尿素法SNCR对大型电站煤粉锅炉运行影响的工业试验

doi:10.16085/j.issn.1000-6613.2021-1750

化工进展 ›› 2022, Vol. 41 ›› Issue (7): 3573-3581.DOI: 10.16085/j.issn.1000-6613.2021-1750

尿素法SNCR对大型电站煤粉锅炉运行影响的工业试验

杨希刚¹^,²(), 陈国庆², 黄林滨², 古世军³, 李昌松³, 张勇¹, 金保昇¹()

^1.东南大学能源与环境学院，江苏南京 210096
^2.清洁高效燃煤发电与污染控制国家重点实验室（国家能源集团科学技术研究院有限公司），江苏南京 210023
^3.国家能源集团广西电力有限公司，广西南宁 530007

收稿日期:2021-08-16 修回日期:2021-12-27 出版日期:2022-07-25 发布日期:2022-07-23
通讯作者: 金保昇
作者简介:杨希刚（1975—），男，博士研究生，研究方向为清洁高效燃煤发电技术。E-mail：chengqhit@163.com。
基金资助:
国家重点研发计划(2018YFC1901200);国家能源集团科学技术研究院科技项目(DY2020Y06)

Industrial experiment on the effect of SNCR using urea as the reducing agent on the operation of large capacity power station pulverized coal boiler

YANG Xigang¹^,²(), CHEN Guoqing², HUANG Linbin², GU Shijun³, LI Changsong³, ZHANG Yong¹, JIN Baosheng¹()

^1.School of Energy and Environment, Southeast University, Nanjing 210096, Jiangsu, China
^2.State Key Laboratory of Clean and Efficient Coal-fired Power Generation and Pollution Control (China Energy Science and Technology Research Institute Co. , Ltd. ), Nanjing 210023, Jiangsu, China
^3.China Energy Guangxi Power Generation Co. , Ltd. , Nanning 530007, Guangxi, China

Received:2021-08-16 Revised:2021-12-27 Online:2022-07-25 Published:2022-07-23
Contact: JIN Baosheng

摘要/Abstract

摘要：

在660MW超临界W火焰锅炉上开展了工业试验，研究了尿素法选择性非催化还原脱硝（SNCR）投运对锅炉热效率、NO _x 排放、SCR入口烟道截面NO _x 分布及炉内烟气温度的影响。结果表明：SNCR系统喷入炉内的水汽化吸热是导致锅炉热效率降低的主要原因，喷入炉内水流量增加1.0t/h，锅炉热效率降低约0.05个百分点；稀释水流量影响尿素溶液在炉内的雾化和分配效果，在尿素用量相同条件下适当增加稀释水流量，SNCR脱硝效率会显著提高；相对于试验负荷下约2400t/h的烟气流量，SNCR喷入炉内的尿素溶液流量相对较少（占0.2%~0.5%），因此，对炉内烟气温度影响并不明显。在一定范围内调整稀释水和尿素溶液流量对SCR入口烟道截面NO _x 分布的影响并不明显，但是过低的稀释水流量会影响炉内尿素混合效果，进而影响SCR入口NO _x 浓度在烟道截面深度方向上分布的均匀性。

关键词: 氮氧化物, 选择性非催化还原脱硝, 锅炉热效率, 尿素, W火焰锅炉

Abstract:

Industrial experiments were carried out on a 660MW super-critical down-fired boiler, and the effects of SNCR on thermal efficiency, NO _x emission, NO _x_{distribution at SCR inlet, and flue gas temperature in the boiler furnace were analyzed in detail. The results showed that the evaporation and heat absorption of the water injected into the furnace by SNCR system was the main reason for the decrease of boiler thermal efficiency. when the water flow rate increased by 1.0t/h, the boiler thermal efficiency decreases by about 0.05%. The dilution water flow rate had a significant effect on the atomization and distribution of urea solution in the furnace. Under the condition of the same amount of urea, the denitration efficiency of SNCR could be significantly improved by appropriately increasing the dilution water flow. Compared with the flue gas flow (about 2400t/h) under the test load, the flow of urea solution injected into the furnace was relatively small, accounting for about 0.2%—0.5%. Therefore, it had no obvious effect on the flue gas temperature in the furnace.Adjusting the flow rate of dilute water and urea solution within a certain range had no obvious influence on NO _x distribution in the section of SCR inlet flue, but too low dilution water flow rate would affect the mixing effect of urea in the furnace, and then affected the distribution of NO _x_{concentration in the section of SCR inlet flue.}}

Key words: nitrogen oxides (NO _x ), selective non-catalytic reduction(SNCR) denitrification, boiler thermal efficiency, urea, down-fired boiler

中图分类号:

X773

杨希刚, 陈国庆, 黄林滨, 古世军, 李昌松, 张勇, 金保昇. 尿素法SNCR对大型电站煤粉锅炉运行影响的工业试验[J]. 化工进展, 2022, 41(7): 3573-3581.

YANG Xigang, CHEN Guoqing, HUANG Linbin, GU Shijun, LI Changsong, ZHANG Yong, JIN Baosheng. Industrial experiment on the effect of SNCR using urea as the reducing agent on the operation of large capacity power station pulverized coal boiler[J]. Chemical Industry and Engineering Progress, 2022, 41(7): 3573-3581.

