Slagging characteristics of co-firing process of sludge and solid waste as basic fuels

doi:10.16085/j.issn.1000-6613.2024-2062

Abstract

Abstract:

In recent years, sewage sludge and high-calorific-value industrial organic solid wastes have been widely utilized as recovered fuels for co-incineration in power generation, enhancing the synergistic benefits of energy recovery and solid waste disposal. This study conducted an in-depth analysis of the slagging characteristics associated with the co-combustion of these two major types of solid waste. Four representative types of industrial solid waste and municipal sludge were selected as research subjects, with coal used as an auxiliary fuel. The investigation primarily focused on the microstructural features of the resulting ash, mineral phase formations, slagging characteristic indices, and the slagging behavior observed in ash samples from large-scale incineration plants co-firing sludge and industrial waste as substitutes for coal. The results indicated that the addition of different solid wastes and coal significantly influenced the slagging behavior of sludge. Compared to the combustion of sludge alone, co-firing with coal reduced ash adhesion and weakened particle agglomeration. In contrast, the addition of straw, plastics, and rubber intensified ash agglomeration. High-melting-point crystals of (Ca,Mg)₃(PO₄)₄ (calcium magnesium phosphate) were identified in the ash residues from co-incineration with rubber, plastic, and textiles. Furthermore, analysis of slagging characteristic indices revealed that the addition of coal increased the proportion of acidic oxides in the ash. Calcium in coal promoted the formation of high-melting-point calcium sulfate. The inclusion of wood chips and nitrile rubber alleviated slagging, with a notable reduction in both the base-to-acid ratio and sulfur slagging index. Slagging analysis of ash samples collected from large-scale sludge incineration tests showed that increasing the proportion of solid recovered fuel and extending stable combustion duration helped to reduce slagging risks. These findings provide a scientific basis for further optimization of sludge incineration processes and enhancement of resource utilization efficiency, offering significant practical value.

Key words: sludge, solid waste, co-firing, slagging characteristics

摘要：

近年来，污泥与高热值工业有机固废被广泛作为回收燃料应用于焚烧发电，提升能源回收与固废处置的协同效益。本研究深入分析了这两大类固废掺烧的结渣特性，选取4种典型工业固废与市政污泥作为研究对象，同时以燃煤作为辅助燃料，主要研究了掺烧后灰渣的微观结构特征、矿物相生成特性、结渣特征指数以及大型焚烧现场固废替代煤和污泥掺烧后灰渣结渣情况。结果表明，不同固废与煤的加入对污泥结渣有显著影响，与污泥单独焚烧相比，掺煤燃烧后的灰分黏附程度降低，颗粒间团聚作用减弱，相反秸秆、塑料与橡胶添加后灰渣团聚现象加重；掺混橡胶、塑料及纺织品焚烧后的灰渣中出现(Ca,Mg)₃(PO₄)₄（磷酸钙镁）高熔点晶体。另外，结渣特征指数分析表明，加入煤可提高灰渣中酸性氧化物占比，煤中的钙元素促进高熔点的硫酸钙形成，加入木屑与丁腈橡胶对于结渣情况有所缓解，尤其碱酸比和硫结渣指数显著降低。大型污泥焚烧现场掺烧实验采集灰渣样品的结渣分析结果表明：提高固体回收燃料掺烧比与延长稳定燃烧时间有助于降低结渣风险。以上研究结果为进一步优化污泥焚烧处置工艺、提高资源利用效率提供了科学依据，具有重要的实际应用价值。

关键词: 污泥, 固体废物, 协同焚烧, 结渣特性

CLC Number:

TK16

ZENG Hongfei, JIAO Long, WANG Xu, GUO Qianqian, DENG Kai, HU Yanjun. Slagging characteristics of co-firing process of sludge and solid waste as basic fuels[J]. Chemical Industry and Engineering Progress, 2025, 44(12): 7308-7318.

曾鸿飞, 焦龙, 王旭, 郭倩倩, 邓凯, 胡艳军. 污泥与固废基燃料协同焚烧过程结渣特性[J]. 化工进展, 2025, 44(12): 7308-7318.

Figures/Tables 9

原料	水分/%	灰分/%	挥发分/%	固定碳/%	热值/kJ·kg^-1
污泥	2.38	55.80	41.70	0.12	5674.6
SRF	2.15	11.22	80.82	5.81	18900.7
煤	9.40	27.30	41.8	21.50	21285.4
聚丙烯（PP）	0.03	0.06	99.9	0.01	45655.21
聚苯乙烯（PS）	0.06	0.03	99.55	0.36	40902.54
布料	1.03	0.67	87.01	11.29	22052.33
草编边角料	12.8	0.6	77.65	8.95	19096.25
丁腈橡胶	2.02	23.86	67.19	6.93	21499.41
丁苯橡胶	0.07	0	99.48	0.45	41641.93
木屑	7.84	8.63	69.16	14.37	21621.43
秸秆	7.25	5.46	67.93	19.36	14490.15

原料	C/%	H/%	O/%	N/%	S/%
污泥	21.92	2.98	13.75	1.38	1.80
SRF	54.33	6.47	23.57	0.72	1.54
煤	56.70	3.40	7.30	1.00	0.70
聚丙烯	84.7	13.90	1.4	—	—
聚苯乙烯	90.58	7.76	1.5	—	0.16
布料	61.41	4.27	33.8	0.04	0.48
草编边角料	48.76	6.05	44.44	0.34	0.41
丁腈橡胶	80.47	8.78	1.15	8.76	0.84
丁苯橡胶	89.3	9.54	0.93	—	0.23
木屑	55.1	7.3	36.6	0.9	0.2
秸秆	42.33	5.78	33.07	1.06	0.31

