JPH09250733A - Steel stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dew condensation in an inner tube by providing a space inside the inner tube having an outer surface on which a heat retaining material is wound and an inner surface forming a gas duct, lining the space with an inner plate and arranging a pipeline and a blower for supplying dry air to the space below the inner tube. SOLUTION: A supporting point member 52 is fixed to a small beam 51 made of an H shaped steel or the like. An inner tube reinforcing ring 16 is fixed to the outer peripheral position of an inner tube 1 opposed to the supporting point member 52 so as to have a clearance for absorbing thermal expansion from the supporting point member 52 and the ring. Further, an inner plate 12 is fastened to an inner tube 1 by means of bolts 17 in the gas duct side of the inner tube 1. A space a is formed between the inner plate 12 and the inner tube 1 for supplying air from a pipeline. Then, a blower for supplying dry air to the space a through the pipeline is arranged below the inner tube 1. Thus, the dew condensation and corrosion of the inner tube 1 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel chimney used in a corrosive gas atmosphere, and more particularly to a steel chimney having corrosion prevention measures.

[0002]

2. Description of the Related Art A conventional steel chimney is shown in FIG.
As shown in FIG. 3, a steel inner cylinder 1 that guides exhaust gas flowing from an inlet (not shown) to the atmosphere is erected, a heat insulating material 2 is wound around the inner cylinder 1, and the heat insulating material 2 is further attached. It has an external heat insulation structure surrounded by a lagging plate 3.

An outer cylinder 4 serving as a strength member is erected on the outer side of the inner cylinder 1, and the outer cylinder 4 and the inner cylinder 1 are assembled in a frame shape at several places in the height direction. Encased supports 5, 5,
・ Supported by.

Reference numeral 6 is a protective plate for the inner cylinder 1, 7 is a water stop plate for rain water, 8 is a roof floor, 9 is a chimney foundation, 10 is a base plate, and 11 is an anchor bolt.

Generally, the steel chimney is corroded because the corrosive exhaust gas components are condensed on the surface of the inner cylinder 1. In order to prevent the corrosion, a structure that does not allow the condensation should be formed. Therefore, in the above-mentioned steel chimney, the inner surface of the inner cylinder 1 has a corrosive high-temperature exhaust gas such as HCL, SO _X , NO _X, etc.
Even if the inner cylinder 1 is exposed to the atmosphere, the outer surface of the inner cylinder 1 is kept warm to raise the temperature of the inner cylinder 1 itself, thereby preventing dew condensation.

[0006]

However, the above-mentioned conventional steel chimney has the following problems. (1) When the chimney is at rest, rainwater may enter the inner cylinder and cause corrosion, and the exhaust gas conditions may be such that the harmful gas removal equipment is out of order or the water content in the exhaust gas is regulated. Corrosion occurs when the temperature reaches (2) In the refuse incinerator, if the operation such as operating every other day according to the amount of refuse is performed, the chances of transitioning from the dew point range to the dew point range increase, so Corrosion resistance is significantly reduced. Therefore, the smoke passing period is set to be as continuous as possible, and there are restrictions such as avoiding intermittent operation.

As another measure, it is conceivable to mix hot air into the exhaust gas to raise the dew point temperature of the exhaust gas, but it is necessary to send hot air commensurate with the amount of exhaust gas, which is enormous. Since a large amount of heat and a large amount of air are required, there is a problem of high cost.

It is an object of the present invention to prevent the occurrence of dew condensation on the inner cylinder to prevent corrosion regardless of whether the chimney is operating or not operating.

[0009]

[Means for Solving the Problems] The above-mentioned problem is that an inner plate is stretched by arranging a heat insulating material on an outer surface and providing a gap inside an inner cylinder whose inner surface constitutes a flue, and below the inner cylinder. The problem is solved by a steel chimney characterized by arranging a pipe and a blower for allowing dry air to flow into the gap.

According to the above-mentioned means, since the dry air is made to flow into the gap between the inner cylinder and the inner plate from the lower side of the inner cylinder by the pipe and the blower, the outer surface of the inner cylinder is kept warm during the operation of the steel chimney. Therefore, heat dissipation is prevented and the inner surface of the inner cylinder does not come into contact with the exhaust gas, so that no condensation occurs. Also, during the rest of the steel chimney,
Even if rainwater or the like enters, the inner surface of the inner cylinder is dried, so that dew condensation of corrosive gas does not occur.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an elevational sectional view showing a steel chimney according to the present invention. The same parts as in the prior art will be described using the same reference numerals.

In FIG. 1, 1 is an inner cylinder of a steel chimney, 2 is a heat insulating material, 3 is a lagging plate surrounding the heat insulating material 2, and 4 is an outer cylinder.

