JP2002045727A - Operation method for electric dust collector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operation method for an electric dust collector whereby the problems caused by the combustion of oily components and carbon in dust are solved and the decrease in dust collection efficiency can be prevented even when the percentage of added quick lime is increased. SOLUTION: This operation method is characterized in that in doing uncharged continuous hammering at regular intervals, a charged section is divided into a plurality of groups and the hammering is continuously carried out for a fixed time by shifting the hammering start time of each group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating an electric precipitator capable of improving dust collection efficiency when the dust collection efficiency is reduced due to a change in operating conditions or the like.

[0002]

2. Description of the Related Art Generally, in an electric dust collector, as the operation time becomes longer, dust accumulates on the surface of a dust collecting plate to lower the dust collecting efficiency. As shown in FIG. 6, the dust collecting plate 5 is intermittently hammered by a hammering device 6 to mechanically remove the adhered and deposited dust, as shown in FIG.

However, in an electric precipitator for treating exhaust gas from a sintering machine, the concentration of dust contained in the exhaust gas, oil content, alkali components, and moisture in the dust are reduced depending on the mixing conditions and operating conditions of the raw materials. Change. For example,
As shown in FIG. 5, the alkali components (Na, K) in the dust vary greatly depending on the quicklime addition percentage of the sintering raw material in order to improve the permeability of the raw material. In this case, the alkali component in the dust tends to increase rapidly when the percentage of quicklime added exceeds 3.5%.

[0004] In particular, it is considered that oil, alkali components and moisture in the dust contained in the dust make it difficult to separate the dust deposited on the dust collecting plate by hammering. Among them,
A method to eliminate the difficulty of peeling due to oil in the dust,
It is proposed in Japanese Patent Application Laid-Open No. Hei 1-266866. this is,
After raising the inlet gas temperature of the electric precipitator to 150 ° C. to 200 ° C. and continuously maintaining the temperature for a long time, hammering the precipitating plate to remove the oil-containing dust layer attached to the precipitating plate , To resume dust collection.

[0005]

However, the method disclosed in Japanese Patent Application Laid-Open No. 1-266866, in which the temperature of the inlet gas of the electric precipitator is raised and maintained for a long time, is disclosed in Japanese Patent Application Laid-Open No. Hei 1-266866. Can be changed to an easily peelable property, but there are problems in the following points.

In a sintering apparatus, a large amount of air leaks inevitably occur and the oxygen concentration in the exhaust gas is high. If the oil content in the dust is large, the oil content and the carbon content in the dust may be burned due to the high temperature. In particular, since the dust deposition distribution on the dust collecting plate is not uniform, if such combustion occurs, the dust collecting plate is subjected to uneven heating and thus bends, cannot be charged, and the dust collecting ability is greatly reduced.

Further, as shown in FIG. 3, as the percentage of quicklime added to the sintering raw material is increased, the moving speed of dust ω (m / se
c) (the speed at which dust moves toward the dust collecting plate, which is obtained from the “Deutsch equation: Equation 1”), is A (0.03 to
Since it is reduced from 0.04 m / sec) to B (0.01 m / sec), there is a problem that the dust collection efficiency is reduced.

[0008]

(Equation 1)

[0009] The present invention solves the problems caused by the burning of oil and carbon in dust, and also operates an electric precipitator capable of preventing a reduction in dust collection efficiency even when the amount of quicklime added is increased. The purpose is to provide.

[0010]

SUMMARY OF THE INVENTION The present invention provides the above object,
This is achieved by the following method.

According to the first aspect of the present invention, when carrying out uncharged continuous hammering at regular intervals, the charged sections are divided into a plurality of groups, and the hammering start time of each group is shifted to perform the hammering continuously. .

According to this method, the dust layer which does not peel off by ordinary intermittent charging hammer can be reliably peeled off. Further, since the hammering start time is shifted for each group, it is possible to suppress an increase in the outlet dust concentration.

[0013] The method of claim 2 is the method of claim 1, wherein the temperature of the gas at the inlet of the electrostatic precipitator is maintained at 130 ° C or less.

According to this method, it is possible to eliminate bending of the dust collecting plate caused by combustion of oil and carbon in dust attached to the dust collecting plate and a state in which charging is impossible. This means
This is also the reason for limiting the gas temperature at the inlet of the electrostatic precipitator to 130 ° C. or lower.

[0015] The method of claim 3 is performed in the method of claim 1 or 2 when 3.5% or more of quicklime is added to the sintering raw material.

