JPS6054747A - Electric precipitator - Google Patents

Abstract

PURPOSE:To improve an electric precipitator in saving power consumption and reliability by determining the dust concn. at the outlet of the precipitator exactly and controlling the amt. of electric charge properly. CONSTITUTION:A detector 2 for the amt. of treated gas and a detector 4 for the inlet dust concn. are provided between the dust source and an electric precipitator 5 and plural numbers of detectors 6 for outlet dust concn. are provided to the outlet side of the electrostatic precipitator 5. The dust concn. at the outlet side is calculated from detected values of the detector 2 for the amt. of treated gas and the detector 4 for the inlet dust concn. etc. using relational equations between the outlet dust concn. and treated gas amt., and inlet dust concn., etc. A controlling device 9 for electric charge operates comparation of the calculated value for the outlet dust concn. and plural detected values from outlet dust concn. detectors 6, and sets proper outlet dust concn. The electric charge of the electric precipitator 5 is controlled by using the set value.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrostatic precipitator, and the present invention relates to an electrostatic precipitator that is equipped with a control device that controls the amount of charge depending on the dust concentration at the outlet of the electrostatic precipitator. Regarding equipment.

[Background of the invention]

This type of electrostatic precipitator consists of an electrostatic precipitator consisting of a dust collecting plate and a discharge wire, and a DC high-voltage power supply that supplies high voltage to the discharge wire, and removes dust from exhaust gas from dust sources such as boilers. It is like that.

Suke 1. In such equipment, the dust collection performance is high.
In general, the applied voltage is controlled to be high and the discharge current is controlled to be large within a range where performance does not deteriorate due to sparks, reverse ionization, etc.

However, such a control method cannot be used when the amount of processing gas is small or when the inlet dust concentration is low.

There was a tendency for the dust collection performance to increase more than necessary. For this reason, from the perspective of power saving, control has begun to be implemented in such cases by reducing the amount of charge in the electrostatic precipitator to save power within a range that does not exceed the required dust concentration in the outlet gas. . As a control method in this case, on the outlet side of the electrostatic precipitator,
Installing a dust concentration meter and performing feedback control by comparing the dust concentration with a target value can be easily devised by analogy with the control of other devices. However, with this method, there are problems such as the reliability of the indicated value when the dust concentration meter is used for a long time, and the current situation is that sufficient control has not yet been performed.

[Purpose of the invention]

This invention was proposed in view of the above circumstances, and its purpose is to more accurately determine the dust concentration at the outlet of an electrostatic precipitator and to save power by appropriately controlling the amount of charge. Our goal is to provide highly reliable electrostatic precipitators.

[Number of inventions]

In this invention, the outlet dust concentration is determined by the inlet dust concentration, processing gas amount, charging voltage, and current of the electrostatic precipitator.
It has been experimentally confirmed that there is a certain relationship within a certain accuracy range.

■ Store this relational calculation formula in the control calculation section.

(2) Calculate the outlet dust concentration (having a certain width) from the processing gas amount, inlet dust concentration, charging voltage, and current using this relational expression.

(2) A plurality of outlet dust concentration detection values from multiple detectors arranged on the outlet side of the electrostatic precipitator are compared with the outlet dust concentration calculation value (2), and an appropriate outlet dust concentration is set.

Here, as a setting method, when each detected value is within the accuracy range of the calculated value, the average value of the detected values is set as the true value and 17. If at least one of the detected values is outside the accuracy range, the average value excluding that value is considered the true value, and if all detected values are outside the accuracy range, the calculated value is used as the true value. There is a way to do it.

■ Control the amount of charge based on the set value of the exit dust concentration.

The present invention is configured to perform two or more types of control.

〔Example〕

The present invention will be described below based on an illustrated embodiment. As shown in FIG.

This is the case of a steam generation boiler 1, in which a venturi flowmeter 2. A light transmission type dust concentration meter 4 for measuring the inlet dust concentration Ci is provided, and two light transmission type dust concentration meters 6 are also installed on the exit side of the dust collector 5.

The light transmission type dust densitometer uses a Ji glass plate in the optical path.

The biggest problem is the occurrence of measurement errors over time due to the fluctuation of the zero point of the dust concentration due to dirt on the lens, etc. The influence is particularly large on the low concentration side, such as at the exit of the dust collector. For this reason, we experimented with measures to prevent contamination, such as sealing with clean air, but these were not sufficient. Therefore, it was decided to arrange two concentration meters 6 side by side along the gas flow path. It was better to keep the distances as close as possible so that the light scattered by the dust would not affect the calculated value of the neighboring mycelium concentration.

