JP2000046413A - Exhaust gas waste heat recovery heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover waste heat from exhaust gas involving a large quantity of water, and hence improve a heat transfer coefficient of a heat transfer surface in a heat exchanger and further suppress a corrosion phenomenon of a heat transfer pipe. SOLUTION: An exhaust gas waste heat recovery heat exchanger comprises a trunk structure 1 including on an upper portion thereof an exhaust gas exhaust outlet 8 communicated with a flue, including therein heat exchange heat transfer pipes 2, 2... and a water droplet removal filter 4, and including in a bottom thereof a porous plate 3, and comprises an outer trunk structure 1a including a bottom thereof communicated with the trunk structure 1 and including in a side thereof an exhaust air stream inlet 6 communicated with a boiler. In the heat exchanger, a water pool layer is formed in the trunk structure 1 and in a bottom layer portion of the outer trunk structure 5, and the water is pushed up to the heat exchange heat transfer pipes 2, 2... with the aid of exhaust gas to form a water fluidized layer. Further, a bypass pipe 8 is coupled with an upper portion of the outer trunk structure 1a for directly feeding part of the exhaust gas flowing from the exhaust air stream inlet 6 to the exhaust gas exhaust outlet 8, and further for joining high temperature exhaust gas to the exhaust gas brought into a water saturated state after passage through the water fluid layer and the water droplet removal filter 4, and reheating those gases and feeding them to the flue.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste heat recovery heat exchanger for efficiently recovering waste heat from exhaust gas containing a large amount of water discharged from a boiler using city gas.

[0002]

2. Description of the Related Art A heat exchanger generally used in the prior art is characterized in that when acidic water containing a chlorine component is present in exhaust gas, the acidic water is changed by the state change of the heat exchanger. There has been a problem that the heat transfer surface repeatedly repeats condensation and concentration by drying to cause a corrosion phenomenon. On the other hand, even in the conventional heat exchanger for recovering waste heat of boiler exhaust gas, there is a problem that corrosive chlorine components contained in the exhaust gas condense on the heat transfer surface of the heat exchanger and cause a corrosion phenomenon. When any of the conventionally used heat exchangers is applied to a boiler using city gas, a large amount of chlorine components and acidic water are contained in the exhaust gas, so, of course, general steel pipes, Even a heat transfer tube using a stainless steel tube has a problem that a severe corrosion phenomenon appears.

[0003] Further, since many of the conventional heat exchangers are configured so that the exhaust gas passes directly between the heat transfer tubes, the heat transfer coefficient between the heat transfer surfaces is low, and the heat exchange efficiency is increased. There was a problem that the heat transfer surface of the heat exchanger had to be formed larger.

In order to solve the above-mentioned conventional problems, the present invention has a high heat transfer coefficient on the heat transfer surface, and furthermore, even if the exhaust gas contains a chlorine component and an acidic water, the heat transfer tube has a corrosion phenomenon. It is intended to provide a waste heat recovery heat exchanger that does not occur.

[0005]

In order to solve the problem, a heat exchanger for waste heat recovery has a large number of heat exchange heat transfer tubes disposed in an exhaust gas flow path of the heat exchanger for waste heat recovery. A puddle layer is provided downstream of the heat transfer tube layer, and the water in the water puddle layer is caused to flow into the heat transfer tube layer by the pressure of the exhaust gas to form a water fluidized bed in which water flows between the heat exchange heat transfer tubes. It is characterized by the following configuration.

[0006] For example, a body having an exhaust gas exhaust port at the upper portion provided with an exhaust gas outlet, a heat exchange heat transfer tube and a water droplet removing layer disposed downstream thereof, and a perforated plate provided at the bottom surface, In a configuration consisting of an outer body having a body and a bottom communicating with each other and having an exhaust inlet on a side, a puddle layer is formed on the body and a bottom layer of the outer body, and water is collected by exhaust gas flowing from the exhaust inlet. The water in the layer may be pushed up between the heat exchange heat transfer tubes via the perforated plate to form a water fluidized bed in which water flows between the heat exchange heat transfer tubes. In the above configuration, if the bottom communication portion of the outer body is formed in an arc shape, it is possible to more efficiently and smoothly push up water by the exhaust gas.

[0007] According to the waste heat recovery heat exchanger having such a configuration, the heat exchange heat transfer tube, that is, the heat transfer surface can be constantly immersed in water while the heat exchanger is operating. Even if a chlorine component and an acidic moisture are contained therein, the concentration of the chlorine component and the acidic moisture can be prevented, and the corrosion phenomenon of the heat transfer tube can be prevented, so that the life of the heat exchanger can be greatly extended. . Further, by forming the water fluidized bed between the heat exchange heat transfer tubes, the heat transfer coefficient between the water fluidized bed and the heat exchange heat transfer tubes can be significantly increased.
Furthermore, since the water contained in the exhaust gas is cooled when passing through the water fluidized bed and condensed, not only the sensible heat of the exhaust gas but also a large amount of latent heat can be recovered, and the heat exchange efficiency is significantly increased. be able to. Thus, the heat exchange efficiency can be increased without increasing the heat transfer area, and the heat exchanger can be downsized. Also, the material of the heat exchange heat transfer tube can be made sufficient by using a normal steel tube without using an uneconomical pin tube.

