I N TEM P ERATU RE SWI NG ADSORPTION SYSTE M

Technical field of the present invention

The present invention relates to an apparatus and to a method for cryogenic separation processes; more particularly, the present invention relates to an apparatus and to a method for purifying a fluid, in particular for removing impurities from the fluid, in a temperature swing adsorption (TSA) system.

Background of the present invention

During a cryogenic process, often operated within a "cold box", a purification step occurs upstream of the cryogenic process for removal of carbon dioxide (C0 ₂ ), of water (H ₂ 0) and/or of methanol

(CH ₃ OH, often as MeOH) to a level less than 0.1 parts per million (ppm).

The remaining content of impurities downstream of the temperature swing adsorption (TSA) vessels permits an operation of the cryogenic process for about two to three years, before the process has to be stopped in order to remove trapped impurities by a deriming process.

Referring to FIG.1, there is shown a purification process by a temperature swing adsorption (TSA) for removing carbon dioxide (C0 ₂ ), water (H ₂ 0) and/or methanol (CH ₃ OH, often as MeOH). Such a process provides for purification to a level less than 0.1 ppm as installed upstream of the cold box CB for a cryogenic process.

The purification process presents a problem for operators, wherein the cryogenic separation process must be continuous or "onstream" for a period greater than three years and up to as much as five years before removal of trapped impurities from the process is to occur.

In other words, some projects require the onstream time of the process to be operational for more than about two to three years (= standard onstream time of the cryogenic separation process) but for up to five years. Therefore, what is needed is a purification process downstream of the TSA for further removal of impurities so that the cryogenic separation process can operate for as long as up to five years before removal of trapped impurities (by deriming) is necessary.

Disclosure of the present invention: object, solution, advantages

Starting from the disadvantages and shortcomings as described above and taking the prior art as discussed into account, an object of the present invention is to increase the onstream time for cryogenic separation processes. This object is accomplished by an apparatus comprising the features of claim 1 , by a method comprising the features of claim 1 1 as well as by a system comprising the features of claim 15. Advantageous embodiments and expedient improvements of the present invention are disclosed in the respective dependent claims.

According to the present invention, there is therefore provided an increased onstream time for cryogenic separation processes by an apparatus as well as by a method for purifying a fluid, in particular for removing impurities from the fluid, in a temperature swing adsorption (TSA) system, said apparatus comprising at least one chemisorption guard bed.

According to an advantageous embodiment of the present invention, the chemisorption guard bed may be disposed upstream of at least one cold box; in this context, the chemisorption guard bed may be disposed between and in fluid communication with the TSA system and the cold box in order to remove impurities from the fluid.

With the TSA system expediently comprising at least one first adsorption vessel and at least one second adsorption vessel, said adsorption vessels or temperature swing adsorption (TSA) vessels may favourably be disposed upstream of the cold box. According to a preferred embodiment of the present invention, the chemisorption guard, in particular being embodied as at least one chemisorption layer, may be disposed in at least one of the first adsorption vessel and/or of the second adsorption vessel, and in particular may be proximate a bottom of at least one of the first adsorption vessel and/or of the second adsorption vessel. Alternatively thereto, the chemisorption guard bed may advantageously be disposed in at least one separate vessel downstream of the first and second adsorption vessels.

In order to provide for provide for ultrapurification of the fluid, the chemisorption guard bed may expediently comprise an actuated alumina adsorbent.

The present invention finally relates to a temperature swing adsorption (TSA) system comprising at least one apparatus as described above and/or working according to the method as described above.

Brief description of the drawings

For a more complete understanding of the present inventive embodiment disclosures and as already discussed above, there are several options to embody as well as to improve the teaching of the present invention in an advantageous manner. To this aim, the present invention is described in more detail below; in particular, reference may be made to the claims dependent on claim 1 as well as dependent on claim 1 1 ; further improvements, features and advantages of the present invention are explained below in more detail with reference to a preferred embodiment by way of non-limiting example and to the accompanying drawings taken at least partly in connection with the following description of the embodiments, of which:

FIG. 1 shows a schematic drawing of a known temperature swing adsorption (TSA) system upstream of a cold box for a cryogenic process;

FIG. 2 shows a schematic drawing of a first embodiment of an apparatus according to the present invention, said apparatus working according to the method of the present invention; and

FIG. 3 shows a schematic drawing of a second embodiment of an apparatus according to the present invention, said apparatus working according to the method of the present invention.

