WO2018085892A1

WO2018085892A1 - Modular system for gassing and degassing liquids

Info

Publication number: WO2018085892A1
Application number: PCT/AU2017/051234
Authority: WO
Inventors: Lee Carty
Original assignee: Pti Pacific Pty Ltd
Current assignee: Pti Pacific Pty Ltd
Priority date: 2016-11-11
Filing date: 2017-11-10
Publication date: 2018-05-17
Anticipated expiration: 2019-05-11

Abstract

A modular system for gassing and degassing liquids, comprising a core module (2) having a membrane contactor (8) and gas and liquid inlets (14, 10) and outlets (16, 12). When configured for gassing (4): the gas inlet line (24) is connected to the gas inlet port of the membrane contactor having pressure and flow sensors (26, 28); a liquid feed pump (30) is connected in the liquid input line (18) having pressure and flow sensors (32, 34); and a controller is connected to said sensors and pump. When switched to degassing (6) mode the configuration is: a vacuum pump (38) is connected in the gas outlet line (36) from the gas outlet port of the membrane contactor having a pressure sensor (40); and a controller is connected to said sensor and pump.

Description

MODULAR SYSTEM FOR GASSING AND DEGASSING LIQUIDS

Field

[0001 ] The present invention relates to a modular system for gassing and degassing liquids.

Background

[0002] Conventional methods for gassing liquids, such as injecting gas into liquid within pressurised tanks or into a liquid stream, require low temperatures. For example, effective carbonation typically requires the beverage to be maintained below 4°C to achieve sufficient diffusion of carbon dioxide (C0₂) into the beverage, and an increase of just a few degrees can significantly impact carbonation levels. This typically requires refrigeration of the entire fluid stream even if the fluid is cold at input, since the fluid heats up as it is pumped through the apparatus. Conventional gassing systems accordingly require bulky and expensive infrastructure, and energy-intensive processes.

[0003] Conventional methods for degassing liquids involve heating the liquid to expel gases, or installing large vacuum towers which can be expensive and require a large footprint in a plant or factory. For medical grade sterilisation, European standard EN 285 requires that the volume of non-condensable gases (NCG) in the sterilisation steam is less than 3.5%. If the steam contains too much NCG, the gases can form bubbles or insulation layers on downstream equipment, such it takes longer for the sterilisation steam to penetrate through the gas layers and directly contact the surface of the equipment to be sterilised, hence reducing the sterilisation efficiency. Conventional means for removing NCG from process water include heating the water to above 80 °C to force the gas out of the liquid. Conventional means of monitoring and verifying that sufficient NCG has been removed include offline sampling and condensing of the steam, to compare volumes before and after the condensation. As will be appreciated, these conventional methods are energy-intensive, inefficient, potentially hazardous to the user and do not allow real time monitoring, testing and adjustment of the process. [0004] Additionally, the effectiveness and rate of gas transfer depends on multiple factors including temperature of the liquid, surface contact time between the gas and liquid, pressure of the gas input, liquid and gas flow rates, etc. It is challenging to control these multiple, interdependent variables to obtain consistent and repeatable results.

[0005] In many applications, both gassing and degassing steps are required. For example, during a brewing process, brewing water or water added back to high- gravity beer must first be de-aerated to remove oxygen which is detrimental to the shelf-life and freshness of the beverage. The beverage is subsequently carbonated, or degassing may instead be required to reduce carbonation levels in an over- carbonated product (for example, due to fermentation). Accordingly, a disadvantage of prior art methods is the inability to quickly and easily modify process according to changing requirements, products lines, etc.

[0006] In this context, there is a need for an improved system for gassing and/or degassing liquids.

