GB2331526A

GB2331526A - A method of deacidifying a gas with a high content of acidic gases

Info

Publication number: GB2331526A
Application number: GB9825073A
Authority: GB
Inventors: Etienne Lebas
Original assignee: IFP Energies Nouvelles IFPEN
Current assignee: IFP Energies Nouvelles IFPEN
Priority date: 1997-11-19
Filing date: 1998-11-17
Publication date: 1999-05-26
Anticipated expiration: 2018-11-17
Also published as: GB9825073D0; DK199801514A; NO985367L; FR2771022B1; AU746323C; AU9243698A; CA2252041A1; NZ332835A; AU746323B2; NO318532B1; GB2331526B; NO985367D0; FR2771022A1

Abstract

A method of deacidifying a gas containing at least one acid gas such as carbon dioxide or hydrogen sulphide and at least one hydrocarbon whereby the acid gas is brought into contact with a liquid solvent phase which is selective towards the acid gas or gases and a temperature gradient is created during this contact treatment to prevent condensation of a liquid hydrocarbon phase and obtain a treated gas with a low content of acid gases and a liquid solvent phase enriched with acid gases. The apparatus used to achieve the removal of the acidic gases involves the use of an absorption tower (C1) where gas at a temperature between 10 and 50‹C is fed in via line (1) to the bottom of the tower and a solvent and water mixture is fed in to the top of the tower via line 2 at a temperature between 0 and -50‹C. Countercurrent flow of the gas through the solvent/water mixture gives purified gas via line (3) and solvent rich in dissolved acidic gases via line (4). A variety of arrangements for the recovery of the solvent phase for subsequent reuse are described (see Figs 3-5, not shown).

Description

2331526 A METHOD OF DEACIDIFYING A GAS WITH A HIGH CONTENT OF ACID GASES

The objective of the present invention is to treat a gas containing at least one hydrocarbon and at least one highly concentrated acid gas with a view to removing at least some of the acid gases contained therein.

The method proposed by the invention is particularly well suited to removing acid from a natural gas.

French patents FR2.605.241 and FR-2.636.857 describe methods of treatment using a cooled physical solvent, which allows the various steps of treating a gas to be performed, one of which is the removal of acid and the removal of water.

These methods have advantages over the techniques of the prior art, in particular the option of using the same polar solvent for both dehydration and deacidification of the gas as well as the possibility of regenerating the solvent by bringing the solvent and the gas to be treated into direct contact with one another in an absorption column (patent FR-2.605.241), which makes for significant savings in terms of energy consumption and financial outlay as well as saving on the space required for equipment.

However, for gases which contain a very high concentration of acid gases, these methods do have 2 their disadvantages. The gas to be treated has to be cooled before it is introduced into the column where the acid gases will be absorbed. This cooling stage causes a very large quantity of hydrocarbons as well as acid gases to condense. This liquid phase has to be stabilised, which means that large quantities of stabilisation gas has to produced and then recompressed and recycled. The presence of this reis a major disadvantage of this involves high capital outlay and compression stage process since it operating costs.

The present invention overcomes the drawbacks of the prior art since it proposes a different approach using an absorption column which operates at a thermal gradient. The gas to be treated is introduced into the absorption column without undergoing pre-cooling, where it is circulated in counter-flow with a cold polar physical solvent.

Advantageously, the way the acid gases are absorbed in the column prevents these acid gases from condensing in a liquid hydrocarbon phase. In fact, the hydrocarbon dew point of the gas at absorption pressure drops sharply as the content of acid gas decreases.

Figure 1 is a temperature (T) and pressure (P) diagram showing two envelope curves A and B, corresponding to the gas to be processed and the treated gas, and giving the corresponding dew points 1 i 3 shown by references a, b.

Line C represents the thermal profile AT which exists in the absorption column, point a, corresponding to operating conditions during the first stage and point b, to those of the final stage.

Figure 1 demonstrates how important the thermal profile of the absorption column is for an example of a given calculation. The changes in the envelope curve of the gas in this column means that a phase of liquid hydrocarbons will not be formed. regardless of stage, the temperature is such that the gas is very far from its hydrocarbon dew point.

Throughout this description, the expression "contact zone,, and the expression "contact device" are is used indiscriminately to refer to the part of the device in which a fluid to be treated is brought into contact with a solvent that has been specially selected to suit acid gases.

