1000MW超超临界二次再热机组运行参数优化研究

发布时间：2018-07-24 12:48

【摘要】：现有的火力发电技术面对着社会、资源和经济等多方面的压力,进一步研究和发展更加环保低耗的火力发电技术是解决以后火电发展问题的最佳选择。面对我国社会和科技的飞速发展,各个行业的电力需求和环保的压力对我国节能减排有了更高的标准。更深层次地研究和优化机组的各项运行参数,对实现机组降低平均煤耗率具有重要意义。现代大型火电机组运行较为复杂,以某N1000-32.1/600/620/620机组为例进行研究。基于汽轮机、凝汽器、循环水系统及给水系统的变工况算法分别以机组热耗率最小、机组功率变化量与循环水泵耗功之差最大及全厂供电效率最高为目标函数,建立了主蒸汽压力、排汽压力及以供电效率最高为优化目标函数的运行参数优化模型,以确定机组的最优运行参数。计算结果表明:在主蒸汽压力优化中,机组配置的调节阀个数较少,调节阀门产生的节流损失对机组的热耗率影响较大。通过比较一阀全开一阀节流、两阀滑压节流配汽和纯滑压运行三种配汽方式下机组热耗率的变化可知,在满足机组负荷条件下,一阀全开一阀节流配汽优于纯滑压运行和两阀滑压节流配汽。机组在同一负荷下的最优值略大于设计值,同时优化热耗率也比设计值略低。在变工况运行区域内,通过主蒸汽压力的改变使机组的热经济性达到最好,从而获得机组实际运行的最优主蒸汽压力曲线。在排汽压力和循环水泵运行参数优化中,在某一给定循环水温度下,当机组功率升高时,最优循环水泵流量和最优排汽压力均有所升高;在机组某一给定负荷下,当循环水温度低于10℃或高于20℃时,冷却水温度对排汽压力的影响较为明显,且机组功率增量变化较大。当循环水温度为30℃时,为尽量降低凝汽器压力,循环水泵流量基本达到最大值8866kg/s。在以供电效率最大为目标函数的运行参数优化中,在给定某一机组功率的前提下,随着循环冷却水温度的升高,最优主蒸汽压力、排汽压力、循环水流量都有所升高,且由于电动循环水泵和汽动给水泵的耗功增加,使全厂的供电效率降低。以85%负荷为例,当循环水温度从5℃上升到30℃时,供电效率依次为45.26%、45.13%、45.08%、45.03%、44.95%、44.89%,其中最高值与最低值相差为0.37%。因此机组在运行时要尽量降低循环水温度,保证获得较好的热经济性。
[Abstract]:The existing thermal power generation technology is facing social, resource and economic pressures. Further research and development of more environmentally friendly and low-consumption thermal power generation technology is the best choice to solve the problem of thermal power development in the future. Facing the rapid development of our society and science and technology, the demand for electricity and the pressure of environmental protection in various industries have a higher standard for energy saving and emission reduction in China. It is of great significance to study and optimize the operation parameters of the unit in a deeper level to reduce the average coal consumption rate of the unit. The operation of modern large thermal power generating units is more complicated, taking a N1000-32.1 / 600 / 620 / 620 unit as an example. Based on the variable working condition algorithms of steam turbine, condenser, circulating water system and feed water system, respectively, the minimum heat consumption rate of the unit, the biggest difference between the unit power change and the power consumption of the circulating water pump and the highest power supply efficiency of the whole plant are the objective functions. The optimization models of main steam pressure, exhaust steam pressure and operation parameters with the maximum power supply efficiency as the optimization objective function are established to determine the optimal operating parameters of the unit. The results show that in the optimization of the main steam pressure, the number of regulating valves is small, and the throttling loss caused by the regulating valves has a great influence on the heat consumption rate of the units. By comparing the change of heat consumption rate of the unit under three steam distribution modes of one valve, two valve sliding pressure throttling and pure sliding pressure operation, it can be seen that the heat consumption of the unit can be satisfied under the condition of unit load. The throttling distribution of one valve is superior to that of pure sliding pressure operation and two valve sliding pressure throttling steam distribution. The optimum value of the unit under the same load is slightly larger than the design value, and the optimized heat consumption rate is also slightly lower than the design value. The thermal economy of the unit is best through the change of the main steam pressure in the operation area of the variable working condition, and the optimal main steam pressure curve of the unit is obtained. In the optimization of exhaust steam pressure and circulating pump operating parameters, under a given circulating water temperature, the optimal circulating pump flow rate and optimal exhaust steam pressure are increased when the unit power is increased, and at a given load of the unit, the optimal circulating pump flow rate and the optimal exhaust steam pressure are increased. When the circulating water temperature is lower than 10 鈩，

本文编号：2141434