Summary

[0007] According to the present invention, there is provided a modular system for gassing and degassing liquids, comprising:

a core module connected to a gassing module and/or a degassing module; wherein the core module comprises:

a membrane contactor comprising a liquid inlet port, a liquid outlet port, a gas inlet port, and a gas outlet port;

a liquid inlet line connected to the liquid inlet port of the membrane contactor;

a liquid outlet line connected to the liquid outlet port of the membrane contactor; and

a controller;

wherein the gassing module comprises:

a gas inlet line connected to the gas inlet port of the membrane contactor; a gas inlet pressure sensor and a gas inlet flow sensor connected in the gas inlet line, and connected to the controller;

a liquid feed pump connected in the liquid input line, and connected to the controller; and

a liquid inlet pressure sensor and a liquid inlet flow sensor connected in the liquid input line, and connected to the controller; and/or

wherein the degassing module comprises:

a gas outlet line connected to the gas outlet port of the membrane contactor;

a vacuum pump connected in the gas outlet line, and connected to the controller; and

a gas outlet pressure sensor connected in the gas outlet line, and connected to the controller.

[0008] The core module may further comprise a particulate filter connected in the liquid inlet line upstream of the liquid inlet port of the membrane contactor.

[0009] The core module may further comprise a pre-filter pressure sensor connected in the liquid inlet line upstream of the particulate filter, and a post-filter pressure sensor connected in the liquid inlet line downstream of the particulate filter, wherein the pre-filter pressure sensor and the post-filter pressure sensor are each connected to the controller.

[0010] The degassing module may further comprise a pre-membrane gas concentration sensor connected in the liquid inlet line upstream of the contactor membrane, and a post-membrane gas concentration sensor connected in the liquid outlet line downstream of the contactor membrane, wherein the pre-membrane gas concentration sensor and the post-membrane gas concentration sensor are each connected to the controller.

[001 1 ] The gassing module and/or the degassing module may further comprise a gas sweep connected to the gas outlet port of the membrane contactor. [0012] The gassing module may further comprise a liquid inlet temperature sensor connected in the liquid inlet line upstream of the contactor membrane, and a liquid outlet pressure sensor connected in the liquid outlet line downstream of the contactor membrane, wherein the liquid inlet temperature sensor and the liquid outlet pressure sensor are each connected to the controller.

[0013] The liquid feed pump may comprise a sanitary or industrial centrifugal pump.

[0014] The gassing module may further comprise a valve upstream of the liquid feed pump, wherein upon detection of a threshold high pressure and/or threshold low flow and/or threshold high temperature in the liquid inlet line, the controller is configured to close the valve to suspend liquid input to the pump.

[0015] The system may comprise both the gassing module and the degassing module, wherein operation of the system is switched between gassing and degassing modes by controlling operation of the vacuum pump.

[0016] In gassing mode, the vacuum pump may be configured to evacuate gas condensate from the membrane contactor when the system is in standby.

[0017] Gassing may be performed at up to approximately 25 °C.

[0018] In degassing mode, the vacuum pump may be activated to evacuate gas transferred from the liquid to the gas within the membrane contactor. It can be used in conjunction with a degassing carrier gas to specifically remove particular gases such as oxygen, nitrogen and/or carbon dioxide.

Brief Description of Drawings

[0019] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a schematic illustration of one embodiment of the modular system for gassing and degassing liquids; and

Figure 2 is a schematic illustration of a second embodiment of the modular system for gassing and degassing liquids.

Description of Embodiments

[0020] Referring to the drawings, the modular system 1 according to one embodiment comprises a core module 2 connected to a gassing module 4 and/or a degassing module 6. The core module 2 may comprise a controller (not shown) and a membrane contactor 8 having a liquid inlet port 10, a liquid outlet port 1 2, a gas inlet port 14, and a gas outlet port 16. Liquid inlet line 1 8 is connected to the liquid inlet port 10 of the membrane contactor, and liquid outlet line 20 is connected to the liquid outlet port 12 of the membrane contactor. Membrane contactor 8 comprises a porous, hydrophobic membrane element (not shown) separating a liquid flow path and a gas flow path within the membrane contactor. Gas is transferred into or out of the liquid flow path through the membrane element, depending on the difference in partial pressure of the gas in each flow path.

