction. (5) Safety consideration, possible hazards of fire, explosion and flumes. (6) Building code requirement. (7) Sensible use of floor and elevation space.
12.1 Storage
Regulations vary, but low concentrations, such as 2.5% are widely available and legal to buy for medical use. Small quantities of many different concentrations and grades can be legally stored and used with few regulations. Hydrogen peroxide should be stored in a container made from a material that it doesn't react with and doesn't catalyze its decomposition. Numerous materials and processes are available, some stainless steels, many plastics, glasses and some aluminum alloys are compatible. Peroxide is a strong oxidant and should be stored away from fuel sources and sources of catalytic contamination. Apart from obvious fire risks, peroxide vapor can react with hydrocarbons and alcohols to form contact explosives. Because oxygen is formed during the natural decomposition of the peroxide, the resulting increase in pressure can cause a container (e.g. made of glass) to shatter. Peroxide should be kept cool, as peroxide vapor can detonate above 70 °C. Deaths have occurred from storage in inadequately labeled containers due to its apparent similarity to water.
61
CONCLUSION
HYDROGEN PEROXIDE
PRODUCT PACKAGE PARKING
AND
AREA
STORAGE
EFFLUENT TREATMENT PLANT
PROCESSING AREA
PLANTATION AREA FUTURE EXPANSION
RAW MATERIAL STORAGE AREA
SECURITY OFFICE
PLANTATION
FIRE AND
UTILITY AREA
AREA
SAFETY DEPARTMENT
POWER TRANMISSION
ADMINISTRATION
R&D
DEPARTMENT
LABORATORY CANTEEN
SHOP
86
MAINTAINENCE
CONCLUSION
HYDROGEN PEROXIDE
12.2 Factor Affecting the Final Selection
Raw material
Ample supply of material should be available regularly as per requirements. This reduces the transportation & hence reduce produce the transportation & hence reduce production cost.
Market
Plant should be located in center of market or nearer to the market which helps in studying market property, reduces delays in supply & also reduces transportation cost.
Power & fuel supply
Electricity & fuel should be available of at the site regularly & cheaply otherwise process ability may cease.
Water supply
Plant is located where sufficient water is available.
Climates
Weather condition considerably affects the plant location temperature & humidity shall be favorable. 12.3 Specific Factor
Transportation
Railway & roads are common means of transportation. So they must be available for raw materials for product transportation.
Water & Waste Disposal
Plant site should have adequate & proper facility for correct wat er & waste disposal.
87
CONCLUSION
HYDROGEN PEROXIDE
Labor
Availability of skilled labor with constant supply & reasonable pay rate should be considered while selecting the site.
Taxes & legal phases
State & local tax rates & property, income, unemployment insurance zoning ordinance, building codes etc. have major influence.
Site characteristic characteristic
The site should facilities, soil; structure should be good for building & easily available for future expansion of plant.
Miscellaneous
Various more factors like community around plant site, fire highly facility, advance library & training center, housing cost, etc. also affect the location. Thus, considering all above major factors & nature of our plant we can select the best suitable place for our plant near vadodara. 12.4 Utilities
The Synthesis Loop and peroxide processing stages are dependent on a number of ancillary processes.
Hydrogen Plant
This plant processes natural gas through a steam reforming stage and subsequent high temperature shift catal catalytic ytic stage to produce high purity hydrogen gas. The gas is finally purified purified in a pressure pressure swing absorber absorber before being used by the hydrogenat hydrogenator or Details of this process can be found in the manufacture of methanol.
Demineralised Water
High purity water is used to feed the extractor, concentrator as well as the package package boiler. boiler. Convent Conventiona ionall degassing degassing followed followed by cation cation and anion exchange exchange beds is used to purify town water for use in the peroxide process. 88
CONCLUSION
HYDROGEN PEROXIDE
Package Boiler
A small boiler generates steam for use in concentrating crude peroxide from 25-35% to 35-70%.
Waste Gas System
The oxidiser can produce an exit gas containing trace levels of solvents. The solvententrained gas is fed to a bed of activated carbon where the solvents are absorbed onto the carbon. The activated carbon is purged with nitrogen gas and the solvent is stripped off and recovered for reuse in the synthesis loop.
Calciner Systems
A calciner is used used to regenerate regenerate spent catalyst catalyst on a periodic periodic basis. The catalyst is removed from the regenerators, washed and then roasted to remove any other organics that might be present. These organics, if not removed, will block the catalytic sites on the catalyst and lower its activity.
