Revamp of LAB Plant

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

The output from the reactor consists of un-reacted paraffin, LAB and HAB (Heavy Alkyl Benzene) forms the feed to the paraffin column. The paraffin column separates the un-reacted paraffin from the product and by-product i.e. LAB and HAB respectively. 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 have high purity and 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 measure of purity of LAB. 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 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 limitation
• The existing distributor and redistributors were found to be inadequate to achieve 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 the quality of distribution

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.