ENERGY SAVING INENERGY SAVING IN STEAM GENERATION AND STEAM GENERATION AND

TRANSPORT IN FOOD TRANSPORT IN FOOD INDUSTRYINDUSTRY

B. K. KumbharB. K. Kumbhar

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IntroductionIntroduction

• Energy – Important• Sources Exhausting at rapid rate prices

increasing day by day • Energy cost 5% of total production cost • Neglected

HOT WATER OR HOT WATER OR STEAM?STEAM?

More accurate control without costly control equipmentsMore accurate control without costly control equipments Efficient processing and high standard of hygiene with Efficient processing and high standard of hygiene with

maximum fuel economymaximum fuel economy Thermal efficiency of hot water boilers is more and fuel Thermal efficiency of hot water boilers is more and fuel

requirement is about halfrequirement is about half Savings in water, maintenance and labour requirements,Savings in water, maintenance and labour requirements, Maximum recovery is possibleMaximum recovery is possible Lower reconstruction and capital costsLower reconstruction and capital costs Lower instrumentation costsLower instrumentation costs Obviation of the use of chemicalsObviation of the use of chemicals High heat and moisture release is eliminated resulting a High heat and moisture release is eliminated resulting a

simple ventilation systemsimple ventilation system Improvement in safety Improvement in safety

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Boiler Input-OutputBoiler Input-Output

Fuel Air WaterFuel Air Water

Boiler* Combustion* Heat Transfer

Steam Flue gas Blowdown

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1. 1. STEAM GENERATIONSTEAM GENERATION 1.1 1.1 FuelFuel 1.2 1.2 AirAir 1.3 1.3 WaterWater

A. Treatment of waterA. Treatment of water B. Preheating of feed waterB. Preheating of feed water C. Use of condensate as feed waterC. Use of condensate as feed water

1.4 1.4 Flue gasFlue gas a) Temperature of flue gasa) Temperature of flue gas b) Quantity of flue gasb) Quantity of flue gas c) Condition of heat transfer surface in the boilerc) Condition of heat transfer surface in the boiler

1.5 1.5 BlowdownBlowdown 1.6 1.6 Radiation and convection lossesRadiation and convection losses

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1.1 1.1 FuelFuelQuality of Fuel- Quality of Fuel- Sulphur, Moisture contentSulphur, Moisture content Fuel oilFuel oil

Burners – Atomization Burners – Atomization - Air - Specific heat is less - Air - Specific heat is less - Steam – Specific heat is more- twice- Steam – Specific heat is more- twicePreheatingPreheating

CoalCoalPulverizationPulverization

Natural gasNatural gas

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1.2 1.2 AirAir

QuantityQuantitySufficient amount Sufficient amount

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1.3 1.3 WaterWater

Treatment of waterTreatment of waterCa, Mg salts- scale formation- less heat transferCa, Mg salts- scale formation- less heat transfer

0.79 mm – Increased fuel consumption – 7%0.79 mm – Increased fuel consumption – 7%2.82 mm – 16%2.82 mm – 16%Oxygen and CO2, Low pH- Corrosion & ErosionOxygen and CO2, Low pH- Corrosion & Erosiontreatment of feed water outside the boiler treatment of feed water outside the boiler within the boiler (internal treatment)within the boiler (internal treatment) chemicals which remove hardness or scale forming materials that chemicals which remove hardness or scale forming materials that

can not be removed by filtration. can not be removed by filtration. Oxygen and carbon dioxide - vacuum deaerators Oxygen and carbon dioxide - vacuum deaerators

steam scrubbing deaeratorssteam scrubbing deaerators

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Water contdWater contd

Preheating of feed waterPreheating of feed waterTemperature of feed water- efficiencyTemperature of feed water- efficiency

6 C increase- 1% fuel saving6 C increase- 1% fuel saving Economizer for preheatingEconomizer for preheating

Use of condensate as feed waterUse of condensate as feed water• Reduction in use of chemicals for water softeningReduction in use of chemicals for water softening• Preheating is preventedPreheating is prevented• Reduced water requirementReduced water requirement

Temperature increase from 15.5 to 35 C with Temperature increase from 15.5 to 35 C with 100% condensate return reduced 4.2% fuel100% condensate return reduced 4.2% fuel

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1.4 1.4 Flue gasFlue gasLoss of energy> 18%Loss of energy> 18%

Temperature of flue gasTemperature of flue gas• Temperature 70 C more than water temperature Temperature 70 C more than water temperature • Clean surfaceClean surface• Use of economizer- 10% fuel saving- payback period Use of economizer- 10% fuel saving- payback period

1 year1 year• Reduction of 22 C 1% increase in efficiencyReduction of 22 C 1% increase in efficiency

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Quantity of flue gasQuantity of flue gasProper air-fuel ratioProper air-fuel ratio

TemperatureTemperatureBarometric pressureBarometric pressureHumidityHumiditySpecific gravity and viscosity of the fuel oilSpecific gravity and viscosity of the fuel oil

