SU593164A1 - Sensor for measuring dust resistivity - Google Patents

Description

one

The invention relates to the study of the physical properties of substances, in particular, the determination of the specific electrical resistance of powdered materials, dusts, and ash, and can be used in the chemical and petrochemical industries, heat and power, cement and metallurgical industries, and the building materials industry.

The invention is intended for use in laboratories of research institutes and enterprises, occupying them by researching the operation of electrostatic precipitators, their calculation, design, and development.

A device for determining the specific electrical resistance of dust is known. The sensor of this device consists of two comb collecting electrodes located strictly in the same plane. The gap formed between the combs is clogged with dust by the electric field created by the corona electrodes. The measurement of the resistance of dust in the gap is made with a terahommeter.

In this sensor, the electric field closes on the surface of the comb electrodes, so the dust enters the gap mainly due to inertial forces. There are voids in the gap, the density of dust in the gap is less than the density of the dust layer on the electrode surface,

which leads to a distortion of the measurement of electrical resistance. The absence of guard electrodes increases the measurement error. The error in measuring large resistances is ± 20%.

The closest technical solution to this invention is a sensor for measuring the electrical resistivity of dust, comprising a housing and concentric, high-voltage, measuring and guard electrodes 2 concentric with each other.

The disadvantage of such a sensor is low measurement accuracy.

In order to improve the measurement accuracy, the high-voltage electrode is provided with a funnel-shaped bottom with a nozzle and a device for reciprocating mixing, with respect to the measuring and guard electrodes, and the upper end of the electrode is sharpened.

The formation of a layer of dust on the measuring and guard electrodes is carried out in the electric field of the corona discharge during the non-period of suction through the internal cavity of the dust-gas sensor, while the high-voltage electrode is in the lowered position.

A layer of dust on the measuring and guard electrodes forms slightly more than the required thickness. When the high-voltage electrode is lifted, an extra layer of dust is cut off. The resistance of dust in the annular gap is determined by the known method of a voltmeter and an ammeter.

The drawing shows a general view of a sensor for measuring the electrical resistivity of a layer of dust, a section.

The sensor includes a housing 1, a housing cover 2, a base 3, pillars 4, a protective casing 5, a measuring electrode 6, an upper guard electrode 7, a lower guard electrode 8, a high voltage electrode 9, insulator rings 10, 11 and 12, pillars 13, a leash 14, an insulator 15, a corona electrode 16, an inlet 17, an outlet 18, a meter window 19, terminals 20 and 21, a coil for electrical heating 22.

The sensor works as follows.

The high voltage electrode 9 is in the lowered state and is connected to housing 1 by means of terminal 21, and electrode 6 is also connected to housing through terminal 20. Case 1 is connected to the plus terminal of a high voltage source. The corona electrode 16, mounted on an insulator 15, is connected to the negative terminal. The inlet 17 is connected to a source of dusty gas or the inlet duct of the electrostatic precipitator, and the outlet 18 is connected to a source of discharge. After switching on the high voltage source, a layer of dust is formed on the measuring electrode b and the guard electrodes 7 and 8 under the action of an electric field and a corona discharge. The process of forming a layer of dust is observed through a viewing window 19. After a layer of dust forms on the measuring 6 and guard 7 and 8 electrodes, slightly exceeding the width of the annular gap between the electrodes 6 and 8, the source voltage is turned off.

The high-voltage electrode 9 is lifted to the upper position with the help of a driver 14 connected by pillars 13 with an insulating ring 12. The dust from electrodes 6, 7 and 8 is cut off by the pointed end of electrode 9. Electrode 9 is fixed in a raised position. The sensor electrodes are connected to a DC source. The high voltage electrode 9 is connected to the positive terminal of the current source by means of the terminal socket 21.

The microammeter is connected to the terminal jack 20 and the negative terminal of the current source. Sensor body 1 and negative terminal are grounded. The voltmeter is connected to the negative and positive terminals of the source. When voltage is applied to electrodes 6 and 9, a current flows through the layer of dust in the annular gap of electrodes 6 and 9, which is detected by a microammeter. Currents passing through the guard electrodes 7 and 8 are diverted to ground.

The resistance of the dust layer in the annular gap, taking into account the structural characteristics of the sensor, is determined by the known calculation method from the magnitude of the current recorded by the microammeter and the voltage applied to the electrodes 6 and 9.

When obtaining the dependence of the electrical resistance of dust on temperature change, the electrical heating of the device is carried out by a spiral 22. The temperature inside the device is measured by a thermometer.

The use of the sensor makes it possible to increase the sensitivity by increasing the area of the measuring electrode and to study representative dust samples.

The electrical resistivity of the dust layer formed on the measuring electrode in the electric field of the corona discharge will correspond to the resistance of the dust layer on the precipitation electrode of the real electrostatic precipitator, which is important for designers of electrostatic precipitators.

Claims (2)

1.Staub 26 (1966) No. 1, p. 11-14. 2. The instrument “Cyclone-1, M., GOSIMTI, 1968. nineteen 18 ten