In-Line Gas Purity Monitoring and Control System

• US 20090007777A1
• Filed: 09/19/2008
• Published: 01/08/2009
• Est. Priority Date: 02/04/2005
• Status: Active Grant

• Current Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Cohen, Joseph Perry, Farese, David John, Schweighardt, Frank Kenneth
• Granted Patent: US 7,793,675 B2
• Time in Patent Office: Days
• US Class Current: 95/8
• CPC Class Codes: B01F 23/191 characterised by the construction of the controlling means
• CPC Class Codes: B01F 35/213 of the properties of the mixtures, e.g. temperature, density or colour
• CPC Class Codes: G05D 11/138 by sensing the concentration of the mixture, e.g. measuring pH value
• CPC Class Codes: Y02E 60/36 Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
• CPC Class Codes: Y10T 137/0329 Mixing of plural fluids of diverse characteristics or conditions
• CPC Class Codes: Y10T 137/2499 Mixture condition maintaining or sensing
• CPC Class Codes: Y10T 137/2509 By optical or chemical property

Abstract

Method for supplying a high purity gas product comprising providing a first gas stream including a major component and at least one impurity component, determining the concentration of the at least one impurity component, and comparing the concentration so determined with a reference concentration for that component. When the value of the concentration so determined is less than or equal to the reference concentration, the first gas stream is utilized to provide the high purity gas product. When the value of the concentration so determined is greater than the reference concentration, a second gas stream comprising the major component is provided and the first and second gas streams are mixed to yield a mixed gas stream having a concentration of the at least one impurity component that is less than the reference concentration. The second gas stream is provided by dividing the first gas stream into a first substream and a second substream, removing at least a portion of the at least one impurity component in the first substream to provide a purified substream, and mixing the purified substream with the second substream to provide the high purity gas product. The mixed gas stream is utilized to provide the high purity gas product.

Claims

1. A method for supplying a high purity gas product comprising

(a) providing a first gas stream comprising a major component and at least one impurity component;

(b) determining the concentration of the at least one impurity component and comparing the concentration so determined with a reference concentration for that component;

(c) when the value of the concentration so determined is less than or equal to the reference concentration, utilizing the first gas stream to provide the high purity gas product; and

(d) when the value of the concentration so determined is greater than the reference concentration,

(1) providing a second gas stream comprising the major component, wherein the second gas stream is provided by dividing the first gas stream into a first substream and a second substream, removing at least a portion of the at least one impurity component in the first substream to provide a purified substream, and mixing the purified substream with the second substream to provide the high purity gas product; and

(2) mixing the first gas stream with the second gas stream to yield a mixed gas stream having a concentration of the at least one impurity component that is less than the reference concentration, and utilizing the mixed gas stream to provide the high purity gas product.

2. The method of claim 1 wherein the major component of the first gas stream is hydrogen.

3. The method of claim 2 wherein the at least one impurity component is selected from the group consisting of hydrogen sulfide;

carbonyl sulfide;

carbon monoxide;

hydrocarbons having up to 5 carbon atoms; and

compounds containing carbon atoms, hydrogen atoms, and one or more atoms selected from the group consisting of oxygen, nitrogen, and sulfur.

4. The method of claim 2 wherein the first gas stream is generated from a feed gas comprising one or more hydrocarbons having up to 5 carbon atoms by any of steam reforming, partial oxidation, and autothermal reforming.

5. The method of claim 2 wherein the hydrogen is generated by the electrolysis of water.

6. The method of claim 1 wherein the second gas stream is provided from a storage system that stores the gas as a compressed gas, a cryogenic liquid, an adsorbed gas, or a chemically bound gas.

7. The method of claim 6 wherein the major component of the first gas stream is hydrogen and the major component of the second gas stream is hydrogen.

8. The method of claim 7 wherein the storage system stores the gas as liquid hydrogen and the hydrogen in the second gas stream is provided by vaporizing the liquid hydrogen.

9. The method of claim 1 wherein the major component in the first and second gas streams is hydrogen and either (1) the first gas stream is provided by the electrolysis of water or the second gas stream is provided by the electrolysis of water or (2) the first gas stream is provided by the electrolysis of water and the second gas stream is provided by the electrolysis of water.

10. The method of claim 1 wherein the major component of the first gas substream is hydrogen and the major component of the second gas substream is hydrogen.

11. The method of claim 10 wherein at least a portion of the at least one impurity component in the first gas substream is removed therefrom by any method selected from the group consisting of permeation through a hydrogen-permeable membrane, pressure swing adsorption, thermal swing adsorption, and chemical reaction with a porous solid.

