GB2562301A

GB2562301A - Cryogen system, apparatus and method of providing a cryogen under pressure for sanitising a carcass

Info

Publication number: GB2562301A
Application number: GB1707635.7A
Authority: GB
Inventors: Hipkin Richard
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2017-05-12
Filing date: 2017-05-12
Publication date: 2018-11-14
Anticipated expiration: 2037-05-12
Also published as: GB201707635D0; GB2562301B

Abstract

A cryogen driving system comprise a cryogen drain port (112, fig 2) and a first self-pressurising gravity-fed cryogen storage unit 118 for receiving a cryogen and is in fluid communication with the drain port. A second self-pressurising gravity-fed cryogen storage unit 120 for receiving the cryogen in fluid communication with the drain port. The drain port may be in communication with separate inlet ports 114, 116 that respectively feed the storage units. The first and second storage units respectively alternate between a filling and a purging state. The first and second storage units may be in fluid communication with a pressurizing unit 126 which may be pumpless and may be a vaporiser that uses cryogen from the storage units to pressurise said storage units. A flow controller (202, fig 3) may be used to toggle between the alternating filling and purging of the first and second storage units using valves 122, 124. Inhibiting the filling of one tank occurs when it contains a predetermined level of cryogen. A related method of sanitising a carcass and apparatus using the above system are also provided.

Description

CRYOGEN SYSTEM, APPARATUS AND METHOD OF PROVIDING A CRYOGEN UNDER PRESSURE FOR SANITISING A CARCASS

[0001] The present invention relates to a cryogen system of the type that, for example, expels a cryogen received at an inlet port out through an outlet port under pressure. The present invention also relates to a cryogen application apparatus for sanitising a carcass, the apparatus being of the type that, for example, comprises the cryogen system. The present invention further relates to a method of driving a cryogen, the method being of the type that, for example, expels a cryogen received at an inlet port out through an outlet port under pressure.

[0002] In some cryogenic supply systems, it is desirable to pump a cryogen from a source location to a destination. For example, in an apparatus for sanitising a carcass, for example but not exclusively a poultry carcass, it is known to provide a passageway into which a cryogen is ejected from an array of nozzles. Poultry carcasses are translated through the passageway, during which time some of the cryogen ejected from the nozzles impinges upon the carcass in order to reduce a population of bacteria, for example a species of bacteria, such as Campylobacter jejuni.

[0003] The apparatus is typically operating for a large proportion of a day over several days, during which a considerable amount of cryogen is used. The passageway has a floor onto which some of the cryogen falls. For economic reasons, it is desirable to recover as much of the liquid cryogen that falls to the floor, possibly for re-use. In this respect, one technique for recovering the cryogen from the floor of the passageway is to employ a pump. However, pumps sufficiently resilient to pump the cryogen are expensive and have a, relatively short, finite lifespan. It is therefore necessary to have at least one additional cryogen pump on standby in case a cryogen pump in use in the apparatus fails, because halting operation of the apparatus for a prolonged period of time for repair has adverse economic implications. Given that such pumps are expensive, the need for multiple pumps simply further increases the cost of providing and operating the apparatus.

[0004] According to a first aspect (embodiment) of the present invention, there is provided a cryogen driving system comprising: a cryogen inlet port; a first selfpressurising gravity-fed cryogen storage unit for receiving a cryogen and being in fluid communication with the cryogen inlet port; a second self-pressurising gravity-fed cryogen storage unit for receiving the cryogen and being in fluid communication with the cryogen inlet port; wherein the first and second cryogen storage units are respectively arranged to alternate between a filling state and a purging state.

[0005] According to a second aspect (embodiment) of the invention, there is provided a cryogen system for sanitising a carcass comprising: a cryogen inlet port; a first self-pressurising gravity-fed cryogen storage unit for receiving a cryogen and being in fluid communication with the cryogen inlet port; a second self-pressurising gravity-fed cryogen storage unit for receiving the cryogen and being in fluid communication with the cryogen inlet port; wherein the first and second cryogen storage units coact with the cryogen inlet port to alternate between a filling state and a purging state.

[0006] The self-pressurising gravity-fed cryogen storage unit may be arranged to use, when in use, received cryogen to provide pressurisation.

