Title of Invention

SOLID STATE ELECTROCHEMICAL HYDROGEN SENSOR

Abstract

The present invention relates to state electrochemical hydrogen sensor coprising of soild ion electrolyte, solid reference electrode and working electrode. The hydrogen sensor of the present of the present invention has stable and reversible solid reference electrode; using solid-state electrochemical cell technology for the quantitive measurement of wide variation of composition. The present invention is an improved solid-state electrochemical hydrogen sensor by method of contacting the solid reference electrode with solid electrolyte and used for detection of hydrogen.

Full Text

FORM 2 THE PATENT ACT 1970 & The Patents Rules, 2003 PROVISIONAL / COMPLETE SPECIFICATION (See section 10 and rule 13) 1. TITLE OF THE INVENTION SOLID STATE ELECTROCHEMICAL HYDROGEN SENSOR 2. APPLICANT (a) NAME: CATALYSTS HY SENSING TECHNOLOGIES PVT. LTD. (b) NATIONALITY: Indian Company, registered under the provisions of the Companies Act, 1956 (c) ADDRESS: D 2/6 Liberty II, Morth main Road, Koregaon Park, Pune-411001 3. PREAMBLE TO THE DESCRIPTION PROVISIONAL The following: invention,. describes the COMPLETE The following specification particularly describes the invention and the manner in which it is to be performed. 4. DESCRIPTION (Description starts from page 2) 5. CLAIMS: Given on a separate sheet. 6. DATE AND SIGNATURE: Given at the end of last page of specification. 7. ABSTRACT OF THE INVENTION: Given on a separate sheet. 1 Technical Field: The present invention relates to a solid state electrochemical hydrogen sensor. More particularly, the present invention relates to proton conducting solid electrolyte and a novel solid reference electrode used for detection of hydrogen. Background and Prior Art: Hydrogen has excellent thermal conductivity {4.9units as compared to 1 unit for oxygen and} hence finds use as a coolant in application where rapid heat dissipation is of prime importance e.g. in Turbo Power Generators. However at the same time it is vastly explosive (Range 4% to 76% in air). It is highly leaky, being the lightest molecule, leading to constant pressure on the operators to maintain their machines leak proof. Turbine designers and manufactures, in there operational manuals have recommended several locations of the generator to be routinely checked for leakages. It would be most appropriate to employ on-line monitoring. The fluid in power transformers acts as a dielectric media, an insulator and as a heat transfer agent. Mineral oils are the most commonly used media, although silicones can also be used. During normal use, the mineral oil continues to degrade which produces certain gases including hydrogen. Oil can react with oxygen and moisture and other atmospheric contaminates, causing degradation. Any heating also produces decay products in oil .If there is an electrical fault, gases are produced at a higher rate .The faults with increasing severity are partial discharge, local hot spots and arcing. These can cause explosions & outage. Hydrogen is produced to a greater or lesser extent by all types of fault. Hydrogen has a low solubility in oil but a high diffusivity. If gas space is available Hydrogen will accumulate in the gas space even without fault but due to low level of degradation. Hydrogen is seen as a very important fault gas and the "health" of the transformer strongly correlates with the concentration of hydrogen in oil. The value of on-line 2 monitoring of Hydrogen for both life extension & transformer protection purposes is now well established. Though ideally one would like to install such a monitor within the oil to monitor the dissolved Hydrogen in oil, simplicity and cost effectiveness could be a major impediment for such an application. Our suggested type of SENSOR can be installed, static in gas space for achieving the same objective, at a highly affordable cost and with simplicity. The Hydrogen concentration in the oil can vary from 20 to 4000ppm (this is volume concentration in oil) with the oil temperature varying from room temperature to 100° C .The corresponding Hydrogen concentration in the gas phase as measured by the sensor essentially gives the partial pressure of Hydrogen. E.g. A partial pressure of 0.00latm at total gas pressure of latm corresponds to gaseous volume concentration of l000ppm.OR 0.1%. This implies that 99.9% volume of the gas contains other components such as nitrogen, moisture, if any oxygen and other hydrocarbon vapour. Thus the ppm concentration in the gas phase is a different unit from the ppm concentration in oil. 1000ppm Hydrogen in oil phase implies that the oil phase contains 99.9% of other components, most of which is oil. Thus a correlation will be required connecting hydrogen ppm in oil to hydrogen ppm in gas. For example, if the background hydrogen in oil is lOppm. But the hydrogen in gas is 150ppm.assuming a linear co-relation, the scale down factor from gas to oil is 15. There is equilibrium between gas and oil. If there is leak, under normal condition hydrogen is leaving the oil via the gas phase to the environment. Hydrogen has higher diffusivity than any other dissolved gases in oil, hence will tend to accumulate in the gas phase more readily. Any local heating or a transient arcing will result in a rapid rise in hydrogen in the gas phase, indicating the occurrence of these events. These can be self-correcting with hydrogen leaking out of the oil in time. But any sustained fault will result in high levels of hydrogen. Sudden increase in hydrogen generating range will point to incipient failure of transformer. 