Low temperature isomerization device

Low-temperature isomerization technology is selected for isomerization technology, the Penex-DIH (isomerization reaction-deisohexane tower) process is adopted. The feedstock after denitrification, dechlorination and dehydration were entered into the isomerization reaction unit. After the reaction products were separated by the stabilizer, the bottom products were processed by DIH rectifying tower.The low-octane n-C6 and part of methylpentane in the product are returned to the isomerization reaction unit for further transformation. The pentane component after isomerization and the high-octane dimethylbutane component are separated and distilled by DIH tower top.

Light naphtha from the top of the pre-frittering tower contains 5~10g μg /g of water. After denitrification and desulfurization, isomerized feedstock with nitrogen and oxygen fractions less than 0.1g μg /g are obtained, then enter the feedstock drying and dehydration unit. The supplementary hydrogen from the reforming unit is dechlorinated, desulfurized and deoxidized to obtain hydrogen for reaction with a mass concentration of chlorine, sulfur and oxygen lower than 0.1gμ/L, then enters the feedstock drying and dehydration unit. The feedstock oil after denitrification and desulfurization goes to the feedstock drying and dehydration treatment unit for dehydration treatment to obtain the isomerized feedstock with a water mass fraction lower than 0.1gμ/g, then enters the isomerization reaction unit.

The Penex process adopts two reactors arranged in series with the same amount of catalyst loading. In general, the operation mode of replacing the catalyst in the pre-reactor in four years without regeneration is adopted. During the operation of the device, it is necessary to continuously supplement the chloride additives to maintain the activity of the isomerization catalyst. The excess hydrogen chloride is removed by alkali washing with the dry gas of the stabilizer.

After the isomerization product is stabilized, the bottom product of the tower is transferred to the separation unit DIH of the isomerization product. The top product contains high hydrogen chloride, which needs to be removed by alkaline washing and dechlorination technology. The non-condensing gas after dechlorination enters the pipe network, the liquefied gas is used as the product outlet device.

Because the isomerization products also contain a lot of low-octane n-hexane and methylpentane components, it is necessary to separate n-hexane and methylpentane through DIH and return to the isomerization reaction unit for deep isomerization. The pentane component and high-octane dimethylbutane component are used as isomerization products from the top of the iso-hexane removal tower.A small amount of methyl pentane and other components at the bottom of the tower as a product out of the device.