JPS5957117A - Method for purging dust of dust-containing gas flow amount measuring perforated type pitot tube - Google Patents

Abstract

PURPOSE:To enhance measuring accuracy, by providing a cut-off valve to the lower part of a perforated pitot tube provided to the wind leg of a sintering machine so as to be inclined with respect to a horizontal line and to expose the lower end part thereof to the outside to intermittently open said valve. CONSTITUTION:Because a perforated pitot tube 9 is provided in a wind leg 4 so as to cross the same at right angles in a spanned state, the pitot tube 9 itself is provided in an inclined state with respect to a horizontal line. The perforated pitot tube 9 is attached through a flange 10 so as to expose the lower end part 9A thereof to the air and a cut-off valve 11 is provided to the part exposed to the air. By intermittently opening the cut-off valve 11, the air is sucked into the pitot tube 9 by the pressure difference with the atmospheric pressure to be injected into the wind leg 4 from total pressure orifices 16 and dust precipitated downwardly in a total pressure chamber 20 is mixed with the air to be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dust purging method for a porous pitot tube for measuring the flow rate of a dust-containing gas.

Dwy) oite type sintering, l1ll (hereinafter referred to as sintering machine) is a downward suction type, so it uses a number of wind boxes installed below the sintering machine and branch pipes, or wind legs, connected to these. Sintering is carried out while drawing in the atmosphere, and the drawn exhaust gas is collected in the main duct, passed through an exhaust gas cleaning device such as a dust removal device, and then released from the chimney.

For sintering operations, it is essential to know the amount of gas sucked from the wind leg gas, and an exhaust gas flow meter is installed on the wind leg to measure the amount of exhaust gas from the exhaust gas flow rate per unit time.

Methods for measuring the gas flow rate include orifice,
There are methods using a venturi, an insertion type turbine meter, a hot wire anemometer, etc., and there is also a method using a porous pitot tube as disclosed in Japanese Patent Publication No. 10005/1983.

Among these methods, the method using a porous pitot tube has been used to measure the exhaust gas flow rate in the wind leg of a sintering machine because it allows the measurement of the average flow rate in the cross section of the branch tube.

However, the exhaust gas discharged from the sintering machine differs depending on the position in the longitudinal direction of the sintering machine, but because it contains dust and moisture, dust may enter the porous pitot tube or accumulate around the total pressure hole. This may narrow the hole or close the hole, reducing the accuracy of flow rate measurement or making measurement impossible.

In other words, the total pressure holes of the porous pitot tube are, for example, 5 mφ, and a plurality of holes are provided at fathom intervals along the length of the pitot tube, and these total pressure holes are provided facing each other in the flow direction of the dust-containing gas, so that the total pressure can be reduced. Dust enters through the holes and gradually accumulates in the total pressure chamber. Dust accumulates at a rate of 10 cry/hr in many places, and in a pitot tube of a total pressure chamber with an internal volume of 900 -
Not only does it become full within a few days, making it impossible to receive pressure in the total pressure chamber, rendering it useless as a differential pressure detector, but if left unattended, it will solidify internally due to the temperature and moisture in the gas, and will eventually be discarded. Become.

Furthermore, the combination of fine powder dust and mist in the gas adheres to the upstream outer wall of the porous pitot tube and grows, reaching a thickness of about 20 m in many places, blocking the total pressure hole.

In this way, the porous Vito tube provided in the wind leg of the sintering machine becomes clogged with dust in the exhaust gas from inside and outside, so that it no longer functions as a differential pressure detector.

Conventionally, there was no appropriate method for eliminating such harmful effects of dust in exhaust gas, and the only way to do so was to periodically clean it manually.

This cleaning work involved, for example, removing dust from the total pressure chamber every three days and removing dust attached to the outer tube every two months, but since there were a large number of porous pitot tubes, the effort required for maintenance was enormous. There is a problem in that it has a large effect on accuracy, and improvements have been desired.

The present invention has been made in view of this situation.

The present invention will be explained below based on the drawings.

Figure m1 is a diagram explaining the outline of the sintering machine, and the sintering machine consists of 1,1. The ore feeding device (
(not shown) continuously supplies the raw material and ignites the surface layer of the raw material in the ignition furnace 2.) Wind boxes 3, 3.・
... Sintering is performed while sucking exhaust gas through the wind leg 4, and the sintered ore is continuously discharged in the ore discharge section 1G. In the figure, 5 is a main duct, 6 is a dust collector, 7 is a blower, and 18 is a cicada.

FIG. 2 is a cross-sectional view illustrating the porous pitot tube according to the present invention and the installation situation of the pitot tube, and FIG.
It is a view from arrow A.

As shown in FIGS. 2 and 3, the porous pitot tube 9 according to the present invention is installed so as to be perpendicular to the inside of the wind leg 4. Originally, the wind leg 4 is installed so as to be bifurcated from the left and right sides of the wind box 3, so if it is installed perpendicular to the wind leg 4 circle, the perforated pitot tube 9 itself will be tilted with respect to the horizontal line. will be installed.

Porous pitot tube 9 according to the present invention, its lower end 9A
is attached via a 7-lunge 10 so as to be exposed to the outside air, and a shutoff valve 11 is provided in the portion exposed to the outside air. In the figure, 12 indicates a packing, and 13 indicates a bag nut.

