催化裂化烟气排放控制技术现状及面临问题的分析

FCC Flue Gas Emission Control Technology Today and Challenges

国内催化裂化装置再生烟气SOx、NOx排放限值相关的国家政策以及国家标准、地方标准日益严格,催化裂化烟气脱NOx即将纳入强制执行规范。介绍了国内催化裂化烟气的特点、相关排放标准以及主要的污染物排放控制技术的特点和发展现状。当催化原料油硫含量在0.12%～0.50%时,宜采用脱SOx助剂技术;在0.25%～1.50%时,宜采用洗涤脱SOx技术;在0.75%～3.00%时,宜采用回收法脱SOx技术。SCR工艺被证明是应用最多且NOx脱除效率最高、最为成熟的脱NOx技术。分析了主流脱SOx、脱NOx技术的工程方面问题:钠碱洗涤法脱SOx技术面临消耗碱和含盐污水排放的问题;钠钙双碱法脱SOx技术则面临脱硫石膏质量和CO2排放的问题;臭氧氧化法(LoTOxTM)脱NOx技术面临电耗量大和臭氧成本高的问题;海水洗涤法受地域制约且不能处理高含硫烟气;使用脱SOx、脱NOx助剂也有一定局限性。展望了资源化烟气脱SOx、选择性催化还原脱NOx、一体化催化烟气脱除有害污染物的应用前景。

China's national policies and national and local standards relating to the emission of SOx and NOx in FCC flue gas have been increasingly strict.Removal of NOx from FCC flue gas emitted will soon become a compulsory requirement.This article describes the characteristics of FCC flue gas,relevant emission standards and the characteristics and current status of main pollutant emission control technologies in China.When the content of sulfur in the catalytic feed is between 0.12% and 0.50%,SOx-removing additives are more suitable;when the sulfur content ranges between 0.25% and 1.50%,SOx-removing washing technology is more suitable;and when the sulfur content is between 0.75% and 3.00%,recycling SOx-removing technology is better suited.SCR has proved to be the most used,most efficient and most mature NOx-removing technology currently available in the marketplace.The article analyzes the engineering problems with mainstream SOx and NOx removing technologies: Soda washing SOx-removing technology has soda consumption and salt-containing sewage discharge problems;the Na-Ca double alkali method SOx-removing technology has desulfurized gypsum quality and CO2 emission problems;the LoTOxTM NOx-removing technology has power consumption and ozone cost problems;the seawater washing method has geographical constraints and is unable to treat high-sulfur flue gas;and SOx and NOx removing additives also have their limitations.The article also looks at the prospect for the application of flue gas SOx recycling technology,selective catalytic reduction NOx removing technology and technology for integrated removal of pollutants in catalytic flue gas.