LIQUID DEGASSING MEANS AND METHOD

Abstract

This invention relates to a liquid degassing means, and method of operation. The means comprises a tank, the tank having one or more baffle(s) within the body of the tank, with at least one baffle defining a first and second region. The first region houses relatively turbulent conditions compared to the second region. There is a both a gas transfer gap and a liquid transfer gap, allowing the transmission of fluid from the first to second regions. An inlet introduced the mixture to be degassed to an antechamber, with the fluid travelling onwards to the first region, and then through the gas and liquid transfer gaps to the second region. A first outlet allows for the degassed liquid to leave the tank, and a second outlet allows for the purged gas mixture to also leave the tank. Sensors and complementary control units allow for better operation of the unit.

Claims

1. Means for degassing a liquid-gas mixture within a system, said means comprising: an enclosed tank to contain a liquid, the liquid having a normal operating level at an intermediate height within the tank, the tank having: one or more baffle(s) within the body of the tank, wherein: at least one of the baffle(s) substantially defines a boundary of a first region and a second region, wherein: the first region accommodates relatively turbulent conditions for the liquid, and the second region accommodates relatively calm conditions for the liquid, wherein there is provided:  a liquid transfer gap for the transfer of liquid from the first region to the second region, and  a gas transfer gap for the transfer of gas from the first region to the second region, an inlet, the inlet being for the introduction of a liquid-gas mixture, and an antechamber, wherein: the inlet enters the antechamber, and the antechamber has an outlet directed towards the first region, the antechamber outlet being above the normal operating level of the liquid, and a first outlet, wherein: the first outlet is adapted for the outflow of the substantially degassed liquid, and the first outlet is situated in the lower half of the tank, substantially below the normal operating level of the liquid and a second outlet, wherein: the second outlet is adapted for the outflow of the gas purged from the liquid-gas mixture, and the second outlet is situated in the upper half of the tank, substantially above the normal operating level of the liquid and means to cause flow of the liquid-gas mixture to the tank, and means to cause flow of substantially degassed liquid from the tank.

2. A tank as claimed in claim 1 wherein a drain outlet is provided

3. A tank as claimed in claim 1 or claim 2 wherein a refill inlet is provided.

4. A tank as claimed in any one of the preceding claims wherein, one or more sensors is coupled with one or more control units to maintain conditions within a range of pre-determined thresholds.

5. A tank as claimed in claim 4 wherein the one or more sensors is any one of, or a combination of: water level sensor, temperature senor, and pressure sensor.

6. A tank as claimed in any one of the preceding claims, wherein a heating element or heat exchanger is provided.

7. A tank as claimed in any one of the preceding claims, wherein a demister is provided at the second outlet.

8. A tank as claimed in any one of the preceding claims, wherein the antechamber is adapted to create turbulent conditions.

9. A tank as claimed in any one of the preceding claims, wherein the antechamber is substantially cylindrical, and the inlet and the outlet of the antechamber are not aligned.

10. A tank as claimed in any one of the preceding claims, wherein the one or more baffles are straight, or curved.

11. A tank as claimed in any one of the preceding claim, wherein the or each baffle is arranged as a shelf within the tank, and at least one baffle abuts the antechamber.

12. A tank as claimed in any preceding claim, wherein a cascade tray is provided between the antechamber outlet and the normal liquid level.

13. A method for degassing a liquid-gas mixture, said method comprising the following steps: providing an enclosed tank for use in a system requiring the degassing of a liquid-gas mixture, the tank being adapted to contain a liquid, the liquid having a normal operating level at an intermediate height within the tank, wherein: one or more baffle(s) in the tank define a first region and a second region, wherein the first region accommodates relatively turbulent conditions for the liquid, and the second region accommodates relatively calm conditions for the liquid, and a liquid transfer gap is present so liquid can transfer from the first region to the second region, and a gas transfer gap is present to allow gas to transfer from the first region to the second region; causing the liquid-gas mixture to flow within the system to the tank through an inlet, the inlet being to an antechamber of the tank, and the antechamber having an outlet which is above the normal operating level of the liquid, flowing the liquid-gas mixture through the antechamber outlet, the liquid-gas mixture then entering the first region, wherein: the liquid-gas mixture cascades into the first region, turbulence in the first region encourages the removal of gas dissolved in the liquid-gas mixture, allowing the substantially degassed liquid to flow from the first region to the second region via the liquid transfer gap, and causing the substantially degassed fluid to flow from the second region through a first outlet for use elsewhere in the system, and removing gas from the tank via a second outlet.

