Department of Chemical Engineering, Industrial Chemistry and Material Science, University of Pisa, Largo Lucio Lazzarino 1, 56126 Pisa, Italy.
Waste Manag. 2012 Oct;32(10):1826-34. doi: 10.1016/j.wasman.2012.04.018. Epub 2012 May 31.
In the present work, the gasification with air of dehydrated sewage sludge (SS) with 20 wt.% moisture mixed with conventional woody biomass was investigated using a pilot fixed-bed updraft gasifier. Attention was focused on the effect of the SS content on the gasification performance and on the environmental impact of the process. The results showed that it is possible to co-gasify SS with wood pellets (WPs) in updraft fixed-bed gasification installations. However, at high content of sewage sludge the gasification process can become instable because of the very high ash content and low ash fusion temperatures of SS. At an equivalent ratio of 0.25, compared with wood pellets gasification, the addition of sewage sludge led to a reduction of gas yield in favor of an increase of condensate production with consequent cold gas efficiency decrease. Low concentrations of dioxins/furans and PAHs were measured in the gas produced by SS gasification, well below the limiting values for the exhaust gaseous emissions. NH(3), HCl and HF contents were very low because most of these compounds were retained in the wet scrubber systems. On the other hand, high H(2)S levels were measured due to high sulfur content of SS. Heavy metals supplied with the feedstocks were mostly retained in gasification solid residues. The leachability tests performed according to European regulations showed that metals leachability was within the limits for landfilling inert residues. On the other hand, sulfate and chloride releases were found to comply with the limits for non-hazardous residues.
在本工作中，使用中试固定床上行式气化炉研究了 20wt.%水分的脱水污水污泥（SS）与常规木质生物质的空气气化。重点关注 SS 含量对气化性能和过程环境影响的影响。结果表明，SS 可以与木屑颗粒（WPs）在上行固定床气化装置中共气化。然而，由于 SS 的高灰分含量和低灰熔点，在高 SS 含量下，气化过程可能变得不稳定。在当量比为 0.25 的情况下，与木屑颗粒气化相比，添加 SS 导致气体产率降低，有利于冷凝液产量增加，从而导致冷煤气效率降低。通过 SS 气化产生的气体中测量到的二恶英/呋喃和多环芳烃浓度很低，远低于废气排放限值。由于大多数这些化合物被保留在湿式洗涤器系统中，因此 NH(3)、HCl 和 HF 的含量非常低。由于 SS 中的硫含量高，因此测量到高 H(2)S 水平。进料中提供的重金属主要保留在气化固体残渣中。根据欧洲法规进行的浸出试验表明，金属浸出率符合填埋惰性残渣的限值。另一方面，发现硫酸盐和氯化物的释放符合无危险残渣的限值。
