CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to co-pending U.S. Provisional Patent Application No. 62/457,460, filed on February 10, 2017, the entire content of which is incorporated herein by reference.

BACKGROUND

[0002] The present disclosure relates to capturing, purifying, and storing carbon dioxide, and more particularly to capturing, purifying, and storing carbon dioxide obtained as a byproduct of a fermentation process.

[0003] Fermentation produces as a byproduct carbon dioxide gas. As an example, breweries produce large amounts of carbon dioxide during the fermentation stage of producing beer. These same breweries also use large amounts of beverage-grade carbon dioxide for carbonating beer, packaging, and as a push gas, among other things. A brewery typically releases the carbon dioxide produced during fermentation and must separately purchase carbon dioxide for the latter processes, since the raw carbon dioxide byproduct from fermentation is not of beverage-grade quality.

SUMMARY

[0004] The disclosure provides, in one aspect, a system for capturing and purifying carbon dioxide obtained from a fermentation vessel as a byproduct of a fermentation process. The system includes a gas purification assembly configured to receive carbon dioxide gas from the fermentation vessel and to output a purified carbon dioxide gas, a compressor configured to compress the purified carbon dioxide gas to a pressure of at least 500 psi, and a condenser including a cooling medium having an average temperature not less than 0 degrees Fahrenheit, the condenser configured to receive the purified carbon dioxide gas from the compressor and to cool the purified carbon dioxide gas such that at least a portion of the purified carbon dioxide gas liquefies.

[0005] The disclosure provides, in another aspect, a method of capturing and purifying carbon dioxide obtained from a fermentation vessel as a byproduct of a fermentation process. The method includes recovering carbon dioxide from the fermentation vessel, after recovering, purifying the carbon dioxide, after purifying, compressing the carbon dioxide to a pressure of at least 500 pounds per square inch, and after compressing, cooling the carbon dioxide to liquefy at least a portion of the carbon dioxide.

[0006] The disclosure provides, in another aspect, a method of capturing carbon dioxide from a fermentation source and producing beverage-grade carbon dioxide. The method includes recovering carbon dioxide from the fermentation source purifying the carbon dioxide to at least a 99.9% purity level by volume, pressurizing the carbon dioxide to a pressure of at least 500 pounds per square inch, and liquefying at least a portion of the carbon dioxide by cooling the carbon dioxide to a temperature less than 87.98 degrees Fahrenheit using a cooling medium having an average temperature not less than 0 degrees Fahrenheit.

[0007] The disclosure provides, in another aspect, a system for capturing and purifying carbon dioxide obtained from a fermentation vessel as a byproduct of a fermentation process. The system includes a connection assembly coupled to the fermentation vessel to receive carbon dioxide gas from the fermentation vessel, a first storage volume located downstream of the connection assembly, the first storage volume configured to store the carbon dioxide gas, and a blower configured to transfer the carbon dioxide gas from the first storage volume. The system also includes a gas purification assembly configured to receive the carbon dioxide gas from the blower and to output a purified carbon dioxide gas. The gas purification assembly includes a water stripper assembly with an inlet, an outlet, and a water column disposed between the inlet and the outlet such that carbon dioxide gas that enters the inlet flows through the water column before reaching the outlet. The gas purification assembly also includes a gas dryer assembly with a desiccant material, and a gas polisher assembly including at least one filter configured to remove impurities from carbon dioxide gas by absorption, adsorption, oxidation or dissolution. The system also includes a second storage volume located downstream of the gas purification assembly and configured to store the purified carbon dioxide gas. The system also includes a compressor configured to compress the purified carbon dioxide gas to a pressure of at least 500 pounds per square inch, and a cooling assembly including a cooling medium having an average temperature not less than 0 degrees Fahrenheit. The cooling assembly is configured to cool the purified carbon dioxide gas such that at least a portion of the purified carbon dioxide gas liquefies.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a schematic of a system for capturing carbon dioxide according to an embodiment of the disclosure.

[0009] FIG. 2 is a schematic of a fermentation tank connection assembly of the system of

FIG. 1.

[0010] FIG. 3 is a schematic of a manifold assembly of the system of FIG. 1.

[0011] FIG. 4 is a schematic of a first intermediate storage assembly of the system of FIG. 1.

[0012] FIG. 5 is a schematic of a gas booster assembly of the system of FIG. 1.

[0013] FIG. 6 is a schematic of a water stripper assembly of the system of FIG. 1.

[0014] FIG. 7 is a side view of the water stripper assembly of FIG. 6.

[0015] FIG. 8 is a schematic of a gas dryer assembly of the system of FIG. 1.

[0016] FIG. 9 is a schematic of a gas polisher assembly of the system of FIG. 1.

[0017] FIG. 10 is a side view of the gas polisher assembly of FIG. 9.

[0018] FIG. 11 is a schematic of a second intermediate storage assembly of the system of

FIG. 1.

[0019] FIG. 12 is a schematic of a compressor assembly of the system of FIG. 1.