Similarly, the expression "rich solvent phase" is used to refer to a solvent phase with a high content of acid gases and "poor solvent phase,, to a solvent phase from which the acid gases have been removed during processing.

The present invention relates to a method of treating a f luid such as a gas containing at least one acid gas and at least one hydrocarbon with a view to removing at least some of the acid gases from said 4 f luid.

It is characterised in that it consists ofat least the following steps:

said gas to be treated is placed in contact inside a contact device with a solvent phase which is selective towards said acid gases, such as a mixture of a polar solvent and water and, simultaneously, a temperature gradient is created inside the contact device in order to prevent condensation of a liquid hydrocarbon phase and produce at the output of the contact device a treated gas which has a low content of acid gases and a solvent gas enriched with acid gases. said temperature gradient being determined as a function of said gas to be treated.

The solvent is a physical polar solvent, for example.

The mixture of solvent and water is fed in counter-flow with the gas to be treated, for example, the gas to be treated being introduced at an initial temperature Tg and the solvent mixture at an initial temperature Tm, the temperature values Tg and Tm being selected so that they will create the requisite gradient inside the contact device and Tg being higher than Tm.

At least a fraction of said gas to be treated can is be drawn off at a temperature level Ti, said fraction of drawn-off gas cooled by means of an exchange of heat with at least a fraction of the treated gas and reinjected at a level below temperature Ti.

At least one fraction of the treated gas from which most of the acid gases have been removed can be used to cool the gas to be treated by circulating said fraction, once it has been drawn off, in counter-flow with said gas to be treated.

The difference in temperature between the head and the base of the absorption column may vary, as an absolute value, between 5 and 150'C and preferably between 30 and 1000C.

The solvent phase enriched with acid gases can be regenerated by simply expanding it.

By using another operating approach, the solvent phase enriched with acid gases can be regenerated by a process of distillation at a pressure lower than the absorption pressure.

At least some of the solvent phase enriched with acid gases can be regenerated by expanding it and bringing it into contact with at least a fraction of the regenerated solvent phase and producing a gas with a controlled content of acid gases.

In another approach to the method, at least some of the solvent phase enriched with acid gases is regenerated by a process of distillation and a 6 simultaneous exchange of heat between said solvent phase which is gradually heated by the solvent phase produced by said regeneration, which is cooled as it circulates in counter-flow with the solvent phase which is regenerated.

Any water that has built up in the solvent phase during the process can be drained off.

The invention also relates to a device for processing a fluid such as a gas containing at least 10 one acid gas It is combination, 1 is and at least one hydrocarbon. characterised in that it consists, in of: at least one delivery line for said gas to be treated, at least one delivery line for a fluid capable of collecting the acid gases, said delivery lines being connected to an enclosure or contact device, said contact device being set up to operate at a temperature gradient across at least a part of the length of the enclosure in order to produce at the output a gas with a low content of acid gases discharged via one line and a solvent phase with a high content of acid gases withdrawn through one line. The contact device may have means for drawing off and re-injecting the fluid and/or gas circulating inside said contact device.

7 is The device has, for example, a circuit which will allow at least some of the water that has accumulated in the fluid used to collect the acid gases to be drained off.

The device and the method described above are used to treat a natural gas containing acid gases such as CO. and/or 142S The invention and its readily understood from the way of illustration only conjunction with the appended f igure 1 shows the curves of characteristics will be more description below, given by and not restrictive, in drawings of which: changes in the envelope a gas in an absorption column with a thermal gradient, figure 2 is an operating diagram of the method proposed by the invention, figures 3 to 5 illustrate embodiments showing different stages which can be used to regenerate the solvent, figures 6 and 7 are diagrams showing examples of how energy can be integrated around the contact device, f igure 8 gives an example of a system that will allow the water which has accumulated in the solvent to be removed, f igure 9 is a diagram showing an example of the method.

8 The principle of the method proposed by the invention will be described in relation to the system illustrated in figure 2, which shows an example of one design for a device applied, as an example, to the 5 treatment applied to a natural gas to deacidify it.

The natural gas to be treated, containing acid gases and at least one hydrocarbon, is fed through line 1 into the absorption column or contact zone Cl where it is brought into contact, in counter-flow for example, with a mixture of solvent and cold water arriving via line 2, the solvent phase containing at least one polar solvent, for example. Inside the contact zone Cl, a given temperature gradient is created to suit the phase diagram of the gas to be is treated (figure 1) so as to prevent a hydrocarbon phase containing acid gases from condensing inside this zone. Within the contact zone, the acid gases are absorbed selectively in the solvent phase.

