JPS5817619Y2 - Backwash air pressure adjustment device for bag filters for electric furnaces - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a device for adjusting the backwash air pressure of a bag filter that removes dust from exhaust gas discharged from an electric furnace.

Generally, a bag filter has a plurality of dust collection chambers.

This requires a cleaning process to be carried out at regular intervals to remove dust that has adhered to the filter bag, so even if one of the chambers enters the cleaning process, the other chambers continue the dust collection process, causing the bag to dry. This is to ensure that the dust collection action of the filter as a whole continues.

As mentioned above, a headwind is generally used for leaning, but in order to achieve the effect of blowing off dust and extend the life of the bag, this headwind, that is, the f
The cleaning air pressure applied to the cloth is a major problem.

This cleaning air pressure does not change the air pressure that is processed by the bag filter.

If the cleaning air pressure is always constant, the air volume adjustment damper of the cleaning tact may be adjusted and fixed in advance to obtain the optimum cleaning air pressure.

However, in devices such as electric furnace dust collectors, which have a predetermined operating cycle and require the amount of air to be treated to be changed moment by moment depending on the operating conditions, the The pressure on the inlet and outlet sides of the exhaust fan changes.

Therefore, if the air volume adjusting damper of the cleaning duct is fixed, the cleaning air pressure will also change as the damper on the electric furnace side opens and closes, which is not preferable for the bag filter.

This idea aims to solve the above-mentioned problem.The cleaning duct is equipped with a pressure detection device and an automatic damper for adjusting air volume, and the detected value from the pressure detection device is fed back to the automatic damper control device. The present invention provides a bag filter equipped with a backwash air pressure adjustment device that controls a damper so that the air pressure inside the cleaning duct is always constant.

In the figure, reference numeral 1 denotes an electric furnace, and an exhaust gas duct 2 is connected to the electric furnace 1, and this duct 2 is connected to the suction port of an exhaust fan 3.

In addition, the duct 2 is provided with an air volume adjustment damper 4 and a cooling tower 5 to adjust the air volume according to the operating state of the electric furnace 1, and to keep the temperature at about the permissible temperature of the f cloth of the bag filter (approximately 250'C). It is intended to reduce the

A connecting dust 6 is connected to the discharge port of the exhaust fan 3, and this duct 6 is provided with a switching damper A for dust collection and cleaning.

This damper A has a duct 6 at the bottom of the main body 7 as shown in Figure 2.
are connected, a cleaning duct 8 is connected to the upper part,
The inlet 9 of the bag filter B is connected to the middle part.

Inside the main body 7, valve ports 1o and ii are provided on the upper and lower sides, and a valve plate 12 for opening and closing the valve ports is moved up and down by a driving device 13 such as an air cylinder to open and close the valve ports 10 and 11 alternately.

Reference numeral 14 denotes a pressure detection tube communicated with the inside of the duct 8, and this detection tube 14 is connected to a differential pressure transmitter 15 of the pressure setting device C.

This differential pressure transmitter 1-5 converts the pressure from the pressure detection tube 14 into a current value, and transmits the DC signal from this transmitter 15 to the setting device 16, which operates the control motor 17 depending on the magnitude of the DC signal. .

This motor 17 opens and closes an automatic damper 18 for adjusting air volume.

A plurality of cylindrical bags 19 made of one piece of cloth are installed in the dust collection chamber 20 of the bag filter B, and a gear gallery 21 is provided in the upper part of the chamber 20.

A plurality of dust collection chambers 20 are provided as shown in FIG. 1, and an inlet 9 having a switching damper A is provided in the hopper 24 at the bottom of each chamber 20, and the switching damper A of each chamber 20 is connected to a communication pipe 22.
23 communicates with the ducts 6 and 8.

This device has the above-mentioned configuration, and when the valve plate 12 of the switching damper A closes the valve port 10 and opens the valve port 11 as shown in FIG. The air volume is adjusted through 4.

The dust is cooled by the cooling tower 5, passes through the exhaust fan 3, passes through the duct 6, passes through the valve port 11 and the inlet 9, flows into the lower hopper 24 of the bag filter B, and flows into the bag 19 from the lower end opening of the bag 19, where dust is collected. The gas adheres to the inner surface of the bag 19, becomes clean, and is released from the gear gallery 21 into the atmosphere.

Next, when the valve plate 12 is switched to the cleaning side by the driving device, the valve port 11 is closed and the valve port 10 is opened.

For this reason, the dust collection chamber 20 is located at the entrance 9. Valve mouth 10. It communicates with the suction side of the exhaust fan 3 via the cleaning duct 8 .

In this case, the exhaust air from the exhaust fan 3 flows into the other dust collection chamber 20 through the communication pipe 22 and exits.

Therefore, the pressure in the dust collection chamber 20 switched to the cleaning side becomes negative, and external air flows into the dust collection chamber 20 from the gear gallery 21 and into the bag 19 from the outside of each bag 19 .