According to this method, it is possible to prevent a reduction in dust collection efficiency caused when a large amount of quicklime is added.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is characterized by operating under the following conditions in order to solve the above-mentioned problems. That is, one of them is to reduce the gas temperature at the inlet of the electric precipitator to a normal temperature (100 ° C.) in order to prevent the dust collecting plate from being bent due to the burning of oil and carbon in the dust.
C. to 110 C.). Second, in order to peel off and remove a dust layer firmly attached to the surface of the dust collecting plate due to oil or the like, uncharged continuous hammering performed in an uncharged state is performed at regular intervals. Third, in order to prevent a sudden increase in the dust concentration at the outlet of the electrostatic precipitator by simultaneously performing uncharged continuous hammering on a wide range of dust collectors, the range of dust collectors that simultaneously perform uncharged continuous hammering should be minimized. Set to a small range.

Here, uncharged continuous hammering means 30 to 40
For the usual intermittent charging hammer that performs one hammer every minute,
A hammer is performed once every 1 to 2 minutes in an uncharged state.

Next, an embodiment of the present invention will be described with reference to the drawings. First, an example of the configuration of the charging compartment of the electric precipitator will be described with reference to FIG. The electric precipitator 1 of this example has:
When viewed in a plane, No. 2 has two dust collecting chambers at the center. 1
Dust collector and No. No. 2 dust collector, and 1 and N
o. No. 2 on the outside of the dust collector. No. 3 dust collector No. 3a dust collection chamber and No. 3 3b A dust collection chamber is provided. As shown in the figure, each dust collection chamber has four sections 1 s to 4 s that can be turned on and off.

Then, the exhaust gas from the sintering machine flows through the duct represented by a line as shown by →, is divided and enters each dust collector.
Here, dust contained in the exhaust gas was collected, and the cleaned gas was No. 1; No. 1 dust collector and No. 1 No. 3a dust collection chamber is sucked by the blower 2a. No. 2 dust collector and No. 2 3b
The dust collection chamber is sucked by the blower 2b, discharged to the chimney 3, and released to the atmosphere.

The present inventors have found that quick lime is used as a sintering raw material in an amount of 3.65.
%, The operation of the method of the present invention was carried out at intervals of 2 days and 4 days for performing uncharged continuous hammering. Here, FIG. 1 shows an example of the uncharged continuous hammering schedule for each section when the interval is set to two days.
This schedule was organized so as to satisfy the following conditions. Divide the dust collectors into two groups, one on day 1 and the other on day 2. At the same time, the uncharged hammer performs two sections, the uncharged continuous hammering duration of one section is 2.5 hours, and the hammering start time of each section is shifted by 1.25 hours. here,
It goes without saying that a section that has been subjected to uncharged continuous hammering immediately returns to the state of dust collection by ordinary intermittent charged hammering.

FIG. 4 shows the change in the dust concentration at the outlet of the dust collector (mg / Nm ³ ) when the apparatus was operated with an uncharged hammering interval of 2 days. Before starting the operation of the present invention, although the dust collecting device outlet dust concentration was 50 mg / Nm ^3, after the implementation of this invention, and gradually decreases with the passage of days, become 20 mg / Nm ³ to day 14, After that, the result was better than expected that the value was flat. On the third day, the dust concentration temporarily increased suddenly because a large amount of the dust that had accumulated so far was peeled off in a large amount. Thereafter, such a phenomenon was not observed. In addition, the operation was performed with an uncharged hammering interval of 4 days. However, as shown in FIG.
/ sec) did not increase, and no improvement in dust collection efficiency was observed. Therefore, the uncharged hammering interval is preferably 1 to 3 days.

[0023]

According to the present invention, since the uncharged continuous hammer is performed at regular intervals with the inlet gas temperature kept at the normal value, the oil content in the dust by increasing the inlet gas temperature of the electrostatic precipitator is increased. In addition, it is possible to obtain an excellent effect that the problem caused by the burning of the carbon content can be solved and the dust collection efficiency can be prevented from lowering due to an increase in quicklime addition%.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an uncharged hammering schedule for each section of the method of the present invention.

FIG. 2 is a diagram showing a configuration of a charged compartment of an electric dust collector in which the method of the present invention is performed.

Fig. 3 Sulfur raw material addition percentage of sintering raw material and dust transfer speed (m / s)
It is a relation scatter diagram of (ec).

FIG. 4 is a transition diagram of a dust concentration at a dust collector outlet when the method of the present invention is performed.

FIG. 5: Quicklime addition percentage of sintering raw material and alkali percentage in dust
FIG.

FIG. 6 is a perspective view of a hammer of the dust collecting plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric dust collector 2a, 2b Blower 3 Chimney 1s-4s Section 5 Dust collecting plate 6 Hammering device

Claims (3)

[Claims] The present invention is characterized in that, in performing uncharged continuous hammering at a constant interval, charged sections are divided into a plurality of groups, and the hammering start time of each group is shifted to perform continuous hammering. How to operate the device. 2. The method for operating an electric precipitator according to claim 1, wherein the gas temperature at the inlet of the electric precipitator is maintained at 130 ° C. or lower. 3. The method for operating an electric precipitator according to claim 1, wherein the operation is performed when 3.5% or more of quicklime is added to the sintering raw material.