Preliminary Research On Recirculation Structure In Dome And Lean Blowout Performance Of The Cone-shape Combustion Device

China’s industrial enterprises produced large amounts of medium and low heat value combustible gas every year. However,most of them are directly discharged into the atmosphere,or have not been effective clean use. This not only brings the serious problems of environmental pollution,but also leads to a waste of a lot of energy resources. Gas turbine is charactered by high heat efficiency and low emissions,and these medium and low heat value combustible gases could be used in gas turbine system.So we carried out lean blowout performance experiments for a variety of gaseous fuel in the cone-shape combustion device. And for several typical experiment condition, recirculation structure in dome is analyzed in numerical simulation. What is more,we also analysis and discuss why the center gas pipe jet has a great impact on the combustor lean blowout performance. The research will provide valuable reference for the design of medium and low heat value gas combustor. The main conclusions of this study are as follows:1. In the aspect of lean blowout performance experiments:(1) the center gas pipe flow has important effect on the lean blowout performance of the cone-shape combustion device and the increase of the center gas pipe flow could improve lean blowout performance significantly. (2) When burning CH4+CO and CH4+CO+N2 fuel, the combustor has a higher lean blowout excess air coefficient than CH4 fuel, and this shows that the cone-shape combustion device is suitable for the stable combustion of the fuel which takes CO as the main combustible component. (3) With the increase of fuel’s calorific value in the combustor, the lean blowout performance of the combustor is greatly improved. As the center gas pipe flow of CH4 gradually increase, the energy which is injected into the combustor will reduce per unit time in the experiment process. When the center gas pipe injects more CH4 into the combustor, which not only improves the lean blowout performance of the combustor significantly, but also costs the least total amount of energy at this time. the center gas pipe flow plays a very important role for the combustion stability of the fuel which takes CO as the main combustible component.2. In the aspect of numerical simulation analysis:(1) The total recirculation zone length of the cone-shape combustion device in the center of the flame tube axis is about 250 mm, maximum width of the recirculation region is about 55 mm, which accounts for about two-thirds of the flame tube height, and the recirculation zone structure is not symmetrical. (2) For the cone-shape combustion device, jet flow formed by the center gas pipe inject and rotational flow formed by both sides of the gas pipe together have a stable effect on the flame,but the center gas pipe inject has a greater effect.(3) The area between Z=-45mm and Z=-55mm has the characteristics of low velocity, higher temperature,higher concentration OH components, A good stable ignition conditions formed by the center gas pipe jet may be the cause why the lean blowout performance has been greatly improved.