[0007] The received cryogen may be recovered cryogen, for example liquid cryogen. The cryogen may be, for example, liquid nitrogen (LIN).

[0008] The first self-pressurising gravity-fed cryogen storage unit may be arranged to purge cryogen therefrom, when in use, at least in part when a predetermined quantity of cryogen has been received and a predetermined pressurisation of the cryogen has been achieved.

[0009] The system may further comprise: a pressurising unit in fluid communication with the first gravity-fed cryogen storage unit.

[0010] The pressurising unit may be pumpless. The pressurising unit may be a vaporiser. The vaporiser may be an ambient vaporiser.

[0011] The system may further comprise: a cryogen drain port selectively in fluid communication with the first self-pressurising gravity-fed cryogen storage unit; and a flow controller operably coupled between the cryogen drain port and the inlet port of the first self-pressurising gravity-fed cryogen storage unit in order to inhibit filling of the first self-pressurising gravity-fed cryogen storage unit selectively once the first self-pressurising gravity-fed cryogen storage unit is filled to a predetermined level.

[0012] The system may further comprise: a pressure valve operably coupled between the first self-pressurising gravity-fed cryogen storage unit and the pressurising unit; the pressure valve may be arranged to open in response to a predetermined pressure criterion.

[0013] The predetermined pressure criterion may be a pressure equal to and/or below a predetermined pressure.

[0014] The pressurising unit may be arranged to use, when in use, cryogen provided from the first self-pressurising gravity-fed cryogen storage unit to pressurise the first self-pressurising gravity-fed cryogen storage unit.

[0015] The first self-pressurising gravity-fed cryogen storage unit may comprise an outlet port for purging pressurised cryogen therefrom.

[0016] The system may further comprise a pressure dependent flow control device, for example a valve, operably coupled to the outlet port; the flow control device may be arranged to permit passage of the received cryogen therethrough in response to a predetermined purge pressure being attained within the first selfpressurising gravity-fed cryogen storage unit.

[0017] The second self-pressurising gravity-fed cryogen storage unit has another inlet port and another outlet port.

[0018] The flow controller may be operably coupled to the another inlet port; and the flow controller may be arranged to toggle between coupling the cryogen drain port to the first self-pressurising gravity-fed cryogen storage unit and the second self-pressurising gravity-fed cryogen storage unit.

[0019] The toggling between the first self-pressurising gravity-fed cryogen storage unit and the second self-pressurising gravity-fed cryogen storage unit may be alternately in response to alternate filling and purging of the first selfpressurising gravity-fed cryogen storage unit and the second self-pressurising gravity-fed cryogen storage unit.

[0020] The flow controller may comprise electronically actuatable devices and toggles fluid communication between the cryogen drain port and the first selfpressurising gravity-fed cryogen storage unit and the second self-pressurising gravity-fed cryogen storage unit in response to a control signal.

[0021] The control signal may be generated in response to the first selfpressurising gravity-fed cryogen storage unit being filled to the predetermined level. The control signal may be generated in response to the second selfpressurising gravity-fed cryogen storage unit being filled to another predetermined level.

[0022] The pressurising unit may be in fluid communication with the second selfpressurising gravity-fed cryogen storage unit.

[0023] The another second self-pressurising gravity-fed cryogen storage unit may comprise another pressure valve operably coupled between the second selfpressurising gravity-fed cryogen storage unit and the pressurising unit; the another pressure valve may be arranged to open in response to the predetermined pressure criterion.

[0024] The pressurising unit may be arranged to use, when in use, cryogen provided from the second self-pressurising gravity-fed cryogen storage unit to pressurise the second self-pressurising gravity-fed cryogen storage unit.

[0025] The second self-pressurising gravity-fed cryogen storage unit may be arranged to purge, when in use, received cryogen stored therein via the another outlet port.

[0026] The system may further comprise another pressure dependent flow control device, for example another valve, operably coupled to the another outlet port; the another flow control device may be arranged to permit passage of the received cryogen therethrough in response to another predetermined purge pressure being attained within the second self-pressurising gravity-fed cryogen storage unit.

