《煤矿通风瓦斯燃烧热反向流式反应器-毕业设计外文资料翻译.doc》由会员分享，可在线阅读，更多相关《煤矿通风瓦斯燃烧热反向流式反应器-毕业设计外文资料翻译.doc（12页珍藏版）》请在taowenge.com淘文阁网|工程机械CAD图纸|机械工程制图|CAD装配图下载|SolidWorks_CaTia_CAD_UG_PROE_设计图分享下载上搜索。
1、英文原文Combustion of Coal Mine Ventilation Air Methane in Thermal Reverse-flow ReactorZHENG Bin ,LIU Yong-qi ,LIU Rui-xiangCollege of Traffic and Vehicle Engineering Shandong University of Technology Zibo City, ChinaAbstract: Combustion of coal mine ventilation air methane(VAM) was investigated in a th
2、ermal reverse-flow reactor.Effects of CH4 concentration, VAM flow and temperature were studied. The results show that combustion of coal mine ventilation air methane be achieved for methane concentration of 0.2%0.8% in reactor. The conversion rates of CH4 are all above 99%.Some heat could be recover
3、ed. With the increase of CH4 concentration and VAM flow, the temperature of middle area increase, the volume of high temperature increase. It is to improve conversion rate of CH4. The lowest combustion temperature is 880 .Keywords:coal mine ventilation air methane; thermal reverse-flow reactor; comb
4、ustion; conversion rateI. INTRODUCTIONWorldwide coal mine methane (CMM) emissions make up approximately 8% of the worlds anthropogenic methane emissions, the quantity of methane emissions from coal mining alone was over 25 million ton every year. Approximately 70% (90% in China) of methane emissions
5、 are from coal mine ventilation air methane (VAM). Ventilation air methane is not only a greenhouse gas but also a wasted energy resource if not utilized. The net calorific power of CH4 emission in VAM every year is equal to that of 33.7 million ton standard coal. As a greenhouse gas, CH4 is over 21
6、 times more effective in trapping heat in the atmosphere than carbon dioxide over a 100-year period. CH4 (17%) is the second largest contributor to global warming after CO2 (55%). Thus recovering and utilizing CH4 properly in VAM is significant in both energy-saving and environment protection 1-4. C
7、H4 concentration in ventilation air methane is usually below 1%. The inflammability limit concentration of CH4 is 4.5%15%. When the concentration is below 4.5%, it cant be ignited or keep burning. So CH4 in VAM is hard to utilize. There are two main utilization techniques. One is CFRR. It employs ca
8、talyst to decrease the autoignition temperature of CH4 and makes CH4 oxidized. The reaction temperature is reduced in this technique, but catalyst is expensive and its reactive activity is greatly influenced by temperature. The processing is complex. The other is TFRR. The heat retainer is heated to
9、 the autoignition temperature of CH4 and CH4 is oxidized. The reaction temperature is a little higher in this technology, but the conversion rate of CH4 is higher. Simple making and low cost favors its large-scale implementation. Now only a few foreign scholars have made some study onutilization 5-8
10、. Nearly no relevant studies have been published in china. Combustion of VAM was investigated in a thermal reverse-flow reactor and effects of operating parameters were studied in this paper.II. EXPERIMENTSThe thermal reverse-flow reactor shown by Figure 1 consists of a combustion reactor, four valv
11、es and a heat output system. The body dimension of the combustion reactor is 2m1m1m. The inner part of reactor is honeycomb ceramics heat retainer and the inner surface of the reactor is ceramics fabric insulation, which makes heat dissipation from reactor surface impossible. An electric heater is i
12、n the middle of the reactor. Twelve thermocouples are laid on the reactor axis. The inner part of the two heat-exchangers is called middle area and four thermocouples are laid here. The outboard of the exchangers is called preheating area, and there are four temperature measuring points each. The te