[0021 ] The gassing module 4 may comprise a gas inlet line 24 connected to the gas inlet port 14 of the membrane contactor 8, a gas inlet pressure sensor 26 and a gas inlet flow sensor 28 each connected in the gas inlet line 24, a liquid feed pump 30 connected in the liquid input line 18, and a liquid inlet pressure sensor 34 and a liquid inlet flow sensor 32 each connected in the liquid input line 18. The sensors 26, 28, 32, 34 capture operational parameters of the liquid and/or gas lines. A manual or automatic gas pressure regulator (not shown) may also be connected in the gas inlet line 24. The sensors 26, 28, 32, 34 and the liquid feed pump 30 may each be connected to the controller.

[0022] Referring to Figure 2, which illustrates an embodiment comprising both the gassing module 4 and the degassing module 6, the degassing module may comprise a gas outlet line 36 connected to the gas outlet port 16 of the membrane contactor 8, a vacuum pump 38 connected in the gas outlet line 36, and a gas outlet pressure sensor 40 connected in the gas outlet line 36. A moisture removal filter (not shown) and an automated pressure regulator (not shown) may also be connected in the gas outlet line 36. The vacuum pump 38 and the gas outlet pressure sensor 40 may each be connected to the controller.

[0023] The controller receives data from the sensors and transmits control signals to the liquid feed pump 30 and/or vacuum pump 38, in response to the sensed operational parameters of the liquid and/or gas lines. In preferred embodiments, the programmed response of the controller is additionally based on user input, preset control variables, calculations according to feedback and control algorithms, or combinations thereof. The controller may comprise means for receiving user input, eg via a screen, buttons, switches, or remotely via a computer, mobile phone, etc.

[0024] In preferred embodiments, the core module 2 may further comprise a particulate filter 42 provided to filter the liquid stream prior to input into the membrane contactor 8, to prevent damage to or fouling of the membrane element. The core module 2 may further comprise a pre-filter pressure sensor 44 and a post- filter pressure sensor 26 respectively upstream and downstream of the particulate filter 42. Each sensor 44, 26 is preferably connected to the controller, and a threshold maximum differential pressure sensed across the filter 42 may indicate a blockage in the filter, or that the filter needs to be replaced.

[0025] In preferred embodiments, the liquid feed pump 30 is a centrifugal, rotary lobe or double-screw positive displacement pump depending on the liquid being pumped, and the level of cleaning and sanitation required in the process. A liquid feed pump 30 may not be required in cases of degassing or low-dose C0₂ additions to wine, and where the gas management machine is not feeding a filling machine or a pressurised vessel. The gassing module 4 may further comprise a valve 56 for controlling flow into a centrifugal pump 30. Preferably, both valve 56 and pump 30 are controlled by the controller in response to sensed operational parameters. In order to maintain required levels of gas transfer to achieve repeatable results and/or to safeguard the system, the fluid input into the membrane contactor 8 may need to be shut off on occasion. The use of a centrifugal pump advantageously allows for the pump 30 to be dead-headed (ie operated with no flow through it) for a period of time without causing damage to the pump or other downstream components. For example, if excessively high pressure, low flow, high temperature, or combinations thereof, is detected in the liquid upstream of the membrane contactor 8 (potentially indicating a blockage in the fluid line or a fault in one of the components upstream of the membrane contactor 8), the valve 56 may be closed to suspend any liquid input into the pump 30 and hence suspend flow into the membrane contactor 8, to avoid damaging the membrane element. Once the fault has been resolved, the valve 56 may be reopened to refill the pump 30, and continue the gas transfer process. In other examples, the fluid input may need to be briefly interrupted in order to adjust one or more operating parameters, to obtain or maintain the required gas transfer into the liquid product.

[0026] In some embodiments, the gassing module 4 further comprises a variable frequency drive (not shown) for varying the speed or torque of the pump 30 according to command signals output by the controller. This allows the liquid input to be automatically and precisely controlled in response to the sensed operational parameters of the liquid and/or gas streams, to produce consistent levels of gas concentration in the liquid product even under rapidly varying input conditions. The ability to automatically control the pressure of the liquid stream may also help to safeguard the system. For example, the pressure of the liquid flow path in the membrane contactor 8 should consistently be higher than the pressure of the gas flow path, to protect the membrane element. The controller, via the variable speed drive, may be configured to precisely adjust the pressure output of the pump 30 in real time, in response to differential pressure measurements between the liquid and gas flow paths, to maintain the required pressure gradient.

