| As a main transportation fuel, the demand of diesel has been increasing year by year. But the emission with nitrogen and sulfide can cause serious atmospheric pollution after diesel combustion, because the diesel contains non-hydrocarbons such as nitrogen and sulfur compounds. In 2017, diesel’s quality which towards ultra low sulfur, low aromatic and high cetane rating has to meet the national V standard.In this paper, the 180×104 t/a diesel hydro-upgrading unit was studied and the process scheme of reaction, recycle hydrogen desulfurization and fractionation were well designed.In reaction section, one-stage serial hydrotreating process was selected, hydrofining reactor and hydro-upgrading reactor were set; automatic backwash filter was used for feed oil; at the same time, inert gas was introduced to prevent from oxidation of feed oil; The feed mixed with hydrogen before entering the furnace, and reaction injection and Hot HP process was used. After the process determined, process model was established by simulation software through the calculation of raw material, product and operation conditions. The hydrogen consumption, heat balance and pressure balance were also calculated by the model.In recycle hydrogen desulfurization section, desulfurization model was established. According to the model, top operating pressure was 11.0 MPa(a), operating temperature was 50℃,12 actual plates were used and the consumption of lean amine was 30 t/h.The fractionation section contains diesel stripper and fractionator. By analysis of simulation model,10 theoretical plates were used in stripper while the steam volume was 3.8 t/h; 17 theoretical plates were used in fractionators,and feed temperature was 240℃ while feed position was at the tenth plate. The content of H2S in naphtha oil and diesel were separately less than 1 ppm and 10 ppm.Finally, the key operating conditions, process characteristics and brief process description were summarized. |
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