SU1022035A1 - Pickup for measuring activity of oxygen in metal - Google Patents

Abstract

A SENSOR FOR MEASURING OXYGEN ACTIVITY IN METAL, comprising a housing made 8 as a cylinder and being simultaneously a current collector, in which a solid eectrolyte is located, characterized in that the current collector is made of graphite, fireclay and binder composition, wt.%: GraphitbO-VO Chamot15-30 Binder Else and the grain size is: chamotte. 1.0-3.0 mm; graphite 0.05-0.20 mi.

Description

The invention relates to ferrous metallurgy, namely to the measurement of the oxygen activity in liquid steel using the EMF method of a concentration element; , and can be used to control steelmaking technology in industrial units. "A sensor is known for measuring the oxygen activity in metals, containing a body in the form of a refractory tube made of solid electrolyte, in which a reference electrode and a silver puller with silver embedded in it with silver insoluble material CO are located. The disadvantage of this sensor is the high cost and insufficient measurement accuracy. The closest in technical essence to the present invention is a sensor for measuring oxygen activity in a metal, comprising a body made in the form of a cylinder and being simultaneously a current collector in which a solid electrolyte 2 3 is located. A disadvantage of a graphite current collector is its fast dissolution in steel. Studies show 4j: with a wall thickness of graphite glass of 5 mm, the duration of its dissolution in liquid steel is 2 minutes. The rate of dissolution of graphite is 2.5 mm / min. For this reason, the graphic current collector cannot be used to measure the oxygen activity in liquid steel, since rapidly dissolving graphite deoxidizes the steel. The aim of the invention is to improve the measurement accuracy and increase the service life. This goal is achieved by the fact that in the sensor for measuring the active oxygen in the metal, comprising a housing made in the form of a cylinder and being simultaneously a current collector, in which a solid electrolyte is located, the current collector is made of graphite, chamotte and St. of the composition, wt.%: Graphite 60-85 Shamot15-30 Binder Rest and the grain size is: chamotte 1.0-2.0 mm; graphite 0.05-0.20 mm. The drawing shows a device for measuring the activity of oxygen in a liquid metal, a general view. 15 . , 2 The sensor consists of a solid electrolyte from stabilized zirconium dioxide in the form of a cap 1, which is protected by an adund tube 2 and a stripper 3 in the form of a graphite chamfer tube containing 60-85% chamotte with grain size 1.0-3.0 mm and 1530 graphite with a grain size of 0.050, 2 mm. Inside the kollachka of solid electrolyte is placed a two-channel alundum tube in which thermocouple 5 is located. From the thermocouple and the current collector, conclusions 6 are made on the contact rings 7 of connector 8, in the latter there is an opening 9 for the air supply. Between the contact rings there are insulating fluoroplastic laying 10. The air outlet from the solid surface of the electrolyte in the connector made a hole 11. The bottom of the sensor is put on a graphite glass soluble in steel 12. The sensor works as follows. 2-3 minutes after the sensor is immersed in a metal, a graphite cup dissolves in steel and the metal begins to contact solid electrolyte 1 and current collector 3. Air is used as a reference gas, which is supplied through hole 9 and discharged through hole 11. Due to the difference in oxidizing gas potential of the media on both sides of the solid electrolyte 1 on the walls of the potential jump occurs. On the inside of the solid electrolyte, the potential is removed from. using one of the wires of the platinum – rhodium thermocouple 5, and the outside side through the liquid metal using a current collector 3. Using the potential difference, the oxygen activity is calculated. The duration for measuring the oxygen activity in the steel sensor application in open-hearth furnaces will be at least min for the first case (15 graphite) and at least 50 min for the second case (301 graphite). The lower limit of the content of graphite in a graphite chamfer is chosen for reasons of ensuring reliable electronic conductivity. With a lower content of graphite, a film of mixed conductivity is formed. The upper limit of the content of graphite in a graphite chamfer is chosen for reasons of an acceptable duration of continuous measurement of activity, oxygen. With a higher content of graphite, the dissolution rate of the graphite chamfer increases dramatically and at 0 graphite t0, -0.5 mm / min. The content in the graphite chamfer is determined by the content of graphite. In addition to these two ingredients, only a binder material, such as coal tar pitch or refractory clay, is present in the graphite chamfer. The particle size distribution of graphite chamotte corresponds to the goal. When using chamotte grains with a particle size of less than 1 mm, when exposed to liquid steel, a layer of fireclay with mixed conductivity is formed. Experiments show that in this case there arises an additional .EMF, which distorts the results of Vlmeasures. When the grains of chamo.ta are larger than 3 mm, the rate of dissolution of graphite chamotte increases, and the dissolution is not ordered (not layered) in character. The same happens when using graphite with a grain size of more than 0.2 mm. When developing a sensor, it is necessary to prevent the steel of carbon from the graphite chamfer in the zone measuring the activity of 10 5 oxygen to be prevented. When the content of graphite in graphite chamfer 15 / is, the rate of entry of graphite into steel is (current diameter 33 mm, height tO mm) about 0.07 g / min, and with graphite 30 it is about 0.2 g / min. Compared with the rate of carbon oxidation, for example, in a 250-marten furnace, which is in the range of 0.5-10 - 1.0-10 g / min. T, this value is negligible. The operability of the sensor and the absence of deoxidation of steel with carbon in the measurement zone has been proven experimentally. Oxygen activity in steel was measured in an open-hearth furnace for 1.0-t, 5 h (5 runs) h in an intermediate ladle UNRS for 2.0-3.0 h (5 runs) at the same time by two sensors, which differed in current collectors. In one of them, the reference current actinometer was used in all the experiments in a silver current collector, the second ddtchik (experienced) was equipped with graphite-chambered taker. The test results of the sensors with current collectors of different composition are given in the table.

The rest is coal tar pitch.

5 1022035

The sensors were located at a distance of 1 ini of graphite in liquid steel, the Schadrug grain from each other. During the entire period of time, interconnected with each other, - measurement smears, the difference in readings is liquid metal, exposing a new

sensors did not exceed 9 that count-layer graphite chamfer, and so o6pa30h

satisfactory for measurements; 5 conserved electron conductivity

similar kind. material.

Thus, in graphite chambered, the use of a sensor in the production of 60-85 chamotte with a steel value in open-hearth furnaces has been reduced by 1.0–3.0 mm and 15–30% of graphite, which reduces the duration

the size of the grains is 0.05-0.20 mm of detection by 2%, reduce the consumption of ferro-manganese, a new property, which is lost by 6%, reduce the head trim

: it is in that. measure solution-0.5.

Claims (1)

SENSOR FOR MEASURING OXYGEN ACTIVITY IN METAL, comprising a body made in the form of a cylinder and simultaneously a current collector, in which a solid electrolyte is located, characterized in that, in order to increase measurement accuracy and increase service life, the current collector is made of graphite, chamotte and a binder composition, weight D: G raffite Chamotte Binder; 60-80 15-30 The rest of the grain size is: fireclay. a 1.0-3.0 mm; graphite 0.05-0.20 mm. 1022035 ²