[0027] In some embodiments, the gassing module 4 may comprise one or more sensors located downstream of the membrane contactor 8, connected to the controller and configured to sense operational parameters of the liquid product. The downstream liquid sensors may comprise a liquid outlet pressure sensor 54, a flow sensor (not shown), a gas flow control valve, a mass flow meter, and a gas sensor 60 configured to detect the concentration of a gas in the liquid, or combinations thereof. [0028] In the example shown in Figure 1 , the system 1 0 may be used for carbonating beverages. The level of carbonation required for a particular application may be achieved by varying one or more parameters such as liquid temperature, gas pressure and flow rate. For example, in contrast to the high carbonation of sodas, CO₂ may alternatively be added at a lower dose for use as a preservative during transport or to add a very slight spritz to a drink such as wine. Gas sensor 60 may be an in-line partial-pressure CO₂ sensor configured to measure CO₂ in the carbonated product in real time, to enable immediate automatic or manual adjustment of carbonation in situ. For example, this may be in response to uncontrolled system changes, eg changes in operating temperature as the room or apparatus heats up, or deliberate changes, eg if the user samples the product and desires more or less carbonation. CO₂ sensor 60 is preferably positioned as the most downstream equipment of the gassing module 4, resulting in a live and accurate measurement of the product as it leaves the system 10. Accordingly, the system 10 allows for precision dosing and quick response to changing system variables or different applications.

[0029] One advantage of the present gassing module is the wide range of operating temperatures. As discussed, prior art methods of forced carbonation require energy-intensive refrigeration of the liquid stream to maintain the low temperatures required for sufficient diffusion of gas into the liquid. In contrast, embodiments of the present system are configured to operate at temperatures up to about 25 °C, so that the entire gassing process may be performed at substantially ambient conditions.

[0030] In some embodiments, at least one operational parameter of the gas input into the membrane contactor 8 is also measured, eg via gas inlet pressure sensor 26 and/or gas inlet flow rate sensor 28, and provided as input to the controller. The gassing module 4 may further comprise a gas valve 58 controllable by the controller in response to the sensed operational parameter(s) of the liquid flow and/or gas flow. For example, input gas pressure may be regulated based on carbonation levels measured by the CO₂ sensor 60, by increasing the gas pressure and flow if more carbonation is required, and vice versa. [0031 ] Embodiments of the present invention provide a system for in-line degassing of liquids at substantially ambient temperature, thereby providing a safer and more energy-efficient method of degassing feed liquid compared to conventional heating methods.

[0032] Referring to the embodiment of Figure 2, the vacuum pump 38 of degassing module 6 is configured to evacuate the gas or gases transferred from the liquid into the gas flow path of the membrane contactor 8. Examples of suitable vacuum pumps include diaphragm pumps, rotary scroll pumps, liquid ring pumps, etc. Gas outlet pressure sensor 40 may monitor the pressure in the gas outlet line 36 to ensure that sufficient vacuum is being drawn for the particular application.

[0033] The degassing module 6 may further comprise a pre-membrane gas concentration sensor 46 and a post-membrane gas concentration sensor 48, connected in the liquid outlet line upstream and downstream of the contactor membrane 8 respectively. The controller may be configured to receive and compare data from the two sensors 46, 48, to quantify the change in the concentration of one or more gases in the liquid as a result of gas transfer within membrane contactor 8. This difference in gas concentration may define one of the operating parameters used to control the liquid feed pump 30, liquid valve 56, and/or gas valve 58.

