The new scheme of preliminary treatment of makeup water of various technological purposes at parallel work of turbine units with heat release to external consumers has been offered. Variants of work of one of the existing and offered schemes are compared and analyzed. Use of the developed scheme in comparison with the existing one allows cutting fuel consumption up to 15...16 % or 31 thousand tons of equivalent fuel per heating season

Kalugin, B. F.

Zalomikhin, V. A.

Electronic archive of Tomsk Polytechnic University

Rational use of energy carriers (fuel) is one of themost principle tasks of FEC (fuel and energy complex)enterprises including TS (thermal stations). Fuel factorof FEC consumptions is one of the main constituents ofthe enterprise supplied product rate (heat and electricenergy). The problem of cost cutting (including fuelconsumptions) for manufacturing and supplying theproduct becomes the most urgent problem due to formation of new conditions on the market NOREM (newwholesale electricity and power market).One of the existing schemes (Scheme № 1) of preparing make up water and heat supply with delivery water to one of the largest operating TPP in Siberia havingthe open water intake system and vapor supply to industrial consumers without dry return is introduced inFig. 1. The new scheme (Scheme № 2) is introduced inFig. 3. Considerable losses of heat carrier (delivery water and vapor of industrial consumers) which should befulfilled at TPP are typical for this scheme of TPP.Vapor heatexchanger apparatuses – 1, 2 (1 – boilermake up heater, 2 – heat network make up heater) areof wide use in the existing schemes, Fig. 1 (Scheme№ 1) of heating make up water for chemical cleaning.These heaters are necessary for heating and withstanding the make up water temperature on the required level 26±1 °С. The reduced temperature of make up water is accepted for the examined station and depends onprocesses carried out in the shop of water chemical purification. River water taken directly from the river bedserves for compensation of working substance leakage.The temperature of water taken from the river dependson a season and falls within the range of +1...+6 °С forthe considered heating season of the examined station.Use of a condenser – 3 of turbine unit operating ondegraded vacuum is possible for preliminary heating ofmake up water taken from the river. The whole requiredflow of make up water or its part may pass through thecondenser – 3. The values of make up water flow passing thought the condenser or round about it as well asthe make up water temperature after the condenser – 3and on bypass line of the condenser – 3 characterizethe make up water temperature before vapor heatexchange devices – 1, 2. The make up water consumption through – 1, 2 and the heating value from temperature before heating units to 26±1 °С forms thermal load of the vapor heat exchange devices. Vapor is suppliedto heating units – 1, 2 from the heatcogeneration turbine unit TU2 (of the type Т258,8) having one controlling steam extraction with control range0,12...0,25 MPa. After heating to the required values thewater taken from river for compensation of leakage ofvarious engineering purpose the make up water is sent tothe shop of water chemical purification.The make up water returned from the shop of waterchemical purification is warmed to the necessarytechnological temperature values by the steam TU1(this aggregate is not shown in the considered schemes,Fig. 1 and 3) and is not examined as it has constant values (thermal load) without influence on operation ofthe considered schemes. Besides thermal load of heating units – 1, 2 the turbine unit TU2 carries thermal load conditioned by heating the return delivery water carried back from consumers with the temperature tоб (temperature of the return delivery water according to thetemperature chart of heat release, Fig. 2, Curve – 1) ortоб.ф (actual temperature of return delivery water obtained by data processing of the studied station, Fig. 2,Curve – 2 has the value higher than tоб) to the temperature tо.o. (temperature of the mixture obtained by heatinga part of consumption of the returned delivery water inheating units – 5, 6, and their partial bypassing if necessary, Fig. 2, Curve – 3). The use of bypass line – 7 of theheating units is conditioned by the necessity ofwithstanding temperature of heating water according tothe temperature chart in the range of outside air hightemperatures.Besides TU2, the turbine unit TU3 (of the typeТ1158,8) having two steam extractions with the control range of 0,05...0,25 MPa was used for covering thespecified thermal loads conditioned by consumption ofthe carried back returned delivery water Gоб=1028 kg/s.Drain water Gк.j of the heating units – 4, 5 is returned tothe thermal diagram TA3 and condenser of the heatingunits – 1, 2 and – 6 to the thermal diagram ТА2.In respect to the studied station the make up waterconsumptions for heating network amount to 278 kg/s(heating network makeup), for compensation of losseswith vapor of industrial extraction and losses in the station cycle 125 kg/s (boiler makeup). All calculations forvariable conditions of turbine unit operation [2] by thediagrams of Fig.1 and Fig. 3 were carried out with thecondition of working by thermal schedule with miniPower engineering53UDC 621.165ANALYSIS OF HEATCOGENERATION