GB2094515A

GB2094515A - Converter waste gas recovering system

Info

Publication number: GB2094515A
Application number: GB8206762A
Authority: GB
Original assignee: Kawasaki Heavy Industries Ltd; Kawasaki Jukogyo KK
Current assignee: Kawasaki Heavy Industries Ltd; Kawasaki Motors Ltd
Priority date: 1981-03-09
Filing date: 1982-03-08
Publication date: 1982-09-15
Also published as: GB2094515B; JPS57149410A; JPH0129851B2; DE3207696C2; DE3207696A1

Abstract

A converter waste gas recovering system includes a hood (3) mounted above a converter (1), and a skirt (2) interposed between the hood and a furnace mouth of the converter for elevatory movement by hydraulic means (15) to provide a seal between the furnace mouth and the hood. Adjustments of the skirt can be automatically effected in accordance with the condition of the skull deposits (17) on the furnace mouth to bring the minimum value of the gap between the upper end of the skull deposits and the skirt into agreement with a value set beforehand. The system includes a plurality of industrial T.V. cameras (10) for monitoring the deposition of the skull on the furnace mouth; control means (11, 12, 13, 19) for sensing a deviation of the value of the gap between the skirt (2) and the skull deposits monitored by the industrial television cameras (10) from the minimum pre-set value and for generating a signal corresponding to the deviation; and hydraulic servo means (14) actuated by the signal to actuate the hydraulic means (15) for operating the skirt (2). <IMAGE>

Description

SPECIFICATION Converter waste gas recovering system This invention relates to a converter waste gas recovering system. It is particularly concerned with a converter waste gas recovering system wherein a gap between the furnace mouth of the converter and a skirt at the lower end of a hood associated with the furnace mouth can be automatically adjusted, thereby to avoid damage that might otherwise be caused to the skirt and carry out recovery of the converter waste gas with a high degree of efficiency.

Reference will first be made to Figure 1 of the accompanying drawings, in which there is shown, in diagrammatic form, a known converter waste gas recovering system.

In converter operation, oxygen blown into the converter reacts with carbon contained in pig iron charged into the converter to produce a large quantity of CO gas. This CO gas is recovered as a valuable gas by a converter waste gas recovering system. In Figure 1 the converter is referenced 1.

Pure oxygen blown into the converter 1 through an oxygen blowing lance 8 reacts with the carbon contained in the pig iron in molten state charged into the converter 1, 50 that decarburisation occurs and a large quantity of CO gas is generated in the converter 1. The CO gas is drawn from the converter 1 to a hood 3 by an induced draft fan 5 to be cooled therein. After being cooled, the gas is scrubbed by scrubbers 4 before being stored in a gas holder 6 as a valuable gas.

The converter 1 is provided with means for tilting it when molten steel is introduced thereinto from a blast furnace, or a so-called tapping operation is performed for taking out molten steel that has been decarburised. To enable tiiting of the converter 1 to take place, an elevating skirt 2 is installed between the converter 1 and the hood 3. When the converter 1 is to be tilted, the skirt 2 is lifted to form a gap of sufficient size between the converter 1 and the hood 3. In the non-tilted condition, to avoid CO gas leaks and invasion of air at the gap between the converter 1 and the hood 3 when blowing is performed, the gap between the converter 1 and the hood 3 is eliminated by moving the skirt 2 downwardly.

At the initial and terminating stages of blowing operation, to replace the air or the gas existing in the system with an inert gas layer produced by combustion of the generated gas, it is usual practice to draw ambient air through the gas between the skirt 2 and the converter 1 into the converter 1 to cause combustion to take place, and to release the products of this combustion through a smoke stack 7. Thus the skirt 2 is lifted each time at a charge of the converter 1. This makes it necessary to adjust the gap between the skirt 2 and the converter 1 each time the skirt 2 is lifted.