Table 1 Suggested levels of excess airTable 1 Suggested levels of excess airFuelFuel BurnerBurner Excess air, %Excess air, %Coal Coal Spreader stoker Spreader stoker 30‑6030‑60Fuel oilFuel oil Register typeRegister type 5‑105‑10

Multifuel typeMultifuel type 10‑2010‑20Natural gasNatural gas Register typeRegister type 5‑105‑10

MultifuelMultifuel 7‑127‑12  Reduce excess air Reduce excess air Keep COKeep CO22 level above 13% or O level above 13% or O22 level below 3.5% 3% change in CO level below 3.5% 3% change in CO22 level increases 4% in efficiency 3-5% saving in automated level increases 4% in efficiency 3-5% saving in automated control devices control devices

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Condition of heat transfer surface in the boilerCondition of heat transfer surface in the boiler Clean surface – more heat transfer Clean surface – more heat transfer Regular cleaning of all surfaces Regular cleaning of all surfaces

Standstill for few months corrosion of boiler due Standstill for few months corrosion of boiler due to residual moisture. Remove residual moisture to residual moisture. Remove residual moisture with dryain with dryain

Residual moisture in dry air <30%Residual moisture in dry air <30%

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1.5 1.5 BlowdownBlowdown

AffectsAffects Make up water - Make up water - Heat loss in blowdown Heat loss in blowdown Chemicals requirement Chemicals requirement

Frequency Frequency Quantity Quantity Heat recoveryHeat recovery

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Advantages of automatic Advantages of automatic BlowdownBlowdown

Discharge less heat Discharge less heat Reduces treatment chemicals Reduces treatment chemicals Decrease make up water Decrease make up water About 20% saving from changeover About 20% saving from changeover

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1.6 1.6 Radiation and Radiation and convection lossesconvection losses

Significant loss if not insulatedSignificant loss if not insulated 1.5% loss in well insulated 1.5% loss in well insulated capacity utilization. capacity utilization. Less- Radiation loss more Less- Radiation loss more Boiler operation few hours a dayBoiler operation few hours a day

Use boiler stack damper Use boiler stack damper Close boiler house doors & windowsClose boiler house doors & windows

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2.2. STEAM TRANSPORTSTEAM TRANSPORT

2.1 2.1 Quality steamQuality steam 2.2 2.2 InsulationInsulation 2.3 2.3 Correct pipingCorrect piping 2.4 2.4 Strainers, steam traps Strainers, steam traps and and

steam separatorssteam separators

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2.12.1 Quality steamQuality steam Steam Quality Steam Quality Amount of water droplets present Amount of water droplets present Quality steam Quality steam Better heat transfer Better heat transfer Long life of the system Long life of the system Dry, Clean, free from non condensable gases, right pressure and right temperature Dry, Clean, free from non condensable gases, right pressure and right temperature Dirty steamDirty steam• Erode and corrode value Erode and corrode value • Clogging of ports body Clogging of ports body • Leakage through valvesLeakage through valves Non condensable – limit steam flow less heat transfer Non condensable – limit steam flow less heat transfer • 0254 moss film thickness – 3.3m of cu panel 0254 moss film thickness – 3.3m of cu panel • Carbon di-oxide-carbonic acid- corrosion Carbon di-oxide-carbonic acid- corrosion • Oxygen – accelerates corrosionOxygen – accelerates corrosion

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2.22.2 InsulationInsulation Personal protection Personal protection Condensation prevention Condensation prevention Process temperature control Process temperature control Heat loss prevention Heat loss prevention

Poor insulation – Up to 50% heat loss Poor insulation – Up to 50% heat loss To reduce loss of heat To reduce loss of heat

Economic thickness – cost of fuel & insulating material installation cost, Economic thickness – cost of fuel & insulating material installation cost, pipe size, annual hours of operation, boiler efficiency, pay back period. pipe size, annual hours of operation, boiler efficiency, pay back period.

Replace damaged insulation Replace damaged insulation Insulate values and flanges – uninsulated flange heat loss from 60 cm of Insulate values and flanges – uninsulated flange heat loss from 60 cm of

untagged pipe. untagged pipe.

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2.32.3 Correct pipingCorrect pipingPipe size Pipe size * Amount of steam to be transported * Amount of steam to be transported

* Pressure * Pressure

Oversize pipe Oversize pipe Pressure drop increases, Pressure drop increases, Temperature. Decreases – heat transfer reduction Temperature. Decreases – heat transfer reduction

Length Length Just sufficient Just sufficient Excess length & redundant piping increases loss of heat Excess length & redundant piping increases loss of heat condensation of stem, corrosion of pipe condensation of stem, corrosion of pipe

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2.4 2.4 Strainers, steam traps & Strainers, steam traps & steam separators steam separators

StrainersStrainers Upstream of values and steam trafs to protect from clogging with dust & dire. Upstream of values and steam trafs to protect from clogging with dust & dire.

