Study On The Comprehensive Use Of Interstage Gas’s Waste Heat Of Nitrogen-Hydrogen Compressor

The waste heat resources of China’s chemical industry is mainly concentrated in the low-temperature heat, which recovery rate only41.9%. Low temperature waste heat resources distribution is dispersive and the temperature difference is small, so recovery is more difficult. But the recovery of considerable value. The temperature of gas between the compressor stages reaches160℃, and must be cooled before into the next stage. The existing cooling process is water-cooled, which generated a lot of hot water of waste heat. Effective use of this part of the waste heat, has a practical significance in China’s power shortage conditions.The application of LiBr cryogenic refrigeration technology in the chemical industry solve the difficult problems of take advantage of low temperature waste heat. Part of domestic and foreign chemical companies have been tried and improved the process, and achieved great results. This article is focus on interstage gas waste heat recycling technology and equipment of the nitrogen-hydrogen compressor of the compression section for fertilizer production section to carry out research. Main work and conclusions:1.Propose a new process:recycling heat exchanger were placed to three low pressure stage of three compressor. In which the75℃water ware heated to95℃, to driven LiBr refrigerator unit, cooling13℃cold water to8℃, for cooling the primary entrance gas in the new heat exchanger.2.For the9#.11#,12#nitrogen and hydrogen compressor of the second synthesis workshop of Anhua company, carry out the thermodynamic calculation. Obtained the heat can be used is2164.8kW, selected Sanyo LCC-51D LiBr refrigerator unit, cooling capacity1477kW. All use of waste heat, the maximum cooling capacity for1529kW.3.Design a rod baffle heat exchanger with the heat exchange tubes coated with PTFE,and complete the strength check.4.The space requirements and equipment list is determined. Obtained the equipment investment cost of about$268million.5.Assess the economic benefits of improved process. Do economic evaluation from aspects of input-output, saving energy and water of the new process. Obtained the Investment recovery period is1.5years.