JPH0225035Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention is a water-cooled system that lowers the temperature of high-temperature exhaust gas, especially the exhaust gas from steelmaking electric furnaces, during induction to a temperature that allows suction and dust removal by an exhaust fan. Regarding ducts.

<Prior Art> Electric furnaces for steelmaking generate a large amount of dust such as iron oxide powder and slag powder, which must be sucked up with an exhaust fan and collected with a dust remover. For this reason, it is necessary to lead the high-temperature electric furnace exhaust to the dust remover and at the same time lower the temperature to a level that does not interfere with the operation of the exhaust fan and dust remover, so a water-cooled duct is used as the duct. Although this water cooling duct is cooled by cooling water, it undergoes repeated thermal cycles of over 1,000 degrees and expands and contracts as a result, so expansion and contraction structures are installed in places to absorb this expansion and contraction. .

As shown in FIG. 3, the conventional expandable structure has anchors 5, 5, and 5 anchors on end plates 4, 14 that seal water canals 3, 13 at both ends of inner tubes 1, 11 and outer tubes 2, 12, respectively. 15, and the refractories 6 and 16 held by anchors 5 and 15, respectively, are placed facing each other across a gap 7, and further between the flanges 8 and 18 extending outward from the outer cylinders 2 and 12, respectively. It is hermetically sealed with bellows 9.

<Problem that the invention aims to solve> The inside of the water cooling duct is normally under negative pressure due to suction by the exhaust fan, but when new raw materials are inserted into the furnace or oxygen or deoxidizer is supplied, the pressure inside the water cooling duct is negative. may cause a rapid reaction and result in positive pressure. In addition, in the water cooling duct described above, a large amount of dust tends to accumulate in the space between the bellows 9 and the refractories 6 and 16.

In the conventional expandable structure described above, since the refractories 6 and 16 were not water-cooled, the heat inside the duct was transferred to the bellows 9, which caused the bellows 9 to rise in temperature and break. In addition, the refractories 6 and 16 were likely to fall off, and if this occurred, the bellows 9 would be exposed to high temperatures and be damaged immediately. When such damage occurs, a large amount of accumulated dust is ejected to the outside world when the pressure inside the duct changes to positive pressure.

This idea aims to realize a joint structure that stably maintains airtightness over a long period of time and prevents dust from ejecting to the outside world even when the pressure inside the duct changes to positive.

<Means for Solving the Problems> In this invention, the first and second ducts each consist of an inner cylinder and an outer cylinder that are coaxially arranged, and a terminal member that connects their ends. A water canopy is formed between the cylinders. The first and second ducts are arranged coaxially, and their respective end members directly face each other with a small gap in between. A flange is present on the outer cylinder of the first duct, and an annular support member supported at one end by the flange extends beyond the small gap to the outside of the second duct. This annular support member supports an annular packing at its tip, and the inner surface of this packing contacts the circumferential surface of the outer cylinder of the second duct. A heat-resistant flexible membrane with high airtightness is passed between the front surface of this packing, that is, the surface far from the first duct, and the flange provided on the outer cylinder of the second duct.
This highly airtight heat-resistant flexible membrane uses, for example, heat-resistant seal cloth commercially available under the trade name Kao Wool, highly dense asbestos cloth, metal bellows, or the like.

<Operation> When the first duct and the second duct expand and contract,
The width of the small gap between them changes, and the packing slides on the outer circumferential surface of the outer cylinder of the second duct accordingly. At this time, the highly airtight, heat-resistant, flexible membrane bends freely. A highly airtight, heat-resistant flexible membrane maintains airtightness between the inside and outside of the duct, but this membrane is isolated from the high-temperature gas inside the duct by packing. In addition, since the packing itself is in contact with the low-temperature second duct outer cylinder with a small gap between the ducts, there is little deterioration due to temperature rise, but after long-term use, the packing itself will deteriorate with the second duct. The contact surfaces wear out and create gaps.