In the above structure, the exhaust gas flow path is branched into two systems, and the water fluidized bed is formed in one system.
By connecting another one system to the downstream of the water fluidized bed in the one system, it is possible to configure so that high-temperature exhaust gas merges with cooled exhaust gas passing through the water fluidized bed. For example, a bypass pipe connected to the exhaust gas outlet is connected to the upper part of the outer body, and a part of the exhaust gas flowing into the outer body from the exhaust inlet is guided to the exhaust gas outlet through the bypass pipe, and a water fluidized bed is formed. And it can be configured to merge with the exhaust gas that has passed through the water droplet removal layer. According to this structure, the high-temperature exhaust gas is combined with the exhaust gas that has been deprived of moisture and heat by passing through the water fluidized bed and the water droplet removal layer to be in a moisture-saturated state, and the exhaust gas in the moisture-saturated state is reheated. This can prevent the water condensation phenomenon due to the cooling of the exhaust gas in the flue after the exhaust gas outlet, and can increase the boiler combustion efficiency because the exhaust gas is smoothed.

Further, in the above configuration, the water supply pipe and the drain pipe provided with the automatic adjustment valve on the side surface of the body can be connected so that the height of the fluidized bed can be maintained constant. With this configuration, not only can the heat transfer surface be immersed in water more reliably, but also there is no accumulation of more water than necessary, so that the heat exchange efficiency can be further improved and stabilized.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

The heat exchanger for recovering waste heat shown in FIG. 1 comprises a square body 1 and an outer body 1a.
Is provided with an exhaust gas outlet 8 leading to the flue at the upper end thereof, a perforated plate 3 provided at the bottom, a water droplet removing filter 4 provided at an upper inner portion, and a plurality of heat exchange transfer devices provided at an inner lower portion. The heat pipes 2, 2,... Are arranged, and a water supply pipe 7a with an automatic adjustment valve 7 and a drain pipe 10 are connected at an intermediate position between the water drop removing filter 4 and the heat exchange heat transfer pipe 2 on the side surface. I have.

The outer body 1a is disposed so as to surround at least the bottom surface of the square body 1 and form an exhaust gas guide passage 5 on one side of the square body 1.
Is connected to a bypass pipe 9 communicating with the exhaust gas discharge port 8, an exhaust inlet 6 communicating with a boiler using city gas is provided on a side surface of the outer body 1a, and a bottom surface 1b of the outer body 1a is The perforated plate 3 is formed as an inclined surface which is inclined downward from the other end of the perforated plate 3 toward one side so as to form the exhaust gas guide passage 5a. It communicates with the bottom of the body 1. The one end of the bottom surface 1b, that is, the connecting portion between the side surface and the bottom surface 1b may be formed in an arcuate shape as shown in FIG.

[0013] In the heat exchanger for recovering waste heat configured as described above,
When an appropriate amount of water is supplied to the rectangular body 1 through the water supply pipe 7a in the boiler operation stop state, water accumulates in the bottom layers of the exhaust gas guide passages 5, 5a and the rectangular body 1 through the perforated plate 3, and the water accumulation layer To form When the boiler is operated in this state, the water in the puddle layer is pushed up by the pressure of the exhaust gas flowing into the outer body 1 a through the exhaust inlet 6, flows into the square body 1 through the perforated plate 3, and is heated. A water fluidized bed is formed between the exchange heat transfer tubes 2, 2,. At this time, the height of the water fluidized bed can be constantly maintained by adjusting the amount of water supplied by the automatic control valve 7 installed in the water supply pipe 7a and the amount of drainage in the drain pipe 10. As shown in FIG. 3, the side surface and the bottom surface 1b of the square outer body 1a
When the connecting portion is formed in an arc shape, the water in the exhaust gas guide passage 5 can be effectively caused to flow into the rectangular body 1.

As described above, since the heat exchange heat transfer tubes 2, 2,..., That is, the heat transfer surfaces can always be immersed in water while the heat exchanger is operating, the corrosion phenomenon of the heat transfer tubes due to the concentration of acidic moisture. Can be prevented, and the life of the heat exchanger can be greatly extended. Further, by forming a water fluidized bed between the heat exchange heat transfer tubes 2, 2,..., The heat transfer coefficient between the water fluidized bed and the heat exchange heat transfer tubes 2 becomes extremely high, so that heat transfer is significantly promoted. can do.

Next, the operation of the heat exchanger for waste heat recovery having the above-described configuration will be described. When the boiler is operated, high-temperature exhaust gas containing a large amount of water flows into the outer body 1a through the exhaust inlet 6, and a part of the exhaust gas flows through the exhaust gas guide passages 5, 5a. And the exhaust gas and the fluidized bed rapidly reach thermal equilibrium due to rapid heat transfer in direct contact with water in the fluidized bed. In this process, the water contained in the exhaust gas is condensed in the water fluidized bed, so that the water fluidized bed effectively collects a large amount of latent heat together with the sensible heat of the exhaust gas. The exhaust gas that has been deprived of moisture and heat by passing through the water fluidized bed in this manner and then in a water-saturated state is then passed through a water droplet removing filter 4 to further remove moisture, and is then supplied to an exhaust gas outlet 8. Inflow.

