SU1652756A1 - System for automatic control of carbon content in fly ash of pulverized-coal fired boiler unit - Google Patents

Abstract

The aim of the invention is to improve the accuracy of control and system reliability. This is achieved by the fact that the cyclone 3 is equipped with a pipe 11 with an electromagnetic valve 12 connected to the atmosphere, and in the L-shaped exhaust pipe 4 there is a waste sample discharge pipe, made in the form of a rectangular bend and equipped with a drive 18 for vertical movements. Using this pipe, cyclone 3 is periodically cleaned of contamination when valve 12, which connects the internal cavity of the cyclone with the atmosphere, is open. 3 il.

Description

Fig f

The invention relates to the determination of the physicochemical properties of bulk materials, in particular, to the design of a complex for controlling the carbon content in the ashes of thermal power plants operating on solid fuels, and can be used both in the power industry and in other areas of the national economy.

The purpose of the invention is to improve the accuracy of control and reliability of the system.

FIG. Figure 1 shows a diagram of the system for automatic monitoring of carbon content in coal ash of a pulverized coal boiler; in fig. 2 - a cyclone with a discharge pipe for the spent sample in its upper position, section: in FIG. 3 - the same, with a discharge nozzle in the lower position.

The system contains ash collecting tubes 1 installed on the same level in the boiler duct, equipped with cork taps 2 and connected to the cyclone 3 with the exhaust pipe 4 of an L-shaped form connecting the cyclone 3 by means of a gas collecting pipe 5 and its vertical section 6 with an ejector 7. Ash collector 8 cyclone 3 is connected to a capacitive sensor 9, above which a probe 10 level sensor is mounted. Cyclone 3 is additionally equipped with a pipe 11 with a solenoid valve 12. To remove the sample from sensor 9, use the waste sample discharge pipe, made in the form of a rectangular bend 13 installed inside the cyclone 3 and exhaust pipe 4, while its vertical part 14 is located coaxially with capacitive sensor 9 The horizontal part 15 is end-provided with a branch pipe 16 with a flange 17, and the elbow 13 is provided with a drive 18 for vertical movement. A sample compactor 19 is rigidly attached to sensor 9, and electrodes 20 and 21 of sensor 9 are attached to insulating material base 22, connected to high frequency generator 23, and connected to measuring unit 24 and recording unit 25. The sample level sensor 10, the solenoid valve 12, the actuator 18 and the vibration compactor 19 are electrically connected to the control unit 26.

The system consists in collecting ash from the flue, accumulating a given volume as a sample in a capacitive sensor, compacting the sample in the sensor using vibration, continuously measuring the generator frequency during ash compaction, detecting the maximum frequency of the generator during compaction, determining the maximum frequency of the carbon content in the ashes according to the equation of the experimentally established dependence of the generator frequency on the carbon content in the ash and simultaneously with the determination of the carbon content in the ash alenia test

from capacitive sensor.

The starting position of the system for starting work is such that knee 13 with nozzle 16 takes up its upper vertical position (Fig. 2), taps 2 are open, and valve 12 of nozzle 11 is closed, while cyclone 3 is pneumatically connected via exhaust pipe 4 and elbows $ 1 with a gas collecting pipe 5, and through the ash extraction pipes of the 1st gas flue boiler unit.

When you turn on the system to work include the supply of compressed gas to the ejector 7, under the action of which at the inlet of the ejector 7, in the gas collection pipe 5, the exhaust pipe 4,

0 a cyclone 3 and ash collection tubes 1 create a vacuum, and the flue gases, together with the ash from the gas duct, flow through the tubes 1 into the cyclone 3. The flue gases are freed from the ash and through the exhaust pipe 4,

5, the bend 13 with the nozzle 16 and the gas discharge pipe 5 enters the ejector, from where it goes back to the gas duct together with the working gas. Under the influence of gravity, ash particles descend along the cyclone 3 and through

0 ash remover 8 enters the capacitive sensor 9, in which ash is accumulated to the level of the electrodes of the sensor 10, from which the control signal comes to the equipment operation control unit 26

5 systems in a given sequence. As a result, block 26 includes a valve electromagnet 12 and vibrator 19, while the cyclone 3 is pneumatically connected to the atmosphere, and the sample in sensor 9

0 is vibrated. From the moment the valve 12 is opened, the flue gases from the flue stop and there is an intake of atmospheric air through the pipe 11, which is along the flue gas path

5 enters the ejector 7 and, together with the working gas, is discharged into the gas duct.

