GB2553098A

GB2553098A - System and method for monitoring the atmosphere of a controlled atmosphere workstation

Info

Publication number: GB2553098A
Application number: GB1614174.9A
Authority: GB
Inventors: Charles Roper Christopher; Boast David
Original assignee: Don Whitley Scientific Ltd
Current assignee: Don Whitley Scientific Ltd
Priority date: 2016-08-18
Filing date: 2016-08-18
Publication date: 2018-02-28
Anticipated expiration: 2036-08-18
Also published as: GB2553098B; GB201614174D0

Abstract

A system for monitoring the atmosphere in a chamber of a controlled atmosphere workstation, the system comprising a first gas sensor 4 to detect a first gas in the atmosphere, a protector 8 to shield the first gas sensor from one or more degrading products and a controller 5 to process the gas data of the first gas sensor and determine the concentration of the first gas in the atmosphere based on the gas data. The controller may control a supply of first gas to the chamber in accordance with the determined concentration of the first gas. Optionally, prior to determining the concentration of the first gas, the controller corrects distortion errors in the gas data due to one or more distorting gases in the atmosphere. The protector may be an enclosure or housing with gas inlet 9 and gas outlet 10 which protects the gas sensor. Ideally, the gas sensor is positioned in the base of the workstation which comprises a floor partition 13. A workstation comprising the system and a method of operation is also disclosed.

Description

(54) Title of the Invention: System and method for monitoring the atmosphere of a controlled atmosphere workstation

Abstract Title: A system and method for monitoring the atmosphere of a controlled Atmosphere workstation (57) A system for monitoring the atmosphere in a chamber of a controlled atmosphere workstation, the system comprising a first gas sensor 4 to detect a first gas in the atmosphere, a protector 8 to shield the first gas sensor from one or more degrading products and a controller 5 to process the gas data of the first gas sensor and determine the concentration of the first gas in the atmosphere based on the gas data. The controller may control a supply of first gas to the chamber in accordance with the determined concentration of the first gas. Optionally, prior to determining the concentration of the first gas, the controller corrects distortion errors in the gas data due to one or more distorting gases in the atmosphere. The protector may be an enclosure or housing with gas inlet 9 and gas outlet 10 which protects the gas sensor. Ideally, the gas sensor is positioned in the base of the workstation which comprises a floor partition 13. A workstation comprising the system and a method of operation is also disclosed.

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SYSTEM AND METHOD FOR MONITORING THE ATMOSPHERE OF A CONTROLLED ATMOSPHERE WORKSTATION

FIELD OF THE INVENTION [01] The present invention relates to a controlled atmosphere workstation. In particular, the invention relates to a system and method for monitoring the atmosphere of a controlled atmosphere workstation.

BACKGROUND OF THE INVENTION [02] A controlled atmosphere workstation provides a chamber with a controlled atmospheric working environment. The chamber atmosphere may be controlled to have a certain temperature, humidity, pressure and/or chemical composition. For example, a controlled atmosphere workstation may have a microaerophilic or anaerobic atmosphere, where oxygen concentration is controlled.

[03] Up to four gases - nitrogen, carbon dioxide, air and hydrogen - can be combined in varying ratios to provide a specific atmosphere in a workstation. For example, gases may be supplied to create a microaerophilic atmosphere comprising 3% hydrogen, 5% carbon dioxide, 5% oxygen and 87% nitrogen. Alternatively, gases may be supplied to create, for example, an anaerobic atmosphere comprising 10% hydrogen, 10% carbon dioxide and 80% nitrogen.

[04] Previously, the concentration of hydrogen gas in the atmosphere of the workstation has been monitored by using an independent hydrogen sensing system. However, it has been found that the accuracy of these sensing systems is limited because hydrogen sensors can be adversely affected by the presence of other gases in the atmosphere. Also, hydrogen sensors can degrade due to water vapour and by2 products generated in the chamber by microbiological processes. Moreover, the function of the sensing system is restricted to sensing and, typically, the supply of hydrogen gas is separately regulated based on a time/flow rate calculation.

SUMMARY OF THE INVENTION [05] Embodiments of the present invention seek to address and/or overcome one or more of the problems identified above. Embodiments of the present invention seek to provide an improved system and method for monitoring the atmosphere of a workstation. Embodiments of the present invention seek to more accurately determine the concentration of the chemical composition of the atmosphere of a workstation. Embodiments of the present invention seek to provide closed loop control of the chemical composition of the atmosphere of a workstation. Embodiments of the present invention seek to monitor the atmosphere by determining the concentration of a gas in the atmosphere and controlling the supply of the gas to the atmosphere in accordance with the determined concentration. As a result, the required concentration of the gas can be maintained in the atmosphere of the controlled atmosphere workstation.

