Analysis of flue gas deep waste heat recovery with cooperative flue gas pressure control for alkane dehydrogenation heating furnace
The refinery heating furnace is one of the high energy consumption and high carbon emission equipment in the petroleum refining process.Flue gas waste heat recovery of the refinery heating furnace plays an important role in reducing pollutants and carbon emissions for petrochemical industry,but low-temperature flue gas condensate can corrode heat exchanger,and the flue gas condensing heat exchanger(FGCHE)added at the rail of heating furnace increases flue gas pressure drop,affecting refinery production process and the combustion efficiency of the heating furnace.The anti-corrosion,high-efficiency and low-pressure-drop FGCHE with cooperative flue gas pressure control become technical challenges to improve the maximizing energy efficiency of flue gas heat recovery and utilization system.Taking alkane dehydrogenation heating furnace in the refining plant as an example,the low-temperature flue gas deep waste heat recovery with cooperative flue gas pressure control system(FGHR-PCS)was proposed,and its demonstration project was established,then the FGHR-PCS under the working conditions both of stepped and no-stepped heat transfer was tested on site.Energy-saving operating characteristics were analyzed and compared with the theoretical value.The results showed that the accuracy of flue gas pressure in the heating furnace chamber control reached(-35±6.4)Pa,meeting the requirement of the production process.Meanwhile,the flue gas temperature of the alkane dehydrogenation heating furnace was reduced from 178.3-178.7℃to 54.3-78.7℃,the energy saving efficiency reached 4.75%—6.9%,the flue gas waste heat recovery ratio reached 28.1%—40.4%,the flue gas heat recovery amount in the stepped heat transfer stage was 43.8%higher than that in the no-stepped heat transfer stage,and the exergy efficiency of the FGCHE reached 52.8%—63.7%.At the same time,the flue gas energy saving of the FGHR-PCS was beneficial to reduce carbon and pollutant emissions(NOx and SO2),and the carbon reduction emissions could reach 2884.5-4197.9t/a,which provided the FGHR-PCS had remarkable benefits on energy saving,pollution emission and carbon reduction.It can provide a practical application reference for the technology development and application of the low-temperature deep waste heat recovery from refining heating furnaces.
heating furnaceflue gas waste heatwaste heat recoverystepped heat transferflue gas pressure control
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