二次风入射角度对W型火焰炉炉内单相流动的影响
摘要
W型火焰锅炉以其自身的炉膛温度高、火焰行程长等特点,适于燃烧无烟煤等低挥发分燃料。目前我国已投运了60余台W型火焰电站锅炉,在实际运行过程中积累了很多十分宝贵的经验,但仍有一些问题亟待解决。
本文针对某厂FW技术1025t/h W型火焰锅炉飞灰含碳量较大,火焰稳定性差,过热器超温,减温水量大等问题,搭建了根据原炉膛1:15缩小的冷态模化试验台,利用恒温热线风速仪系统对不同工况下炉内的流动状况进行了单相试验。试验研究发现:现运行工况存在拱上主气流下行深度过浅,火焰行程较短,炉膛充满度较低等问题。通过增加F层二次风射流的下倾角度可以解决原有工况存在的问题。随着下倾角度的增加,火焰行程增加,炉膛利用率提高,能促进煤粉的燃尽,炉内结渣情况也得到好转。但当射流角度过大时,容易引起冲刷冷灰斗,喉口结渣等问题。在F层二次风以一定射流角度下射的同时,加入一定量的E层二次风,能够很好的促进一、二次风的混合,有利于煤粉气流的及时着火,并能更好的保护侧墙不受烟气的冲刷,达到分级送风的目的。但当E层二次风过大时,会引起火焰短路、冲刷喉口等一系列问题。
W型火焰炉自身特定的燃烧特性决定了这种炉型NOx生成量非常大,因此在通过将二次风下倾增大煤粉燃尽率后,还需在拱上通入燃尽风的手段来减少NOx的生成。在原有二次风下倾试验台的基础上,另外加装了OFA盆口,对其炉内流场进行了研究。我们发现,OFA的加入下炉膛流场的整个形态影响不大,能够保持原有的流场形势:火焰行程长、炉膛利用率高、结渣可能性小等。
W-shaped boilers are suitable to burning low volatile fuel like anthracite because of the high temperature in furnace, long-flame, etc. At present, near sixty W-shaped boilers are operating in many Chinese large-scale power stations. Many operation experiences are accumulated in China, yet there are some problems to be solved.
Aimed at high heat loss due to solid unburned combustibles, combustion dis-stability, superheater temperature excursion, quantity desuperheat water, etc, in a 1025t/h full-scale utility W-shaped boiler which was designed and produced by DongFang Boiler Works according to the technique introduced from F&W Co. Ltd of USA, the aerodynamic fields were studied on the single-phase cold model, which was built on the Similarity Theory by 1:15. An IFA300 constant-temperature anemometer system was used to measure the air velocity in the model. The experimental results reveals that there is a W-shaped flame in the furnace under the present work condition, but the pulverized coal flows too short to burn out, and the dregs under the arch is caused by the back-coming eddies near the burner. Flame journey increased, furnace using rate enhanced that will advance pulverize coal burnout and ameliorate slag through increasing F-secondary air declination angle. However, large jet angle will easily arouse eroding furnace hopper, arch slag, etc. Entering some E-secondary air will be good for mix between primary and secondary air, pulverize coal ignition in time, protect side wall no to erode by flue gas better, and air grade. Yet, when the E-secondary air was supplied too more, flame will short and arch will be erode.
This W-shaped boiler has a large NOx emission because of the combustion characteristic, so that after declination secondary air to increase pulverize burnout, OFA on the burnout chamber must be supplied to reduce NOx emission. In this thesis, OFA spouts are fit in the test-bed to study the flow field. The results show that the flow field keep primary position that Flame journey increased, furnace using rate enhanced, and slag feasibility reduced, etc, due to OFA air influenced flow field little.
