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    Waste Heat Sources in Sugar Factory and Their

    Utilization for Cooling Condenser Water

    By

    R.K.Kulkarni Dr. S.P.S. Rajput

    Research Scholar Asst. ProfessorMechanical Engineering Department

    M.A.N.I.T.

    Bhopal(MP)

    India

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    Overview of Presentation

    Introduction

    Identifying Waste Heat Sources

    Present System for Cooling Condenser Water

    Proposed Cooling System Model

    Working of Proposed System Benefits of Proposed System

    Conclusions

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    Introduction Sugar Industry- Second Largest processing industry

    Stages in Sugar Manufacture-Extraction of Juice

    -Clarification-Evaporation and Concentration

    -Forming and separating crystals

    Energy Consumed- Mill Driving Turbines- Mechanical

    Driving auxiliary units- Electrical EnergyEvaporation and Concentration of juice- Heat Energy

    Ways to Conserve Energy

    1)Modernization of Old equipment/ machines

    2)Adding of new systems like- Spiral juice heaters, Condensate flashingsystem, Continuous vacuum pans, Auto feeding of bagasse

    3)Co generation.

    4)Appropriate insulation of equipments

    5)Efficient cooling system

    6)Waste heat recovery systems

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    Boilers40 T

    15 T

    15 T

    Power

    Turbines2000 kW

    1600 kW

    De Super heater

    I II III IV

    Boilers

    20 T15 T

    Feed Water Tank

    Mill Turbines

    375kW X 51500 kW X 1

    Common

    Header

    Spray Pond

    Jet Condenser

    Evaporator Bodies

    2 pumps

    124 kW

    3 pumps

    189 kW

    Fuel

    Blow

    down

    Fuel

    Flue Gas

    Hot Condensate

    Vapors

    Identification of Waste Heat Sources

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    Boiler Flue Gases

    Waste heat content of flue gases

    Q = 4.187K ((1-W) (1.4M-0.13) +0. 5) * tWhere

    Q = Amount of waste heat in flue gases kJ/kg of sugar

    K = k1*k2

    K1 = percentage of bagasse in cane = 28 % from data of factory (min value)K2 = Quantity of cane required to get unit quantity of sugar. =11 from data of

    factory

    W = moisture content in bagasse average = 50 % according to data in factory.

    M = ratio of actual air to theoretical air = 1.4

    t = temp of fine gases going to chimney = 180 deg C.Thus waste heat content in flue gases can be calculated as

    Q = (4.187)(0.28)( 11) ((1-0.5) (1.4*1.4-0.13) + 0.5 ) * 180

    Q =3285 kJ/kg of sugar

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    Boiler Blow down Water

    Blow down- To control the amount of TDS in the boiler water for smooth

    operationBlow down amount- varies form 2 to 3 % of evaporative capacity or steam

    generation rate.

    Heat content of blow down

    Q = Mb.Cb. TbQ = Heat carried in KJ/kg of sugar

    Mb = average quantity of blow down in kg/kg of sugar

    = 2.5 % of evaporative capacity of boiler (Steam Generated)

    = 0.025 of ( 50% of cane crushed)

    = 0.025 of (0.5 * 11) per kg of sugar

    Cb = Sp. Heat of water =4.187 kJ/kg K

    Tb = temp of blow down. = 340 deg C

    Q = 0. 025 (0.5 *11) * 4.187*340

    = 195.7 kJ/kg of sugar

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    Hot Water Overflow

    Condensate from I and II evaporator body is used as feed water.

    Condensate from III,IV body and pans is used as hot water for theprocess. Normally the condensate produced is more than that requiredfor the process. By measuring the excess quantity of hot water, heatcarried by excess water can be calculated.

    Q = Mc.Cc.Tc

    Mc = quantity of surplus condensate

    = Average 7.5% on cane

    = 0.075 * 11

    Cc = specific heat of hot water = 4.187 kJ/ kg K

    Tc = temp of hot water = 65 C

    Q = (0.075) (11) (4.187) (65)Q = 224.5 kJ/kg of sugar

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    Summary of Waste Heat Sources

    S.No. Source Heat Content

    kJ/kg of sugar

    1 Flue gases 3285

    2 Boiler blow down 195.7

    3 Hot water 224.5

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    IV

    BodyPans

    JetCondenser

    Spray Pond

    2 pumps

    124 kW

    3 pumps189 kW

    Vapors

    Hot water 40-

    45 deg C

    Cold water 30-35 deg C

    Present Cooling System

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    Present System of Cooling

    Vapors from multiple effect evaporator and vacuum pans enter the condensers

    at about 60-65 deg C The heat from vapors is absorbed by cold waterintroduced in the condenser. The temperature of this cold water is around 30-

    35 deg C. The heat exchange between vapors and water is affected by-

    1) Contact time of vapors with cold water

    2) Contact surface offered by cold water to vapors

    Water then flows out under gravity along with the condensed vapors at about

    40-45 deg C. The temperature of incoming and outgoing water changes

    according to ambient conditions.

    Warm water leaving the condenser flows to the spray pond by gravity channeland it is cooled with the help of spray nozzles. Cold water at about 30 to 35

    deg C returns through gravity channel and it is pumped to the condenser. Thus

    it is a closed system.

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    Limitations of Present System

    The power consumption for pumps- 313 kW

    Steam to Bagasse Ratio- 1.8 to 2

    Increase in temperature of incoming water affects condensation of vapors in

    condenser and in turn affects vacuum in evaporator body.

    Increase in boiling point in the body increases the steam and bagasse

    consumption.

    Large quantity of cooling water is needed.

