| The low metamorphic coals are abundant in North Shannxi. Fine coal with low ash,low sulfur, low phosphorous, high volatile, high heat and high activity is a goodmaterial of low temperature dry distillation. Internal heating type low-temperaturedistillation furnace is the key equipment of carbonization. However, existinglow-temperature distillation technology mainly comes from practice, rather than perfecttheory. Some key parameters of the process such as temperature and pressure aredifficult to measure, the combustion of re-turned gas doesn’t have tangible effects onthe whole process, which directly contribute to reduce the yield of coal tar and the valueof gas.The combustion of re-turned gas, temperature and pressure distribution in thedistillation furnace and the movement of coal tar and dust particles were simulated bycomputational fluid dynamics (CFD) software in this paper. Standard k-ε model, speciestransport model, P1radiation model, porous medium model and two-fluid flow modelwere selected. The research mainly includes the following contents.The simulation results of temperature and pressure distribution show that for lowtemperature dry distillation furnace with75000tons blue coke per year, gas and airburned completely when the gas/air ratio is0.6. The optimal gas/air ratio and total gasflow are1.8and11000m~3/h separately. And the temperature and pressure distribution ofthe furnace under this condition is similar to the measured value in the industry.The simulation results of temperature and pressure distribution of oxygen enrichedcarbonization indicated that promotion of the caloric power of gas and combustion ratecan be achieved by this way. And the temperature and pressure distribution are similarto normal circumstances. A numerical model of coal tar and dust particles motion in the furnace was developed based on the basic equations for two-phase flows. It is found thatwhen the gas flow rate is0.698m/s，coal tar with particle size less than0.2mm and dustwith particle size less than0.18mm are blown out of the tube easily. |
