A Preliminary Study On The Influence Of H₂O On Combustion Characteristics Of Medium And Low Heat Value Fuel

Since the1960s, countries’ demand for energy is increasingly high while petroleum, natural gas and other non-renewable energy resources are decreasing day by day. So far, China’s fast consuming on energy is threatening the security of energy supply. However, some industries, such as steel industry, chemical industry and metallurgy industry, produce mounts of medium and low heat value fuel some of which are discharged into the air or not utilized cleanly and efficiently. It not only brings pollution but also leads to waste of energy. Fast consuming and severely polluting make the study of clean utilization of medium and low heat value fuel bear both energy-saving and environment-protecting meanings.CO is one of the main component of blast furnace gas(BFG), coke oven gas(COG), pyrolysis gas and other medium and low heat value fuel, and H2O has a complex role on clean combustion of medium and low heat value fuel. So, focused on CO and H2O, this thesis studies the stability of Bunsen burner premixed flame and laminar flame speed with experimental method and numerical method.The main conclusions of this study are as follows:1. In terms of the premixed flame stability: firstly, increasing the Bunsen burner diameter can improve stability and the key to improve stability is controlling the flow speed of combusting region; secondly, the flame stability of CO is poor than CH4; thirdly, compared with CO2, adding N2decrease the flame stability faster; and lastly, adding H2O can reduce the premixed flame stability of CH4while improve the CO stability within certain adding proportion.2. In terms of the laminar flame speed: firstly, adding a small amount of CH4to CO or adding some CO to CH4can enhance the laminar flame speed, but the addition of CH4to CO affects bigger; secondly, adding a small amount of H2O to CO can also improve the flame speed, and the same reason with addition of CH4is that mixing additives generates active radicals like H, OH and so on when in combusting, then increases of the radical concentration of elementary reaction, enhancing the chemical reaction rate, and thus intensifies combustion; thirdly, when the ratio of CH4in the CH4and CO fuel mixture is greater than0.1, four kinds of additives can reduce the laminar flame speed and the order of reducing degree is: CO2>H2O>N2>AR.3. The flame stability and the flame speed is of dialectical unity. In certain conditions, increasing the flame speed is enhancing the flame stability while reducing the flame speed is decreasing the flame stability.