The main methods to reduce the sulfur content of diesel oil: 1, FCSH diesel oil countercurrent hydrogenation deep desulfurization and dearomatization process.
FCSH process is that fresh hydrogen or hydrogen from circulating hydrogen desulfurization tower enters from the bottom of the reactor, raw oil enters from the upper part of the reactor, and oil and gas contact reversely to complete the reaction; The upward flow of gas makes the harmful gases H2S and NH3 produced in the reaction process be taken out of the catalyst bed in time, thus greatly improving the reaction depth of hydrodesulfurization and hydrodearomatization. At the same time, because cold hydrogen enters the countercurrent reactor, the reactor temperature will drop from top to bottom along the axial direction, which is beneficial to the deep dearomatization of diesel oil.
FCSH has obvious advantages in ultra-deep desulfurization effect, aromatic saturation, density reduction and cetane number increase, which can better meet the needs of producing diesel oil meeting Euro V emission standards.
2.FDAS two-stage deep desulfurization and dearomatization process
FDAS technology is to use conventional catalyst for hydrofining first, and then use non-noble metal catalyst for deep hydrogenation saturation at medium pressure, so as to achieve the purpose of deep hydrodesulfurization, dearomatization and cetane number improvement of diesel oil, and obtain low sulfur and low aromatic diesel oil. The two-stage method can obviously reduce the contents of organic nitride, ammonia and hydrogen sulfide, which is beneficial to aromatic saturation reaction.
3. Liquid-phase circulating hydrogenation process of 3.SRH diesel oil
SRH downflow diesel liquid phase circulating hydrogenation technology relies on the dissolved hydrogen brought into the reaction system during the circulation of a large number of liquid products to provide hydrogen for the hydrogenation reaction. The reactor adopts a structure similar to trickle bed reactor.
4. RTS ultra-deep hydrodesulfurization process for diesel oil
RTS ultra-deep desulfurization technology for diesel oil uses one or two non-noble metal hydrofining catalysts, and two stages pass through the distillation range once, so that ultra-deep desulfurization of diesel oil can be completed through two reactors. The first reactor carries out deep desulfurization and denitrification at a higher temperature, and most of the easily removed sulfides and almost all the nitrides are removed in the first reactor; The second reactor removed the nitride, completed the complete hydrogenation saturation of the residual sulfide, and improved the color of the oil at a lower temperature.