On the other hand, the remaining exhaust gas flowing into the outer body 1a through the exhaust inlet 6, ie, a part of the high-temperature exhaust gas, flows into the exhaust gas outlet 8 through the bypass pipe 9, where the water fluidized bed and It passes through the water droplet removal filter 4 and merges with the exhaust gas that has been saturated with water. Therefore, the exhaust gas in the moisture-saturated state is reheated, and in the flue after the exhaust gas outlet 8, the condensation phenomenon of the moisture due to the cooling of the exhaust gas can be prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a waste heat recovery heat exchanger as one embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view of a main part showing a modification of the heat exchanger for waste heat recovery of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Square body 1a Square outer body 1b Bottom surface 2 Heat exchange heat transfer tube 3 Perforated plate 4 Water drop removal filter 5, 5a Exhaust gas guide passage 6 Exhaust inlet 7 Automatic control valve 7a Water supply pipe 8 Exhaust gas outlet 9 Bypass pipe 10 Drain pipe

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[Procedure amendment]

[Submission date] September 3, 1999 (1999.9.3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

In order to solve the problem, a heat exchanger for waste heat recovery has a large number of heat exchange heat transfer tubes disposed in an exhaust gas flow path of the heat exchanger for waste heat recovery. A puddle layer is disposed upstream of the heat transfer tube layer, and the water in the puddle layer is caused to flow into the heat transfer tube layer by the pressure of the exhaust gas so as to form a water fluidized bed in which water flows between the heat exchange heat transfer tubes. It is characterized by the following configuration.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor San Il-Paak, Republic of Korea Daejeon-shi, Theok, Walpillion-Dong, 286, Han-Almua, Part 108-907 (72) Inventor Kyung Bin Choi, Republic of Korea -Sun-K, U-R-D-N, 99, Hanbitapart 128-505 (72) Inventor Yan Jin-Ha, Republic of Korea Daejeon-Shi, U-S-N-K, U-R-D-N, 99, Han-bit-Apart 102- No. 1603 (72) Inventor Ki-ho Park South Korea Daejeon-shi, Yousun-k, Ureng-dong, 99, Hanbitzapart 126-305 (72) Inventor Chang Bo-ko South Korea Daejeon-shi, Yu Sunk, Uren-Don, 99, Hanbituapa Preparative No. 129-301 (72) inventor Joon gum Kim Korea Daejeon - sheet, Yoo - Sun - click, Won'nae - Don, 383, Jiang Apartment 105-307 No. F term (Reference) 3L034 BA25

Claims (6)

[Claims] 1. A puddle layer is disposed downstream of a heat transfer tube layer provided with a plurality of heat exchange heat transfer tubes in an exhaust gas flow path of an exhaust gas waste heat recovery heat exchanger. An exhaust gas waste heat recovery heat exchanger having a configuration in which water in a puddle layer flows into a heat transfer tube layer to form a water fluidized bed in which water flows between heat exchange heat transfer tubes. 2. An exhaust gas distribution path is branched into two systems,
The above-mentioned water fluidized bed is formed in a system, and another one system is connected downstream of the water fluidized bed in the one system, so that the high-temperature exhaust gas merges with the cooled exhaust gas passing through the water fluidized bed. The heat exchanger for exhaust gas waste heat recovery according to claim 1, wherein the heat exchanger is configured as follows. 3. A fuselage having an exhaust gas discharge port at the upper part, which is connected to a flue, a heat exchange heat transfer tube and a water drop removing layer disposed downstream thereof, and a perforated plate disposed at the bottom. In a configuration comprising an outer body having a body and a bottom communicating with each other and an exhaust inlet provided on a side portion, a puddle layer is formed on the body and a bottom layer of the outer body, and water is collected by exhaust gas flowing from the exhaust inlet. An exhaust gas waste heat recovery heat exchanger configured to push up water in a bed between heat exchange heat transfer tubes via a perforated plate to form a water fluidized bed in which water flows between the heat exchange heat transfer tubes. 4. The heat exchanger for exhaust gas waste heat recovery according to claim 3, wherein the bottom communication portion of the outer body is formed in an arc shape. 5. A bypass pipe connected to an exhaust gas outlet is connected to an upper part of the outer body, and a part of the exhaust gas flowing into the outer body from the exhaust inlet is guided to the exhaust gas outlet through the bypass pipe. The heat exchanger for exhaust gas waste heat recovery according to claim 3 or 4, wherein the heat exchanger is configured to merge with the exhaust gas passing through the water fluidized bed and the water droplet removal layer. 6. A water supply pipe provided with an automatic control valve on a side surface of a body and a drain pipe, so that a height of the fluidized bed can be maintained constant. The heat exchanger for exhaust gas waste heat recovery according to the above item.