Isomerization Process by GTC Technology

Isomalk-2 is a broad-range isomerization technology developed by NPP Neftehim, which has been commercially proven in various regions of the world. Isomalk-2 is a competitive alternative to the three most commonly used light gasoline isomerization processes: zeolite, chlorinated alumina and sulfated oxide catalysts.

Isomerization Process by GTC Technology

Isomalk-2 offers refiners cost-effective isomerization options that have consistently demonstrated reliable performance with all standard process configurations, including once-through isomerization, once-through with pre-fractionation, recycle of low-octane pentanes and hexanes, and benzene reduction

Each scheme generates different yield and octane results. The examples given below are for a light straight-run (LSR) process stream, but could also be applied to a reformate stream or some LSR/reformate combinations. In a once-through isomerization process scheme, the LSR is mixed with the hydrogen makeup gas; the mixture is then heated and enters a first reactor where benzene saturation and partial isomerization take place.

The gas-product mixture exits the first reactor, is cooled and fed to a second reactor to complete the isomerization reaction at chemical equilibrium. The product mixture from the second reactor is cooled and fed to a gas separator, where the mixture is separated from the excess hydrogen gas. Excess hydrogen is combined with makeup hydrogen
and fed through the recycle dryers for blending with feed. There is no hydrocarbon feed drying step required.

Saturated isomerate from the separator is heated and fed to the stabilizer. The stabilizer’s overhead vapors are cooled and fed to a reflux drum. Liquid hydrocarbons from the reflux drum are returned to the stabilizer as reflux; while uncondensed light hydrocarbons are separated and sent to the offgas system. The bottom product or isomerate is cooled and sent to gasoline blending.

In an isomerization process scheme with recycle of low-octane hexanes, the isomerate is produced and then fed to a fractionation column(s). Overhead and bottoms isomerate streams are cooled and sent to gasoline blending. A low-octane C6 isomerate stream is recycled back to the isomerization unit.

Prefractionation with low-octane recycle can utilize all of the above methods: prefractionation, isomerization and postfractionation. The prefractionation step consists of de-isopentanization of the feed and/or C7+ separation. The post fractionation step consists of separating the high octane portion of the C5–C6 isomerate and recycling the low-octane C5 and C6 isomerate stream.

Process advantages:
• Process capability to produce 82–93 RON gasoline
• Regenerable catalyst with superior tolerance to process impurities and water
• No chloride addition or alkaline wastes
• Operating temperature range of 120°C–180°C
• Mass yield > 98%, volume yield up to 100%
• Up to 5–6 year cycles between regenerations
• Service life 10–12 years
• Reduced hydrogen consumption vs. chloride systems.

Licensor: GTC Technology

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