In the appended drawing figures, like equipment is labelled with the same reference numerals throughout the description of FIG. 1 to FIG. 3.

Detailed description of the drawings; best way of embodying the present invention

Before describing the present inventive embodiments in detail, it is to be understood that the inventive embodiments are not limited in their application to the details of construction and arrangement of parts illustrated in the accompanying drawing figure, since the present invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

The present invention will be described with reference to the drawing figures.

The apparatus embodiments of FIG. 2 and of FIG. 3 provide for ultrapurification within or downstream of the TSA apparatus 10 and upstream of the cold box 12 for further removal of impurities below the level of 0.1 ppm and in certain instances, down to a level of parts per billion (ppb), for example for carbon dioxide (C0 ₂ ) less than thirty ppb, by chemisorption in order to achieve an increased onstream time for the cryogenic separation process.

Referring to the embodiment of FIG. 2, a chemisorption guard bed 14 is positioned in a separate vessel 16 downstream of the TSA vessels 1 1 and upstream of the cold box 12 as shown. The elements of the embodiment of FIG. 2 are indicated by reference numeral E1.

In FIG. 3, a chemisorption layer 18 is disposed proximate a bottom 20 of one or both of the adsorber vessels 1 1 in the TSA. The elements of the embodiment of FIG. 3 are indicated by reference numeral E2. There is therefore provided herein for a temperature swing adsorption (TSA) apparatus having a cold box 12, an apparatus for purifying a fluid including a chemisorption guard bed 14 disposed between and in fluid communication with the TSA system and the cold box 12 for removing impurities from the fluid. The chemisorption guard bed 14 may be disposed upstream of the cold box 12.

There is also provided herein for a temperature swing adsorption (TSA) system having first and second adsorption vessels 1 1 , and a cold box 12, an improvement including a chemisorption guard bed 18 disposed in at least one of the first and second vessels 1 1. The first and second adsorption vessels 1 1 may be disposed upstream of the cold box 12.

Valves 22 are provided as indicated for the various streams, although not all are indicated by reference numerals.

Ultrapurification is considered to be accomplished with an activated alumina adsorbent in the chemisorption guard bed 14 or 18.

The arrangement of this apparatus with respect to the existing system can be provided with or without a regeneration mode. That is, without a regeneration mode, a guard bed has to be disposed; while having the regeneration mode permits the guard bed to be designed for an extended onstream time (for example one month to two months), after which it has to be regenerated.

Regeneration is with nitrogen (N ₂ ) at elevated temperatures (approximately 270°C) by use of high pressure steam or electrical heater. Either the regeneration system of the existing TSA is used and designed accordingly, or a separate regeneration system for the guard beds has to be installed and operated.

Run time for the chemisorption step can be lower than the required cryogenic separation run time by bypass operation for replacement of chemisorption filling or a second guard bed. In the situation where the chemisorption layer is integrated in the TSA vessels, the adsorbent exchange can be managed by a three-adsorber system.

It will be understood that the embodiments described herein are merely exemplary, and that one skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as described and claimed herein. Further, all embodiments disclosed are not necessarily in the alternative, as various embodiments of the invention may be combined to provide the desired result.

List of reference numerals 10 temperature swing adsorption (TSA) apparatus or temperature swing adsorption (TSA) system

1 1 adsorber vessel or temperature swing adsorption (TSA) vessel

12 cold box

14 chemisorption guard bed

16 vessel

18 chemisorption guard bed or chemisorption layer

20 bottom of adsorber vessel 1 1

22 valve

CB cold box (cf. FIG. 1 : example from prior art)

E1 first embodiment (cf. FIG. 2)

E2 second embodiment (cf. FIG. 3)

PCS process condensate separator (cf. FIG. 1 : example from prior art)

PGA process gas absorber (cf. FIG. 1 : example from prior art)

PGF process gas filter (cf. FIG. 1 : example from prior art)

RG regeneration gas (cf. FIG. 1 : example from prior art)

RGC regeneration gas cooler (cf. FIG. 1 : example from prior art)

RGH regeneration gas heater (cf. FIG. 1 : example from prior art)

RGS regeneration gas separator (cf. FIG. 1 : example from prior art)

SC1 first syngas cooler (cf. FIG. 1 : example from prior art)

SC2 second syngas cooler (cf. FIG. 1 : example from prior art)

SG syngas (cf. FIG. 1 : example from prior art)

TSA temperature swing adsorption (apparatus or system) (cf. FIG. 1 : example from prior art)