JPH056524Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dust concentration detection device for detecting the amount of dust in a flue, and more particularly to a mechanism for automatically purging dirt adhering to the dust concentration detection device.

Generally, in electrostatic precipitators (hereinafter referred to as EP), in order to operate the EP efficiently, the EP charging voltage and current are adjusted so that the amount of soot and dust at the EP outlet is within a certain range below the specified value. . Here, the amount of soot and dust at the EP outlet is detected by a soot and dust concentration detection device.

FIG. 1 is a diagram showing the configuration of a conventional dust concentration detection device. The dust concentration detection device 1 includes a sampling tube 2, manual valves 3a, 3b, a light source section 4, and a light receiving section 5. When detecting soot from the dust-containing gas G flowing through the flue E at the EP outlet, a part of the dust-containing gas G is sampled from the dynamic pressure port 6 of the sampling pipe 2 protruding into the flue E. . The sampled gas G is discharged into the flue E again from the static pressure port 7 of the sampling tube 2 via the manual valves 3a and 3b. At this time, the manual valves 3a and 3b
The light emitted from the lamp 8 of the light source section 4 is transmitted through the gas G via the lens 9, and the transmitted light is received by the light receiving element 11 via the lens 10 of the light receiving section 5. This allows detection of soot and dust concentration.

However, in the conventional dust concentration detection device 1 described above, when detecting a relatively large amount of dust, errors may occur in the measured value due to "clogging" caused by dust adhering to the inner surface of the sampling tube 2. Further, there is a possibility that errors may occur due to dirt on the optical system such as the light source section 4 and the light receiving section 5.

FIG. 2 is a diagram showing output changes due to dust adhesion within the sampling pipe 2 of the dust concentration detection device 1 in relation to measurement time. The solid line L in the figure shows the case where the soot and dust concentration is 10 mg/m ³ N, and the broken line M in the figure shows the case where the soot and dust concentration is 400 mg/m ³ N. As is clear from the figure, when the dust concentration is 10 mg/m ³ N, the output of the dust concentration detection device 1 decreases by approximately 2% after 4 days from the start of measurement, and by approximately 18% after 6 days. . In addition, when the soot dust concentration is 400 mg/m ³ N, it is approximately 4
It has been confirmed that the output decreases to several percent within days.

In order to prevent such a decrease in output, conventionally A1, A2, A3, etc. in Fig. 2 were set at time points, that is, from 2 days to
It was necessary to air purge the sampling tube 2 once every four days. Also, it is necessary to calibrate the optical system against dirt approximately once every two weeks.
Cleaning was carried out by blowing air from an airline (not shown) or by removing caps, etc.

The purpose of this invention is to automatically purge air at regular intervals to detect soot and dust concentration, thereby prolonging the maintenance period while preventing dirt on the sampling tube and optical system from adversely affecting the optical system due to re-scattering of dust. The goal is to provide equipment.

In order to achieve the above object, the present invention is characterized by the following structure. That is, in a dust concentration detection device that samples dust-containing gas in a flue using a sampling tube, and detects the concentration of dust contained in the sampled dust-containing gas by an optical system consisting of a light source section and a light receiving section, the above-mentioned A plurality of purge nozzles provided in the optical system and the sampling tube, a plurality of air supply pipes provided to respectively supply purge air to the plurality of purge nozzles, and among these air supply pipes, a first valve provided in an air supply pipe connected to the sampling pipe purge nozzle to adjust the amount of purge air supplied; and an air supply pipe connected to the optical system purge nozzle in the air supply pipe. A continuous purge air piping section attached to the supply pipe and provided to constantly continuously supply a predetermined amount of purge air to the optical system through the air supply pipe, and a continuous purge air piping section parallel to the continuous purge air piping section. A periodic purge air piping section connected to the optical system for periodically supplying purge air to the optical system, and a periodic purge air piping section provided to adjust the amount of purge air supplied to the periodic purge air piping section. a second valve; and automatic control means that automatically controls supply of purge air at a predetermined period and for a set time via the first valve and the second valve, The air purge to the tube is started after the amount of purge air supplied to the optical system is increased from the normal value supplied through the continuous purge air piping section, and the amount of air supplied to the optical system is increased. It is characterized in that it is configured to be stopped before returning to the normal value.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a diagram showing the structure of the dust concentration detector 21 in an embodiment of the present invention. Note that the first
Components common to those in the figures are given the same reference numerals and detailed explanations will be omitted. Sampling tube 2 of dust concentration detector 21
An electric valve 22 is provided in the intake pipe 2a. The dust concentration detector 21 also includes a nozzle 31 for purging the light source section 4, a nozzle 32 for purging the light receiving section 5, and a nozzle 3 for purging the exhaust pipe 2b and the static pressure port 7 of the sampling pipe 2.
3 and a nozzle 34 for purging the dynamic pressure port 6 of the sampling tube 2.
34 is connected to an air supply pipe of an automatic purge mechanism 35 as shown in FIG.

