Combustion characteristics and ash melting behavior of Zhundong coal/municipal sludge blended combustion

doi:10.16085/j.issn.1000-6613.2022-1494

Abstract

Abstract:

Liquid slag discharge is an important means to solve the problem of slagging and fouling in the combustion process of Zhundong coal. Blending low melting point fuel can effectively reduce the ash melting point of the mixed fuel, thereby improving the efficiency of liquid slag discharge. In this paper, high activated sludge and Zhundong coal were blended. The combustion characteristics and ash fusion behavior of the blends were studied by thermogravimetric analysis, ash melting point analysis, Fourier transform infrared spectroscopy and ash composition analysis. The results showed that the ignition temperature decreased significantly with the increase of sludge blending ratio, and the ignition performance and burnout performance of the mixture deteriorated rapidly when the sludge mass ratio exceeded 20%. The burnout temperature decreased first and then increased with the increase of sludge mixing ratio, and reached the lowest when the sludge mixing mass ratio was 10%. The results of infrared spectroscopy showed that the incorporation of sludge promoted the pyrolysis and combustion of active hydroxyl groups, aliphatic functional groups, oxygen-containing functional groups and aromatic functional groups in pulverized coal. The Fe₂O₃ in the sludge reacted with SiO₂ in the coal to form a low melting point eutectic, which made the mixed fuel be of a relatively low ash melting temperature. When the sludge blending ratio was 10%, the ash melting temperature of the mixture was 1080°C. Considering the stability of fuel combustion and the reduction of ash melting point, it was recommended that the optimal blending ratio of sludge and Zhundong coal is 1∶9.

Key words: blend, coal combustion, municipal sludge, ash-melting characteristics, waste treatment

摘要：

液态排渣是解决准东煤燃烧过程中结渣沾污问题的重要手段，而掺烧低熔点燃料可以有效降低混合燃料的灰熔点，进而提高液态排渣效率。本文将高活性污泥与准东煤进行掺混，综合利用热重分析仪、灰熔点分析、傅里叶红外光谱分析和灰成分分析方法，对混合物的燃烧特性及灰熔融行为进行研究。结果表明：随着污泥掺混比例的增加，着火温度显著降低，且混合物在污泥质量占比超过20%时综合燃烧指数显著降低；燃尽温度则随污泥混合比的增加呈现出先降低后升高的趋势，且在污泥掺混质量分数为10%时达到最低。红外光谱测试结果表明，污泥的掺入促进了煤粉中羟基、脂肪族官能团、含氧官能团及芳香族官能团等官能团的热解燃烧。污泥中的Fe₂O₃与煤中SiO₂反应生成了低熔点共熔物，使得混合燃料具有相对较低的灰熔融温度，当污泥掺混比为10%时，混合物的灰熔融温度为1080℃。综合考虑燃料燃烧稳定性和降低灰熔点，推荐污泥与准东煤的最佳掺烧比例为1∶9。

关键词: 混合, 煤燃烧, 市政污泥, 灰熔融特性, 废物利用

CLC Number:

TQ534

XIU Haoran, WANG Yungang, BAI Yanyuan, ZOU Li, LIU Yang. Combustion characteristics and ash melting behavior of Zhundong coal/municipal sludge blended combustion[J]. Chemical Industry and Engineering Progress, 2023, 42(6): 3242-3252.

修浩然, 王云刚, 白彦渊, 邹立, 刘阳. 准东煤/市政污泥混燃燃烧特性及灰熔融行为分析[J]. 化工进展, 2023, 42(6): 3242-3252.

Figures/Tables 13

References 20

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项目	MS	PC
工业分析^①/%
M	3.64	3.82
V	22.12	37.22
FC	6.01	44.53
A	68.23	8.02
V/FC	5.27	0.85
元素分析^②/%
C	9.11	50.20
H	1.75	2.80
N	1.83	0.56
O	11.35	9.95
S	0.55	0.60
C/H	5.21	17.93
低热值/MJ·kg^-1	4.95	18.29

项目	MS	PC
工业分析^①/%
M	3.64	3.82
V	22.12	37.22
FC	6.01	44.53
A	68.23	8.02
V/FC	5.27	0.85
元素分析^②/%
C	9.11	50.20
H	1.75	2.80
N	1.83	0.56
O	11.35	9.95
S	0.55	0.60
C/H	5.21	17.93
低热值/MJ·kg^-1	4.95	18.29

样品	DTG_max/%·min^-1	DTG_mean/%·min^-1	T_max/°C	t_max/min	t_i/min	t_b/min	Δt_1/2/min
PC	9.78	5.29	447.41	41.75	35.57	49.80	38.73
PC90MS10	8.93	4.54	452.47	42.26	33.73	49.87	38.71
PC80MS20	8.27	3.84	453.51	42.27	33.57	50.21	39.52
PC70MS30	7.65	3.61	455.13	42.52	33.29	49.96	39.62
PC60MS40	5.93	1.94	455.72	42.58	29.44	50.35	39.39
MS	1.77	0.73	458.35	42.85	18.03	55.90	37.82

样品	DTG_max/%·min^-1	DTG_mean/%·min^-1	T_max/°C	t_max/min	t_i/min	t_b/min	Δt_1/2/min
PC	9.78	5.29	447.41	41.75	35.57	49.80	38.73
PC90MS10	8.93	4.54	452.47	42.26	33.73	49.87	38.71
PC80MS20	8.27	3.84	453.51	42.27	33.57	50.21	39.52
PC70MS30	7.65	3.61	455.13	42.52	33.29	49.96	39.62
PC60MS40	5.93	1.94	455.72	42.58	29.44	50.35	39.39
MS	1.77	0.73	458.35	42.85	18.03	55.90	37.82

样品	T_i/°C	C_i×10²/%·min^-3	T_b/°C	C_b×10³/%·min^-4	S×10⁷/%²·°C^-3·min^-2
PC	85.61	0.66	26.81	0.12	6.60
PC90MS10	67.17	0.63	25.77	0.11	5.72
PC80MS20	65.59	0.58	531.30	0.10	4.47
PC70MS30	62.87	0.54	529.41	0.09	3.96
PC60MS40	24.30	0.47	533.42	0.07	2.05
MS	10.30	0.23	588.92	0.02	0.50