Capacity including at least two vertical particle beds, of which at least one bed can be drained alone.

Abstract

Storage capacity comprising at least two vertically separated particle beds (AA, MS), the capacity comprising: - a first particle bed (AA) and a second particle bed (MS), - at least one grid (5, 15) separating the first bed (AA) from the second bed (MS), the grid (5, 15) being configured to maintain a vertical separation between the first bed and the second bed (AA, MS), - a fabric (7, 17) extending in support of the grid (5, 15) and configured to prevent the migration of particles from the first bed (AA) to the second bed (MS), - a drain orifice (3, 13) arranged for the evacuation of the second bed (MS) from the capacity, - characterized in that the fabric (7, 17) is arranged between the first bed (AA) and the grid (5, 15). (Abstract figure: Fig. 1)

Description

Title of the invention: Capacity comprising at least two vertical particle beds, of which at least one bed is drainable on its own.

[0001] The invention relates to the field of gas treatment and concerns a storage capacity comprising at least two vertically separated particle beds, the capacity comprising: - a first particle bed and a second particle bed, - at least one grid separating the first bed from the second bed, the grid being configured to maintain a vertical separation between the first and second beds, - a fabric extending in support of the grid and configured to prevent the migration of particles from the first bed to the second bed, - a drain opening arranged for the evacuation of the second bed out of the capacity, - characterized in that the canvas is arranged between the first bed and the grid.

[0002] Due to the position of the fabric in the container according to the invention, between the first bed and the grid, it is possible to empty the second bed without having to empty the first bed, as the particles in the first bed are held in place by the fabric, which rests against the grid. Maintaining the fabric in a vertical position is not contingent upon the presence of the second bed in the container.

[0003] Since the first bed, in a first embodiment, is not intended to be drained, the cloth is held in position between the grid and the first bed. Thus, the grid also prevents the migration of particles from the second bed to the first bed.

[0004] The first particle bed and the second particle bed comprise particles of an adsorbent or catalyst material, for example agglomerates.

[0005] According to one embodiment, the grid includes openings of characteristic dimension equal to 3cm.

[0006] According to one embodiment, the mesh comprises openings of characteristic size that are a function of the characteristic size of the particles in the first and second beds (for example, the openings are an order of magnitude smaller than the particles), typically with a characteristic size of 3 mm. The mesh is typically a metal mesh, comprising openings having such a characteristic size. Here, the term "mesh" is given a very general meaning defining a flexible material, for example, made of interlaced threads, having free passages allowing the circulation of a fluid, more particularly the circulation of a gas. The mesh will preferably be formed from a fabric, having regular openings. The meshes cover a fairly wide range with threads whose diameter The size can range from a millimeter to a few tens of microns, with the majority being between 0.5 and 40 microns. The opening (void) is generally between several millimeters and a hundred microns. The void ratio, meanwhile, ranges from 20 to 80%, most frequently from 30 to 70%.

[0007] The web can be welded along its periphery to the grid or can be fixed along its periphery to the grid by other means. For example, rods are fixed to the grid and pass through the web, with washers threaded onto the rods holding the web in place.

[0008] The capacity includes an envelope delimiting a gas circulation space, said space comprising the first and second bed.

[0009] The separating grid divides the gas flow space into two volumes: a first volume containing the first bed and a second volume containing the second bed. The drain orifice is located on the side of the second volume. The grid is arranged to prevent the migration of particles from the first bed to the second volume, while allowing the gas to flow freely from the first volume to the second volume. Such particle migration could otherwise occur when the first volume is filled with particles from the first bed, without the second volume being filled.

[0010] The envelope is for example of parallelepiped shape, the gases passing from a first side of the parallelepiped through the first bed, then the second bed, to a second side of the parallelepiped opposite the first side.

[0011] The envelope can also be cylindrical with a vertical axis, in which the gas flow is radial. The first volume is, for example, an annular volume furthest from the axis of the cylinder and surrounding the second volume, the second volume being closest to the axis. The gases then flow from the first volume to the second volume and are discharged through a central volume centered on the axis of the cylinder. It should be noted that the first volume can, conversely, be the volume closest to the axis of the cylinder and the second volume the volume furthest from the axis, the gas flow then being reversed, from the central volume towards the outside of the cylinder.

[0012] The first bed comprises, for example, particles of an adsorbent such as alumina or silica gel. The first bed typically serves to remove impurities from the feed gas. The second bed comprises, for example, particles of a molecular sieve-type adsorbent, such as 13X. The unit is then an adsorber.

[0013] An impurity may, despite the passage of gases through the first bed, reach the second bed and contaminate it. The adsorbent of the second bed may, in some cases can hardly be regenerated in situ, which may require evacuating the second bed for replacement or regeneration outside the capacity.