At the same time, under the action of the flue gas head in the duct in the tubes 1, a vacuum is created, which

0 contributes to the selection of part of the atmospheric air from the cyclone 3, which allows to clean the ash collection tubes 1 and cyclone 3 from the settled part of the ash and eliminate its burnout in the tubes 1. Distribution of atmospheric

5 air from the cyclone 3 into the flue and the ejector 7 is carried out by calculating the required cross section of the pipe 11.

From the beginning of the sampling moment in the capacitive sensor 9, a continuous measurement of the frequency of the generator 23 in the measuring unit 24 takes place, and when the generator frequency reaches the maximum value preset for these conditions, the measurement of the frequency is also stopped by the measuring unit counting device 24 determines the carbon content of the ash sample, and the result is provided by the registration unit 25 as a digital indication and / or control signal.

After allocating the maximum frequency of the generator 23, the measuring unit 24 outputs a signal to the control unit 26, which turns off the vibration compactor 19 and turns on the actuator 18 of the knee 13, as a result the compaction of the sample stops and the knee 13 with the nozzle 16 starts. vertical movement towards the sensor 9, while the lower end of the vertical part 14 of the elbow 13 enters the measuring cavity of the sensor 9 coaxially with the electrodes 20 and 21 at a predetermined speed, and the nozzle 16 - into the vertical part 6 of the gas collecting pipe 5 and sharply reduces its cross section , which reduces the vacuum in the exhaust pipe 4 and increases it in the knee 13. As a result, the flow of atmospheric air is redistributed and most of it enters through the knee 13, which helps to remove the sample from the sensor 9. Sample together with atmospheric air m to the knee 13, the pipe 16 and the gas discharge pipe 5 enters the ejector 7, and then together with the working gas in the gas duct. After the knee 13, the pipe 16 and the flange 17 have reached their extreme lower position, the control unit 26 turns off the actuator 18 and puts the vibrating compactor 19 into operation to improve the sample removal area from the capacitive sensor 9. In addition, its flange 17 is in the lower position of the pipe 16. adjacent to the inner flat surface 27 of the wall of the exhaust pipe 4 and completely covers the inlet of the vertical section 5 of the gas discharge pipe 5, which improves the conditions for complete removal of the sample from the capacitive sensor 9. After removing the sample from the capacitive encoder 9, the control unit 26 switches off and the vibrating compactor 19 includes the actuator 18, resulting in a knee 13 with the pipe 16 have their upper position by moving Referring upwards inlet gas collection pipe 5 is released from

the pipe 16 and the exhaust pipe 4 begins to perform its functions. After knee 13 leaves the capacitive sensor 9, the control unit 26 switches on the measuring unit 24 to measure the frequency of the generator 23 without the presence of a sample in the capacitive sensor, i.e. It checks the stability of the working frequency of the sensor and, if necessary, makes its correction or generates a signal for a malfunction. At a stable operating frequency, unit 24 outputs a signal to control unit 26, which turns off the electric valve valve 12, the latter closes the supply of atmospheric air to the cyclone 3 and stops the flue gas with ash from the gas duct again.

Claims (1)

Claims The system for automatically controlling the carbon content in fly ash of a coal-fired boiler unit contains ash collection tubes installed in a vertical duct and connected to a cyclone whose exhaust pipe is connected to an ejector, and the ash drain is connected to a capacitive sensor whose electrodes are included in a high generator circuit frequencies and are connected to the measuring unit and the recording unit, a sample vibration compactor, a sample level sensor, and a control unit, characterized in that. In order to improve the accuracy of control and reliability of the system, it additionally contains a pipe with a solenoid valve, connecting the cyclone to the atmosphere, and the discharge pipe of the used sample, equipped with a drive for its vertical displacements, the exhaust pipe of the cyclone is L-shaped discharge of the spent sample - in the form of a rectangular knee, fitted on the end of the horizontal part with a vertical pipe with a flange and installed inside the cyclone and the exhaust pipe with the possibility of vertical displacement, the vertical part of the knee of the discharge pipe is located coaxially with the axis of the cyclone and the capacitive sensor, the vertical pipe with flange is located coaxially with the output vertical section of the L-shaped exhaust pipe, the inner wall surface of this section of the L-shaped exhaust pipe has a horizontal flat section with which the flange contacts vertical pipe in the lower position of the latter. 2 eleven