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    Proposed System Model

    Boilers

    Flue gas

    ScrubbingSystem

    HeatExchanger

    Absorption

    Chiller

    Flue Gases Water

    Flue gases

    to chimney

    Hot Water

    Cold Water

    To condenser

    Hot water from

    condenser

    Water

    out

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    Proposed System

    Aim-Reduction in the inlet temp of cooling water by incorporating a vapor

    absorption unit which runs on waste heat in boiler flue gases. Components-

    1) Scrubbing system to remove suspended matter from hot flue gases.

    2) A heat exchanger between flue gas and water.

    3) Absorption cooling unit.4) Pumps and fans.

    The hot flue gases from boiler contain soot etc. Full scrubbing of gas is not

    needed at this stage and only large particles need be removed. The upper spraychamber is of standard construction for even distribution of working fluid.(scrubbing liquid return.)

    A cross flow heat exchanger or shell and tube heat exchanger will be suitablefor the heat exchange between gas and water.

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    A Typical Scrubbing System

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    Ranges and Capacities of Absorption Chillers

    Hot water driven Temperature Capacity Range

    Low Temperature 70-110 deg C 100-650 NTR

    Medium Temperature 110-150 deg C 100-1400 NTR

    High Temperature 150-199 deg C 100-1400 NTR

    Low Temperature 70-110 deg C 10-80 NTR

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    Proposed System

    Flue gases from boiler will be passed through a scrubbing system where the

    suspended matter and un burnt particles will be removed. Then this gas will be passed through a heat exchanger where the water will be

    heated by flue gases.

    This hot water will be then used as heat source for the absorption refrigeration

    system. The hot water from the condenser will be passed through theabsorption refrigeration machine where its temperature will be decreased.

    This cold water will be then passed to the condenser for cooling purpose. The

    low temperature hot gases can be then diverted towards chimney.

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    Benefits from Proposed System

    Proposed system will be able to cool the condenser cooling water tolower temperature.

    The power required for spraying the water will be saved. The power will berequired for pumping the condenser water through the absorption chiller andheat exchanger. It is proposed to estimate the saving in power by thisarrangement.

    It also expected because of low temperature of cooling water rate ofcondensation of cooling water will be more and it will create more vacuum inthe evaporator and pans. This will lower down the boiling point in theevaporator and it will reduce steam consumption and ultimately result in

    bagasse saving.

    As the particulate matter in gases is reduced due to scrubbing system, it willreduce the pollution at the factory site.

    As the temperature of cooling water is less the quantity of water required forcondensing vapors will also be less. This will result in saving of water whenthere is scarcity of water. Low boiling temperature will improve the quality of

    sugar.

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    Conclusions

    Energy audit is an important tool to identify the areas of energy conservation

    in sugar factory. Waste heat sources in sugar factory are- Boiler flue gases

    Boiler blow down

    Hot condensate

    Most important waste heat source- Boiler flue gas

    Boiler flue gas heat can be utilized to run an absorption chiller.

    The chiller will cool condenser water.

    The power required in spray pond can be reduced. There will be improvement in condensation of vapors in condenser.

    Low boiling point of juice in evaporator can save steam and bagasse.

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    Acknowledgements:

    1) The Malegaon Sahakari Sakhar Karkhana Ltd. Shivnagar , Tal. Baramati,

    Dist.Pune.2) Vasantdada Sugar Institute Manjari (bk) Pune.

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    References

    1) Jadhav M.G.2002, Some findings on heat energy audit for sugar factory, Cooperative Sugar33,635-642.

    2) Damodaran C., N.Thirurumorthy, P.Parthsarathy,2004, Energy audit in sugar industry- a passport toprosperity, proceedings of Annual Convention of the South Indian Sugarcane and Sugar TechnologistAssociation,97-104

    3) Valagadde S.A., C.G.Mane, M.S.Bashetti, 2002, Energy conservation measures at Shri Renuka SugarsLtd. Proc. of 34th annual convention of SISSTA at Banglore, 129-136

    4) Chitale M.A., Use of efficient cooling system in sugar industries and cogeneration power plants,proceedings of 8th joint convention of STAI, SISSTA, DSTA at Hyderabad, 13-15 Aug.2005, 109-119

    5) Lavarack B.P., J.J. Hodgson, R. Broadfoot, S. Vigh, J. Venning, 2004, Improving energy efficiency ofsugar factories, case study for pioneer sugar mill,International Sugar Journal 106, 337-342.

    6) Talbi M., B. Agnew, 2002, Energy recovery from diesel engine exhaust gases for performance

    enhancement and air conditioning,Applied Thermal Engineering 22 693-702.7) Stehlik Peter, 2007, Heat transfer as an important subject in waste to energy systems,Applied Thermal

    Engineering 27, 1658-1670.

    8) Bhatt M.S., N Rajkumar,2001, Mapping of combined heat and power systems in cane sugar industry,Applied Thermal Engineering,21, 1707-1709.

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    References contd..

    9) Lu Y.Z., R.Z.Wang, S.Jainzhou, Y.X.Xu, J.Y.Wu, 2004, Practical experiments or an

    adsorption air conditioner powered by exhaust heat from diesel locomotive, AppliedThermal Engineering, 24,1051-1059.

    10) Bhatt M.S.2000, Energy audit case studies I- steam systems, Applied Thermal

    Engineering, 20,285-296

    11) Hugot H.1986, Hand book of cane sugar engineering, 3rd ed, Elsevier Newyork.

    12) Ben-Shumen Dan, Philip Zacuto, Process for recovering heat from stack or flue gas,

    U.S.Patent # 4340572,

    13) Websites- www.thermax-usa.com

    www.sucrose.com

    www.powerengineering.ca

    www.epa.gov

    www.tsi.com

    www.walchand.com

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    Thank You