图/表 9

图1 660MW超临界机组锅炉燃烧系统示意图（单位：mm)

图2 SNCR脱硝系统尿素溶液喷射单元（单位：mm）

表1 试验煤质的工业分析和元素分析

工业分析/%					元素分析/ %					低位发热量 /MJ·kg^-1
M_ar	A_ar	V_daf	FC		C_ar	H_ar	O_ar	N_ar	S_ar	低位发热量 /MJ·kg^-1
2.74	26.94	26.64	43.68		53.87	3.43	10.21	0.86	1.95	20250

表2 锅炉热效率试验测量结果

项目	工况1	工况2	工况3	工况4	工况5	工况6	工况7
机组负荷/MW	600	600	600	600	600	600	600
尿素浓溶液(40%)流量 $m u r e a ? s o l u t i o n$ /kg·h^-1	1250	1180	960	783	1495	910	770
稀释水流量 $m d i l u t i o n ? H 2 O$ /kg·h^-1	13144	13046	13152	13520	15500	9325	7791
喷入炉内尿素质量分数/%	3.5	3.3	2.7	2.2	3.5	3.6	3.6
排烟热损失/%	6.5	6.35	6.21	6.65	6.31	6.66	6.16
干烟气热损失/%	5.95	5.81	5.68	6.07	5.73	6.11	5.63
水分热损失/%	0.55	0.55	0.53	0.57	0.58	0.56	0.53
气体未完全燃烧热损失/%	0.19	0.38	0.13	0.06	0.06	0.01	0.06
固体未完全燃烧热损失/%	0.77	1.47	1.74	0.66	1.52	1.16	1.07
SNCR引起的主要热损失/%	0.64	0.64	0.63	0.67	0.76	0.46	0.38
尿素吸热引起的热损失/%	0.04	0.04	0.03	0.03	0.05	0.03	0.03
水吸热引起的热损失/%	0.69	0.68	0.63	0.70	0.81	0.49	0.41
尿素反应引起的热损失/%	-0.09	-0.08	-0.07	-0.05	-0.10	-0.06	-0.05
排烟热损失与SNCR引起的热损失之和/%	7.14	6.99	6.81	7.32	7.07	7.12	6.54
锅炉热效率/%	91.49	90.74	90.88	91.55	90.94	91.30	91.93

表2 锅炉热效率试验测量结果

项目	工况1	工况2	工况3	工况4	工况5	工况6	工况7
机组负荷/MW	600	600	600	600	600	600	600
尿素浓溶液(40%)流量 $m u r e a ? s o l u t i o n$ /kg·h^-1	1250	1180	960	783	1495	910	770
稀释水流量 $m d i l u t i o n ? H 2 O$ /kg·h^-1	13144	13046	13152	13520	15500	9325	7791
喷入炉内尿素质量分数/%	3.5	3.3	2.7	2.2	3.5	3.6	3.6
排烟热损失/%	6.5	6.35	6.21	6.65	6.31	6.66	6.16
干烟气热损失/%	5.95	5.81	5.68	6.07	5.73	6.11	5.63
水分热损失/%	0.55	0.55	0.53	0.57	0.58	0.56	0.53
气体未完全燃烧热损失/%	0.19	0.38	0.13	0.06	0.06	0.01	0.06
固体未完全燃烧热损失/%	0.77	1.47	1.74	0.66	1.52	1.16	1.07
SNCR引起的主要热损失/%	0.64	0.64	0.63	0.67	0.76	0.46	0.38
尿素吸热引起的热损失/%	0.04	0.04	0.03	0.03	0.05	0.03	0.03
水吸热引起的热损失/%	0.69	0.68	0.63	0.70	0.81	0.49	0.41
尿素反应引起的热损失/%	-0.09	-0.08	-0.07	-0.05	-0.10	-0.06	-0.05
排烟热损失与SNCR引起的热损失之和/%	7.14	6.99	6.81	7.32	7.07	7.12	6.54
锅炉热效率/%	91.49	90.74	90.88	91.55	90.94	91.30	91.93

图3 炉膛烟气温度的变化（单位：℃）

图4 锅炉转向室、SCR入口和空预器出口烟气温度变化

表3 SNCR对SCR运行参数的影响

项目	工况1	工况2	工况3	工况4	工况5	工况6	工况7
SCR入口NO _x 浓度(标态干基、6%氧量)/mg·m^-3	369.0	382.5	387.5	439.6	328.5	482.6	508.6
SCR脱硝系统喷氨总量/kg·h^-1	263.0	267.8	270.7	321.1	228.7	346.0	350.0
SCR出口NO _x 浓度值/mg·m^-3	38.2	35.1	37.2	34.6	37.7	33	35.9
SCR入口氨浓度/μL·L^-1	2.38	1.88	1.03	1.33	3.04	2.11	0.87
SCR出口氨逃逸浓度/μl·L^-1	0.23	0.25	0.67	0.59	0.24	0.484	1.10

图5 稀释水流量恒定条件下尿素浓溶液流量对SCR入口烟道截面NO x 浓度分布的影响

图6 喷入炉内尿素质量浓度恒定条件下尿素浓溶液流量对SCR入口烟道截面NO x 浓度分布的影响

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尿素法SNCR对大型电站煤粉锅炉运行影响的工业试验

Industrial experiment on the effect of SNCR using urea as the reducing agent on the operation of large capacity power station pulverized coal boiler

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