Capacity comprising at least two vertical particulate beds, including at least one bed that can be drained alone.

Abstract

Storage capacity comprising at least two particulate beds (AA, MS) separated vertically, the capacity comprising:- a first particulate bed (AA) and a second particulate 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 abutment on 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 particulate beds, at least one of which can be drained alone.

[0001] The invention belongs to the field of gas treatment and relates to a storage capacity comprising at least two vertically separated particulate beds, the capacity comprising: - a first particulate bed and a second particulate 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 bed and the second bed, - a fabric extending in support on the grid and configured to prevent the migration of particles from the first bed to the second bed, - a drain orifice arranged for the evacuation of the second bed from 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 capacity 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, the particles of the first bed being held in place by the fabric which is pressed against the grid. Maintaining the fabric in a vertical position is not conditioned by the presence of the second bed in the capacity.

[0003] Since, in a first embodiment, the first bed is not intended to be emptied, the fabric 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 particulate bed and the second particulate bed comprise particles of an adsorbent or catalyst material, for example agglomerates.

[0005] According to one embodiment, the grid comprises openings with a characteristic dimension equal to 3 cm.

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

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

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

[0009] The separating grid delimits the gas circulation space into two volumes, a first volume comprising the first bed and a second volume comprising the second bed. The drain orifice is arranged on the side of the second volume. The screen is arranged to prevent the migration of particles from the first bed to the second volume, while allowing the gases to flow freely from the first volume to the second volume. Such migration of particles could otherwise occur when filling the first volume 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 may also be cylindrical with a vertical axis, in which the circulation of gases occurs radially. 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 circulate from the first volume to the second volume and are evacuated by a central volume centered on the axis of the cylinder. It will be noted that the first volume may, on the contrary, be the volume closest to the axis of the cylinder and the second volume be the volume furthest from the axis, the circulation of gases then being reversed, starting 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 is typically used to remove impurities from the feed gas. The second bed comprises, for example, particles of a molecular sieve type adsorbent, such as 13X. The capacity is then an adsorber.

[0013] An impurity may, despite the passage of gases through the first bed, reach the second bed and pollute it. The adsorbent of the second bed may in certain cases difficult to regenerate in situ, which may require evacuating the second bed for replacement or regeneration outside the capacity.

[0014] The drain orifice is for example located above the second bed. Draining is then carried out from the top of the capacity, by suction and filling with the replacement bed or the regenerated bed is also carried out 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 comprises a second fabric extending in abutment on 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 can then comprise, 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 in abutment against the grid. Maintaining the second fabric in a vertical position is not conditioned by the presence of the first bed in the capacity.

[0016] The capacity according to the invention can be implemented for the removal from a feed gas of contaminants such as water, CO2, NOx, hydrocarbons and other trace impurities by a pressure and / or temperature swing 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 as described above, comprising emptying the second bed, without emptying the first bed.

[0018] The invention is applicable to any storage capacity in which it is desired to vertically separate different layers of particles while allowing a fluid to circulate 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, adsorber implemented in any process for separating gases by pressure or temperature modulated adsorption.

[0019] The invention can be implemented in particular for the vertical separation of more than two particulate 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] [Fig. 1] represents a first bed of alumina AA and a second bed of molecular sieve MS, AA and MS being included between two walls 1, 2 of a parallelepiped-shaped capacity. [Fig. 1] is placed in a sectional plane of the parallelepiped capacity. The other walls of the envelope of the capacity are not shown for simplification. The upper wall 2 comprises a first orifice 3 for emptying the MS bed and a second orifice 4 for emptying 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 cloth (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 cloth 7 extends in support on the intermediate grid 5 and prevents the migration of particles from the AA bed to the MS bed.The web 7 extends between the AA bed and the MS bed, thus allowing the MS bed to be drained without draining the AA bed.

[0023] [Fig. 2] represents an embodiment of the capacity according to the invention of cylindrical shape with radial circulation of the gases. [Fig. 2] is placed in a sectional plane of the cylindrical capacity. A first bed of alumina AA and a second bed of molecular sieve MS, AA and MS are included between two lower and upper disc-shaped walls 11, 12 of the cylinder. The other walls of the envelope of the capacity are not shown for simplification. The upper wall 12 comprises two orifices 13 for draining the MS bed and two orifices 14 for draining the AA bed. An intermediate grid of cylindrical shape 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 of cylindrical shape, each combined with a cloth (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 emptied the AA bed.

Claims

Claims

1. Storage capacity comprising at least two particulate beds (AA, MS) separated vertically, the capacity comprising: - a first particulate bed (AA) and a second particulate 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 abutment on 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 envelope 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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