Description:“UNINTERRUPTED FEED WATER SUPPLY SUBSYSTEM FOR CONTINUOUS OPERATION OF ELECTROLYSER”

FIELD OF INVENTION:
[001] The present invention generally relates to balancing of feed water supplied to an electrolyzer in case of any short fall in main feed water supply line for any kind of the electrolyzer type such as proton exchange membrane (PEM), Alkaline and Anion Exchange Membrane (AEM) which converts water to Hydrogen and Oxygen by means of electrochemical reaction in presence of DC power is being supplied. Precisely, the present invention relates to uninterrupted feed water supply for a given duration at rated pressure as required by the electrolyzer system feed water pressure line for trouble free operation in case of any sudden short fall in main feed water supply.

BACKGROUND / PRIOR-ART OF THE INVENTION:
[002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[003] Electrolysis is a process by which electric current (DC) passes through a substance to effect a chemical change. The chemical change is one in which the substance loses (reduction) or gains (oxidation) an electron. In case of water electrolysis, a polymer electrolyte membrane (PEM) electrolyzer, the electrolyte is a solid specialty material.

• Water reacts in the process oxidation at the anode to form oxygen and positively charged hydrogen ions (protons- H+).
• The electrons flow through an external circuit and the hydrogen ions selectively move across the PEM to the cathode.
• At the cathode, in the process of reduction, hydrogen ions combine with electrons from the external circuit to form hydrogen gas.

Anode Reaction (Oxidation): 2 H2O ? O2 + 4H+ + 4e-
Cathode Reaction (Reduction): 4H+ + 4e- ? 2H2

[004] To obtain hydrogen and oxygen by the process electrolysis, supply of DC power and water are the main key requirements. As the electrolysis requires very pure water, to obtain such quality of water all ions have to be removed (i.e. Deionized water) to meet the requirements of electrolyzer grade to protect the life of electrolyzer. The present invention relates to supply of feed water to overcome the shortfall in main water supply line using a small water reservoir to enable water supply in parallel to main water supply line.

[005] Reference may be made to Patent No 368027, Dated 31.05.2021 and titled METHOD OF UNINTERRUPTED OPERATION OF HIGH-PRESSURE WATER ELECTROLYSIS SYSTEM". This explains about apparatus used in electrolyser for continuous operation and makes sure that hydrogen and oxygen are produced without intervention of additional pump and controller setup. The apparatus finds use in portable oxygen and hydrogen generators. The apparatus enables autonomous operation of solar-electrolyser-fuel cell hybrid power system, under consideration for remote locations. This relates in general to PEM Water electrolysis, and in particular a novel simplified operation logic for high pressure installation using PEM electrolyser for Hydrogen and Oxygen gas generation and method for operating such installation for continuous production of Hydrogen and Oxygen gases, specifically under autonomous conditions. Water is supplied to anode and cathode current collectors. On the anode side of the membrane electrode assembly, water is decomposed to generate protons and these protons along with water molecules, are conducted to cathode through proton conducting solid membrane and combine with electrons to form hydrogen at cathode. Simultaneously oxygen is generated at the anode side of the cell. Water circulation is maintained in excess to ensure (i) constant supply of water at anode for reactions (ii) effective removal of gases generated on both anode and cathode. Water is transported to cathode side of the stack along with protons due to electro osmatic drag and consumption of water on anode side is much more than what is required just to generate Hydrogen and Oxygen alone.

[006] The aforesaid prior art can’t full fill the requirements of the invention for which it has been designed. Hence, the present invention has been proposed.

OBJECTS OF INVENTION:

[007] Primary object of the invention is to provide Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser, which is simple in construction.

[008] An object of the invention is to provide Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser, wherein modular subsystem is developed whose capacity for water and gas holding can be defined based on the backup duration requirement given and compatible to assemble in line with the feed water supply line.

[009] Another object of the invention is to ensure gas pressure of defined value that is to be supplied by any means through a source of Nitrogen cylinder/air compressor to exert pressure over the water storage tank placed in parallel to main feed water supply line.

[0010] Still another object of the invention is to develop a semi-auto mechanism to ensure that the water from main feed stream is being supplied to standby water tank with no reverse flow of water from standby tank to main water feed tank.

[0011] Yet another object of the invention is to develop a process that gas is not allowed to flow into the electrolyser feed water supply side in case the water available in the standby water tank is about to complete.

[0012] One another object of the invention is to develop a mechanism to operate the electrolyzer for continuous operation using an external water supply in case of any breakdown in the main feed water supply line using any external water supply source.

