INHERENTLY SAFER PROCESS DESIGN FOR VERTICAL KNOCK-OUT DRUMS AND VAPOR/LIQUID SEPARATORS IN GAS PROCESSING

摘要

In gas processing and LNG production, large diameter (> 2 meter) vertical vapor/liquid separator vessels and compressor suction knock-out drums are common. These separate small (<0.1wt%) fraction of flammable liquid from large volumes of gas. The liquid level in these vessels is typically controlled above the bottom tangent line of the vessel permitting storage of large quantity of flammable liquid at the bottom of the vessel, often in excess of the threshold volume for pool fire. To safeguard against hazards of pool fire, such vessels must be designed for fire-depressuring. Piping, adjacent structures and equipment associated with the vessels must also be fireproofed. Inclusion of a small diameter (< 0.5 meter) boot below the bottom of the vessel enables relocation of the level control from the main vessel to the boot. The large liquid inventory in the bottom of the main vessel is removed. The liquid inventory in the boot will be reduced, at least by one order of magnitude to well below the threshold for pool fire, eliminating pool fire potential. This makes the system inherently safer while eliminating costs associated with fire-depressuring and fireproofing.