RU2194975C2 - Solid-state electrochemical gas analyzer for finding-out acetylene - Google Patents

Abstract

FIELD: check of content of acetylene in closed and open spaces, as well as in vapor of transformer oil which is indicative of defects in high-voltage transformers. SUBSTANCE: used as working electrode is porous carbon matrix with chemical nickel applied over entire volume. Powder-like nickel oxide is used as comparison electrode and proton-conducting solid electrolyte is used as electrolyte. EFFECT: enhanced efficiency; low cost. 2 dwg

Description

 The invention can be used in monitoring the acetylene content in closed and open spaces, as well as in transformer oil vapors, which is a sign of defects that occur during operation of high voltage transformers.

The inventive electrochemical gas analyzer for determining acetylene in closed and open spaces, as well as in transformer oil vapors, allows you to work at temperatures from 0 to 40 ^o C, contains a working electrode, which is a porous carbon matrix with chemical nickel deposited on it throughout the volume, proton-conducting solid electrolyte and, as a reference electrode, nickel oxide.

 The prior art in this area is characterized by publicly available information below.

The most widely used for determining gas concentrations (among which acetylene can be determined) in exhaust and process gases, as well as in air, have been obtained by catalytic gas analyzers. The use of such gas analyzers requires auxiliary devices, in particular a flame furnace or a combustion chamber. For the catalytic combustion of a hydrocarbon (for example, acetylene), a flame furnace with a nominal temperature of 365 to 560 ^o C depending on the ignition temperature of the measuring gas is used, and a palladium contact is used as a catalyst [1].

The disadvantages [1] are:
a) the availability of auxiliary devices for the combustion of the measuring gas, i.e. gas analyzer operation at high temperature;
b) the use of palladium related to platinum metals, which significantly increases the cost of such a device.

 Also known are semiconductor sensitive elements designed to operate as part of leakage control devices for explosive and toxic substances of a reducing type (in particular hydrocarbons).

The method of manufacturing semiconductor sensitive elements includes the following operations:
1) winding a heat-resistant spiral of platinum wire, and this operation is controlled using a measuring microscope;
2) the formation on this spiral of a ceramic gas-sensitive body by applying and calcining a semiconductor material, which is an indium hydroxide gel treated with nitric acid.

To stabilize the gas-sensitive properties, the elements are calcined at 850 ^o C for 4 hours [2]. The basis of the operation of such a device is a change in the electrical conductivity of a ceramic body at certain temperatures under the influence of a reducing gas.

The disadvantages [2] are:
a) the use of noble metals (platinum), which significantly increases the cost of the gas analyzer;
b) the operation of this device at elevated temperatures.

 Closest to the claimed invention in technical essence (operation of the device at room temperature) is a device for the continuous determination of acetylene formed under the action of glow discharges in high-voltage devices with oil insulation. Gaseous products by diffusion through a semi-permeable membrane made of polytetrafluoroethylene made in the form of a hose spiral are sent to a piping system filled with an inert gas. The system contains a gaseous tube with an adsorbent for acetylene filled with a colored indicator [3]. The principle of operation of such a device is based on a color change of the indicator upon its contact with acetylene.

 The disadvantage of [3] is only a qualitative analysis for the content of acetylene. The present invention allows to determine the quantitative content of this gas, including in high-voltage devices.

 The aim of this invention is to obtain quantitative results of the concentration of acetylene, the operation of the gas analyzer at room temperature and ensuring the simplicity and accessibility of measurements at a relatively low cost device.

 The essence of the invention lies in the fact that a porous carbon matrix with chemical nickel deposited on it throughout the volume was used as a working electrode. The reference electrode was powdered nickel oxide; the proton-conducting solid electrolyte was the electrolyte.

 In FIG. 1 shows a section of an electrochemical gas analyzer. Where in FIG. 1 marked: down conductors 1, working electrode 2, solid electrolyte 3, cell body (fluoroplastic) 4, gasket 5, reference electrode 6.

 New in the proposed technical solution is that a porous carbon matrix with chemical nickel deposited on it throughout the volume was used as a working electrode, powdered nickel oxide served as the reference electrode, and the proton-conducting solid electrolyte was the electrolyte.

 The electrochemical gas analyzer operates in potentiometric mode. Through the gas analyzer, a signal is obtained for the gas content in the form of an emf in a given concentration range. An analytical signal of the dependence of the emf on the concentration of acetylene is used to construct the corresponding calibration curve, which determines the studied gas concentration (figure 2.).

 As a result of approximation of the experimental data, the following formula was obtained: ΔЕ = 29.92 + 5.25 logC.

Bibliography
1. VEB Junkalor.//JUNKALOR-Prozessgasanalysatoren. - 1985.

 2. Copyright certificate of the USSR 1614646 A, G 01 N 27/12, 1989.

 3. Switzerland, patent 667740, 1989.

Claims (1)

 An electrochemical gas analyzer for determining the concentration of acetylene, containing a working electrode, a reference electrode and an electrolyte, characterized in that it operates at room temperature and a porous carbon matrix with chemical nickel deposited on it throughout the volume is used as the working electrode, powdered nickel oxide serves as the reference electrode, A proton-conducting solid electrolyte was used as an electrolyte.

Images