| 摘要 |
PURPOSE:To prevent the oxidation of a catalyst over a long period of time, by a method wherein the catalyst in a tower tank is primarily wetted with mineral oil and the surface of the wetted catalyst is secondarily covered with a foam layer before the catalyst is drawn out from the tower tank. CONSTITUTION:A system is substituted with inert gas and the pressure in the system is lowered so as to almost reach atmospheric pressure and the partition valves 6, 9 provided to the outlet piping 5 and tower bottom piping 8 arranged to the upstream and downstream sides of a reactor 7 are closed by blind plates to perform the separation of the reactor 7 from both upstream and downstream sides. Subsequently, the manhole provided to the tower top of the reactor 7 is opened and a foaming apparatus 28 is driven to inject the stock solution in a stock solution storage tank 29 in the reactor 7 in a foamed state through stock solution supply piping 27. By the injection of the stock solution 31 held under a foamed state, a foam layer with a predetermined thickness is formed to the upper surface of the catalyst bed in the reactor 7 and, at this point of time, injection work is completed. |