In such a configuration, the detection signals of the detectors 2, 4.6, the voltage V of the high-voltage power supply 8, and the lightning current.

It is input to the charge amount control device 9. In addition, in FIG. 1, 3 is a flow rate converter, and 7 is an exhaust fan.

The control device 9 has a built-in microcomputer,
The arithmetic processing shown in the flowchart of FIG. 2 is performed.

This flowchart can be roughly divided into three steps r and n.
, m.

Step E〉 Found experimentally. Exit dust concentration CO and gas amount Q, inlet dust m degree C number, charging voltage V.

Using the relational expression with the discharge current ■, Q, Ci, V,
The part where the calculated value CO of the exit dust concentration is calculated by substituting the measured value of I.

(Step 2) A part where the actual exit dust concentration values C1 and C2 obtained from the 61 degree G resistance are compared with the above-mentioned calculated value Co to estimate the most appropriate exit dust concentration a degree.

Step ■■> From this set value of outlet dust concentration, charge voltage V required to bring the outlet dust concentration to the target value.

Calculate the discharge current and adjust this voltage and current.

And the part that corrects the coefficients of the relational expression used in step ■.

Here, the following equation was used as the above-mentioned relational equation.

c, -J(ci)-f(v)-f(vT)z#((2-
=- (1) In this equation, the form of each function and its coefficients were determined experimentally. The range in which the coefficient changes was also determined through experiments. This makes it possible to clarify the range in which the exit dust concentration changes at certain values of gas amount, inlet dust, charging voltage, and discharge current. Therefore, the exit dust concentration C in step I.

is a calculated value with a certain range of variation.

The dust concentration signals Cx and C2 from the two dust concentration meters 6 should show almost the same values, and the difference in the indicated values often mainly indicates the progress of dirt on the concentration meters. .

In this embodiment, the indicated value C1, Ca of 11 degree G resistance is compared with the calculated value Co.

First, if C1 and 02 are within the range of CO, C1°C
The least square mean value of the median values of 2 and Co was considered as the exit dust concentration.

If there was a difference between C1 and C2 and one of them was outside the range of Co, that indicated value was excluded and the average value of the remaining indicated values and the median value of Co was considered as the exit dust concentration. Also,
In this case, a cautionary comment is output.

When both C1 and C2 were outside the range of co, one median value of co was regarded as the exit dust concentration. At this time as well, a cautionary comment regarding the operation of the densitometer is issued.

The voltage and current are adjusted by calculating the amount of charge q required to reach the set value based on the set value of the exit dust concentration and comparing it with the current amount of charge q'. Additionally, in accordance with this, the coefficients of equation (1) are corrected.

In this way, the exit dust concentration is measured using two detectors,
In addition, since the calculation is performed in comparison with the calculated value calculated using the empirical formula, the exit dust concentration can be determined more accurately. by this.

It is possible to control the exit dust concentration and reduce the tolerance.
It has become possible to perform highly reliable control with a small amount of charge.

In the above embodiment, the inlet dust concentration is measured, but it may be omitted in cases where the dust concentration does not vary significantly depending on the load, such as in a pulverized coal boiler, or it may be measured based on the pulverized coal supply amount. It may be calculated. The exit dust concentration may be measured by other measurement methods such as the β-ray absorption method, and any detection signal may be used as long as it is a related signal E.

〔Effect of the invention〕

According to the present invention, the dust concentration at the exit of the electrostatic precipitator can be set more accurately, and the amount of charge can thereby be appropriately controlled, and the electrostatic precipitator is energy-saving and highly reliable. It can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a flowchart of the program of the control device. 1... Boiler 2... Flow meter 3... Flow rate converter 4... Inlet dust concentration meter 5...
- Electrostatic precipitator 6... Exit dust concentration meter 7... Exhaust fan 8... High voltage power supply 9... Charge amount control device.

Claims (1)

[Claims] (1) A processing gas amount detector and an inlet dust concentration detector are installed between the dust generation source and the electrostatic precipitator, and multiple outlet dust concentration detectors are placed on the outlet side of the electrostatic precipitator. Using the relational expression between the concentration, the amount of processed gas, the inlet dust concentration, etc., the outlet dust concentration is calculated from the detected values of the processed gas amount detector, the entrance rodass 1 degree detector, etc., and the calculated value of the outlet dust concentration is calculated. , comprising a control device that compares and calculates a plurality of detected values from the outlet dust concentration detector to set an appropriate outlet dust concentration, and uses this set value to control the amount of charge of the electrostatic precipitator. An electrostatic precipitator characterized by: