Solid electrolyte sensor for measurement of oxygen concentration in gases and molten metals

IPC classes for russian patent Solid electrolyte sensor for measurement of oxygen concentration in gases and molten metals (RU 2489711):

G01N27/406 -

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Solid electrolyte sensor for measurement of oxygen concentration in gases and molten metals includes a solid electrolyte made in the form of a test glass, a reference electrode, an internal current collector from the reference electrode, a protective cover that is equipped with a contact ring and serves as an external current collector. According to the invention, the sensor is equipped with an additional measuring electrode with a current collector; the electrode is located in middle part of outside surface of the solid electrolyte glass, and the protective cover has through openings for passage of analysed gas to the measuring electrode surface.

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FIELD: measurement equipment.

SUBSTANCE: solid electrolyte sensor for measurement of oxygen concentration in gases and molten metals includes a solid electrolyte made in the form of a test glass, a reference electrode, an internal current collector from the reference electrode, a protective cover that is equipped with a contact ring and serves as an external current collector. According to the invention, the sensor is equipped with an additional measuring electrode with a current collector; the electrode is located in middle part of outside surface of the solid electrolyte glass, and the protective cover has through openings for passage of analysed gas to the measuring electrode surface.

EFFECT: invention provides the possibility of performing measurements both of oxidation of molten metal and oxygen content of gas phase above molten metal; simpler design of the sensor and higher measurement accuracy.

1 dwg

The invention relates to analytical techniques, in particular to sensors designed for the analysis of gas media and metallic melts on coloradocolorado.

Known potentiometric sensors for measuring the concentration of oxygen in gas media, manufactured using a solid electrolyte having oxygen-ion conductivity. Thus, the known electrochemical sensor for continuous measurement of oxygen concentration in gas media (A.S. USSR №1203427, publ. 07.01.1986 g) [1]. The sensor contains a tube of solid oxide electrolyte, a closed elastic cylinder. On external and internal surfaces of tubes placed the measuring and reference electrodes with a current collector, and a guide tube located along the axis of the tube in its inner cavity. In addition, the sensor includes a camera, which together with tube feeding and discharge of the reference gas and the cavity of the sensor forms zamknutu system. On-hook reset reference gas has a circulation booster reference gas. Known sensor capable of analyzing the content of oxygen gas mixture.

Known sensor for detecting the content in molten copper (RF patent 2062460, publ. 20.06.1996,) [2]. The sensor is a graphite rod, is provided with an elastic plate attached to patentregistered, the lower end of which is connected to the graphite rod, the upper end is configured to a fixed pin and a part of the side surface along the entire length of the graphite rod applied protective refractory coating based on carbon-free materials. Work known sensor [2] is based on the principle: the higher the oxygen content in the melt, the more intense will be the reaction of oxidation of carbon and the greater the deviation of a graphite rod, the bending of elastic plates and tensile stresses in the strain gauge. Sensor [2] is characterized by complexity and uncertainty of the design, the need for calibration and low accuracy of measurement due to dependence on the quality and composition of a graphite rod.

Known sensor oxidation of the metal melt (A.S. USSR №830228, publ. 14.01.1981,) [3]. The sensor comprises a solid electrolyte made in the form of tubes, a reference electrode, an inner current collector with a reference electrode, protective cover that serves as an outer current collector, in this case provided with a contact ring located at the bottom of the case and is made from an inert material composition, wt.%:

CrO	40-50
RO	20-35
CaO	20-35,

where R is a lanthanide.

The possibilities of the known sensor [3] is limited to the measurement of oxygen concentration only in metal melts.

Declared the solid electrolyte sensor for measuring oxygen concentration in gases and metal melts containing made in the form of a tube of solid electrolyte, a reference electrode, an inner current collector with a reference electrode, provided with a contact ring protective cover that serves as an outer current collector. The sensor differs in that it is equipped with additional measuring electrode current collector, and the electrode is located in the middle part of the outer surface of the solid electrolyte tube and the protective cover has a through window for the passage of the sample gas to the surface of the measuring electrode.

