JPH0245670Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a convection air preheater for recovering exhaust heat from heating furnaces and the like.

(Prior art) This type of air preheater has a large number of tubes installed perpendicular to the flow of exhaust gas in the flue or exhaust gas duct of a steel billet heating furnace, etc. After preheating the fuel by exchanging heat with the fuel, it is used for combustion in a heating furnace to improve combustion efficiency and recover heat.

When this air preheater is installed in the flue, due to its structural constraints, a space larger than the gap between the heat transfer tubes is formed between the tube bundle, the flue wall, and the tube bundles.

These spaces have less resistance to the flow of exhaust gas than the inside of the tube bundle, so when the amount of exhaust gas decreases, such as during low-load operation, the exhaust gas flows into these spaces and becomes a polarized flow, resulting in poor heat exchange. A phenomenon occurs in which water flows out without contributing to the flow.

Therefore, in order to prevent such drift and to perform efficient heat recovery, drift prevention plates are installed in these spaces.

Conventionally, a smooth heat-resistant asbestos board or the like has been used as this drift prevention plate, and it has been installed in these spaces during on-site work after the air preheater main body has been installed in the flue.

(Problem that the invention aims to solve) However, installing such a drift prevention plate requires complicated and difficult on-site work, and since the surface of the drift prevention plate is smooth, it is not possible to completely prevent drift. The problem is that it cannot be obtained.

The present invention was made in view of such problems, and an object of the present invention is to provide an air preheater that can reliably prevent uneven flow of exhaust gas.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides an air preheater equipped with a rectangular tube bundle that is perpendicular to the flow of exhaust gas, with a tube protruding toward the tube bundle at both ends of the tube bundle. , and a drift prevention plate having protrusions parallel to the tubes is disposed close to the tube bundle.

(Example) Next, an example of the present invention will be described with reference to the accompanying drawings.

1 to 3 show an air preheater 1 according to the present invention, in which a plurality of multi-tube heat exchangers are installed inside a flue 2 in a direction perpendicular to the exhaust gas flow indicated by arrow A, This is a well-known method in which the insides of the tubes are interconnected by connecting tubes 3 to allow combustion air to pass in the direction of arrow B, and a tube bundle 6 in which heat transfer tubes 4 are supported by support plates 5 is exposed to the exhaust gas flow path of the flue 2. Has a structure.
In the space X formed between each tube bundle 6 and the flue wall 7, and in the space Y formed between the tube bundles 6 located in parallel, a drift prevention plate 8 and a seal plate 9 are provided.
is installed.

This drift prevention plate 8 is made of a steel plate and processed into a corrugated shape as shown in FIGS. It is arranged close to the tube bundle 6. Moreover, 11 is a protrusion provided in the exhaust gas flow direction. At this time, as shown in FIG. 4, the gap P1 between the heat exchanger tube 4 and the drift prevention plate 8 is
The distance between the heat transfer tubes 4 is substantially the same as the gap P between the heat transfer tubes 4, and the protrusion 10 is disposed so as to be located substantially in the center between the heat transfer tubes 4.

The seal plate 9 is brought into contact with the end of the drift prevention plate 8, and closes the spaces X and Y to prevent exhaust gas from flowing into the space. This seal plate 9 does not necessarily need to close the spaces X and Y, and may be brought into contact only with one end of the drift prevention plate 8 on the most upstream side as long as it can prevent the inflow of exhaust gas.

The material of the drift prevention plate 8 may be SUS310, SUS309S, or SUS30 depending on the atmospheric conditions of the exhaust gas.
4. SS41 or surface-treated steel plate can be used. Note that this drift prevention plate 8 is attached to the support plate 5 by bolting, welding, or the like before installing the main body of the air preheater 1 in the flue 2.

