焦化烟气活性焦低温脱硝工艺与反应器设计

Process and reactor design of low temperature coking flue gas denitration with activated coke

为了开发适用于焦化烟气的干法脱硫低温脱硝技术,在现有活性焦脱硫脱硝技术的基础上,针对焦化烟气低硫高硝、排烟温度低、湿度高等特点,选取一种商用活性焦,在试验装置上分别研究了空速、温度、氨氮比和湿度等对活性焦脱硝性能的影响,在此基础上设计了左右并联式、错流移动床反应器结构形式,并根据理论计算和结构设计模型完成反应器图纸设计,建成60万t/a焦炉配套的活性焦干法脱硫低温脱硝工业装置,并在工业装置上开展了72h工业性试验,验证实验室工艺与反应器设计可行性。结果表明,活性焦脱硝适宜的工艺参数条件为:空速300h-1,反应温度140℃,氨氮比1.3,烟气湿度不宜超过16%;以某焦化厂烟气为例,进行了反应器尺寸理论计算,设计出15万Nm^3/h烟气量处理能力的反应器尺寸为8m×33m×4m;工业性试验的烟气温度、氨氮比、湿度均以实验室结果为基准开展试验,烟气平均进口温度约135℃、氨氮比1~1.1∶1、烟气平均湿度12.5%,在此条件下,装置脱硫、脱硝效率分别为99%和89%,在基准氧含量为8%时,SO2和NOx平均排放浓度分别为4mg/m^3和92mg/m^3,满足焦化烟气超低排放指标要求。

In order to develop dry desulfurization and low-temperature denitrification technology for coking flue gas,based on the characteristics of coking flue gas,such as low sulfur and high nitrate,low temperature and high humidity of flue gas,etc.,effects of air speed,temperature,ammonia nitrogen ratio and humidity on the denitrification performance of commercial active coke are studied.The reactor structure is designed,and reactor size is calculated by calculation model.According to the theoretical calculation and structural design model,the reactor drawing is completed,and activated coke dry desulfurization and low temperature denitrification industrial device matching 600 thousand tons per year coke oven is built.72 h industrial test is carried out on the industrial device to verify the feasibility of the laboratory process and reactor design.The results show that the suitable process parameters for denitrification of activated coke is as follows:space velocity 300 h-1,reaction temperature140℃,ammonia nitrogen ratio 1.3,flue gas humidity no more than 16%.Aiming at improving desulfurization and denitrification efficiency of activated coke reactor,the structure of reactor is left-right parallel and cross flow moving bed reactor.Flue gas from a coking plant is taken as an example,and a 150000 Nm^3/h activated coke desulfurization and denitration reactor is designed with a size of 8 m×33 m×4 m.The flue gas temperature,ammonia nitrogen ratio and humidity in the industrial test are based on the laboratory results with the average flue gas inlet temperature about 135℃,ammonia nitrogen ratio 1~1.1∶1,and the average flue gas humidity 12.5%,and the desulfurization and denitrification efficiency of the device are 99%and 89%,respectively.When the reference oxygen content is 8%,the average emission concentration of SO2 and NOxare 4 mg/m^3 and 92 mg/m^3,respectively,which meet the ultra-low coking flue gas emission index requirements.