JPH07100319A - Method for controlling cleaning of bag type reaction dust collector - Google Patents

Abstract

PURPOSE:To decrease the amt. of the neutralizing agent to be additionally added by renewing reaction layers formed in bag filters when the concn. of the treated gas in discharge air attains a set value or at a set period. CONSTITUTION:This bag type reaction dust collector 1 has the bag filters 10 for filtering the dusty air, pressure air election nozzles 13 for back washing disposed opposite to the bag filters 10 and a mechanism 30 for supplying the neutralizing agent to the treated gas during the discharge. The neutralizing agent is normally supplied at a prescribed min. ratio to the treated gas. The reaction layers sticking to the bag filters 10 are made to remain and held at the time of back washing. The operation is changed over to a back washing condition to remove the reaction layers when the concn. of the treated gas to be discharged attains the prescribed value. The reaction layers are then removed and the supply rate of the neutralizing agent is increased to rapidly regenerate the reaction layers. As a result, the amt. of the neutralizing agent to be supplied during the normal operation is minimized. Since the renewal of the reaction layers is executed during the normal operation, there is no need for stopping the operation of an incineration furnace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to dust contained in a processing gas and a toxic gas (eg, HCl) contained in the gas.
The present invention relates to a cleaning control method for a bag-type reaction dust collector that neutralizes water.

[0002]

2. Description of the Related Art Generally, exhaust gas discharged from a refuse incinerator that incinerates domestic waste contains dust and harmful gases such as HCl, NOx, SOx, etc., and therefore collects dust and treats these harmful gases. Is desired. Therefore, as one means, slaked lime is supplied in advance as a neutralizing agent to form a reaction layer on the surface of the bag filter, and then the dust-containing air generated from the incinerator is cooled, after which an appropriate amount of slaked lime (usually HCl (Equal ratio of 2 to 3 times) is continuously supplied to neutralize. Then, when a large amount of dust adheres to the bag filter and the flow resistance (pressure loss) rises above a predetermined level, backwashing conditions are selected so that the reaction layer remains, and pressure air is ejected to perform backwashing. Is taken.

[0003]

However, when used for a long period of time, there is a problem that the effective component (unreacted component) of the reaction layer is gradually reduced and the effect of the reaction layer is reduced.
On the other hand, the amount of slaked lime to be supplied together with the dust-containing air is usually increased, and the amount of slaked lime is supplied at an equivalent ratio of 4 to 5 times that of HCl. However, there is a problem that unreacted components of slaked lime are discharged together with dust by normal cleaning. In view of these points, the present invention updates the reaction layer during normal operation when the active ingredient in the reaction layer decreases and the concentration of the treated gas in the exhaust air reaches a predetermined value, and additionally supplies slaked lime. The purpose is to measure the decrease in quantity.

[0004]

A cleaning control method for a bag-type reaction dust collector according to the present invention for achieving the above object comprises a bag filter for filtering dust-containing air, and a backwash pressure air which is installed opposite to the bag filter. An injection nozzle is provided, and a supply mechanism of a neutralizing agent for the processing gas in the dust-containing air is provided on the dust-containing air supply side, a reaction layer by the neutralizing agent is formed on the surface of the bag filter, and then the neutralizing agent is added. In a bag type reaction dust collector that supplies dust-laden air while charging, and collects dust with a bag filter and neutralizes the processing gas, always supplies a predetermined minimum ratio of neutralizing agent to the processing gas, and during backwashing. Retains the reaction layer adhering to the bag filter, and when the concentration of the processing gas to be discharged reaches a predetermined value, switches to a backwash condition for removing the reaction layer,
The gist of the present invention is to remove the reaction layer and increase the supply amount of the neutralizing agent to rapidly regenerate the reaction layer.

[0005]

[Operation] When the concentration of the treated gas in the exhaust air reaches a predetermined value, the amount of the neutralizing agent supplied is increased with the complete removal of the deposits on the filtration surface of the bag filter, and the reaction layer formed by the neutralizing agent is rapidly added. Reconstruct. After that, the supply amount of the neutralizing agent is reduced to the normal supply amount, and the normal operation is started.

