温度和气氛对高K高S糠醛渣灰分的烧结特性研究

Effect of temperature and atmosphere on ash sintering characteristics of furfural residue with high K and S

糠醛渣的能源化利用是糠醛产业清洁生产和碳减排的有效途径。然而,现有的直接燃烧利用常面临着因糠醛渣高K引起的灰分烧结严重、高S导致的SO_(x)排放量大和高水含量导致的燃烧效率低等难题。基于此,在管式炉中考察了单一气氛(N_(2)、CO_(2)、O_(2))和混合气氛(N_(2)+H_(2)O、CO_(2)+H_(2)O、O_(2)+H_(2)O)中糠醛渣灰在不同温度下的烧结特性,并对灰分颜色、收缩率、微观形貌、矿物质成分和K/S释放等特性进行系统分析。灰分热收缩行为显示,随温度升高,灰样收缩率增加;在单一气氛中添加水蒸气能促进灰分烧结。SEM分析发现,在灰分烧结前,其微观结构在低温下已出现熔融和结渣。XRD分析表明,灰分烧结与低熔点矿物生成紧密相关。单一气氛中,高温下N_(2)促进钾长石生成;CO_(2)抑制钾长石生成;O_(2)促进钙铝黄长石和透辉石生成。在混合气氛中,水蒸气的出现促进多种低熔点钾铝硅酸盐生成,如钾长石和白榴石等。XRF分析显示,随温度升高,灰样中K的固留率(GK)和S的固留率(GS)降低;在考察的单一气氛中,高温时,N_(2)中G_(K)最低;GS受气氛的影响较小。在考察的复合气氛中,高温时,G_(K)受气氛影响较小;G_(S)受气氛影响严重,特别地,O_(2)+H_(2)O气氛中G_(S)最高,S逸散最少。为抑制糠醛渣灰分烧结和K/S元素逸散到气相中,糠醛渣在流化床燃烧过程中应控制运行温度(低于900℃)、降低气氛中N_(2)的含量。

The energy utilization of furfural residue is an effective way for clean generation and carbon reduction in furfural industry.However,the existing direct combustion and utilization often face problems such as serious ash sintering caused by high K of furfural slag,large SOx emissions caused by high S,and low combustion efficiency caused by high water content.To solve these problems,in this study,a tubular furnace was employed to research the sintering behavior of furfural residue ash in the pure(N_(2),CO_(2),O_(2))and mixed(N_(2)+H_(2)O,CO_(2)+H_(2)O,O_(2)+H_(2)O)atmosphere at different temperatures.The variations of ash color,shrinking rate,micromorphology,mineral compositions and K/S release characteristics were systematically analyzed.The results show that with the increase of temperature,the ash sample shrinking rate increased.Steam played important promotion roles in ash sintering.SEM analysis indicated that the ash microstructure was melted and slaged at low temperature before sintering.XRD analysis displayed that ash sintering was closely related to the composition change of ash.N_(2) promoted the composition of microcline,CO_(2) inhibited the composition of microcline,while O_(2) strengthened the formation of anorthite and diopside.Steam promoted the formation of various potassium aluminum silicates such as microcline and leucite.XRF analysis indicated that,with the increase of temperature,G_(K)(retention rate of K)and G_(S)(retention rate of S)in ash decreased.In pure atmospheres,G_(K) was the smallest in N_(2),while the effect of pure atmosphere on G_(S) was limited.In the mixed atmospheres,compared to G_(K),the effect of atmospheres on G_(S) was much more obvious,especially in O_(2)+H_(2)O.To restrain ash sintering and migrate K and S,the suitable operating conditions of furfural residue combustion in fluidized bed should be at temperature below 900℃and lower N_(2) content in atmosphere by introducing a stream of flue gas.