[06] A first aspect of the invention relates to a system for monitoring the atmosphere in a chamber of a controlled atmosphere workstation.

[07] The system comprises:

a first gas sensor to detect for a first gas in the atmosphere; a protector to shield the first gas sensor from one or more degrading products; a controller to process the gas data of the first gas sensor and determine the concentration of the first gas in the atmosphere based on the gas data.

[08] The first gas sensor is arranged in the chamber, in the flow path of the atmosphere. The first gas sensor may be any suitable gas sensor for detecting a predetermined gas in the chamber atmosphere of the workstation. The first gas sensor may, for example, be a hydrogen sensor to detect for the presence or absence of hydrogen gas in the chamber atmosphere.

[09] During the operation of the workstation, one or more degrading products is typically generated in the chamber that can degrade the first gas sensor. The one or more degrading products depends on the operations conducted in the workstation, composition of the atmosphere and the type of first gas sensor. The degrading products may include, for example, a volatile fatty acid, hydrogen sulphide and/or water vapour. The protector is configured to restrict one or more degrading products from reaching the first gas sensor. By sheltering the gas sensor from one or more degrading products, the damaging effect of the one or more degrading products on the first gas sensor is mitigated. The first gas sensor can therefore safely remain in the workstation and monitor the chamber atmosphere whilst the workstation is operational and the performance of the first gas sensor is enhanced. As a result, the system allows for improved and continuous measuring of the first gas.

[10] The protector may comprise an enclosure in which the first gas sensor can be located. The enclosure is configured to substantially shroud the first gas sensor so as to shelter it from one or more degrading products in the chamber of the workstation. To allow the first gas sensor to detect the first gas in the atmosphere, the enclosure comprises an inlet and outlet to guide at least a portion of the atmosphere through the enclosure and across the first gas sensor. In an embodiment, the first gas sensor and enclosure may be arranged in the return flow path of the atmosphere and the enclosure may comprise an inlet and outlet to guide at least a portion of the return flow of the atmosphere through the enclosure and across the first gas sensor.

[11] The enclosure may be a housing, cavity, recess or any other suitable container.

[12] The protector may additionally or alternatively comprise a screen configured to set apart the gas sensor from a processing region of the chamber where work can be conducted and one or more degrading products may be generated. The screen is configured to define a sensing region of the chamber in which the first gas sensor is located. To allow the first gas sensor to detect the first gas in the atmosphere, the screen is further configured to define an inlet and outlet in the sensing region so as to guide at least a portion of the atmosphere through the sensing region of the chamber and across the first gas sensor. The screen is preferably configured to guide at least a portion of the return flow of the atmosphere through the sensing region of the chamber and across the first gas sensor.

[13] The screen may be a panel or any other suitable partition. The screen may be configured to form a false wall, ceiling or floor in the chamber of the workstation.

[14] The controller is configured to automate the measuring of the first gas, with limited or no operator intervention. As a result, the accuracy and speed of measuring the first gas is superior, the size of the chamber is unrestricted and the risk of humanerror is avoided.

[15] The controller may be configured to compare the determined concentration of the first gas in the chamber atmosphere relative to a required concentration of the first gas to determine if the determined concentration of the first gas is sufficient or is insufficient.

[16] To control the atmosphere of the workstation, the controller may be configured to control the supply of the first gas to the chamber. To provide closed loop control of the atmosphere, the controller may be configured to control the supply of the first gas to the chamber in accordance with the determined concentration of the first gas.

[17] One or more other gases in the chamber atmosphere can distort the gas detection of the first gas sensor and lead to the first gas sensor collecting erroneous gas data that does not accurately relate to the first gas. The one or more distorting gases depends on the chemical composition of the chamber atmosphere and the type of gas sensor. The distorting gases for a hydrogen sensor may include, for example carbon dioxide and/or oxygen. To compensate for the effect of one or more distorting gases on the first gas sensor, the controller may be configured to clean the gas data of the first gas sensor by correcting distortion errors in the gas data. By cleansing the gas data of the first gas sensor, the integrity of the gas data is improved and the concentration of the first predetermined gas is thereby more reliably determined.

