JPH01281159A - Method for preventing adhesion of scales on pipe for supply of washing water to dust collecting plates, nozzle and dust collecting plate in wet type electric dust collector - Google Patents

Abstract

PURPOSE:To enhance the removal effect of hard scales growing gradually by periodically stopping the supply of water for use in the washing of dust collecting plates in a wet type electric dust collecting device, so that steam alone is supplied to a header pipe for carrying the washing water to the dust collecting plates. CONSTITUTION:The supply of water for use in the washing of dust collecting plates in a wet type electric dust collector 1 is stopped periodically, so that steam alone is supplied to a header pipe 3 for carrying the washing water to the dust collecting plates. This method permits scales to be separated from pipe walls due to the differences in the amount of thermal expansion between the pipe wall and the solidified scale while the latter is blown off with the steam pressure and thereby the removal effect of the hard scales growing gradually is enhanced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a dust collection plate cleaning water pipe, nozzle, and dust collection in a wet electrostatic precipitator used for removing dust from byproduct gas generated in a blast furnace, converter, etc. The present invention relates to a method for preventing scale adhesion on plates.

(Prior technology) A wet electrostatic precipitator used to remove dust from byproduct gas generated from blast furnaces, etc. applies a high DC voltage between a dust collection plate and a discharge wire, and uses the electrostatic force to remove byproduct gas. The dust inside is attached to the dust collection plate, and water is supplied to the dust collection water sprinkling nozzle installed above the dust collection plate. 7. Supply cleaning water through the valve and water supply pipe to form a water film on the dust collection plate. It forms and washes away dust without causing it to stick.

In dust collectors, cleaning water is generally recycled after being treated as waste water for cost reasons.
Water quality is poor and scale is high. For this reason, scale adhesion occurs near the nozzle hole of the dust collecting water nozzle and near the interface between the dust collecting water spraying part and the non-sprinkling part of the dust collecting plate.

This scale adhesion causes poor spraying of the dust collection water, and if the scale adhesion grows further, it may cause nozzle clogging, failure to form a water film on the dust collection plate, and temporary dust sticking to the dust collection plate. This leads to a decrease in dust collection efficiency due to poor timing.

For this reason, in conventional wet electrostatic precipitators, JP-A-62-1
As shown in Japanese Patent No. 02845, a method is used in which an inert fluid is supplied at the same time as dust collection cleaning water, and the pressure thereof is used to prevent scale adhesion.

[Problem to be solved by the invention]

The conventional method for preventing scale adhesion on cleaning water spray nozzles described above prevents scale from gradually growing and hardening.
A fluid containing both steam and dust-collecting water is sometimes used, but the pressure of this fluid has a small scale removal effect, so the scale that has grown on the nozzle can be removed using an electrostatic precipitator in about 2 to 3 months. It needs to be stopped and cleaned.

The purpose of the present invention is to enhance the removal effect on this gradually growing hard scale.

[Means to solve the problem]

The present invention is a wet type electrostatic precipitator in which the supply of water for washing the dust collecting plate in the wet type electrostatic precipitator is periodically stopped, and only steam is supplied to the ladder pipe of the washing water for the dust collecting plate. This is a method for preventing scale adhesion on dust plate cleaning water piping, nozzles, and dust collection plates.

[Function] As described above, the present invention stops the dust collecting water and supplies only steam to remove the peeling due to the difference in thermal expansion between the hardened scale and the pipe wall. i+1, and has the effect of blowing away due to the pressure of steam.

(Example) The present invention is a wet electrostatic precipitator shown in FIGS. 1 and 2.
A plurality of dust collection water sprinkling nozzles 4 are installed on the header pipe 3 for ffi dust temporary cleaning, which is attached to the upper part of the dust collection plate 2 of No. 1 through the mounting flange 12, and a plurality of dust collection water sprinkling nozzles 4 are installed on the header pipe 3 for temporary cleaning of ffi dust, which is attached to the upper part of the dust collection plate 2 of 1 through the mounting flange 12. The dust water supply pipe 6 is connected to form a water film on the surface of the dust collection plate 2 and the collected dust is washed away. Separately, the steam supply pipe 5 branched from the 7 goo pipe 9 to the steam supply is connected to collect dust. It has a structure that allows it to be connected to the plate cleaning header pipe 3 and supply steam. The dust collection water supply piping 6 and the steam supply piping 5 include
Valves 8.7 are each operated by electric power or compressed air, and are opened and closed by a timer using a control device 11 for opening and closing the valves.

During regular operation, the dust collection water valve 8 is opened and the steam valve 7 is closed, forming a water film on the surface of the dust collection plate. Further, during scale cleaning, a timer is set so that the dust collection water valve 8 is closed and the steam valve 7 is opened.

Steam cleaning needs to be carried out at an appropriate frequency depending on the properties of attached dust, water quality, and pressure of steam used. - For example, if the steam pressure is 8-10 kg/cdG and the water quality (pH
:9 to 11), when the main component of the adhering dust was FeO, the effect of preventing scale adhesion was obtained with a steam cleaning frequency of once per cycle for several minutes.

〔Effect of the invention〕

As described above, the present invention provides a wet dust collector in which only steam is intermittently supplied to the header pipe for cleaning the dust collecting plate, thereby achieving a scale removal effect due to pressure and a difference in thermal expansion between scale and piping due to heat. Creates a peeling effect and enhances the effect of preventing scale adhesion on dust collection cleaning pipes and dust collection water spray nozzles.

Therefore, a stable dust collection water film is formed, and the stable operation of the dust collector and the maintenance of dust collection efficiency are achieved, and the frequency of scale cleaning such as temporary closure of the nozzle is reduced (maintenance frequency is once every 6 months to once a year). ).

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, and FIG. 2 is a layout diagram of the header pipe for cleaning the dust collecting plate and the dust collecting plate when FIG. 1 is viewed from above (view from arrow 8-A). , FIG. 3 is a diagram showing the details of the arrangement of the dust collecting plate water nozzle. Figure 2 Figure 3

Claims (1)

[Claims] Dust collector plate cleaning water in a wet type electrostatic precipitator, characterized in that the supply of dust collector plate cleaning water in the wet type electrostatic precipitator is periodically stopped and only steam is supplied to the header pipe of the dust collector plate cleaning water. Method for preventing scale adhesion on piping, nozzles, and dust collection plates.