14. A method for degassing a liquid-gas mixture as claimed in claim 13 wherein one or more sensors is used, the sensors being: water level sensors, temperature sensors, and pressure sensors.

15. A method for degassing a liquid-gas mixture as claimed in claim 13 or claim 14, wherein a drain and refill inlet are provided allowing for maintaining the liquid at a desired liquid level, the drain refill inlet being controlled by a control unit, the control unit being adapted to maintain levels within a pre-determined range.

16. A method for degassing a liquid-gas mixture as claimed in any one of claims 13 to 15 wherein a heating element/heat exchanger is provided in combination with a temperature sensor and a control unit for maintaining the temperature of the system.

17. A method for degassing a liquid-gas mixture as claimed in any one of claims 13 to 16 wherein the gas leaving the second outlet is passed through a demister.

Description

[0069] To help with the understanding of the invention, specific embodiments thereof will now be described by way of example and with reference to the accompanying drawings, in which:

[0070] FIG. 1A shows a schematic side view of a first embodiment of a tank in accordance with the present invention,

[0071] FIG. 1B shows a cross sectional view of the tank of FIG. 1A on the line B-B,

[0072] FIG. 2A shows a cross section of a second embodiment of a tank in accordance with the present invention

[0073] FIG. 2B shows a cross section of a tank similar to that of FIG. 2A, but with modifications.

[0074] Referring to FIGS. 1A and 1B, there can be seen the tank 1 with an antechamber 10; the antechamber 10 has an inlet 11 and an outlet 12 which are not aligned. The tank 1 is divided into two regions by a substantially vertical baffle 14. The inlet 11 feeds into the antechamber 10. The inflowing aqueous solution 101 enters the antechamber 10 whereupon turbulent conditions are present. The outflowing aqueous solution 102 exits the antechamber 10 via the outlet 12. From the outlet 12, the aqueous solution falls into the first, relatively turbulent, region to the right of the baffle 14 as shown, because the outlet 12 of the antechamber 10 is well above the normal level 30 of liquid within the tank 1.

[0075] A tray 13 is optional for further agitating the aqueous solution to be de-gassed. The tray may be perforated allowing the solution to flow through, or without any perforations but with a lip such that the tray fills and overflows to cascade below creating more turbulence; in such a case there would be a gap between the tray and a wall of the tank to allow for the fluid to cascade. Any variant thereof could be employed.

[0076] The baffle 14 defines a gas transfer gap and a liquid transfer gap, as denoted by the arrows 103 and 104 respectively. In the second, relatively calm, region (to the left of the baffle 14 as shown), there is a gas outlet 17 for the removal of the gas-vapour mixture, normally to a demister 18. Below the normal liquid level 30, there is an outlet 15, for circulating the substantially degassed liquid in the relevant system 16. Also shown is a refill inlet 19a and a drain 19b for maintaining the desired liquid level 30.

[0077] FIG. 1B shows the preferred cylindrical shape (curvature not to scale) of the antechamber 10, and how the liquid flows 101 in. The cross sectional view is of the relatively turbulent first region, with the relatively calm region being on the other side of the baffle 14 (shown by bolder lines). The arrows 103 and 104 show the liquid and gas travelling from the first region to the second region respectively. Also visible is the cascade tray 13 with a lip.

[0078] In the tank depicted in FIGS. 1A and 1B, the aqueous solution enters the antechamber, preferably with a high velocity. The antechamber is curved such that the solution is forced into turbulent conditions. The solution leaves via the outlet 12 to cascade, via the optional tray 13, to the first region. The turbulent conditions purge the gas, allowing for the gas-vapour mixture to flow 103 via the gas transfer gap to the second region, and out of the tank via the outlet 17 and demister 18. The substantially degassed aqueous solution can travel via the liquid transfer gap 104 to the second region, to flow out to an accompanying system 16 via the outlet 15. This arrangement allows for the aqueous solution flowing to the system 16 to be relatively free of gas bubbles.

[0079] Although sensors and the accompanying control units are not shown, their mode of operation will now be briefly described. Refilling would be triggered when the liquid level dropped below a lower tolerance. The tank would normally then refill until a second pre-determined threshold liquid level was reached. Conversely, the tank could be drained via the drain, should the liquid level become too high, until the level was back within a desired range.

[0080] The temperature can be controlled by a heating element and corresponding thermocouple. Cooling may be done by draining and refilling the system but is preferably performed by a heat exchanger. Heat exchangers, or heat integration systems may be used to improve efficiency.