12. The method of claim 10 wherein the first gas stream is generated from a feed gas comprising one or more hydrocarbons having up to five carbon atoms by any of steam reforming, partial oxidation, and autothermal reforming.

13. The method of claim 10 wherein the hydrogen in the first gas stream is generated by the electrolysis of water.

14. The method of claim 1 wherein the concentration of the at least one impurity component in the first gas stream is determined by a sensor selected from the group consisting of field effect transistor (FET) sensors, microcantilever sensors, quartz-crystal sensors, electrolytic sensors, and chemiresistor sensors.

15. The method of claim 1 wherein the high purity gas product comprises hydrogen as the major component and wherein the high purity gas product is utilized as feed to a fuel cell.

16. An apparatus for generating a high purity gas product comprising

(a) a first flow control valve and piping means adapted to provide a first gas stream comprising a major component and at least one impurity component;

(b) a second control valve and piping means adapted to provide a second gas stream comprising the major component;

(c) a mixing zone having a first inlet, a second inlet, and an outlet, wherein the first inlet is in gas flow communication with the first flow control valve and piping means and the second inlet is in gas flow communication with the second control valve and piping means, and wherein the mixing zone is adapted to mix the first and second gas streams and provide a mixed gas stream via the outlet;

(d) an analysis zone having an inlet, an outlet, and at least one sensor adapted to measure the concentration of the at least one impurity component in the mixed gas stream and generate a first signal proportional to the concentration of the impurity component therein, wherein the inlet of the analysis zone is in gas flow communication with the outlet of the mixing zone and the outlet is adapted to provide the high purity gas product;

(e) control means adapted to receive the first signal, compare the first signal with a first parameter proportional to the concentration of the at least one impurity in the first gas stream and a second parameter proportional to a maximum allowable concentration of the at least one impurity in the high purity gas product, generate a second signal and a third signal, and transmit the second and third signals to the first and second flow control valves, respectively, such that the flow rates of the first and second gas streams can be adjusted to yield a concentration of the at least one impurity in the high purity gas product equal to or less than the maximum allowable concentration; and

(f) purifier means adapted for the removal of the at least one impurity from the first gas mixture, wherein the purifier means has an inlet and an outlet, piping means adapted to transfer a portion of the first gas mixture to the inlet of the purifier means, and piping means adapted to transfer a purified gas mixture from the outlet of the purifier to the second control valve.

17. The apparatus of claim 16 wherein the first gas stream comprises a plurality of impurity components and the analysis zone comprises a plurality of sensors, wherein each sensor is adapted to determine the concentration of a different impurity component.

18. The apparatus of claim 16 which further comprises means for generating the first gas mixture from a feed gas comprising one or more hydrocarbons having up to 5 carbon atoms by any of steam reforming, partial oxidation, and autothermal reforming.

19. The apparatus of claim 16 which further comprises either (1) means to provide the first gas stream by the electrolysis of water or means to provide the second gas stream by the electrolysis of water or (2) means to provide the first gas stream by the electrolysis of water and means to provide the second gas stream by the electrolysis of water.

20. The apparatus of claim 16 wherein the purifier means comprises a system selected from the group consisting of permeation through a hydrogen-permeable membrane, pressure swing adsorption, thermal swing adsorption, and chemical reaction with a porous solid.

21. A method for generating a high purity gas product comprising

(a) providing an apparatus comprising

(1) a first flow control valve and piping means and adapted to provide a first gas stream comprising a major component and at least one impurity component;

(2) a second control valve and piping means adapted to provide a second gas stream comprising the major component;

(3) a mixing zone having a first inlet, a second inlet, and an outlet, wherein the first inlet is in gas flow communication with the first flow control valve and piping means and the second inlet is in gas flow communication with the second control valve and piping means, and wherein the mixing zone is adapted to mix the first and second gas streams and provide a mixed gas stream via the outlet;

(4) an analysis zone having an inlet, an outlet, and at least one sensor adapted to measure the concentration of the at least one impurity component in the mixed gas stream and generate a first signal proportional to the concentration of the impurity component therein, wherein the inlet of the analysis zone is in gas flow communication with the outlet of the mixing zone and the outlet is adapted to provide the high purity gas product; and