[0034] In preferred embodiments, as shown in Figure 2, the pre-membrane gas sensor 46 and post-membrane gas sensor 48 are optical gas sensors configured to detect the concentration of oxygen (0₂) and/or C0₂ in the liquid. Optical sensors are advantageously highly accurate, do not require a separate or offline calibration mode, do not drift over time and are more sanitary than sensors which require probes containing electrolyte solutions. Accordingly, these sensors are particularly suited for degassing applications which are tightly regulated, eg in the healthcare and pharmaceutical industries.

[0035] The system 10 may additionally comprise a gas sweep 50 connected to the gas outlet port 16 of the membrane contactor 8, to enhance gas transfer from the liquid. Parameters of the gas sweep 50, eg flow rate or pressure, may be controlled by the controller in response to sensed operational parameters. For example, manual or automatic inlet pressure and vacuum pressure may be monitored and controlled. The removed gases (and the sweep gas, if provided) may be vented from the system.

[0036] In one example, system 10 is used to degas water for sterilisation of downstream equipment. In some cases, feed water may contain up to 20% NCG. Since 0₂ and C0₂ usually make up over 90% of the non-condensable gases present in process water, the requirements of EN 285 should be met if the degassing process can achieve about 95% removal of 0₂ and C0₂. Degassing control parameters such as input liquid flow rate, the vacuum drawn by vacuum pump 38 and sweep gas flow rate or pressure (if provided) may be controlled by the controller in response to the difference in 0 and C0₂ measurements obtained from the pre- membrane optical gas sensor 46 and the post-membrane optical gas sensor 48. The 0₂ and C0₂ sensors may not be included in some embodiments of the machines due to their expense. In some embodiments, the liquid may be recirculated one or more times through the process until the required NCG concentration of less than 3.5% is achieved. For example, the liquid may be output to a holding tank (not shown), and subsequently input back into the system for the recirculating step.

[0037] In another example, system 10 comprises both the gassing and degassing modules 4, 6, and operation of the system is switched between gassing and degassing modes by controlling operation of the vacuum pump 38. To operate in gassing mode, the vacuum pump 38 may be deactivated. Alternatively, the vacuum pump 38 may be activated (automatically or manually) only when the system is in standby (ie when there is no liquid flow, and gas transfer is not occurring in the membrane contactor 8), to remove gas condensate which tends to accumulate on the gas side of the membrane element during gassing. The vacuum pump 38 may be further configured to evacuate gas condensate from the membrane contactor 8 at the beginning and end of production. In the case of continuous runs where there is minimal stopping of the machine, a slow bleed of the gas through the outlet of the membrane contactor via a needle valve may create a means to expel any potential build-up of condensation. This feature may maximise the life of the membrane and increase carbonation efficiency, by restoring available surface area for gas transfer. To operate in degassing mode, the vacuum source 100 may be activated and the sweep or carrier gas (if provided) is drawn through the membrane contactor 8, as described above. Not every case requires the vacuum source 1 00 to be activated as often the pressure within the system is sufficient to evacuate gas and condensation from the line.

[0038] For example, in a brewery, the system 10 may firstly be operated in degassing mode to remove oxygen from brewing water. The system 1 may subsequently be used in gassing mode to carbonate the beverage, or in degassing mode prior to bottling, to reduce carbonation levels in an over-carbonated product (for example, due to fermentation).

[0039] In some embodiments, the controller is programmed with electronic pre- commissioning software, which tests and/or troubleshoots all of the sensors, components and alarms automatically. That is, the control unit tests the operation of each input and output component, and additionally pushes each component into its alarm-generating condition(s). This functionality saves time during installation and maintenance, and allows for remote diagnostics.

[0040] The invention will now be described in more detail, by way of illustration only, with respect to the following examples. The examples are intended to serve to illustrate this invention, and should not be construed as limiting the generality of the disclosure of the description throughout this specification.