Fire System
The hydrogen peroxide manufacturing process uses natural gas, hydrogen and organic solvents, all of which are highly highly flammable. The site is equipped with a delug system with foam injection. In addition, the local fire brigade has been provided with a foam tender.
Working Solution Regeneration
Hydrogenation generates not only peroxide-producing anthrahydroquinones but also some by-products. converted
These by-products include anthraquinone species that can be
back to useful quinones by regeneration.
During regeneration process, aside-stream of working solution is fed through a bed of dehydrogenation catalyst. The regeneration converts epoxidised anthraquinones and tetrahydroanthraquinones to their corresponding anthraquinones.
89
CONCLUSION
HYDROGEN PEROXIDE
CHAPTER 13: COST ESTIMATION AND PROFITABILITY
[1] Direct Cost = (A+B+C+D+E) Now,
A= Equipment B=Installation C= Instrumentation D=Piping E=Electrical.
Now, (1) Equipment Equipment Costs Sr No. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)
Name of Unit
Quantity
Hydrogenation Unit Oxidation Unit Extraction Unit Catalyst particle barrier Degassing unit Air supply unit Water storage tank Working solution st. tank Hydrogen peroxide st. tank Hydrogen supply unit Pumps
1 1 1 1 1 1 1 1 1 1 As required TOTAL (X)
Cost 500000 800000 700000 300000 200000 600000 550000 550000 600000 600000 200000 Rs. 5600000/-
(2) Installation cost (including installation and painting) = 30% of X = Rs. 1680000/-
(3) Instrumentation and control installed
= 20% of X = Rs. 1120000/-
(4) Piping Installed
= 25% of X = Rs. 1400000/-
(5) Building costs
= 20% of X = Rs. 1120000/-
90
CONCLUSION
HYDROGEN PEROXIDE
(6) Service facilities and Ward improvement i mprovement = 50% of X = Rs. 2800000/(7) Land = 50% of X = Rs. 840 Total Cost = Rs. 14560000/-
[2] Indirect Cost = (A+B+C)
A) Engineers and Supervisor = 30% of X =Rs. 1680000/B) Construction & Expenses = 34% of X =Rs. 1904000/C) Contingency
= 10% of X = Rs. 560000/Total Cost = Rs. 4144000/-
[3] Fixed Capital Investment = Direct Cost + Indirect Cost = 14560000 + 4144000 = Rs. 18704000/-
[4]Working Capital = 10% OF FCI = Rs. 1870400/-
[5] Total Capital = Fixed Capital + Working Capital = 18704000 + 1870400 = Rs. 20574400
[6] Operating Suppliers = 15% Of Cost Of Maintenance And Repair = Rs. 840000/-
[7] Laboratory Charges = 15% Of X = Rs. 840000/-
(A) Fixed Charges (1) Depreciation: = 10% of fixed capital investment = 0.10 x 18704000 = Rs. 1870400/91
CONCLUSION
HYDROGEN PEROXIDE
(2) Local Taxes: = 3% of fixed capital investment = 0.03 x 18704000 = Rs. 561120/(3) Insurance: = 1% of fixed capital investment = Rs. 187040/(4) Rent : = 8% of building = 0.08 x 1120000 = Rs. 89600/Fixed Charges (1+2+3+4) = Rs. 2708160 (B) Plant Overhead Costs = 10% of total product cost=0.10y = 0.10 x 188591200 = Rs.18859120 /-
(C) General Expenses = A+B+C+D = 0.02Y + 1440208 A = Administration costs = 4%Y B = Distribution and selling cost = 11%Y C = Research and development costs = 5%Y D = financing (interest) = 7% of total capital investment = 0.07 x 20574400 = Rs. 1440208/(D) Mfg. Cost = (A+B+C) (A+ B+C) = 0.66Y + 24962560 A = Raw material cost = 40%Y B = Electricity & Utility Cost = 20%Y C = House keeping Cost = 6%
92
CONCLUSION
HYDROGEN PEROXIDE
(E) Total Product Cost = Mfg. Cost + General Expenses = (24962560 + 0.66Y) + (0.20Y + 1440208) Y = 26402768 + 0.86Y Y = Rs. 188591200/-
Sales: 10000 TPA (40 Rs./Kg) Selling Commission to asset Sales Total
= 400000000/= 20000000/= 20000000/= Rs.440000000/-
Profitability = Gross Income – Total Total Production Capacity = 440000000 – 188591200 188591200 = Rs. 251408800/Less 60% income tax = Rs. 150845280/-
Profit (Net) = 251408800 – 150845280 150845280 = Rs. 100563520/-
Payout period
= Fixed capital investment -----------------------------------------------------(Net Profit + Depreciation) =
18704000 ------------------------------------------------------(100563520 + 1870400)
= 0.1826 years = 2.5 Month
% Rate of Return (before taxes)=
=
GrossEarni ngx100 100 Totalcapit alInvestment
440000000x100 20574400
= 2138.57%
93
CONCLUSION
HYDROGEN PEROXIDE
% Rate of Return (After taxes)=
=
netprofita ftertax ftertax *100 totalCapit alInvestment
100563520x100 20574400
= 488.77%
Break Even Point
Direct product cost (Rs/ kg) = Annual Production cost (Rs) × Sale s Price (Rs/ kg) Annual sales (Rs) = 188591200×
40
.
