Steam Generation & Distribution.pdf

MODUL ULE E 14 LEARNING OBJECTIVES In this module you will learn about:

General Objectives: L

Steam Generation and Distribution.

Specific Objectives: L

The Use of Steam in Industrial Plants and Processes,

L

How Steam is Generated and Distributed for End-Use,

L

Use of Steam Tables to Calculate Energy/Mass Balance,

L

Steam Quality,

L

Heat Recovery from Flash Steam and Blow Down,

L

Boiler Plant Equipment & Operation,

L

Boiler Plant Efficiency.

Performance Objectives: After successfully completing this module you y ou will be able to: L

L

L

L

L

Examine steam distribution systems including steam trap operation, steam leakage, condensate return, and water treatment. Evaluate the steam distribution system including boiler combustion efficiency. Prepare a boiler mass balance, including boiler blow-down, make-up and feedwater quantities.

N O I N O T I A T R U E B I N R E T G S I M D A E & T S

Evaluate feedwater treatment procedures. Make recommendations for system improvement based on your evaluations.

SADC Industri Industrial al Energ Energy Management Proj Project Implemented by AGRA Monenco Atlantic Limited for the Canadian International Development Agency

Module 14 Steam Generation & Distribution

TABLE OF CONTENTS 1.0

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1

2.0

PRINCIPLES OF STEAM GENERATION AND STEAM TABLES . . .

2

3.0

BOILER HOUSE OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6

3.1 3.2 3.3 3.4 3.5 3.6

Energy Flow and Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . Burners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Boilers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Feedwater Tr Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Boiler Plant Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Boiler Plant Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6 7 8 10 11 12

STEAM DISTRIBUTION SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . .

16

4.1 4.2 4.3

Steam Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Steam Traps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flash Steam Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

16 17 20

5.0

END-USE EQUIPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

21

6.0

ENERGY MANAGEMENT OPPORTUNITIES . . . . . . . . . . . . . . . . . .

24

6.1 6.2 6.3

Housekeeping Opportunities . . . . . . . . . . . . . . . . . . . . . . . . . Low Cost Opportunities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Retrofit Opportunities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

24 25 26

WORKED EXAMPLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

26

4.0

7.0

7.1 7.2 7.2 7.3

Relocate Combustion Air Intake (Boiler House) . . . . . . . . . . . 26 Repl Replac ace e or or Rep Repai airr Lea Leaki king ng Trap Traps s (St (Stea eam m Dis Distr trib ibut utio ion n Sys Syste tem) m) 27 Shut Down Equipment (End-Use Equipment) . . . . . . . . . . . . 28

8.0

ASSIGNMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

29

9.0

SUMMARY - Module 14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

31

MODULE 14 STEAM GENERATION & DISTRIBUTION 1.0 1.0 INTR INTROD ODUC UCTI TION ON A signi significa ficant nt perce percentag ntage e of world's world's fuel fuel supply is used to generate steam st eam for power production, production, industrial processes and commercial space heating. The reasons for this popularity are simple: <

<

< < <

Steam Steam carrie carries s a very high heat content. Relatively small pipes can carry a great amount amount of of heat. Steam at at low temperature temperature contains contain s about twenty-fiv twent y-five e times as much heat as the same weight of air or flue gases at the same temperature. Steam gives gives up its heat at constant constant temperature temperature.. It gives a complete control contr ol of the t he heating operation. When steam condenses by giving up its latent heat to the heated surface, it does so at constant temperature at corresponding pressure. Steam is generated from water which is cheap and plentiful. The heat in steam can be used again and again. Steam can generate power first and can then be used for heating.

Figure 14.1 TYPICAL STEAM SYSTEM

SADC Industrial Energy Management Project

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Module 14 - Steam Generation & Distribut ion ....

Fuel conversion systems, such as boilers, extract energy from primary sources (fuels) and convert it into secondary form of energy such as steam, hot water or hot air. The main task involved in assessing these systems is to determine their fuel conversion efficiency. The combustion of fuels comprises the major part of the steam generating process. The fundamentals and testing procedures of fuel fired systems are described in Module 13 and apply to steam and hot water boilers. Module 14 gives the background to the generation, distribution and end-use of steam and provides guidelines for assessing and improving the efficiency of these processes. Figure 14.1 shows a diagram of the overall steam system including the inputs and losses peculiar to the production, distribution and end-use of steam. Figure 14.2 presents a picture of a typical industrial application of steam from generation to distribution and various types of end-use equipment.

Figure 14.2 INDUSTRIAL APPLICATIONS OF STEAM

2.0 PRINCIPLES OF STEAM GENERATION AND STEAM TABLES As heat energy is added to water, the temperature of the water increases until the boiling point is reached (refer to Figure 14.3). This heat, which increases the water temperature, is called sensible heat . When the boiling point is reached, the addition of further heat causes some of the water to change to steam, but the steam and water mixture remains at the boiling point temperature. At atmospheric pressure the boiling point of water occurs at 100EC. The heat which converts the water to steam at a constant boiling temperature is called latent heat . When the steam has been fully vaporized at the boiling temperature, it is called dry saturated . This means that there are no droplets of moisture within the steam vapour. steam When water is heated at a pressure above atmospheric, the boiling point will be higher than 100EC and the sensible heat will be greater. For every pressure there is a corresponding boiling temperature, and at this temperature the water contains a fixed, known amount of heat. As indicated in Figure 14.4, the greater the pressure, the higher the boiling temperature and heat content.


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Module 14 - Steam Generation & Distributi on ....

Figure 14.3 ILLUSTRATION OF CHANGE OF STATE

The unit of heat energy in the SI system is the J o u l e . Steam Tables (Figure 14.5 presents an extraction from the Steam Tables in Appendix C) are used to establish the energy content of water and steam. The use of steam tables is helpful in analyzing the operating effectiveness of a boiler plant. Enthalpy is the expression used to identify the energy content of the water, steam and water mixture or steam on a unit mass basis.

Figure 14.4 TEMPERATURE - ENTHALPY DIAGRAM


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Under the enthalpy heading in Figure 14.5, there are three columns; enthalpy of the liquid (hf), enthalpy of evaporation (hfg ) and enthalpy of steam (hg ). <

E n t h a l p y o f li q u i d (h f ) is a measure of the amount of heat energy

contained in one kg of water at a specific temperature. <

E n t h al p y o f ev ap o r at io n ( h fg ) (correctly called the latent heat of

vaporization) is the quantity of heat energy required to convert one kg of water to one kg of steam at a given pressure. <

E n t h al p y o f s te am ( h g ) is the total heat contained in dry saturated steam

at a given pressure. This quantity of energy is the sum of the enthalpy of liquid (h) f and the amount of energy required to evaporate one kg of water at the saturation temperature (hfg ).

