Location: Heilongjiang, China

Start-up time: 2009

Background:

There were many problems since the unit ran due to original design deficiency of internals in benzene column, which were high pressure drop, column flooded, unsteady operation and low capacity and tray efficiency. The purposes of this reconstruction were as following:

(1) To decrease overall column pressure drop of benzene column to be less than 0.1 MPa in order to eliminate column flooded;

(2) To increase capacity of unit, improve mass transfer and reduce energy consumption;

(3) To make pressure and temperature of benzene column stable.

Solution:

The process was simulated according to basic data supplied by customer in order to perform hydraulic calculation. The results showed that trays #1-#32 of benzene column were already flooded because original internals design were not reasonable. Hence, ZEHUA put forward the following specific plans for revamping:

(1) All internals for trays #1-#32 should be replaced, except for support rings. New design internals were based on increasing DC area and open area so as to decrease pressure drop and increase capacity.

(2) All internals for trays #33-#100 could be remained without any modification.

Result:

(1) Overall column pressure drop of benzene column was 0.07MPa;

(2) Temperature distribution of benzene column was significantly improved;

(3) 99.1 percent of products from benzene column, much higher than before reconstruction, could meet quality controlling standard;

(4) Not only could Capacity meet the requirement but also reflux ratio was less than design value.