Revamp of LAB Plant

Customer:	Petrochemical industry.
Location:	Western India.
Tower Name:	Paraffin recovery unit
Tower Diameter:	1200 mm to 4500 mm.
Mass Transfer Equipment:	Medal-Pak tower packings and tower internals

History:
Company is leading manufacturer of petrochemicals.

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, Rerun column and Recovery column).

The output from the reactor consists of un-reacted paraffin, LAB & HAB 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 (Heavy Alkyl Benzene) respectively. The Rerun column in the loop then separates LAB and HAB. Further, in the recovery column LAB which has slipped along with bottoms of rerun column is separated out. The LAB extracted from the rerun & recovery column need to have high purity & desired Acid color index.

Customer Requirements:
- Maximize recovery of LAB thereby limiting the slippage to < 5%
- Improve acid color index (ACI) to a range of 20 to 25.

[ ACI is the measure of purity of LAB. LAB is mixed with 98% 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:

KEVIN studied existing system; the slippage of LAB in the recovery column was found to be more than 15% and the acid color index (ACI) was 30-35 which sometimes even reached 60.

On study it was concluded that the:
1. Polymerization or chocking of random packing.
2. Excessive pressure drop in packing and Internals.
3. Poor feed distribution because of pipe arm distributor.
4. Wrong elevation of Internals.

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

KEVIN recommended
- Replacement of existing pall ring with hi-performance Medal-Pak tower packings.
- Replacement of existing distributor and re-distributor with high performance distributors & re-distributors to improve the distribution quality.

Accordingly the tower internals and tower packings were manufactured, supplied & installed.

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