[0020] FIG. 13 is a side view of a condenser assembly of the system of FIG. 1. [0021] FIG. 14 is a schematic of a storage assembly of the system of FIG. 1.

[0022] FIG. 15 is a schematic of the components of the system of FIG. 1 arranged on a skid.

[0023] FIG. 16 is a schematic of a controller of the system of FIG. 1.

[0024] FIG. 17 is a control diagram illustrating control of the fermentation tank connection assembly of FIG. 2.

[0025] FIG. 18 is a control diagram illustrating control of the manifold assembly of FIG. 3.

[0026] FIG. 19 is a control diagram illustrating control of the gas booster assembly of FIG. 5.

[0027] FIG. 20 is a control diagram illustrating control of the compressor assembly of FIG. 12.

[0028] FIG. 21 is a control diagram illustrating control of the condenser assembly of FIG. 13.

[0029] FIG. 22 is a phase diagram illustrating an exemplary carbon dioxide liquefaction process carried out by the system of FIG. 1.

[0030] Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The disclosure is capable of supporting other embodiments and of being practiced or of being carried out in various ways.

DETAILED DESCRIPTION

[0031] FIG. 1 illustrates a system 10 for capturing and purifying carbon dioxide obtained as a byproduct of a fermentation process. The illustrated system 10 includes a fermentation tank connection assembly 100 coupled to a fermentation vessel 15, a manifold assembly 200, a first intermediate storage assembly 300, a gas booster assembly 400, and a gas purification assembly 500. The gas purification assembly 500 includes a water stripper assembly 510, a gas dryer assembly 540, and a gas polisher assembly 570. The system 10 further includes a second intermediate storage assembly 600, a compressor assembly 700, a condenser assembly 800, and a storage assembly 900. These assemblies are interconnected by fluid transfer components, such as piping, valving, and metering devices, which need not be specifically described. In the illustrated embodiment, the system 10 further includes a controller 1000 in communication with the electrical and electronic components of the system 10. It should be understood that the assemblies and components of the system 10 can be connected in a variety of different ways. In addition, one or more of the assemblies may be omitted, and other or additional assemblies may be incorporated into the system 10.

[0032] With reference to FIG. 2, the fermentation tank connection assembly 100 includes a gas line 105 coupled to the fermentation tank 15 (FIG. 1) and terminating at an airlock 110. The illustrated airlock 110 has a volume of about five gallons, but may be larger or smaller depending on the capacity of the system 10 for a given application. A foam detection line 115 and a system input line 120 are coupled to the gas line 105 between the fermentation tank 15 and the airlock 110. A sensor 125 is provided in the foam detection line 115 and communicates with the controller 1000. The sensor 125 may be an optical sensor, a conductivity sensor, or any other sensor able to detect the presence of foam (a "foam sensor") in the foam detection line 115. In other embodiments, the foam detection line 115 may be omitted, and the sensor 125 may be provided in the gas line 105 or the system input line 120. The connection assembly 100 further includes first and second solenoid valves 130, 135 situated in the system input line 120 and in communication with the controller 1000, and a sample line 140 that branches from the system input line 120 from between the solenoid valves 130, 135.

[0033] The system 10 may be used to capture carbon dioxide from a single fermentation tank 15 or from multiple fermentation tanks 15. In the latter case, the system 10 includes a plurality of fermentation tank connection assemblies 100, each connecting to a corresponding one of the fermentation tanks 15. Alternatively, a single connection assembly 100 may include multiple gas lines 105 to consolidate carbon dioxide gas from a plurality of fermentation tanks 15.

[0034] Now referring to FIG. 3, the manifold assembly 200 includes a primary manifold 205 and a sample manifold 210. The primary manifold 205 is coupled to the system input line 120 of each fermentation tank connection assembly 100 at a point downstream of the associated second solenoid valve 135. An outlet 215 of the primary manifold 205 is coupled to the first intermediate storage assembly 300 (see FIG. 4). The sample manifold 210 is coupled to the sample line 140 of each fermentation tank connection assembly 100. A third solenoid valve 220 is disposed in each sample line 140 upstream of the sample manifold 210 for controlling the flow of gas into the sample manifold 210. An oxygen meter 225, which communicates with the controller 1000, is provided in the sample manifold 210. The oxygen meter 225 measures the oxygen concentration of a gas within the sample manifold 210. In some embodiments, the oxygen meter 225 may include both a concentration percentage meter (a first meter) that measures the oxygen concentration as a percentage and an oxygen content meter (a second meter) that measures oxygen content in parts per million. The second meter may be more sensitive than the first meter and is preferably located downstream of the first meter. An additional valve (not shown) may be provided between the first meter and the second meter to prevent the second meter from being exposed to oxygen concentrations outside of its operating range. In some embodiments, the sample manifold 210 may include a vacuum pump (not shown) to draw sample gas into the sample manifold 210 and/or purge sample gas from the sample manifold 210. Alternatively, a positive pressure pump or compressor may be used to send gas into the sample manifold 210 and/or purge sample gas from the sample manifold 210.