[0013] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.

SUMMARY OF THE INVENTION:

[0014] One or more drawbacks of conventional systems and process are overcome, and additional advantages are provided through the apparatus/composition and a method as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be part of the claimed disclosure.

[0015] The apparatus includes controller which receives the height measurement of water reservoir using differential pressure transmitter (DPT) sensor connected across the water reservoir tank. The sensor communicates the information of water level in the reservoir, wherein on receipt of signal from the DPT sensor, the controller processes information and responds to supply the power (DC/ AC) in terms of ON/ OFF commands to power the solenoid valve placed between water reservoir and pneumatic line.
[0016] One side of the apparatus can be connected to any size of water reservoir of any shape and capacity and the other side can be connected to pneumatic supply source line which could be from any gas storage tank or air compressor connected with a pressure regulator to supply the gas at constant pressure to be applied on the water storage tank to push the water to feed at the DI water generator feed supply port with desired pressure.

[0017] The apparatus of the invention can be used as an online UPS, in place of power it would provide water supply for required period of time such as minutes to one hour. Beyond which, the reservoir has provision to connect external pipeline using which the DI water required for electrolyzer operation can be supplied by enabling continuous supply of raw water at the feed port of DI water generator.

[0018] The water reservoir of invention is provided with manual valve to depressurize the gas occupied by the gas to pressurize the water reservoir, in which the same gas is depressurized using a manual valve provided at the top side of the reservoir and to ensure auto refilling of water reservoir whenever the main water supply line is enabled. Also the controller of the apparatus senses the water level raised in the reservoir, which sends the signal for maximum water level (Lm) and power supply would be enabled to the solenoid valve (normally closed when no power) to ensure pressure is exerted by the pneumatic supply from the gas supply line to balance the pressure and the system gets stabilized.

[0019] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

[0020] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.

[0021] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING:

[0022] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and processes that are consistent with the subject matter as claimed herein, wherein:
[0023] Figure 1 shows: Schematic of Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser, wherein apparatus is connected in parallel to main water supply line according to the present invention.
[0024] The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWING:

[0025] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

[0026] The present invention relates to a technology pertinent to invention directing to Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser.

[0027] According to the invention, the electrolysis apparatus includes water electrolyser stack, which generates hydrogen and oxygen gases on continuous supply of DC power and water. Separate pumps are employed to circulate water through water electrolyzer stack from Deionized (DI) water storage tank. The DI water is being generated using DI water system which comprises of series water filters for removal any dirt, chlorine and fine particulate matter. In addition to these filters, there are reverse osmosis filters to further purify the water followed Ion exchange unit from which desired water quality of resistivity >5Mohms can be achieved. Finally, the same water would be used for recirculation through the electrolyzer cell for production of Hydrogen and Oxygen. To obtain such water quality from DI water, the feed water has to undergo for multiple stages of purification, in order to process the purification steps involved in the feed water requires minimum of 2 bar pressure to over all the steps involved at multiple stages. To overcome this pressure drop, feed water from overhead tanks or by means of pumps would be supplied to water purification inlet.
[0028] Typical operating pressure of the electrolyzer Hydrogen is 10-40 bar, oxygen is produced at ambient pressure. In case of any emergency like hydrogen leaks in the electrolyser, DI water supply shortage or power supply failure, the system would be provided with all safety functions in place, in such case hydrogen vent would be opened to depressurize the system and inert gas like Nitrogen would be circulated throughout the Hydrogen lines. One such case is being addressed here is mitigation of feed water supply interruption.

[0029] A novel approach has been attempted successfully to minimize the risk of feed water supply discontinuity and to minimize number of shutdowns by providing parallel water supply for DI water generator system without disturbing the main feed water line as shown in Fig 1.

[0030] All the subsystems required for normal operation of electrolyser system (1) has been considered as single unit which is in communication with DC power supply (2) to supply the rated DC power to power the electrolyser system (1) for production of Hydrogen and Oxygen at cathode (-Ve) and anode (+Ve) respectively as per the reactions described below for continuous supply of water by DI water pump (3).
Anode:
H2O --------------?^ 2H+ + 1/2 O2 + 2e-
Cathode:
2H++2e----------?^ H2

[0031] The DI water required for the electrochemical reaction is sourced from the DI water storage tank (4) which is the source of DI water storage reservoir, one side of which is in fluid communication with the DI water pump (3) inlet and the other side is in communication with the DI water generator (5) outlet. The DI water generator (5) produces very high purity water from the raw water received at the DI generator feed water source (6). Upon multiple stages of operations DI water generator (5) produces high pure water as required by the Electrolyser grade water (resistivity >5 Mohms) requirements.

