| The high temperature air combustion technology is a technology that concernedhighly in the international community, and research and design of methane hightemperature and low oxygen combustion system plays an important role in using thenatural gas rationally and efficiently.In this paper, the FLUENT software is utilized to simulate the working processesof two important equipment which are gas burner and regenerator in HTAC system. Itis obtained that the flow field information inside the two devices and the rules howoperation parameters and structure parameters impact on NO_Xemissions and wasteheat recovery rate. At last, a simple design of HTAC system is made.1. Equilibrium mixture fraction/PDF model, k-ε model, P-1radiation model andNO_Xgeneration model are used in the simulation of methane gas combustion processin the furnace, starting from temperature distribution and NO_Xconcentrationdistribution, different preheated air temperature, oxygen volume fraction, excess aircoefficient and nozzle diameter of furnace combustion condition are respectivelystudied by the simulated calculation. The results show that: Choosing the right and thehigher preheated air temperature can make the furnace temperature distributionuniform, thereby improving the efficiency of the combustion; Under the condition ofair preheating，when the volume fraction of the oxygen in the inlet gas is less than12%, the NO_Xemissions will be maintained at a relatively low level; Excess aircoefficient should not be too high, otherwise it will make NO_Xemissions increase,and the suitable range of α is1to1.3; Smaller nozzle diameter of burner can increasevelocity of gas, enhance turbulent mixing between the gas and air and make thetemperature distribution of the furnace uniform, thereby reducing the amount of NO_Xemissions. Finally, a comparison is made between the simulation results and the dataof the experiment, and both are in good agreement which verifies the reliability of theresults. 2. The calculation model of gas flow and heat transfer processes in ceramichoneycomb regenerator is established. to simulate the regenerator’s start stage, at thesame time, a comparison between the numerical simulation results and the reportedexperimental values is made. It proves the reasonableness of the establishment ofmodel that the results are in good agreement. According to the simulation resultsobtained, an analysis is taken on the flow field and temperature distribution ofregenerator. The topics are studied by the calculation over the effect law of the valve’sswitching time, the excess air coefficient, the hole-sectional shape and the anglebetween cross section and the outer wall on the heat recovery rate of differentregenerators. The conclusion is as follows: Shorter valve’s switching time in the rangeof equipment bearing can contribute to recovering heat of system; When the excess aircoefficient is less than1.3, the smaller the excess air coefficient is, the higher the heatrecovery of the system will be; Heat recovery rate of hexagonal channels regeneratoris the highest, followed by square channels regenerator, and triangular channelsregenerator is the lowest; The smaller the angle between cross section and the outerwall, the better the heat transfer performance of the regenerator will be, but at thesame time, there will be a dramatic increase of the pressure drop, therefore, the costsas well as fan power need to be considered when choosing the right angle.3. According to the design task, simple design calculations of burner, regeneratorand fan are respectively made, and thus establishing a more efficient HTAC system. |
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