[0035] With reference to FIG. 4, the first intermediate storage assembly 300 includes an input line 305 coupled to the outlet 215 of the primary manifold 205, an input valve 310, an output line 315 coupled to the gas booster assembly 400 (see FIG. 5), an output valve 320, and a first storage vessel or volume 325 located between the input line 305 and the output line 315. A first pressure sensor 330, which communicates with the controller 1000, is coupled to the first storage vessel 325 for monitoring its internal pressure. In the illustrated embodiment, the first pressure sensor 330 is a magnetic float sensor, but other types of pressure sensors (including analog or digital pressure sensors or switches) may be used. In some embodiments, the pressure sensor 330 may be a pressure switch in direct communication with the output valve 330 and/or the gas booster assembly 400. The illustrated first intermediate storage assembly 300 also includes a pressure regulating valve or device 335, such as a burst disk. In other embodiments, other pressure regulating devices, including manual, automatic, spring-operated, or computer- operated pressure regulating devices may be used. [0036] Referring to FIG. 5, the gas booster assembly 400 includes a blower 405, which alternatively may be a compressor or pump, in communication with the controller 1000. The output line 315 of the first intermediate storage assembly 300 is coupled to an inlet 410 of the blower 405, and an outlet 415 of the blower 405 is coupled to the water stripper assembly 510 of the gas purification assembly 500 (see FIGS. 6-7). In other embodiments, the gas booster assembly 400 may be positioned between the gas purification assembly 500 and the second intermediate storage assembly 600.

[0037] With reference to FIGS. 6 and 7, the water stripper assembly 510 includes a water vessel 512 having an upper end 514, a lower end 516, and inlet and outlet ports 518, 520 located at the upper end 514. In other embodiments, the inlet and outlet ports 518, 520 may be positioned in other locations, such as on a side of the vessel 512. Additional valves, ports, and the like may also be provided to facilitate servicing the water stripper assembly 510. In the illustrated embodiment, the inlet port 518 is coupled to the outlet 415 of the blower 405. The outlet port 520 is coupled to the gas dryer assembly 540 (see FIG. 8). The water vessel 512 is at least partially filled with water so as to form a water column 522. A tube 524 extends from the inlet port 518 into the water column 522 and terminates proximate the lower end 516.

Accordingly, carbon dioxide gas that enters the water vessel 512 through the inlet 518 flows or bubbles up through the water column 522 before reaching the outlet 520. In the illustrated embodiment, the water vessel 512 also includes an access port 526 to facilitate draining and/or filling the water vessel 512.

[0038] Referring to FIG. 8, the illustrated gas dryer assembly 540 includes a desiccant cartridge 542 having an inlet 544 coupled to the outlet port 520 of the water stripper assembly 510 and an outlet 546 coupled to the gas polisher assembly 570 (see FIG. 9). The desiccant cartridge 542 includes desiccant material, which, in the illustrated embodiment, includes about 1.5 pounds of blue silica beads. In other embodiments, other desiccant materials or amounts of desiccant may be used. In some embodiments, the desiccant material may change color when saturated to indicate when a replacement cartridge is needed. Alternatively, in other

embodiments the gas dryer assembly 540 may include other drying components, such as a refrigeration unit, one or more membranes, and the like. [0039] With reference to FIGS. 9 and 10, the gas polisher assembly 570 includes an inlet 572 coupled to the outlet 546 of the gas dryer assembly 540, an outlet 574 coupled to the second intermediate storage assembly 600 (see FIG. 11), and first and second filter stages 576, 578 disposed between the inlet 572 and the outlet 574. In some embodiments, the first and second filter stages 576, 578 are housed within separately removable cartridges, and in other

embodiments, the first and second filter stages 576, 578 may be housed within a single removable cartridge. In the illustrated embodiment, the first filter stage 576 includes activated carbon and/or other media suitable for removing sulfurous compounds. The second filter stage includes potassium permanganate, activated carbon, and/or other media suitable for removing other unwanted contaminants, such as hydrocarbons, volatile organic compounds, aldehyde, oxygenates, and aromatics. In some embodiments, the positions of the first and second filter stages 576, 578 may be reversed. In other embodiments, the gas polisher assembly 570 may include any number, type, and arrangement of filtering devices configured to remove

contaminants from the carbon dioxide gas.

[0040] Referring to FIG. 11, the second intermediate storage assembly 600 includes an input line 605, an input valve 610, an output line 615, an output valve 620, and a second storage vessel or volume 625 between the input line 605 and the output line 615. The input line 605 is coupled to the outlet 574 of the gas polisher assembly 570, and the output line 615 is coupled to the compressor assembly 700 (see FIG. 12). A second pressure sensor 630, which communicates with the controller 1000, is coupled to the second storage vessel 625 for monitoring its internal pressure. In the illustrated embodiment, the second pressure sensor 630 is a magnetic float sensor, but other types of pressure sensors may be used. Alternatively, the second pressure sensor 630 may be a pressure switch in direct communication with the output valve 630 and/or the compressor assembly 600. The illustrated second intermediate storage assembly 600 also includes a pressure regulating valve or device 635, such as a burst disk. In other embodiments, other pressure regulating devices, including manual, automatic, spring-operated, or computer- operated pressure regulating devices may be used.