Figure 14.5 EXTRACTION FROM STEAM TABLE Gauge Pressure bar

Absolute Pressure bar

........ 0.95 1.00 1.05 ........ 8.90 9.00 9.10

Temperature

EC

Specific Enthalpy Water (hf ) kJ/kg

Evaporation (hfg) kJ/kg

Steam (hg) kJ/kg

Specific Volume Steam (Vg) m3/kg

1.963 2.013 2.063

119.63 120.42 121.21

502.2 505.6 508.9

2203.5 2201.1 2199.1

2705.7 2706.7 2708.0

0.901 0.881 0.860

9.913 10.013 10.113

179.53 179.97 180.41

761.1 763.0 765.0

2016.6 2015.1 2013.5

2777.7 2778.1 2778.5

0.196 0.194 0.192

........

The three previous figures for enthalpy may be expressed in an equation hg = hf + hfg

where hg = Enthalpy of dry saturated steam (kJ/kg) hf = Enthalpy of liquid (kJ/kg) hfg = Enthalpy of evaporation (kJ/kg)

Most boilers are designed to produce dry saturated steam. !

Examples From Steam Table (Ap pendix C)

The steam tables can be used to compare the energy content of dry saturated steam at two pressures of 200 and 1,000 kPa (absolute). Note that the steam tables give properties based on absolute values of pressure. The steam pressure on normal gauges is usually registered in bars. The zero bar indicated on the gauge is 1.013 bar below atmospheric pressure.


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Absolute Pressure

= Gauge Pressure (kPa) + 101.325 kPa = Gauge Pressure (bars) + 1.013 bar

where 1 bar = 100 kPa

‚

‚

200 kPa (2 bar abs) Dry Saturated Steam

Sensible heat (hf ) Latent heat of evaporation (hfg )

= 505.6 kJ/kg = 2,201.1 kJ/kg

Total heat (hg )

= 2,706.7 kJ/kg

1,000 kPa (10 bars abs) Dry Saturated Steam

Sensible heat (hf ) Latent heat of evaporation (hfg )

= 763.0 kJ/kg = 2,015.1 kJ/kg

Total heat (hg )

= 2,778.1 kJ/kg

From the foregoing enthalpy comparison it should be noted that, as steam pressure increases, the amount of sensible and total heat increases and the latent heat decreases. !

Steam Quality

The enthalpy cannot be directly obtained from steam tables when there is moisture in the steam. The steam quality can be expressed in equation form SteamQuality

'

MassofSteamVapour MassofSteamVapourandWaterMixture

A steam quality of 0.98 means that there is 2% moisture in the steam. The heat content of 1,000 kPa and 0.98 quality steam can be calculated using steam tables : Sensible heat Latent heat (2,015.1 x 0.98)

= 763.0 kJ/kg = 1,974.8 kJ/kg

Total heat (hg )

= 2,737.8 kJ/kg

The heat required to eliminate moisture is: = 2,778.1 - 2737.8 = 40.3 kJ/kg


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!

Superheated steam

As long as water is present, the temperature of saturated steam will correspond to the figure indicated for that pressure in the steam tables. However, if heat transfer continues after all the water has been evaporated, the steam temperature will again rise. The steam is then called "superheated" and this superheated steam can be at any temperature above that of saturated steam at corresponding pressure. Saturated steam will condense readily an any surface which is at lower temperature, so that it gives up the enthalpy of evaporation which, as we have seen, is the greatest proportion of its energy content. On the other hand, when superheated steam gives up some of its enthalpy, it does so by virtue of a fall in temperature. No condensation will occur until the saturation temperature has been reached. The rate at which we can get energy to flow from superheated steam is often less than we can achieve with saturated steam, even though the superheated steam is at a higher temperature. Superheated steam, because of its non-condensing property, is the natural first choice for power steam requirements, while saturated steam is ideal for process and heating applications.

3.0 BOILER HOUSE OPERATION 3.1

Energy Flow and Balance The three sources of boiler heat energy input are the fuel, feedwater and combustion air.

Figure 14.6 BOILER ENERGY FLOW

!

Fuel

The major energy source is from the fuel which can be expressed in terms of MJ/m3 for gas, MJ/L for oils and MJ/kg for coal and other solid fuels. In the case of Residual Fuel Oil (RFO), it is necessary to heat the oil in the storage tank sufficiently to permit pumping and then to heat it further before the burner. SADC Industrial Energy Management Project

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The thermal energy of the oil as it is delivered to the boiler should be added to the higher heating value (HHV) of the oil to represent the total fuel energy input. !

Feedwater

The feedwater temperature must also be considered as part of the energy input (i.e. higher temperature of feedwater requires less heat energy from the fuel to be converted to steam). The feedwater temperature can be used to determine this heat input level. The energy content of the feedwater is the enthalpy (hf ) as determined in steam tables corresponding to the feedwater temperature. !

Combustion Air

Combustion air is normally drawn from within boiler plant, but may be ducted from outside and heated with steam. Higher combustion air temperature will reduce the energy input required from the fuel.

3.2

Burners Burner design varies according to the type of fuel and the application objectives, but they must all do the following: < < < <

!

Direct fuel to the combustion chamber. Direct air to the combustion chamber. Effectively mix the fuel and air. Once the burner has been ignited it must continue to ignite the incoming fuel.

Oil Burners

Oil must be atomized and simultaneously mixed with air to sustain combustion. An oil burner consists of a central tube with an atomizing device at the end, and a register that surrounds the barrel and serves to distribute the flow of air to the boiler. Mechanical oil burners can be used to atomize No.2 or RFO oil, but the pressure must be very high to obtain acceptable turndown. The t u r n d o w n r a t i o is the ratio of the maximum to minimum fuel flows which can produce satisfactory combustion. An example of the pressure difference for a 5:1 turndown would be that a mechanical oil burner would require 4,500 kPa oil pressure whereas a steam atomized burner would only require 650 kPa pressure for the same turndown. Most No.6 (RFO) oil burners use steam-assisted atomizers where steam is mixed with the oil in the atomizing tip to break up the oil particles. This type of burner requires less oil pressure than the straight mechanical type and has better turndown ratio of up to 5:1.