TURBINE UNIT OPERATION IN SCHEMES OF PRELIMINARY TREATMENT OF MAKEUP WATERV.A. Zalomikhin, B.F. KaluginTomsk Polytechnic UniversityЕmail: zva_tes82@mail.ruThe new scheme of preliminary treatment of makeup water of various technological purposes at parallel work of turbine units with heat release to external consumers has been offered. Variants of work of one of the existing and offered schemes are compared and analyzed. Use of the developed scheme in comparison with the existing one allows cutting fuel consumption up to 15...16 % or 31 thousandtons of equivalent fuel per heating season.mum ventilating vapor pass in the low pressure part(LPP) of the turbine units TU2 and TU3. Carrying outthe calculations the restrictions for TU3 by thermal load in 653 GJ/h, by maximum consumption of deliverywater 833 kg/s through the heating units – 4, 5 were accepted; the restrictions were accepted according to thedata of manufacturing plant.Fig. 1. Scheme of preliminary water treatment № 1 Fig. 2. Temperature chart of heat release Content of the proposed changes consists in substitution of steam heatexchange devices – 1, 2 by watertowater heatexchange devices (WWHD) – 8, 9(Fig. 3). The notations of the elements in Fig. 3 correspond to the notations of Fig. 1. WWHD for heating makeup water, running to the shop of water chemical purification, to the required values as a heating medium, usethe return delivery water supplied to the station fromconsumers with tоб or tоб.ф. As a result of makeup waterheating the return delivery water is cooled up. The cooled up delivery water (the temperature of the return delivery water is lower than the values of temperature chartand if the actual temperature of the return delivery water is higher than the temperature chart then the use ofScheme № 2 in Fig. 3 allows approximating it considerably to the design values) enters the twostep heating ofTU3. As a result of redistribution of thermal and electricloads between TU2 and TU3 conditioned by decrease oftemperature of the return delivery water entering the heating units – 4, 5 of TU3 (at one and the same carryingcapacity of the heating units of TU3 – 4, 5 the temperature decrease of the return delivery water relative tothe considered diagram promotes the increase of thermal and as a result the electric load of turbine unit TU3having a more economic two step scheme of heat release [4], [5]). Lower temperature of the return deliverywater at the two step scheme promotes the decrease ofpressure in a lower hot water converter – 4 (pressuredecrease in a lower heating extraction) that increaseselectric generation by steam supplied to this heatingunit; besides it promotes the decrease of passing vaporGчнд through the fully closed regulating orifice into LPPand condenser. It is appropriate to apply the Scheme№ 2 in the whole range of outside air temperature+8...–40 °С Fig. 9.The result of the proposed changes is the decrease ofthermal and electric energy of TU2 (having less economy onestep scheme of heat release in comparison withtwostep scheme of heat release of TU3) or its full exclusion from the scheme at sufficiency of the deliveredheat from TU3 at high temperature of the outside air.The total electric power generated by turbine units TU2and TU3 in the diagrams № 2 is higher than at operation by the diagram № 1 at the equal heat release.Change of water consumption by flows, the condenser– 3 and its bypass allow changing thermal load falling toWWHD (maximum thermal load corresponds to fullcondenser bypass – 3, i.e. the direct water supply to theheating units – 1, 2 or – 8, 9 from river). The higherthermal load of WWHD, the higher the fuel economy bythe new scheme.Fig. 3. Scheme of the preliminary water treatment № 2 Additionally generated electric power on thermalconsumption promotes the displacement of electric energy generation by condensation cycle of the consideredstation or another source. In order to determine the fuel economy due to additionally generated electric powerBulletin of the Томsк Pоlytеchnic University. 2007. V. 311. № 454applying the new Scheme № 2 Fig. 3 the specific fuelconsumption of the displaced source of power supply246 g.edu.f./(kW.h) and 550 g.edu.f./(kW.h) are accepted. In order to determine the annual fuel saving at useof the proposed Scheme № 2 the calculations on theexamined schemes functioning in temperature rangefrom +8 to –40 °С in increments of 5 from 0 °С werecarried out. Hourly economy of the equivalent fuel wasdetermined by calculation results for each temperaturevalue tн.в..According to [1] and average number of standing foreach design temperature value for the region of heat station arrangement the annual fuel saving is determined.The curves allowing us to determine the annual fuel saving when using the Scheme № 2 depending on thethermal load value falling to WWHD both for tоб (Curve– 2 for the displaceable energy supply source with specific fuel consumption 550 g.edu.f./(kW.h) and Curve –4 for the displaceable energy supply source with specificfuel consumption 246 g.edu.f./(kW.h)), and for (Curve– 1 for the displaceable energy supply source with specific energy consumption 550 g.edu.f./(kW.h) and Curve – 3 for the displaceable energy supply source withspecific energy consumption 246 g.edu.f./(kW.h)) areintroduced in Fig. 4. In the region limited by the Curves– 2, 4 (Fig. 4), and Curves – 