[0081] Now referring to FIG. 2A, a cross sectional side view of a tank 2 can be seen. In this embodiment, the antechamber 20 is external to the main body of the tank. The aqueous solution flows (as 201) into the antechamber 20 via an inlet 21, and then flows (as 202) into the body of the tank 2. Baffles, which may be in the form of inclined trays 23, with or without perforations, can be seen directing the solution to the second region (which in this case is the lower part of the tank 2), the movement aiding in the degassing of the solution.

[0082] The substantially degassed solution settles and leaves the tank via the outlet 25 to a system 26. The gas-vapour mixture leaves the tank via the outlet 27 and to a demister 28, alternatively, it could be a vent to atmosphere.

[0083] Referring to 2B, a similar tank to the one seen in FIG. 2A can be seen, from a different perspective. The aqueous solution flows in via the antechamber 20 to the first, baffled, region directing the flow downwards to the second settling region. From this second region the aqueous solution leaves via an outlet 25 to flow to the system 26. The gas-vapour mixture would flow to the top counter-currently to the fluyid flow downwards, or alternatively by a direct channel (not shown), to leave by a second outlet 27 to atmosphere or a demister 28.

[0084] For the second embodiment, much like the first, the aqueous solution enters into the tank at a high velocity, via an antechamber 20, to create turbulent conditions in the antechamber 20. The solution exits the antechamber with a relatively decreased velocity, to enter the first region. The baffles 23 of this region help decrease the turbulence, and allow for gas to leave the mixture. As a result, the liquid solution collected at the bottom for circulation to the system is relatively free of gas bubbles, and the gas vapour mixture is relatively dry. A demister 28 may be provided for further separation. A drain 29b and refill inlet 29a are also shown.

[0085] As indicated by the broken line 33 in FIG. 2B the aqueous solution may be recirculated through the system 26 and the tank 2 repeatedly, for example by a pump 34, in a context in which the system 26 introduces a gas into the aqueous solution, and this gas is then removed by passage through the tank 2. The invention is not intended to be limited by the order of the system and pump, or other components constituting the balance of plant. For example the aqueous solution might be a dilute solution of potassium hydroxide (KOH), but any suitable alkaline electrolyte may be used, and the system 26 an electrolysis unit to electrolyse the aqueous solution to generate hydrogen and oxygen gases. The aqueous solution would be recirculated through the tank 2 to remove any remaining gas before the aqueous solution is returned to the electrolysis unit of the system 26. Recirculation of the aqueous solution is equally feasible with the tank 2 of FIG. 2A or the tank 1 of FIGS. 1A and 1B.

[0086] Not shown in the figures are the optional sensors for monitoring temperature and fill level. Nor is there shown a control unit and associated modules shown. The present invention is not intended to be limited to such features. However, such sensors in combination with a control unit and other components allow for monitoring and maintaining conditions within an acceptable range, pre-determined by the user or designer of such a system.

[0087] For any and all embodiments, a plurality of sensors may be employed such as liquid level sensors, temperature sensors, and more. Such sensors would be employed in an expected fashion, and the control systems applied not meriting description herein.

[0088] The removal of dissolved gases is beneficial in the operation of many systems. It can reduce damage to the equipment, help keep the system volume consistent, improve efficiency and more.

[0089] The invention is not intended to be restricted to the details of the above described embodiments. For instance, the arrangements could be combined such as replacing an internal antechamber with an external antechamber, venting to atmosphere as opposed to a demister or equivalent.

[0090] The present invention is not intended to be limited to a material of construction, as a multitude of materials may be suitable, depending upon the physical characteristics of the solution to be circulated. Any number of coatings or varnishes, such as epoxy, may be employed to further increase the longevity of the tank.

[0091] The present invention is not intended to be limited to the designs disclosed in the figures, whilst the baffles are depicted as straight, they could be angled, for example Additionally, many tank shapes may be used in accordance with the present invention, such as cuboid, or cylindrical or something more irregular. A tank in accordance with the present invention may use features from either and any conceivable embodiment.

[0092] The total size of the tank is also not intended as a limitation, neither is the system the liquid degassing means is to be used in. It is envisaged liquid degassing means, and the method of operation thereof will be used in an electrolytic system, but alternative systems may also employ the device and method of use.

[0093] The aqueous solution is require to flow in order for the liquid degassing means to work. The flow of aqueous solution through the system, and through the tank, may involve recirculation. This could be done by any number of pumps or equivalent components, and the invention is not to be limited by such features.

[0094] In the preferred embodiment, the system involves flow of a weak alkaline solution, namely dilute KOH. That said, it is envisaged that a system could require a different solution be it neutral, strongly alkaline, weakly acidic or strongly acidic. The present means and method can be employed to degas any fluid mixture without departing from the spirit of the invention.