GB2385011A

GB2385011A - Treatment of contaminated gas

Info

Publication number: GB2385011A
Application number: GB0202813A
Authority: GB
Inventors: Terence William Dumbrell; David Gregory Hall; John William Stairmand
Original assignee: Accentus Medical PLC
Current assignee: Accentus Medical PLC
Priority date: 2002-02-07
Filing date: 2002-02-07
Publication date: 2003-08-13
Also published as: WO2003066196A3; AU2003202679A1; WO2003066196A2; GB0202813D0; AU2003202679A8

Abstract

Apparatus comprises contactor 11, connected to receive contaminated air/gas from intake 34 from an apparatus or plant. Contactor 11 comprises vortex chamber 12, which has tangential gas inlet port 13 and axial gas outlet port 14. Liquid feed pipe 15 divides into branches 16, 17, terminating in nozzles 18, 19. Withdrawn liquid is collected in sump 21. Pump 24 drives liquor through pipe 15, forming jets 25. Contaminated air/gas entering chamber 12 is caused to swirl and is thus scrubbed. Contaminants are absorbed by the liquor and carried into sump 21. The scrub liquor is the same as the liquid with which the air/gas comes into contact in apparatus/plant. Decontaminated air is released via outlet 14.

Description

A method of treating'gas The invention relates to the treatment of gas, and in particular air, for removing contaminant from the gas supplied to a plant in which the gas is utilised and comes into contact with liquid.

The invention has particular application to the treatment of air supplied to a gas turbine compressor, for example for power generation. The compressor requires oil lubrication, but requires that the air supply has a very low concentration of volatile organic compounds (VOC's). Such compounds are absorbed in the lubricating oil and cause corrosion of the compressor components. The invention is based upon the appreciation that by pre-scrubbing the air supply to the compressor intake with the same liquid as is used for lubrication of the compressor, then any contaminants, such as VOC's, capable of being absorbed by the liquid will be absorbed in the scrub liquor and thus removed before they can contaminate the lubricant in the compressor. It will be appreciated that this concept is useful for any plant or apparatus in which gas and liquid come into contact and there is a risk that contaminants in the gas when absorbed into the liquid give rise to undesirable effects.

It is an object of the present invention to provide a process for removal of such contamination from a gas or air supplied to a plant or apparatus in which the gas or air comes into contact with a liquid.

According to the invention there is provided a method of treating gas, and in particular air, supplied to a plant or apparatus in which the gas comes into contact with a liquid, which method comprises passing the

gas through a scrubber device in which the gas is scrubbed by a scrub-liquor which is the same as the liquid with which the gas comes into contact in the said plant or apparatus.

Preferably the scrubber device comprises a vortex chamber having at least one tangential inlet port for the gas and an axial outlet port through which the treated gas emerges and, within the chamber, a liquid spray generator which is fed with the said scrub-liquor and which generates a spray of droplets of the scrub-liquor so as to fill a substantial proportion of the vortex chamber with droplets.

Preferably the liquid spray generator is of the type in which opposed jets of liquid impinge upon each other and are disrupted to form a spray of droplets and the liquor is supplied to the liquid spray generator under conditions in which the flow is at least partially turbulent, preferably under conditions for which the Reynolds number is greater than 12,000, so that the droplets in the spray are projected outwardly from, and transverse to the flow direction of, the opposed jets of liquor with a random distribution of the angular relationship between the direction of movement of the droplets relative to the direction of flow of the said opposed jets of liquor.

It may be desirable to cool the scrub-liquor supplied to the scrubber device to improve the absorption by the liquor of contaminants in the gas.

The invention includes a plant or apparatus in which a supply of gas comes into contact with a liquid in the plant, which plant or apparatus includes a scrubber device in which the gas supply is pre-scrubbed by a

scrub-liquor which is the same as the liquid with which the gas comes into contact in the said plant or apparatus.

A method and specific construction of apparatus embodying the invention will now be described by way of example and with reference to the drawing filed herewith which is a diagrammatic cross sectional view of the apparatus.

The apparatus comprises a vortex chamber gas/liquid contactor 11 of the type described in patent GB 2282983.

The contactor 11 is connected to receive air from an air intake 34 and to supply input air, in this example, drawn in by a compressor 36 of a small power supply gas turbine generator.

The contactor 11 comprises a cylindrical vortex chamber 12 which has a tangential gas inlet port 13 and an axial gas outlet port 14. A liquid feed pipe 15, which draws liquid via pump 24 from a supply tank 37, divides into two branches 16 and 17 which enter into the vortex chamber 12 and terminate in two axially opposed nozzles 18 and 19, respectively. The opposed nozzles are, in this example, aligned with the central axis of the vortex chamber 12. A baffle 20 extends across the lower part of the vortex chamber 12 and the portion of the vortex chamber below the baffle 20 forms a sump 21 into which liquor 22 drains from the spray formed in the vortex chamber 12.

In this example, liquor 22 collecting in the sump is removed via outlet 23 and reconstituted, as, for example by distillation, steam stripping, or membrane separation of absorbed contaminants, in equipment indicated

diagrammatically at 38, from which it is returned to the supply tank 37.