440000000 = 17.14Rs/ kg kg/ annum (n) required for break even point = Fixed charges + General expense
.
Sales Price (Rs/ kg) - Direct product cost (Rs/ kg) =
27670720. 40- 17.14
= 1210442.69 kg/ annum Annual capacity of the plant pl ant is 10000000 kg. Break even point = kg/ annum annum (n) required for break break even point point 100 Annual production =
1210442.69
× 100
10000000 = 12.10 % of capacity. capacit y.
94
CONCLUSION
HYDROGEN PEROXIDE
CONCLUSION
In this project, I have used such as materials quinone, hydrogen, and oxygen for the manufacture of the hydrogen peroxide. These are widely used in the industries & are the most economical than the other processes. Hydrogen peroxide is a much weaker base base than water in nature. Mol wt. is 34 kg/kg mole. The use of hydrogen peroxide is in the Bleaching wood pulp, Detoxification of cyanide tailings, Bleaching of cotton fabrics, Bleaching of wool, Measuring dissolved oxygen, Destroying soluble cyanides, sulfides and phenols, Aseptic packaging of milk and fruit juice Warning:1. Physiologically, a prominent factor in process safety is to prevent hydrogen peroxide from splashing on personnel, particularly on sensitive membrane m embrane areas such as eyes. 2. Hazardous reactions ranging from ignition to explosion have been reported with alcohols, ketones, alcohols, ketones, carboxylic carboxylic acids (particularly acetic (particularly acetic acid), acid), amines and phosphorus. and phosphorus. 3. Hydrogen peroxide vapors can form sensitive contact explosives with hydrocarbons such as greases. Material of construction for process is Austenitic stainless steels and certain grades of aluminum are used almost universally for vessels, piping, valves, and pumps. Stainless steel grades 304 and 316 are used widely. Aluminum grades 5652, 1060, and
1100 are satisfactory but less used in plants built in recent years. Aluminum‟s ability to self-passivate with an oxide coating is a property which commends the metal particularly to peroxide handling. The IUPAC name of hydrogen peroxide: Dihydrogen dioxide.
95
HYDROGEN PEROXIDE
REFERENCES
1. Kirk & Othmer; Encyclopedia of Chemical Technology, Wiley Inter-Science,4 Inter-Science,4th Ed.,13,961-989 2. Ullman; Ullaman‟s Encyclopedia of industrial chemistry, chemistr y, Wiley-VCH , 6th ED, Vol.4,671-686 3. Plant Manual, Gujarat Alkali Limited (GACL), Vadodara. 4. Rao Gopal; Sitting Marshall; Dryden‟s Outlines Of chemical
Technology,
East-Wast Press, Press, 3rd Ed, 454. 5. Bhatt B. I. & Vora S. M. ,Stoichiometry, Tata McGraw-Hill , 3rd Ed.,58-112 6. Treybal, R.E; Mass Transfer operation, Tata McGraw Hill , 3rd Ed.,21-78 7. http://msds.fmc.com/msds/100000010225-MSDS_US-E.pdf 8. htp://www.sterrad.com/customer_support/user_resources/msds/h2o2_msds.pdf 9. B.J. Bhatt; S.M. Vora, Stiochiometry, Sti ochiometry, Tata McGraw Hill , New Delhi,3rd Ed.
10. M.V.Joshi; V.V.Mahajini, “Process Equipment Design”, 3 rd Ed. 11. S.B. Thakore; D.A.Shah, Illustrated Process Equipment Design, 1 st Ed.,2002 12. R.W Perry; D.W. Green, “Chemical Engineers Handbook”, Tata McGraw Hill ,7 ,7th Ed.
13. M.L. Luyben; W.L. Luyben, “Essentials of Process Control”, Tata McGraw Hill ,2 ,2nd Ed. 14. http://www.h2o2.com/intro/safety.htm
96