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!

Natural Gas Burners

Natural gas mixes readily with air. The ring-type gas burner consists of a circular barrel ringed with multiple outlet ports. The register surrounds the barrel with air. Many boilers are equipped with a combination of natural gas and oil burners with the second fuel used as a back up to the prime fuel.

!

Pulverized Coal Burners

The barrel of a pulverized coal burner consists of a large diameter steel tube fitted with internal distribution vanes. The coal and hot primary air, which were previously mixed in the pulverizer, are introduced tangentially to the barrel to impart a strong rotation in the barrel. Adjustable inlet vanes also impart a rotation to the preheated secondary air entering the register. The degree of air and fuel swirl, coupled with the shape of the burner throat, establishes a recirculation pattern extending into the combustion chamber. Once the coal is ignited, the combustion heat in the furnace stabilizes the flame.

3.3

Boilers Steam is generated in boilers, i.e. pressure vessels where water is turned into steam on a continuous basis by application of heat. !

Boiler Types < <

<

Low pressure boilers operate in the range up to 3 bars pressure. Medium pressure boilers operate in the range up to 10 to 15 bars pressure, mainly in industrial processes. High pressure boilers operate above 15 bars, mainly in power generating applications.

The principal boiler types are the firetube, watertube, coiltube and electric. ‚

Firetube boilers

These are essentially shell-and-tube heat exchangers where combustion gas passes through tubes which are immersed in water. Firetube boilers usually burn natural gas or oil, although some, with a firebox type of combustion chamber, can be installed on top of a coal or wood stoker. They can generate dry saturated steam or hot water up to a maximum of 1,700 kPa (17 bar) gauge. The output ranges from 350 to 28,000 MJ/h. Boilers are shop assembled and delivered with integral burner, forced draft fan and controls. Since firetube boilers operate at low pressures, the boiler water temperature is correspondingly low, ranging from 110 to 200EC. By ensuring that the SADC Industrial Energy Management Project

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combustion gas contacts as much of the heat transfer surface as possible, the flue gas temperature can be reduced to within 50EC of the boiler temperature. This minimizes the flue gas heat loss and can result in boiler efficiencies in excess of 80%. ‚

Watertube boilers

The watertube boiler is capable of firing any type of combustible material in a wide range of capacities. Watertube boilers operate at pressures up to 30,000 kPa (300 bars) and can produce steam at up to 565 EC. Watertube boilers pass the combustion gases around tubes carrying water. This type is generally used in sizes from 7,000 kg/h to about 95,000 kg/h as manufactured units and in larger sizes with field-erected assemblies. Normally the steam drum of the watertube boiler contains a sophisticated system of steam/water separators to produce high quality steam at the outlet. Steam with less than 1% entrained water droplets are common for such boilers ‚

Coiltube boilers

Coiltube boilers are essentially forced circulation water tube boilers which generate steam from water circulated through a single tube or multiple coiled tubes surrounding the combustion chamber. This type is used in sizes up to about 10,000 kg/h. Coiltube boilers require a continuous forced circulation of water through the tubes and usually have an inertial type steam/water separators at the steam outlet. The quality of steam leaving the boiler depends on the efficiency of the separator and the steam may contain up to 10% water droplets by weight. ‚

Electric boilers

Hot water or steam can be generated in boilers where water is heated electrically with immersion coils. Electric boilers are more efficient than fuel fired boilers because there are no flue gas losses to the stack. Electrical energy is often not competitive with other fuels, but this should be checked particularly with respect to off-peak tariffs. New three-pass firetube boilers, with ratings of 1,600 to 16,000 MJ/h are available with electric heaters as well as gas or oil burners. These boilers are considerably more expensive, but provide the flexibility of fuel switching with the use of gas during the day and electricity at night.

!

Basic Components of A Boiler <

Internal :

- Water space - Steam space

<

External:

- Combustion chamber - Heating surfaces - Grate surfaces for wood and coal burning


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- Burner - Combustion air blower - Ignition and atomizer - Feed pumps - Injectors

3.4

<

Operating Controls:

-

Fuel-air flow controls Fuel-air pressure controls Fuel-air temperature controls Ignition control Mud blow down Continuous blow down

<

Safety :

-

Steam safety valve Hi-Low water control Ignition proving Combustion proving Fusible plug

Feedwater Treatment The quantity and quality of the condensate returned to the boiler plant will directly affect the extent and cost of the feedwater treatment. The feedwater conditioning and handling system must continuously satisfy certain conditions to discourage operating problems. The feedwater treatment and equipment may include the following: < <

<

<

<

<

Filters to remove suspended matter from condensate. De-aerating heater to preheat the boiler feedwater and remove the dissolved oxygen, carbon dioxide and other non-condensible gases. Water softener and/or demineralizers to remove scale forming dissolved solids from raw feedwater required to make up lost condensate. In demineralization, ion exchange removes ionized mineral salts. Demineralization can yield pure water required by high pressure boilers. Blow down tanks to allow blow down of sediment from the boiler caused by chemical treatment of make-up water. Dealkalizers remove the alkalinity in the form of bicarbonates from raw water make up. Bicarbonates break down into carbonates and CO2 . CO 2 leaves the boiler with the steam and forms acidic condensate, which causes corrosion of condensate piping system. Chemical treatment to: - keep suspended and dissolved solids and sludge in a form that can be removed through blow down. - reduce corrosion by preventing the build up of oxygen and carbon dioxide in the water. - control pH. - prevent foaming conditions within the drum which allows water carryover with the steam.


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Sample specification for feed water and boiler water for low and medium pressure boilers: Feed water:

Total hardness as CaCO3 pH value Dissolved oxygen Silica as SiO2 Total dissolved solids

10 ppm 8.5 to 9.5 0.1 0.0 100 to 500 ppm

Boiler water:

Total alkalinity Caustic alkalinity pH value Phosphates Total dissolved solids Silica

!

700 ppm 350 ppm 11 to 12 30 to 50 ppm 1,000 to 2,000 ppm 40 max.

