RU1802258C - Method of check of slagging of steam bolter heating surface - Google Patents

Abstract

Usage: heat power engineering and can be used to control slagging of boiler heating surfaces. SUMMARY OF THE INVENTION: After a measuring transducer 6, a unified current signal is fed to the input of a differentiator 8. In a differentiator 8, a constant component is filtered out of the rarefaction signal to avoid the influence of low-frequency pulsation of the rarefaction. The differentiated signal is rectified by the device 9 and fed to the input of the alarm device 10. When the input signal reaches the minimum predetermined value, the alarm device 10 is activated and notifies the operator of the increase in slag deposits. 4 ill.

Description

Figl

The invention relates to a power system and can be used to control the operation of a boiler unit, namely, slagging of heating surfaces.

The aim of the invention is to simplify control and increase its reliability.

In FIG. 1 shows a diagram of a device that implements the proposed method; in FIG. 2 is a timing chart for measuring the amplitude of rarefaction pulsations. no contamination of the heating surface by slag deposits; Fig. 3 is a connection diagram of a rectifier device; Fig. 4 is a view of a diagram tape obtained as a result of testing at a boiler unit TP-230 of Tomsk State District Power Station-2 during the burning of Cheremkhov coal.

The device for controlling the slagging of the heating surfaces of the steam boiler contains a hollow probe 1 attached by welding to one of the pipes 2 on the evaporative heating surface, where slag deposits are formed 3. The cavity of the working element of the probe T is connected by a steel pipe 4 through a locking device 5 to the measuring a transducer 6, the output of which is connected to the input of block 7. Block 7 contains a series-connected differentiator 8, a rectifier device 9 and an alarm device 10. Probe 1 through a shut-off the building 11 is also connected to the pipe 12.

 The control device operates as follows.

In control mode, the locking device 11 is closed, and 5 is open. The vacuum generated in the furnace during the flue gas exhaust during combustion is transmitted through the working element of the probe 1 and pipe 4 to the working chamber of the measuring transducer b, which converts the rarefaction signal into a unified current signal of 0-5 mA. A view of the resulting current signal is shown in FIG. 2. The pulsations of the signal are determined by the nature of the operation of the boiler unit, for example, dust collectors supply coal dust to the furnace of the boiler unit not continuously, but in portions and accordingly affect the fluctuation of the vacuum in the furnace. In addition, the type and condition of the exhaust fan blades affects the variation in vacuum, since they also capture the flue gas in portions. All this, as well as the dynamic properties of the furnace and gas ducts of the boiler unit, have an effect on the type of signal in vacuum. From the graph (see Fig. 2) it is seen that as deposits on the surface, heat, respectively, on the working element of the probe,

the amplitude of rarefaction pulsations decreases.

The dependence of the amplitude of the signal in the vacuum recorded by the measuring

converter b, the degree of slag can be traced by the following example. Consider the amplitude-frequency characteristic (AFC) of the furnace - hollow probe - measuring chamber

converter. This frequency response A (j w), with a transfer coefficient K, is described by the following equation:

fifteen

AQco) K / Vi + u / h

Let us trace the dependence of the amplitude of rarefaction pulsations in the working chamber of the measuring transducer at a constant frequency, i.e. w const, from the constant time T. T characterizes the inertia in the transmission of the signal by vacuum through the hollow probe 1 into the working chamber of the measuring transducer 6. At T 0, i.e. when the probe element is clean and does not create

no resistance, the amplitude of rarefaction pulsations will have its greatest value A (j co) K. With an increase in the number of slag deposits on the working element of the probe, resistance arises, thereby

the time constant T increases. With increasing T, the amplitude of the rarefaction pulsations will decrease, which is clearly seen from the frequency response formula A (j a)} K. And finally, when T -, the amplitude of the rarefaction pulsations

will tend to zero AQ o). Thus, the amplitude of rarefaction pulsations measured by the measuring transducer b is directly dependent on the degree of slagging of the heating surfaces

boiler unit.

After the measuring transducer 6, a unified current signal is fed to the input of block 7, i.e. to a differentiator 8, which is designed to filter out a constant component from the rarefaction signal to avoid any low-frequency pulsation of the rarefaction.