本文针对某厂FW技术1025t/h W型火焰锅炉飞灰含碳量较大,火焰稳定性差,过热器超温,减温水量大等问题,搭建了根据原炉膛1:15缩小的冷态模化试验台,利用恒温热线风速仪系统对不同工况下炉内的流动状况进行了单相试验。试验研究发现:现运行工况存在拱上主气流下行深度过浅,火焰行程较短,炉膛充满度较低等问题。通过增加F层二次风射流的下倾角度可以解决原有工况存在的问题。随着下倾角度的增加,火焰行程增加,炉膛利用率提高,能促进煤粉的燃尽,炉内结渣情况也得到好转。但当射流角度过大时,容易引起冲刷冷灰斗,喉口结渣等问题。在F层二次风以一定射流角度下射的同时,加入一定量的E层二次风,能够很好的促进一、二次风的混合,有利于煤粉气流的及时着火,并能更好的保护侧墙不受烟气的冲刷,达到分级送风的目的。但当E层二次风过大时,会引起火焰短路、冲刷喉口等一系列问题。
W型火焰炉自身特定的燃烧特性决定了这种炉型NOx生成量非常大,因此在通过将二次风下倾增大煤粉燃尽率后,还需在拱上通入燃尽风的手段来减少NOx的生成。在原有二次风下倾试验台的基础上,另外加装了OFA盆口,对其炉内流场进行了研究。我们发现,OFA的加入下炉膛流场的整个形态影响不大,能够保持原有的流场形势:火焰行程长、炉膛利用率高、结渣可能性小等。
W-shaped boilers are suitable to burning low volatile fuel like anthracite because of the high temperature in furnace, long-flame, etc. At present, near sixty W-shaped boilers are operating in many Chinese large-scale power stations. Many operation experiences are accumulated in China, yet there are some problems to be solved.
Aimed at high heat loss due to solid unburned combustibles, combustion dis-stability, superheater temperature excursion, quantity desuperheat water, etc, in a 1025t/h full-scale utility W-shaped boiler which was designed and produced by DongFang Boiler Works according to the technique introduced from F&W Co. Ltd of USA, the aerodynamic fields were studied on the single-phase cold model, which was built on the Similarity Theory by 1:15. An IFA300 constant-temperature anemometer system was used to measure the air velocity in the model. The experimental results reveals that there is a W-shaped flame in the furnace under the present work condition, but the pulverized coal flows too short to burn out, and the dregs under the arch is caused by the back-coming eddies near the burner. Flame journey increased, furnace using rate enhanced that will advance pulverize coal burnout and ameliorate slag through increasing F-secondary air declination angle. However, large jet angle will easily arouse eroding furnace hopper, arch slag, etc. Entering some E-secondary air will be good for mix between primary and secondary air, pulverize coal ignition in time, protect side wall no to erode by flue gas better, and air grade. Yet, when the E-secondary air was supplied too more, flame will short and arch will be erode.
This W-shaped boiler has a large NOx emission because of the combustion characteristic, so that after declination secondary air to increase pulverize burnout, OFA on the burnout chamber must be supplied to reduce NOx emission. In this thesis, OFA spouts are fit in the test-bed to study the flow field. The results show that the flow field keep primary position that Flame journey increased, furnace using rate enhanced, and slag feasibility reduced, etc, due to OFA air influenced flow field little.
引文
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28. S. Benyahia, H. Arastoopour. Simulation of Particles and Gas Flow Behavior in The Riser Section of a Circulating Fluidized Bed Using the Kinetic Theory Approach for the Particulate Phase. Powder Technology. 2000, 112:24~33
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34.田新荆,万中平,林协丰.W型火焰锅炉冷态流场的研究.湖北电力, 2002, 26 (1):20~23
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2.赵洁,王建军,范剑峰.中国能源现状及发展前景分析.科技经济市场. 2006, (8):13~14
3.黄生琪,周菊华.我国节能减排的意义、现状及措施.节能技术.2008(2)
