Research On Ammonia Absorption Refrigeration Technology Applied To Coal Chemical Industry

Coal chemical industry is based on coal as a raw material, through chemical processing, to be coal converted into coal gas, ammonia, methanol, tar, coke, and further into the process of other gas, liquid and solid chemical products, for example urea, olefins etc. Coal chemical process generally includes the gasification of coal, conversion of carbon monoxide, coalgas purification and synthesis process of coalgas products,and there are a lot of industrial waste heat to be produced in coal chemical plants, from the gasification at high temperature、purification process at low temperature, and cooling process for the synthesis gas.While the Processes of the gas purification and synthesis gas cooling and its condensing in a low temperature operation need external capacityiesResidual ammonia water absorption refrigerating machine is as the driving energy from industrial waste heats of steam, water, gas, and others, its using ammonia-water as the working fluid, its cooling capacityies supply the places needing.The device has the adwantage of utilizing low-grade waste and available heat, equipment being simple and easy operation,low cost.It has particularly importance that the device is applicated and promoted in coal chemical industry enterprises,which has abundant heat resurces.In this topic the technology principle and procrss of ammoia absorption refrigeration are analyzed,and technology process and characters are introduced and compared with other onces.Single-stage ammoia absorption refrigeration technology is available for application in coal chemical industry enterprises.The methods of calculation and evaluation are given,and the initial dada,including composition,flow rate etal,are set up.The detailed parameter, balances of mass and heat in system,heat load of equipment,rectiying column,consumes of water and power and et al are calculated.The results show that the refrigerating capacity of the system is 1.179r107KJ/h,cooling water dosage is 1345m3/h,the total unit energy consume is 3288.67KJ/kg,circulation rates of congcertrated and dilute solutions are 77.2m3/h and 62m3/h,respectively.The back flow and generator temperature of fractionating tower are 846.24kg/h and 115℃,respectively.The shaft power and pressure rise of pump are 42kW and 1.26MPa.The temperature drop and pressure drop after trottling are 1.21-1.26MPa and 30.5℃, respectively. The ammonia concentrations are 99.8%,42.4% and 31.5%, respectively.The total dosage of residual heat for transform gas is 2.299x107KJ/h through the ammonia absorption refrigeration unit,and the cooling capacity provided is 1.179×107KJ/h outside.The utilization coefficient of heat energy is 0.513.Therefore,the supply of cooling capacity through the ammonia absorption refrigeration is feasible for low temperature gas purification and syngas cooling processes.