FIG. 4 is a diagram showing the dust concentration detector 21 and an automatic purge mechanism 35 that automatically purges the detector 21. In the figure, 40 is an air supply pipe that supplies air H from the outside, and this air supply pipe 40 is branched into four systems of air supply pipes 41, 42, 43, and 44 through a main valve 50, and is connected to each of the nozzles 31 to 44. Air H is supplied to 34.

First air supply pipe 41 for purging the light source section 4
is in communication with the nozzle 31 via a solenoid valve 51, a manual valve 52, and a flow rate indicator 53. Also, the light receiving section 5
The second air supply pipe 42 for purging the solenoid valve 6
1. It communicates with the nozzle 32 via a manual valve 62 and a flow rate indicator 63. Note that the optical system consisting of the light source section 4 and the light receiving section 5 is connected to the first and second air supply pipes 41 and 42 so that it can be purged with a small amount of air at all times without using the automatic purge mechanism 35.
Branch pipes 55, 65 equipped with manual valves 54, 64
is provided, and the amount of air is adjusted by the manual valves 54, 64.

Static pressure port 7 of exhaust pipe 2b and sampling pipe 2
The third air supply pipe 43 for purging is connected to the manual valve 7.
2. It communicates with the nozzle 33 via a flow rate indicator 73 and a solenoid valve 71. Further, the fourth air supply pipe 44 for purging the dynamic pressure port 6 of the sampling pipe 2 communicates with the nozzle 34 via a manual valve 82, a flow rate indicator 83, and a solenoid valve 81.

The manual valves 52, 62, 72, and 82 determine the maximum amount of air during automatic purging, and the solenoid valves 51, 61, 71, and 81 are only opened and closed under the control of the automatic purge control circuit 90. In addition, the above flow rate indicators 53, 63, 73, 83
measures the air flow rate during automatic purging, detects a decrease in flow rate or increase in pressure due to "clogging" of each of the air supply pipes 41 to 44, and sends an abnormal signal to the automatic purge control circuit 90. . This improves reliability.

The automatic purge control circuit 90 controls the electric valve 2 by controlling signals S1, S2, and S3 based on an automatic purge signal S having a predetermined period, for example, a period of 6 to 24 hours.
2. Control the solenoid valves 51, 61 and 71, 81. Further, the control circuit 90 is connected to the soot and dust concentration detector 21.
Abnormality information SX based on abnormality signals from the flow rate indicators 53 to 83 and information SY indicating that automatic purging is in progress are output to an automatic EP performance control device (not shown).

Next, the operation of the automatic purge mechanism in the apparatus thus constructed will be explained with reference to the time chart shown in FIG.

Normally, the manual valves 54 and 64 of the first air supply pipe 41 and the second air supply pipe 42 are slightly opened.
The optical system consisting of the light source section 4 and the light receiving section 5 is purged with a small amount of air. In this state, the automatic purge control circuit 90 outputs control signals S1 to S3 based on the automatic purge signal S. The automatic purge signal S has a predetermined period T (for example, a period of 6 to 24 hours)
This is an electrical signal output from the dust concentration detector 2.
It has the width required for one purge. Note that the set period of 6 to 24 hours is within a range that is not affected by the changes over time shown in FIG.

When the control signal S1 based on the automatic purge signal S is output, the electric valve 22 on the inlet side of the dust concentration detector 21 is closed. At approximately the same time, the solenoid valves 51 and 61 are opened by the control signal S2. This increases the air flow rate of the first air supply pipe 41 and the second air supply pipe 42, and prevents the optical system from being adversely affected by dust re-scattering during purging. Next, the control signal S3 opens the solenoid valve 71 for purging the exhaust pipe 2b, etc., and the solenoid valve 81 for purging the dynamic pressure port 6, and the nozzles 33, 34 are opened.
Powerful air is supplied to each, and purge is performed in a short time. The increase in the air flow rate to the optical system by the electromagnetic valves 51 and 61 continues until the influence of the scattered dust disappears. And the automatic purge signal S
When turned off, the control signals S1 and S2 are cut off, thereby closing the solenoid valves 51 and 61. At the same time, the electric valve 22 opens and returns to its original state. In this way, the soot and dust concentration is measured again.

As explained above, the present invention is characterized by the following configuration.

