JPS5842735A - Blowing device for powder - Google Patents

Abstract

PURPOSE:To make stable operation possible by providing pressure measuring devices on the upper stream and down stream sides of a conveying pipe, and a measuring device for weight of powder in the powder introducing part to the conveying pipe, inputting measured values to an arithmetic device and controlling the opening and closing of a control valve by means of the arithmetic device in accordance with the measured values. CONSTITUTION:Pressure measuring devices are provided at the points P1 and P2 of a powder conveying pipe 3 of a blowing device for powder, and a measuring device 7 for weight of powder is provided in the powder introducing part to the pipe 3. The pressure p1 measured with the pressure measuring device at the point p1, the pressure p2 measured with the pressure measuring device at the point P2 and the introducing weight W of the powder measured with the device 7 are inputted to an arithmetic device C. The device C operates the P1 value by the equation (K1, K2 are constants specific to the device) from a desired rate of ejection of a gas (variable constant) and the actually measured values p2, W. The device C controls a control valve 6' so as to change the actually measured p1 value to the calculated p1 value.

Description

[Detailed description of the invention] The present invention relates to an apparatus for blowing powder into a molten metal bath.

It often occurs in the metallurgical field that powder must be injected into a bath of molten metal, such as when desulfurizing agents are injected into molten steel in the ex-furnace smelting of steel.

Conventionally, for this purpose, although there are various modifications, essentially a sealable powder container is provided with a powder quantitative discharge device at the bottom of the container, and the powder can be supplied from a single supply source. 112 streams of high pressure gas, one end connected to the head space of the vessel;
A device has been used in which the other end is connected to a long transport pipe and a silance pipe via the outlet of the powder quantitative discharge device.

When actually operating such a device, an important requirement for everyone is to ensure that the amount of gas ejected from the lance pipe varies as much as possible even if various other conditions change. That is,
One way to solve this problem is that in conventional equipment, the amount of powder contained in the carrier gas, the depth of immersion of the lance pipe into the molten metal, etc. have to fluctuate significantly each time they change. Insert a constant flow valve in the flow path from the high-pressure gas source to the device.

It is to supply a constant amount of gas regardless of changes in transport conditions.

However, this method can only deal with cases where operating conditions change relatively slowly.

For example, when only gas is ejected into molten metal,
When you start introducing powder, the resistance of the pipeline increases accordingly, and you need to deal with it.

The pressure of the gas from the source must be increased, and in conventional devices with metering valves, the increase in pressure is commensurate with the increase in line resistance.

A portion of the constant flow of gas is used to compress the gas in the powder container, reducing the amount of gas ejected from the lance pipe, and the degree of this reduction is the larger the capacity of the powder container.

The greater the degree of pressure rise, the greater the increase, and in extreme cases, the ejection energy is insufficient, causing blockage of the lance l upper eve.

In order to improve these drawbacks, the pipeline from the high-pressure gas supply source is branched upstream of the constant flow valve, and Il'' is piped to the head space of the powder container without passing through the constant flow valve. Piping only to the metered discharge device via a constant flow valve.

A method has been proposed in which the pressure at a portion of the powder metering discharge device is measured and the flow i into the head space of the powder container is controlled based on the measurement result.

However, although this method somewhat improves the above-mentioned drawbacks, the problems still remain unsolved.

The present inventor developed the present invention by focusing on the fact that in order to solve the above-mentioned problems, it is important to constantly grasp the pressure changes in the portion near the lance/zobe of a long transport route and promptly deal with them. completed.

According to the invention, the high-pressure carrier gas supplied from one source is divided into two after passing through one control valve.

One end is led into the head space of a sealed powder container, the other end is led into the powder outlet at the bottom of the powder container, and a conveying pipe is provided from there to the blowing lance pipe. In a device that blows the body.

In order to always blow out a constant amount of violet gas from the lance pipe despite fluctuations in the pressure applied to the blowing lance pipe and fluctuations in the amount of powder introduced into the transport pipe, pressure is applied on the upstream and downstream sides of the transport pipe. A measuring device is provided at the powder outlet to measure the amount of powder introduced into the conveying pipe, and a computing device is electrically connected to these measuring devices and electromagnetically coupled to the control valve. is provided, and the computing unit is used to calculate the upstream pressure pipe such that the amount of gas ejected is equal to or greater than a predetermined value even if there are fluctuations in the pressure applied to the downstream side and the amount of powder introduced.

There is provided an apparatus characterized in that the opening and closing of the control valve is controlled based on the calculation result.

Next, the present invention will be specifically explained with reference to all the drawings.

FIG. 1 shows the concept of the typical conventional device mentioned above.

The powder blowing device is a conveying gas pipe system equipped with a constant flow valve 6t, which is led from a high pressure gas supply source (not shown), and has a powder container 1 and 2 equipped with a powder metering discharge device 2 at the bottom thereof. Branches into two downstream of the flow valve.

One side is a long conveying pipe 3 that passes through the outlet of the powder quantitative discharge device 2.
through which it leads to the lance pipe 4, and the rest to the head space of the powder container. Usually, a device 5 (a pulley for winding up in the figure) is provided for taking the lance pipe in and out of the molten metal (contained in a ladle, etc.), but this is not relevant to the present invention for the time being. . ) As mentioned above, in such a device.

It cannot cope with sudden changes in pressure that occur within the conveying pipe 5.

Fluctuations are mainly caused by changes in the immersion depth of the lance pipe, changes in the amount of powder introduced into the conveyance path, or both, and the pressure PI at the PL point on the upstream side of the conveyance tube
(!: It is sufficient to measure the amount W of powder introduced into the pressure cup JM pipe at the downstream @pz point and ensure that G is equal to or higher than a predetermined value regardless of the changes in these values. To date, there is no device that has been controlled after elucidating the relationship between them.

The present inventor referred to Fanning's equation regarding gas flowing through a flow path, and set several hypothetical equations based on H experiments regarding the flow of gas containing powder.

As a result of repeated experiments, the above pt, P2. Between W# and G.

It was discovered that the relationship p+2kiP22+K,G"2GW in 10 holds true with practical accuracy.

In the formula, Kt, Kt, G, and w2 can be appropriately determined and can be easily determined by experimenting in the atmosphere. Therefore, Pt point pPt
A pressure measuring device is provided at the point, and a powder amount measuring device is provided at the powder introduction part into the conveying pipe, and these measured values are input into one computing unit, and the above formula tGt - desired constant value is used for pl. By performing calculations to solve the problem, the value of p that should keep G at a predetermined value in that state is calculated.

However, the actually measured p value is different from that, so
The arithmetic unit calculates the difference between the calculated p, value and the actually measured p, value, and based on it, controls a command to adjust the opening degree of the control valve to change p, t to the calculated value. Give to the valve. The design and fabrication of such computing units and control devices is readily practiced today in the art, so there is no need to discuss them in detail.

In the apparatus shown in FIG. 1, the present inventor provided pressure measuring devices at points 28 and 21, provided a meter 7 in the powder introduction section 2 to measure the amount of powder introduced, and the valve 6 was not a constant flow valve. 2 manual valves. The pressure measuring device, powder discharge amount measuring device, etc. used here are all known. The capacity of the powder container is 400
1, the inner diameter of the conveying pipe 3 was 19 mm and the length was 5.1 m, and the wrinkle lance pipe had an inner diameter of 21.6 ms and a length of 4 m.

Using air as the gas, blowing out at a rate of 0.5 to 1.8 N- per minute, and introducing powder with a bulk specific gravity of 1.31 and a particle size of 100 mesh or less into the conveyance path at a rate of 0 to 23 per minute. death,
Operate the control valve 6 by hand so that G becomes constant and s' Pl
When +yKt' was calculated based on the results of actual measurements for 30 combinations of ypieGs'', values of 0.328.0-564 were obtained for this device, respectively.

Therefore, the inventor constructed a device as shown in FIG. This device is substantially the same as the device shown in FIG. 1, but as described above, pressure measuring devices are provided at points 28 and 27, and a meter 7 for measuring the amount of powder introduced into the powder introduction section 2 is installed. A computing unit C? is provided and separately performs the above calculation. However, the valve 6' is not a constant flow valve.

This is a control valve that opens and closes using electrical signals. The dimensions are as described above. This calculator is set to calculate (-fc, where p' is the actual measured value of pressure at 21 points)'f: and controls the control valve 6' so that it becomes 0 according to the Δp value. It was set to open and close.

In this case, the unit of pressure is atmospheric pressure, and the unit of G is Nm'/-.

The unit of W is auxiliary/-.

Using this equipment, Ca powder was injected into molten steel, and it was able to quickly respond to changes in the introduction of Ca and the immersion depth of the lance, and was able to continue stable operation.

In the case of the above embodiment, P11d powder introduction part and P2 are set at the base of the lance pipe, but they are not limited to this position, as long as the pressure at the upstream and downstream parts of the conveying pipe can be measured. .

The above formula shows the basic form At, and it is possible to make various modifications without changing the main idea of the formula, or alternatively,
For more complex cases, for example, in response to a sudden change in W, the indicated value of G itself is changed depending on the magnitude of the change over time.This method eliminates all the drawbacks of conventional devices. Ashi.

Its contribution to industry is enormous.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the concept of a typical conventional powder blowing device. FIG. 2 is a diagram showing the concept of the powder blowing device of the present invention. In these figures. 1.: Powder @ device 2: Powder quantitative discharge device 3: Powder conveyance pipe 4: Blowing lance snoop 6: Constant! valve
6': Control valve 7: Powder discharge amount measuring device C: Arithmetic unit 10: Molten metal bath Patent applicant Akihiko Tsunoda Representative Patent attorney Masahiro Matsui Figure 1

Claims (1)

Claims: High pressure carrier gas supplied from eleven sources. After passing through one control valve, it is divided into two parts, one leading into the head space of one closed powder container, the other leading into the powder outlet at the bottom of said powder container, and from there a further blowing lance pipe. In a device that blows powder into molten metal, which is equipped with a conveyor pipe leading to A pressure measuring device is installed on the upstream and downstream sides of the conveying pipe in order to cause the powder to be ejected from the pipe, and a device is installed at the powder outlet to measure the amount of powder introduced into the conveying pipe, and these distance measuring devices are also installed. A computing unit electrically connected to the control valve and electromagnetically coupled to the control valve is provided, and the computing unit controls the amount of gas ejected to a predetermined value even if there are fluctuations in the pressure applied to the downstream side and the amount of powder introduced. An apparatus characterized in that the upstream pressure is calculated as above, and the opening and closing of the control valve is controlled based on the calculation result. 2. The device according to claim 1. The pressure on the upstream side of the conveying pipe is Pt + the pressure on the downstream side 'kp. The amount of powder introduced into the conveying pipe is 6W, and the desired gas ejection amount is G.
(variable constant), p2. For each value of W, the arithmetic unit calculates p-P2! According to the formula (x, , x, constant specific to Fia position) based on K, G” + K, GW, p
, the value is calculated, and from the difference between it and the actually measured p value, e
A device characterized by: issuing a command to adjust the opening degree of a control valve so as to change a pI value into a calculated value.