[18] The controller may be configured to correct distortion errors in the gas data of the first gas sensor using a distortion adjustment representative of the distorting effect one or more distorting gas may have on the first gas sensor. In an embodiment, distortion adjustment is a predetermined distortion adjustment representative of the distorting effect one or more distorting gas expected to be in the chamber atmosphere will have on the first gas sensor. In an alternative embodiment providing real-time or near-real time control, the system may further comprise a distorting gas analyser to detect one or more distorting gases in the atmosphere and determine a distortion adjustment representative of the distorting effect the one or more detected distorting gases is having on the first gas sensor. The distorting gas analyser may comprise one or more distorting gas sensors to detect for one or more distorting gases and a distorting gas controller to process the gas data of the one or more distorting gas sensors and determine a distortion adjustment based on the distorting gas data. The controller may be configured to correct distortion errors in the gas data of the first gas sensor using the determined distortion adjustment.

[19] The system may comprise operator activation to initiate the monitoring of the atmosphere when actuated by the operator.

[20] The system may comprise a time lapse activation to automatically initiate the monitoring of the atmosphere after a predetermined time period or at predetermined intervals.

[21] The system may comprise an operator warning to alert the operator that monitoring of the atmosphere is required.

[22] The system may comprise an operator display configured to display the determined concentration of the first predetermined gas, display if the determined concentration of the first predetermined gas is sufficient and/or display if the determined concentration of the first predetermined gas is insufficient.

[23] A second aspect of the invention relates to a controlled atmosphere workstation comprising a chamber with a controlled atmosphere; and a system for monitoring the atmosphere in the chamber according to a first aspect of the invention.

[24] A third aspect of the invention relates to a method for monitoring the atmosphere in a chamber of a controlled atmosphere workstation.

[25] The method comprising:

sensing for a first gas in the atmosphere using a first gas sensor;

shielding the first gas sensor from one or more degrading products in the chamber; and processing the first gas data and determining the concentration of the first gas in the atmosphere based on the first gas data.

[26] The method may comprise guiding at least a portion of the atmosphere across the first gas sensor, preferably at least a portion of the return flow of the atmosphere.

[27] The method may comprise comparing the determined concentration of the first gas with a required concentration of the first gas or required concentration range of the first gas and determining if the determined concentration is sufficient or insufficient. To provide closed loop control, the method may comprise controlling a supply of first gas into the chamber atmosphere in accordance with the determined concentration of the first gas.

[28] The method may comprise cleansing the gas data of the first gas sensor, prior to determining the concentration of the first gas, so as to compensate for the distorting effects on the first gas sensor by one or more distorting gases in the atmosphere. The cleansing step may comprise correcting distortion errors in the gas data using a distortion adjustment. The method may comprise determining the distortion adjustment from gas data of one or more distorting gas sensors.

BRIEF DESCRIPTION OF THE DRAWINGS [29] Certain embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

[30] Figure 1 is a perspective view of a first embodiment of a workstation according to the invention;

[31] Figure 2 is a front view of the first embodiment of the workstation of Figure 1;

[32] Figure 3 is a cross-sectional view of the first embodiment of the workstation of Figure 1 showing an enclosure and floor panel to protect a hydrogen gas sensor from degrading products;

[33] Figure 4 is a cross-sectional view of a second embodiment of the workstation showing distorting gas sensors to detect carbon dioxide and oxygen.

DETAIFED DESCRIPTION OF THE INVENTION [34] Referring to Figures 1 and 2, there is shown in general terms a controlled atmosphere workstation 1 according to the present invention. The workstation has an internal working chamber 2 in which samples, products and/or devices can be held under specific atmospheric conditions and in which operations can be carried out. An operator can insert his arms into the working chamber through at least one porthole, preferably a pair of portholes 3a, 3b. The workstation is designed to provide a controlled atmosphere in the working chamber, as desired. To stabilise the controlled atmosphere throughout the working chamber, the workstation may comprise a fan to circulate the controlled atmosphere. For example, the controlled atmosphere A may be circulated in an anti-clockwise direction from the front to the rear of the working chamber as shown in Figures 3 and 4.

[35] In the embodiments depicted in Figures 1 to 4, the workstation comprises a supply of hydrogen gas (not shown) to provide hydrogen gas in the working chamber. To monitor the hydrogen gas in the atmosphere of the working chamber, the workstation comprises a hydrogen sensor 4. To automate the monitoring process, the workstation comprises a controller 5, in the form of a microprocessor with programmable logic, to control the sensing of the hydrogen sensor, process the hydrogen gas data of the hydrogen sensor and determine the concentration of hydrogen gas in the atmosphere based on the gas data. Hence, the concentration of hydrogen gas present in the controlled atmosphere can be automatically and continuously measured with minimal or no input from an operator.

