JPH0231314B2 - BUNRIGATAHIITOPAIPUSHIKIKUKYONETSUKI - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an air preheater that preheats air using a high-temperature fluid such as waste gas as a heat source, and particularly relates to an evaporator tube and a condensation tube of a heat pipe structure arranged separately from each other. This invention relates to a heat pipe type air preheater in which the air preheater is connected through a steam communication pipe and a liquid communication pipe.

Prior Art This type of air preheater is, for example,
This is as described in Publication No. 130967, and as shown in FIG. 4, a plurality of evaporation tubes 1 having a heat pipe structure are connected by an upper header 2 and a lower header 3. An evaporation tube group 4 is disposed in a high-temperature waste gas flow path 5, and a condensation tube group 9 is formed by connecting a plurality of condensation tubes 6 having a heat pipe structure with an upper header 7 and a lower header 8. A flow path 1 for air to be heated and heated at a position higher than the evaporation tube group 4
0, and these evaporator tube group 4 and condensation tube group 9
The upper headers 2 and 7 are connected to each other through a steam communication pipe 11, while the lower headers 3 and 7 are connected to each other through a steam communication pipe 11.
8 are communicated with each other through a vapor-liquid communication pipe 12. Gas vent pipe 13 for further exhausting non-condensable gas
is vertically installed in communication with the lower header 8 of the condensing tube group 9. Then, a working fluid 14 such as water is introduced into the loop constructed in this manner.
This is evaporated in the evaporation tube 1 by the heat of the waste gas, and the vapor flows into the condensation tube 6 via the upper header 2 and the steam communication tube 11, where it is By giving heat to the air and condensing and liquefying it, the working fluid 14 transports heat as latent heat due to its state change, and the condensed and liquefied working fluid 14 is transferred to the lower header 8 in the condensing tube group 9.
The liquid is then refluxed to the evaporation tube group 4 via the liquid communication tube 12.
Therefore, as the working fluid 14 evaporates and condenses as described above and circulates continuously,
The air is heated and heated by the heat contained in the waste gas. In addition, non-condensable gases such as _H2 generated during operation are
The gas is exhausted from the gas vent pipe 13.

However, in the air preheater configured as described above, since the evaporation tube group 4 on the heat input side and the condensation tube group 9 on the heat output side are separated, the positions of each can be set arbitrarily, and the As a result, duct routing can be simplified and costs can be reduced accordingly, making it effective for large air preheaters and waste heat recovery equipment.

Problems to be Solved by the Invention The above-mentioned separate air preheater is particularly advantageous when used in a water-type, large-capacity air preheater, as it simplifies the duct routing, but it does not require large size. Due to demands from the viewpoint of strength and cost, carbon steel materials are used as structural materials, and in addition to being inexpensive, they have the advantage of increasing the maximum amount of heat transport as much as possible. Generally, water having a large amount of water is used as the working fluid 14. However, when carbon steel is used as the structural material and water is used as the working fluid, the two react during operation and generate non-condensable _H2 gas, which suppresses the evaporation and condensation of the working fluid. , a problem arises in which heat transport properties deteriorate. Therefore, in the past, a gas vent pipe 13 was installed in the lower header 8 of the condensing pipe group 9 where the flow rate of evaporation was the slowest.
are vertically arranged in communication with each other, and the non-condensable gas separated from the working fluid is collected in the gas vent pipe 13 and exhausted at regular intervals. However, since non-condensable gas has a characteristic of gathering at the top, the above-mentioned configuration has a problem in that the non-condensable gas cannot be completely separated and collected in the gas vent pipe 13.

Furthermore, in the conventional air preheater, the headers 2 and 7 are
Each connecting pipe 1 connects each other and lower headers 3 and 8
Since the connecting pipes 1 and 12 are configured to be connected, even if the routing of the waste gas duct and the air duct can be simplified, there is a problem in that the routing of the respective communication pipes 11 and 12 is complicated.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a separate heat pipe type air preheater that can completely exhaust non-condensable gas and has a simple configuration.