[0014] The drain port is, for example, located above the second bed. Draining is then carried out from the top of the tank by suction, and filling with the replacement bed or the regenerated bed is also done from the top.

[0015] It is possible to optimize the capacity according to the invention. Thus, according to a second embodiment, the fabric is a first fabric, and the capacity includes a second fabric extending in support of the grid and configured to prevent the migration of particles from the second bed to the first bed, the second fabric being arranged between the second bed and the grid. The capacity may then include, in addition to the drain orifice (being a first drain orifice), a second drain orifice arranged for the evacuation of the first bed from the capacity. It then becomes possible to drain the first bed without having to drain the second bed, the particles of the second bed being held in place by the second fabric, which is supported against the grid. Maintaining the second fabric in a vertical position is not contingent upon the presence of the first bed in the capacity.

[0016] The capacity according to the invention can be implemented for the removal of contaminants such as water, CO2, NOx, hydrocarbons, and other trace impurities from a feed gas by a pressure- and / or temperature-modulated adsorption process, prior to further treatment, such as cryogenic air separation. The first bed is typically used to remove impurities such as water or CO2. The second bed can be used to remove CO2, propane, N2O, or other hydrocarbons.

[0017] The invention also relates to a method of emptying a capacity such as described above, comprising emptying the second bed, without emptying the first bed.

[0018] The invention is applicable to any storage capacity in which different layers of particles are to be separated vertically while allowing a fluid to flow freely through these different layers. It can be implemented in a reactor containing at least two vertical catalyst beds or an adsorber containing at least two vertical adsorbent beds, the adsorber being used in any gas separation process by pressure- or temperature-modulated adsorption.

[0019] The invention can in particular be implemented for the vertical separation of more than two particle beds from each other.

[0020] [Fig. 1] [Fig. 1] is a schematic representation of a first embodiment according to the invention; and

[0021] [Fig.2] [Fig.2] is a schematic representation of a second embodiment according to the invention.

[0022] Figure 1 shows a first bed of alumina AA and a second bed of molecular sieve MS, AA and MS being contained between two walls 1, 2 of a parallelepiped-shaped container. Figure 1 is shown in a cross-section of the parallelepiped-shaped container. The other walls of the container's shell are not shown for simplification. The upper wall 2 includes a first discharge port 3 for the MS bed and a second discharge port 4 for the AA bed. An intermediate grid 5 separates the AA bed from the MS bed and maintains these two beds in a vertical position. Two so-called lateral grids 6, each combined with a mesh (not shown) extending between the lateral grid and the bed in question, maintain the AA and MS beds in a vertical position on their sides opposite the intermediate grid 5. An intermediate mesh 7 rests on the intermediate grid 5 and prevents the migration of particles from the AA bed to the MS bed.The canvas 7 extends between bed AA and bed MS, thus allowing bed MS to be drained without draining bed AA.

[0023] Figure 2 represents an embodiment of the cylindrical vessel according to the invention with radial gas flow. Figure 2 is shown in a cross-section of the cylindrical vessel. A first bed of alumina AA and a second bed of molecular sieve MS, AA, and MS are contained between two lower and upper disc-shaped walls 11, 12 of the cylinder. The other walls of the vessel's shell are not shown for simplicity. The upper wall 12 includes two drainage ports 13 for the MS bed and two drainage ports 14 for the AA bed. An intermediate cylindrical grid 15 separates the AA bed from the MS bed and maintains these two beds in a vertical position. Two so-called lateral grids 16, also cylindrical in shape, each combined with a mesh (not shown) extending between the lateral grid and the bed in question, maintain the AA and MS beds in a vertical position on their sides opposite the intermediate grid 15.An intermediate mesh 17 extends cylindrically, resting on the intermediate grid 15, and prevents the migration of particles from the AA bed to the MS bed. The mesh 17 extends between the AA bed and the MS bed, thus allowing the MS bed to be emptied without emptying the AA bed.

Claims

Demands

1. A storage capacity comprising at least two vertically separated particle beds (AA, MS), the capacity comprising: - a first particle bed (AA) and a second particle bed (MS), - at least one grid (5, 15) separating the first bed (AA) from the second bed (MS), the grid (5, 15) being configured to maintain a vertical separation between the first bed and the second bed (AA, MS), - a fabric (7, 17) extending in support of the grid (5, 15) and configured to prevent the migration of particles from the first bed (AA) to the second bed (MS), - a drain orifice (3, 13) arranged for the evacuation of the second bed (MS) from the capacity, - an enclosure delimiting a gas circulation space, said space comprising the first and second beds (AA, MS), - characterized in that the fabric (7, 17) is arranged between the first bed (AA) and the grid (5, 15).

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