[0041] Now referring to FIG. 12, the compressor assembly 700 includes a compressor 705 in communication with the controller 1000. The output line 615 of the second intermediate storage assembly 600 is coupled to an inlet 710 of the compressor 705, and an outlet 715 of the compressor 705 is coupled to the condenser assembly 800 (see FIG. 13). In the illustrated embodiment, the compressor 805 has a power of about 0.7 horsepower, a maximum flow rate of about 0.2 cubic feet per minute, and a maximum discharge pressure of about 2,000 psi. In other embodiments, however, the compressor's power, flow rate, and/or discharge pressure may vary. In some embodiments, the compressor assembly 700 may include an integrated aftercooler to cool the carbon dioxide exiting the compressor 705. In such embodiments, the condenser assembly 800 may be omitted.

[0042] With reference to FIG. 13, the condenser assembly 800 includes a condenser 805 having an inlet 810 coupled to the outlet 715 of the compressor 705 and an outlet 815 coupled to the storage assembly 900 (see FIG. 14). A heat transfer coil 820 extends between the inlet 810 and the outlet 815. In the illustrated embodiment, the coil 820 is made of stainless steel tubing having a pressure rating greater than the maximum discharge pressure of the compressor 705. For example, the coil 820 may have a pressure rating of about 4,000 psi. The coil 820 is encased in a chamber 825 having a cooling medium inlet 830 and a cooling medium outlet 835. In the illustrated embodiment, the cooling medium inlet 830 and outlet 835 are positioned in a counter- flow configuration such that cooling medium may flow opposite the direction carbon dioxide flows through the coil 820. In other embodiments, the cooling medium inlet 830 and outlet 835 may be positioned in a parallel flow configuration such that cooling medium may flow parallel with the direction carbon dioxide flows through the coil 820. A temperature sensor 840 is provided proximate the cooling medium outlet 835 for measuring the temperature of cooling medium leaving the chamber 825. In the illustrated embodiment, the cooling medium is water, and the cooling medium inlet 830 may be connected to a municipal water supply, for example. In some embodiments, other cooling mediums such as air or glycol may be used. A cooling valve (not shown) in communication with the controller 1000 is provided to control the flow of cooling medium through the cooling medium inlet 830.

[0043] With reference to FIG. 14, the storage assembly 900 includes one or more storage cylinders 905, such as standard 135 pound carbon dioxide cylinders. The storage assembly 900 further includes a regulator 910 and a storage input valve 915 that is in communication with the controller 1000. In some embodiments, the storage assembly 900 may further include one or more additional filters 912 (e.g., a gas filter for impurity removal, a coalescing filter, and the like) positioned proximate the regulator 910. The storage input valve 915 is coupled to the outlet 815 of the condenser assembly 800. In some embodiments, a vaporizer 917 may be provided at an outlet of the storage assembly 900 to facilitate gas flow out of the storage cylinders 905 by inhibiting line freezing and the formation of frost. A vapor heater 919 may also or alternatively be provided at the outlet of the storage assembly 900.

[0044] In the illustrated embodiment, the storage assembly 900 also includes a cylinder cooler 920 associated with each of the storage cylinders 905. In some embodiments, each cylinder cooler 920 includes a cooling coil (not shown) at least partially surrounding the storage cylinder 905 and having an inlet at a bottom end of the coil and an outlet at a top end of the coil. Alternatively, the positions of the inlet and outlet may be reversed. The cooling coil may be made of copper tubing or any other thermally-conductive material and may have a diameter of about 3/8 of an inch, for example. The cooling coil may include a plurality of helical loops, with adjacent loops spaced apart at a distance between about zero inches and about twelve inches. In some embodiments, adjacent loops may be spaced apart at a distance of about one half of an inch.

[0045] A pump (not shown) may be provided to circulate cooling fluid, such as water, glycol, or any other suitable cooling fluid, through the coil of each cylinder cooler 920. The cooling fluid may be pressurized or may be at atmospheric pressure. The pump may form a closed loop with the cooling coils, or the pump may draw cooling fluid from a reservoir that receives a discharge flow of cooling fluid from the outlet of each cooling coil. The cylinder coolers 920 may be connected to the pump in parallel or in series.

[0046] In some embodiments, a heat exchanger may be provided between the pump and the cylinder coolers 920 to lower the temperature of the cooling fluid entering the cylinder coolers 920. In other embodiments, the heat exchanger may be configured to cool the reservoir. In some alternative embodiments, the cylinder coolers 920 may be connected to a municipal water supply. In other embodiments, the cooling coils may be omitted such that each cylinder cooler 920 is configured as a bath in which at least a portion of the storage cylinder 905 is submerged. In yet other embodiments, the cylinder coolers 920 may be omitted. For example, in some embodiments, the cylinders 905 may be air cooled. The cylinders 905 may be actively air- cooled, such as by a fan (not shown) that circulates air over the cylinders 905. Alternatively, the cylinders 905 may be passively air-cooled, i.e., with no forced air circulation.