Means for Solving the Problems In order to achieve the above object, the present invention provides an evaporation communication pipe and a liquid communication pipe between the upper header of the evaporation pipe and the lower header of the condensation pipe, and loops are provided here. This structure is characterized by a gas vent valve provided in the upper header of the condensing pipe. More specifically, in the present invention, a plurality of evaporation tubes are arranged in a high temperature fluid flow path with one end elevated, and each end of the evaporation tube is connected to an upper header and a lower header. In addition, a plurality of condensing tubes are arranged with their ends raised in the flow path of the air to be preheated, and each end of the condensing tubes is connected to each other by an upper header and a lower header. Furthermore, the evaporation pipe and the condensation pipe are communicated with each other by a vapor communication pipe and a liquid communication pipe, and heat transport is carried out as latent heat in the flow path formed by the evaporation pipe and the condensation pipe and each communication pipe. In an air preheater having a structure in which a working fluid made of a condensable fluid is sealed, an upper header of an evaporation pipe and a lower header of a condensation pipe are communicated with each other by the evaporation connecting pipe through which working fluid vapor flows. , the liquid communication pipe for distributing and refluxing the liquid-phase working fluid to each evaporation pipe is formed to have a smaller diameter than the evaporation communication pipe, and the liquid communication pipe is connected to the lower header of the condensation pipe, and The present invention is characterized in that a gas vent valve that is inserted into and opened inside the evaporation pipe and for exhausting non-condensable gas is attached to the upper header of the condensation pipe. In addition, the present invention is configured such that a gas-liquid separation tube protruding into the lower header is provided concentrically at the lower end of the condensing pipe to avoid interference between the liquid flow and the vapor flow at the connection between the condensing pipe and the lower header. This is what I did.

Function: Therefore, in the air preheater of the present invention, the working fluid is evaporated and evaporated by heat input from the outside inside the evaporation tube.
The vapor is vaporized, passes through the upper header and the lower header of the condensing pipe, and reaches each condensing pipe, where it imparts heat to the outside air and condenses and liquefies the working fluid. The liquid phase working fluid flows down to the lower header due to its own weight,
The liquid is then distributed and supplied to each evaporation tube via the liquid communication tube. In that case, the non-condensable gases generated during operation are
It rises inside the condensing tube together with the working fluid vapor, but
The working fluid is separated from the working fluid by condensation and liquefaction, and as a result, the non-condensable gas collects at the upper end of the condensing tube, so by periodically opening the gas vent valve, the non-condensable gas in the system can be removed. can be completely exhausted. In addition, since the structure is such that a loop is formed between the upper header of the evaporation tube and the lower header of the condensation tube by each communication tube, these headers are arranged close to each other. The overall structure is simplified. Further, by providing the gas-liquid separation cylinder, there is no interference between the working fluid liquid and the working fluid vapor at the boundary between the condensing pipe and the lower header, and the flow of both is smoothed.

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing the principle of an embodiment of the present invention. First, the structure of the evaporator tube group 15 will be explained. A plurality of evaporator tubes 16 consisting of finch tubes have wicks (not shown in the figure) on their inner surfaces. It has a heat pipe structure in which the non-condensable gas is exhausted and one end of the heat pipe is connected to the upper header 17, and the other end of the evaporator pipe 16 is connected to the lower header 18. Thus, they are connected to each other, and the upper header 17 is connected to the lower header 18.
The evaporator tube 16 is installed higher than the high temperature waste gas flow path 19, and at least the evaporation pipe 16 is located in the high temperature waste gas flow path 19.

Furthermore, the configuration of the condensing tube group 20 will be explained as follows.
The condensing tube group 20 has almost the same configuration as the former evaporation tube group 15, and the plurality of condensing tubes 21 made of finch tubes have a wick (not shown) on the inner surface.
It has a heat pipe structure in which non-condensable gas is exhausted and one end of the condensing pipe 21 is connected to the other by an upper header 22, and the other end of the condensing pipe 21 is connected to a lower header 23. They are connected to each other, and are installed so that the upper header 22 side is higher and the condensing pipe 21 is located in the air flow path 24.