13、mperature signals are transmitted a computer momentarily. The change of air flow is controlled by four solenoid valves, two forming a group. When valve group 1 opens, valve group 2 closes. The flow direction is from left to right. After a half cyclic period,valve group 1 closes and valve group 2 ope
14、ns. The direction is from right to left. It ensures symmetry of the temperature profile in reactor. The heat output system consists of a drum and two heat-exchangers which are fixed symmetrically.Figure 1. Schematic diagram of the experimental apparatus (1-electric heater; 2-ceramic heat accumulator
15、; 3-heater exchanger)Operating process: The reactor is preheated by electric heater and when the temperature in the middle area is above 950 , VAM is added. VAM is rapidly combusted in the middle high temperature area. The heat of combustion is transferred to ceramics heat retainer and heat-exchange
16、r. Simulated ventilation air methane is produced by natural gas and air. CH4 concentration of natural gas is 99.9%. CH4 concentration of simulated ventilation air methane (CCH4) is 0.2%0.8%. The flow of simulated ventilation air methane (LVAM) is 90 m3h-1180 m3h-1. The cyclic period (t) is 60s180s I
17、II. RESULTS ANDDISCUSSIONA. Temperature Profile Characteristics in Reactor Fig.2 shows the temperature profile in thermal reverse-flow reactor of the two change direction times in one cyclic period. It is clear that the temperature profile is symmetrical, withmiddle high and two ends low. The temper
18、ature of the middle area is higher and stable, which ensures combustion. The temperature of the two ends changes little, with no more than 20 difference. It shows the heat of flue gas loss is low and the heat of combustion is recovered. The temperature profile, orthokinetic changing with the flow di
19、rection, is always dynamic balance. Temperature is unstable in the edge of the middle area. The temperature difference could be as high as 450 500 . This is because the heat-exchangers are set in the edge of the middle area. The heat of combustion is transferred to heat exchangers.Figure 3. Variatio
20、ns of combustion at various temperatures of middle area (experimental condition: LVAM=90 m3h-1; t=90s)Figure 4. Variations of temperature profile at various CH4 concentrations (experimental condition: LVAM=90 m3h-1; t=120s)If cyclic period time is too long, great amount of heat will is transferred t
21、o heat exchanger. This could cause the temperature in the middle area lower than the lowest temperature of combustion and then “flameout” will occur in reactor. Thus, it is important to choose proper cyclic period to ensure the combustion going stably. B. Effect of Temperature on Combustion Temperat
22、ure is an important condition in the realization of VAM combustion 9. Fig.3 shows variations of combustion at various temperatures of middle area. It is obvious that when the temperature is below 870 , the concentration of methane at the outlet is the same with that at the inlet. This shows that met
23、hane cant be combusted at such temperature. When above 880 , the concentration of methane is nearly zero at the outlet, which that this temperature ensures the complete combustion of methane. The lowest temperature of combustion is 880 , and the concentration of methane has no effect on it. Figure 5
24、. Variations of saturation water temperature at various CH4 concentrations (experimental condition: LVAM=90 m3h-1; t=120s)TABLE I. CH4 CONVERSION RATE AT DIFFERENT REACTION CONDITIONS CH4 B. Effect of CH4 Concentration on CombustionFig.4 shows variations of temperature in reactor at various CH4 conc
