Gasification of sewage sludge and its model compounds with NTP-DBD: effect of atmosphere on product distribution and properties

doi:10.16085/j.issn.1000-6613.2021-0810

Abstract

Abstract:

The production of high-quality synthetic gas from municipal sludge turns out to be an effective solution in terms of lower environment pollution, higher added value of waste and realizing energy utilization. By using dielectric barrier discharge non-thermal plasma (NTP-DBD) technology, urban sludge and its model compounds, i.e. leucine and glucose, were gasified. The effects of different atmospheres and discharge frequencies on gas generation characteristics were studied. The solid products were subjected to Fourier infrared (FTIR), scanning electron microscope (SEM) for characterization. The results showed that the syngas concentration produced by NTP-DBD gasification sludge was increased by 1.84% compared with that of thermal gravimetric wastewater in Ar. When the discharge frequency was adjusted from 10.5kHz to 9.2kHz, the output voltage was increased by 36%, and the sludge gasification rate was increased by 5 times. When the ambient gas was CO₂, the gasification efficiency accounted for 74.86% of the volatile content of the sludge. Leucine gasification produced more H₂, CO, CO₂ and CH₄, indicating that the protein in the sludge contributes more to the gas products of sludge gasification. Compared with the performance of ordinary pyrolysis, the NTP gasification technology can not only effectively increase syngas capacity, but also ease high temperature operation and avoid the formation of highly toxic substances such as dioxins during sludge gasification.

Key words: sewage sludge, non-thermal plasma, model compound, gasification, waste treatment, pyrolysis

摘要：

城市污泥制备高品质合成燃气，是减小环境污染、提高废弃物附加值、实现能源化利用的有效方法之一。本文采用介质阻挡放电低温等离子体（NTP-DBD）技术，利用热重-质谱联用（GT-MS）对城市污泥及其模型化合物亮氨酸、葡萄糖的气化特性进行了研究。重点考察了反应气氛、放电频率对合成气体分布情况的影响，并利用傅里叶变换红外光谱（FTIR）、扫描电镜（SEM）对固体产物结构进行了表征。结果表明，在Ar气氛下，较热重热解污泥，NTP-DBD气化污泥产生合成气的浓度提升了1.84%。放电频率由10.5kHz调至9.2kHz时，输出电压提高了36%，并且污泥气化效率提高了5倍；当工作气氛为CO₂时，气化效率占污泥挥发分含量的74.86%。相较于葡萄糖而言，模型化合物亮氨酸气化产生的H₂、CO、CO₂、CH₄较多，说明污泥中蛋白质对污泥气化的气体产物贡献较大。与传统热解气化结果相比，NTP-DBD气化技术能够有效提高合成气产量、降低高温操作难度且避免污泥气化过程中二英等剧毒类物质产生。

关键词: 污泥, 低温等离子体, 模型化合物, 气化, 废物处理, 热解

CLC Number:

X705

WANG Siyi, LI Yuehui, GE Yujie, WANG Huanran, ZHAO Lulu, LI Xianchun. Gasification of sewage sludge and its model compounds with NTP-DBD: effect of atmosphere on product distribution and properties[J]. Chemical Industry and Engineering Progress, 2022, 41(4): 2150-2160.

王思怡, 李月慧, 葛玉洁, 王焕然, 赵璐璐, 李先春. NTP-DBD气化城市污泥及其模型化合物：气氛对产物分布及特性的影响[J]. 化工进展, 2022, 41(4): 2150-2160.

Figures/Tables 17

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工业分析（质量分数）/%				元素分析（质量分数）/%
V_d	FC_d	A_d		C_d	H_d	O_d^①	N_d	S_d
38.38	3.65	57.97		17.03	3.08	16.83	2.90	2.19

工业分析（质量分数）/%				元素分析（质量分数）/%
V_d	FC_d	A_d		C_d	H_d	O_d^①	N_d	S_d
38.38	3.65	57.97		17.03	3.08	16.83	2.90	2.19

气氛	放电频率 /kHz	放电功率P/W	能量密度SED /J·L^-1	输出电压 /kV	气化率 /%	最高温度 /℃
Ar	10.5	6.09	9128.38	16.2	3.75	92
Ar	9.2	9.25	13881.25	22.0	18.77	160
N₂	10.5	12.33	18489.99	24.0	22.79	217
CO₂	10.5	13.06	20406.43	24.4	28.73	228

气氛	放电频率 /kHz	放电功率P/W	能量密度SED /J·L^-1	输出电压 /kV	气化率 /%	最高温度 /℃
Ar	10.5	6.09	9128.38	16.2	3.75	92
Ar	9.2	9.25	13881.25	22.0	18.77	160
N₂	10.5	12.33	18489.99	24.0	22.79	217
CO₂	10.5	13.06	20406.43	24.4	28.73	228

气氛	放电频率 /kHz	放电功率P /W	能量密度SED /J·L^-1	输出电压 /kV	最高温度 /℃
Ar	10.5	6.77/5.95	10149/11919	16.0/16.8	136/137
Ar	9.2	12.28/11.27	18430/16912	22.4/22.8	167/181
N₂	10.5	15.89/13.78	23841/20676	24.8/24.4	199/206
CO₂	10.5	16.04/15.88	24060/23816	25.6/25.6	218/213