A steam communication pipe 25 for guiding the vapor generated in the evaporator tube group 15 to the condensing tube group 20 is connected to one end of the upper header 17 of the evaporator tube group 15,
The other end of the steam communication pipe 25 is connected to the condensing pipe group 20.
It is connected to one end of the lower header 23 at. Further, a liquid communication pipe 26 for returning the working fluid generated in the condensation pipe group 20 to the evaporation pipe group 15 is formed to have a smaller diameter than the vapor communication pipe 25. It is connected to the other end of the header 23 and inserted into the upper header 17 of the evaporator tube group 15 along its axial direction, and the portion inserted into the upper header 17 has the same number as the evaporator tubes 16. The branched portion is inserted into each evaporation tube 16 and opened. That is, the working fluid is configured to be directly and individually refluxed into each evaporation tube 16 through the liquid communication tube 26. Note that in order to flow the working fluid along the inner circumferential surface of the evaporator tubes 16, at least the evaporator tube group 15
is preferably inclined at an angle of about 5° to 90° with respect to the horizontal plane.

Further, the upper header 22 in the condensing tube group 20
A gas vent valve 27 is attached to the. Further, in the sealed pipe line consisting of the evaporation tube group 15, the condensation tube group 20, and the communication tubes 25 and 26 described above, a condensable fluid such as water is stored as a working fluid while non-condensable gas such as air is exhausted. It is enclosed as.

In the above-described configuration, the liquid-phase working fluid generated in the condensing pipe 21 drips into the lower header 23 at its lower end, and the gas-phase working fluid flows into the boundary corner between the lower header 23 and the condensing pipe 21. The liquid flows along the boundary and flows into the condensing pipe 21, and therefore, gas-liquid interference is most likely to occur at this boundary corner. Therefore, in the above-mentioned apparatus, a gas-liquid separation tube 28 is provided at the lower end of the condensing tube 21, as shown in FIGS. 2 and 3. That is, the gas-liquid separation column 28 is the condensing tube 21
It is a short cylindrical member with a smaller diameter, and is concentrically attached to the lower end inside the condensing tube 21 by a support plate 29 so that the lower end protrudes slightly above the center of the lower header 23. Therefore, the inner peripheral side of the gas-liquid separation cylinder 28 is a vapor flow path, and the outer peripheral side is a liquid flow path.

To heat and raise the temperature of air using the air preheater, waste gas is passed through the high-temperature waste gas passage 19, and air to be heated and heated is made to flow through the air passage 24. At the beginning of the heat input from the high-temperature waste gas, the liquid-phase working fluid descends to the bottom of the evaporator tube group 15, but the liquid-phase working fluid gradually evaporates due to the heat input. The steam passes through the upper header 17 and the steam communication pipe 25 and reaches the condensing pipe group 20, where it is absorbed by the air in the air flow path 24 and condenses and liquefies. The liquid phase working fluid thus generated is transferred to the condensing pipe 2
1 flows down to the lower header 23 and then returns to the evaporator tube group 15 side via the liquid communication pipe 26, and the liquid phase is supplied to each evaporation pipe 16 by the branch portion on the tip side of the liquid communication pipe 26. Working fluid is distributed and supplied.

In a state where such circulating flow of the working fluid is occurring, the working fluid vapor V
As shown in FIG.
The liquid-phase working fluid L flowing down along the inner surface of the gas-liquid separation cylinder 28 flows into the lower header 23 through the outside of the gas-liquid separation cylinder 28 . Therefore, since gas-liquid interference is prevented, the working fluids in the gas phase and liquid phase flow smoothly, improving heat transport characteristics.

The liquid-phase working fluid supplied as described above is evaporated again by heat input from the outside, and the condensing tube group 20
transports heat to the side.