[0047] FIG. 15 illustrates the system 10 arranged on a platform or skid 50. The skid 50 may include a base and a variety of frames and mounting points for mounting the components of the system 10. In the illustrated embodiment, the manifold assembly 200, first intermediate storage assembly 300, gas booster assembly 400, gas purification assembly 500, second intermediate storage assembly 600, compressor assembly 700, condenser assembly 800, and storage assembly 900 are fixed to a square skid 50 having a length of about three feet and a width of about three feet. As such, the system 10 fits within a compact footprint of about nine square feet. In other embodiments, the skid 50 may have other dimensions, and the system 10 may be arranged in other ways or split across multiple skids.

[0048] Now referring to FIG. 16, the controller 1000 includes a plurality of electrical and electronic components that provide power, operational control, and protection to the components and modules within the controller 1000. For example, the controller may include an electronic processor or central processing unit 1005 (e.g., a programmable microprocessor, microcontroller, or similar device), non-transitory, machine-readable memory 1010, and an input/output interface 1015. Software included in the implementation of the controller 1000 can be stored in the memory 1010. The software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The controller 1000 is configured to retrieve from memory 1010 and execute, among other things, instructions related to the control processes and methods described herein. In other

embodiments, the controller 1000 may include additional, fewer, or different components.

[0049] The controller 1000 is communicatively coupled to the various valves 130, 135, 220, 310, 320, 610, 620, 915, the blower 405, and the compressor 705 (e.g., via the input/output interface 1015) to control their operation. The controller 1000 is also communicatively coupled to the sensor 125, the oxygen meter (or meters) 225, the pressure sensors 330, 630, and the temperature sensor 840 (e.g., via the input/output interface 1015) to receive feedback from the sensors. The controller 1000 may operate the system 10 automatically, with no or minimal operator input. The controller 1000 may communicate with any of the connected electric or electronic components of the system 10 via wired connection, wireless connection, or a combination of wired and wireless connections. In some embodiments, the controller 1000 may communicate with any of the connected electric or electronic components of the system 10 via the internet, and the controller 1000 may receive commands and transmit operating information over the internet, allowing the system 10 to be controlled and/or monitored remotely.

[0050] In operation, each fermentation tank connection assembly 100 receives raw carbon dioxide gas produced from a fermentation process occurring within the fermentation vessel(s) 15 (FIG. 1). During ordinary operation, the gas passes through the gas line 105 to the system input line 120 (FIG. 2). The gas then passes through the solenoid valves 130, 135 in the system input line 120 before entering the manifold assembly 200. A portion of the gas is routed into the foam detection line 115.

[0051] Referring to FIG. 17, the controller 1000 continuously or incrementally monitors the sensor 125 in the foam detection line 120 (or alternatively, in the gas line 105 or the system input line 120) at step S10. Based on feedback from the sensor 125, the controller 1000 determines whether there is foam present at step S15 (e.g., by comparing a value measured by the sensor 125 with a predetermined value). For example, in embodiments in which the sensor 125 is a conductivity sensor, the controller 1000 determines that no foam is present if the measured resistance is greater than a predetermined value (e.g., twenty micro-ohms). If the measured resistance is less than the predetermined value, the controller 1000 determines that foam is present. If no foam is present in the gas, the controller 1000 sends a signal to open the first solenoid valve 130 at step S20. If foam is present in the gas, the controller 1000 sends a signal to close the first solenoid valve 130 at step S25. This prevents gas and foam from advancing through the system input line 120 and diverts the flow of the foam-laden gas into the airlock 110. In the illustrated embodiment, gas that flows into the airlock 110 is slowly discharged into the atmosphere.

[0052] When the solenoid valves 130, 135 are open, the carbon dioxide gas travels through the system input line 120 to the manifold assembly 200, and a portion of the gas enters the sample line 140 for oxygen content testing (FIGS. 2 and 3). In the illustrated embodiment, the controller 1000 sequentially opens and closes the third solenoid valves 220 to obtain a sample of gas from each connected sample line 140 individually. Referring to FIG. 18, the controller 1000 opens one valve 220 at step SI 00, then activates the vacuum pump for a predetermined time period (e.g., thirty seconds) at step SI 05. After the time period elapses, the controller 1000 closes the valve 220 at step SI 10 and deactivates the vacuum pump at step SI 15. The controller 1000 then monitors the oxygen meter 225. The controller 1000 compares the measured oxygen concentration from the oxygen meter 225 with a predetermined oxygen concentration value at step S120. In some embodiments, the predetermined oxygen concentration value is thirty parts per million. In other embodiments, the predetermined oxygen concentration value is twenty- seven parts per million or less. Alternatively, the predetermined oxygen concentration value may be a concentration percentage, or any other value representative of a maximum permissible oxygen content.