Further differentiated signal

it is rectified by the device 9 and arrives at the input of the alarm device 10, which is a device for comparing the level of the input signal with the value set by the setpoint potentiometer.

When the input signal reaches the level of the minimum pre-set value, the alarm device 10 is activated and notifies the operator of an increase on the heating surface. and accordingly, on the working element of the probe 1, a large number of slag deposits. After the alarm device is triggered, the surfaces of the heater are cleaned using standard means. After cleaning, in order to set the Control device to its initial position, the stop device 11 is opened, and the shut-off device (JTBO 5 is closed and iodine 12 supplies pressure gas or steam to the working element of probe 1, thereby knocking slag deposits around the inlet holes.

As a signal transducer for rarefaction into an electric signal, d) a measuring transducer of the Sapphire-22DIV type was used. As unit 7, a conductive separation unit with a two-limit signaling of the BKRZ-P type was used, tuned to differentiate the input signal and to signal when this signal reaches the lower level. But the BKRZ-P unit is used with a slight refinement (see Fig. 3) in HJsro a rectifier device is built-in. 91 The numbers 28 and 15 show the terminal numbers to which this device is connected. 9 The rectifier device 9 is the simplest rectifier. taken on diode 13 and capacitor 14, which acts as a smoothing filter. A diode of type D223 was used as a diode, and a capacitor of type K50-6 500 uF x 10V was used as a capacitor.

The proposed method has been tested on; TP-230 boiler unit station No. 7 of Tomsk State District Power Station-2. The hollow probe 1 (see Fig. 1) is made of corrosion resistant steel 20 x 13 GOST 5632-72 and is attached to one of the pipes of the heating surface by welding. The working element of the hollow probe is connected using a steel pipe 4, with the working chamber of the measuring transformer Sapphire-22 DIV 6, which is designed to measure the vacuum within 0-0.25 kPA. The measuring transducer 6 was placed on a block control panel (BSC). Unit 6KR-ZP (7) with integrated rectifier 9 is also located on the control room.

The tests were started at 3.20 p.m. on March 27, 1989. The results were recorded using a KSU-2 self-recording secondary transducer, which recorded the signal coming from measuring transducer b, thereby registering the dependence of the amplitude of rarefaction pulsations on the degree of slagging of the heating surface. At the beginning of operation, the amplitude of the signal along the rarefaction was b mm water. Art. (see Fig. 4), at 0 hours 14 minutes on March 29, 1989 the signal amplitude was already 4 mm water column. (see Fig. 4), that 5 indicates the growth of a certain amount of slag deposits on the heating surface. By 4 hours and 40 minutes on April 1, 1989, the signal amplitude in the vacuum was 2 mm water column. By 16 h 37 min 3 april

The 1989 amplitude was 1 mm water column. By 1915 hours on April 5, 1989, the amplitude of rarefaction pulsations became less than a predetermined level, i.e. 0.5 mm water column, which corresponds to an increase in the working

5 probe element, and, accordingly, on the heating surface, a large number of slag deposits, in connection with which the light alarm went off at the BKR-ZP block (block 7, see Fig. 1) and surface cleaning agents were included in the operation of the boiler heating up. A view of the chart tape is shown in FIG. 4.

Using the proposed method for controlling slagging of the heating surfaces of a steam boiler provides the following advantages in comparison with the prototype.

The method does not require the creation of complex technical devices, and additional

0. equipment (smoke exhausters, special gas paths, etc.), is easy to implement, because uses standard equipment.

When using the proposed method, there are no additional suction cups in the boiler flue and there is no need to install a flow regulator, which, as a rule, operates in a narrow range of pressure drops. These conditions simplify

Claims (1)

0 the implementation of the proposed method and increase the reliability of control. SUMMARY OF THE INVENTION A method for controlling slagging of a heating surface of a steam boiler by measuring a signal characterizing the amount of ash deposits deposited on a working element of a probe placed on one of the pipes of the heating surface in a gas stream under investigation, characterized 0 by the fact that, in order to simplify and increase the reliability of control, using the working element of the probe, the rarefaction signal in the boiler furnace is measured, the rarefaction signal is converted into an electric signal, the constant component is filtered out5, and as a signal characterizing the amount of ash deposits deposited on the working element of the probe uses the amplitude of rarefaction pulsations. (jpus.4