Vertical purification device

A gas purification device including two adsorbers, each having a lower portion and an upper portion, a gas compressor, a heater, a set of exchangers, a first assembly of pipework and valves, and a second assembly of pipework and valves, wherein the first assembly of pipework and valves is located on the floor or on a metal structure proximate to the lower portion, and the second assembly of pipework and valves is located high up along the same vertical axis as the first assembly of pipework and valves proximate to the upper portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 371 of International PCT Application No. PCT/FR2016/052649, filed Oct. 13, 2016, which claims priority to French Patent Application No. 1559847, filed Oct. 16, 2015, the entire contents of which are incorporated herein by reference.

BACKGROUND

The present invention relates to a device for purifying a gas comprising two adsorbers and a particular arrangement of pipework.

Separation devices of this type are essentially used in pressure swing adsorption (PSA) or temperature swing adsorption (TSA) technologies for the production, from a gaseous mixture, of a gaseous constituent of this mixture, in particular of a constituent of air, oxygen or nitrogen, or for the purification of a gaseous mixture, in particular feed air of a cryogenic air separation unit, also for the production of a constituent of air, oxygen and/or nitrogen and/or argon and generally use at least one of the adsorbents selected from the group comprising zeolites, activated carbon, alumina or silica gels. Examples of these technologies are described in particular in documents U.S. Pat. No. 5,223,004, EP 0 092 153, U.S. Pat. Nos. 3,338,030 or 5,137,548.

Purifications, or a purification device, in air separation units (ASUs) make it possible to mainly remove water and CO2from the air before entry into the cryogenic cold box.

An assembly of valves and pipework enables the transit of the air (to be purified) and of the impure nitrogen (which is used for the regeneration of the purification cylinders) and that connects the lower and upper parts of the cylinders to the various fluid circuits.

Generally, the assembly of valves and pipework is laid “flat” on the floor in front of or between the purification cylinders and the cross-sectional area of this assembly occupies a very large floor space in relation to the cross-sectional areas of the purification cylinders, a floor space factor ranging from 1.5 to 3.5 for ASUs respectively having a capacity of 1000 t/day O2to 5000 t/day O2.

In small to medium capacity (<1000 t/day O2) air separation units, this assembly may be mounted on a metal frame, except for the purification cylinders and the coupling pipework, in order to limit the work on site. The metal frame comprising the various elements supported thereby is generally referred to as a “skid”.

FIG. 1represents a purification device. Typically, a purification device comprises a first adsorber1, a second adsorber2, an assembly of valves and pipework3laid on the floor or on a skid. This purification device is connected to an air compressor4, a regeneration heater5, an exchanger cold box6.

The layout of the pipework is complex especially due to the difference in levels of the interfaces of the assembly of valves and pipework with the other piece of equipment (adsorbers, exchangers, etc.) and these were large amount of pipes and bends.

Indeed, the distances CC1; DD1; EF; F1G1are proportional to the height of the cylinders and of the exchangers relative to the assembly of valves and pipework which is itself on the floor. By way of example, for a device treating an air flow rate of around 300,000 Nm3/h, these distances represent respectively 18 m for CC1and F1G1, 19 m for DD1and 21 m for EF for a pipework diameter of 40 inches, i.e. 1 m.

This arrangement leads to a large amount of pipes and bends linked to this layout which consequently leads to pressure drops in the process. 0.5 mbar per m of additional pipework and 2.5 mbar per additional bend can be considered.

Starting from here, one problem that is faced is that of providing a purification device that has a smaller amount of pipework.

SUMMARY

One solution to the present invention is a gas purification device comprising two adsorbers1and2, a gas compressor4, a heater5, a set of exchangers6, a first assembly of pipework and valves10and a second assembly of pipework and valves11, characterized in that the first assembly of pipework and valves10is laid on the floor or on a metal structure and the second assembly of pipework and valves11is located high up along the same vertical axis as the first assembly of pipework and valves10.

