A liquid product is dispensed via a membrane contactor. The contactor employs a plurality of gas-permeable hollow fibers. The contactor has a gas port communicating with the interior of the fibers and input and output ports for liquid communicating with space within the contactor surrounding the fib
A liquid product is dispensed via a membrane contactor. The contactor employs a plurality of gas-permeable hollow fibers. The contactor has a gas port communicating with the interior of the fibers and input and output ports for liquid communicating with space within the contactor surrounding the fibers. A gas comprising carbon dioxide or nitrous oxide is dissolved in the liquid in the contactor. The gas at a controlled pressure is supplied to the gas port. The liquid is supplied at a higher pressure than the gas to the input port for liquid from a supply of such liquid via a first valve having a first valve inlet port communicating with the supply of liquid and a first valve outlet port communicating with the inlet port for liquid. Liquid with the gas dissolved therein is dispensed from the outlet port for liquid via a dispense tap to ambient. The dispensing liquid step includes a start dispense step in which dispensing commences and a stop dispense step in which dispensing is stopped. The first valve is opened with the dispensing tap in the start dispense step, and is closed in the stop dispense step. Pressure build-up is relieved in liquid in communication with the space within the contactor surrounding the fibers after closure of the first valve and while maintaining the first valve closed. The balance between gas pressure and liquid pressure during the systems' standby periods protects the membranes from flooding.
대표청구항▼
1. Apparatus for adding a gas comprising carbon dioxide or nitrous oxide to a liquid during dispense thereof from a supply of said liquid; the apparatus comprising: a membrane contactor having a contactor housing with a plurality of gas-permeable hollow fibres mounted therein, the contactor housing
1. Apparatus for adding a gas comprising carbon dioxide or nitrous oxide to a liquid during dispense thereof from a supply of said liquid; the apparatus comprising: a membrane contactor having a contactor housing with a plurality of gas-permeable hollow fibres mounted therein, the contactor housing having a gas port communicating with the interior of the fibres and adapted to receive said gas at a controlled pressure thereat, and input and output ports for liquid communicating with space within the contactor housing surrounding the fibres;a first valve having a first valve inlet port arranged for communication with the supply of liquid and a first valve outlet port communicating with the inlet port for liquid and arranged for supply of said liquid to the inlet port for liquid at a higher pressure than said controlled gas pressure;a dispense tap coupled to the output port for liquid and adapted to dispense liquid to ambient:and a control system coupled to monitor opening and closing of the first valve and the dispense tap, whereby to the control a start dispense step in which dispensing commences and a stop dispense step in which dispensing is stopped, the control system being arranged to open the first valve with said dispensing tap in said start dispense step, and being arranged to close said first valve in said stop dispense step, and to relieve pressure build-up in liquid in communication with the said space after closure of the first valve and while maintaining the first valve closed. 2. Apparatus according to claim 1, wherein the control system is arranged to relieve pressure build-up in liquid in communication with the said space by causing at least a predetermined volume of liquid to be withdrawn from an otherwise closed volume of liquid in communication with the said space. 3. Apparatus according to claim 2, wherein said predetermined volume comprises a characteristic volume corresponding to the expansion of liquid that would otherwise occur in said space absent said withdrawal of said predetermined volume due to continuing dissolving of the gas in liquid in said space after stopping dispense. 4. Apparatus according to claim 3, wherein the characteristic volume is determined by the formula (1) below: Δv=K·Vc·C·(1−0.5η) (1) where K=a constant specific to the particular gas, 7.2×10−4 when the gas is carbon dioxideΔv=characteristic volume, in millilitersVc=liquid volume of contactor, in millilitersC=saturation level of the gas in the liquid, in grams per literη=efficiency of contactor at continuous flow condition. 5. Apparatus according to claim 1, wherein the control system is arranged to relieve pressure build-up in liquid in communication with the said space by allowing a closed volume of liquid in communication with the said space to expand by at least a characteristic volume. 6. Apparatus according to claim 5, wherein the characteristic volume is determined by the formula (1) below: Δv=K·Vc·C·(1−0.5η) (1) where K=a constant specific to the particular gas, 7.2×10−4 when the gas is carbon dioxideΔv=characteristic volume, in millilitersVc=liquid volume of contactor, in millilitersC=saturation level of the gas in the liquid, in grams per literη=efficiency of contactor at continuous flow condition. 7. Apparatus according to claim 1, wherein the control system is adapted to close the dispense tap at least a pre-determined interval corresponding to said predetermined volume after closure of the first valve. 8. Apparatus according to claim 1, wherein the control system includes a second valve having a second valve input port and a second valve output port, and coupled to receive liquid from said space at said second valve input port, the second valve being controlled to open in the interval from and including one of opening of the first valve and closure of the first valve and being controlled to close a pre-determined interval corresponding to said predetermined volume after closure of the first valve, the second valve output port being coupled to a position arranged in use to be permanently at a pressure below that of said space. 9. Apparatus according to claim 8, wherein the control system is adapted to open the first and second valves and the dispense tap at the same time. 10. Apparatus according to claim 8, wherein the control system is adapted to open the second valve when the first valve closes. 11. Apparatus according to claim 8, wherein the second valve outlet port communicates with the outlet of the dispense tap. 12. Apparatus according to claim 8, further comprising a pump having a suction side and a delivery side, the delivery side being coupled to the first valve inlet port for delivering liquid at said higher pressure, and the suction side being arranged for communication with a supply of the liquid at a pressure lower than said higher pressure; and wherein the second valve outlet port communicates with one of said suction side and said supply. 13. Apparatus according to claim 1, wherein the liquid comprises a beverage supplied substantially at ambient pressure in a bag-in-box container, and wherein a pump having a suction side and a delivery side is coupled between the container and the first valve, the delivery side being coupled to the first valve inlet port for delivering liquid at said higher pressure, and the suction side being coupled to said container. 14. Apparatus according to claim 4, further comprising a diaphragm chamber having respective compartments on either side of a flexible diaphragm, one said compartment being permanently in communication with liquid in the said space, and the other said compartment being arranged to communicate with gas at the gas port to allow said closed volume of liquid to expand. 15. Apparatus according to claim 14, wherein the other said compartment is coupled to the common port of a three port valve; said three port valve having two further ports, one coupled to receive said gas from a source thereof, and the other coupled to said gas port, and having a first state in which said common port communicates only with said one port, and a second state in which said common port communicates only with said other port.
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이 특허에 인용된 특허 (5)
Page,John K. R.; Page,Mark George, Apparatus for the preparation of liquids for the dispense of beverages.
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