Ation And Thermal Economy Analysis Of1O00MW Ultra-supercritical Unit With Double Reheat

With the aggravation of the energy crisis, increasingly prominent of the environment issue, large-capacity, high-parameter, high-efficiency and low-emission have gradually become the main stream of thermal power equipment, and the double reheat unit is a feasible developing direction of ultra-supercritical unit. Simulating the thermal system of double reheat unit and analyzing its thermal economic are of important significance to development of double reheat unit. Based on modeling of1000MW double reheat ultra-supercritical unit under typical conditions, this paper focuses on the research of the thermal economic of double reheat direct steam extraction system and auxiliary steam extraction system. The specific research includes:The thermal system of1000MW single reheat ultra-supercritical unit is simulated, and the accuracy of the model is validated. Based on this model, the thermal system of1000MW double reheat ultra-supercritical unit are modeled, and the main parameters are designed. Then the auxiliary steam extraction system is introduced and its characteristic is analyzed. Also point out that the auxiliary pumping system can not always effectively improve the thermal economy of double reheat system.Then, based on the simulation and calculation of double reheat system in typical conditions, the distributions of main steam-water mass flow and thermal economy indices are studied. The analysis shows that, the thermal economy of double reheat unit is superior to the single reheat unit with same capacity. And the thermal economy of auxiliary steam extraction system is further improved compared with the double reheat direct steam extraction system.After that, the sensitivity of main parameters are studied, the effect of main parameters on standard coal consumption rate of double reheat unit are discussed. The results show that, for double reheat system, main steam temperature has higher effect on standard coal consumption rate than that of reheat steam temperature. Under the same load, the effects of main steam parameters on standard coal consumption rate of direct steam extraction system and auxiliary steam extraction system are basically the same.Finally, exergy analysis of the double reheat systems is conducted under the conditions of different loads, heaters removal and different ambient temperatures. The value change of exergy indicators of main equipment unit between the double reheat direct steam extraction system and auxiliary steam extraction system are compared. Economy evaluation of different types of units is also performed. According to the economy evaluation, compared with the single reheat unit, the generation cost of double reheat direct steam extraction unit decreased by0.21%, and the generation cost of auxiliary steam extraction unit decreased by0.46%。Based on the simulation of double reheat system, the double reheat unit is studied in terms of consumption analysis, exergy analysis and economy evaluation. The conclusions in this paper can provide helpful suggestions to the engineering practice.