燃煤烟气砷污染控制技术研究进展

Review on arsenic pollution control technologies in coal-fired flue gas

砷是煤中常见的痕量有毒元素,燃煤电厂现有污染控制设备虽可脱除烟气中部分砷化合物,但由于燃煤量巨大,由燃煤排放的总砷量仍是最主要的人为大气砷排放源.为了有效控制燃煤过程砷的污染排放,特别是烟气砷的排放,国内外学者进行了大量研究.本文综述了近年来燃煤烟气砷污染控制技术的相关研究进展,分为燃烧前、燃烧中与燃烧后进行论述.燃烧前控制技术主要对煤进行物理与化学等预处理实现砷脱除;燃烧中通过混煤燃烧与加入添加剂方式使细颗粒物中的砷向粗颗粒物转化,并与飞灰、底灰一同脱除;燃烧后利用吸附剂将砷化合物固化从而被污染控制设备捕集.相比之下,燃烧后控制技术研究最为广泛.各项技术虽可取得较好的砷脱除效果,但实际应用和作用机理还需进一步探索.

Arsenic is one of the common hazardous trace elements in coal.Although the emitted arsenic can be partly removed by the existing air pollution control devices in coal-fired power plants,the total amount of arsenic emitted by coal burning is huge and coal combustion is still regarded as the most important anthropogenic emission source of atmospheric arsenic.In order to effectively control arsenic emission from coal burning process,especially from flue gas,many studies about arsenic capture and control in flue gas had been carried out.This review summarized the related studies about arsenic pollution control in coal-fired flue gas in recent years,and the techniques were divided into pre-combustion removal techniques,during combustion removal techniques and postcombustion removal techniques.The pre-combustion control techniques are mainly conducted via physical and chemical pretreatment to remove arsenic.The during combustion removal techniques can agglomerate fine particles into coarse particles for easy removal of arsenic by coal blending and chemical additives adding technique.The post-combustion removal techniques capture and immobilize arsenic by adsorbents,and then the captured arsenic will be removed by air pollution control devices.The post-combustion control techniques are the most widely studied strategy among them.Although these technologies achieve considerable arsenic removal efficiency,the further investigations about practical applications and mechanisms are still required in the future.