.Condensate Tanks Condensate tanks or receivers are designed to hold the returned condensate and treated make-up water. They can be pressurized or vented to the atmosphere. Vented tanks lose from 2 to 10% of the heat in the condensate as flash steam. The cost of the treated boiler water that must be replaced and the pumping cost must also be considered. A pressurized tank avoids these losses, but a low pressure steam system must be available to absorb the vented steam. An alternative is to cool the condensate with cold make-up water to reduce or eliminate flashing of the condensate.

!

Flash Tanks

Flash tanks are used to separate condensate and flash steam that is produced when condensate is reduced in pressure. This may be done so that plant discharges can be reduced to atmospheric pressure before being disposed as effluent or to produce quantities of low pressure steam for heating or deaerating purposes. If a plant discharge produces a consistent flow of significant quantities, some attempt should be made to recover heat by using the flash steam to heat domestic or service water.

3.5

Boiler Plant Monitoring The term monitoring refers to the act of observing the overall boiler plant equipment operation plus the actual measurement of data available. Regular monitoring of the plant variables is an essential part of consistently maintaining energy efficient conditions. Combustion is a complex process which is dependant on a large number of interacting boiler plant variables. Thus, the possibility for combustion air and fuel conditions or equipment to change and alter the combustion efficiency must always be anticipated. A significant large change would be obvious, but a


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gradual change might only be detected quickly as a result of good consistent monitoring habits by operating personnel. There is a variety of monitoring equipment available to assist operating personnel in the task of ensuring that efficient operation is being achieved. <

<

<

!

An annunciator is an alarm system that brings undesirable conditions to the operator's attention by means of audible and/or visual signals. Combination of indicators and recorders are used to display important information. Totalizers are often provided for steam and fuel flows so that the direct boiler efficiency can be calculated.

Daily Boiler Log Book

The boiler room variables should be routinely recorded in the boiler log book. A sample " Daily boiler log sheet" is provided in Figure 14.7. Each company can design it's own log book to record the vital parameters of steam generation peculiar to it's production needs. For large steam producing facilities comprehensive log books are commercially available. For a medium size operation the boiler log book should include: <

F u e l d a t a : fuel consumption, fuel pump discharge temperature and

pressure. <

< <

< < <

3.6

C o m b u s t i o n : stack temperature, ambient temperature, combustion

efficiency. Steam: steam pressure, steam flow if available. Feedwater: feedwater temperature, flow, water quality, pump discharge pressure. Make-up: water softener, amount, water quality, temperature. Blow down: manual daily discharge, continuous percentage discharge. : water quality. Bo iler water

Boiler Plant Efficiency !

Energy Balance

BoilerThermalEfficiency(%)

E IN

'

BoilerHeat Output (E OUT )

'

BoilerHeat Input (E IN )

Steam BlowdownLoss (CombustionEfficiency %RadiationLoss)

BoilerPlantEfficiency(%)


%

&

'

SteamProduced TotalEnergyInputIncludingAuxilliarie

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!

Mass Balance

Feedwater = Steam Produced + Blowdown Feedwater = Make-up Water + Condensate Returned Condensate Returned = Feedwater - Make-up Water Condensate Lost = Make-up Water - Blowdown Condensate Returned = Steam Produced - Condensate Lost

!

Example

A packaged watertube steam boiler supplies high and low temperature heat for the plant manufacturing processes. ‚

Operational data < < < < < < < < < < < < < < < <

‚

Boiler Output Operating Pressure Operating Time Feed Water Temperature Ambient Temperature Flue Gas Temperature Fuel Oil HHV Cost of Fuel Combustion Efficiency, measured Boiler Radiation Losses, estimated Percentage Blowdown Make-up Water, metered Make-up Water Temperature Cost of Water including Sewage Charges Cost of Water Treatment Cost of Electricity

... ... ... ... ... ... ... ... ... ... ... ... ... ... ...

10,000 kg/h 1,500 kPa 6,000 h/y 105EC 20EC 280EC 38.68 MJ/L $0.50 /L 78% 3% 8% ... 3 000 L/h 15EC $2.00 /m3 $1.00 /m3 $0.10 /kWh

Mass balance Feed water

= steam + blow down = 10,000 + 800 kg/h = 10,800 kg /h

Condensate Return = Feedwater - Make-up Water

= 10,800 - 3,000 kg/h = 7,800 kg /h Condensate Lost


= Make-up Water - Blowdown = 3,000 - 800 kg/h = 2,200 kg /h

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‚

Energy balance:

E IN

'

Steam BlowdownLoss (CombustionEfficiency %RadiationLoss) %

&

where = m x (h1 - h2 )

Steam

where

m = steam mass (10,000 kg/h) h1 = total enthalpy in steam (2,793.7 kJ/kg) h2 = enthalpy of feedwater (440.4 kJ/kg) = 10,000 x (2793.7 - 440.4) = 23.533 GJ/h

Blowdown

= m x (h3 - h4 )

where

m = blowdown mass (800 kg/h) h3 = enthalpy boiler water (856.3 kJ/kg) h4 = enthalpy of make-up (62.8 kJ/kg) = 800 x (856.3 - 62.8) = 0.635 GJ/h

E IN

'

Steam BlowdownLoss (CombustionEfficiency %RadiationLoss) %

&

'

'

23.533 0.78

% &

0.635 0.03

32.224GJ/h

ThermalEfficiency

SteamProduced FuelEnergyInput

'

'

23.533GJ/h 32.224GJ/h

'

73 %

Boiler plant efficiency includes energy input from auxiliaries items such as lights, blowers, pumps, etc. The total electrical load is assumed to be 20 kWh x 3.6 MJ/kWh = 72 MJ/h or 0.072 GJ/h. This energy input is negligible in comparison with the other items listed above but not so on an annual cost basis. The total energy input is 32.296 GJ/h (32.224 + 0.072). BoilerPlantEfficiency


'

SteamProduced TotalEnergyInput

'

23.533GJ/h 32.296GJ/h

'

72.9%

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Figure 14.7 DAILY BOILER LOG BOOK Date

Shift

Shift-in-Charge

Fuel Consumption kg/hr

Blowdown at Time

1 2 3 Time

Fuel Pump Return Discharge Oil Pressure Pressure kg/cm2 kg/cm2

Fuel Oil Temp E

C

Boiler Steam Pressure kg/cm2

Feedwater pump Discharge Pressure Pump No.1


Pump No.2

Stack Temp

E

C

Ambient Temp

E

C

Boiler Water Level

Water Water Remarks Quality Softener Checked Regeneat rated at

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4.0 STEAM DISTRIBUTION SYSTEM Saturated steam should be distributed with a minimum loss of heat, a minimum pressure drop and at a velocity not exceeding 25 m/s, to minimize the damage to the system due to the water-hammer effect. The distribution system should ideally include, steam separators, traps with strainers and air vents. It should have an adequate slope in the direction of the flow to ensure removal of the condensate and air. It is usually economical to distribute steam at boiler working pressure with pressure reduction, if required, immediately ahead of the user equipment.