Air feed to the tangential inlet 13 of the vortex chamber 12 is supplied by air intake 34 via gas feed pipe 35.

The scrub-liquor drawn from the supply tank 37 is the same liquid as that used for lubrication in the gas turbine compressor 36.

The pump 24 is such as to drive the liquor through the feed pipe 15 and branches 16,17 so that the flow of the opposed liquor jets emerging from the nozzles 18,19 is turbulent, and in this example having a Reynolds number in excess 12,000. Under these conditions, the impinging jets of liquor at 25 are formed into a spray of droplets which are projected in all directions outwardly from, and transverse to the flow direction of, the opposed jets of liquor. Because of the turbulence in the impinging liquor jets, there is a random distribution of the angular relationship between the direction of movement of the droplets relative to the direction of flow of the said opposed jets of liquor. The vortex chamber 12 is, in this way, very effectively filled with droplets of liquor which are collected by their impact on the outer wall of the chamber. The collected droplets flow down the outer wall and into the sump 21, from which this collected liquor is reconstituted in equipment 38 and then available for re-circulation.

The air entering the vortex chamber 12 via the tangential inlet port 13 is caused to swirl through the chamber 12 and ultimately exit axially by outlet port 14.

The air is thus subjected to a particularly effective scrubbing interaction with the spray of droplets of the

liquor. Any contaminants in the air, which are capable of being absorbed by the liquor, are absorbed in the spray droplets and thus carried with them into the sump 21, whilst the air, now significantly decontaminated, flows via outlet 14 into the inlet of the compressor 36.

It may be advantageous to apply a chill to the liquor supplied by the pump 24 to improve the absorption of contaminant gases in the air flowing through the vortex chamber 12. This may be achieved by incorporating a cooler in the tank 37 or in the feed pipe 15.

Further it may be convenient to provide a liquor spray injector (not shown) in the inlet to the compressor 36, as a way of providing, in this example, a supply of uncontaminated lubricating oil to the turbine.

The invention is not restricted to the details of the foregoing example. For instance, there may be circumstances in which it is not air which is supplied but some other gas. The method and apparatus can equally well be applied to the removal from such a gas of contaminants which would otherwise be absorbed in liquid in the process plant with potentially deleterious effects.

The decontamination may require more than 1 stage of treatment in a vortex chamber gas/liquid contactor. Such multiple stage decontamination may readily be applied, for example, by choosing any suitable multiple stage version as described in patent GB 2282983.

Claims

Claims 1. A method of treating air or gas supplied to a plant or apparatus in which the air or gas comes into contact with a liquid, which method comprises passing the air or gas through a scrubber device in which the air or gas is scrubbed by a scrub-liquor which is the same as the liquid with which the air or gas comes into contact in the said plant or apparatus.
2. A method as claimed in claim 1, wherein the scrubber device comprises a vortex chamber having at least one tangential inlet port for the gas and an axial outlet port through which the treated gas emerges and, within the chamber, a liquid spray generator which is fed with the said scrub-liquor and which generates a spray of droplets of the scrub-liquor so as to fill a substantial proportion of the vortex chamber with droplets.
3. A method as claimed in claim 2, wherein the liquid spray generator is of the type in which opposed jets of liquid impinge upon each other and are disrupted to form a spray of droplets and the liquor is supplied to the liquid spray generator under conditions in which the flow is at least partially turbulent, so that the droplets in the spray are projected outwardly from, and transverse to the flow direction of, the opposed jets of liquor with a random distribution of the angular relationship between the direction of movement of the droplets relative to the direction of flow of the said opposed jets of liquor.
4. A method as claimed in claim 3, wherein the liquor is supplied to the liquid spray generator under conditions for which the Reynolds number is greater than 12,000.

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5. A method as claimed in any of the preceding claims, wherein the scrub-liquor supplied to the scrubber device is cooled to improve the absorption by the liquor of contaminants in the gas.
6. A method substantially as hereinbefore described in the example.
7. A plant or apparatus in which a supply of gas comes into contact with a liquid in the plant, which plant or apparatus includes a scrubber device in which the gas supply is pre-scrubbed by a scrub-liquor which is the same as the liquid with which the gas comes into contact in the said plant or apparatus.
8. Apparatus as claimed in claim 7, wherein the liquid spray generator is of the type in which opposed jets of liquid impinge upon each other and are disrupted to form a spray of droplets and means is provided for supplying liquor to the liquid spray generator under conditions in which the flow is at least partially turbulent, so that the droplets in the spray are projected outwardly from, and transverse to the flow direction of, the opposed jets of liquor with a random distribution of the angular relationship between the direction of movement of the droplets relative to the direction of flow of the said opposed jets of liquor.
9. Apparatus as claimed in claim 8, wherein the said means for supplying liquor is adapted to supply liquor to the liquid spray generator under conditions for which the Reynolds number is greater than 12,000.

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10. Apparatus substantially as hereinbefore described with reference to, and illustrated in, the drawing filed herewith.