Hydrogenation/Hydrodesulfurization Process by Refining Hydrocarbon Technologies

Application: The smart configuration can be applied for selective hydrogenation/hydroisomerization, aromatic saturation and hydrodesulfurization (HDS) of gasoline, kerosine and diesel/distillate desulfurization. In addition, this process can be used for the selective hydrogenation of acetylene, MAPD, C3 /C4 /C5 /C6 /C7 and LCN, hydro-isomerization, benzene saturation and hydrodesulfurization of gasoline, kerosine and diesel/distillate. Multiple catalyst types provide the best performance and lower cost with optimum configuration. The RHT process operates the distillation and reaction units at optimum conditions and integrates the stabilizer with the main distillation column thereby reducing CAPEX and OPEX. By taking multiple draws off from distillation column, it is possible to obtain the highest conversion, high selectivity with low operating costs. The processes apply optimum catalyst and conditions to obtain the best results. The process is optimized for energy consumption via heat integration to provide low CAPEX and OPEX.

pic1 4 - Hydrogenation/Hydrodesulfurization Process by Refining Hydrocarbon Technologies


RHT-Hydrogenation: In the RHT- Hydrogenation process (flow diagram A), the hydrocarbon feed is sent to the distillation column where the feed is treated and taken as a side draw or multiple draw offs. The feed can be treated in an optimum way for catalyst/reactor utilization. Additional liquid is needed to dilute the feed and to maintain reaction temperature. The feed is mixed with sufficient hydrogen to maintain the required for reaction before entering the reactor. The side draw is mixed with liquid from the heat sink and is heated to the reactor temperature. The reactor effluent is sent back to the distillation column to remove light ends/hydrogen at top, and the product is taken as side draw after the pasteurization section. The bottom product does not require further treatment except in the isomerization option.

The process uses metal catalyst used for hydrogenation. Most commonly used catalysts are Pt/Pd, Pd/Ag, Pd, Ni, Ni/Mo, and Co/Mo on silica or alumina base. (Catalysts such as zeolite/Pt can be used aromatic saturation). The process can be optimized for multiple or single catalyst to provide best catalyst utilization and lower cost. The multiple side draws allows heat sink and highest conversions and selectivity required for the process/olefins or saturation. The process uses lower pressure than conventional processes and can work in single phase or two phase reactor operation.

RHT-HDS: FCC Gasoline: The RHT- HDS process (flow diagram B) can be used for FCC gasoline. Processing scheme for straight-run naphtha, heavy gasoil and diesel is similar to conventional schemes. The FCC gasoline is mixed with hydrogen and is heated to moderate temperature. The feed is sent to the selective hydrogenation reactor to remove diolefins to prevent the formation of gums and polymers and coking on the HDS catalyst. The reactor operates in two phases or single phase down-flow reaction mode. Reactor effluent is sent to the splitter where light cut naphtha (LCN) is taken as side-draw overhead and heavy cut naphtha (HCN) is taken from the bottom and medium cut naphtha (MCN) is taken as side draw. The LCN is almost sulfur-free and contains less than 3 to 5 wppm mercaptans and other sulfur compounds. DMS is essentially eliminated or minimized.

The HCN is taken from bottom of the splitter and is mixed with hydrogen required for HDS and is heated to the desulfurization temperature in the furnace. The feed is fed to the HDS reactor in down-flow mode. The HDS occurs in the catalyst zone at high temperatures to support high desulfurization rates HCN, which contains the maximum sulfur level and is the most refractory. The MCN is also mixed with hydrogen and heated to the reactor temperature and is sent the HDS reactor around the middle of reactor. The space velocity for HCN and MCN depends on the total sulfur concentration in both streams and the sulfur-containing species. Another consideration for the catalyst quantity is based on the product specifications required. The reactor effluent is sent to stabilizer, where residual sulfur is driven from the MCN and HCN product and is taken as the bottom product from stabilizer.

The catalyst used for first reactor for selective hydrogenations are Pt/Pd, Pd, Ni, Ni//W or Ni/Mo depending upon the feed and operating conditionsselected. Catalyst required for HDS include Co/ Mo, Ni/W or Ni/Mo. RHT processes do not use any internals. Additionally, if the capacity must be increased for future processes with special internals become a bottleneck and one has to install complete additional train, which is very expensive.

RHT-HDS: Gasoil/diesel: RHT has a configuration to desulfurize the crude and vacuum unit pumparound and main fractionators side draws at the location with staggered pressures so that hydrogen can be spilled into lower pressure unit, gasoil, diesel/kerosine/naphtha in that order. The flow schemes are similar to conventional processes with reactor internals designed to meet high-distribution efficiency. The catalyst is same as mentioned above earlier, e.g., Co/Mo, Ni/W, Ni/Mo. Zeolite/Pt catalyst and Ni is used for light cycle oil (LCO) aromatic saturation and ring opening.

Licensor: Refining Hydrocarbon Technologies LLC.

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