JPS586389A - Method of operating dust collector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an efficient method of operating a dust collection system in which a dust collection device and a dust collection device are arranged in series.

Generally, combustible gases such as converter gas and blast furnace gas are often mixed using a two-stage venturi scrubber system. In order to achieve high dust collection performance, a large amount of pressure loss is required, which is not preferable in terms of energy saving. However, on the other hand, it functions as a large-capacity cooler for high-temperature gas.

On the other hand, electric dust multipliers require much less pressure loss than Pentury scrubbers, and can achieve high dust multiplier performance, making them highly effective as energy-saving models. However, in the case of high-temperature gas dust collection, the discharge current is large, resulting in energy savings, so it is necessary to install a cooler to cool down the inlet gas temperature to some extent.

Therefore, the electrostatic precipitator is a venturi scrubber that combines the advantages of an art dust collector.The electrostatic precipitator is a venturi scrubber that combines the advantages of an art dust collector.
By assigning the final dust multiplication performance to the electrostatic precipitator, an energy-saving dust collection system with low pressure loss and suitable for high-temperature gases can be constructed, which is promising as a future dust collection system.

By the way, in an electrostatic precipitator, a voltage is applied between a dust collecting electrode and a discharge electrode, and dust and mist in passing gas are collected on the dust collecting electrode using electric force (mainly Coulomb force), and the collected dust is released intermittently. By removing the dust periodically, stable dust collection performance can be achieved over a long period of time. However, when removing the collected dust, both dry and wet methods have the disadvantage of poor dust removal performance. That is, in the case of a dry electric dust duster, a hammering method is generally used to remove dust. During hammering, the dust collected on the dust collection pole separates from the pole and falls due to gravity, but the minute dust is re-dispersed into the gas flow and exits to the downstream side, which deteriorates the dust collection performance. do.

In the case of wet type electric dust multipliers, a cleaning method is generally used to remove dust. During cleaning, the dust collected on the dust electrode is washed with water, flows down the electrode surface as a slurry stream, and is discharged to the bottom. However, during cleaning, since the charging voltage becomes unstable, the charging chamber pressure is generally lowered or cut off, which deteriorates the dust collection performance.

As described above, since the dust collection performance of the electric dust multiplier deteriorates during the period of dust removal, the dust collection performance of the dust multiplier system as a whole consisting of the venturi scrubber and the electric dust multiplier also deteriorates.

The present invention aims to solve these problems and provide an extremely effective method of operating a dust collector.

The present invention will be explained below.

As shown in Figure 1, the dust multiplication performance of the Venturi scrubber improves as the pressure loss increases, but on the other hand, the operating cost increases. On the other hand, as shown in FIG. 2, the dust collection performance of the cloth air dust collector improves as the charging voltage is increased when the electrodes are of the same type.

Therefore, in a dust collection system in which a venturi scrubber and an electric dust multiplier are arranged in series, in order to reduce operating costs, the pressure loss of the venturi scrubber is usually reduced, and the charging chamber pressure of the electric dust multiplier is increased. A method of operating is preferred.

However, during the period when the dust collected by the electrostatic precipitator is removed from the dust collecting electrode and the discharge electrode, the dust collection performance of the electrostatic precipitator decreases, and the concentration of the dust at the system exit increases.

In the operating method of the present invention, when the dust multiplier performance of the electric dust multiplier deteriorates as shown in Fig. 3, the pressure drop of the Venturi scrubber is increased to compensate for the deterioration and the dust multiplier performance is improved, thereby improving the dust multiplier performance as a whole. The aim is to maintain the dust collection performance of

FIG. 4 shows an example of the pressure drop control loop of a venturi scrubber before and after cleaning during cleaning of a wet electrostatic multiplier that uses a simultaneous cleaning method for dust collecting electrodes and discharge electrodes.

In FIG. 4, the points ■, ■, ■, and ■ indicate the following operations.

■Point: Cleaning command timer is ON.

At this position, turn on the movable damper drive command so that the venturi scrubber pressure drop upper limit setting value is reached.

Point ■: Cleaning starts as soon as the venturi scrubber pressure drop upper limit setting is completed.■ point: The movable damper drive command is turned ON so that the venturi scrubber pressure drop lower limit setting value is reached as soon as cleaning is completed.

■Point: Venturi scrubber pressure drop lower limit position
The upper and lower limit pressure loss setting values for the lease scrubber may be set to the opening degree if the state quantities of the system, such as the gas amount, are stable.

Next, we will discuss the advantages of this operating method when applied to a blast furnace gas cleaning system.

Blast furnace gas cleaning equipment is generally a dust catcher (DC).
It consists of a ventilator scrubber and a ventilator scrubber, but due to recent energy saving needs, a furnace top pressure recovery turbine 2 (TRT) is installed on the downstream side to recover the excess pressure of the clean gas as electricity. ing. However, the gas purifier mentioned above is... Eight%. Yes, it is needed.

On the other hand, a dust catcher (D
C) + 1st Venturi Scrubber When using an electrostatic precipitator, the total pressure drop should be approximately 500 mmAq. Approximately 35
The pressure of oommAq leads to an increase in the electric power of the furnace top pressure recovery turbine.However, as mentioned above, the dust collection performance of the electric dust multiplier deteriorates during the period of removing the collected dust, so the amount of dust at the outlet increases. This dust causes dust (rubble) in the top pressure recovery turbine and dust troubles in the blast furnace gas utilization equipment on the downstream side, sometimes leading to the destruction of the turbine blades. has not been standardized.

However, if the operating method of the present invention is used, although the recovery pressure energy of the top pressure recovery turbine decreases during electroplating type cleaning, it is possible to prevent dust troubles in the top pressure recovery turbine and other equipment, increasing its reliability. The scrubber 10 electrostatic precipitator system can now be used as a blast furnace gas cleaning device without any problems, and the benefits are great.

There are various ways to change the pressure loss of a Venturi scrubber, but the main ones include 1) changing the opening of the movable damper, 2) changing the number of gases through the multi-throat, and 3) changing the amount of water supplied. .

[Brief explanation of the drawing]

Figure 1 shows the relationship between the pressure drop and dust collection efficiency of a venturi scrubber. Figure 2 shows the relationship between the charging voltage and dust collection efficiency of an electric dust multiplier. Figure 3 is a graph explaining the details of the present invention. FIG. 4 is a graph fully illustrating one embodiment of the method of the present invention.

Claims (1)

[Claims] In a dust collector/stem consisting of a venturi scrubber and an electrostatic precipitator arranged in series, the pressure loss of the venturi scrubber during the period of removing old dust attached to the collecting electrode or discharge electrode of the electrostatic precipitator. A method for operating a dust collector, characterized in that the pressure drop is made larger than the pressure loss of the Baturi scrubber during the period in which the gas l-k is not removed.