Figure 14.8 STEAM SEPARATOR AT TAKE-OFF FROM BOILER

4.1

Steam Circuit The steam generated in the boiler must be conveyed through pipework to the places where its heat energy is required. There will be one or more main pipes or "steam mains" from the boiler in the general direction of the steam using plant. Smaller branch pipes then carry steam to the individual pieces of equipment. Figure 14.8 shows a typical piping arrangement with steam separator on the line from the crown valve and condensate being carried away through strainer, float trap and check valve to the condensate tank. In Figure 14.9, the problem of water hammer conditions resulting from sagging pipes and condensate collection are displayed. When the boiler crown valve is opened steam immediately rushes from the boiler into and along the main. The pipework is cold initially and so the heat transfer takes place from the steam. The condensate forming in the pipes falls to the bottom and is carried away by the steam flow to the low point of the main or other branch pipes. When the valve on a piece of steam using equipment is opened, steam enters and gives up its enthalpy of evaporation to warm up the equipment and to bring it up to the operating conditions.


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For an efficient operation, the condensate formed in both the steam distribution pipework and in the process equipment must be quickly returned to the feedwater tank for reuse.

Figure 14.9 WATER PICK-UP AT LOW POINT

4.2

Steam Traps The purpose of installing the steam traps is to obtain fast heating of the product and equipment by keeping the steam lines and equipment free of condensate, air and non-condensible gases. A steam trap is a valve device that discharges condensate and air from the line or piece of equipment without discharging the steam. When starting up the equipment and steam systems, lines and equipment are full of air which must be flushed out. During continuous operation a small amount of air and non-condensible gases, which enter the system with the feedwater, must also be vented. All traps should be protected from dirt and scale by installation of a strainer. Unless removed, this material may cause the trap to jam in an open position, allowing the free flow of steam into the condensate collection system. Traps are also available with check valve features to guard against condensate backflow. The many different types of steam traps manufactured operate by sensing the difference between steam and condensate using one or more of the three basic physical properties. When classified according to these operating principles, each design has advantages and limitations which must be considered when selecting a steam trap for a specific application. The three basic types of steam traps are as follows: < < <

Mechanical (Density operated) Thermostatic (Temperature operated) Disc and Orifice (Kinetic energy operated)

Figure 14.10 displays operating characteristics of basic steam trap types.


Page 17 of 32


Figure 14.10

OPERATING CHARACTERISTICS OF a)

TYPE

b)

OPERATION

c)

OPERATING LOAD FACTOR

d)

AIR HANDLING CAPACITY

e)

AIR LOAD FACTOR

f)

g)

BALANCE PRESSURE THERMOSTATIC

LIQUID EXPANSION THERMOSTATIC

Intermittent action. Wide open when cold allowing free discharge of air incondensibles and cool condensate. Condenate at or near steam temperature evaporates volatile filling in element, closing trap. Cooling of condensate aallows filling to condense and trap opens. Once trap is closed, opening may be delayed in hot locations.

Continuous discharge at approximately constant temperature below 100 EC. Wide open when cold, allowing free discharge of air and cool condensate. Condensate approaching 93EC (maximum discharge temperature) expands oil filling of element, throttling condensate flow.

3:1

2:1

Extremely high - in fact these traps are often used as thermostatic air vents.

Good. Air is freely discharged on start-up and during running tends to reduce condensate temperature.

1:1

1:1

APPLICATION LOAD FACTOR

In hot locations opening may be delayed by slow cooling of condensate. (2:1)

Pressure increase raises condensate temperature, roughly balancing increased discharge rate. Pressure decrease reduces condensate temperature tending to increase valve opening and capacity. Extremely hot locations reduce cooling rate of condenate. (2:1)

OVERALL LOAD FACTOR

Normal Load Factor = cxexf = 3x1x1 = 3:1 Hot Locations = 3x1x2 = 6:1

Normal Load Factor = cxexf = 2x1x1 = 2:1 Hot Locations = 2x1x2 = 4:1


Page 18 of 32


(Figure 14.10 cont'd)

BASIC STEAM TRAP TYPES INVERTED BUCKET

FLOAT & THERMOSTATIC

THERMO-DYNAMIC

Intermittent discharge. Trap is closed by air or steam filling inverted bucket. Air and/or steam leaks away through vent hole in bucket which loses bouyancy and sinks, opening valve. Condensate is discharged and process repeats.

Continuous discharge. Condensate raises float, opening valve the required amount to release condensate as fast as it enters. Intermediate response to change of load and pressure differential.

Intermittent condensate flows freely through trap until temperature approaches saturation, when disc valve is snapped shut by flashing condensate. Condensate at inlet causes control chamber pressure to fall and trap opens. Rapid response to condensate.

2:1

1:1

1.25 : 1

Air is by-passed on start-up by a balanced pressure thermostatic air vent. During running, air entering the trap cools air vent, which opens to release air.

Air must be released through main valve seat, slowing the flow of condensate when amount of air is excessive.

As air can close the trap, it can seriously reduce discharge capacity.