1, 3 (Fig. 4) the annual fuel saving for TPP with specific fuel consumption forelectric energy generation in the range of246...550 g.edu.f./(kW.h) may be determined.Fig. 4. Curves of annual fuel saving Introduction of the Scheme № 2 promotes:1) redistribution of loads (thermal, electric) betweenaggregates operating in parallel, increasing the loadof one of them and decreasing the load of the otherless saving aggregates. At low thermal loads it allowsexcluding completely the operation of one of theconsidered aggregates;2) pressure decrease in lower heat extractions (at two ormore stages of the main heating of makeup water)that promotes the increase of electric energy generation at thermal consumption;3) decrease of thermal losses in the condenser of turbine unit. Owing to the pressure loss in lower heat extraction at fully closed regulating orifice the vaporpassing into LPP and condenser decreases considerably;4) reduction of specific fuel consumption for generation and delivery of electric energy at support withthermal energy in the required quantity;5) displacement of condensation generation of electricenergy properly at the considered station or in electric power system;6) exception of the steam heatexchange devices andpumps transferring the condensed water of heatingsteam of heating units – 1, 2 (Fig. 1).The results of operation of aggregates functioning inparallel by the existing studied scheme of heat station(widely used at TPP) and the proposed new scheme ofpreliminary makeup water treatment at heat release tothe consumers for the variant without heating makeupwater in the condenser – 3 and with thermal load fallingto WWHD Qввта=152 GJ/h depending on the outside airtemperature tн.в. are introduced in Fig. 5–9.Fig. 5. Characteristic of steam consumption in LPP of TU3 whenusing: 1) Scheme № 1; 2) Scheme № 2It is seen in Fig. 5 that steam consumption in LPP ofTU3 (Curve – 2) when using Scheme № 2 is lower thanat use of Scheme № 1 (Curve – 1).Fig. 6. Characteristic of pressure Рн.т. of lower heat extractionof TU3 at use of: 1) Scheme № 1; 2) Scheme № 2It is seen in fig. 6 that the pressure of the lower heatextraction of TU3 (Curve – 2) at use of Scheme № 2 islower than the pressure of lower heat extraction of TU3at use of Scheme № 1 (Curve – 1).It is seen in Fig. 8 that total electric power (Curve –2) generated by the turbine units TU2 and TU3 at use ofScheme № 2 is higher than the total electric power ofthe turbine units TU2 and TU3 at use of Scheme № 1(Curve – 1).00,050,10,150,20,25-40-35-30-25-20-15-10-50510t . .,. .,120123456789-40-35-30-25-20-15-10-50510t . .,G , /21Power engineering55Fig. 7. Characteristic of the release thermal loads Qт from TU2and TU3: 1, 3) turbine units TU3 and TU2, Scheme № 1;2, 4) turbine units TU3 and TU2, Scheme № 2Fig. 8. Characteristic of electric loads Nэ to TU2 and TU3: 1,2) total load of TU2 and TU3, Schemes № 1 and № 2; 3,5) load of TU3 and TU2, Schemes № 1; 4, 6) load of TU3and TU2, Scheme № 2As it is seen in Fig. 9 the values of specific fuel consumption for electric energy generation at use of Scheme № 2 in the whole range of outside air temperature israther lower that at when using Scheme № 1. The abrupt change of the Curve – 1 at the outside air temperature –10 °С is conditioned by inclusion of turbine unitTU2 into the Scheme of heat release.Fig. 9. Characteristic of average weighted specific fuel consumption bэ by TU2 and TU3 for electric energy generation at use of: 1) Scheme № 2, 2) Scheme № 1Conclusion The new more saving scheme of makeup water preliminary treatment using the heat of the return deliverywater was developed for FEC enterprises on the basis ofTPP.Application of the new scheme allows decreasing fuel consumption to 15...16 % or 31 thousand tons of equ.fuel by heating season.The new scheme promotes the decrease of electricenergy cost by reducing specific fuel consumption.Using the new scheme promotes the improvementof ecological situation against the background of reducing the specific fuel consumption for electric energygeneration.The obtained efficiency data indicate the appropriateness of applying the developed scheme at the FEC enterprises on the basis of TPP and promote further expansion of applying schemes using the return deliverywater as a heating medium.150160170180190200210220230240-40-35-30-25-20-15-10-50510t . .,b ,. . ./( * )12020406080100120-40-35-30-25-20-15-10-50510t . .,N ,1243560100200300400500600700-40-35-30-25-20-15-10-50510t . .,Q , /2134Bulletin of the Томsк Pоlytеchnic University. 2007. V. 311. № 456REFERENCES1. Sokolov E.Ya. Industrial heating and heating system. – The 7th issue,stereotype. – Moscow: MEI Press, 2001. – 472 p.: ill.2. Girshfeld V.Ya. TPP operating conditions. – Moscow: Energiya,1980. – 288 p.: ill.3. Kirsanov I.N. Condensing units. – Moscow: Energiya, 1965. – 376 p.4. Benenson E.I., Ioffe L.S. Heating steam turbines. – Moscow: Energiya, 1976. – 264 p.: ill.5. Antonova A.M., Vagner M.A., Kalugin B.F. General power engineering. – Tomsk: TPU Press, 2003. – 387 p.Received on 23.11.2006

Analysis of heat-cogeneration turbine unit operation in schemes of preliminary treatment of makeup water

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Analysis of heat-cogeneration turbine unit operation in schemes of preliminary treatment of makeup water

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