Publications

PT Donggi Senoro LNG, a single-train LNG plant, relies on ambient temperature to maintain performance, as it employs air-cooled heat exchangers in propane (C3) and mixed refrigerant (MR) circuits. The changes in ambient temperature led to performance fluctuations, particularly affecting the LPG Reinjection Drum—a two-phase separator collecting heavy hydrocarbons. This drum regulates pressure through three valves: Valve A (to the Low-Pressure Fuel Gas System), Valve B (to the flare), and Valve C (at the inlet).

During low ambient temperatures at night, the C3 refrigerant effectively absorbs heat, minimizing vaporization and keeping Valve B closed. However, at peak temperatures, excessive vaporization occurs, causing 041-PVD-2420B to open and leading to flaring. Additionally, the plant operates at 105-106% of its nameplate capacity due to excess feed gas, further impacting the LPG Reinjection Drum.

To overcome this problem, an initiative is taken to increase the size of Valve A. However, since the plant is a single train, plant availability becomes critical and major modification with long shutdown is not an option. This paper discusses how this fit-for-purpose modification was carried out considering the impact on safe operating parameters, plant layout, effort, and cost. In this case, after evaluating the impact on downstream equipment and consulting with the valve manufacturer, a fit-for-purpose modification can be provided only by changing the trim of the valve. This minor modification does not require purchasing an entire new valve assembly, piping configuration, and containment breaking. Instead, the valve is temporarily removed and only a small internal part of the valve is modified. This minor modification allowed Valve A to handle increased vapor flow, reducing flaring and greenhouse gas emissions while maintaining plant availability and safe operation.