[0027] According to a third aspect (embodiment) of the present invention, there is provided a cryogen application apparatus for sanitising a carcass, the apparatus comprising: a passageway having a floor and arranged to expel a cryogen therein for sanitising a carcass passing therethrough; and the system as set forth above in relation to the first or second aspects of the invention, the cryogen drain port being in fluid communication with the floor of the passageway.

[0028] According to a fourth aspect (embodiment) of the present invention, there is provided a method of providing a cryogen under pressure for sanitising a carcass, the method comprising: receiving a cryogen fed under gravity; using a portion of the received cryogen to pressurise a pressure vessel containing the received cryogen; and purging the received cryogen under pressure from the pressure vessel under pressure by virtue of the self-pressurisation of the pressure vessel.

[0029] It is thus possible to provide system, apparatus and method embodiments that obviate the need to use a cryogenic pump to expel a cryogen received at an inlet port out through an outlet port. The embodiments are of simpler construction and operation than the cryogenic pump and requires fewer moving parts. The embodiments also possess a greater longevity than the cryogenic pump. Consequently, the system, apparatus and method embodiments serve to reduce the cost of other systems and apparatus in which the cryogen system, apparatus and method embodiments are provided where a cryogenic pump would otherwise be required.

[0030] At least one embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [0031] Figure 1 is a schematic plan elevation of a cryogen application apparatus comprising a driving system constituting an embodiment of the invention; [0032] Figure 2 is a schematic side elevation of the cryogen application apparatus of Figure 1; [0033] Figure 3 is a schematic diagram of a flow controller used in the driving system of Figures 1 and 2; and [0034] Figure 4 is a flow diagram of a method of driving a cryogen constituting another embodiment of the invention.

[0035] Referring to Figures 1 and 2, a cryogen application apparatus 100 comprises a passageway 102 or tunnel comprising a spray bar 104 carrying an array of outlet nozzles 106 for dispensing a cryogen, the spray bar 104 and array of nozzles 106 being in fluid communication with a main cryogen supply system (not shown) via a manifold conduit 107 and a control valve 108. The passageway 102 comprises a floor 110, which in this example is sloped towards a drain port 112. The drain port 112 is in fluid communication with a first inlet port 114 and a second inlet port 116 of a cryogen driving system.

[0036] The cryogen driving system also comprises a first cryogen storage tank 118 and a second cryogen storage tank 120 constituting first and second pressure vessels. The first and second cryogen storage tanks 118, 120 can each contain and use, for example, liquid nitrogen (LIN). The first cryogen storage tank 118 is in fluid communication with the first inlet port 114 via a first inlet control valve 122 of a flow controller. The second cryogen storage tank 120 is in fluid communication with the second inlet port 116 via a second inlet control valve 124. A pressurisation unit, for example a vaporiser 126, is in fluid communication with the first storage tank 118 and the second storage tank 120. In this regard, a first cryogen feed fluid conduit 128 provides fluid communication between a first pressurisation outlet port of the first tank 118 and a first inlet port of the vaporiser 126 via a first pressure control valve 130, and a second cryogen feed fluid conduit 132 provides fluid communication between a second pressurisation outlet port of the second tank 120 and a second inlet port of the vaporiser 126 via a second pressure control valve 134. In this example, the first and second pressure control valves 130, 134 are so-called pressure build-up cash valves. An outlet port of the vaporiser 126 is in fluid communication with a first vapour inlet port of the first tank 118 and a second vapour inlet port of the second tank 120 via a first pressurisation isolation valve 136 and a second pressurisation isolation valve 138, respectively. In some examples, the first and second pressurisation isolation valves 134, 136 are optional.