3 Most existing techniques are based on co-relation method, whereas the subject sensors measures hydrogen directly and specifically over a wide range of concentration. The other many varieties of commercial sensors available are: 1. Catalytic Bead Gas detectors: The response of these sensors is determined by surface chemistry and device structure. In its present form the technology is mature and significant further development is unlikely. These sensors have severe difficulties of reproducibility and selectivity, and the technology has not generally been perceived to be sufficiently reliable for most industrial application. Poor poison resistance and relatively high operating temperature militate against significant expansion of market for these sensors. Poor pay back as they are expensive; cost over $2000 is typical. 2. Semi-conductor detectors: These are largely based on gas-sensitive conductivity responses upon Sn02 or ZnO. Devices based on these, though, in their widest interpretation, offered the broadest road forward in terms of new materials, miniaturization and silicon-compatible technology, suffer from being inherently nonselective and strongly affected by atmospheric contaminants. It is very demanding in terms of close control over many parameters, such as, temperature of operation, device porosity, device particle size, doping materials, catalyst materials, coating materials and temperature cycling, for achieving selectivity and durability. Semi-conductor sensor technology has reached maturity in respect of the empirical development of Sn02 and similar materials. Though cheaper than Catalytic Sensor, suffers irreversibly in high hydrogen environment. 3. Electrochemical Sensors: These require replenishment of electrolyte, suffers from cross-sensitivity, effective in low hydrogen environment, higher response time. Main drawback is, to ensure chemical reversibility. Oxygen is required and therefore not environmentally independent. Costs in the range of Catalytic Bead Sensors. 4 4. Resistive Palladium Alloy Sensors: These are highly promising but still at evolving stages for maturity. Poisoning of catalyst is a serious concern and the need to use non-hydrogen specific filters prohibits its universal use. 5. Hydrogen Field effect Transistors (HFET): Uses palladium as the gate material for standard FET. Works well in limited range of 50 to 1000 ppm. Not yet completely evolved. 6. Other technologies, for example, liquid electrolyte, fuel cell and TCD sensors have important penetration in some applications. However, they do not possess selectivity, ruggedness and potential for miniaturization. TCD sensors are also very costly. A number of hydrogen ion conducting electrolytes are known such as HUP, Nafion, and Antimonic acid. H beta- alumina etc. some of which are suitable for developing a practical hydrogen gas measuring device at room temperature but suitable references have not been readily mentioned. However some references such as 1. Pb02,PbSO4 2. Pb02, PbS04, Pt-C, electrolyte 3. Fe203,FeS04 (dried) 4. CuO, Cu20 5 FeSO4, Fe2(S04)3 (Hydrated salts) 6. FeS04, Fe2(S04)3 Hydrates + electrolyte powder. Ni (OH) 2 has been used as an electrolyte, being non- acidic in nature. However self-discharge has remained a practical problem, necessitating recharge to required emf. Also the response time is slow, as compared to other hydrogen conducting ion electrolytes. Drawbacks of the Prior Art: 1. Limited dynamic range. 2. Lack selectivity. 5 3. Poor reproducibility and reversibility. 4. Subject to false alarm. 5. Tend to be slow, unreliable and difficult to use. 6. Most of the techniques are based on co-relation method. 7. When exposed to high hydrogen sensor cannot stay "high" during the whole period of exposure and drops its reading to zero thereby having negative impact on safety. 8. Co-relation method is used to measure hydrogen. Summary of the Present Invention: The main object of the present invention is to have a hydrogen sensor with stable and reversible solid reference electrode, using solid-state electrochemical cell technology for the quantitative measurement of wide variation of composition. The purpose of the present invention is to have improved solid- state electrochemical hydrogen sensor by method of contacting the novel solid reference electrode with solid electrolyte. Advantages of the Present Invention: 1. That the present invention is simple, reliable, and has specific and selective response. 2. That the present invention gives rapid response, highly reproducible and reversible. 3. That the present invention is easy to engineer, does not need recourse to mass production techniques and can be produced quite inexpensive. 4. That the present invention avoids misrepoting and false alarms. 5. That the sensor of the present invention measures hydrogen directly and specifically over a wide range of composition. 6 6. That the sensor of the present invention when exposed to high hydrogen stays high during the whole period of exposure and does not drop its reading to zero. 7. That the present invention meets the demanding criteria of robustness, simplicity, cost-effectiveness, reliability, quick, selective and specific response to target specie. 8. That the sensor of the present invention serve maximum purpose of qualitative and quantitative use. 9. That the present invention gives reliable performance over greater temperature range. 10. That the present invention is easy for installation. Description of the Present Invention: The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. The present invention relates to a hydrogen sensor using solid electrolyte, solid reference and electronic buffer assembly to cover a wide range of composition. The present invention relates to the use of a novel reference electrode which has long term stability. Accordingly, the present invention relates to a use of solid reference electrode in contact with the hydrogen ion conducting electrolyte for solid-state electrochemical hydrogen sensor by method of contacting the solid novel reference electrode with solid electrolyte. 