[0032] Typically, the raw water (6) is sourced either from any primary sources of overhead tanks/ rivers/ ground water or from water pipe line having supplied pressure of higher than 2 bar by any means of pressure boosting if the supplied pressure is lower than 2 bar rating failing which the DI water generator cannot process feed water (6) to obtain electrolyzer grade water quality. The feed water should be free from particulate matter, all particulate matter has been removed by particulate filter (7) placed between check valve (8) and main raw water supply (primary) source (9) to avoid any contamination and choking in the downstream pipe lines. There is a T- connection (10) made available in order to provide an additional water supply (secondary) line (11) to ensure that the water is supplied uninterruptedly in case of any short fall from the main supply water source (9) without feeding the water back to main source line, which is possible by placing the check valve (8) which does not allow back flow into line of main feed water supply line (9).
[0033] In case of any short fall of main water supply (9), the secondary water supply (11) is enabled automatically at T-junction (10) which is in fluid communication with primary water line (9) and secondary water line (11) while the water supply for the DI generator (5) is continuously sourced from primary water supply line (9). On short fall of primary water supply (9), secondary water (11) from storage tank (12) becomes active as the primary supply water pressure decreases continuously, water from storage tank (12) is supplied continuously to meet the required flow of feed water (6) with the preset pressure of 2 bar or above adjusted by the pressure regulator (12) connected to any gaseous storage source tank (13) or air compressor and whose pressure has been regulated using pressure regulator (14). The water level in the water storage tank (12) continuously decreases and the same can be monitored using a differential pressure transmitter (15) placed across the water storage tank which supplies either 4-20 mA current signal or 0-5 VDC to controller (16) which is in communication with the solenoid valve (17) placed after pressure regulator (14). Typically, the solenoid valve (17) with integrated check valve can be powered with AC or DC power source supplied from controller box (16) either to close or open the valve. Once, the primary water supply is interrupted, water is supplied from secondary storage tank (12) until the water level reaches to the minimum (L0) possible level further which the gas is expected to enter into the DI water generator (5) could lead to malfunction of the system. To overcome such gas entrainment into the DI water generator (5), source of pressure is cut-off by closing the gas supply from the cylinder using a solenoid valve (17) which gets activated by the power supply ON command received from the controller (16) to the solenoid valve (17). Controller (16) is typically used to communicate ON/OFF power supply commands in response to the water level in the reservoir tank (12). In addition to this, there has been a provision made to a manual valve to release the gas filled in the storage tank to provide space for refilling of water from the primary water line is enabled. Once the water level in the reservoir tank (12) reaches to level L1, the height of the water is sensed by the differential pressure transmitter (15) with higher value of signal than the value of level L0, which would enable the controller (16) to cut-off the power supply signal to the solenoid valve (17), therefore the gas supply could be enabled and induce the pressure balance in the storage. Typical set pressure adjusted by pressure regulator is lower than the pressure of the primary water line pressure. An addition drain valve (19) has been provided at the bottom of the tank for tanks cleaning or to enable any external supply of water to run the electrolyze continuously connecting external line to the adaptor (20) of equivalent pipe size.

Advantages of Invention
- Simple in construction;
- User friendly;
- Water from main feed stream is supplied to standby water tank with no reverse flow of water from standby tank to main water feed tank;
- Gas is not allowed to flow into the electrolyser feed water supply side in case the water available in the standby water tank is about to complete;
- Functions efficiently.

Working of Invention
[0034] For uninterrupted function of Millipore system in Electrolyser it requires minimum of 2 Bar water pressure. When the main supply tank gets empty the pressure falls below the requirement and the Millipore system turns off. For overcoming this issue along with the supply of feed water to the Millipore in the electrolyzer system an external pressurized tank holding a pressure of 2-4 Bar has been connected in parallel. The feed water from the main supply tank also holds at 2-4 Bar. When the main supply tank pressure is maintained the external pressure tank will not be contributing. As soon as the main supply tank pressure falls below 2 bar the external tank will feed the required pressure with water supply and maintain the system running. Depending on the volume of the external cylinder the backup time will be occurred. For the current design 60 mins backup has been achieved.
Test Result

[0035] After Design, Fabrication and Installation of the external pressure tank parallel to the feed water it was tested for leaks and integrated. After integration the system was tested in various scenarios as given below in the table.
Sl.No Feed Water Pressure (BAR) External Tank Pressure (BAR) Millipore System Status
1 4 0 ON
2 3 0 ON
3 2 0 ON
4 1 0 OFF
5 0 0 OFF
6 4 3 ON
7 3 3 ON
8 2 3 ON
9 1 3 ON
10 0 3 ON

[0036] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0037] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.