25、entrations. It is clear that with the increase of concentration, the temperature in the middle area rises, the high temperature area becomes large and combustion area becomes wide, which favor combustion reaction. The temperature of the preheating areas changes little and the difference between temp
26、erature at inlet and outlet changes slightly, showing that flue gas loss hardly changes and that CH4 concentration variation has no effect on it. The extra heat of combustion with the increase of CH4 concentration is recovered totally by the heat output system. The higher the concentration is, the h
27、igher the temperature of saturation water in the drum, as is shown by Figure 5. When the concentration is 0.8%, the temperature of saturation water rises to 140 . The heat could be exported in the form of steam. When CH4 concentration is 0.2%, the temperature in the middle area is about 1000 , signi
28、ficantly higher than the lowest combustion temperature. The conversion rate of CH4 is 99.2% (Table ). It shows that almost total combustion of methane can be achieved, and the additional heat isnt added in reactor. Combustion could be maintained at low concentration of CH4. Tab. shows CH4 conversion
29、 rate at different reaction conditions. It is obvious that when CH4 concentration is 0.2%0.8%, the rates are all above 99%. It shows that at experimental conditions, VAM could maintain combustion reaction in reactor.C. Effect of VAM Flow on CombustionFig.6 shows the variations of temperature profile
30、 at various VAM flows. It is clear that with the increase of VAM flow, the temperature in the middle area rises and the high temperature area becomes wide. When the flow rises to 180 m3h-1 from 90 m3h-1, the highest temperature rises by 50 . The reason is that the increase of VAM flow makes amount o
31、f CH4 combustion increase in one unit of time and more heat is released from the reaction. But the difference of temperature at inlet and that at outlet becomes high. With the increase of flow, the heat that is discharged increase. Flue gas loss increases. The difference between temperature at the i
32、nlet and that at the outlet could be reduced by choosing proper cyclic period and heat loss could be reduced at the same.IV. CONCLUSIONSWhen CH4 concentration is 0.2%, the temperature in the middle area is about 1000 . Almost total combustion of VAM can be achieved, and the additional heat isnt adde
33、d in reactor. CH4 conversion rate is as high as 99.2%. Temperature is an important condition. The lowest temperature of combustion reaction is 880 , and the concentration has no effect on it. Choosing proper cyclic period is important to maintain combustion reaction at low concentration. When CH4 co
34、ncentration is 0.2%0.8%, with the increase of CH4 concentration, the temperature rises in the middle area, the area of high temperature becomes large and combustion zone becomes wide, which favors combustion reaction. CH4 conversion rates are all above 99%. Heat of combustion could be recovered. Whe
35、n CH4 concentration is 0.8%, the temperature of saturation water in the drum can rise to 140 . With the increase of VAM flow, the temperature in the middlearea rises and the high temperature area becomes wide. But flue gas loss increase.Thermal reverse-flow combustion technology is a better method t
36、o decrease the pollution of ventilation air methane, and recover heat.ACKNOWLEDGMENTThis research was supported by Shandong Natural Science Foundation (No.Y2006F63) and Zibo Research Programme (No.20062502).REFERENCES1 Aube F, and Sapoundjiev H, “Mathematical model and numericalsimulations of cataly