7 The solid state hydrogen hydrogen sensor is illustrated in figure 1 of the accompanying drawing. The solid state electrochemical hydrogen sensor comprises of: Hydrogen ion conducting solid electrolyte (1) Solid reference electrode (2) Working electrode (3) The sensor is fabricated as a sandwich with respective (2&3) solid electrodes on either side of a protonic conduction solid electrolyte (1) with packing density of 98.5 to 99.8% to remain impervious to flow of gas through it. The reference electrode (2) has long term stability in contact with acidic hydrogen ion conducting solid electrolyte. The reference electrode is made up of a combination of metal and corresponding halide in powder form or slurry form in ratios ranging from 1-4 to 5-9 and brought in contact with the electrolyte surface (1) such that excellent contact is obtained between the reference electrode (2) and the electrolyte (1). The working electrolyte (3) is applied in form of slurry or sputtered or sintered. The metal O ring (4) is placed around the reference electrode (2) for deriving the separate test and reference sides in hydrogen environment. The level of contact between solid reference electrode (2) and solid electrolyte (1) can be further improved by adding a small proportion by adding a small proportion (7.5 to 19.5% ) of solid electrolyte (1) in powder or slurry form to the reference mix (metal and halide).The contact is maintained by using mechanical pressure with the help of metallic ram within a precisely machined insulating carrier made up of Teflon, Tuffhol or polymer composites such that either side of the cell system is impervious to gases from one side to the other and the entire sensor is self contained and held together for a long lasting time. The solid state hydrogen sensor system is combined with electronic buffer containing op-amps, components for uncorrupted display of data within a metallic shell. 8 Working: The above mentioned reference system when combined in a fully assembled system with Hydrogen ion conducting solid electrolyte (1) eg. HUP, nation and antimonic acid and a Pt/Pt-Ni/Pt-C working electrode (3) on the other surface or both of the electrolyte is used for accurately and quantitatively measuring and detecting hydrogen in surrounding fluid such as surrounding air or a flowing gas provided the working electrode (3) comes in contact with the fluid containing hydrogen. A solid state electrolyte (1) membrane separates a solid reference electrode from a Pt/Pt-Ni/Pt-C working electrode (3). The solid electrolyte (1) allows the measurement of difference in the chemical potentials of hydrogen constituted as two different electrodes. The emf is developed as a result of hydrogen partial pressure based on Nernst equation. H2 =2H+ + 2e (Working electrode.) 2H+ + 2e+ 2MX = 2HX + M2 (Reference electrode.) Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure or matter. The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention; which is defined by the scope of the following claims. 9 We Claim: 1. Solid State Electrochemical Hydrogen Sensor comprising of hydrogen ion solid electrolyte (1); solid reference electrode (2); working electrode (3) wherein the sensor is fabricated as a sandwich with respective solid electrodes on either side of a said protonic conduction solid electrolyte (1); the said reference electrode (2) is made up of a combination of metal and corresponding halide in powder form or slurry form in ratios ranging from 1-4 to 5-9 and brought in contact with the said electrolyte surface (1); the said working electrode(3) made up of Pt/Pt-Ni/Pt-C is applied in form of slurry or sputtered or sintered; the metal O ring (4) is placed around the reference electrode (2) for deriving the separate test and reference compartment in hydrogen environment. 2. The solid state electrochemical hydrogen sensor as claimed in claim 1 where the said reference electrode(2) is made up of metal selected from the group consisting of calcium, barium, strontium, copper, nickel and the corresponding halide is chloride, bromide or iodide. 3. The solid sate electrochemical hydrogen sensor as claimed in claim 1 wherein the said solid reference electrode(2) is used. 4. The solid state electrochemical hydrogen sensor as claimed in claim 1 wherein the said solid hydrogen ion conducting electrolyte (1) is used. 5. The solid state electrochemical hydrogen sensor as claimed in claim 1 where the said solid electrolyte (1) is any one selected from the group consisting of HUP, NAFION AND ANTIMONIC ACID 6. The solid state electrochemical hydrogen sensor as claimed in claim 1 wherein the contact between the said solid reference electrode (2) and said solid electrolyte(l) is improved by adding a small proportion 7.5 to 19.5% of said solid electrolyte(l) in powder or slurry form to the metal and halide. 10 7. The solid state electrochemical hydrogen sensor as claimed in claim 1 where said solid state electrolyte(l) membrane separates a said solid reference electrode(2) from a said working electrode (3). The said solid electrolyte(l) allows the measurement of difference in the chemical potentials of hydrogen constituted as two different electrodes; the emf is developed as a result of hydrogen partial pressure based on Nernst equation 8. The solid sate electrochemical sensor as claimed in claim 1 where the said working electrode(3) is made from any one or combination of metal selected from the group of Pt, Pt-Ni and Pt-C 9. The solid state electrochemical sensor as claimed in claim 1 where metal O ring (4) is placed around the said reference electrode (2) for deriving the separate test and reference sides in hydrogen environment. Dated this 14m day of June, 2007. 11 (CHETAN V.GUNDECHA) AGENT FOR THE APPLICANT Abstract The present invention relates to a solid state electrochemical hydrogen sensor comprising of solid ion electrolyte, solid reference electrode and working electrode. The hydrogen sensor of the present invention has stable and reversible solid reference electrode; using solid-state electrochemical cell technology for the quantitative measurement of wide variation of composition. The present invention is an improved solid- state electrochemical hydrogen sensor by method of contacting the solid reference electrode with solid electrolyte and used for detection of hydrogen.

