| This essay introduces the theory of equivalent entropy drop method,gives out a general equation of the equivalent entropy drop method in the reheat units and builds a thermodynamic model for efficiency analysis of the ultra supercritical units.Based on the given thermodynamic model and parameters in A Power Plant,the influence to the coal consumption when main parameters changing is conducted,which includes the temperature and pressure of the main steam,the temperature of the reheat steam,the vacuum of the condenser and the cooling water quantity of the reheat system.In consideration of the drain heater in the LP heater system in A Power Plant,some modification is made to the traditional equivalent entropy drop method equation.The equivalent entropy drop and extraction efficiency are calculated using the revised equation under 100% THA and 75% THA.Different factors to the coal consumption are calculated as well,including terminal heat temperature difference,extraction pressure loss,dissipating heat of HP heaters and whether the HP heater system runs or not.Based on the performance curve given by the turbine manufacturer,condenser vacuum is calculated applying to different circulation water temperature and quantity.Using the equivalent entropy drop method,the curve of the condenser vacuum to heat consumption is plotted out.Polynomial fitting is run through some mathematics software and the polynomial is then used to guide the working of circulation system.After applying the strategy,the heat consumption is effectively reduced which is verified by on the SIS system.A strategy of how the condensed water system is involved in the primary frequency modulation is introduced.It lowers the pressure set point in order to open the controlling valve,thus reducing the throttling loss.The speed responding to AGC and the primary frequency modulation is guaranteed by applying the method.Based on the equivalent entropy drop method,the influence of the condensed water to the power capability is calculated,and the result is concluded.A brief introduction is made to the WGGH system of A Power Plant,and the energy saving effect is computed on the gas heat recycled by the condensed water.And the optimized shunt coefficient of the condensed water is proposed.The parameters of heat provision and the energy saving effect are calculated under the 100% THA and75% THA. |
