The Development And Research Of Porous Medium Burner For The Ultra-low Calorific Gas

Our country has a large number of ultra-low calorific value gas which is released intothe air, so it has formed pollution of environment and the waste of energy. Using porousmedia combustion technology can effectively solve the use of ultra-low calorific value gascombustion, which achieve the effect of energy conservation and emissions reduction.In this paper, the association method of experimental investigation and numericalsimulation is used to design the structure of porous media combustor. The results show thatthe reflow of heat releasing is realized, fire conditions and temperature distribution incombustion chamber are optimized, the intensity of combustion and flame stability areimproved, and the ultra-low calorific value gas combustion conditions are met.Ultra-low calorific value gas in porous media combustion test system is established.Using methane and nitrogen makes2MJ/m3and1.5MJ/m3ultra-low calorific value gas,using the LPG/Air premixed combustion method preheat the combustion chamber, and thencombustion tests are carried out in uniform pattern and gradient porous media burner. It isconcluded that the gradient type for the structure of porous media type has a betterpromoting effect on flame stability than the uniform type for the structure of porous media.Preheating temperature on the low calorific value gas combustion has played a decisiverole, preheating temperature is too low, the flame is extinguished, preheating temperature isexorbitant, tempering fire happened. To guaranteeing the stable combustion, gas calorificvalue is lower, preheating temperature is higher. Under the condition of constantmaintaining combustion intensity, by reducing the gas calorific value, the combustionreaction rate is lower, and the emissions is increased.By using FLUENT software to establish the two-dimensional axisymmetric structureof porous media burner model. After the test results are validated, as an example for the 2MJ/m3and1.5MJ/m3ultra-low calorific value gas, simulations predict the combustioncharacteristics of the three types (uniform type, gradient type and modular type) of porousmedia burner. The results show that under the condition of the preheating temperature formonitoring point remains constant, the ignition in the tail is advantageous to the ultra-lowcalorific value gas combustion, but the preheating time will increase, the modular type forthe structure of porous media is advantageous to the combustion stability of ultra-lowcalorific value gas. Joining metal porous media in preheating chamber (sleeve spacebetween the inner and outer cylinder), due to improving the heat storage ability, flametemperature is higher, it has played a good role for the combustion characteristics ofultra-low calorific value gas as well as the inhibition of the pollutant emissions. Thesimulation results also show that the equivalent ratio is equal to1, ultra-low calorific valuegas combustion produces more carbon monoxide, and it increases with gas calorific valuelower, with the increases of premixed gas flow, when the equivalent down to0.83, thecarbon monoxide emissions has greatly reduced.