That is, the dust concentration is such that the dust-containing gas in the flue E is sampled by the sampling tube 2, and the concentration of the dust contained in the sampled dust-containing gas is detected by an optical system consisting of the light source section 4 and the light receiving section 5. In the detection device, there are a plurality of purge nozzles 31 to 34 provided in the optical systems 4 and 5 and the sampling tube 2, and a plurality of purge nozzles 31 to 34 provided to supply purge air to the plurality of purge nozzles 31 to 34, respectively. air supply pipes 41 to 44, and these air supply pipes 41 to 4.
4, the sampling tube purge nozzle 3
first valves 71, 72 and 81, 82 provided in the air supply pipes 43, 44 connected to the first valves 3, 34, respectively, so as to adjust the amount of purge air supplied;
Among the air supply pipes 41 to 44, the air supply pipe 4 is connected to the optical system purge nozzles 31 and 32.
A continuous purge air piping section (valve 54 and 64) is attached to the air supply pipes 41 and 42 and is provided to continuously supply a predetermined amount of purge air to the optical systems 4 and 5 through the air supply pipes 41 and 42. branch pipes 55 and 65), respectively, and continuous purge air piping sections 55 and 65, respectively, are connected in parallel to each other and periodically supply purge air to the optical systems 4 and 5 at regular intervals. Purge air piping section (piping section equipped with valves 51, 52 and valves 61, 6)
2), and second valves 51, 52 and 61, 62 provided in this periodic purge air piping section to adjust the amount of purge air supplied.
and automatic control means (automatic purge control circuit 90 and valves 71, 81 and valves 51, 61
The air purge to the sampling tube 2 is performed by increasing the amount of purge air supplied to the optical systems 4 and 5 from the normal value supplied through the continuous purge air piping sections 55 and 65. It is characterized in that it is configured such that it is started after the amount of air supplied to the optical systems 4 and 5 returns to the normal value.

Therefore, according to the present invention, the following effects can be expected.

(a) A predetermined amount of purge air is always continuously supplied to the optical systems 4 and 5 by the continuous purge air piping sections 55 and 65. Therefore, the optical systems 4 and 5 are constantly subjected to air purging. Then, when the automatic control means 90 or the like starts a periodic air purge operation, the air piping section for periodic purge, which is additionally attached in parallel to the continuous purge air piping sections 55 and 65, is started. Purge air is temporarily supplied to the optical systems 4 and 5 for a preset period of time. This purge air is supplied in a state where it is superimposed and merged with the steady state purge air that is constantly and continuously supplied. Therefore, the optical systems 4 and 5 are strongly air purged.

(b) On the other hand, air purge to sampling tube 2 is as follows:
This is performed in synchronization with the air purge to the optical systems 4 and 5. This air purge to the sampling tube 2 is quite powerful. Therefore, a large amount of dust is re-splattered by air purging to the sampling tube 2. However, the air purge to the sampling tube is carried out during the period (w) during which the air purge to the optical systems 4 and 5 is performed.
It is carried out within a relatively short and specific time within the period (w). Therefore, even if the re-scattered dust tries to re-attach to the optical systems 4 and 5, strong air purge is continuously performed on the optical systems 4 and 5, so that the re-scattered dust will not adhere to the optical systems 4 and 5. There is no possibility that the optical systems 4 and 5 will be adversely affected.

(c) As a result of the above, while preventing the adverse effects on the optical systems 4 and 5 due to dust re-scattering during air purge, the sampling tube 2 and the optical systems 4 and 5 are cleaned periodically, that is, for a predetermined period of time. At intervals, air purge can be performed automatically. In this way, it is possible to provide a soot and dust concentration detection device that can extend the maintenance period.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams for explaining the conventional example, with Figure 1 showing the configuration, Figure 2 showing the output change due to dust adhesion in the sampling tube in relation to measurement time, Figures 3 to 5 are diagrams for explaining one embodiment of the present invention. Figure 3 is a diagram showing the configuration of a dust concentration detector, and Figure 4 is an automatic purge mechanism connected to the dust concentration detector. FIG. 5 is a diagram showing the timing of opening and closing of each valve. 2...Sampling tube, 3a, 3b...Manual valve, 4...Light source section, 5...Light receiving section, 21...Soot dust concentration detector, 22...Electric valve, 31-34
... Nozzle, 41-44 ... Air supply pipe, 51,
61, 71, 81... Solenoid valve, 52, 54, 6
2, 64, 72, 82...manual valve, 53, 63,
73, 83...Flow rate indicator, 90...Automatic purge control circuit.

Claims (1)

[Scope of claim for utility model registration] A sampling tube that samples dust-containing gas in a flue, a light source unit that irradiates light to the dust-containing gas sampled by the sampling tube, and the light source unit that transmits light through the dust-containing gas. an optical system consisting of a light receiving section that receives the light of the light and detects the dust concentration;
A plurality of purge nozzles provided in the optical system and the sampling tube, a plurality of air supply pipes provided to supply purge air to each of the plurality of purge nozzles, and A first valve is provided to adjust the amount of purge air supplied to an air supply pipe connected to the sampling pipe purge nozzle, and a first valve is connected to the optical system purge nozzle of the air supply pipe. a continuous purge air piping section attached to the air supply pipe so as to constantly supply a predetermined amount of purge air to the optical system through the air supply pipe; a periodic purge air piping section connected in parallel for periodically supplying purge air to the optical system;
a second valve provided in the periodic purge air piping section to adjust the amount of purge air supplied;
automatic control means for automatically controlling the supply of purge air through the first valve and the second valve at a predetermined period and for a set time; Started after the amount of purge air supplied to the optical system increases above the normal value supplied through the continuous purge air piping section, and before the amount of air supplied to the optical system returns to the normal value. A soot and dust concentration detection device, characterized in that it is configured to be stopped.