结渣指数	公式
B/A	$B / A = F e 2 O 3 + C a O + M g O + K 2 O + N a 2 O A l 2 O 3 + S i O 2 + T i O 2 × 100 %$
S_R	$S R = S i O 2 S i O 2 + F e 2 O 3 + C a O + M g O × 100 %$
R_S	$R S = F e 2 O 3 + C a O + M g O + K 2 O + N a 2 O A l 2 O 3 + S i O 2 + T i O 2 × S d$
B/A×Na₂O	$B / A × N a 2 O = F e 2 O 3 + C a O + M g O + K 2 O + N a 2 O A l 2 O 3 + S i O 2 + T i O 2 × N a 2 O$
总碱	Na₂O+K₂O
总氯	Cl
硫氯比	S/Cl

结渣指数	公式
B/A	$B / A = F e 2 O 3 + C a O + M g O + K 2 O + N a 2 O A l 2 O 3 + S i O 2 + T i O 2 × 100 %$
S_R	$S R = S i O 2 S i O 2 + F e 2 O 3 + C a O + M g O × 100 %$
R_S	$R S = F e 2 O 3 + C a O + M g O + K 2 O + N a 2 O A l 2 O 3 + S i O 2 + T i O 2 × S d$
B/A×Na₂O	$B / A × N a 2 O = F e 2 O 3 + C a O + M g O + K 2 O + N a 2 O A l 2 O 3 + S i O 2 + T i O 2 × N a 2 O$
总碱	Na₂O+K₂O
总氯	Cl
硫氯比	S/Cl

样品	B/A	S_R	R_S	B/A×Na₂O	总碱	S/Cl	Cl
污泥	2.69	16.97	10.14	4.39	1.63	2.01	0.37
污泥＋煤	2.07	21.63	7.84	3.33	2.02	8.27	0.45
污泥＋聚丙烯	2.29	20.06	7.68	3.34	1.81	26.58	0.12
污泥+聚苯乙烯	2.21	21.06	7.47	3.19	1.84	16.85	2.21
污泥＋布料（含海绵）	2.57	18.16	8.97	3.35	2.06	14.08	0.24
污泥＋草编边角料	2.28	20.75	7.52	3.52	1.92	14.58	2.27
污泥＋丁腈橡胶	2.22	21.68	6.60	3.53	1.95	11.29	2.22
污泥＋丁苯橡胶	2.39	19.37	9.08	3.25	1.70	17.43	0.21
污泥＋秸秆	2.24	20.53	5.35	3.65	2.06	4.07	2.24
污泥＋木屑	2.22	20.19	5.25	3.53	1.97	7.15	2.22

样品	R_S	S_R	B/A		B/A×Na₂O	S/Cl		Cl
颜色标注	0~10%	>10%~20%	>20%~30%	>30%~40%	>40%	轻度腐蚀	中度腐蚀	重度腐蚀
污泥＋煤	-22.77%	27.55%	-23.05%		-24.18%	8.27		0.45
污泥＋秸秆	-47.24%	20.33%	-16.73%		-0.90%	4.07		2.24
污泥＋木屑	-48.56%	18.87%	-17.48%		-2.39%	7.15		2.22
污泥＋丁腈橡胶	-34.28%	27.56%	-17.48%		-1.13%	11.29		2.22
污泥+聚苯乙烯	-26.37%	24.07%	-18.06%		-5.73%	16.85		2.21
污泥＋草编边角料	-25.48%	22.20%	-15.23%		-1.13%	14.58		2.27
污泥＋聚丙烯	-24.13%	18.74%	-14.85%		-23.73%	26.58		0.12
污泥＋丁苯橡胶	-10.47%	14.91%	-11.15%		-6.37%	17.43		0.21
污泥＋布料（含海绵）	-11.64%	7.03%	-4.46%		-2.39%	14.08		0.24

成分	质量分数/%
成分	Fe₂O₃	SiO₂	CaO	Al₂O₃	SO₃	P₂O₅	MgO	Na₂O	K₂O	其他
SRF10%灰渣-1	28.41	19.82	19.31	13.81	8.9	3.86	1.47	1.78	0.43	2.205
SRF10%灰渣-2	26.72	20.57	18.98	14.64	8.85	4.07	1.46	1.99	0.50	2.216
SRF26.5%灰渣-1	25.42	20.42	21.65	13.72	9.09	4.04	1.43	1.48	0.51	2.236
SRF26.5%灰渣-2	24.82	21.25	20.62	14.89	8.52	4.09	1.44	1.59	0.59	2.189
SRF30%灰渣-1	25.97	19.2	20.82	14.57	9.98	3.69	1.31	1.76	0.52	2.177
SRF30%灰渣-2	24.51	22.85	20.29	14.2	8.16	4.05	1.49	1.61	0.60	2.238
未掺烧灰渣-1	33.11	16.02	18.8	13.46	8.65	3.56	1.55	2.21	0.33	2.308
未掺烧灰渣-2	33.24	15.91	18.85	13.27	8.86	3.54	1.56	2.15	0.32	2.298

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