Increasing Propane Desuperheater and Condenser Reliability in PT Badak NGL

PT Badak NGL is the operator for natural gas liquefaction at Badak LNG Plant, Bontang, Indonesia. At present PT Badak NGL has 8 Trains. The mode for liquefaction is using the APCI process license. At the first step, Feed Gas is pre-cooled with propane refrigerant, followed by liquefaction process by using Multi Component Refrigerant (MCR) as cooler. The MCR is also using propane as its cooler. The propane refrigerant is using three level refrigerant pressures for different level of cooling.

The propane refrigeration system use sea water for condensing the propane after compression. To fulfill this, PT Badak NGL operates 2 parallel propane desuperheaters and 6 parallel propane condensers in each Train. The exchanger acts to condensed propane refrigerant prior being used as cooler media in refrigeration system. The units are all shell and tube exchangers, having sea water stream in the tube side.

The propane desuperheaters and condensers in Train G were frequently facing leakages problem. The last 2 years record showed at least 9 and 5 times repairs have been conducted in the propane desuperheaters and condensers respectively, while other Train's repair frequency only reached below 4 times. The problem has caused significant repair cost and reduction of propane inventory. Our analysis revealed that the sea water stream in the tube side has lower velocity than the minimum required specification of 6 ft/s. This has increased the tendency of fouling in the tube surface. Eventually the fouling effect will promote under deposit corrosion phenomenon which will lead to leakage.

Several options have been proposed for the trouble shooting actions, either by increasing the cooling water supply, installing special tube insert, or by modifying the service mode of the exchangers. PT Badak is planning on implementing the last option to solve the problem since it proposes the least cost of all options. To implement this program, the number of operating propane condensers will be reduced from 6 of 6 service mode to 5 of 6 service mode. This action is expected can increase the sea water velocity thus reducing under deposit corrosion and leakages phenomenon.