Therefore, the dust adhering to the inner wall of the bag 19 is peeled off by the collapsing action of the bag 19 caused by the reverse airflow, and is thrown off into the hopper 24 at the bottom of the collection chamber 20, where it is automatically discharged by the rotary valve 25. Ru.

This dusting operation is performed by operating the switching damper A of each dust collection chamber 20 using a preset program timer, and is performed to prevent the thickness of the dust adhering to each bag 19 from reaching a certain limit value. do.

As shown in FIG. 2, even if the switching damper A belonging to this dust collection chamber 20 closes the valve port 10, the damper A in any one of the other plurality of dust collection chambers 20 is switched to the cleaning side. Backwashing is performed by the duct 23°8.

Even during the above-mentioned backwashing, the air volume adjusting damper 4 operates according to the operating state of the electric furnace 1, and the air pressure inside the ducts 2 and 6 changes.

That is, since the exhaust fan 3 has a constant rotation speed, the amount of gas generated by the electric furnace 10 increases, and if the damper 4 is opened to a narrow position, the wind pressure inside the duct 2 decreases.

In addition, the amount of gas generated in the electric furnace 10 is reduced, and the damper 4
When the opening degree of the duct 2 is made small, the wind pressure inside the duct 2 increases.

Therefore, depending on the amount of exhaust gas generated in the electric furnace 10, the duct 2
Since the wind pressure inside changes, the automatic damper 18 for adjusting the air volume
If there is no.

The change in the wind pressure inside the duct 2 is proportional to the amount of air sucked through the cleaning duct 8, and when the wind pressure inside the duct 2 changes, the wind pressure inside the duct 8 also changes.

However, in the case of this invention, when the pressure of the backwash air flowing into the duct 8 changes due to a change in the wind pressure inside the duct 2,
This pressure change is transmitted from the pressure detection pipe 14 to the differential pressure transmitter 15, and the control motor 17 operates the damper 18 based on the signal from the transmitter 15 to maintain the pressure in the duct 8 at the set pressure.

That is, 1. For example, when the amount of gas generated in the electric furnace 10 is small,
When the wind pressure inside the duct 2 increases by reducing the opening degree of the damper 4, if there is no damper 18, the suction amount of the duct 8 will increase and a large amount of air will be sucked from the gear gallery 21 into the dust collection chamber 20. However, in the case of this invention, the damper 18 moves in response to changes in the pressure inside the duct 8 to maintain the pressure inside the duct 8 at the set pressure.

As mentioned above, this design ensures that the wind pressure during backwashing of the bag filter remains constant, unaffected by changes in the wind pressure in the exhaust gas duct caused by the air volume adjustment damper, which changes its opening depending on the amount of exhaust gas generated by the electric furnace. Therefore, the life of the e-cloth, etc. that constitute the bag, which is subjected to excessive wind pressure, is extended several times compared to a bag filter equipped with a conventional cleaning device.

Furthermore, since the backwashing pressure is constant, the cleaning action of the cloth is constantly performed at a constant level.

Therefore, there is no possibility of dust leakage due to excessive peeling of dust adhering to the surface of the cloth, or dust clogging due to insufficient peeling, and extremely stable operation can be achieved.

Furthermore, the cleaning air pressure adjustment is now automatically controlled, eliminating the need for manual adjustment, and the longer lifespan of the P cloth means longer bag replacement cycles, making maintenance easier and reducing running costs. This is a backwash air pressure adjustment device that is ideal for backwashing equipment for bag filters for collecting dust in electric furnaces where the amount of exhaust gas changes from moment to moment.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a bag filter implementing this invention.
FIG. 2 is a longitudinal sectional front view of the main parts same as above. 8...Cleaning duct, 14...
Pressure detection tube, 15...Differential pressure transmitter, 16...
...Setting device. 17... Control motor, 18...
・Air volume adjustment damper, A...Switching damper, B.
...Bag filter.

Claims (1)

[Scope of Claim for Utility Model Registration] The exhaust gas outlet of the electric furnace and the inlet of the bag filter having a plurality of dust collection chambers are connected by an exhaust gas duct, and an exhaust fan for sucking the exhaust gas is provided in the exhaust gas duct, and the exhaust gas is side and the entrance of each dust collection chamber)
A switching damper is installed at the entrance of each dust collection chamber to alternately switch the entrance to the exhaust gas duct and cleaning duct. In a backwashing device for a bag filter for an electric furnace, which has an exhaust gas air volume adjustment damper near the electric furnace in the exhaust gas duct,
Backwashing of a bag filter for an electric furnace, wherein the cleaning duct is provided with a pressure detection device and an automatic damper for adjusting air volume, and the pressure detection device controls the automatic damper for adjusting air volume to keep the backwash air pressure constant. Wind pressure adjustment device.