Steam trapsSteam traps to remove condensate and non condensable correct size of steam trap. to remove condensate and non condensable correct size of steam trap.

Steam separatorSteam separator To get drier steam – water dropter To get drier steam – water dropter Direction of flow path to changed Direction of flow path to changed Accumulated water droplets sent to stem traps Accumulated water droplets sent to stem traps Near a point of usage Near a point of usage

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3. STEAM FOR PROCESSING3. STEAM FOR PROCESSING

Quality steam Quality steam Efficient processes and equipment Efficient processes and equipment Collecting condensate Collecting condensate

Boiler feed water Boiler feed water Cleaning the equipment Cleaning the equipment Heating process streamsHeating process streams

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4. 4. WHAT CAN BE DONE?WHAT CAN BE DONE? a. Calculate the total heat, Q, present in the fuel by knowing the a. Calculate the total heat, Q, present in the fuel by knowing the

calorific value (cv) of the fuel and quantity of fuel (m) used.calorific value (cv) of the fuel and quantity of fuel (m) used. b. Calculate the process heat requirement. This will include heat b. Calculate the process heat requirement. This will include heat

required for heating, evaporation and drying duties as the case may be.required for heating, evaporation and drying duties as the case may be. Overall thermal efficiency of plant Overall thermal efficiency of plant Calculate total heat required in the plant Calculate total heat required in the plant Calculate total heat available in the fuel Calculate total heat available in the fuel

Boiler efficiency – 80% Boiler efficiency – 80% Transport efficiency – 95% Transport efficiency – 95% Process/thermal efficiency – 80% Process/thermal efficiency – 80% No. of plants – 61% No. of plants – 61%

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Boilers Boilers

Large boiler – 75-85% efficiencyLarge boiler – 75-85% efficiency

Gas fired boilers – 92 % efficiency Gas fired boilers – 92 % efficiency

Efficient boiler operation and maintenance saving up to 35%Efficient boiler operation and maintenance saving up to 35%

Energy savings up to 20% in new boilersEnergy savings up to 20% in new boilers

Efficiency Efficiency Combustion efficiency - how efficiently the boiler burns the fuel Combustion efficiency - how efficiently the boiler burns the fuel Steady – state efficiency – under full load Steady – state efficiency – under full load Seasonal efficiency – over the entire heating season Seasonal efficiency – over the entire heating season

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Improving Efficiency Improving Efficiency

Energy saving devices Energy saving devices

- Economizer - Economizer

- Condensate recovery - Condensate recovery

- Air preheaters - Air preheaters

- Turbulators - Turbulators

- Oxygen trim controls - Oxygen trim controls

- Load controls - Load controls

- older pneumatic control system- older pneumatic control system

- Analog control systems - Analog control systems

- Digital computer based distributed control systems - Digital computer based distributed control systems

Modern, multiple burner control and trim control – 3-5% saving Modern, multiple burner control and trim control – 3-5% saving

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Selecting a new Boiler SystemSelecting a new Boiler System

Replace old biter – 15 years old with a high efficiency model – save up to Replace old biter – 15 years old with a high efficiency model – save up to 35%35%

Older boilers oversized, inefficient Older boilers oversized, inefficient Multiple boiler systems more efficient than single boilers Multiple boiler systems more efficient than single boilers Pay back period 2-4 years Pay back period 2-4 years

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Fire Side Maintenance Fire Side Maintenance Minimize excess air – Regular monitoring (weekly) of gas oxygen or Minimize excess air – Regular monitoring (weekly) of gas oxygen or

carbon dioxide content carbon dioxide content Keep heat transfer surfaces cleanKeep heat transfer surfaces clean

- Soot build up on tubes – insulation- Soot build up on tubes – insulation

- Elevated stack temperature - Elevated stack temperature

Water side Maintenance Water side Maintenance Reduce scale formationReduce scale formation Scale build up – loss by as much as 10-12% 1/8 inch. – 2-3% loss in boiler Scale build up – loss by as much as 10-12% 1/8 inch. – 2-3% loss in boiler

efficiency efficiency

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Reduce boiler pressure – Reduction in fuel consumption and stack Reduce boiler pressure – Reduction in fuel consumption and stack temperatures temperatures

Insulate Boiler and boiler piping 2.5 cm insulation – 80-90% reduction in Insulate Boiler and boiler piping 2.5 cm insulation – 80-90% reduction in heat lossheat loss

Optimize Boiler blowdown watersOptimize Boiler blowdown waters Blowdown heat recovery Blowdown heat recovery

- Blowdown rat4e 4-8% of total steam generated - Blowdown rat4e 4-8% of total steam generated - AS high as 10%- AS high as 10%

Repair of steam leaksRepair of steam leaksSteam leaks develop around valve stems pressure regulators Steam leaks develop around valve stems pressure regulators

and pipe joints and pipe joints Small leak represents a significant loss of energySmall leak represents a significant loss of energy

Repair of leak have a short pay back (2-3) months. Repair of leak have a short pay back (2-3) months.