The skirt lifting operation has hitherto been performed by an operator who relied on the naked eye for carrying out observations to effect necessary adjustments of the gap. Difficulties have hitherto been experienced in effecting gap adjustments in this way. During blowing, slug formed in the converter 1 and metal projection flying from the converter 1 are successively deposited on the furnace mouth of the converter 1 to form skull deposits. The skull deposits formed on the furnace mouth show changes in volume and shape with time during blowing. If the skirt is kept stationary for a substantial period of time, the melt on the skull that increases in quantity will adhere to the skirt, thereby crippling skirt lifting and interfering with furnace operation.

Thus the need arises to move the skirt in elevatory movement in a manner to match the skull deposits deposited on the furnace mouth, the operator observing the formation of the skull deposits with the naked eye and manually actuating the skirt by remote control. The skull is deposited not oniy on the front of the furnace mouth but also at the back of the furnace mouth.

However, it is quite difficult to judge the volume and shape of the skull deposits all around the furnace mouth. Thus it has hitherto been the usual practice for the operator to provide a reserve to the gap between the skirt and the furnace mouth absolutely to avoid contact between the lower portion of the skirt and the skull deposits. As a result, the gap between the skirt and the furnace mouth has been held greater than is necessary to keep the minimum clearance around the furnace mouth and increase the CO concentration in the gas. This has led to a reduction in the value of the exhaust gas as a valuable gas.

In an age of energy conservation such as the one we now live in, it is earnestly desired that the aforesaid disadvantages be obviated to improve the value of the exhaust gas. This had raised a serious technical problem from the point of view of how to carry out efficiently converter waste gas recovery.

According to the present invention there is provided a converter waste gas recovering system comprising: a hood mounted above a converter; a skirt interposed between the hood and a furnace mouth of the converter for elevatory movement by driving means to provide a seal between the furnace mouth and the hood; a plurality of industrial television cameras installed in the vicinity of the furnace mouth to monitor deposition of skull on the furnace mouth; control means for sensing a deviation of the value of the gap between the skirt and the furnace mouth as monitored by said cameras from a minimum pre-set value of this gas and for producing a signal corresponding to the sensed deviation; and means operative in response to a signal from said control means to actuate said driving means for moving the skirt in elevatory movement, whereby the skirt opening can be automatically adjusted in accordance with skull deposition on the furnace mouth to bring the minimum value of the gap between the skirt and the furnace mouth into agreement with said minimum pre-set value.

This system enables the CO gas produced in the converter to be recovered with a high degree of efficiency.

For a better understanding of the invention and to show how the same may be carried into effect reference will now be made, by way of example, to Figure 2 of the accompanying drawings in which a converter waste gas recovery system is shown in diagrammatic form.

Referring to Figure 2, a hood 3 is located above a converter 1, and a skirt 2 is located between the hood 3 and the converter 1 through water sealing means 1 6 for elevatory movement by actuation of a hydraulic cylinder 1 5. Numeral 1 7 designates skull deposits formed on the furnace mouth by accumulation of slag generated in the converter 1 while refining is being carried out with pure oxygen blown into the furnace 1 through an oxygen blowing lance 8 and metal projection scattered from within the converter 1. Numeral 9 designates a cooler.

Numeral 10 designates a plurality of industrial television cameras (ITVCs for short) installed in the vicinity of the furnace mouth. Numeral 11 designates an image processor operative to determine the gap between the skirt 2 and the furnace mouth of the converter 1 by converting the images obtained by the ImiCs 10 into "1" and "0" binary signals in accordance with the brightness of the picture elements. Numeral 19 designates a minimum gap value selector for selecting the minimum value from all the values of the gap sensed by the image processor 11.

Numeral 12 designates a skirt opening setter for limiting the gap between the skirt 2 and the furnace mouth of the converter 1 to a minimum value. Numeral 13 designates an arithmetic unit for calculating a deviation of the minimum value selected by the minimum gap value selector 19 from the value of the gap set by the skirt opening setter 12. Numeral 14 designates hydraulic servo means actuated by a signal from the arithmetic unit 13.

The minimum value of the gap between the skirt 2 and the furnace mouth of the converter 1 is set beforehand by the skirt opening setter 12. The gap of this size is large enough both to prevent CO gas leaks to outside from the converter 1 and to avoid entry of the ambient air into the converter 1 when the pressure in the converter 1 is controlled by means of an induced draft fan such as the fan 5 described above with reference to Figure 1. The skull deposits 1 7 formed on the furnace mouth of the converter 1 are monitored by the lWCs 10 installed in the vicinity of the furnace mouth, and images are supplied from each lTVC to the associated image processor 11 at a rate of, for example, 30 frames per second.The images supplied to each image processor 11 are determined as to whether they are normal or abnormal. Then the gap between the skirt 2 and the furnace mouth of the converter 1 is calculated on the basis of the binarized images, and signals representing the gap values are fed to the minimum gap value selector 1 9 which selects the minimum value of the gap from all the gap values supplied from the image processors 11 of the ITVCs 10 and feeds this minimum value to the arithmetic unit 13. The arithmetic unit 13 compares the signal from the minimum gap value selector 19 with the signal from the skirt opening setter 12 and calculates a deviation of the former from the latter.Then the arithmetic unit 1 3 generates a deviation signal and feeds this signal to the hydraulic servo means 14 to actuate this means. A supply of hydraulic fluid is introduced into ether the rod side chamber or the head side chamber of the cylinder 1 5 as the case may be from a hydraulic fluid source 1 8, thereby to effect adjustments of the gap between the skirt 2 and the converter 1 by moving the skirt 2.

From the foregoing description, it will be appreciated that a plurality of lWCs is installed in the vicinity of the furnace mouth of the converter, to enable accurate information on the skull deposits formed on the furnace mouth to be positively obtained in spite of such skull deposit formation taking place irregularly. Also, the provision of the image processors and the minimum gap value selector enables the minimum value of the gap between the skirt and the furnace mouth to be selected so as automatically to allow the skirt to be moved either upwardly or downwardly by bringing the gap of the minimum value into agreement with the set gap. Thus contact between the skirt and the deposits on the furnace mouth can be avoided to prevent adhesion of skull to the skirt, and at the same time the minimum gap can be provided between skirt and furnace mouth at all times.

Thus it is possible to avoid damage to the skirt while it is possible to effect recovery of the gas of high CO concentration with a high degree of efficiency thereby increasing the value of the converter waste gas as a valuable gas, and thus contributing to energy conservation.

Claims

1. A converter waste gas recovering system comprising: a hood mounted above a converter; a skirt interposed between the hood and a furnace mouth of the converter for elevatory movement by driving means to provide a seal between the furnace mouth and the hood: a plurality of industrial television cameras installed in the vicinity of the furnace mouth to monitor deposition of skull on the furnace mouth; control means for sensing a deviation of the value of the gap between the skirt and the furnace mouth as monitored by said cameras from a minimum pre-set value of this gap and for producing a signal corresponding to the sensed deviation; and means operative in response to a signal from said control means to actuate said driving means for moving the skirt in elevatory movement, whereby the skirt opening can be automatically adjusted in accordance with skull deposition on the furnace mouth to bring the minimum value of the gap between the skirt and the furnace mouth into agreement with said minimum pre-set value.

2. A converter waste gas recovering system as claimed in claim 1 , wherein said control means comprises: a plurality of image processors each associated with a corresponding one of the industrial television cameras for processing the images obtained by the cameras to sense the gap between the furnace mouth and the skirt; a minimum gap selector for selecting a minimum gap value of all the values of the gap between the skirt and the furnace mouth sensed by the image processors; a skirt opening setter for pre-setting the minimum value for the gap between the skirt and the furnace mouth; and an arithmetic unit for calculating the deviation of the value of the gap sensed by the minimum gap selector from the minimum value of the gap set by said skirt opening setter and generating a signal corresponding to the deviation.

3. A converter waste gas recovering system substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.