37、tic flow reversal reactors for industrialapplications,” Computers and Chemical Engineering, vol. 24, pp. 2623-2632, April 2000.2 Matzos Y S, Noskov A S, and Chumachenko V A, “Theory andapplication of unsteady-state catalytic detoxication of effluent gasesfrom sulfur dioxide, nitrogen oxides and orga
38、nic compound,” Chem EngSci,vol. 43, pp. 2061-2066, August 1988.3 Eigenberger G, and Nieken U, “Catalytic combustion with periodic flowreversal,” Chem Eng Sci, vol. 43, pp. 2109-2115, August 1988.4 Matzos Y S, and Bunimovic G A, “Reverse-flow operation in fixed bedcatalytic reactors,” Catal Rev, vol.
39、 38, pp. 1-8, January 1996.5 Salomons S, Haves R E, and Poirier M, “Flow reversal reactor for thecatalytic combustion of lean methane mixtures,” Catalysis Today, vol.83, pp. 59-69, January 1996.6 Salomons S, Haves R E, and Poirier M, “Modeling a reverse flowreactor for the catalytic combustion of fu
40、gitive methane emissions,”Computers and Chemical Engineering, vol. 28, pp. 1599-1610,September 2004.7 Cimino S, Pirone R, and Russo G, “Thermal stability of perpvskite-based monolithic reactors in the catalytic combustion of methane,” IndChem Res, vol. 40, pp. 80-85, January 2001.8 Chou CP, Chen JY,
41、 Evans GH, and Winters WS, “Numerical studies ofmethane catalytic combustion inside a monolith honeycomb reactorusing multi-step surface reactions,” Combust Sci Technol, vol. 150, pp.27-58, January 2000.9 Krzysztof, “Harnessing methane emissions from coal mining,” ProcessSafety and Environment Prote
42、ction, vol. 86, pp. 315-320, January 2008.中文译文煤矿通风瓦斯燃烧热反向流式反应器郑彬,刘永齐,刘瑞香山东理工大学, 学院交通与车辆工程,淄博市，中国摘 要: 燃烧煤矿通风瓦斯部（VAM）调查了一个热反向流动反应器。甲烷浓度，通风瓦斯流量和温度影响进行了研究。结果表明，煤矿燃烧实现通风瓦斯的甲烷浓度0.20.8时在反应器中。CH4的转化率都高于 99。有些热可以回收。随着甲烷增加浓度与菌根流，中部地区温度增加，高温度的增加量。这是提高甲烷转化率。最低燃烧温度为880。 关键词:煤矿通风瓦斯，热反向流式反应器;燃烧;转化率1 引言 全球煤矿瓦斯（CMM）
43、的排放量弥补约8的世界的人为甲烷排放量，排放的甲烷从煤矿数量单是在每年2500.00万吨。约70（中国90）的甲烷排放量从煤矿通风瓦斯部（VAM）。不通风瓦斯只有一种温室气体，但也是一种浪费能源资源，如果不利用。净发热功率VA菌根甲烷排放每一年等于三三七吨标准煤的。随着一种温室气体，甲烷是超过21倍的更有效的俘获了一个比二氧化碳在大气中的热量100年。甲烷（17）是第二大来源全球变暖后，二氧化碳（55）。因此，回收和利用甲烷在VA菌根正确的意义，既节能保护环境1-4。 甲烷在通风瓦斯浓度一般低于1。易燃的甲烷浓度限制4.515。当浓度低于4.5，但不能点燃或保持燃烧。因此，在VA菌根甲烷很难加
44、以利用。 有两个主要的利用技术。一个是CFRR。这采用催化剂，以减少自燃温度甲烷，使甲烷氧化。反应温度为能在这种技术，但其价格昂贵，催化剂反应活性受温度影响较大。该处理是复杂的。另一种是TFRR。是固定的热量加热到甲烷和甲烷自燃温度氧化。反应温度高一点点在这技术，但甲烷的转化率较高。简单有利于决策和低成本的大规模实施。现在只有少数外国学者的研究已经取得了一些利用5-8。几乎没有相关研究已经在中国出版。 VA菌根燃烧进行了研究一热反向流动反应器和经营的影响参数进行了研究这个文件。2 实验 热反向流式反应器由图1所示由燃烧反应器，四个阀门和热输出系统。对燃烧器车身尺寸是2米 1米 1米。反应器内部
45、是蜂窝状陶瓷热固和反应器内表面陶瓷织物绝缘，这使得反应堆散热表面是不可能的。电加热器是在中间反应堆。图2在反应器温度分布（实验条件：CCH4 0.4; LVAM =90m3. h-1;t= 180s）图1示意图实验装置（1电 加热器; 2陶瓷蓄热器; 3热交换器）十二热电偶是摆在反应器轴。该两个热交换器内的部分称为中部地区和四热电偶奠定这里。该舷外器被称为预热区，并有四个每个测量点的温度。温度信号一台计算机传输瞬间。空气的变化流量控制，由四个电磁阀，二成一小组。当阀门开启1组，2组阀门关闭。该流动方向是从左至右。经过一个半循环周期，阀门关闭，阀门组1组2打开。方向是由右至左。它确保了温度的对称
46、性概况反应堆。热输出系统包括一个鼓两个热交换器是固定对称操作过程：反应器是由电预热加热器时，在中部地区温度高950，VA菌根被添加。 VA菌根在迅速燃烧中高温区。燃烧热的是转移到陶瓷热固和换热器。模拟通风瓦斯是由自然燃气和空气。天然气甲烷含量为99.9。甲烷模拟通风瓦斯浓度（CCH4）是0.20.8。对模拟通风瓦斯流（LVAM）是90m3H-1.循环周期（T）是60180S。3 结果与讨论A.温度反应堆剖面特征图2显示了在热反向流温度曲线这两个反应堆在一个循环周期的变化方向倍。很显然，温度曲线是对称的与中间高，两端低。它的中间温度面积也越来越稳定，保证燃烧。该两端温度变化不大，不超过20差异。
47、它显示了烟气热损失低燃烧热的被回收。温度曲线，或变化与水流方向，始终是 图4温度剖面分布在不同的甲烷浓度 （实验条件：LVAM =90m3. h-1;t= 120s）图3燃烧的变化在不同温度下的中部地区（实验条件LVAM =90m3. h-1;t= 90s）动态的平衡。温度是不稳定的边缘中部地区。温度差异可以高达450500。这是因为热交换器载于在中部地区的边缘。燃烧热的是转移到热交换器。如果循环周期的时间太长，将大量的热量传送到热交换器。这可能导致在中部地区比低的温度燃的最低温度，然后“熄火”会发生在反应器。因此，重要的是要选择适当的循环期，以确保持续稳定的燃烧。B 燃烧中温度的影响图5饱和水温度的变化在不同甲烷浓度（实验条件： LVAM =90m3. h-1;t= 120s） 温度是实现VA菌根燃烧的重要条件9。图3显示了在燃烧变化不同温度下的中部地区。很明显，当温度低于870，甲烷浓度插座是用在进口的相同。这表明， 甲烷燃烧不能在这样的温度。当温度在880以上时，甲烷的浓度几乎是在出口为零，那个这个温度保证甲烷的完全燃烧。低温燃烧是880，并且甲烷的集中没有作用对此。表1 甲烷转化率的不同反应条件CH4浓度( %)VAM流量 （m3. h-1）循环周期(s)CH4转换率（%）0.29012099.20.218012099.40.49012099.