2 : 1 to 3 : 1

1.2 : 1

Normal Excessive Air

1:1 1.5 : 1

Not affected by high ambient temperatures. (1:1)

The trap has no closed period unless load falls to zero. Unaffected by ambient temperatures. (1.2:1)

Extreme ambient temperature may delay opening. (1.5:1)

Normal Load Factor = cxexf = 2x2x1 = 4:1 Excess Air = 3x 1 x 2 = 6 : 1

Normal Load Factor = cxexf = 1 x 1.2 x 1 = 1.2 : 1 Heavy Load Variation = 1 x 1.2 x 1.2 = 1.5 : 1

Normal Load Factor = cxexf = 1.25 x 1 x 1 = 1.25 : 1 Excessive Air = 1.25 x 1.5 x 1 = 1.9 : 1 Excessive Heat = 1.25 x 1 x 1.5 = 1.9 : 1 Excessive Heat & Air = 1.25 x 1.5 x 1.5 = 2.8 : 1


Page 19 of 32


4.3

Flash Steam Recovery Flash steam is released from hot condensate when its pressure is lowered, rather than by further addition of heat. Even water at ordinary room temperature of 20EC would boil if the pressure was lowered below 0.02 bar abs - and water at 170EC will boil at any pressure below 6.9 bar g. The steam released by the flashing process is just the same as the steam released when heat is added to saturated water while a constant pressure is maintained. For example if a load is applied to a boiler, and the boiler pressure drops a little, then some of the water content of the boiler flashes off to supplement the steam which is being produced by the supply of heat from the boiler fuel. Because it is all produced in the boiler, the steam is all referred to as "live steam". Only when the flashing takes place at relatively low pressure, as at the discharge side of steam trap, is the name flash steam used. Unfortunately, this usage has led to the erroneous conclusion that flash steam is in some way different from and less valuable than, so called live steam. In any system where it is sought to maximize efficiency - which should mean in all systems - flash steam will be separated from the condensate. It can then be utilized at low pressure, to help supply any low-pressure load. Every kilogram of flash steam used in this way is a kilogram which does not have to be supplied directly by the boiler. It is also a kg which will not be vented to the atmosphere. The reasons for the recovery of flash steam are just as compelling, both morally and economically, as those for recovering condensate. !

How much flash steam?

To make use of flash steam, we need to know much of it will be available. The quantity is readily determined by calculation, or it can be read from simple charts or tables. As an example, let us consider the jacketed vessel shown in Figure 14.11. The condensate enters the trap as saturated water, at a gauge pressure of 7 bar and temperature of 170.5EC. The enthalpy of this saturated water is 721.4 kJ/kg. After passing through the steam trap, the pressure on the condensate is the return line pressure, i.e. 0 bar gauge. At this pressure, the enthalpy of saturated water is 419 kJ/kg and the temperature is 100EC. If a kilogram of saturated water at 0 bar gauge were supplied with an additional 302.4 kJ/kg (721.4 - 419) then this enthalpy would evaporate some of the water. The enthalpy of evaporation at 0 bar gauge is 2,257 kJ/kg. An addition of 302.4 kJ must evaporate 302.4 / 2,257 kg of steam from the water. Equally, when one kg of condensate containing 721.4 kJ/kg reaches the return line where the pressure is 0 bar g, it has surplus of 302.4 kJ above the enthalpy of saturated water that it can hold. The same proportion of 302.4 / 2,257kg of flash steam will be evaporated. Thus :


Page 20 of 32


Enthalpy of saturated water at 7 bar = 721.4 kJ/kg Enthalpy of saturated water at 0 bar = 419.0 kJ/kg Surplus energy = 302.4 kJ/kg Enthalpy of evaporation at 0 bar Proportion of flash steam

= 2,257 kJ/kg = 302.4 / 2,257 = 0.134 =

13.4%

If the steam-using equipment were condensing 250 kg of steam, then the amount of flash steam released by the condensate at 0 bar gauge would be : = 0.134 x 250 kg/h = 33.5 kg/h

5.0 END-USE EQUIPMENT Normally, saturated steam is used in industrial and space heating applications. Two basic types of heating occur in steam heating equipment. These are direct and indirect heating. With direct heating , the product or material to be heated is in direct contact with the steam and in most cases, no condensate is recovered. An example of direct heating is the heating of the liquid by directly injecting it with steam. The steam and condensate mix with the product. If steam injection is used to heat an aqueous solution an allowance has to be made for the diluting effect of the condensate. Indirect heating separates the steam and product. In most cases the condensate

from the steam is recovered and reused for boiler feed water or other hot water requirements. Examples of indirect heating include: < < <

Steam-to-liquid heat exchangers Product heating in storage tanks Air heaters

It must be noted that situations may occur where condensate is not recovered from indirect heated equipment. In instances such as heating vegetable oils, glucose or preheating fuel oils in heat exchangers, a failure in the heat exchanger could allow the heated material to mix with the condensate. If this condensate was then returned as boiler feedwater, this condensate would foul the internal heat transfer surfaces of the boiler. The three basic types of indirect steam heated equipment are the steam coil, jacketed vessels and heat exchangers. Normally for jacketed vessels or steam coils the liquid to be heated is not flowing. For heat exchangers the steam and liquid are flowing.


Page 21 of 32


Figure 14.11 TYPICAL STEAM HEATED EQUIPMENT IN INDUSTRY FIXED GRAVITY JACKETED KETTLE: A p p l i c a t i o n : Meat Packing

Paper Sugar Fruit Vegetable Operation: Steam introduced around the kettle transfers heat to the product. Depends on type of Pressure: product. P r o b l e m s : Trapped air Product - Gravity drain Draining: STEAM JACKETED PRESS: A p p l i c a t i o n : Molded Plastics (Records)

Rubber Products Tires Plywood Laundry Flat Work Operation: See sketch. Depends on type of Pressure: product. Each platten individually Draining: trapped. DRYERS: Rotating Drums - Rotary Cookers with PRODUCT INSIDE A p p l i c a t i o n : Meat Packing

Chemical Process Food Operation: Low RPM (1-10). A revolving cylinder drained with a syphon - an internal syphon surrounded by steam. Some condensate flashes back to steam due to the steam jacketed syphon pipe and syphon lifting during evacuation. 0 - 1000 kPa Pressure: Syphon drainage. Draining:


Page 22 of 32


Figure 14.11 (Cont'd) TYPICAL STEAM HEATED EQUIPMENT IN INDUSTRY DRYERS: Rotating Steam Filled Drums with PRODUCT OUTSIDE A p p l i c a t i o n : Paper - Making Paper

Textile - Drying and Conditioning Fabrics Plastics Food Laundry Operation: 1-2 RPM 25 m/s surface velocity Ranging from subPressure: atmospheric to 1380 kPa. Diam. Range 0.15 - 4.3 m. Draining: Syphon drainage required. DIRECT STEAM INJECTION INTO PRODUCT CHAMBER: A p p l i c a t i o n : Sterilization Autoclaves

Rubber Plastics Retorts for cooking food in already sealed cans Operation: See sketch. Depends on type of Pressure: product. See sketch. Draining:

!

Industrial Steam Heating Equipment

Samples of typical industrial steam heated equipment with a brief description of operating characteristics are shown in Figure 14.11. !

