1、翻 译部 分英文原文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 i
2、n a thermal 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 r
3、ecovered. 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
4、; combustion; 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 emi
5、ssions 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 o
6、ver 21 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
7、1-4. CH4 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 empl
8、oys catalyst 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 hea
9、ted to 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 onutilizati
10、on 5-8. 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, fou
11、r valves 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 heate
12、r is in 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.
13、The temperature 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
14、 2 opens. 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 accum
15、ulator; 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-ex
16、changer. 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 III. RESULTS ANDDISCUSSIONA. Temperature Profile Charac
