Hydrogen supply method and system

Patent metadata

Field	Value
Publication number	US-9574715-B2
Application number	US-201414574945-A
Country	US
Kind code	B2
Filing date	Dec 18, 2014
Priority date	Feb 16, 2012
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

A method and system for supplying additional hydrogen from a reservoir of stored hydrogen in a salt cavern to a hydrogen pipeline to assist in meeting customer demand for hydrogen is provided. Contaminants introduced while the stored hydrogen stream is in the salt cavern may cause the crude hydrogen stream to not have the required product purity specification. The stored hydrogen is removed from the salt cavern as a crude hydrogen stream and thereafter diluted with higher purity hydrogen formed from the pipeline to form a hydrogen product stream at or below the product purity specification. The hydrogen product can be formed without removal of any of the contaminants in the crude stream, thereby creating a more cost effective and simplified supply process compared to conventional processes employing a salt cavern for hydrogen supply.

First claim

The invention claimed is:

1. A supply system for supplying additional hydrogen to a hydrogen pipeline from a salt cavern to assist in meeting customer demand for hydrogen, said supply system comprising:
an outlet flow network positioned between the pipeline and the salt cavern and having a first leg, a second leg, a third leg, a first control valve and a second control valve,
the first leg in flow communication with the salt cavern to discharge a crude hydrogen stream from the salt cavern, the crude hydrogen stream containing contaminants imparted by the salt cavern such that the crude hydrogen stream contains at least one of the contaminants at a level higher than that allowed by a product purity specification;
the second leg in flow communication with the pipeline and the first leg such that a hydrogen dilution stream, formed from the hydrogen contained in the pipeline, mixes with the crude hydrogen stream, the hydrogen dilution stream containing each of the contaminants at a concentration less than the product purity specification such that the hydrogen dilution stream dilutes the crude hydrogen stream and thereby forms a hydrogen product stream with lower levels of contaminants than the crude hydrogen stream;
the third leg in flow communication with the first leg, the second leg and the pipeline to introduce the hydrogen product stream into the pipeline and thereby to supply the additional hydrogen to the pipeline;
the first control valve located in the first leg to control a first flow rate of the crude hydrogen stream to a level that will assist in meeting the customer demand for the hydrogen and the second control valve located in the second leg to control flow of the hydrogen dilution stream at a second flow rate; and
a control system connected to the second control valve and configured to control valve opening of the second control valve and, therefore, the second flow rate such that the contaminants are present in the hydrogen product stream at or below the product purity specification.

2. The supply system of claim 1 , wherein the concentration of each of the contaminants within the hydrogen dilution stream is no greater than 80 percent of the product purity specification.

3. The supply system of claim 1 , wherein a compressor is positioned between the pipeline and the second leg to form the dilution hydrogen stream at a pressure above pipeline pressure of the hydrogen contained in the pipeline.

4. The supply system of claim 1 wherein a mixing vessel is connected to the first leg, the second leg and the third leg such that the hydrogen dilution stream mixes with the crude hydrogen stream within the mixing vessel and the product hydrogen stream is discharged from the mixing vessel.

5. The supply system of claim 1 , wherein:
the control system includes a supervisory level of control configured to calculate a calculated value of the second flow rate for the hydrogen dilution stream at which the contaminants will be present in the hydrogen product stream at or below the product purity specification and to generate a target flow signal referable to the calculated value; and
a flow controller responsive to the target flow signal and connected to the second control valve to control the second flow rate such that the second flow rate is about equal to the calculated value.

6. The supply system of claim 5 , wherein:
the control system has a first bank of concentration analyzers connected to a first sample line of the first leg and configured to sample concentration levels of the contaminants in the crude stream and to generate first measurement signals referable to concentration levels of contaminants in the crude hydrogen stream and a second bank of concentration analyzers connected to the second leg and configured to sample concentration levels of the contaminants in the hydrogen dilution stream and to generate second measurement signals referable to concentration levels of contaminants in the hydrogen dilution stream; and
the supervisory level of control is responsive to the first measurement signals and the second measurement signals and the first flow rate and is configured to determine the calculated value for the second flow rate and a calculated value of concentration levels of contaminants in the hydrogen product stream by performing material balances for each of the contaminants in the crude stream that exceeds the product purity specification such that the calculated level of the contaminants in the hydrogen product stream will be at or below the product purity specification.

7. The supply system of claim 6 , wherein the supervisory level of control is configured to perform integrity checks on the first and the second measurement signals to assess reliability of the first and the second measurement signals.

8. The supply system of claim 6 , wherein:
the first bank of concentration analyzers connected to a second sample line of the third leg is configured to sample concentration levels of the contaminants in the product stream to generate third measurement signals referable to concentration levels of contaminants in the hydrogen product stream;
the supervisory level of control is responsive to the third measurement signals and is configured to correct the measurement signals with a trailing bias value to generate a reconciled value that is utilized to compute a deviation of the reconciled value from the calculated value of the concentration levels of the contaminants in the hydrogen product stream to generate model errors; and
the supervisory level of control is configured to compare the model error for each of the contaminants in the hydrogen product stream to a corresponding predetermined acceptable limit and thereafter generate a flow signal to export the hydrogen product stream to the pipeline when each of the model errors for the contaminants is less than the corresponding predetermined acceptable limit.

9. A supply system for supplying additional hydrogen from a reservoir of stored hydrogen in a salt cavern supplied to an end-user through a hydrogen pipeline, the system comprising:
an outlet flow network operably connected to the salt cavern and having a first leg, a second leg, a third leg, a first control valve and a second control valve;
the first leg in flow communication with the salt cavern to discharge a crude hydrogen stream from the salt cavern, the crude hydrogen stream containing at least one contaminant imparted by the salt cavern such that the crude hydrogen stream contains at least one of the contaminants at a level higher than that of a product purity specification and requiring greater than about 95% hydrogen purity;
the second leg in flow communication with the first leg and comprising a hydrogen dilution stream formed from the hydrogen contained in the pipeline, the hydrogen dilution stream containing each of the at least one contaminants at a concentration less than the product purity specification;
the third leg in flow communication with the first leg and the second leg to form the hydrogen product stream;
the first control valve located in the first leg to control a first flow rate of the crude hydrogen stream and the second control valve located in the second leg to control flow of the hydrogen dilution stream at a second flow rate; and
a control system connected to the first control valve or the second control valve and configured to control the opening of the first control valve or the second control valve such that each of the at least one contaminants are present in the hydrogen product stream at or below the product purity specification.

10. The supply system of claim 9 , wherein the product purity specification for hydrogen ranges between about 97% and about 98

Assignees

• Oates Rommel M
• Dadebo Solomon
• Praxair Technology Inc

Inventors

• Oates Rommel M
• Dadebo Solomon

Classifications

• Y02E60/34

  Hydrogen distribution · CPC title

• Y10T137/87676

  With flow control · CPC title

• F17C2223/0123

  gaseous, e.g. CNG, GNC · CPC title

• F17D1/02

  for gases or vapours · CPC title

• F17C13/02

  Special adaptations of indicating, measuring, or monitoring equipment (measuring in general G01) · CPC title