SU1642328A1 - Dust and soot determinator - Google Patents

Abstract

The invention relates to a measurement technique, can be used to measure the electrical characteristics of an aerosol in the atmosphere, in automatic and operational systems for controlling the emission of dust, soot and aerosol into the atmosphere. The purpose of the invention is to increase measurement accuracy, reduce energy intensity and increase safety. A dust and soot sensor containing a cylindrical measuring electrode, a screen coaxial with it, additionally contains two annular auxiliary electrodes, spaced by a fixed distance along the flow, with the measuring and auxiliary electrodes having a dielectric ring on the flow side. The ratio of the length of the measuring electrode to its diameter is not less than four, while the length of the cylinder of the measuring electrode is less than the length of the screen by two diameters of the measuring electrode. In addition, the measuring electrode is connected to the input of a series-connected amplifier, integrator, cube-building function block, scale-up amplifier, multiplier and indicator, and one of the outputs of the velocity meter is connected to the second input of the multiplier, to the input of which two annular auxiliary elec- trons are connected. sort, and the second output of the speed meter connected to the indicator, 1Cp. f-ly, 1 ill. TSNYi. four-. GO w to 00

Description

The invention relates to measuring the concentration of particles of dust, soot and other aerosols, and can be used in various fields of science and technology, for example, to measure the electrical characteristics of aerosol in the atmosphere in automatic and operational systems for controlling the emission of dust, soot and aerosol into the atmosphere.

The aim of the invention is to increase the measurement accuracy, reduce the energy intensity and increase the safety of the sensor.

The drawing schematically shows a dust and soot sensor.

The sensor contains a measuring cylindrical electrode 1, two annular auxiliary electrodes 2, a screen 3 located coaxially with respect to the measuring electrode of a dielectric ring 4, an electrical signal amplifier 5, an integrator 6, a cube functional unit 7, a scale amplifier 8, a multiplier 9, indicator 10 meter 11

speed.

.. “-

Gas flow at a rate v after-

passes through the inlet metal nozzle, the first annular auxiliary electrode 2, from the direct deposition of gas particles by a dielectric ring 4, a small metallic annular spacer, the measuring cylindrical electrode 1 also protected from the flow of the ring 4, then through the spacer, the auxiliary electrode 2 and the output metal -. Lylic pipe. The case of sensitive elements is protected by a coaxially arranged screen 3.

The sensor works as follows. The signal from the measuring electrode 1 is fed to the input of the amplifier 5 signals. The amplified signal is integrated by integrator 6. The integration time can be set constant for a given measurement system. POS le integration signal enters the functional block 7 erection in the cube. In the scale amplifier 8, the operation of changing the signal to a constant value is implemented. The signal then goes to the input of the multiplier 9, in which the signal is adjusted to the flow rate (so that the signal does not depend on speed. To do this, a speed meter 11 is installed in the sensor, in which a signal proportional to the flow rate is generated impulses of the electric field on the ring auxiliary electrodes 2, the signal from which is fed to the input of the velocity meter.The signal from the output of the multiplier 9, proportional to the concentration, is fed to one of the indicator inputs, to the second input to torogo enters sig nal output from the speed meter 11.

The proposed dust and soot sensor can be implemented both in a portable and in a stationary version (in the latter case it is a part of any ventilation system).

The charged particles, moving with the flow, sequentially induce an electric charge on the first annular

auxiliary electrode 2, a measuring cylindrical electrode 1 and a second ring auxiliary electrode 2. Virtually all flows in ventilation systems and emissions are turbulent, so the signal at the input of amplifier 5 is a pulse curve with random pulse amplitudes. Each pulse characterizes turbulence, the dimensions of which are determined by the input dimensions of the ventilation system and the flow velocity. In some cases, the size of the turbulence is related to the ejection diameter and the frequency of the process.

According to preliminary experiments established the dependence of the form

With AL3 + B,

where C is the technological concentration

dust mg / m;

L is a quantity proportional to the area of the envelope (the dimension is arbitrary); A and B are constant depending on

properties of the measuring system In accordance with the above formula, the signal from the output of amplifier 5 is integrated by integrator 6, with this finding a number proportional to the area covered by the process envelope over a certain time.

In function block 7, the number s proportional to the area is cubed, and in the scale amplifier 8 constant coefficients A and B are entered. In some systems, the gas flow rate is not a stationary value, then it is necessary to introduce a correction for the rate of change. In the sensor, such a correction is introduced by a standard velocity gauge 11, the input of which receives a signal from two annular auxiliary electrodes.

The velocity meter operates according to the principle of coincidence of pulses associated with the passage of turbulence through the first and second auxiliary rings. With a known and fixed distance between the rings, the speed is determined by the coincidence time of the same pulses. In multiplier 9, the signal is normalized by the magnitude of the speed so that it is independent of speed. Indicator 10 records two values — particle concentration and flow rate.

Compared to known devices, the sensor does not affect the parameters, does not distort the distribution of the flow velocity. There are no elements installed in the flow path, while, like existing devices, there are elements (needles, rings) of jet charging that distort the flow. When charging, the equilibrium state between the particles is disturbed, the recombination process increases, the current increases by the device case and the effect of sticking of particles to the case of sensitive elements, which ultimately reduces the efficiency of the devices, reduces the accuracy of their work. The proposed sensor is free from these disadvantages, since it has no charge device.

To increase the measurement accuracy and reduce the effect of electric fields on the sensing element, the cylindrical measuring electrode is made two diameters shorter than the screen. Moreover, the screen is electrically connected to the input and output nozzles, which also serve as guard electrodes.

The relationship between the length and diameter of the cylindrical measuring electrode is essential. With a length to diameter ratio of less than three, the electrode does not integrate the electric field of turbulences, but highlights each individually. The resulting field causes the response of the electronic system in the form of pulses of large amplitude and duration. It is not possible to distinguish the distinctive features associated with the concentration of dust; turbulence behaves like a solid charged body. When the ratio of the length of the sensing element to the diameter is more than three (the device is more than four), the sensing element, as an integrator, smoothes the process of passing turbulences, therefore, signs characterizing concentration are highlighted (in particular, this sign is the area under the process envelope). A further increase in the ratio does not add to the efficiency of extraction of the useful signal, which characterizes the concentration of cpc and soot.

The aerosol and dust charging device requires high voltages, which is a significant disadvantage of all existing devices. When working and setting up devices with high voltage charging, it is necessary to comply with the requirements for increased hazardous works. RF of the proposed sensor does not require such work, which is especially important when using an autonomous method of measuring and performing the sensor in a portable version.

A wide range of sensors is used when using it in automated systems for controlling the release of harmful substances into the atmosphere.

F, about rmu l and inventions

Claims (2)

1. A dust and soot sensor, soda gas measuring cylindrical eicarod, coaxially located with a screen, characterized in that, in order to increase measurement accuracy, reduce energy intensity and increase safety, the sensor additionally contains two annular auxiliary electrodes spaced by a fixed distance along on the flow side, the measuring and auxiliary electrodes are equipped with coaxially arranged dielectric rings, and the ratio of the length of the measuring electrode to its diameter is Four, and the length of the cylinder of the measuring electrode is less than the length of the screen by two diameters of the measuring electrode. 2. The sensor according to claim 1, characterized in that the measuring electrode is connected to the input of a series-connected amplifier, integrator, cube building functional unit, large-scale amplifier, multiplier and indicator, and one of the outputs of the speed meter is connected to the second input of the speed meter, which are connected to two annular auxiliary electrodes, and the second output of the speed meter is connected to the indicator.