| According to the working condition of an intermittent coal gasifier in a company, the paper gave an investigation on the device structure, process and other aspects of operation by computer technology. The actual production conditions were visualized by numerical simulation. The design parameters were adjusted through the distribution of physical quantities inside the model, and the main work was as follows:1) According to the chemical kinetics principle, this paper has simulated the various reactions in the furnace and elucidated that the main factor impacting the gasification efficiency was fluctuated in the furnace heat storage. It showed us that the gasifier efficiency was linked to the heat storage closely, and it couldn't provide sustained heat, which led to low efficiency in the furnace.2) The paper used porous media model of Fluent for simulating cold flow field in the coal gasification furnace. Compared with the production data, it showed that it was feasible to adopt porous media model in intermittent coal gasifier simulation. Moreover it demonstrated that the changes of media clearance rates would affect the distribution of gasification agent. The distribution of air have tendency to focus on the center of grate. And if the void fraction changed, the region of the largest air distribute would also change, which was one of the main reasons leading to the fluctuation of status.3) Numerical simulations were taken on different structures under different conditions so that designers could obverse the distribution of temperature, velocity, concentration of CO, H2 and water vapor intuitively and precisely in the gasification furnace, which could provide strong technical support for designing and optimizing coal gasifiers. But it was fantastic for experiments. For the deficiencies of existing grate, a new grate was developed, and qualitative research was made on grate optimization with reference to the latest research technology at home and abroad. Changing the grate's various parameters for simulation and comparing the content of efficient gases about CO and H2 in the results, the four optimization measures were as follows:increasing the furnace wall insulation, using straight edge grate, increasing each tilt angle for each grate, adjusting the air distribution. And to integrate with the four measures could increase the gas efficiency of 38.1%.4) By studying the down clean air, the purification mechanism was illustrated on the furnace grate. Folding inside and outside of each grate produced three deceleration zones in the flow channels which were the main areas of particle deposition and the setting down particles stopped by folding inside were blown into the grate by air flow. By the research, it would optimize the best dip angle at 20°for each grate. To improve the final optimized for the grate parameters, applying the three regional distribution theory to re-adjust the air distribution of the grate gap, We would achieve the distribution of gasifying agent at the grate inlet. At the same time we could raise the efficiency of the gasification process by improving flow field, temperature field in the furnace. Compared with the original grate, it was indicated that the new could reduce the time in heat storage, the heat loss of furnace wall and the air flow, and besides increase the heat storage in the furnace. It could confirm that the new grate increased the effective gas by 2.9% in the product gas and improved the steam utilization significantly. So it could save energy and increase the production competitive forces. |
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