[36] The required concentration of hydrogen gas is dependent on the desired controlled atmosphere of the workstation. The controller is configured to compare the measured concentration of hydrogen gas with respect to a required hydrogen gas concentration. If the measured concentration of hydrogen gas falls below the required concentration then the concentration of hydrogen gas is deemed to be insufficient to achieve the desired controlled atmosphere.

[37] To inform an operator, the workstation includes a display 6 configured to display the measured concentration of hydrogen gas, indicate if the concentration of hydrogen gas is sufficient and/or indicate if the concentration of hydrogen gas is insufficient.

[38] To allow an operator to initiate the monitoring of hydrogen gas, the display may incorporate an operator activation button 7. The controller may additionally or alternatively be pre-programmed to automatically monitor the hydrogen gas in the controlled atmosphere after a certain time interval or for a certain time period.

[39] To provide the required concentration of hydrogen gas and thereby help to maintain the desired controlled atmosphere in the atmosphere, the controller means may be a closed-loop controller configured to control the supply of hydrogen gas into the working chamber in accordance with the measured concentration of hydrogen gas. Hence, the concentration of hydrogen gas in the controlled atmosphere can be automatically and continuously controlled with minimal or no input from an operator.

[40] Microbiological processes conducted in the working chamber may generate byproducts that have a deleterious effect on the sensing performance of the hydrogen sensor. These include, for example, volatile fatty acids and/or hydrogen sulphide. Water vapour condensate may also degrade the hydrogen sensor if it is able to form on the sensor. In the embodiments depicted in Figures 1 to 4, the hydrogen gas sensor is located in an enclosure 8 to help shield the hydrogen sensor from one or more degrading products. The enclosure is a housing arranged in the return flow path of the circulating atmosphere and it comprises an inlet 9 and an outlet 10 to guide at least a portion of return flow atmosphere through the enclosure and across the hydrogen sensor.

[41] The enclosure may further comprise a filter to remove one or more degrading products carried by the atmosphere. The filter may be arranged at the inlet. As shown in Figures 3 and 4, the controller 5 may also be located in the enclosure 8 to shield it from degrading products.

[42] To further protect the hydrogen sensor 4 (and optionally the controller 5) from degrading products and avoid temperature fluctuations, the hydrogen sensor (and optionally the controller 5) may be located in a sensing portion 11 of the working chamber that is set apart from a processing portion 12 of the working chamber where the microbiological processes occur. In the particular embodiments shown, the working chamber is divided into the sensing portion and the processing portion using a floor partition 13, although other partition configurations may be suitable. The floor partition is configured to define a rear inlet 14 and a front outlet 15 in the sensing portion so as to guide at least a portion of the return flow atmosphere under the floor partition 13, through the sensing portion 11 and thereby through the enclosure 8.

[43] By shielding the hydrogen sensor 4 from degrading products the hydrogen sensor can safely remain in the workstation, even whilst the workstation is operational. The reliability and lifespan of the hydrogen sensor is improved. Hence, the hydrogen sensor in the present invention is not limited to sensing prior to microbiological work and it does not need to be manually removed from the workstation prior to operation.

[44] The chemical composition of the desired controlled atmosphere in the workstation may comprise multiple gases including nitrogen, carbon dioxide, oxygen and hydrogen. However, the presence of carbon dioxide gas and/or oxygen gas in the controlled atmosphere of the working chamber can compromise the sensing of the hydrogen sensor 4 and distort the gas data collected by the hydrogen sensor. It follows that the concentration of hydrogen gas determined from the distorted gas data is unreliable.

[45] To compensate for the distorting effect that the carbon dioxide gas and/or oxygen gas may have on the hydrogen sensor, the controller 5 may be configured to apply a distortion adjustment to the gas data of the hydrogen sensor 4 so as to correct the distortion errors. The distortion adjustment is dependent on the type of distorting gas present in the atmosphere, concentration of distorting gas and distorting effect. When the distortion errors have been removed from the gas data of the hydrogen sensor, the controller 5 can use the corrected gas data to more accurately determine the concentration of the hydrogen gas in the controlled atmosphere.

