Mass flow of steam through condenser m k, kg/s

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1 UTICAJ KLIMATSKE KRIVE NA RADNI REŽIM TURBINE U TEC "BITOLA INFLUENCE OF CLIMATIC CURVE VALUES ON THE OPERATING REGIME OF THE TURBINE AT TPP "BITOLA" V. Mijakovski*, K. Popovski* *Faculty of Technical Sciences, University Sv. Kliment to Ohridski, Ivo Lola Ribar bb, 7000 Bitola, Macedonia

With an installed capacity of 675 MW and an annual output of around 4,6 GWh this plant obtains about 75%

2 INTRODUCTION Thermal Power Plant (TPP) Bitola is the largest electricity producer in the Republic of Macedonia. With an installed capacity of 675 MW and an annual output of around 4,6 GWh this plant obtains about 75% of Macedonia s electricity production. The plant consists of three blocks. The layout of objects in Thermal Power Plant Bitola is shown on Figure 1. Figure 1. Layout of objects in Thermal Power Plant Bitola

3 Design parameters of the turbine: Electric power N, MW Mass flow of flash steam m sp, kg/s Mass flow of steam through condenser m k, kg/s Parameters of steam in condenser p k, kpa t k, C , , ,600 37, , ,576 6,500 37, , ,429 6,469 37, , ,285 6,475 37, , , ,380 37, , ,640 6,294 37, , ,905 6,194 36, , ,190 6,102 36, , ,295 5,986 36, , ,000 5,602 34, ,550 87,830 5,179 33, ,110 61,530 4,145 30,700 Volume flow of cooling water required through the condenser for part of the designed operating regimes of the turbine (Table 1) is determined with the following equation: q m ' ( i i ) k k k m, w = cp, w ( tw 1 tw2 ) 3,6

4 Results of cooling water flow calculation for different values of electric power output N and different values of cooling range, of the cooling tower (designed cooling range 9,2 K). N m k p k t k q v,w, m 3 /h for Δt w, K MW kg/s kpa ºC 7 K 8 K 9,2 K 11 K ,300 6, , ,429 6,469 37, ,574 6,380 37, ,640 6,294 37, ,190 6,102 36, An excerpt of microclimate conditions of Bitola, in aform of climate curve, is used in order to present the condition of air entering natural draught cooling tower during its operation in hard conditions for the months april, may, june, july, august and september, for the years 1992 to t v ϕ t vt

5 Summer climate curve for Bitola, period

6 Δt w = 7 K Δt w = 8 K Δt w = 9,2 K Δt w = 11 K t v ϕ v t vt t w1 t w2 t w1 t w2 t w1 t w2 t w1 t w2 No. C % C C C C C C C C C ,1 29,8 22,8 21,6 23,6 33,6 24,4 36,5 25, ,5 30,0 23,0 31,8 23,8 33,8 24,6 36,7 25, ,0 30,3 23,3 32,0 24,0 34,1 24,9 36,9 25, ,5 30,6 23,6 32,4 24,4 34,5 25,2 37,2 26, ,8 30,8 23,8 32,5 24,5 34,5 25,2 37,4 26, ,1 31,0 24,0 32,7 24,7 34,7 25,5 37,5 26, ,5 31,2 24,2 32,9 24,9 34,9 25,7 37,7 26, ,0 31,6 24,6 33,3 25,3 35,2 26,0 38,0 27, ,4 31,8 24,8 33,5 25,5 35,4 26,2 38,4 27, ,7 32,0 25,0 33,7 25,7 35,6 26,4 38,4 27, ,0 32,2 25,2 33,8 25,6 35,7 26,5 38,5 27, ,5 32,5 25,55 34,1 26, ,8 38,7 27, ,4 32,5 25,5 34,1 26, ,8 38,7 27, ,6 32,6 25,6 34,2 26,2 36,1 26,9 38,8 27, ,8 32,7 25,7 34,3 26,3 36,2 27,0 38,9 27, ,0 34,0 27,0 35,7 27,7 37,6 28,4 40,2 29, ,5 33,0 26,0 34,8 26,8 36,6 27,4 39,3 28, ,5 33,0 26,0 34,8 26,8 36,6 27,4 39,3 28, ,1 32,3 25,3 33,9 25,9 35,8 26,6 38,6 27,6 Calculated values of water entering and leaving the cooling tower for various ambient air parameters and cooling ranges

7 Thermal resistance of the water is the difference between the temperature of the condensate and the temperature of hot cooling water leaving the condenser: Δt kond = t k Approach to cooling range is the difference between temperature t of water leaving the cooling tower t w2 and wet bulb temperature of ambient air t vt : t = t t t Δ odd w2 w1 vt Values for thermal resistance temperature Δt kond and approach to the cooling range Δt odd,, for electrical output of N = 225 MW and N = 200 MW and optimal operating parameters of the turbine are shown in corresponding Tables. Δt kond for Δt w = t w1 t w2, K Δt odd for Δt w = t w1 t w2, K No. 7 K 8 K 9,2 K 11 K 7 K 8 K 9,2 K 11 K , , , , ,7 95 9,5 10,3 11,4 2 7,933 6,133 4,133 1,233 8,5 9,3 10,1 11,2 3 7,633 5,933 3,833 1,033 8,3 9,0 9,9 10,9 4 7,333 5,533 3,633 0,733 8,1 8,9 9,7 10,7 5 7,133 5,433 3,433 0,533 8,0 8,7 9,4 10,6 6 6,933 5,233 3,233 0,433 7,9 8,6 9,4 10,4 7 6,733 5,033 3,033 0,233 7,7 8,4 9,2 10,2 8 6,333 4,633 2,733-7,6 8,3 9,0 10,0 9 6,133 4,433 2,533-7,4 8,1 8,8 10,0 10 5,933 4,233 2,333-7,3 8,0 8,7 9,7

8 CONCLUSION From the calculations for parameters of power plant s cold end (condenser cooling tower) and values of climate curve in a period of hard operating conditions for summer months, years 1992 to 2003, the following can be concluded: For all values of wet bulb temperature t vt, the cooling tower cools the water with approach ranging from 6 to 11,4 K. Temperature of steam condensation in the condenser, in just a few cases provides real temperature of thermal resistance Δt kond, and in some cases has negative value which is impossible. This means that temperatures of steam condensation in the condenser must be higher than the designed ones. Temperatures of hot water leaving the condenser would be higher than water temperatures entering and leaving the cooling tower. Higher water temperatures at cooling tower entrance cause increased heat seizure from the water and its transfer to the air, and thus raise in enthalpy is proportional p to the increase of hot water temperature entering the cooling tower. By increasing the driving force (difference between enthalpies of water and air), heat transfer between water and air is facilitated. With higher water temperatures leaving the condenser, cooling tower is able to cool bigger volume flow of water compared to designed values; Increase of condensation temperature above the designed operating regime of the turbine causes increased specific fuel consumption in g/kwh.

9 THANK YOU FOR YOUR ATTENTION!!!

KARAKTERISTIČNE KRIVE HLAĐENJA ZA RASHLADNI TORANJ U TERMOELEKTRANI "BITOLA" - MAKEDONIJA

KARAKTERISTIČNE KRIVE HLAĐENJA ZA RASHLADNI TORANJ U TERMOELEKTRANI "BITOLA" - MAKEDONIJA TYPICAL COOLING CURVES FOR COOLING TOWER AT TPP "BITOLA" MACEDONIA V. I. Mijakovski* and I. N. Mijakovski* *Faculty