重型燃气轮机联合循环机组三压再热余热锅炉动态建模及运行规律研究

Dynamic modeling and operating rules of three-pressure reheat waste heat recovery steam generator in heavy-duty gas turbine combined cycle unit

针对燃气轮机联合循环机组三压再热余热锅炉的动态运行特性,使用Modelica开源编程语言搭建了余热锅炉仿真模型,并与电厂实际调峰过程运行数据及Thermoflow商业软件仿真结果进行对比和验证。在实际运行工况下,从满负荷降至低负荷后稳态运行、再从低负荷升至满负荷、机组停机和边界参数扰动的动态过程中,所建模型均能较为准确地预测余热锅炉主要参数的动态响应规律。随着机组负荷从320 MW降低至280 MW,汽轮机功率从124.0 MW降至111.5 MW;高压主蒸汽流量从70.12 kg/s减至63.62 kg/s;高压主蒸汽压力从8250 k Pa降至7612 k Pa;余热锅炉入口烟气参数在约300 s的时间内随机组负荷变化,但是余热锅炉蒸汽参数需要约600s完成动态响应达到低负荷下的稳态,说明余热锅炉蒸汽参数相对于燃气轮机排烟参数随时间变化有一定滞后。在机组停机的动态过程中,汽轮机功率从130.4MW下降到5.4MW,余热锅炉高压主蒸汽温度从600.1℃降低到224.5℃,高压主蒸汽流量从76.1 kg/s减小到15.3 kg/s。

Against the dynamic operation characteristics of three-pressure reheat waste heat recovery steam generator(HRSG)of gas turbine combined cycle(GTCC)unit,the Modelica open-source programming language is used to build the simulation model for the HRSG,and the simulation results are compared with the actual operation data during peak load regulation process of the power plant.Under actual operating conditions,the established model can accurately predict the dynamic response laws of main parameters of the HRSG in the dynamic process of steady-state operation after the load drops from full load to low load,then increases from low load to full load,as well as unit shutdown and boundary parameter disturbance.When the unit load decreases from 320 MW to 280 MW,the power of the steam turbine decreases from 124.0 MW to 111.5 MW.The high pressure main steam flow rate decreases from 70.12 kg/s to 63.62 kg/s,and the high pressure main steam pressure decreases from 8250 kPa to 7612 kPa.The flue gas parameters at inlet of the HRSG change in about 300 s with the decrease of the unit load,while the steam parameters of the HRSG need about 600 s to complete dynamic response and reach steady state at low load,indicating there is a certain lag in steam parameters of the HRSG compared to the change of gas turbine exhaust gas parameters over time.In the dynamic process the unit shut down,the power of the steam turbine decreases from 130.4 MW to 5.4 MW,the high pressure main steam temperature of the HRSG decreases from 600.1℃to 224.5℃,and the high pressure main steam flow rate reduces from 76.1 kg/s to 15.3 kg/s.