Therefore, in the above air preheater, evaporator tube group 1
5 and the condenser tube group 20 while repeatedly evaporating and condensing the working fluid, the air is heated and heated by the heat of the exhaust gas. If non-condensable gas is generated in the above-mentioned sealed pipe while the working fluid circulates in this way, the non-condensable gas is transferred from the evaporation tube group 15 side to the condensation tube group 20 together with the working fluid vapor. However, inside the condensing pipe group 21, the working fluid vapor radiates heat and condenses and liquefies, so the non-condensable gas is completely separated from the working fluid and flows to the upper header 2 of the condensing pipe group 20.
It accumulates to 2. Therefore, the gas vent valve 2 is periodically
7, it is possible to completely exhaust the non-condensable gas in the sealed pipe line constituted by the evaporation tube group 15, the condensation tube group 20, and the like.

Effects of the Invention As is clear from the above description, according to the present invention, the upper header of the evaporating tube group and the lower header of the condensing tube group are communicated with each other through a vapor communication pipe and a liquid communication pipe, and a loop structure is formed here. Since a gas vent valve is provided at the upper header of the condensing tube group, non-condensable gas generated during operation is removed by the working fluid vapor condensing and liquefying inside the condensing tube. The non-condensable gases can be completely and easily vented by periodically opening the vent valve. Further, in this invention, since a loop structure is formed in which the upper header of the evaporating tube group and the lower header of the condensing tube group are communicated with each other through the vapor communication pipe and the liquid communication pipe, it is possible that these headers are close to each other. As a result, each communication pipe can be short, and therefore, it is easy to route the pipes, and the overall structure can be simplified. Furthermore, since a gas-liquid separation tube is provided at the boundary between the condensing pipe and the lower header below it, interference between the upward flow of working fluid vapor and the downward flow of working fluid liquid flow is avoided, and the flow of each is smoothed. , and as a result, the heat transport properties can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the principle of an embodiment of the present invention, FIG. 2 is a detailed sectional view of the part shown in FIG. 1, and FIG.
The figure is a view taken along the - line in FIG. 2, and FIG. 4 is a schematic diagram showing the principle of an example of a conventional separated heat pipe type air preheater. 15... Evaporation tube group, 16... Evaporation tube, 17,2
2... Upper header, 18, 23... Lower header,
19... High temperature waste gas flow path, 20... Condensing pipe group, 2
DESCRIPTION OF SYMBOLS 1... Condensation pipe, 23... Lower header, 24... Air flow path, 25... Steam communication pipe, 26... Liquid communication pipe, 27... Gas vent valve, 28... Gas-liquid separation cylinder.

Claims (1)

[Scope of Claims] 1. A plurality of evaporation tubes are arranged in a high-temperature fluid flow path with one end elevated, and each end of the evaporation tubes is connected by an upper header and a lower header, respectively. In addition, a plurality of condensing tubes are arranged in the flow path of the air to be preheated with their ends raised high, and each end of the condensing tubes is connected by an upper header and a lower header, and The evaporation pipe and the condensation pipe are connected to each other by a vapor communication pipe and a liquid communication pipe, and the condensation property is such that heat is transferred as latent heat into the flow path formed by the evaporation pipe and the condensation pipe and each communication pipe. In an air preheater configured to contain a working fluid consisting of a fluid,
The upper header of the evaporation tube and the lower header of the condensation tube are
The liquid communication pipe is connected by the vapor communication pipe through which the working fluid vapor flows, and the liquid communication pipe for distributing and refluxing the liquid phase working fluid to each evaporation pipe is formed to have a smaller diameter than the evaporation communication pipe, and The liquid communication pipe is connected to the lower header of the condensing pipe and inserted into and opened inside each evaporation pipe, and a gas vent valve for exhausting non-condensable gas is attached to the upper header of the condensing pipe. A separate heat pipe type air preheater characterized by: 2 A short cylindrical gas-liquid separation cylinder is installed at the lower end of the condensing pipe so that the outer circumferential side is a liquid flow path and the inner circumferential side is an evaporation flow path, and the lower end of the cylinder is protruded into the lower header. The separated heat pipe type air preheater according to claim 1, wherein the separated heat pipe type air preheater is arranged concentrically.