零能耗热源褐煤干燥及伴热利用系统热经济性分析

Thermal economy analysis of system of lignite drying with heat source of zero energy consumption and waste heat utilization

褐煤干燥对提高褐煤市场竞争力、降低发电成本具有重要作用。针对传统干燥入炉褐煤技术的干燥热源能耗高、干燥伴生余热难以利用等问题,文章提出了一种基于过热蒸汽干燥技术和锅炉余热利用的零能耗热源褐煤干燥及伴热利用系统,利用EBSILON软件建立220 MW发电机组模型,并分析了系统热平衡和电厂热经济性。结果表明:回收烟气余热、排污余热、炉渣余热占比分别为74.45%、19.78%、5.77%时,系统可以将入炉褐煤总水分由35.0%降至28.5%,而脱水量为27.16 t/h;锅炉、热源介质、伴热发电和伴热供暖的节能量分别占总节能量的58.58%、3.72%、11.36%和26.34%;利用此系统可降低总标准发电煤耗9.04 g/kWh,其年节约标煤为10222 t。

Lignite drying is of great significance to improve the market competitiveness of lignite and reduce its power generation cost.The traditional technology of drying lignite in a furnace has the problems of high energy consumption of drying heat source and difficult waste heat utilization.This paper presents a system of lignite drying with heat source of zero energy consumption and waste heat utilization based on superheated steam drying technology and boiler waste heat utilization,sets up a model of 220 MW generator by using the EBSILON software,and analyzes the system heat balance and power plant thermal economy.The results show that when the proportion of waste heat from flue gas recovery,waste heat from sewage discharge and waste heat from slag is 74.45%,19.78%and 5.77%respectively,the total water content of lignite in the furnace can be reduced from 35%to 28.5%by the system,and the dehydration rate is 27.16 t/h.Energy savings of boiler,heat source medium,power generation of waste heat and heating with waste heat account for 58%,3.72%,11.36%and 26.34%of the total energy savings respectively.By using this system,the total standard coal consumption of power generation can be reduced by 9.04 g/kWh,and the annual standard coal saving is 10222 t.