[0006]

[Examples] FIGS. 1 and 2 show a bag type reaction dust collector to which the present invention is applied. In this dust collector 1, the inside of the housing 2 is vertically divided by partition walls 3, the upper chamber is a purified air chamber 4, the lower chamber is a dust-containing air chamber 5, and the purified air chamber 4 is an appropriate suction fan (not shown). ) Is attached to the exhaust duct 6. The dust-containing air chamber 5 is laterally connected to a dust-containing air introduction duct 7 connected to an incinerator (not shown), and has a funnel-shaped lower portion, and a rotary valve 8 is provided at the lower end thereof.

A large number of cylindrical bottomed bag filters 10 are attached to the partition wall 3 by hanging them, and a bench lily pipe 11 is mounted by opening the upper part of the bag filters. As shown in FIG. 2, the bench lily pipes 11 are divided into a plurality of rows (four in the illustrated example) into a plurality of rows (four in the illustrated example), and the ejection tubes 12a, 12b, 12c, and 12d (hereinafter collectively referred to as “rows”) are provided for each row. In this case, the jet nozzles 13 are provided so as to face each other, the jet nozzles 13 are opened in the respective jet pipes 12, and the base ends of the bench lily pipes 12 are electromagnetic switches 14a and 14b. , 14c, 14d (hereinafter, simply referred to as 14 when collectively referred to) are connected to the air supply pipe 16 through the header 15 and the pressure air adjusted by the pressure adjusting valve 17 is connected to the electromagnetic switch 14 side. Here, the pressure adjusting valve 17 appropriately adjusts the pressure of the backwash air by a command signal described later. Reference numeral 18 denotes an intermediate duct that connects the header 15 and each electromagnetic switch 14.

Pressure detectors 20 and 21 are provided in the purified air discharge duct 6 and the dust-containing air introduction duct 7, respectively.
The output signals of both detectors are applied to the pressure loss detector 22. However, this pressure loss is a pressure loss due to the bag filter 8.
Reference numeral 23 denotes a processing gas concentration detector provided in the exhaust duct 6, and 24 denotes an air volume detector.

A neutralizer supplying mechanism 30 for the dust collector 1 is provided in the dust-containing air introduction duct 8 as close to the dust collector 1 as possible. The supply mechanism 30 includes a neutralizer storage tank 31, a delivery mechanism drive motor 32 for delivering the neutralizer in the storage tank, and a rotation speed control unit 33 and an input unit 34 of the drive motor. Reference numeral 35 represents a charging pressure air supply pipe. When the induction motor is used as the drive motor, the rotation speed control unit 33 has a pole number conversion method, a frequency conversion method, or the like. However, the number of rotations of the motor is variable and is always low, and the speed can be changed so as to supply a predetermined amount (usually 2 to 3 equivalent ratio) of the neutralizing agent to the concentration of the processing gas in the dust-containing air that is sent out. After the reaction layer of the bag filter 10 to be described later is removed, the motor 32 is rotated at a high speed to increase the supply amount, and the amount necessary to regenerate the reaction layer is fed to the bag filter.

Reference numeral 40 designates the pressure regulating valve 17 and the electromagnetic switch 1.
4 and a cleaning control mechanism for controlling the rotation speed control unit 33 of the neutralizing agent supply mechanism 30 to control the strength of backwashing, the interval, and the supply of the neutralizing agent to the bag filter 10. The control procedure is shown below. It will be described based on 3.

The figure shows the relationship between the pressure loss, the supply amount of the neutralizing agent and the concentration of the processing gas on the discharge side, where A is the pressure loss value, B is the supply amount of the neutralizing agent, and C is the concentration of the processing gas in the exhaust gas. . First, at the start of operation D, the pressure of the backwash air is set to a low pressure by the pressure control valve 17, the backwash interval is lengthened, and the backwash of the bag filter 10 is made as small as possible. At the same time, the rotation speed control unit 33 of the neutralizing agent supply mechanism 30 is set to the high speed operation side, and a large amount Q of the neutralizing agent (for example, about 10 times the additional addition amount in the normal operation) is supplied. As a result, a reaction layer having a required thickness is formed on the bag filter 10. After reaching the point E at the end of the reaction layer formation, the rotation speed control unit 33 switches the drive motor 32 to the low speed operation side and automatically adjusts the backwash pressure and the backwash interval to keep the pressure loss value P of the bag filter 10. . During this normal operation, the neutralizing agent supply mechanism 30 regulates the rotation speed of the drive motor 32 according to the change in the processing gas concentration detected by the processing gas concentration detector 23 provided in the exhaust duct 6, and is proportional to the processing gas concentration. Equivalent ratio (eg 2-3
Add a neutralizing agent in an amount of (equivalent ratio).