[46] In the embodiment depicted in Figure 3, the distortion adjustment data is predetermined based on expected distorting gases in the chamber atmosphere and preprogrammed into the controller 5. In the embodiment depicted in Figure 4, the workstation comprises a distorting gas analyser to provide real-time or near-time distortion analysis and control. The analyser comprises one or more distorting gas sensors including a carbon dioxide sensor 16 to detect for carbon dioxide gas and an oxygen sensor 17 to detect for oxygen gas in the atmosphere of the working chamber. The analyser also comprises a distorting gas controller 18 to process the gas data of the distorting gas sensors and determine a distortion adjustment representative of the distorting effect carbon dioxide and/or oxygen has on the hydrogen gas sensor. The distorting gas controller may be located within or external to the working chamber. The distortion gas controller sends the determined distortion adjustment to the controller 5 and the controller 5 corrects the gas data of the hydrogen sensor using the determined distortion adjustment.

[47] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. A system for monitoring an atmosphere in a chamber of a controlled atmosphere workstation, the system comprising:

2. A system according to claim 1, wherein the first gas sensor is a hydrogen sensor to detect for hydrogen gas in the atmosphere.

3. A system according to claim 1, wherein the protector comprises an enclosure configured to substantially shroud the first gas sensor from one or more degrading products.

4. A system according to claim 3, wherein the enclosure comprises an inlet and outlet to guide at least a portion of the atmosphere through the enclosure and across the first gas sensor.

5. A system according to claim 1, wherein the protector comprises a screen configured to partition the chamber of the workstation into:

a sensing region in which the first gas sensor is located; and a processing region in which work can be conducted.

6. A system according to claim 5, wherein the screen is a false floor panel.

7. A system according to claim 5 or 6, wherein the screen defines an inlet and outlet in the sensing region to guide at least a portion of the atmosphere through the sensing region and across the first gas sensor.

8. A system according to claim 4 or 7, wherein the at least a portion of the atmosphere is at least a portion of the return flow of the atmosphere.

9. A system according to any preceding claim wherein the controller is configured to compare the determined concentration of first gas with a required concentration of the first gas or required concentration range of the first gas to determine if the concentration of first gas in the atmosphere is sufficient or insufficient.

10. A system according to claim 9, wherein the controller is a closed-loop controller configured to control a supply of first gas to the chamber in accordance with the determined concentration of the first gas.

11. A system according to any preceding claim, wherein the controller is configured to correct distortion errors in the gas data of the first gas sensor.

12. A system according to claim 11, wherein the controller is configured to correct distortion errors in the gas data using a distortion adjustment based on one or more distorting gases in the atmosphere.

13. A system according to claim 12, wherein the distortion adjustment is a predetermined distortion adjustment received by the controller.

14. A system according to claim 12, wherein the distorting adjustment is a determined distortion adjustment received by the controller and the system further comprises a distorting gas analyser to detect for one or more distorting gases in the atmosphere and determine the distortion adjustment based on the one or more distorting gases data.

15. A system for monitoring an atmosphere in a chamber of a controlled atmosphere workstation, the system comprising:

a first gas sensor to detect for a first gas in the atmosphere; a protector to shield the first gas sensor from one or more degrading products; a closed-loop controller configured to correct distortion errors in the gas data of the gas sensor;

determine the concentration of the first gas in the atmosphere based on the corrected gas data of the first sensor; and control a supply of first gas to the chamber based on the determined concentration of the first gas and desired concentration of the first gas.

16. A controlled atmosphere workstation comprising:

a chamber with a controlled atmosphere;

a system for monitoring the atmosphere in the chamber according to any of claims 1 to 15

17. A method for monitoring the atmosphere in a chamber of a controlled atmosphere workstation, the method comprising:

sensing for a first gas in the atmosphere;

shielding the first gas sensor from one or more degrading products; processing the first gas data and determining the concentration of the first gas in the atmosphere based on the first gas data.

18. The method according to claim 17, further comprising guiding at least a portion of the atmosphere across the first gas sensor, preferably at least a portion of the return flow of the atmosphere.

19. The method according to claim 17 or 18, further comprising comparing the determined concentration of the first gas with a required concentration of the first gas or required concentration range of the first gas and determining if the determined concentration of the first gas is sufficient or insufficient.

20. The method according to claim 19, further comprising controlling a supply of first gas into the chamber in accordance with the determined concentration of the first gas.

21. The method according to any of claims 17 to 20, further comprising, prior to determining the concentration of the first gas in the atmosphere, correcting distortion errors in the first gas data due to one or more distorting gases in the atmosphere using a distortion adjustment.

22. The method according to claim 21, wherein the distortion adjustment is a predetermined distortion adjustment.

23. The method according to claim 21, wherein the distortion adjustment is a determined distortion adjustment and further comprising sensing for one or more distorting gases and determining the distortion adjustment based on the one or more distorting gases data.

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