Revamp of LAB Plant

Process overview

LAB (Linear Alkyl Benzene) is the reaction product of n-paraffin and benzene. The LAB plant consists of a PACOL unit (reactor) and recovery unit (paraffin column, re-run column and recovery column).

The output from the reactor consists of un-reacted paraffin, LAB and HAB (Heavy Alkyl Benzene), which forms the feed to the paraffin column. The paraffin column separates the un-reacted paraffin from the product and by-product: LAB and HAB.

The re-run column in the loop then separates LAB and HAB. Further in the recovery column LAB, which has slipped along with bottoms of re-run column, is separated out. The LAB extracted from the re-run and recovery column need to be of high purity and have the desired Acid Color Index (ACI).

Customer requirements
- Maximize recovery of LAB thereby limiting the slippage to < 5%
- Improve Acid Color Index to a range of 20-25
Acid Color Index is the measurement of LAB purity. LAB is mixed with 98% sulphuric acid (H2SO4) and the color index of the LAB sulfonate is measured. Good quality sulfonate (water like color) must have a color index of 20-25.

Problem analysis
Munters studied the existing system; the slippage of LAB in the recovery column was found to be more than 15% and the Acid Color Index was 30-35, sometimes even reaching 60.

It was concluded that:
- The existing pall rings had performance limitations
- The existing distributor and redistributors were found to be inadequate for proper distribution quality

Solution provided:
The LAB plant was hydraulically rated using Medal-Pak® and high-performance distributors. The LAB slippage was found to be within 5-7%.

Recommendations to the customer:
- Replacement of existing Pall Ring with high-performance Medal-Pak® tower packings
- Replacement to high-performance distributors and re-distributors to improve distribution quality

The tower internals and tower packings were manufactured, supplied and installed accordingly.

Results achieved
Plant capacity was increased by 20%. LAB slippage was reduced to less than 5% and the ACI also improved to the desired level.