4.许传凯,许云松.我国低挥发分煤燃烧技术的发展.技术经济综述.2001
5.赵仲琥,何佩鏊,秦裕琨.煤粉燃烧器设计与运行.机械工业出版社.1986
6. Joseph G. Singer. Combustion Fossil Power Systems (Third Edition). Combustion Engineering. INC.1981.
7.任玉明.中国无烟煤资源与性质.洁净煤技术. 2004, 10(3): 8~10
8.柳宏刚,白少林.现役各类W火焰锅炉NOx排放对比分析研究.技术经济综述.2007
9.车刚,徐通模,惠世恩.W型火焰锅炉空气动力场的研究.山东电力技术.2007(5):20~25
10.毕玉森,陈国辉.低挥发分煤种与W型火焰锅炉.热力发电. 2005, (7):7～10
11.车刚,郝卫东,郭玉泉.W型火焰锅炉及其应用现状.电站系统工程. 2004, 20(1):38~40
12. John Reason. How Fuel Volatility Impacts Boiler Design and Operation. Power. 1983,(12):145~148
13. W. J. Peet, V. Kanan. Utility Boiler Design for Low Voltile Coals. Coal Combustio. Beijing ,1998
14. N. A. Burdutt. The Effects of Air Staging on NOx Emissions from a 500 MWe Down-fired Boier. Journal of the Institute of Energy, 1987, (4):62~66
15. S. C. Stultz, J. B. Kitto. Steam/Its Generation and Use. 40th edition B&W Barberton, Ohil, U.S.A, 1992
16.车刚,孙新国,王涌,周屈兰,窦文宇,惠世恩,徐通模.W型火焰锅炉结构改造的实验研究.西安交通大学博士毕业论文,1999
17.郭玉泉.W火焰锅炉燃烧及运行特性试验研究.山东大学硕士毕业论文.2006
18.袁颖,相大光.我国W火焰双拱锅炉燃烧性能调查研究.中国电力,1996,32(11):1~6
19. W. M. Robsenowetal. Handbook of Heat Trailsfef. Mc Graw Hill, 2001
20.余岳溪,李乃钊,罗萌,徐齐胜,宋景慧,温智勇.W形火焰锅炉的风量和煤粉均匀特性对燃烧的影响.广东电力,2002,15(3):16~18
21.熊蔚立,龚柏云.W型火焰下喷燃烧锅炉技术特点及选型参考.湖南电力. 1999, 6
22.郭晓宁. W型火焰锅炉对低挥发分煤的适应性及其燃烧系统的设计分析.热能动力工程. 1996, 11(3):20~25
23.何立明,车刚,徐通模,惠世恩,谭厚章,闫晓,许卫疆.炉膛喉口面积对W型火焰锅炉炉内空气动力场的影响.西安交通大学硕士毕业论文. 2000
24.车丹等,W型火焰锅炉燃烧特性的研究.太原理工硕士毕业论文.2006
25.高原. 1025t/h W型火焰锅炉气固流动特性的数值模拟研究.哈尔滨工业大学硕士毕业论文. 2005
26.柳红刚,白少林.现役各类W火焰锅炉NOx排放对比分析研究.热力发电. 2005, 25(5):628~632
27.张海,吕俊复等. W型火焰锅炉燃烧问题的分析和解决方法.动力工程. 2007, (3):1~9
28. S. Benyahia, H. Arastoopour. Simulation of Particles and Gas Flow Behavior in The Riser Section of a Circulating Fluidized Bed Using the Kinetic Theory Approach for the Particulate Phase. Powder Technology. 2000, 112:24~33
29.张文宏.W型火焰锅炉炉内空气动力场的试验研究.动力工程1992, 12(4): 14~23
30.孙保民,陆肖马,徐旭常.W型火焰煤粉锅炉炉内冷态流场的试验研究及数值模拟.燃烧科学与技术,1995, 1(1)
31.何立明,张建邦,李晓勇,车刚,徐通模,惠世恩.燃烧器配风对W型火焰锅炉炉内空气动力场影响的实验研究.应用力学学报. 2002, 19(1):18~22
32.车刚,何立明,徐通模,惠世恩.燃烧器角度对W型火焰锅炉空气动力场的影响研究.动力工程. 2001, 21 (1):1132~1136
33.何立明,车刚,徐通模,惠世恩,谭厚章,闫晓,许卫疆.炉膛喉口面积对W型火焰锅炉炉内空气动力场的影响.西安交通大学硕士毕业论文, 2000
34.田新荆,万中平,林协丰.W型火焰锅炉冷态流场的研究.湖北电力, 2002, 26 (1):20~23
35. D. B. Spalding.Mathematical Modles of Continuous Combustion, Emissions From Cotinuous Combustion System. Plenum Press, 1972
36. D. B. Spalding. Basic Two-phase Flow Modeling in Reactor Sagety and Performance. ERRI Workship Proceedings. 1980, (2)
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