[0037] A fluid conduit return network 140 comprises a first return branch 142 and a second return branch 144. The first return branch 142 is in fluid communication at a first end thereof with the first tank 118 via a first tank outlet valve 146. Similarly, the second return branch 144 is in fluid communication at a first end thereof with the second tank 120 via a second tank outlet valve 148. The fluid conduit return network 140 also comprises a common return fluid conduit 150 that is in fluid communication at one end thereof with respective second ends of the first and second return branches 142, 144. A second end of the common return fluid conduit 150 is in fluid communication with the manifold conduit 107 that fluidly communicates the spray bar 104 with the main cryogen supply system. In this example, the second end of the common return fluid conduit 150 is in fluid communication with the manifold conduit 107 via a pressure relief valve 154, the connection between the common return fluid conduit 150 and the manifold conduit 107 effectively constituting, in this example, a cryogen inlet port. A relatively small bore vent conduit 155 branches off and is in fluid communication with the common return fluid conduit 150, for example before the pressure relief valve 154, so that the pressure relief valve 154 is disposed between the vent conduit 155 and the manifold conduit 152, such as adjacent the pressure relief valve 154. The vent conduit 155 serves to allow cryogen vapour present in the liquid phase cryogen to vent. The pressure relief valve 154 is set, in this example at a pressure exceeding the expected pressure in the manifold conduit 107.

[0038] A first cryogen level sensor 156 is operably coupled to the first tank 118 and a second cryogen level sensor 158 is operably coupled to the second tank 120.

[0039] Referring to Figure 3, a flow controller 200 comprises, in this example, a microcontroller 202 operably coupled to a valve driver unit 204 via a command and control bus 206. The first cryogen level sensor 156 and the second cryogen level sensor 158 are also operably coupled to the microcontroller 202. In this example, the first inlet control valve 122, the second inlet control valve 124, the first pressurisation isolation valve 136, the second pressurisation isolation valve 138, the first tank outlet valve 146 and the second tank outlet valve 148 are respectively operably coupled to the valve driver unit 204.

[0040] In operation and referring to Figure 4, upon powering up, the controller 202 selects the first tank 118 as being “online” and to be filled with recovered cryogen. The second tank 120 is “offline”. The controller 202 closes the second inlet control valve 124, the second pressurisation isolation valve 138 and the first tank outlet valve 146, while the controller 202 opens the first inlet control valve 122, the first pressurisation isolation valve 136 and the second tank outlet valve 148. The main cryogen supply system also initiates supply of a cryogen, for example nitrogen, in liquid phase to the spray bar 104 via the manifold conduit 152. Cryogen is therefore ejected from the array of outlet nozzles 106 into the passageway 102. Carcasses of, for example, poultry are then conveyed through the passageway 102 via a separate conveyor system (not shown). As the details of the main cryogen supply system and the conveyor system are not core to an understanding of the cryogen driving system, the main cryogen supply system and the conveyor system will not be described in further detail herein.

[0041] During operation of the cryogen application apparatus, a proportion of the cryogen ejected from the array of nozzles 106 is applied to the carcasses passing through the passageway 102. However, another proportion of the cryogen either falls directly to the floor 110 or rebounds off the carcasses and falls to the floor 110. Due to the slope of the floor 110, the cryogen landing on the floor in liquid phase runs down the slope of the floor to the drain port 112.

[0042] The cryogen collecting at the drain port 112 flows through the first inlet port 114 to the first tank 118 via the open first inlet control valve 122 (Step 300), but not into the second tank 120, because the second inlet control valve 124 is closed. The cryogen is therefore gravity fed into the first tank 118 and therefore recovered. The controller 202 monitors signals generated by the first cryogen level sensor 156 in order to determine the level of cryogen contained in the first tank 118. In this respect, when the first tank 118 reaches, in this example 75% full (Step 302), the controller 202 initiates a switching (Step 304) of the tanks used to collect the cryogen flowing into the drain port 112. In this regard, when the desired level of cryogen in the online tank is attained, the controller 202 closes the first inlet control valve 122 and opens the second inlet control valve 124 in order to take the first tank 118 offline and bring the second tank 120 online, thereby preventing further filling of the first tank 118, but enabling filling of the second tank 120. The controller 202 then determines whether an “offline” tank, in this example now the first tank 118, is to be purged (Step 306). In this regard, the controller 202 determines, due to the level of cryogen in the first tank 118, that the first tank 118 is to be purged and so the controller 202 closes (Step 308) the second pressurisation isolation valve 138 and opens the first pressurisation isolation valve 136.

