Hello All,
I am trying to understand the working of a vapor balance system when filling LPG from mounded bullets to trucks. I have two scenarios and associated questions:
1. When I pump liquid LPG from bullet to a truck using pumps, my understanding is that initially pressure will rise in the truck until vapor pressure is sufficient to overcome friction losses etc. and reach back to tank. For e.g. lets say liquid LPG arrives at truck at 140 psig, and pressure inside truck is 90 psig (vapor pressure @ ambient), then pressure in the truck will rise and when it overcomes friction losses to go back to bullet, it will stay the same. Is this what will normally happen ?
2. Now I have a case where the truck is connected to a vapor header. The vapor header is simultaneously being used for vapor return and another operation wherein the compressor is putting vapor into that header. Hence the vapor header is at high pressure. Now because truck vapor space is connected to this header...what happens inside the truck? for e.g. vapor header is at say 200 psig, truck vapor space is initially at 90 psig (vap pr. at ambient)...I assume for vapor to go back to header, it has to be above 200 psig? would that be possible...pump makes the liquid lpg reach the truck at 140 psig...what will happen in such a case??