The expression “located high up” is understood to mean that the center of gravity of the second assembly of pipework and valves is located approximately (i.e. to within plus or minus 15%) in the same horizontal axis as the product gas outlet point of at least one adsorber.

DESCRIPTION OF PREFERRED EMBODIMENTS

Depending on the case, the location device according to the invention may have one or other of the following characteristics:

the second assembly of pipework and valves11is supported with the aid of a set of supports resting at least partially on the first assembly of pipework and valves10;

the set of supports is a metal structure;

the second assembly of pipework and valves11is supported directly by the first assembly of pipework and valves10;

the first and second assemblies of pipework and valves10and11rest on a metal frame enabling the handling thereof;

the second assembly of pipework and valves11is supported with the aid of a set of supports resting at least partially on one of the two adsorbers;

in each pipework-valve assembly, the diameter of the pipework is less than 1200 mm, preferably less than 1000 mm, more preferentially still less than 800 mm;

the heater5is supported by the second assembly of pipework and valves11;

the valves of the first and second assemblies of pipework and valves10and11are positioned on the facade or on the roof;

the first and second assemblies of pipework and valves10and11comprise one or more pieces of equipment chosen from check valves, measurement instruments, and pressure regulators, with said pieces of equipment positioned on the facade or on the roof;

the set of exchangers6is a cold box of cryogenic exchangers.

For the piece of equipment positioned “on the facade” (check valves, valves, measurement instruments, pressure regulators, etc.), it is understood that the pieces of equipment are positioned facing the user so that he/she can easily gain access thereto. For the piece of equipment positioned “on the roof”, it is understood that the pieces of equipment are positioned facing upwards so that they can be accessible with a lifting appliance (crane, lift truck, etc.).

The objective of the present invention is to divide the assembly of valves and pipework into two sub-assemblies of reduced size that are installed one above the other and that thus reduce the distances CC1; DD1; EF; F1G1when referring toFIG. 1.

The present invention will now be described in greater detail with the aid ofFIG. 2.

The purification device comprises two adsorbers1and2, two superimposed sub-assemblies of valves and pipework10and11, where10is laid on the floor, and11supported by means of a set of supports resting on10. This purification device is connected to a gas compressor4, a regeneration heater5, a set of exchangers6.

Pipework15external to the pipework-valve sub-assemblies10and11may be attached to the device and optionally be supported by one or more elements of the device. The assembly of this external pipework15will in general be carried out on the construction site.

The device according to the invention enables the reduction in the installation cost of the purification device by reducing the overall amount of length of pipework.

By way of example, for a system treating an air flow rate of 300,000 Nm3/h, the reduction in length of pipework is of the order of 40% and the reduction in the amount of welds is of the order of 15%.

Moreover, dividing the assembly of valves and pipework3into two makes it possible, for the same capacity, to reduce the size of the2sub-assemblies of valves and pipework10and11and to thus envisage the prefabrication thereof on a skid with the advantage of limiting the constraints linked to the transport size.

Furthermore, the device according to the invention makes it possible to significantly reduce the installation times by limiting the construction activities on site to only the connections of the pipework15owing to its high degree of prefabrication on a skid.

Finally, as can be seen inFIG. 3, the device according to the invention occupies a smaller floor space than that which an identical device of conventional design laid on the floor would occupy,FIG. 4.

By way of example, for a system treating an air flow rate of 300,000 Nm3/h, the floor area and the civil engineering slab for installing all the pieces of equipment of the purification device is reduced by the order of 51%. The floor space factor of the two sub-assemblies of valves and pipework in relation to the sizes of these purification cylinders is 1.85.

Finally, another subject of the present invention is the use of a purification device according to the invention for producing oxygen from an air flow. In this case, the adsorbers of the purification device will have the main role of removing water and CO2from the air flow before entry into the cold box of cryogenic exchangers.

Another subject of the invention is the use of the purification device according to the invention for producing carbon monoxide from synthesis gas.