Process Optimization And Energy Saving Research Of 1.4 Million Tons/Year Diesel Hydrofining Unit

With the increasingly strict environmental protection regulations,governments of various countries have successively increased the quality requirements of diesel products.Therefore,the company's diesel hydrorefining or upgrading technology has also been modified or upgraded so that the sulfur,nitrogen content and cetane number of diesel products reach higher standards.In the refinery,in order to produce clean diesel oil that meets the requirements of the standard and reduce the cost of the enterprise,it is necessary to improve the existing production process scheme and optimize the operating technical parameters,optimize the equipment and process to achieve a greater degree of energy saving and consumption reduction.Taking a refinery diesel hydrofining unit in Shaanxi as a research object,the process modeling and optimization of the unit's low fractionation system,fractionation system,heat exchange network,and dry gas desulfurization system were performed using chemical process simulation software Aspen Plus.Based on this,the energy consumption of each link of the device is comprehensively analyzed,and corresponding energy optimization and partial transformation are proposed.The research results obtained are as follows:?1?The software Aspen Plus was used to model the low-separation system,fractionation system,heat exchange network,and dry gas desulfurization system of the hydrogenation unit.The simulation results were in good agreement with the actual operation of the unit and provided for the optimization of the process operating parameters Theoretical basis.?2?On the basis of establishing the process simulation of diesel hydrorefining device,the operating parameters of the separation system are optimized.First,the effect of the inlet temperature of the low-point system on the heat load of the top condenser and the heating furnace at the inlet of the reactor was investigated,and the influence of the operating pressure of the cold and low tank on the C₅⁺loss at the top of the reactor was optimized.When the operating temperature of the device is 205.0?and the operating pressure of the low sub-tank is 2.48MPag,the energy consumption of the public works is reduced by 75.52KW compared with that before optimization.Secondly,the effects of the inlet temperature and stripping steam volume of the desulfurization stripping tower on the heat load of the overhead condenser,the impact of the condenser temperature on the top C₅⁺loss,and the effect of stripping steam volume on the removal effect of hydrogen sulfide are discussed.The optimization result is:when the inlet stream temperature of the top of the stripping tower is 205.0?,the temperature of the air cooler is reduced from 50.0?to40.0?.Although the power consumed by the fan of 70KW·h is increased,the loss of C₅⁺at the top of the tower can be reduced.Reduced the loss of resources;the bottom steam volume was reduced from 2.6t/h to 2.2t/h,saving 0.4t/h low-pressure steam.Next,he influence of the inlet temperature of the fractionation tower on the heat load of the top condenser and the bottom heating furnace,as well as the effect of the change on the product yield of the fractionation tower,and the reflux ratio to the product separation accuracy and its The effect of output is optimized as follows:when the feed to the fractionation tower is 250.0°C and the reflux ratio at the top of the tower is 10.17,the extraction volume of refined diesel increases by 0.22t/h,and the extraction temperature of the bottom diesel decreases from 256.3°C to 252.4°C.The bottom reboiler circulation volume is reduced to 112824.7kg/h,which reduces the use of fuel gas.Finally,the influence of the operating temperature of the dry gas desulfurization tower on the hydrogen sulfide gas removal effect at the top of the tower was discussed,and the influence of the change of dry gas flow rate on the demand of MDEA solution was also investigated.The optimization result was:reducing the temperature of the dry gas into the tower to 27.0?,the H₂S content in the dry gas at the top of the tower reaches the 20.0PPM treatment standard;when the temperature of the dry gas into the tower is constant,the flow rate of the MDEA solution required for the treatment capacity increases linearly,and it can be adjusted according to this law in actual production The flow rate makes the H₂S content of the desulfurized dry gas outlet tower reach the standard,and finally the process flow after the optimization of the device separation system is obtained.?3?Through comprehensive evaluation and analysis of the energy consumption of the device,the analysis and discussion are carried out in three aspects:the diesel heat-feeding heat exchange network,the reaction product pressure,and the power consumption of the pump and the machine,and the need to modify the energy use links of the device Corresponding energy-saving transformation schemes are proposed to maximize the energy consumption of the hydrogenation unit based on the output of qualified products.