超超临界1000 MW机组零号高压加热器宽负荷回热技术

Wide-load regenerative technology of No.0 high-pressure heater in an ultra supercritical 1 000 MW unit

本文以某发电公司超超临界1 000 MW机组为例,重点研究零号高压加热器(高加)的布置形式和控制策略及其对锅炉给水温度、机组热耗、脱硝系统投入率等方面的影响。结果表明:在保证低负荷时省煤器出口给水欠焓的前提下,通过对零段抽汽调节阀后蒸汽压力的合理控制,投运零号高加可提高机组中低负荷段的锅炉给水温度,使中低负荷段给水温度稳定在290℃;提高中低负荷段选择性催化还原(SCR)脱硝系统入口烟温,使其保持在催化剂高效反应区间,提高脱硝系统投运率,具有较好的环保效果;同时选择合理的零段抽汽参数可降低中高负荷段机组热耗,具有一定的节能效果。该结论对同类型新建机组零号高加的投运、商业运行,以及机组增设零号高加的改造工作具有指导和借鉴作用。

In this study, an ultra-supercritical 1 000 MW unit of a power generation company is taken as an example to study the layout, control strategy of No.0 high-pressure heater and its influence on the temperature of boiler feed water, heat consumption and the running rate of selective catalyst reduction（SCR） denitration system. The results show that, in the premise of guaranteeing feed water owes enthalpy at the export of economizer under low-load, with the proper control of steam pressure behind the No.0 extraction control valve, the application of the No.0 highpressure heater can increase the temperature of boiler feed water under medium and low loads and stabilize the temperature of boiler feed water at 290 ℃ under medium and high loads. The inlet flue gas temperature at SCR system under medium and low loads can also be increased and kept at the efficient reaction temperature range of the catalyst, which can improve the running rate of the denitration system and have good environmental protection value. Meanwhile, the reasonable No.0 extraction steam parameters could reduce the unit heat consumption under medium and high loads, which has great energy-saving value. This conclusion is of guidance and reference for the application, commercial operation, addition and retrofit of the No.0 high-pressure heater of the same type new units.