Research On Combustion Technology Of Pyrolysis Gas

Compared with traditional gas turbine, chemically recuperated gas turbine has many advantages, such as lower heat loss, higher combustion efficiency in part-load conditions, lower thermal radiation and lower emission pollution. But the combustion chamber must be reconstructed or redesigned in order to make a gas turbine combustion chamber with diesel oil as fuel in order to burning pyrolysis gas efficiently and cleanly. The numerical simulation of pyrolysis gas's combustion flow field in this dissertation was valuable in improving the quality of combustion field and guiding the reconstruction of the combustion chamber.The combustion flow fields of a combustion chamber were simulated with FLUENT software. During the numerical simulation, the k-εturbulence model, a single chemistry reaction system, infinite-rate reaction, upwind discretization scheme and the SIMPLE algorithm were applied. The main work and conclusions of this dissertation were as follows:1. For the combustion chamber without film holes: 1) The combustion flow fields of fuel oil were simulated, then the nozzle was reconstructed, and the combustion flow fields of pyrolysis gas were simulated too. The results showed that along with the reduction of the load, the combustion efficiency reduced, excess air ratio increased, the length of flame shortened. After the fuel was changed to pyrolysis gas, the total enthalpy of the combustor's outlet increased, the combustion efficiency enhanced, the average temperature of flame tube reduced. 2) The diameters of primary hole and dilution hole were changed, and the corresponding combustion fields were simulated. The results showed that along with the reduction of the diameter, excess air ratio of the combustor's foreside increased, the length of flame shortened, the evenness of outlet temperature field was improved.2. The combustion flow fields of the combustion chamber with film holes were simulated. The results showed that the average temperature of flame tube was lower than that of the combustion chamber without film holes, but the length of flame was longer, so the evenness of outlet temperature field was worsen.3. In view of the problems in the combustion field, two methods of improvements were proposed and the corresponding combustion fields were simulated. According to the simulation, some conclusions can be gained. 1) The evenness of the flame tube's temperature was improved when the walls below the film holes were removed, but the average temperature was increased. 2) The evenness of outlet temperature field was improved after one half of the total film holes were removed, and at the same time, the average temperature of flame tube was acceptable.By the numerical simulation in this dissertation, the characteristics of pyrolysis gas's combustion field are well known. The work of this dissertation is valuable in optimizing the combustion chamber.