[0043] Since the pressure in the first tank 118 is below the minimum pressure threshold set by the first pressure control valve 130, the first pressure control valve 130 is open (Step 310) and allows cryogen to flow into the vaporiser 126, which is an ambient vaporiser in this example. The cryogen entering the vaporiser 126 boils at ambient temperature and so changes to a vapour phase before leaving the vaporiser 126 and passing back into the first tank 118 via the first pressurisation isolation valve 136. The vapour returning to the first tank 118 serves to pressurise the first tank 118 and so the cryogen driving system can be considered to be self pressurising. In this respect, the first pressure control valve 130 remains open until the pressure within the first tank 118 reaches the predetermined pressure, which in this example is 3 bar.

[0044] The controller also closes the second tank outlet valve 148 and opens (Step 312) the first tank outlet valve 146, allowing the now pressurised cryogen stored in the first tank 118 to exit under pressure and therefore be driven (Step 314) through the first return branch conduit 142 to the common return fluid conduit 150, where when the pressure of the pressurised cryogen exceeds the pressure of the main cryogen supply system, overcomes the pressure relief valve 154 and flows into the manifold conduit 107. Consequently, the pressurised cryogen is ejected from the array of outlet nozzles 106. When the pressure of the pressurised cryogen in the common return fluid conduit 150 is insufficient to overcome the pressure relief valve 154, the cryogen from the cryogen supply system takes over satisfying the cryogen supply requirements of cryogen application apparatus 100.

[0045] Throughout this purging process, the controller 202 monitors the level of cryogen in the first tank 118 in order to determined when the cryogen stored in the first tank 118 has been substantially depleted. Also, during the purging process, as the pressure within the first tank 118 drops, the first pressure control valve 130 reopens and allows cryogen to enter the vaporiser 126 for evaporation and reintroduction into the first tank 118 so as to re-pressurise the first tank 118. However, once the first tank 118 has been determined (Step 316) to be purged, the controller 202 returns to determining (Step 306) whether an offline tank needs to be purged. In this respect, since the first tank 118 has been purged, no further purging is necessary and the second tank 120 is an online tank and so is not eligible for purging.

[0046] The controller 202 also monitors signals generated by the second cryogen level sensor 158 in order to determine the level of cryogen contained in the second tank 120. In this respect, when the second tank 120 reaches, in this example 75% full, the controller 202 initiates another switching (Step 304) of the tanks used to collect the cryogen flowing into the drain port 112. As such, the controller 202 closes the second inlet control valve 124 and opens the first inlet control valve 122. The controller 202 also closes the first tank outlet valve 146 and opens the second tank outlet valve 148, as well as opening the second pressure isolation valve 138 and closing the first pressure isolation valve 138. As such, the first tank 118 becomes the online tank and the second tank 120 becomes the offline tank. The purging process described above in relation to the first tank 118 is then preformed but in respect of the second tank 120 while the first tank 118 is filled under gravity with cryogen.

[0047] The above toggling or alternating between the first and second tanks 118, 120 is repeated as each tank becomes full and the counterpart tank becomes depleted.

[0048] The skilled person should appreciate that the above-described embodiments are merely examples of the various implementations that are conceivable within the scope of the appended claims. Indeed, although in the above example the first and second pressure isolation valves 136, 138 are provided, these valves are optional. Also, the first and second pressure control valves 130, 134 need not be disposed before the respective inlets to the vaporiser 126 and can be disposed in place of the first and second pressure isolation valves 130, 134.

[0049] Although in the above examples, the array of outlet nozzles 106 is described as being in a particular configuration with respect to the spray bar 104 and the manifold conduit 107, the skilled person should appreciate that other configurations of nozzles are intended. Furthermore, the above exemplary cryogen driving system and method is not solely applicable to the application apparatus described above, and the system can be used for any other suitable application where it is desirable to drive a cryogen.

[0050] Although the above examples have been described in the context of liquid nitrogen, the skilled person should appreciate that other cryogens can be employed.

Claims

1. A cryogen driving system comprising: a cryogen inlet port; a first self-pressurising gravity-fed cryogen storage unit for receiving a cryogen and being in fluid communication with the cryogen inlet port; a second self-pressurising gravity-fed cryogen storage unit for receiving the cryogen and being in fluid communication with the cryogen inlet port; wherein the first and second cryogen storage units are respectively arranged to alternate between a filling state and a purging state.

