The Study Of Numerical Simulation For Heat Exchanger Of Coke Oven Riser

The new technology of raw-coke-oven-gas waste heat recovery has been an important measure to reduce the energy consumption and raise the utilization rate for coking production. However, this technology is still faced with some problems in the actual application, such as the difficulty in recovering the waste gas and the easy formation of coking. Hence, the in-depth research into heat exchange of the coke oven riser should be conducted to solve those problems above. This paper has made a study of numerical simulation on the law of heat exchange in the coke oven riser and heat exchanger riser, which is presented as follows.1. The Fluent software was a DOpted to make the numerical simulation on the coke oven riser and heat exchanger riser. ICEM-CFD software has been used to build the 3D structural model. For a higher accuracy of calculation, the fluid-solid coupling boundary conditions have been utilized for the simulation. The DO thermal radiation model and k-e turbulence model have been selected.2. The physical properties of raw coke oven gas were processed in the form of polynomial. Based on physical property data of raw coke oven gas in the relevant literatures, the density, thermal conductivity, kinetic viscosity, specific heat capacity and absorption coefficient of the raw coke oven gas have been regressed by the Matlab.3. The coke oven riser with the internal diameter of 400 mm was selected for examination. It is found that the outer wall of infrared imaging riser shot in the field has an average temperature of about 230 degrees. The average temperature of the outer wall in the distribution contour of temperature field captured by the numerical simulation stands at about 226 degrees, which is comparable to the former. Hence, the model is basically reliable.4. The geometric model of the coke oven riser and heat exchanger riser with the internal diameter of 500 mm was selected. According to the numerical simulation of the heat-exchange law for the coke oven riser, vapor heat exchanger riser and water heat exchanger riser, the fluctuation range of the temperature for the internal wall in the three risers are 576-684 ?, 242-436 ? and 130-237 ?. The optimal temperature range of the high-temperature coasting aimed to prevent the coking is between 120 and 300 ?. It is concluded that the high-press water can be used as the optimal solution for heat recovery in the actual production.5. The heat-exchange law of the heat exchanger riser during one coking cycle was simulated numerically. It is found that the temperature range of maximum temperature in the inner wall is 437-570 ?, 241-323 ? and 377-503 ? for the water vapor, high pressure water and heat conduction oil. The fluctuation range of heat recovery rate is 8.48%-41.54%, 12.15%-47.99% and 9.83%-43.89%. Therefore,the use of high pressure water as the heat recovery media is the optimal solution.Moreover, the inlet velocity of the heat recovery media should be raised properly to improve the heat recovery efficiency of heat exchanger riser in one coking cycle.