At the upper part of the contact device Cl, a 20 gaseous phase with a low content of acid gases is discharged via line 3.

At the lower part of the contact zone or contact device Cl, a solvent phase charged with acid gases is drawn off via a line 4.

The temperature gradient is created by introducing the gas to be treated at the bottom of the contact device Cl, for example, at a temperature ranging 9 between 10 and 50'C, and the solvent and water mixture at the head of the contact device at a temperature ranging between 0 and - SO'C.

Advantageously, the f low rate and temperature of the solvent fed in from the head of the absorption column are controlled in order to obtain a desired concentration of acid gas in the treated gas and prevent any condensation of hydrocarbons in the contact device.

The solvent phase leaving the contact device Cl is expanded through the expansion valve V1 and fed to a separating drum Bl which allows it to be separated into a partially regenerated solvent phase which is drawn off at the base via a line 5 and a gaseous phase drawn of f via a line 6 at the top of the drum. This gaseous phase contains co-absorbed acid gases and hydrocarbons. It may possibly be used as fuel gas or recompressed and then recycled to the contact device Cl.

The water content of the solvent phase i 20 preferably at least 1055 as a fraction by volume.

The partially regenerated solvent phase leaving drum Bl via line 5 is expanded through a valve V2 and then delivered to a drum B2 where it is separated into the solvent phase drawn off at the base via a line 7 and the gaseous phase drawn off at the top via a line 8. The solvent phase is expanded through a valve V3 and then sent to a separating drum B3, where it is S separated into a solvent phase drawn of f from the base of the drum via a line 9 and a gaseous phase drawn of f from the head via a line 10.

The gaseous phases discharged through lines 6, 8 and 10 are rich in acid gases.

The solvent phase leaving the drum B3 has a sufficiently low content of acid gases to be recycled to the contact device Cl. Beforehand, it may be necessary to draw of f at least some of the solvent via a line 11 to prevent a build-up of the water brought in through line 1 with the gas to be treated. The remainder of the solvent is then picked up by a PI, mixed with additional solvent line 13 in order to compensate for recycling pump arriving via a solvent losses in the deacidified gas, the acid gases produced and possibly in the drainage line 11 if this latter is not recycled after removing its water content. The resultant mixture flows through a line 14, is cooled in an exchanger EI by means of an auxiliary coolant fluid from outside, for example, and recycled to the contact zone Cl via line 2.

The treatment process proposed by theinvention essentially involves the following steps:

the gas to be treated is brought into contact inside an absorption column with a fluid which is selective towards the acid gases, for example a mixture of polar solvent and water and 11 a temperature gradient is created inside this absorption column so that the acid gases will be absorbed without any hydrocarbons or acid gases condensing or at least if there is any condensation the condensed liquid phase is of a negligible quantity, a treated gas with a low content of acid gases is obtained and a solvent gas with a high content of acid gases. The absorption and the temperature gradient may be obtained by circulating the gas to be treated, introduced from the base of the contact zone at a temperature Tg, in counterflow with the solvent- water mixture, introduced from the top of the column at a temperature Tm where Tm<Tg. The temperature difference ITm-T91 may be within the range between 5 and 1000C.

The value of the pressure prevailing in the absorption column may be between 1 and 20 MPa.

Figure 3 illustrates a different embodiment of the regeneration stage where a distillation column C2 arranged after the drum B1 of figure 2 allows a more advanced regeneration of the solvent phase than that obtained using the layout of figure 2.

The partially regenerated solvent from drum B1 is expanded through the valve V2 and then heated in an exchanger E2 before being fed via a line 20, for 12 example, into the centre of the distillation column C2.

The acid gases produced by distillation are discharged from the head of the column C2 via a line 21, cooled in an exchanger E3 and sent to a decanting or separating drum D1. At the output of this decanting drum, a fraction of the acid gases is discharged via a line 23 and the liquid phase containing the condensed solvent phase is returned via a line 22 to the distillation column C2 where it is used as reflux.

The regenerated solvent phase is drawn off from the base of the distillation column C2 vA-a a line 24, cooled in an exchanger E2 before being fed through a line 25 to the draining line 11 and the recycling pump P1 using a layout as described in connection with figure 2.

