摘要
我国化工行业的余热资源主要集中在低温热能,回收率仅41.9%。低温余热资源分布比较分散,传热温差小,回收比较困难,但回收价值可观。压缩机级间气体经过压缩后温度达到160℃以上,在进入下一级压缩之前必须经过冷却。现有工艺以循环水冷却为主,这就造成大量余热资源浪费,同时又消耗大量水资源及电力。有效地利用这部分余热,有着节能减排的重要现实意义。
LiBr低温制冷技术在化工工业上的应用很好解决了低温余热利用这一难题。国内外部分化工企业已经做了尝试和改进,并且取得了不错的效果。本文针对化肥生产压缩工段的氮氢气压缩机级间气体余热回收利用技术与装备开展了研究。主要研究工作和结论如下:
1.提出新流程的方案:三台压缩机低压段三个级间分别放置取热换热器,将75℃热水加热至95℃,用热水驱动溴化锂机组,将13℃冷水降温至8。C,用于新型换热器冷却一入气体。
2.针对安化合成二车间9#、11#、12#氮氢压缩机机组,进行了热力学计算。得到可利用余热量为2164.8kW,选用三洋LCC-51D溴化锂机组,制冷量1477kW,余热全部利用,最大制冷量为1529kW。
3.设计完成换热管涂覆聚四氟乙烯折流杆换热器,并完成强度校核。
4.确定场地需求和设备清单。确定设备投入费用约为268万元。
5.对改进后工艺的经济效益评估。从投入产出,节能节水方面对改造后工艺进行经济性评估,计算出投资回收周期为1.5年。
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.
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