Example 1 : Carbonating Kombucha

[0041 ] Kombucha was blended and fermented in batches of 1000L tanks. Hoses from the tanks were connected to the liquid inlet line 1 8 of the system 10 and high- pressure hoses connected liquid outlet line 20 to a filling/bottling machine. Kombucha was fed into liquid inlet line 18 and the centrifugal pump 30 pumped the liquid through the membrane contactor 8 and into the filler bowl (not shown). As the pump 30 pushed liquid through the machine, electromagnetic gas inlet valve 58 was opened to introduce C0₂ into the gas inlet port 14 of the membrane contactor 8. The gas outlet port 16 of the membrane contactor was closed so that all of the C0₂ diffused into the liquid. The gas flowing into the membrane was regulated by the controller to under approximately 4 bar and the gas flow rate was controlled via a manual needle valve.

[0042] In some trial runs, a controlled amount of C0₂ was allowed to vent from the gas outlet port 16 of the membrane contactor 8. The small amount of CO₂ acted as a sweep gas for removing dissolved 0₂ from the product, to produce a fresher and more shelf-stable product.

[0043] The following operational parameters determined the carbonation level that could be achieved in the liquid product: liquid temperature, liquid flow rate, gas pressure and gas flow rate. The process was run in manual mode, in which the operator determined the carbonation level required for each product and recorded the variables so they could be repeated with every batch. The operating temperature of the liquid is ideally 0 to 8°C for efficient transfer of C0₂, but the system 10 was able to operate up to about 30°C. This reduced the refrigeration requirement and allowed for contingency should a process failure occur (eg refrigeration system downtime).

[0044] The Kombucha bottling line did not have an inlet valve connecting to the liquid outlet port 1 2 of the system 10, so the system was operated in "Pressure" mode. The controller turned the system on and off as the pressure in the filler bowl of the bottling line increased and decreased. That is, a pressure sensor measured the pressure inside the filler bowl and matched it with the pump pressure to ensure that there was no excess C0₂ escaping from the beverage, which would cause foaming, CO2 losses and inconsistencies. Fluid input and gas transfer through the membrane element was continued until the pressure (originally set on the bottling machine) was achieved.

[0045] For Kombucha at 25°C, the minimum and maximum filler bowl pressures were set at 2.8 bar and 3 bar respectively. Once maximum pressure was reached, which typically took about 1 0-30 seconds, the system would go into "Standby" mode, in which the system was still running but the gas inlet valve 58 was closed and the pump 38 was paused. As the bottling line filled bottles from the filler bowl, the level and pressure in the filler bowl would decrease. Once the pressure dropped to the preset level of 2.8 bar, the system 1 0 resumed the carbonating process until the preset 3 bar maximum pressure in the filler bowl was achieved. This process continued until the operator stopped the machine. A carbonation level of between 3 to 5 g/L C0₂ in the Kombucha product was consistently achieved over multiple test runs. Preferred embodiments of the present system allow for carbonation levels between 0.5g/L to 14g/L.

[0046] In other embodiments, where the bottling line includes a valve connected to the liquid outlet line 20 of the system 10, the system may be operated in "Filler" mode, in which the liquid feed pump 30 is activated and gas inlet valve 58 is opened whenever the bottling line valve opens to feed more product into the filler bowl.

Example 2: Removing non-condensable gases from feed water for pharmaceutical applications

[0047] The system 10 may be retrofitted to existing plant equipment to remove NCG from feed water to the required level (eg in accordance with standard EN 285). The system may additionally or alternatively be used to remove volatile organic compounds (VOC) such as hydrogen sulphide from a liquid.

[0048] The membrane contactor 8 comprises one or more Liqui-Cel® hydrophobic membrane(s). Feed water is pumped into the liquid inlet line 18 of the membrane contactor 8 via an existing external pump and flows externally of the capillaries, from bottom to top of the membrane contactor 8 and into the existing steam generator or boiler, transferring gas from the water into the gas stream in the process. The transferred gas is evacuated by an oil-free pharmaceutical-grade vacuum pump 38, designed to operate continuously. The removed NCG is vented to atmosphere, or if required for Occupational Health and Safety reasons, may be exhausted externally.