The essence of the claimed invention is as follows. The supply of additional sensor measuring electrode current collector, while the electrode is located in the middle part of the outer surface of the solid electrolyte tube and the protective cover has a through window for the passage of the sample gas to the surface of the measuring electrode, leads to intensive gas exchange between the atmosphere and the outer surface of the sensor, and the electrode condition is yavlyaetsya oxygen potential corresponding to coloradocolorado gas atmosphere above the melt. Coloradocolorado gas atmosphere largely determines Coloradocolorado the melt. Before diving into the melt, the sensor is heated in a gas environment and temperature reaches the analyzed melt. On the reference electrode of the sensor is installed equilibrium oxygen potential corresponding to the partial pressure of oxygen in the reference gas, e.g. air. Between the reference electrode and the melt is set to the potential difference E1, and between the reference electrode and the additional measuring electrode there is a potential difference E2. By measuring the values of E1 and E2, can be defined as the activity of oxygen in molten metal, and coloradocolorado gas atmosphere above the melt.

A new technical result achieved the claimed invention is the ability to measure both the oxidation of molten metal, and coloradocolorado gas phase above the melt, and also to simplify the design of the sensor and increase the accuracy of measurement.

The invention is illustrated in the drawing, which shows the inventive sensor. The sensor contains the solid electrolyte tube 1, the reference electrode 2, the inner current collector with the reference electrode 3, an additional ISM the measuring electrode 4, located in the middle part of the outer surface of the solid electrolyte tube 1, the current collector with him - 5, protective metal case 6, which is simultaneously an outer current collector potential of the analyzed melt. Case 6 provided with a contact ring 7. The solid electrolyte tube 1 are sealed and connected with the protective cover 6 heat-resistant sealant 8. The cover 6 has a through window 9 for the passage of the sample gas to the surface of the measuring electrode 4. The sensor immersed in the analyzed metal melt 10, has two voltage meter - INF-1 and INF-2 for measuring the potential difference of the corresponding electrochemical circuits, namely IN-1 - for measuring the potential difference between the collector of the reference electrode 3 and the metallic melt 10, and INF-2 between the collector of the reference electrode 3 and the measuring electrode current collector 4. The sensor is in operation in the high temperature field, which creates the analyzed gas medium and the metal melt.

For measurements, the sensor is immersed in the analyzed molten metal over which is the appropriate gas atmosphere (protection, restoration, oxidation). As noted above, largely coloradocolorado gas atmosphere determines coloradocolorado sa is on the melt. Because gas atmosphere and the melt are at elevated temperatures, the sensor is heated to melt temperature. On the reference electrode of the sensor is installed equilibrium oxygen potential corresponding to the partial pressure of oxygen:

$φ (e . e .) = R T / 4 F \ln ρ O_{2}, (1)$

where:

φ (EE) - the potential of the reference electrode;

R is the gas constant (1,9873 cal/deg*mol);

T - melt temperature in degrees Kelvin;

ρO₂- partial pressure of oxygen at the reference electrode, PA.

The oxygen potential of the analyzed melt can be expressed by the equation:

$φ (a . p .) = R T / 4 F \ln a o, (2)$

where:

φ (A.R.) is the potential of the analyzed melt;

AO activity of oxygen in the analyzed melt.

Between the reference electrode and the melt ustanavlivaetsya potentials:

$E 1 = R T / 2 n F L n φ (e . e .) / φ (a . p .) = R T / 2 n F L n ρ O_{2} / a o, (3)$

where:

E1 is the potential difference (MV);

n is the valency of oxygen is 2;

F - Faraday constant (96496).

Value (E1) is determined by equation (3) the oxygen activity in the analyzed melt and is measured with a voltage meter IN-1.

Between the reference electrode and the measuring electrode there is a potential difference E2:

$E 2 = R T / 2 n F L n φ (e . e .) / φ (a . p .) = R T / 2 n F L n ρ O_{2} / \underline{ρ O2}, (4)$

where:

$\underline{ρ O_{2}}$ - the partial pressure of oxygen in the analyzed gas environment;

Value (E2) is determined according to equation 4 the partial pressure of oxygen in the sample gas and is measured by a voltage meter IN 2.

Thus, by measuring the values of E1 and E2, can be defined as the activity of oxygen in molten metal, and coloradocolorado gas atmosphere above the melt. When this sensor is characterized by a simplified construction and increased accuracy of measurement.

The solid electrolyte sensor for measuring oxygen concentration in gases and metal melts containing made in the form of a tube of solid electrolyte, a reference electrode, an inner current collector with a reference electrode, provided with a contact ring protective cover that serves as an outer current collector, characterized in that the sensor provides additional measuring electrode current collector, and the electrode is located in the middle part of the outer surface of the solid electrolyte tube and the protective cover has a through window for the passage of anal is projected gas to the surface of the measuring electrode.