We are facing rapid chocking problem of our feed bottom exchangers of sour water feed/stripped water. In last maintenance, tube side of these exchagers (Sour Water) there were found amonium salts deposited in form of lumps, that ultimately traveld through tower and back in the shell of these exchangers. These have cuased serious flow restrictions at stripped water pump due to insufficent suction. To examine this phenomena suction straniner of feed pump were opened but found almost clean. That shows nothing is coming from the feed tank. Please guide upon possible cause of this salt built up in shell and tube type feed bottom exhangers.