Documents:

1120-mum-2007-abstract.doc

1120-mum-2007-abstract.pdf

1120-MUM-2007-CLAIMS(AMENDED)-(28-11-2011).pdf

1120-MUM-2007-CLAIMS(AMENDED)-(9-4-2012).pdf

1120-MUM-2007-CLAIMS(MARKED COPY)-(9-4-2012).pdf

1120-mum-2007-claims.doc

1120-mum-2007-claims.pdf

1120-mum-2007-correspondence(2-6-2008).pdf

1120-MUM-2007-CORRESPONDENCE(30-10-2009).pdf

1120-MUM-2007-CORRESPONDENCE(9-4-2012).pdf

1120-MUM-2007-CORRESPONDENCE(IPO)-(30-10-2009).pdf

1120-mum-2007-correspondence-received.pdf

1120-mum-2007-descripiton (complete).pdf

1120-mum-2007-drawing(14-6-2007).pdf

1120-mum-2007-form 1(14-6-2007).pdf

1120-MUM-2007-FORM 1(30-10-2009).pdf

1120-MUM-2007-FORM 13(28-11-2011).pdf

1120-mum-2007-form 18(2-6-2008).pdf

1120-mum-2007-form 3(14-6-2007).pdf

1120-mum-2007-form 9(5-7-2007).pdf

1120-mum-2007-form-1.pdf

1120-mum-2007-form-2.doc

1120-mum-2007-form-2.pdf

1120-mum-2007-form-26.pdf

1120-MUM-2007-OTHER DOCUMENT(30-10-2009).pdf

1120-MUM-2007-POWER OF ATTORNEY(28-11-2011).pdf

1120-MUM-2007-REPLY TO EXAMINATION REPORT(25-8-2011).pdf

1120-MUM-2007-REPLY TO HEARING(11-11-2011).pdf

1120-MUM-2007-REPLY TO HEARING(28-11-2011).pdf

1120-MUM-2007-SPECIFICATION(MARKED COPY)-(25-8-2011).pdf