Initial sealing of cyclone dip-legs

Claim 1

IN THE OPERATION OF A CATALYTIC CONTACT VESSEL ADAPTED TO CONTACT AT AN ELEVATED TEMPERATURE A STREAM OF GAS WITH POWDERED CONTACT MATERIAL NORMALLY MAINTAINED WITHIN SAID VESSEL IN A DENSE FLUID PHASE AND EQUIPPED WITH A CYCLONE SEPARATOR FOR SEPARATING ENTRAINED CONTACT MATERIAL FROM EXIT GAS AND A DIP-LEG EXTENDING FROM SAID SEPARATOR TO A POINT BELOW THE UPPER LEVEL OF SAID DENSE PHASE FOR RETURNING SEPARATED CONTACT MATERIAL TO SAID DENSE PHASE, THE METHOD OF INITIALLY INTRODUCING SAID CONTACT MATERIAL INTO SAID VESSEL WHICH COMPRISES: CLOSING THE LOWER END OF SAID DIP-LEG WITH A CLOSURE ASSEMBLY CONTAINING TEMPERATURE RESPONSIVE MEANS EFFECTIVE AUTOMATICALLY TO OPEN SAID DIP-LEG AT TEMPERATURES IN EXCESS OF A PREDETERMINED MINIMUM, INTRODUCING CONTACT MATERIAL INTO SAID VESSEL AT A TEMPERATURE BELOW SAID PREDETERMINED TEMPERATURE, MAINTAINING THE BULK OF INTRODUCED CONTACT MATERIAL IN DENSE FLUID PHASE BY PASSING A STREAM OF GAS THERETHROUGH, AND AFTER THE LEVEL OF SAID PHASE HAS REACHED THE LOWER END OF SAID DIP-LEG APPLYING SUFFICIENT HEAT TO SAID CONTACT MATERIAL TO CAUSE SAID TEMPERATURE RESPONSIVE MEANS TO OPEN SAID DIP-LEG.