Figure 4 illustrates another embodiment of the device of figure 3 in which the separating drum B1 has a contact zone, the purpose of which is to control the acid gas specification for the gaseous flow drawn off by line 6.

To this end, a fraction of the solvent phase which has been regenerated and recycled as illustrated in figure 3 is drawn off and sent through a line 26 located at the head of the contact zone 27 of the drum Bl.

Inside this contact zone 27, some of the acid gases are absorbed with the aid of a given quantity of 13 solvent to obtain in line 6 a gaseous effluent with a controlled content of acid gases, selected to suit a desired specification.

Figure 5 illustrates another method of reregenerating the solvent. The exchanger E2 of figure 3 is replaced by a stripper exchanger ES1, which performs a distillation and simultaneous heat exchange between the rich solvent phase introduced via line 7 on a level with the top part of the stripper exchanger ES1, which is gradually heated, and the solvent phase from the regeneration stage fed into the lower part via line 24 from the distillation column C2 and which is cooled by being circulated in counter-flow with the solvent phase which is regenerated.

At the output of the stripper exchanger ES1, a rich solvent is obtained at the base and sent via line 20 to the distillation column C2 and a rich gas at the head fed via a line 28 and at the upper part of the column the regenerated solvent phase drawn off via a line 29 linked to the recycling pump Pi.

The internal heat exchange between the solvent phase rich in acid gases and the solvent phase poor in acid gases described above may be obtained using other devices.

The integrated exchanger ES1 may be of the shell and tube type. This being the case, the re-generated solvent phase drawn off from the base of the column C2 is 1 1 14 circulates inside the tubes and distillation takes place on the exterior of the tubes and inside the shell.

Alternatively, the exchanger stripper ES1 may be a plate exchanger, in which case the tubes will be placed above each plate so as to be immersed in the rich solvent phase to be recovered which circulates across each plate.

The exchanger stripper ES1 may be a continuous- contact exchanger, in which case the rich solvent phase will trickle across the tubes.

The regenerated solvent phase drawn off from the base of the column C2 may also circulate on the exterior of the tubes and inside the shell.

Distillation will then take place inside the tubes, which by preference will be positioned vertically and provided with an interior packing.

It is also possible to use an exchanger with vertical plates for the absorption columns and/or stripper exchanger described in relation to the abovementioned drawings. The spaces between the different plates may alternately be occupied by the regenerated solvent phase drawn of f form the base of the column C2 and the solvent phase and vapour phase generated as during circulation through the column in counter-flow during the distillation process. It may be an exchanger of the brazed aluminium type, for example, or stainless steel, the plates being either butt-welded or welded by metal diffusion across the entire contact surface between plates.

Figure 6 illustrates an example of the absorption stage in which the cold treated gas is used to cool at least to a certain degree the gas to be treated as it circulates in the absorption column. The gas is drawn off, during treatment, on a level with a plate of the column Cl or between two packing zones of the column Cl via a line 30, cooled in an exchanger E4 by the treated gas discharged through line 3 and then fed back into the column C2 via a line 31. The drawing-off and injection levels as well as the number thereof along the column will be chosen so as to optimise the is recovery of cooling capacity of the treated gas recovered in line 3.

Figure 7 shows another embodiment of the absorption stage in which there is a simultaneous exchange of heat between the treated gas which is heated gradually and the gas to be treated brought in contact with the solvent, which is cooled as it circulates in counter-flow. This type of heat exchanger can be set up using devices other than those described above in connection with figure 5.

The treated gas leaving the absorption column Cl via line 3 is returned by this same line to the head of the column, where it circulates in counter-flow with 1 I 1 16 the gas introduced from the base of the column via line 1. After exchanging cooling capacity with the gas to be treated, it leaves, heated, via a line 33, located at the base of the column, for example.

The gas to be treated may contain water in different forms and in some situations it may be necessary to remove this water to prevent it from building up in the solvent phase.

Figure 8 shows a draining system which allows any water that has built up in the solvent phase during processing to be removed and consists of a contact device C3 positioned downstream of the thermal gradient contact device Cl.

The raw gas to be treated is split into two fractions and sent respectively to lines 35 and 36.

A first fraction is fed through line 36 which rejoins line 1 (figure 1) delivering the gas into the contact device Cl.