[0053] If the measured oxygen concentration is less than the predetermined oxygen concentration value, indicating an acceptably low oxygen concentration, then the controller 1000 sends a signal to open the second solenoid valve 135 at step S125. This allows carbon dioxide to flow into the primary manifold 205, which leads to the first intermediate storage assembly 300. If the measured oxygen concentration is greater than the predetermined oxygen concentration value, the controller 1000 sends a signal to close the second solenoid valve 135 at step SI 30, which prevents gas from flowing into the first intermediate storage assembly 300. Accordingly, the controller 1000 can regulate the oxygen content of gas flowing into the first intermediate storage assembly 300. The controller 1000 returns to step S100 to open the next valve 220 in sequence and repeats the process.

[0054] In the illustrated embodiment, the first intermediate storage assembly 300

accumulates and temporarily stores the carbon dioxide gas exiting the primary manifold 205 (FIG. 4). Thus, the first intermediate storage assembly 300 acts as a flow rate buffer and may also inhibit the formation of negative pressure in the fermentation tanks 15 (FIG. 1) and any other upstream components. The controller 1000 continuously or incrementally monitors the first pressure sensor 330 to determine when the first storage vessel 325 reaches capacity at step S200. When the first pressure sensor 330 indicates that the vessel 325 is full (or reaches a desired fullness), the controller 1000 sends a signal to open the output valve 320 at step S205. The controller 1000 then activates the blower 405 at step S210. The blower 405 draws carbon dioxide out of the first storage vessel 325. After a predetermined time period or in response to feedback from the pressure sensor 330, the controller 1000 deactivates the blower 405 at step S220, and then closes the output valve 320 at step S215. Alternatively, if the first pressure sensor 330 includes a switch directly connected to the output valve 320 and the blower 405, actuation of the switch may actuate the output valve 320 and activate or deactivate the blower 405 without requiring communication with the controller 1000.

[0055] Alternatively, the first intermediate storage assembly 300 may be omitted. In such embodiments, the blower 405 may draw the carbon dioxide directly from the fermentation tanks 15. In such embodiments, the blower 405 is preferably a self-balancing compressor that adjusts its speed based on gas flow. The controller 1000 may adjust the operating speed of the blower 405 based on a detected pressure in the fermentation tank(s) 15, for example, which is indicative of the amount of carbon dioxide gas available to be drawn out of the fermentation tank(s) 15.

[0056] Referring to FIGS. 6-10, the blower 405 forces carbon dioxide gas through the purification assembly 500. In some embodiments, the blower 405 discharges gas at a pressure of about 15 psi. In some embodiments, the blower 405 discharges gas at a pressure between about 15 psi and about 150 psi. In some embodiments, the blower 405 discharges gas at a pressure between about 15 psi and about 50 psi. In some embodiments, the blower 405 discharges gas at a pressure between about 0 psi and about 150 psi. The purification assembly 500 then removes impurities and moisture from incoming carbon dioxide gas using the filtration principles of dissolution, adsorption, and absorption.

[0057] First, the gas enters the water stripper assembly 510 through the inlet port 518 (FIG. 6). The gas travels through the tube 524 to the bottom of the water column 522, and then bubbles up through the water column 522 before exiting through the outlet port 520. This removes impurities from the carbon dioxide gas by allowing dissolution of any water-soluble contaminants. The water stripper assembly 510 may also remove organic and inorganic particulate from the carbon dioxide gas as it flows through the water column 522.

[0058] After leaving the water stripper assembly 510, the partially-purified carbon dioxide gas enters the gas dryer assembly 540. The gas flows through the desiccant cartridge 542, which removes moisture from the gas. In the illustrated embodiment, carbon dioxide gas that exits the gas dryer assembly 540 has a dew point equivalent less than or equal to minus thirty degrees Fahrenheit, and/or a moisture content no greater than twenty parts per million.

[0059] The dried and partially-purified carbon dioxide gas next enters the gas polisher assembly 570. The gas flows through the filter stages 576, 578, which remove a variety of contaminants. In the illustrated embodiment, the first filter stage 576 removes sulfurous compounds (e.g., hydrogen sulfide) from gas passing through the polisher assembly 570. The second filter stage 578 removes a broad spectrum of compounds, including but not limited to hydrocarbons, volatile organic compounds, aldehyde, oxygenates, and aromatics. Purified carbon dioxide gas exits the gas polisher assembly 570 at least 99.9% pure by volume, in some embodiments.

[0060] Thus, the purified carbon dioxide gas exiting the purification assembly 500 can be at least 99.9% pure by volume, with a dew point equivalent less than or equal to minus thirty degrees Fahrenheit and/or a moisture content no greater than twenty parts per million. As such, this purified carbon dioxide gas may meet or exceed the beverage-grade standard for carbon dioxide set forth by the International Society of Beverage Technologists ("ISBT"). It should be understood that the purification assembly 500 and/or other components of the system 10 may be configured to meet other purity standards for carbon dioxide gas.