(5) control means adapted to receive the first signal, compare the first signal with a first parameter proportional to the concentration of the at least one impurity in the first gas stream and a second parameter proportional to a maximum allowable concentration of the at least one impurity in the high purity gas product, generate a second signal and a third signal, and transmit the second and third signals to the first and second flow control valves, respectively, wherein

the first gas stream comprises a plurality of impurity components and the analysis zone comprises a plurality of sensors, and wherein each sensor is adapted to determine the concentration of a different impurity component;

(b) providing the first gas stream comprising the major component and the at least one impurity component;

(c) determining the concentration of the at least one impurity component, in the mixed gas stream, generating the first signal proportional to the concentration of the impurity component therein, and comparing the first signal so generated with the first and second parameters;

(d) when the value of the first signal so determined is less than or equal to second parameter, generating the second and third signals which open the first control valve and close the second control valve, respectively, such that the first gas stream provides the high purity gas product;

(e) when the value of the first signal so determined is greater than the second parameter,

(1) generating the second and third signals,

(2) providing the second gas stream comprising the major component,

(3) utilizing the second and third signals to control the first and second flow control valves, respectively, such that the signal proportional to the concentration of the at least one impurity component in the mixed gas stream is less than the second parameter, and

(4) utilizing the mixed gas stream to provide the high purity gas product;

(f) providing purifier means adapted for the removal of the at least one impurity from the first gas mixture, wherein the purifier means has an inlet and an outlet, piping means adapted to transfer a portion of the first gas mixture to the inlet of the purifier means, and piping means adapted to transfer a purified gas mixture from the outlet of the purifier to the second control valve; and

(g) removing at least a portion of the at least one impurity from the first gas mixture to provide the purified gas mixture and transferring the first gas mixture to the second control valve, wherein the purifier means comprises a system selected from the group consisting of permeation through a hydrogen-permeable membrane, pressure swing adsorption, thermal swing adsorption, and chemical reaction with a porous solid.

22. The method of claim 21 which further comprises generating the first gas mixture from a feed gas comprising one or more hydrocarbons having up to 5 carbon atoms by any of steam reforming, partial oxidation, and autothermal reforming.

23. The method of claim 21 wherein the first gas stream comprises hydrogen generated by the electrolysis of water.

24. An apparatus for generating a high purity gas product comprising

(a) a proportional flow control and mixing valve having a first inlet adapted to accept a first gas stream comprising a major component and at least one impurity component, a second inlet adapted to accept a second gas stream comprising the major component, and an outlet adapted to supply a mixed gas stream;

(b) an analysis zone having an inlet, an outlet, and at least one sensor adapted to measure the concentration of the at least one impurity component in the mixed gas stream and generate a first signal proportional to the concentration of the impurity component therein, wherein the inlet of the analysis zone is in gas flow communication with outlet of the proportional flow control and mixing valve and is adapted to provide the high purity gas product; and

(c) control means adapted to receive the first signal, compare the first signal with a first parameter proportional to the concentration of the at least one impurity in the first gas stream and a second parameter proportional to a maximum allowable concentration of the at least one impurity in the high purity gas product, generate a second signal proportional to the ratio of the first and second parameters, and transmit the second signal to the proportional flow control and mixing valve such that the flow rates of the first and second gas streams can be adjusted to yield a concentration of the at least one impurity in the high purity gas product equal to or less than the maximum allowable concentration.

25. The apparatus of claim 24 wherein the first gas stream comprises a plurality of impurity components and the analysis zone comprises a plurality of sensors, wherein each sensor is adapted to determine the concentration of a different impurity component.

26. The apparatus of claim 24 which further comprises means for generating the first gas mixture from a feed gas comprising one or more hydrocarbons having up to five carbon atoms by any of steam reforming, partial oxidation, and autothermal reforming.

27. The apparatus of claim 24 which further comprises either (1) means to provide the first gas stream by the electrolysis of water or means to provide the second gas stream by the electrolysis of water or (2) means to provide the first gas stream by the electrolysis of water and means to provide the second gas stream by the electrolysis of water.

28. The apparatus of claim 24 which further comprises purifier means adapted for the removal of the at least one impurity from the first gas mixture, wherein the purifier means has an inlet and an outlet, piping means adapted to transfer a portion of the first gas mixture to the inlet of the purifier means, and piping means adapted to transfer a purified gas mixture from the outlet of the purifier to second inlet of the proportional flow control and mixing valve.

29. The apparatus of claim 34 wherein the purifier means comprises a system selected from the group consisting of permeation through a hydrogen-permeable membrane, pressure swing adsorption, thermal swing adsorption, and chemical reaction with a porous solid.