In the tube bundle 6 of the air preheater 1 having the above configuration,
Assuming that exhaust gas from a heating furnace (not shown) flows in the direction of arrow A, the spaces X and Y are closed by the seal plate 9, and since P1≈P, there is no resistance to the inflow into the tube bundle 6. is substantially the same throughout the flow path, and the exhaust gas flows uniformly into the tube bundle 6. In addition, since a flow path similar to the inside of the tube bundle 6 is formed between the drift prevention plate 8 and the heat exchanger tubes 4 by the protrusions 10 of the drift prevention plate 8, the heat exchanger tubes 4 near the drift prevention plate 8 are The heat transfer performance does not deteriorate, and they contribute to heat exchange in the same way as the heat transfer tubes 4 inside the tube bundle 6. Therefore, even if the amount of exhaust gas decreases during low operation, no drift occurs and efficient heat recovery can be performed.

Further, the drift prevention plate 8 expands due to the heat of the exhaust gas, but in this case, if the drift prevention plate 8 is processed into a corrugated shape as shown in FIGS. 5 to 7, this thermal expansion can be absorbed effectively.

In addition, the shape of the corrugate shown in the figure shows an example, and is not limited to this.
For example, as shown in FIG. 8, a plate-shaped one may be attached, and the optimum shape is selected by considering the structure of the air preheater 1, the flow of exhaust gas, the temperature, etc.

In addition, since the air preheater of the above embodiment was of a type in which a plurality of tube bundles were arranged in two rows in a direction perpendicular to the exhaust gas flow, a seal plate was required in the space Y formed between the tube bundles. However, if it consists of one row or one tube bundle, it goes without saying that a sealing plate is required only in the space X formed between the tube bundle and the flue wall.

Furthermore, in the embodiment described above, a seal plate is attached to the end of the drift prevention plate, but the flow path between the drift prevention plate and the opposing flue wall or other drift prevention plate is closed to the exhaust gas flow. If there is no substantial effect, such a seal plate is not required.

(Effect of the invention) As is clear from the above explanation, according to the present invention, the unbalanced flow prevention plates having protrusions are arranged near both sides of the tube bundle, so that the space between the tube bundle and the unbalanced flow prevention plates is reduced. Resistance occurs in the flow of exhaust gas in the tube bundle, which equalizes the flow of exhaust gas and prevents uneven flow, and at the same time, a flow path similar to that in the tube bundle is formed between the ridges provided on the uneven flow prevention plate and the heat transfer tubes. , the heat transfer performance of the heat transfer tubes close to the drift prevention plate does not deteriorate.

For this reason, even when the heating furnace is operating at low
The air preheater of the present invention allows efficient heat recovery.

Further, since the drift prevention plate can be attached before installing the air preheater in the flue, there is no need for complicated and difficult installation work inside the flue.

Furthermore, if the drift prevention plate is made into a corrugated shape,
It has the effect of absorbing deformation caused by exhaust gas heat.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view taken along the - line in Fig. 2, Fig. 2 is a side view showing the installation state of the air preheater according to the present invention, Fig. 3 is its front view, and Fig. 4 is a prevention of drifting. FIG. 5 is a plan view of the drift prevention plate, FIG. 6 is a sectional view taken along the - line in FIG. 5, and FIG. 7 is a sectional view taken along the - line in FIG. 5. , FIG. 8 is a cross-sectional view showing another installation state of the drift prevention plate. 1... Air preheater, 2... Flue, 6... Tube bundle,
7... Flue wall, 8... Straight flow prevention plate, 10... Projection, X, Y... Space.

Claims (1)

[Claims for Utility Model Registration] (1) In an air preheater equipped with a rectangular tube bundle orthogonal to the exhaust gas flow, protrusions are provided on both sides of the tube bundle, protruding toward the tube bundle and parallel to the tube. An air preheater characterized in that a drift prevention plate having a bias current prevention plate is disposed close to a tube bundle. (2) The air preheater according to claim 1, wherein the drift prevention plate has a corrugated shape.