Abstract: Dangers of catalyst removal are decreased while the efficiency of the process is increased by provision of a new nozzle. The nozzle is two concentric pipes connected at one end, with the inner pipe extending slightly beyond the outer pipe at the other end. The outer pipe has orifices provided at the connected end which communicate with the exterior of the outer pipe and the space between the inner and outer pipes. A vacuum is pulled on the inner pipe which, in turn, causes gas to enter the space between the inner and outer pipes via the orifices. As the gas sweeps around the end of the inner pipe, it entrains catalyst particles and carries the particles into the inner pipe. The inner pipe extends beyond the reaches of the outer pipe to a distance such that the angle formed between the ends of the inner and outer pipes is approximately equal to the angle of repose of the catalyst.

Abstract: Problems with pressure in a catalyst bed contained within a vessel arise where there is some sort of blockage in the bed such as a crust formed by a layer of catalyst particles sticking together. To overcome this problem control means is provided to coordinate the flow of nitrogen gas into the vessel and the resulting gas pressure build up and maintenance in the catalyst bed and in the bottom of the vessel as well as in the vapor space of the vessel above the catalyst bed.