Unit Heaters

The unit heaters are heat exchangers that use steam or hot water forced through metal tubes, to heat air blown over the tubes. (Refer to Figure 14.12.) Normally the tubes are finned or passed through thin metal plates to increase the surface area and heat transfer rate. A low room temperature signal from a thermostat starts the fan and blows air over the heated surfaces, increasing the heat transfer rate to the air. As soon as the thermostat senses the desired temperature, the fan shuts off.


Page 23 of 32


Figure 14.12 TYPICAL UNIT HEATER

6.0 ENERGY MANAGEMENT OPPORTUNITIES 6.1

Housekeeping Opportunities !

Boiler House - Operation < <

<

< <

< <

<

!

Regularly check water treatment procedures. Maintain the total dissolved solids (TDS) of the boiler within recommended limits, for the pressure range of the boiler. Operate at the lowest steam pressure or hot water temperature that is acceptable to the boiler design and distribution system requirements. Condition fuel for optimum combustion. Minimize load swings and schedule demand where possible to maximize the achievable boiler efficiencies. Regularly check the efficiency of the boilers. After the boiler tune-up start recording and analyzing the flue gas temperature for signs of heat transfer surfaces fouling. Regularly monitor the boiler excess air.

Boiler House - Maintenance < < < <

< < <

Keep burners in proper adjustment. Check for and repair leaking flanges, valve stems and pump glands. Maintain tightness of all air ducting and flue gas breeching. Check for hot spots on the boiler casing that may indicate deteriorating boiler insulation that should be repaired during the annual shutdown period. Keep fireside surfaces of the boiler tubes clean. Replace and repair missing or damaged insulation. Replace boiler observation or access doors and repair any leaking door seals.


Page 24 of 32


!

Steam Distribution System < < < < <

!

End-Use Equipment < < < < < <

< <

6.2

Establish steam trap maintenance and procedures. Check and correct steam and condensate leaks. Train operating personnel. Check control setting. Shut down steam and condensate branch system when not required.

Seal leaks at valves, fittings and gaskets. Repair damaged insulation Maintain equipment strainers and traps. Clean heat transfer surfaces. Ensure that steam quality is adequate for the application. Ensure that the steam pressure and temperature ranges are within the tolerances specified for the equipment. Ensure that the traps are correctly sized to remove all the condensate. Ensure that the heating coils are sloping from the steam inlet to the steam trap to prevent the coil flooding with condensate.

Low Cost Opportunities !

Boiler plant < <

< <

!

Steam Distribution System < < <

< < <

!

Install performance monitoring equipment. Relocate combustion air intake to the top of the boiler house to use the heated air and save energy. Recover blowdown heat. Reduce boiler excess air where possible.

Recover condensate where economically feasible. Overhaul the pressure reducing stations. Reduce the direct use of steam where possible by using the heat exchanger. Remove unused steam and condensate pipes. Reduce system pressure where possible. Relocate the equipment to shorten the length of piping.

End-Use Equipment < <

<

Shut down equipment when not required. Provide lockable type covers for control equipment such as thermostats to prevent unauthorized tampering. Operate equipment at or near capacity whenever possible. Avoid running multiple units at reduced capacity.


Page 25 of 32


<

6.3

Add thermostatic air vents.

Retrofit Opportunities !

Boiler House < < < <

!

Steam Distribution System < < < < < < <

!

Install economizer. Install preheater. Upgrade burner. Install tubulators in fire tube boiler.

Institute steam trap replacement program. Optimize pipe sizes. Recover flash steam. Eliminate steam use where possible. Stage the depressurization of condensate. Recover heat from condensate. Meter all steam and condensate flows.

End-Use Equipment <

< <

Convert from direct to indirect steam heated equipment and recover condensate. Modify process, if possible, to stabilize steam or water demand. Evaluate waste water streams leaving a facility for heat recovery opportunity.

7.0 WORKED EXAMPLES 7.1

Relocate Combustion Air Intake (Boiler House) The combustion air intake can sometimes be relocated to the top of the boiler house to use heated air and thus save energy. A boiler firing No.2 oil uses 14,500 kg/h of air at 20EC average temperature. Installation of the duct to the top of the boiler house increases the average air temperature to 30EC. The specific heat of air is 1.01 kJ/kg.


Page 26 of 32


The recovered heat (Q) is: Q = m x C p x )T = 14,500 kg/h x 1.01 kJ/kg C x (30 - 20) C = 146,450 kJ/h E

E

Assuming the boiler operates 6,000 hours per year and fuel costs $5 /GJ, the annual fuel cost saving is: '

'

146,450kJ/h x 6,000h/y x $5/GJ 1,000,000kJ/GJ $4,390peryear

Assuming the cost of ducting is $5,000, the simple payback period (SPB) is: SPB

7.2

'

$5,000 $4,390

'

1.1years

Replace Or Repair Leaking Traps (Steam Distribution System) During the steam trap survey it was noted that a steam trap with 3.17 mm orifice on a 205 kPa(abs) heating system did not appear to be operating properly. Further investigation indicated that the trap was stuck in the full-open position allowing the steam to flow into the condensate return line. From Figure 14.13, it was established that this condition would allow the trap to pass 6.2 kg of steam per hour. The heating system in this facility was used 3,600 hours per year and the cost of steam was estimated to be $22 per 1,000 kg. The steam loss from the leaking trap is: = 6.2 kg/h x 3,600 h/y = 22,320 kg/yr

The cost of energy associated with this steam loss is: = 22,320 kg/yr x $0.022 /kg = $491 /year

Assuming the replacement cost of the new trap, including labour, is $90, the simple payback period is: SPB

'

$ 90 $491

'

0.18years (2months)

If the system pressure was higher or the orifice larger, the quantity of lost steam would greatly increase as would the cost of the money being lost.