[0061] Referring to FIGS. 11 and 20, in the illustrated embodiment, the second intermediate storage assembly 600 accumulates and temporarily stores the purified carbon dioxide gas exiting the purification assembly 500 (FIG. 11). Thus, the second intermediate storage assembly 600 acts as a flow rate buffer and may also inhibit the formation of negative pressure in the upstream components. The controller 1000 continuously or incrementally monitors the second pressure sensor 630 to determine when the second storage vessel 625 reaches capacity at step S300 (FIG. 20). When the second pressure switch or sensor 630 indicates that the vessel 625 is full (or reaches a desired fullness), the controller 1000 sends a signal to open the output valve 620 at step S305. The controller 1000 initializes a condenser cooling control routine 1100 (FIG. 21) at step S310, then activates the compressor 705 at step S315 (FIG. 20). The compressor 705 draws carbon dioxide gas out of the second storage vessel 625. After a predetermined time period or in response to feedback from the second pressure sensor 630, the controller 1000 deactivates the compressor 705 at step S330, closes the output valve 620 at step S320, and optionally ends the condenser cooling control routine 1100 at step S325. Alternatively, if the second pressure sensor 630 includes a switch directly connected to the output valve 620 and the compressor 705, actuation of the switch may actuate the output valve 620 and activate or deactivate the compressor 705 without requiring communication with the controller 1000.

[0062] When operating, the compressor 705 compresses the carbon dioxide gas to a saturation point for carbon dioxide, preferably at a discharge pressure of at least 500 psi. In some embodiments, the compressor 705 compresses the carbon dioxide gas to a discharge pressure of at least 700 psi. In some embodiments, the compressor 705 compresses the gas to a pressure greater than the critical pressure point of carbon dioxide, which is 1,078 psi. In some embodiments, the compressor 705 compresses the gas to a pressure of at least 1,200 psi. In other embodiments, the compressor 705 compresses the gas to a pressure of at least 1,300 psi. In other embodiments, the compressor 705 compresses the gas to a pressure of at least 1,400 psi. In other embodiments, the compressor 705 compresses the gas to a pressure of at least 1,500 psi. In other embodiments, the compressor 705 compresses the gas to a pressure of at least 1,750 psi. In other embodiments, the compressor 705 compresses the gas to a pressure of at least 2,000 psi.

[0063] In some embodiments, the compressor 705 discharges carbon dioxide into the condenser assembly 800 (or aftercooler of the compressor 705) at a rate of about 0.2 cubic feet per minute or less. In some embodiments, the compressor 705 discharges carbon dioxide at a rate of about at a rate of about 0.3 cubic feet per minute or less. In some embodiments, the compressor 705 discharges carbon dioxide at a rate of about 0.4 cubic feet per minute or less. In some embodiments, the compressor 705 discharges carbon dioxide at a rate of about 0.5 cubic feet per minute or less. In some embodiments, the compressor 705 discharges carbon dioxide at a rate of about 1.0 cubic feet per minute or less. In other embodiments, the compressor 705 discharges carbon dioxide at a rate of about 5.0 cubic feet per minute or less. In other embodiments, the compressor 705 discharges carbon dioxide at a rate of about 11 cubic feet per minute or less. In other embodiments, the compressor 705 discharges carbon dioxide at a rate between about 0.2 cubic feet per minute and about 11 cubic feet per minute. Alternatively, compressor 705 may produce higher flow rates. In some embodiments, multiple compressors 705 may be provided in parallel or otherwise arranged to produce higher flow rates (e.g., up to 1,000 cubic feet per minute, in some embodiments).

[0064] The high pressure carbon dioxide leaves the compressor 705 and, in the illustrated embodiment, enters the condenser assembly 800 (FIG. 13). The carbon dioxide travels through the heat transfer coil 820 where it is cooled by transferring heat into the cooling medium surrounding the coil 820. This causes at least a portion of the gas to liquefy. In some embodiments, the carbon dioxide is cooled below its critical temperature (i.e. 87.98 degrees Fahrenheit).

[0065] Because carbon dioxide will liquefy at a relatively high temperature when pressurized to a relatively high pressure, the cooling medium of the condenser assembly 800 need not be at freezing or cryogenic temperatures. Accordingly, a more costly or more complex cooling system is not required. In the illustrated embodiment, the cooling medium has a temperature at the outlet 835 not less than 0 degrees Fahrenheit (FIG. 13). In some embodiments, the cooling medium has a temperature at the outlet 835 not less than 32 degrees Fahrenheit. In some embodiments, the cooling medium has a temperature at the outlet 835 not less than 40 degrees Fahrenheit. In some embodiments, the cooling medium has a temperature at the outlet 835 not less than 45 degrees Fahrenheit. In some embodiments, the cooling medium has a temperature at the outlet 835 not less than 50 degrees Fahrenheit. In some embodiments, the cooling medium has a temperature at the outlet 835 not less than 55 degrees Fahrenheit. In some embodiments, the cooling medium has a temperature at the outlet 835 not less than 60 degrees Fahrenheit. In some embodiments, the cooling medium has a temperature at the outlet 835 not less than 65 degrees Fahrenheit.

