煤粉炉掺烧城市污泥积灰结渣与污染物排放特性

Characteristics of ash deposition and pollutant emission during co-firing of pulverized coal and municipal sludge

为了得到燃煤电厂掺烧城市污泥后的燃烧、结渣以及污染物排放特性,在自建一维沉降炉中,开展了5个不同掺混比例(0、5%、10%、15%、20%)下的混燃试验,并参照《火电厂大气污染物排放标准》(GB 13223—2011)等规定对不同工况下的样品、数据进行取样和测量。结果表明,随着污泥掺烧量增加,炉膛温度呈下降趋势,掺混比例达到20%时,炉膛顶部温度下降40℃左右;随着污泥掺烧比例增加,锅炉结渣倾向加重,燃烧生成的灰样主要成分为K-Al-Si和K-Ca-Si复合盐类;随着掺烧比例的提高,NOx的排放量呈现先增加后降低的趋势,SO_(2)的排放量逐渐降低;5种掺混比例下烟气中的二噁英与飞灰中的重金属含量分别满足《燃煤耦合污泥电厂大气污染物排放标准》(DB 31/1291—2021)与《农用粉煤灰中污染物控制标准》(GB 8173—87)要求;与纯燃煤相比,掺烧20%污泥时,可减少CO_(2)排放约0.34%。燃煤锅炉掺烧城市污泥可作为双碳战略下高效节能降碳的一种选择。

In order to obtain the combustion and slag characteristics of coal-fired power plants after sludge blending,as well as the pollutant emission law,pilot test studies are carried out for five working conditions(sludge blending ratio of 0,5%,10%,15%and 20%in the one-dimensional sedimentation furnace).The results show that with the increase of sludge blending amount,the furnace temperature decreases,and the temperature at the top of the furnace decreases by 40°C when the mixing ratio reaches 20%.SEM and EDS analysis of the slag particles showed that with the increase of sludge incineration ratio,the slag tendency of the boiler increased,and the main components of the ash samples generated by combustion were K-Al-Si and K-Ca-Si composite salts.With the increase of the blending ratio,the emission of NOx increased first and then decreased,and the emission of SO_(2)gradually decreased.The contents of dioxins in flue gas and heavy metals in fly ash meet the requirements of DB 31/1291-2021"Emission Standard for Air Pollutants in Coal-fired Coupled Sludge Power Plants"and GB 8173-87"Control Standard for Pollutants in Agricultural Fly Ash".Through the calculation,it is found that the sludge blending will reduce the CO_(2)emissions,and when the sludge blending ratio is 20%,the CO_(2)emissions will be reduced by about 0.34%.Sludge co-firing in coal-fired boilers can be an option for efficient energy saving and carbon reduction under the dual-carbon strategy.