Dust generated in the furnace tends to accumulate in the connecting portion of the first and second ducts. The inside of the water cooling duct is normally under negative pressure, but if a sudden reaction occurs in the furnace and the pressure changes to positive, a large amount of accumulated dust will be released if there is no heat-resistant flexible membrane. , ejects into the outside world from gaps created by the wear of the packing. However, since the heat-resistant flexible membrane is provided, even if the pipe pressure becomes positive pressure, such ejection of dust does not occur.

Note that if the annular support member is made separable in advance, it can be easily removed and inspected inside.

<Example> In Figs. 1 and 2, ducts A and B both connect the inner cylinders 1 and 11 and the outer cylinder 12, the water canals 3 and 13 formed between the inner and outer cylinders, and the ends of the outer and outer cylinders. It consists of annular end members 21 and 22 with semicircular arc cross sections. The ducts A and B are coaxially arranged, and the termination members 21 and 22 face each other with a small gap 23 in between.

A flange material 24 with an L-shaped cross section is welded to the outer periphery of the outer cylinder 2 of the duct A, and one wing 25a of an annular support material 25 with a U-shaped cross section is attached to the flange material 24 with a bolt 27 by sandwiching a thin airtight packing 26. Fixed. At the tip of the annular support member 25, that is, the other wing 25b, a thick annular asbestos packing 28 and a seal cloth 29 made of Kao wool are stacked and fixed with bolts 30, and the inner surface of the asbestos packing 28 is attached to the outer cylinder of the duct B. Close to the outer periphery of 12. The other side of the seal cloth 29 is fixed to a flange 31 welded to the outer circumference of the outer cylinder 12 with bolts 32.

In addition, 33 is a reinforcing rib of the annular support member 25, 34
35 is a duct receiver, 36 is a cooling water inflow pipe, and 37 is a cooling water discharge pipe.

In the above-described embodiment, the cooling water is circulated to the tip portions of the ducts A and B that face each other in the small gap 23, and no refractories that easily break off are used, so there are no accidents occurring there. When ducts A and B expand and contract due to thermal cycles, the small gap 23
As the width changes, the packing 28 slides along the outer surface of the outer cylinder 12 of the duct B, and the seal cloth 29 expands and contracts. Since airtightness inside and outside the duct is maintained by the seal cloth 29, even if the packing 28 is worn out and a gap 38 is formed between the packing 28 and the outer cylinder 12, high temperature gas will not flow through the small gap 23. Therefore, the packing 28 is not exposed to high-temperature gas, is located outside the duct B, and is not exposed to thermal radiation, so there is no risk of damage due to heat, and furthermore, the packing 28 is located outside the duct B. The seal cloth 29 is safer against heat, and can prevent dust generated in the furnace from being ejected to the outside world due to its breakage.

<Effects of the invention> As described above, this invention does not use refractories that cannot be cooled and easily break off, does not necessarily require expensive bellows, and does not require packing or refractory material for maintaining airtightness. Since the flexible membrane is not exposed to high temperatures, it is possible to realize an expandable structure for a high-temperature gas duct that operates stably over a long period of time.

[Brief explanation of the drawing]

Figure 1 is an enlarged sectional view of an embodiment of this invention;
The figure is a side view showing the whole of the above embodiment, and FIG. 3 is an enlarged sectional view of a conventional expandable structure. 1 and 11...Inner cylinder, 2 and 12...Outer cylinder, 3
and 13... water mantle, 21 and 22... terminal material, 2
3... Small gap, 24... Flange material, 25... Annular support material, 28... Annular packing, 29... Flexible membrane, 31... Flange, A... First duct,
B...Second duct.

Claims (1)

[Scope of utility model registration request] first and second ducts each having a water cannula between an inner cylinder and an outer cylinder coaxially arranged, the water cannula being sealed by a termination member connected between the ends of the inner and outer cylinders; The above-mentioned terminal members are arranged coaxially with each other facing each other with a small gap, and the annular support member is supported by a flange provided on the outer cylinder of the first duct and extends outward of the second duct. An annular packing whose inner surface contacts the outer peripheral surface of the outer cylinder of the second duct is supported at the tip, and a heat-resistant material with high airtightness is provided between the front surface of the annular packing and the flange provided on the outer cylinder of the second duct. A stretchable structure of a water cooling duct that spans a flexure membrane.