[0066] While gas is flowing into the condenser assembly 800, the controller 1000

continuously or incrementally monitors the temperature sensor 840 at step S400 to determine whether the cooling medium is at a proper cooling temperature (FIGS. 13 and 21). The controller compares the measured temperature with a predetermined temperature value at step S405. In some embodiments, the predetermined temperature value is about sixty degrees Fahrenheit. If the measured temperature is greater than the predetermined temperature, then the controller 1000 sends a signal to open the cooling valve at step S410. If the measured temperature is less than the predetermined temperature, then the controller 1000 sends a signal to close the cooling valve at step 415.

[0067] With reference to FIG. 14, liquid carbon dioxide or a mixture of gaseous and liquid carbon dioxide exits the condenser assembly 800 (or the aftercooler of the compressor assembly 700 if the condenser assembly 800 is omitted) at a pressure between about 500 psi and about 1,000 psi. The carbon dioxide enters the storage assembly 900 where it can be stored for future use. In the illustrated embodiment, the carbon dioxide is further cooled within the storage cylinders 905. Cooling fluid flows through the cylinder coolers 920 to cool the outer circumference of the storage cylinders 905, which in turn cools the carbon dioxide within the cylinders 905. Accordingly, when the pressure of carbon dioxide within the cylinders 905 exceeds about 700 psi (e.g., 750 psi), further cooling (e.g., by operation of the cylinder coolers 920) may cause at least a portion of the carbon dioxide contained within the cylinders 905 to liquefy as the intersection of pressure and temperature nears the saturation line for carbon dioxide.

[0068] In some embodiments, the cooling fluid is about 40 degrees Fahrenheit when it enters the cylinder coolers 920. In other embodiments, the cooling fluid is between about 40 degrees and about 60 degrees Fahrenheit. In other embodiments, the cooling fluid is between about 40 degrees and about 75 degrees Fahrenheit. The carbon dioxide is preferably stored in the cylinders 905 at a pressure between about 0 psi and about 1200 psi and a temperature between about 40 degrees and about 95 degrees Fahrenheit.

[0069] The compressor 705 may operate in an incremental or non-continuous manner to reduce heating of the cylinders 905. This may be particularly advantageous in embodiments of the storage assembly 900 in which the cylinder coolers 920 are omitted. For example, the compressor 705 may operate for about 35 seconds of a four minute time period. In other words, the compressor 705 may operate at a duty cycle of about 14.6%. By operating the compressor 705 in relatively short intervals, the cylinders 905 may be air cooled while still maintaining conditions at or near the saturation line 1115 (FIG. 22) for carbon dioxide.

[0070] FIG. 22 illustrates one embodiment of the liquefaction process carried out by the system 10 on a pressure-temperature phase diagram. In the illustrated embodiment, because the compressor 705 compresses the carbon dioxide gas to a pressure and temperature point A that is beyond the critical point 1105 for carbon dioxide, the carbon dioxide changes phase from a vapor into a supercritical fluid. The supercritical fluid is then cooled by the condenser assembly 800 and/or the cylinder coolers 920 along a path 1120 to a temperature below the critical

temperature. That cooling causes the carbon dioxide to cross a phase change line 1110 and change phase from a supercritical fluid into a liquid. As this phase change occurs, the carbon dioxide becomes denser, which leads to a lower pressure at a given volume. Alternatively, the compressor 705 may compress the carbon dioxide gas to any other pressure and temperature point that is at or above the saturation line 1115, between the critical point 1105 and the triple point 1125. Cooling the carbon dioxide from a pressure and temperature point on the saturation line 1115 will cause at least a portion of the carbon dioxide to liquefy.

[0071] In some embodiments, the pressure and temperature of the storage cylinders 905 may be controlled such that the stored carbon dioxide is kept at a temperature and pressure near the saturation line 1115 for carbon dioxide such that at least a portion of the stored carbon dioxide is maintained in its liquid phase. Because at least a portion of the carbon dioxide is liquid, a greater mass of carbon dioxide can be stored in the tanks 905 at a relatively lower pressure. The carbon dioxide may be stored in the cylinders 905 at a pressure and temperature point B that is above the saturation line 1115 such that the carbon dioxide remains in a predominantly liquid state.

[0072] The liquefaction process illustrated in FIG. 22 advantageously can occur at relatively high temperatures. Accordingly, a more complex and costly cooling system is not required. In contrast, other liquefaction processes require cooling carbon dioxide to significantly lower temperatures to initiate a phase change proximate the triple point 1125.

[0073] Thus, the system 10 captures raw carbon dioxide gas generated as a byproduct of a fermentation process, purifies the carbon dioxide to meet IB ST beverage grade standards, and liquefies at least some of the purified carbon dioxide gas to facilitate storage.

[0074] Various features of the disclosure are set forth in the following claims.