新型燃煤电站低温烟气余热优化利用系统  

A New Low-temperature Flue Gas Waste Heat Optimized System in Coal-fired Power Plant

作　　者：张晨旭[1] 韩宇[1] 徐钢[1] 杨勇平[1] 许诚[1] 黄圣伟[1] 

机构地区：[1]华北电力大学国家火力发电工程技术研究中心

出　　处：《电站系统工程》2014年第4期33-35,38,共4页Power System Engineering

基　　金：国家重点基础研究发展计划项目(973计划)(2011CB710706);国家自然科学基金项目(U1261210);北京高等学校青年英才计划项目(71A1411127)资助

摘　　要：锅炉尾部排烟温度一般在120～140℃，其热损失可达锅炉输入总热量的3％～8％，因此对锅炉尾部排烟余热进行回收意义重大。在对常规余热利用系统换热特性进行深入分析的基础上，提出一种新型低温烟气余热优化利用系统，该系统利用机炉两侧低品位热能预热入炉空气，提高空气预热器入口风温的同时，减少了空气预热器中烟气一空气换热量，并将置换出的这部分热能引入回热系统加热给水和高温凝结水，节约部分高级抽汽，进而增加机组出功。以某典型1000Mw燃煤机组为例，结合热力学的相关原理深入分析了优化系统的节能特性。研究结果表明：优化方案中机组净出功较常规方案增加了20．23Mw，供电煤耗降低值则由常规方案的0．93g／kWh提高到5．09g／kWh，同时全厂ll用效率由常规方案的43．58％提高到43．92％。综合分析，系统节能改造收益显著。Generally speaking, the exhaust flue gas temperature varies in the range of 120℃ to 140℃, which causes the heat loss accounted for 3%-8% boiler total input energy. It is significant to recycle the waste heat of the exhaust flue gas. With the deeply analysis of the heat transfer characteristics in the conventional waste heat utilization system, a novel low-temperature flue gas waste heat utilization system （WHUS） is proposed. In the proposed WHUS, the air is preheated by the exhaust flue gas on the boiler side and the low-pressure steam extraction on the turbine side, also the heat transfer is decreased with the improvement of entrance air temperature in the air preheater. Thus higher grade flue gas waste heat is replaced and it can be introduced to heat the feed water and the high-temperature condensed water. Consequently, part of the high-pressure steam is saved for expansion, which obtains more net power output. It consults the actual operation data of a typical 1000MW ultra-supercritical coal-fired unit, in-depth analysis of the energy-saving characteristics of the novel WHUS using the principle of thermodynamics. Result shows that the novel WHUS has excellent performance： compared to the conventional WHUS, the net power output increases by 20.23MW, the saving of standard coal equivalent can be from the conventional scheme of 0.93 g/kWh to 5.09 g/kWh and the exergy efficiency can be from the conventional scheme of 43.58% to 43.29%.~

关 键 词：低温烟气 余热回收 综合优化 炯分析 

分 类 号：TK219[动力工程及工程热物理—动力机械及工程]