Page 27 of 32


Figure 14.13 STEAM LOSS THROUGH ORIFICE DISCHARGING TO ATMOSPHERE Orifice Diam (mm)

15

30

60

100

150

300

500

700

900

1400

1700

1900

0.8 1 2

0.18 0.28 1.14

0.21 0.32 1.28

0.25 0.40 1.58

0.32 0.49 1.98

0.40 0.62 2.47

0.63 0.99 3.95

0.95 1.48 5.93

1.27 1.98 7.91

1.58 2.47 9.88

2.37 3.71 14.8

2.85 4.45 17.8

3.16 4.94 19.8

3 4 5

2.56 4.55 7.10

2.89 5.14 8.03

3.56 6.33 9.88

4.45 7.91 12.4

5.56 9.88 15.4

8.90 15.8 24.7

13.3 23.7 37.1

17.8 31.6 49.4

22.2 39.5 61.8

33.4 59.3 92.7

40.0 71.2 111

44.5 79.1 124

6 7 8

10.2 13.9 18.2

11.6 15.7 20.6

14.2 19.4 25.3

17.8 24.2 31.6

22.2 30.3 39.5

35.6 48.4 63.3

53.4 72.6 94.9

71.2 96.9 127

89.0 121 158

133 182 237

160 218 285

178 242 316

9 10 11

23.0 28.4 34.4

26.0 32.1 38.9

32.0 39.5 47.8

40.0 49.4 59.8

50.0 61.8 74.7

80.1 98.8 120

120 148 179

160 198 239

200 247 299

300 371 448

360 445 538

400 494 598

12 12.7

40.9 45.8

46.3 51.8

56.9 63.8

71.2 79.7

89.0 99.6

142 159

213 239

285 319

356 399

534 598

640 717

712 797

7.3

Steam Loss (kg/h) when steam gauge pressure (kPa) is:

Shut Down Equipment (End-Use Equipment) During the plant survey it was noted that a steam heater supplying hot air to a drying tunnel was operating even though the tunnel was not in use. Subsequent investigation established that the heater system ran for 8,760 hours per year, although the tunnel only operated 6,000 hours per year. Steam used for the heater was 689 kPa (gauge) dry and saturated. Steam flow to the unit was measured at 200 kg/h. The cost of steam was $0.022 /kg. The annual reduction in steam usage is: = (8,760 - 6,000) h/yr x 200 kg/h = 552,000 kg/yr

The annual cost saving is: = 552,000 kg/yr x $ 0.022 /kg = $12,144 /yr

It was decided to install a relay and solenoid valve to shut off the steam when the drying tunnel was not in operation. Estimated cost to supply and install the hardware was $ 500. The simple payback period is: SPB

'

$500 $12,144

'


0.04years (15days)

Page 28 of 32


8.0 ASSIGNMENT The purpose of this assignment is to assess the operation of the boiler house, the conditions of the steam distribution network and the steam end-use equipment. After accomplishing this task, explore the potential of improving the efficiency of the steam generation, reducing the steam distribution losses and updating the operation of the steam using equipment. Specific tasks in this assignment include:

!

Assess the Boiler House Records <

Examine the l o g b o o k data. Does it describe all the regular maintenance and operating procedure data required for a good maintenance and energy management program? If there is no log book maintained in the boiler house establish one, using as a guide the log book sample in this module.

<

Review the f u e l c o n s u m p t i o n r e c o r d s . (Part of Module 2 assignment.)

<

Check the steam produc tion record s . Is there a steam meter installed in the boiler house? If so, does it record the total steam production or the steam production from each boiler? Has the meter been calibrated recently? If there is no steam meter, consider having one installed. (A more economical approach may be to install a feedwater meter as described below.)

!

<

Check the boiler feedwater record s . Is the water metered per boiler or for the total plant? Does the feedwater quantity correlate with steam production? If the feedwater is not metered, arrange to have one installed.

<

Check the make-up water record s . If the make-up water is not metered arrange to have one installed.

<

Check the condensate return. How much condensate is being returned? What temperature is the returned condensate? What is the temperature of the water in the feedwater tank?

<

Check the feedwater testing proc edures and establish feedwater analysis records where none exists.

<

Check the make-up water testing procedures and establish water analysis records where none exists.

Determine Boiler Combustion and Radiation Losses <

Analyze the flue gas and calculate the combustion efficiency. (Part of Module 13 assignment.)


Page 29 of 32


<

!

!

Calculate radiation losses . Should the boiler insulation be repaired or replaced? (Part of Module 13 assignment. Also refer to Module 8.)

Calculate Boiler Plant Performance <

Complete a m a s s b a l an c e of the boiler plant system.

<

Complete an e n e r g y b a l a n c e of the boiler plant system.

<

Calculate the thermal efficiency and the overall efficiency for the boiler plant using the procedure described in this module.

Check the Steam Distribution System <

Check the insulation on the steam distribution lines. Should the insulation be repaired, replaced or upgraded? (Part of Module 8 assignment.)

<

Check the insulation on the condensate return lines. Should the insulation be repaired, replaced or upgraded? (Part of Module 8 assignment.)

<

Check the insulation on the feedwater tank. Should the insulation be repaired, replaced or upgraded? (Part of Module 8 assignment.)

<

Observe and record any steam leakages around valve stems, fittings or piping. Make repairs as required.

<

Survey and record the condition and operation of the steam traps . Have faulty traps repaired immediately.

<

Review existing program for maintaining steam traps . Is the program adequate?

<

Calculate applicable losses due to insufficient insulation of the steam

pipes and losses due to leaking joints and faulty steam traps.

!

Check Steam End-Use Equipment <

Make sure the equipment is operating near design capacity and that the is according to the equipment specification. quality of steam

<

Examine the p r o d u c t i o n s c h e d u l e for the steam operated equipment.

<

Check the shu t-off valves on the equipment for leaking particularly when the equipment is not in production.


Page 30 of 32


!

Assess Potential Energy Management Measures <

Identify potential improvements to the entire steam generating, distributing and end use systems.

<

Calculate the cost saving benefits that would be achieved by each measure. Estimate the c o s t o f i m p l e m e n t in g the energy efficiency improvements.

<

<

Prepare a one page summary proposal for each recommendation, stating initial conditions, proposed improvements, cost savings, cost of implementation and simple payback. Use the Energy Management Opportunities form from Module 3 or similar.

9.0 SUMMARY - Module 14 In this module you learned about: L

Principles of Steam Generation,

L

Steam Tables,

L

Boiler House Operation,

L

Boiler Plant Monitoring,

L

Boiler Plat Efficiency,

L

Steam Distribution,

L

Steam Heated Equipment.

You should now be able to perform the following tasks: L

Assess the Operation of the Boiler House in Your Plant,

L

Evaluate the Boiler House Performance,

L

Identify Potential Improvements,

L

Assess the Benefits, Cost and Simple Payback Period for Each Measure.


Page 31 of 32

Steam Generation & Distribution.pdf

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