Thermal Economic Performance Analysis And System Optimization Of 600MW Power Unit

For further reducing the thermal power plant's generating cost, it's necessary to analyze the thermal economic performance of the thermal unit and to optimize the thermal system. The paper comparative analyses the on-line calculation models of the turbine's exhaust enthalpy which the system can't directly measure from open thermal system's energy balance and from steam-turbine unit's power balance. And the on-line calculation models from steam-turbine unit's power balance which has quick speed and high precision. At the same time, the paper analyzes the variable conditions of the unit's flow passage, the heater and the condenser. And it determines the main parameter's target value in running conditions.Based on the unit thermal economy state equation, the paper sets up the calculation models of the unit's initial and final parameters, the heater terminal temperature difference, heater steam extraction pressure loss, condenser undercooling and the auxiliary steam-water's flow what effect units'thermal economic performance. And it also deduces the conception of the heat exchange vector. The model takes the turbine power variation and the boiler heat absorption variation into the same frame which makes the calculation models of the local parameters impacting on the unit's thermal economy performance simply, apts to computer programming and are suitable for the thermal economic performance of the different thermal units. Taking a 600MW sub-critical unit as example, the paper quantificationally analyzes of the thermal unit's thermal economic performance. Under the different conditions, the calculation of the unit's initial and final parameters which have an impact on the standard coal consumption rate using of the paper's method occurs a certain deviations compared with using of the feature curve method's. The calculation of other small perturbation parameters which have an impact on the standard coal consumption rate using of the paper's method is the same as using of the equivalent enthalpy drop method's. Aiming at the problems of the unit's system, the paper optimizes the unit of the shaft seal and use of the leakages system, the superheater spray water for attemperation system, the low pressure heater drain system and the auxiliary steam system for enhancing the unit's heat economical performance. Also it supplies qualifications for enhancing units'heat economical performance and optimizing the same type units.