coil leak the high pressure cold propane as the working fluid in the vent condenser 310 can leak into the depropanizer column 240 rather than the alkylation catalyst leaking into the one or more cooling coils 320 hence the alkylation catalyst typically hydrogen fluoride cannot contaminate the wet gas or fuel systems moreover a leak can be detected quickly and fixed by monitoring the refrigerant level in the one or more cooling coils 320 or a surge drum 330 the line 322 can communicate with the surge drum 330 the refrigerant can pass through a line 324 to a pump 340 which can pump the refrigerant up to a pressure of about 1 900 kpa afterwards the refrigerant can pass through a line 326 to the exchanger 360 chilling can be provided by vaporizing the same or different refrigerant typically a liquefied petroleum gas stream 364 at a pressure of about 300 about 500 kpa and a temperature of about u2212 5 about 5 u00b0 c can be provided to cool the vaporized refrigerant after exiting the exchanger 360 the refrigerant can be at a temperature of no more than about 20 u00b0 c preferably below about 0 u00b0 c the refrigerant may return to the.