燃煤炉预混—喷钙二段脱硫技术研究

STUDY ON TWO-STAGE DESULFURIZATION TECHNOLOGY WITH PREMIXED AND INJECTED SORBENTS IN COAL-FIRED BOILERS

文章指出了煤燃烧高温脱硫3方面难点:①石灰石分解速率低于煤燃烧时硫析出速率;②脱硫产物在CaSO_41200℃以上再分解;③CaO颗粒高温严重烧结。对此,提出二段脱硫工艺,即一部分添加剂与煤预混进行料层脱硫,另一部分喷入炉内捕捉烟气中硫。建立了10t/h链条炉二段脱硫示范装置。试验和运行结果表明锅炉除尘器前脱硫率达到70％以上,除尘器后,烟气经半干法处理可达到80％～90％。

In general, blending calcium-based sorbents with feed coal only gives a low SO2 reduction efficiency from flue gas derived from coal combustion. The main reasons include three aspects: ① decomposition rate of limestone is lower than sulfur release rate derived from coal combustion;② sulfation product CaSO4 is thermal unstable at high temperature above 1200℃; ③ CaO particles have high level of sintering at high temperature. In order to promote the in-furnace sulfur removal effect, a demonstration two-stage desulfurization process has been installed in a 10t/h traveling-grate boiler and operated for a period, in which some sorbents are premixed with feed coal to take sulfation reactions on the grate and others are injected into the furnace to capture SO2 in the combustion gas. This process gives a SO2 reduction efficiency of about 70% in the furnace and 80-90% after the flue gas humidification in a water-film dust catcher.