The second fraction of gas to be treated is fed via line 35 into the bottom part of the contact device C3.

The solvent phase charged with water from the draining line 11 (figure 1) is fed into the head of the contact device C3 by means of a pump P2 and a line 34.

At the output of the contact device C3, a gas charged with solvent is discharged from the head via a line 38 communicating with the delivery line 1 and an 17 aqueous phase containing virtually no solvent which is discharged from the base of the contact device via a line 37.

The present invention will be more readily understood from an example, which is not restrictive, of a gas treatment process described below.

This example, described in connection with figure 9, is a system for deacidifying a natural gas with a very high content of CO, The natural gas to be treated is, f or example, of the following composition, given in % by moles:

NITROGEN 1.20 is CARBON DIOXIDE HYDROGEN SULPHIDE METHANE ETHANE PROPANE ISOBUTANE BUTANE ISOPENTANE PENTANE HEXANE This gas is saturated witl of 300C and a pressure of 7MPa.

70.50 0.21 27.64 0.24 0.10 0.02 0.02 0.01 0.01 0.03 water at a temperature Its molar flow rate is 22400 kmol/h. This gas is split into two fractions in lines 35 and 36. The gas in line 35 is fed into the contact device C3 at a molar flow rate of 17000 kmol/h.

1 18 Injected in counter-flow via line 34 is a solvent fraction containing approximately 6 kmol/h of water and 54 kmol/h of methanol. At the base of the contact device C3, a flow of 17 kmol/h of water containing approximately 200 molar ppm of methanol is drawn off via line 37.

The gas f rom, the head of the contact device C3, charged with methanol, is mixed with the gas in line 36 then the recycled gas from the regenerating drum B1 through a line 40. It is then fed into the contact device Cl. At the head of solvent is injected in approximately 5500 kmol/h of methanol at a temperature conditions, the contact device Cl is operated with a thermal gradient of 230C at the base to -230C at the the contact device Cl, a via line 2 containing water and 49500 kmol/h of of -300C. Under these head. The treated gas is drawn off from the head of the contact device Cl via line 3. It has a f low rate of 6603 kmol/h and contains approximately 8796 by moles of methane and 8% by moles of C02. This gas is heated in the exchanger E to a temperature of SOOC, before being discharged via a line 41.

The rich solvent is drawn off from the contact device Cl via line 4. It is expanded to a pressure of 3.5 MPa through valve V1. At the output of the separating drum Bl, a solvent phase is drawn off via line 5 and a gaseous phase is discharged via line 6.

19 The gaseous phase containing approximately 6800 kmol/h of C02 and 1300 kmol/h of methane is compressed to 7 MPa by a compressor K and then cooled to 3CC by an exchanger E to be recycled to the base of the contact device Cl via line 40.

The solvent in line 5 is expanded to a pressure of 1 MPa through valve V2, separated in the drum B2 into a gaseous phase drawn off via line 8 and a solvent phase drawn off via line 7. The gas in line 8 has a flow rate of 10153 kmol/h and a concentration of 95% by moles of C02 The solvent is again expanded to a pressure of 0.2 MPa through valve V3, separated in the drum B3 into a gaseous phase drawn off via line 10 and a solvent phase drawn off via line 9. The gas in line 10 has a flow rate of 5666 kmol/h and a concentration of 98.52k by mole of C02 A solvent fraction is drawn off via the draining line 11 and sent to the pump P2 to be injected into the contact device C3 via line 34. The other solvent fraction is sent to the pump P1 and cooled to -30C in the exchanger El before being fed into the contact device Cl via line 2.

The method allows the acid gases contained in a natural gas to be removed as well as those contained in a refinery gas or any gaseous effluent simultaneously containing hydrocarbons and acid gases. It may be used to remove acid gases such as H.S and CO, as well as mercaptans of a chemical formula R-SH, COS and CS..

