Retrofitting Strategy and Operating Technology of Pure Burning Zhundong Coal in a 135 MW Circulating Fluidized Bed Boiler

doi:10.12096/j.2096-4528.pgt.21107

Abstract

Abstract:

Zhundong coal is rich of alkali metals, and coal ash contains large amounts of Na and K element, which can easily lead to slagging and contamination problems, and affect the normal operation of the boiler. This paper focused on the slagging characteristics of the 2×135 MW circulating fluidized bed (CFB) boilers in the actual operation burning Zhundong coal, and proposed the corresponding renovation plan and operation technology through mechanistic analysis. The results show that increasing the gas velocity at the separator inlet can improve the separation efficiency and circulating rate; increasing the area of platen heating surface and improving the efficiency of separator help to achieve the cooling of the furnace chamber; diluting alkali metal content with pulverized coal boiler ash can reduce the formation of alkali metal sulfate. After the optimization, the target boiler was put back into operation at the original load for about 8 months. The comparison with the operation effect before modification shows that the staining and slagging problems are significantly improved while burning pure Jundong coal at high efficiency and low cost, which verifies the feasibility of the proposed technical solution and also provides a reference for other Jundong coal utilization engineering projects.

Key words: circulating fluidized bed (CFB) boiler, Zhundong coal, contamination, slagging, cyclone efficiency improvement

CLC Number:

TK 16

Hongjian WANG, Haiyang WANG, Hao KONG, Tuo ZHOU, Man ZHANG, Hairui YANG. Retrofitting Strategy and Operating Technology of Pure Burning Zhundong Coal in a 135 MW Circulating Fluidized Bed Boiler[J]. Power Generation Technology, 2022, 43(6): 918-926.

Figures/Tables 10

References 19

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参数	数值
过热蒸汽流量/(t/h)	440
过热蒸汽温度/℃	540
过热蒸汽出口压力/MPa	13.7
再热蒸汽流量/(t/h)	358.8
再热蒸汽进(出)口温度/℃	318.4(540)
再热蒸汽进(出)口压力/MPa	2.71(2.56)
省煤器进口给水温度/℃	248
空气预热器进风温度/℃	20
锅筒工作压力/MPa	14.97

参数	数值
过热蒸汽流量/(t/h)	440
过热蒸汽温度/℃	540
过热蒸汽出口压力/MPa	13.7
再热蒸汽流量/(t/h)	358.8
再热蒸汽进(出)口温度/℃	318.4(540)
再热蒸汽进(出)口压力/MPa	2.71(2.56)
省煤器进口给水温度/℃	248
空气预热器进风温度/℃	20
锅筒工作压力/MPa	14.97

项目	烟气进口温度/℃	烟气出口温度/℃	工质进口温度/℃	工质出口温度/℃	烟气平均流速/(m/s)	过量空气系数
炉膛	—	—	341	345	—	—
屏式过热器	—	—	388	510	—	—
分离器	879	863	341	361	—	1.2
包墙过热器	863	—	361	382	—	1.2
末级过热器	792	636	494	546	13.4	1.2
初级过热器	630	502	382	406	11.5	1.2
省煤器	502	307	248	309	8.02	1.2

项目	烟气进口温度/℃	烟气出口温度/℃	工质进口温度/℃	工质出口温度/℃	烟气平均流速/(m/s)	过量空气系数
炉膛	—	—	341	345	—	—
屏式过热器	—	—	388	510	—	—
分离器	879	863	341	361	—	1.2
包墙过热器	863	—	361	382	—	1.2
末级过热器	792	636	494	546	13.4	1.2
初级过热器	630	502	382	406	11.5	1.2
省煤器	502	307	248	309	8.02	1.2

检测项目	数值
全水分质量分数M_t/%	27.4
空气干燥基水分质量分数M_ad/%	8.76
收到基灰分产率A_ar/%	5.33
干燥无灰基挥发分产率V_daf/%	29.12
收到基固定碳质量分数F_Car/%	47.68
收到基全硫质量分数S_t，ar/%	0.72
收到基碳质量分数C_ar/%	54.46
收到基氢质量分数H_ar/%	3.02
收到基氧质量分数O_ar/%	8.56
收到基氮质量分数N_ar/%	0.50
收到基高位发热量Q_gr，ar/(MJ/kg)	20.91
收到基低位发热量Q_net，ar/(MJ/kg)	19.66