[0049] Pre-membrane optical gas sensor 46 and post-membrane optical gas sensor 48 measure the concentration of dissolved O₂ and CO₂ in the liquid stream. The pre and post measurements of O₂ and CO₂ and the percentage removal efficiency are input to the controller and also displayed to the operator. Typically, at least 90% removal of 0₂ and C0₂ is required to guarantee that the EN285 requirement of 3.5% NCG is met. In automatic mode, the operator can input the minimum percentage removal efficiency for the process water and the controller will adjust operating parameters based on sensed parameters to achieve the required level of degasification. If the minimum degasification level specified by the operator cannot be achieved, the system will generate an alarm or notification.

[0050] Depending on the existing plant equipment, the system 1 0 can operate in duty/standby mode or in recirculation mode whereby the water is continuously degassed in recirculation until the downstream steam generator or boiler requires more water (eg via an inlet valve).

Example 3: Point-of-use benchtop medical degasser

[0051 ] The system 10 may be configured as a compact, benchtop degasser for medical or healthcare applications, in particular for feeding individual sterilisers in the central sterilisation department (CSD) of a hospital. The benchtop degasser may be installed or retrofit at the point of application (ie outputs to an existing steriliser which contains its own water boiler).

[0052] Water is input into liquid inlet line 18 from mains water, utilising mains water pressure. Particulate filter 42 is provided upstream of the membrane contactor 30 to protect the membrane element from particulate fouling, which reduces the gas removal efficiency. A pressure gauge is installed to measure the differential pressure across the filter. This pressure measurement is output to the operator to notify the operator if the filter is blocked or fouled and needs to be replaced. A liquid inlet needle valve is provided to regulate the maximum allowable flow rate through the system.

[0053] The membrane contactor 8 comprises one or more Liqui-Cel® hydrophobic membrane(s). Pre-membrane O₂ sensor 46 and post-membrane O₂ sensor 48 measure the 0₂ content of the feed water upstream of the membrane contactor and the degassed water downstream of the membrane contactor respectively. The gas removed from the water and transferred into the gas flow path in the membrane contactor 8 is evacuated by the vacuum pump 38. Gas outlet pressure sensor 44 monitors the evacuation pressure to ensure that an appropriate vacuum is being drawn for sufficient gas removal. The removed NCG is vented to atmosphere, or if required for Occupational Health and Safety reasons, may be exhausted externally. An electric solenoid valve is provided at the outlet of the system, to shut off output to the steriliser when the system 1 0 is not in operation.

[0054] The benchtop degasser may be provided to the hospital under a service contract, which covers installation and maintenance of the degasser for the contracted period. Installation involves calibrating the liquid flow rate with the input flow rate required by the existing steriliser. The mains water temperature is also tested, and if it is below a threshold temperature, the liquid flow rate into liquid inlet line 1 8 is reduced to compensate for the low temperature.

[0055] The ongoing servicing of the degasser may include removing the membrane element at regular intervals (eg, every 6 months) and replacing with a new or pretested and validated membrane, recalibrating or replacing the 0₂ sensors 46, 48 as necessary, testing and calibrating flow meters and replacing any other components of the benchtop degasser if required.

[0056] As the membrane elements can be very expensive and require regular servicing and cleaning to ensure effectiveness and longevity, the present method of providing the benchtop degasser under a maintenance contract provides a convenient service for hospitals, while ensuring proper maintenance of the degasser. The membrane elements removed for servicing are put through an intensive cleaning and testing protocol, which may include:

• recording on a database the serial number of each membrane element and linking the number to the associated machine in the field,

• 'wetting out' the membrane elements by removing the hydrophobicity with isopropyl alcohol to allow for a thorough chemical clean, eg with a proprietary potassium hydroxide solution,

• flushing with water and neutralising the caustic cleaning solution, • drying in a proprietary drying machine which uses clean warm air to dry the cleaned membranes and restore the original hydrophobicity,

• integrity testing, eg, a gas 'pressure hold' test to ensure that the membrane element and the housing are intact,

• testing the membrane element for NCG removal efficiency and adherence to EN 285 regulations by testing steam generated from the degassed water, and

• certifying that the membranes have been cleaned and tested to meet the NCG removal requirements of EN 285. This is conducted by measuring the most common NCG in water, 0₂ and C0₂ via optical dissolved measurement.