The different steps of the method proposed by the invention can be carried out in columns provided with a contact zone allowing a mass transfer between the gas phases and the liquid phases. To this end, these contact zones may be fitted with perforated trays, bubble-cap trays or valve trays or they may have continuous contact zones containing a packing. This packing may consist of bulk elements such as, for example, Raschig rings, Pall rings, Berl saddles or any other packing known to the person skilled in the art. It may also consist of stacked packing made of gauze, knitted fabric or sheets which may be perforated or corrugated and/or forming channels, which will increase efficiency. These trays or packings may be made from various materials such as ceramic, aluminium, stainless steel or plastic. 20 The fluid which is selective towards the acid gases may be a polar solvent chosen from methanol, an alcohol, an ether, a polyethylene glycol ether, propylene carbonate. Without departing from the scope of the invention, it would also be possible to use a solvent made up of two polar solvents or alternatively a polar solvent and an amine.

is

Claims

21 CLAIMS

1 - A method of treating a fluid such as a gas containing at least one acid gas and at least one hydrocarbon with a view to removing at least some of the acid gases from said fluid, characterised in that it consists of at least the following steps:

said gas to be treated is brought into contact with a phase which is selective towards said acid gas or gases, such as a mixture of polar solvent and water and, simultaneously, a temperature gradient is created in order to prevent condensation of a liquid hydrocarbon phase and obtain a treated gas with a low content of acid gases and a solvent phase rich in acid gases, said temperature gradient being determined as a function of the gas to be treated.

2 - A method as claimed in claim 1, characterised in that the solvent and water mixture is fed in counter- f low with the gas to be treated, the gas to be treated being introduced at an initial temperature Tg and the solvent mixture at an initial temperature Tm, the temperature values Tg and Tm being chosen so as to crate the requisite temperature gradient inside the contact device and Tg being higher than Tm.

A method as claimed in one of claims 1 or 2, 22 characterised in that at least a fraction of said gas to be treated is drawn of f at a temperature level Ti, said drawn-off gas fraction is cooled by an exchange of heat with at least one fraction of the treated gas and 5 then re-injected at a temperature level lower than Ti.

1 4 - A method as claimed in one of claims 1 or 2, characterised in that at least a fraction of the treated gas from which the majority of acid gases have been removed is used to cool the gas to be treated by circulating said drawn-off fraction in counter-flow with said gas to be treated.

- A method as claimed in one of claims 1 to 4, characterised in that a temperature difference is created inside the contact device varying, in terms 'of absolute value, between 5 and ISO'C and preferably between 30 and 1OCC.

6 - A method as claimed in one of claims 1 to 5, characterised in that the solvent phase enriched with acid gases is regenerated by a simple process of expansion.

7 - A method as claimed in one of claims 1 to 5, characterised in that the solvent phase enriched with acid gases is regenerated by a process of distillation 23 at a pressure below the absorption pressure.

8 - A method as claimed in one of claims 1 to 5, characterised in that at least some of the solvent phase enriched with acid gases is regenerated by expanding it and placing it in contact with at least one fraction of regenerated solvent phase and producing a gas with a controlled content of acid gases.

9 - A method as claimed in one of claims 1 to 5, characterised in that at least some of the solvent phase enriched with acid gases is regenerated by a process of distillation with simultaneous heat exchange between said solvent phase which is gradually heated by the solvent phase produced at the end of said is cooled as it circulates in the solvent flow which is regeneration which counter-flow with regenerated.

10 - A method as claimed in one of the claims, characterised in that any water that has built up in the solvent phase during the process is drained off.

11 - A device for treating a fluid such as a gas containing at least one acid gas and at least one hydrocarbon consisting of at least one delivery line (1) for said gas to be treated and at least one delivery line (2) for a fluid capable of collecting the g i -1 1 i 24 acid gases, characterised in that said delivery lines (1) and (2) are linked to an enclosure (Cl) or contact device, said contact device being designed to operate with a temperature gradient across at least a part of the length of the enclosure (C1) to produce at the output a gas with a low content of acid gases discharged via a line (3) and a solvent phase enriched with acid gases drawn off via a line (4).

12 - A device as claimed in claim 11, characterised in that said contact device has means for drawing off and means for re-injecting the fluid and/or gas circulating inside said contact device.

13 - A device as claimed in claim 11, characterised in that it has a circuit (11, C3) which enables at least some of the water that has built up in the fluid capable of collecting the acid gases to be drained off.

14 - Use of the method as claimed in one of claims 1 to 10 and the device as claimed in one of claims 11 to 13 to treat a natural gas containing acid gases such as CO, and/or H2S ' 15. A method of treating a fluid substantially as hereinbefore described with reference to the accompanying drawings.

16. A device for treating a fluid substantiallyas hereinbefore described with reference to the accompanying drawings.