The porous pitot tube 9 is formed of a large diameter pipe 14 and a small diameter pipe 15, and has a plurality of total pressure holes 16 at the contact point between the large diameter pipe 14 and the small diameter pipe 15, and also has a plurality of holes on both sides of the large diameter pipe. static pressure holes 17t are provided inside the small diameter pipe 15 to form a total pressure chamber 20. Special Publication No. 55-10 in which the space formed between the small-diameter knob 15 and the large-diameter pipe 14 is used as a static pressure chamber 21
It may be of the type shown in Japanese Patent No. 005, and when this porous pitot tube 9 is installed in the wind leg 4, the total pressure hole 16 is installed so as to face the gas flow shown by the arrow 18.

In the figure, 19 indicates dust that has adhered and accumulated on the outer surface of the porous pitot tube, and 22 indicates dust that has entered the total pressure chamber, settled down due to its own weight, and accumulated at the lower end of the total pressure chamber 2o.

The present invention provides a cutoff valve 11 at the lower end of a porous pitot pipe 9, which is installed in the wind leg 4 so as to be inclined with respect to the horizontal line, and its lower end is exposed to the outside air. 11 is opened intermittently, the outside air is sucked into the pitot tube 9 due to the difference in pressure from the atmospheric pressure, and is ejected from the total pressure hole 16 into the wind leg 4 and settles downward in the total pressure chamber 20. The purpose is to mix the dust 22 with outside air and remove it.

That is, the wind box 3 and wind leg 4 of the sintering machine
The purpose is to remove dust inside the porous pitot tube by using negative pressure, which is about -2,000 m below zero under normal operating conditions.

This invention is particularly effective for removing dust inside the line pressure chamber 20, but when the pedestal gas is ejected from the total pressure chamber 20 into the wind leg 4 through the multiple total pressure holes 16, the inside of the total pressure holes 16 is In addition to cleaning the dust 19 that has accumulated on the outer periphery of the large diameter pipe 14 near the total pressure hole 16, that is, the outer periphery of the multi-hole pitot tube 9, it is possible to simultaneously remove the dust that has settled and accumulated inside and outside the iD multi-hole pitot tube. Can be removed.

Furthermore, although it has been explained that the shutoff valve 11 according to the present invention is provided at the lower end 9A, it can also be provided at the upper end 9B in addition to the lower end 9A. It can also be applied to cleaning the static pressure hole 17. Furthermore, according to the present invention! ! A suitable valve 11 is a type that has good airtightness and does not cause dust to be trapped when the lid is closed, such as a ball valve.

The opening and closing of the blocking surface in the present invention can be performed fully automatically based on a preset time schedule. If a large number of pitot tubes are installed, such as installing a porous pitot tube on one side or both sides of each wind leg, it is best to open each shutoff valve at the same time to perform dust purging. This is not preferable because it causes a sudden change in the load on the blower 7, so it is preferable to divide the sintering machine into several blocks in the longitudinal direction and perform dust purging for each block, or to perform dust purging at random.

As described above, according to the present invention, the dust and -R-di of the porous pitot tube installed in the wind leg of the sintering machine can be easily removed without human intervention or without the need for a high-pressure gas source or its piping. This improves the measurement accuracy of "exhaust gas flow" using a porous pitot tube, extends the life of the pitot tube,
Furthermore, it has remarkable effects such as contributing to labor saving.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating an overview of a sintering machine, FIG. 2 is a cross-sectional view illustrating a porous pitot tube according to the present invention and the installation situation of the pitot tube, and FIG. A is a view in the direction of arrows. l: armlet, 2... ignition furnace, 3... quindodex, 4: wind leg, 9: porous pitot tube, 9A
: Lower end, lO: Turange, 11: Shutoff valve, 14:
Large diameter hole, 15: Small diameter hole, 16 two total pressure holes, 1
7: Static pressure hole, 19: Dust, 20: Total pressure chamber, 21...
Static pressure chamber, 22: Dust agent Patent attorney Aki Sawa
Masamitsu and 2 other Commissioners of the Japan Patent Office, Mr. 1, 'It ('1.') Indication Patent Application No. 168138 3, Relation to the person who makes the extraction, applicant 11, Place (residence) Tokyo 2-6 Otemachi, Chiyoda-ku, Miyako;
No. 3 Name (Name) (665) Nippon Steel Corporation 4
To the east (Tokyo Chuo-ku 1), 12-1 Taiyo Hills, Honkyo Kabuto-cho, I City, Showa era
Year, month, day (shipment) 6, ? ili, the number of inventions that increases from + White Contents of the amendment 1. The name of the claimed invention is changed as follows. 2. The scope of the claims of the present application is amended as follows. [(1) Install a pitot tube on the wind leg of the sintering machine with the lower end exposed to the outside, with the lower end exposed to the outside, and a cutoff valve is provided at the lower end of the pitot tube. A dust purging method for a pitot tube for measuring the flow rate of dust-containing gas, which is characterized by opening a shutoff valve intermittently. 3. In the 8th line from the bottom of page 21 of the specification, ``The present invention relates to...a pitot tube.'' The present invention relates to a pitot tube for measuring the flow rate of a dust-containing gas.
"Preferably a porous pitot tube." 4 Insert the following between lines 7 and 8 on page 18 of the same month. "Although the above embodiments have been explained using a multi-hole pitot tube as an example, it goes without saying that the present invention can also be applied to a single-hole pitot tube." 101

Claims (1)

[Claims] (1) A multi-hole pitot tube is installed on the wind leg of the sintering machine with the lower end thereof being exposed to the outside, with the lower end thereof being exposed to the outside, and a cutoff valve is provided at the lower end of the pitot tube,
A dust purging method for a porous pitot tube for measuring a dust-containing gas flow rate, which is characterized by opening this shutoff valve intermittently.