Characterization of ash deposits from convective heating surfaces in a CFB municipal solid waste incinerator

doi:10.16085/j.issn.1000-6613.2019-0768

Abstract

Abstract:

Ash deposits on convection heating exchanger surfaces reduce their efficiency. Ash samples were collected from a circulating fluidized bed (CFB) municipal solid waste incinerator, which included loose-like fouling and ash deposits from the economizer and evaporating heating exchanger. The composition, microstructure, particle size distribution, surface analysis and the element analysis of those samples were studied with scanning electron microscope (SEM/EDX), X-ray fluorescence (XRF), and laser particle analyzer etc. Results indicated that economizer loose-like fouling contains a high proportion of small and irregularly shaped particles while there are some agglomeration particles among evaporating heating exchanger fouling. The particle size of most fouling of these two kinds is between 0—100μm. The ash fusion temperature of economizer fouling is 80℃ lower than that of evaporating heating exchanger. Besides, the main mineral phase contained in the ash deposits is CaSO₄. Compared to ash deposits formed on the economizer surface, evaporating heating exchanger deposits contain a relatively higher CaO and SO₃ but lower Al₂O₃ and SiO₂. The content of Ca and S from the inner layer of the ash is gradually reduced, while the content of Al and Si is gradually increased. The content of K, Na, Fe and Cl in the inner layer of the ash is higher than that of the other layers.

Key words: fluidized-bed, waste treatment, deposition, convection heating surfaces, alkali metals

摘要：

使用扫描电子显微镜、X射线荧光光谱仪、激光粒度分析仪等分析手段，对流化床垃圾焚烧炉对流受热面的松散性浮灰和烧结性积灰的微观结构和组成成分等进行研究。结果表明，省煤器浮灰中大部分颗粒保持着独立的形态，而对流管束浮灰存在烧结现象；绝大部分的浮灰粒径位于0～100μm；省煤器浮灰的灰熔点低于对流管束浮灰熔点80℃左右；对流管束浮灰和省煤器浮灰在成分组成上差别不大，浮灰中的主要元素均为Ca、Si、Al和S，但对流管束浮灰中Ca和S的含量高于省煤器浮灰。各层积灰中Ca和S的含量较高，主要物相为CaSO₄。对流管束积灰中Ca和S含量高于省煤器积灰；对流管束和省煤器积灰中Al和Si的含量远低于浮灰中的相应含量。从积灰内层到外层Ca和S的含量逐渐减少，而Al和Si的含量逐渐增加；积灰内层K、Na、Fe和Cl的含量高于其他层。

关键词: 流化床, 废物处理, 沉积物, 对流受热面, 碱金属

CLC Number:

X705

Zhi TANG,Xiaoping CHEN,Daoyin LIU,Cai LIANG,Jiliang MA. Characterization of ash deposits from convective heating surfaces in a CFB municipal solid waste incinerator[J]. Chemical Industry and Engineering Progress, 2020, 39(2): 767-775.

唐智,陈晓平,刘道银,梁财,马吉亮. 垃圾焚烧炉对流受热面烧结积灰生长特性[J]. 化工进展, 2020, 39(2): 767-775.

Figures/Tables 14

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样品名称	灰组分质量分数/%
样品名称	SiO₂	Fe₂O₃	Al₂O₃	CaO	MgO	SO₃
煤灰	49.46	4.75	30.80	6.42	1.10	3.83
混合垃圾灰	42.89	5.74	18.49	10.0	2.64	0.94

样品名称	灰组分质量分数/%
样品名称	SiO₂	Fe₂O₃	Al₂O₃	CaO	MgO	SO₃
煤灰	49.46	4.75	30.80	6.42	1.10	3.83
混合垃圾灰	42.89	5.74	18.49	10.0	2.64	0.94

样品名称	变形温度DT/℃	软化温度ST/℃	半球温度HT/℃	熔化温度FT/℃
CF	1270	1280	1290	1290
EF	1190	1200	1210	1210
煤灰	1330	1350	1360	1360

样品名称	变形温度DT/℃	软化温度ST/℃	半球温度HT/℃	熔化温度FT/℃
CF	1270	1280	1290	1290
EF	1190	1200	1210	1210
煤灰	1330	1350	1360	1360

样品编号	各组分的质量分数/%
样品编号	CaO	MgO	SiO₂	SO₃	Fe₂O₃	Al₂O₃	TiO₂	K₂O	Na₂O	Cl
CF	22.13	1.8	23.54	24.94	5.06	13.24	0.9	2.42	2.95	0.17
EF	19.51	2.12	34.48	11.44	6.11	19.03	1.0	1.68	1.28	0.84