2. A system as claimed in Claim 1, wherein the first self-pressurising gravity-fed cryogen storage unit is arranged to use, when in use, received cryogen to provide pressurisation.

3. A system as claimed in Claim 1 or Claim 2, wherein the first selfpressurising gravity-fed cryogen storage unit is arranged to purge cryogen therefrom, when in use, at least in part when a predetermined quantity of cryogen has been received and a predetermined pressurisation of the cryogen has been achieved.

4. A system as claimed in Claim 1 or Claim 2 or Claim 3, further comprising: a pressurising unit in fluid communication with the first self-pressuring gravity-fed cryogen storage unit.

5. A system as claimed in Claim 4, wherein the pressurising unit is pumpless.

6. A system as claimed in Claim 4 or Claim 5, wherein the pressurising unit is a vaporiser.

7. A system as claimed in Claim 4 or Claim 5 or Claim 6, further comprising: a cryogen drain port selectively in fluid communication with the first selfpressurising gravity-fed cryogen storage unit; and a flow controller operably coupled between the cryogen drain port and the inlet port of the first self-pressurising gravity-fed cryogen storage unit in order to inhibit filling of the first self-pressurising gravity-fed cryogen storage unit selectively once the first self-pressurising gravity-fed cryogen storage unit is filled to a predetermined level.

8. A system as claimed in any one of Claims 4 to 7, further comprising: a pressure valve operably coupled between the first self-pressurising gravity-fed cryogen storage unit and the pressurising unit, the pressure valve being arranged to open in response to a predetermined pressure criterion.

9. A system as claimed in any one of Claims 4 to 8, wherein the pressurising unit is arranged to use, when in use, cryogen provided from the first selfpressurising gravity-fed cryogen storage unit to pressurise the first selfpressurising gravity-fed cryogen storage unit.

10. A system as claimed in any one of Claims 4 to 9, wherein the first selfpressurising gravity-fed cryogen storage unit comprises an outlet port for purging pressurised cryogen therefrom.

11. A system as claimed in any one of Claims 4 to 10, wherein: the second self-pressurising gravity-fed cryogen storage unit has another inlet port and another outlet port.

12. A system as claimed in Claim 11, when dependent upon Claim 7, wherein the flow controller is operably coupled to the another inlet port; and the flow controller is arranged to toggle between coupling the cryogen drain port to the first self-pressurising gravity-fed cryogen storage unit and the second self-pressurising gravity-fed cryogen storage unit.

13. A system as claimed in Claim 12, wherein the flow controller comprises electronically actuatable devices and toggles fluid communication between the cryogen drain port and the first self-pressurising gravity-fed cryogen storage unit and the second self-pressurising gravity-fed cryogen storage unit in response to a control signal.

14. A system as claimed in Claim 11 or Claim 12 or Claim 13, wherein the pressurising unit is in fluid communication with the second self-pressurising gravity-fed cryogen storage unit.

15. A system as claimed in Claim 14, when dependent upon Claim 8, wherein the second self-pressurising gravity-fed cryogen storage unit comprises another pressure valve operably coupled between the second self-pressurising gravity-fed cryogen storage unit and the pressurising unit, the another pressure valve being arranged to open in response to the predetermined pressure criterion.

16. A system as claimed in Claim 14, wherein the pressurising unit is arranged to use, when in use, cryogen provided from the second self-pressurising gravity-fed cryogen storage unit to pressurise the second self-pressurising gravity-fed cryogen storage unit.

17. A system as claimed in any one of Claims 11 to 16, wherein the second self-pressurising gravity-fed cryogen storage unit is arranged to purge, when in use, received cryogen stored therein via the another outlet port.

18. A cryogen application apparatus for sanitising a carcass, the apparatus comprising: a passageway having a floor and arranged to expel a cryogen into the passageway for contacting and sanitising a carcass passing therethrough; and the system as claimed in any one of the preceding claims, the cryogen drain port being in fluid communication with the floor of the passageway.

19. A method of providing a cryogen under pressure for sanitising a carcass, the method comprising: receiving a cryogen fed under gravity; using a portion of the received cryogen to pressurise a pressure vessel containing the received cryogen; and purging the received cryogen under pressure from the pressure vessel under pressure by virtue of the self-pressurisation of the pressure vessel.