The present invention relates to vacuum apparatus, and in particular to vacuum apparatus suitable for removing compacted particulate material (such as spent catalyst) from a containing vessel (such as a reactor).

It is known to use elongate pipes connected to vacuum suction units to remove spent particulate catalyst material from reactor vessels or the like. It is similarly known to use screw auger feeders to transport such material from the interior of the reactor to a suction hose located on the exterior of the vessel.

Both of the above-mentioned techniques involve insertion of the pipe or screw auger into the bed of material via a port or manway in the side of the containing vessel.

Use of the first mentioned apparatus requires considerable operator skill to maintain an optimum air gap between the tip of the suction pipe and the bed of the catalyst material (which is often compacted) with the result that when the length of insertion of the pipe into the vessel is too long, material flow stops due to lack of conveying gas flow.

Use of the second mentioned apparatus has the significant disadvantage that on insertion of the rotating screw auger into the bed, spillage of the particulate catalyst material (which is hazardous to health and environment) often occurs. Furthermore, the screw auger apparatus has a tendency to jam, often causing failure, which then necessitates personnel entry into the hazardous environment of the container vessel.

Improved vacuum apparatus has now been devised which alleviates many of the above-mentioned difficulties with prior art apparatus.

According to a first aspect of the invention, there is provided vacuum apparatus comprising an elongate pipe defining a bore extending along the length thereof, the proximal end of the pipe being connectable with suction means arranged to transport particulate material along the bore from a distal end of the pipe toward the proximal end, the apparatus being provided with jetting means arranged to direct a plurality of pressurised fluid jets into the bore in the region of the distal end of the pipe.

It is preferred that the plurality of pressurised jets are directed into the bore defined by the pipe transversely to the longitudinal direction of the pipe. Advantageously, the pressurised jets are directed radially inwardly into the bore.

Typically, the jetting means comprises a plurality of jetting apertures communicating through the inner bore-defining surface of the pipe in the region distal end of the pipe. Advantageously, the jetting apertures communicate between the bore of the pipe and a chamber defined by inner and outer surfaces of the pipe.

Advantageously, the chamber is provided with a substantially closed end defined by the distal end of the pipe. Where the pipe and bore are substantially cylindrical, the chamber will typically be substantially annular.

The jetting means is connectable to a supply of pressurised fluid. Typically, the jetting means is supplied with a pressurised gas which may be pressurised air or nitrogen.

Advantageously, the supply of pressurised fluid is connectable (usually by means of a connection port) to the apparatus in the region of the proximal end of the pipe. Typically a fluid supply conduit or path is provided extending between the proximal and distal ends of the pipe and communicatively connecting the jetting means and the supply of pressurised fluid.

The fluid supply conduit or path is preferably provided outside the bore defined by the pipe.

It is preferred that the fluid supply conduit or path extends along the pipe intermediately adjacent the inner and outer surfaces of the pipe. Advantageously, the fluid supply conduit or path comprises a relatively narrow bore defined in the material of the piping extending along the pipe intermediately adjacent the inner and outer surfaces of the pipe.

The pipe is preferably constructed principally of metallic material. Alternatively a hard wearing plastics material may be utilised.

Typically, the transverse exterior dimensions of the pipe will be such that the pipe may be conveniently inserted into a manway or port of an industrial reactor containing particulate catalyst material.

According to a second aspect of the invention, there is provided a method of removing particulate catalyst material or other particulate material from a container vessel, which method comprises inserting into the particulate material contained in the vessel the distal end of a pipe comprising apparatus as defined in relation to the first aspect of the invention, directing a plurality of fluid jets into the bore of the pipe in the region of the distal end to cause agitation of the particulate material, and causing suction of the agitated particulate material along the pipe from the distal end thereof towards the proximal end.

The invention will now be further described in a specific embodiment by way of example only, and with reference to the accompanying drawings, in which

Figure 1 is a schematic perspective view of vacuum apparatus according to the invention; and

Figure 2 is a diagrammatic view of the apparatus of Figure 1 in use.

Referring to the drawings, the vacuum apparatus, generally designated 1, comprises an elongate cylindrical pipe 2 arranged to be connected at a proximal end 3 thereof to a flexible suction hose 4 which is itself connected to a filter unit and vacuum pump arrangement (not shown).

The major proportion of the length of the pipe 2 comprises a substantially solid cylindrical pipe wall 8 (typically of metal or plastics construction) defining a central cylindrical bore for the pipe. Proximate the distal end 5 of the pipe 2, the inner and outer walls of the pipe define an annular chamber 6 which is closed at the distal end 5 of the pipe 2. The inner cylindrical wall of chamber 6 is provided with a plurality of apertures 7 communicating between the annular chamber 6 and the bore of the pipe 2.

A narrow communication bore 9 extends longitudinally of the pipe 2 through the substantially solid cylindrical pipe wall 8 between a communication port 10 with annular chamber 6, and an inlet port 11 at the proximal end of pipe 2. Inlet port 11 is connected via flexible pipe 12 to a supply of pressurised gas (typically air or nitrogen).

In use, vacuum pipe 2 is inserted into a bed of catalyst 13 at the base of a reactor 14 via a side port or manway 15 as shown in Figure 2. Prior to insertion, the vacuum pump connected to suction hose 4 is activated so as to draw transported particulate

catalyst 7 material along the pipe 2 and into suction hose 4. At this stage, the pressurised gas supply to inlet port 11 is also activated, thereby forcing pressurised gas long narrow communication bore 9 and into chamber 6 at the distal end 5 of pipe 2. The pressurised gas is then forced out of apertures 7 (which act as jets or nozzles) into the interior of pipe 2.

The portion of the bore of pipe 2 defined by annular chamber 6 acts as a fluidising core in which compacted particulate catalyst present in the fluidising core, or directly adjacent the distal end 5 of pipe 2 on insertion of the pipe 2 into the bed, is fluidised under the influence of the jetting pressurised gas passing through apertures 7. This produces a volume of fluidised particulate catalyst material at the distal end 5 of the pipe 2 which is then sucked along pipe 2 towards the proximal end 3 of pipe 2, and subsequently along flexible suction hose 4 to the filler unit and vacuum pump arrangement (not shown). Using vacuum apparatus according to the present invention, it is possible to insert the vacuum pipe all the way to the rear of the compacted catalyst bed without substantial loss of material conveying efficiently. Furthermore on insertion of the pipe 2 into reactor 14 via manway 15 there is substantially no spillage as would be the case with prior art air powered screw auger type conveyors.

Additionally, operator judgement required to achieve an optimum air gap between the compacted catalyst bed and the end of conventional vacuum pipe conveyors is eliminated by the presence in use of the fluidised core. The problem of inability to convey material when the length of insertion into the bed of conventional vacuum pipes exceeds a limiting distance is also alleviated since a supply of transport gas is effectively continually supplied to the distal end 5 of the pipe.