The sweetened LPG exits the tower .
The sweetened LPG flows through : a caustic settler vessel to remove any entrained caustic , a water wash vessel to further remove any residual entrained caustic and a vessel containing a bed of rock salt to remove any entrained water .
The sweetened LPG exits the tower and flows through : a caustic settler vessel to remove any entrained caustic , a water wash vessel to further remove any residual entrained caustic and a vessel containing a bed of rock salt to remove any entrained water .