Fry-Drying Process Simulation and Optimization for Low-Rank Coal

Process simulation and optimization for fry-drying of low-rank coal was carried out. The operating conditions of the evaporator was set so that the coal moisture would decrease from 33% to 10% during the drying process. Through process simulations, the heat duty supplied and power consumption were calculated under each operating condition. From the simulation results, the amount of enthalpy supplied and operating costs were calculated on the basis of prices in Indonesia as a coal-producing country and South Korea as a coal-importing country. Cases where thermal energy was reused through MVR showed an effect of reducing enthalpy and operating costs by around 50%. The results indicated that the amount of enthalpy supplied to fry-drying process was minimized at the evaporator pressure of 100kPa and temperature of 120 degrees C. However, the results of optimum operating conditions in terms of operating costs showed a different tendency to depend on the steam and electricity costs. The optimum operating conditions were evaporator pressure 500kPa and temperature 168 degrees C in Indonesia. On the other hand, the optimum operating conditions were evaporator pressure 250kPa and temperature 138 degrees C in South Korea.