Commissioned in October 2021, the Ammonia Emissions Management System (AEMS) for Ballance Kapuni was a significant milestone for PGL. Spanning almost 3-years, the project involved the design and retrofit of a flare system with 40+ relief devices into the Ballance Kapuni ammonia plant.
For Ballance, the driver for the project was to improve operator and community safety for their plant. From Process Group's perspective, this was certainly a landmark project of great complexity for flare system design. This included unique relieving combinations of toxicity, very hot, very cold, cooling water flooding mitigation, subsonic ammonia combustion through to high velocity syn gas / hydrogen combustion.
A critical design requirement of the new flare system was to prevent the flare system flooding with cooling water, in the event that rupture discs on cooling water exchangers burst (either inadvertently due to fatigue/cooling water pump pressure surge or due to heat exchanger tube leak/ break).
Cooling water ingress into the flare system is prevented by the Liquid Knock Out Drum (LKOD). The LKOD is a special two compartment vessel configuration designed by PGL with the first compartment providing cooling water holdup for the cooling water heat exchangers and the second compartment acting as a conventional Flare Knock Out Drum (FKOD) for all relief sources connected to the flare system.
The combination of extreme cold (-60°C) and the presence of water in the first compartment also posed liquid level indication challenges due to freezing. This was mitigated by configuring the level transmitter bridle with nozzle connections to the LKOD at multiple heights.
The in-plant location of the 45m high integral flare seal drum / stack required detailed Phast analysis of flare radiation profiles and ammonia toxicity contours for the unlit flare scenario. The in-plant location of the flare was made possible by PGL developing a solution to limit the ultimate flare load and hence the radiation profile on the plant. The maximum flare load is caused by blocked outlet at the Ammonia Converter of the three synthesis loop recycle compressors.
This scenario was able to be eliminated as the ultimate sizing case for the flare system by installing a bypass Rupture Pin Valve (RPV) around the Converter. This allows the recycle compressors to continue circulating - the developed overpressure is then significantly reduced being only due to the Ammonia Converter being bypassed and the lesser synthesis gas makeup flow to the loop continuing.