Thereafter, along with the normal operation, a predetermined amount of the neutralizing agent is supplied together with the processing gas by the neutralizing agent supplying mechanism 30 and accumulated in the bag filter 10. This adhesion amount is detected as a pressure loss by the pressure loss detector 22. It should be noted that the control circuit 40 performs cleaning for removing the adhering dust (referred to as normal cleaning).

In this case, when the bag filter 10 is back-washed by each jet pipe 12, it is necessary to leave the reaction layer. That is, it is necessary to set a predetermined pressure loss value P. Therefore, the backwash pressure and the backwash interval are automatically adjusted by the measured pressure loss value and the measured air flow rate value.

The concentration of the processing gas (HCl) in the exhaust gas of the exhaust duct 6 after completion of the cleaning is a constant equivalent ratio (for example, 2 to 3 equivalent ratio) of the amount of the neutralizing agent to the concentration of the processing gas.
However, this does not completely neutralize, the neutralizing agent in the reaction layer reacts, and the reaction components (unreacted components) decrease with the passage of time. Therefore, when the HCl concentration in the exhaust air gradually rises and finally reaches the predetermined concentration R or when it is determined by the time setting, the control mechanism 40 detects this and backwashing for renewal to remove even the reaction layer ( It is called forced cleaning). Let F be that point.

In this case, in response to a command from the cleaning control mechanism 40, the pressure air for backwashing is increased to a high pressure by the pressure adjusting valve 17, and the electromagnetic switches 14a to 14d are sequentially operated.
Simultaneously with the backwashing with high-pressure air, the control mechanism 40 switches the rotation speed control unit 33 of the neutralizing agent supply mechanism 30 to the high speed side, and the maximum amount Q of the neutralizing agent (for example, an equivalence ratio of about 10 times to HCl of the processing gas). ) To.

The point G is the end of the backwash. After that, a large amount of the neutralizing agent is continued and the backwash is stopped to form a reaction layer, and when the reaction layer reaches a predetermined thickness (point H), the large amount of the neutralizing agent is stopped. Then, the rotation speed control unit 33 switches the drive motor 32 to the low speed operation side.
After that, this process is repeated, and the processing gas concentration is the concentration R as described above.
At point I at which the temperature reaches 1, the reaction layer is renewed by strong backwashing (forced cleaning) as described above.

[0017]

As described above, according to the present invention, the reaction layer formed on the bag filter is renewed when the concentration of the processing gas in the exhaust air reaches the set value or at the set period, so that the normal operation is not performed. Even if the supply amount of the neutralizing agent is small (for example, 2 to 3 equivalent ratio) with respect to the processing gas concentration, it is possible to reduce operation delay and reaction leakage when the amount of generated HCl is large, and to perform stable processing. The supply amount of the neutralizing agent can be reduced. Further, since this updating is performed during the normal operation, it can be performed without stopping the operation of the incinerator that continuously operates, such as the refuse incinerator.

[Brief description of drawings]

FIG. 1 is an overall explanatory view of a dust collector according to the present invention.

FIG. 2 is a sectional view taken along line XX in FIG.

FIG. 3 is an explanatory diagram of a cleaning control procedure of the present invention.

[Explanation of symbols]

 1 bag type reaction dust collector 10 bag filter 13 pressure air jet nozzle 30 neutralizer injection mechanism 40 cleaning control mechanism

Claims (1)

[Claims] 1. A bag filter for filtering dust-containing air,
A backwashing pressure air jet nozzle is provided opposite to the bag filter, and a supply mechanism for supplying a neutralizing agent to the processing gas in the dust-containing air is provided on the dust-containing air supply side. In a bag type reaction dust collector that forms on the surface of a bag filter and then supplies dust-containing air while charging the neutralizing agent, the bag filter collects dust and neutralizes the processed gas. A ratio of the neutralizing agent is supplied, and the reaction layer adhering to the bag filter is retained and retained during backwashing, and when the concentration of the processing gas to be discharged reaches a predetermined value, the backwashing condition for removing the reaction layer is switched to A cleaning control method for a bag-type reaction dust collector, characterized in that the reaction layer is removed and the supply amount of the neutralizing agent is increased to regenerate the reaction layer rapidly.