Reference numeral 5 is a support provided between the outer cylinder 3 and the inner cylinder 1, 6 is an inner cylinder protection steel plate, and 7 is a water stop plate.

According to the present invention, the inner plate 12 is provided on the flue side of the inner cylinder 1.
Are provided in the circumferential direction and the height direction.

Further, one end of the pipe 13 is positioned in a gap (a gap a described later) between the inner cylinder 1 and the inner plate 12,
An air blower 14 is provided in the middle of the pipe 13, and the other end of the pipe 13 removes the humidity of the air to control the temperature of the air preheater 15.
Connect to

When dry air having a pressure equal to or higher than the internal pressure of the inner cylinder 1 is sent into the gap by the blower 14, the exhaust gas does not come into contact with the surface of the inner cylinder 1, so that the inner cylinder 1 is not corroded by the condensation of the exhaust gas.

Further, since the air preheater 15 controls the air temperature, even in a chimney whose exhaust gas temperature exceeds 300 ° C.,
If the temperature of the inner cylinder 1 is lowered by sending air at a temperature lower than that, it is not necessary to use a high temperature resistant material for the inner cylinder 1.

Further, while the chimney is at rest, by generating dry air having a relatively high temperature, the surface temperature of the inner cylinder 1 and the inner plate 12 can be raised to be dried to prevent corrosion.

FIG. 2 is a sectional view taken in the direction of arrow A in FIG. 1, and 4 is a rectangular (also round) outer cylinder, and a support 5 is assembled inside the outer cylinder 4 in a frame shape. It has a structure for supporting the cylinder 1.

The support 5 is constructed by forming large square frames 50 with large beams 5a, 5b, 5c and 5d, and small beams 51 are provided in the four corners of the large frame 50, and supporting point members 52 are fixed to the small beams 51. Has been done.

FIG. 3 is an enlarged sectional view of a portion B of FIG. 1, in which a supporting point member 52 is fixed to a beam 51 made of H-shaped steel or the like. On the other hand, the inner cylinder 1 at the position opposite to the supporting point member 52
An inner cylinder reinforcing ring 16 is fixed to the outer periphery of the above, and is arranged with a gap for absorbing thermal expansion with the supporting point material 52.

Further, on the flue side of the inner cylinder 1, an inner plate 12 is fastened to the inner cylinder 1 with bolts 17. Reference numeral 18 is a nut fixed to the inner cylinder 1, 19 is a washer, and 20 is a tightening nut.

Between the inner plate 12 and the inner cylinder 1, the pipe 1
3 are arranged so as to form a gap a into which the air from 3 flows. The gap a has a thickness of the inner plate 12 of 5 to 5, for example.
If it is about 10 mm, the gap is about 50 mm. Furthermore, the inner plate 12 is provided with an adjacent plate 12 and an expansion allowance b.

Since the inner plate 12 is a segment type, depending on the combination, the inner cylinder 1 can be applied to either a square shape or a round shape.

FIG. 4 is a sectional view taken along the line C in FIG. 3, in which the inner plate 12 is fastened to the inner cylinder 1 by bolts 17 with an expansion allowance a also provided in the circumferential direction of the inner cylinder 1.

Although the present invention has been described with respect to the chimney, it can be applied to a corrosive exhaust gas duct in addition to the chimney.

[0027]

As described above, the present invention prevents corrosion of the inner cylinder surface regardless of whether the steel chimney is in operation or at rest.

Further, since the gap between the inner cylinder and the inner plate may have a small cross-sectional area, the capacity of the blower may be small, and the continuous operation of the entire equipment for preventing the dew condensation of the steel chimney as in the past is unnecessary. The operating cost is low, which is an advantage.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a steel chimney according to the present invention.

FIG. 2 is a sectional view taken in the direction of arrow A in FIG. 1;

3 is a partial B sectional view of FIG.

FIG. 4 is a sectional view taken along arrow C in FIG.

FIG. 5 is a vertical cross-sectional view showing a steel chimney in the prior art.

[Explanation of symbols]

 1 Inner Cylinder 2 Heat Insulating Material 3 Lagging Plate 4 Outer Cylinder 5 Support 50 Large Beam 51 Small Beam 52 Supporting Point Material 6 Inner Cylinder Protective Steel Plate 7 Water Stop Plate 8 Roof Floor 9 Chimney Foundation 10 Base Plate 11 Anchor Bolt 12 Inner Plate 13 Piping 14 Blower 15 Air preheater 16 Inner cylinder reinforcing ring 17 Bolt a Air inflow gap b Expansion allowance

Claims (1)

[Claims] 1. A heat insulating material is wound on an outer surface, and an inner plate is stretched with a gap provided inside the inner cylinder whose inner surface constitutes a flue. Dry air flows into the gap below the inner cylinder. A steel chimney characterized by arranging piping and a blower.