[0057] Conventionally, the CSD of a hospital would purchase standalone membrane elements and build custom rigs for retrofitting the membranes to existing sterilisation equipment. The present benchtop degasser advantageously provides the hospital or healthcare provider with an integrated testing and degassing unit that allows for inline measurement of NCG in the degassed water, and manual or automatic adjustment of operating parameters to match the required NCG removal. Further, the present method of providing and servicing the benchtop degasser advantageously allows the hospital or healthcare provider to outsource maintenance and certification of the degasser.

[0058] Embodiments of the present invention provide modular systems for in-line gassing and/or degassing of liquids that are both generally and specifically useful for real-time control of the multiple, interdependent variables affecting the gas transfer process.

[0059] Embodiments of the present invention additionally or alternatively provide modular systems for quickly and easily modifying the gas transfer process to produce a desired change in results, eg, real time adjustment of carbonation level, conversion between gassing and degassing modes, etc.

[0060] For the purpose of this specification, the word "comprising" means "including but not limited to," and the word "comprises" has a corresponding meaning. [0061 ] The above embodiments have been described by way of example only and modifications are possible within the scope of the claims that follow.

Claims

1 . A modular system for gassing and degassing liquids, comprising:

a controller;

wherein the gassing module comprises:

a gas inlet line connected to the gas inlet port of the membrane contactor;

a gas inlet pressure sensor and a gas inlet flow sensor connected in the gas inlet line, and connected to the controller;

wherein the degassing module comprises:

a gas outlet line connected to the gas outlet port of the membrane contactor;

2. The system of claim 1 , wherein the core module further comprises a particulate filter connected in the liquid inlet line between the liquid feed pump and the liquid inlet port of the membrane contactor.

3. The system of claim 1 or 2, wherein the core module further comprises a pre- filter pressure sensor connected in the liquid inlet line upstream of the particulate filter, and a post-filter pressure sensor connected in the liquid inlet line downstream of the particulate filter, wherein the pre-filter pressure sensor and the post-filter pressure sensor are each connected to the controller.

4. The system of any one of the preceding claims, wherein the degassing module further comprises a pre-membrane gas concentration sensor connected in the liquid inlet line upstream of the contactor membrane, and a post-membrane gas concentration sensor connected in the liquid outlet line downstream of the contactor membrane, wherein the pre-membrane gas concentration sensor and the post-membrane gas concentration sensor are each connected to the controller.

5. The system of any one of the preceding claims, where the gassing module and/or the degassing module further comprises a gas sweep connected to the gas outlet port of the membrane contactor.

6. The system of any one of the preceding claims, wherein the gassing module further comprises a liquid inlet temperature sensor connected in the liquid inlet line upstream of the contactor membrane, and a liquid outlet pressure sensor connected in the liquid outlet line downstream of the contactor membrane, wherein the liquid inlet temperature sensor and the liquid outlet pressure sensor are each connected to the controller.

7. The system of any one of the preceding claims, wherein the liquid feed pump of the gassing module comprises a centrifugal pump.

8. The system of claim 7, wherein the gassing module further comprises a valve upstream of the liquid feed pump, wherein upon detection of a threshold high pressure and/or threshold low flow and/or threshold high temperature in the liquid inlet line, the controller is configured to close the valve to suspend liquid input to the pump.

9. The system of any one of the preceding claims, comprising both the gassing module and the degassing module, wherein operation of the system is switched between gassing and degassing modes by controlling operation of the vacuum pump.

10. The system of claim 9 in gassing mode, wherein the vacuum pump is configured to evacuate gas condensate from the membrane contactor when the system is in standby.

1 1 . The system of any one of the preceding claims, wherein gassing may be performed at up to approximately 25 °C.

12. The system of claim 10 or 1 1 in degassing mode, wherein the vacuum pump is activated to evacuate gas transferred from the liquid to the gas within the membrane contactor.