[0038] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particulars claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogues to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B”.

[0039] The above description does not provide specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.

[0040] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.

[0041] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.

[0042] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
, Claims:WE CLAIM:

1. Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser comprises of electrolyser system (1) which is in communication with DC power supply (2) to supply the rated DC power to power the electrolyser system (1) for production of Hydrogen and Oxygen at cathode (-Ve) and anode (+Ve) respectively for continuous supply of water by DI water pump (3), wherein the DI water required for the electrochemical reaction is sourced from the DI water storage tank (4), one side of which is in fluid communication with the DI water pump (3) inlet and the other side is in communication with the DI water generator (5) outlet; a T- connection (10) is provided for an additional water supply (secondary) line (11) to ensure that the water is supplied uninterruptedly in case of any short fall from the main supply water source (9).

2. The Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser as claimed in claim 1, wherein the DI water generator (5) produces pure water from raw water received at the DI generator feed water source (6), in which upon multiple stages of operations DI water generator (5) produces high pure water as required by the Electrolyser grade water (resistivity >5 Mohms) requirements.

3. The Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser as claimed in claim 1 or 2, wherein the raw water (6) is sourced either from primary sources of overhead tanks/ rivers/ ground water, alternatively from water pipe line having supplied pressure of higher than 2 bar by pressure boosting if the supplied pressure is lower than 2 bar rating failing which the DI water generator cannot process feed water (6) to obtain electrolyzer grade water quality.

4. The Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser as claimed in claims 1-3, wherein the particulate matter is removed by particulate filter (7) placed between check valve (8) and main raw water supply (primary) source (9) to avoid contamination and choking in the downstream pipe lines, in which the check valve (8) avoids back flow into line of main feed water supply line (9).

5. The Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser as claimed in claims 1-4, wherein in case of any short fall of main water supply (9), the secondary water supply (11) is enabled automatically at T-junction (10) which is in fluid communication with primary water line (9) and secondary water line (11) while the water supply for the DI generator (5) is continuously sourced from primary water supply line (9).

6. The Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser as claimed in claims 1-5, wherein on short fall of primary water supply (9), secondary water (11) from storage tank (12) becomes active as the primary supply water pressure decreases continuously, in which water from storage tank (12) is supplied continuously to meet the required flow of feed water (6) with the preset pressure of 2 bar/above adjusted by the pressure regulator (12) connected to gaseous storage source tank (13)/ air compressor and whose pressure is regulated using pressure regulator (14).

7. The Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser as claimed in claims 1-6, wherein the water level in the water storage tank (12) continuously decreases, which is monitored using a differential pressure transmitter (15) placed across the water storage tank which supplies either 4-20 mA current signal/ 0-5 VDC to controller (16) which is in communication with the solenoid valve (17) placed after pressure regulator (14).

8. The Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser as claimed in claims 1-7, wherein Once, the primary water supply is interrupted, water is supplied from secondary storage tank (12) until the water level reaches to the minimum (L0) possible level, in which source of pressure is cut-off by closing the gas supply from the cylinder using a solenoid valve (17) which gets activated by the power supply ON command received from the controller (16) to the solenoid valve (17).

9. The Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser as claimed in claims 1-8, wherein the controller (16) is provided to communicate ON/OFF power supply commands in response to the water level in the reservoir tank (12), in which a manual valve is provided so as to release the gas filled in the storage tank to provide space for refilling of water from the primary water line.

10. The Uninterrupted Feed water supply subsystem for continuous operation of Electrolyser as claimed in claims 1-9, wherein once the water level in the reservoir tank (12) reaches to level L1, the height of the water is sensed by the differential pressure transmitter (15) with higher value of signal than the value of level L0, which enables the controller (16) to cut-off the power supply signal to the solenoid valve (17), therefore the gas supply is enabled and induces the pressure balance in the storage, in which a drain valve (19) is provided at the bottom of the tank for tanks cleaning / to enable external supply of water to run the electrolyze continuously connecting external line to the adaptor (20).