JPH11264677A - Crossflow bayonet heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance heat exchanging performance of a crossflow bayonet heat exchanger operating at high temperature. SOLUTION: A group of bayonet heating tubes 1 each comprising an outer tube 1a having a blind forward end and an inner tube 1b inserted therein is inserted into a heating fluid channel 4 such that the flow direction of a heating fluid 5 intersects the direction of the bayonet heating tube 1 perpendicularly thus constructing a crossflow bayonet heat exchanger. A pair of bayonet heating tube groups 7 are arranged oppositely while alternating the direction of tube row every stage and the forward end 1c of one bayonet heating tube 1 is located close to the base end 1d of the other bayonet heating tube 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bayonet heat exchanger for exchanging heat between a high-temperature heating fluid such as exhaust gas from a gas turbine and a low-temperature fluid to be heated such as air.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view of a conventional crossflow type bayonet heat exchanger. The bayonet heat transfer tube 1 includes an outer tube 1a having a blinded end and an inner tube 1b inserted therein. Reference numeral 2 denotes a bayonet heat transfer tube header, which includes an outer tube header 2a and an inner tube header 2b.
The heated fluid 3 flows into the inner tube 1b from the inner tube header 2b, flows out of the distal end thereof, and flows through the heating fluid flow path 4 while flowing through the gap between the outer tube 1a and the inner tube 1b. 5
And the temperature rises due to heat exchange between them, and flows out through the outer pipe header 2a. Reference numeral 6 denotes a passage wall that forms the heating fluid flow path 4. Contrary to the above, the fluid to be heated 3 flows from the outer pipe header 2a, flows through the gap between the outer pipe 1a and the inner pipe 1b, flows in from the tip of the inner pipe 1b, and flows out of the inner pipe header 2b. Some have been made.

[0003] The bayonet heat exchanger is excellent as a high-temperature heat exchanger using ceramics or the like, since the outer tube 1a and the inner tube 1b are cantilevered, so that they can freely expand and do not generate large thermal stress. ing.

[0004]

The fluid to be heated 3 is the inner tube 1
a, and flows out from the tip of the outer tube 1a and the inner tube 1
The temperature rises while flowing from the front end 1c to the base end 1d through the gap with the base b. Therefore, the temperature difference between the heating fluid 5 and the fluid to be heated 3 is large on the distal end 1c side and small on the proximal end 1a side.
Therefore, the amount of heat transfer on the tip 1c side is larger than that on the base end 1d side, and the temperature of the heating fluid 5 after passing through the tube group 7 of the bayonet heat transfer tube 1 is lower on the tip 1c side and higher on the base end 1d side. .

FIG. 3 is a graph showing the temperature distribution of the heating fluid 5 in the longitudinal direction of the bayonet heat transfer tube. The horizontal axis represents the distance L in the longitudinal direction of the bayonet heat transfer tube, and the vertical axis represents the temperature T. When the heating fluid 5 flows into the heat transfer tube group 7, there is no temperature difference between the tip 1c side and the base end 1d side at the entrance of the first stage tube group 8, but the first stage tube row 8, the second stage tube row 9, the third stage Since all the pipe rows 10 have the same pipe direction, the temperature difference accumulates and increases as it flows down from the first-stage pipe row 8 outlet, the second-stage pipe row 9 outlet, and the third-stage pipe group row 10 outlet.

When the fluid 3 to be heated flows in from the header 2a for the outer tube and flows out from the header 2b for the inner tube, the temperature curve of the heating fluid at the outlet of the heat transfer tube group 7 is opposite to that of the above at the tip 1c side. Although it is high and becomes low on the base end 1d side, the tendency is the same, so a detailed description is omitted.

As described above, if the temperature distribution is deviated while the heating fluid 5 is flowing in the flow path 4, the flow distribution in the flow path 4 becomes uneven due to the difference in the viscous resistance. Heat exchange performance.

The present invention has been devised in view of the above-mentioned problems of the prior art, and reduces the bias of the temperature distribution generated while the heating fluid 5 flows through the flow path 4 to reduce the occurrence of drift. To improve heat exchange performance.

[0009]

To achieve the above object, a cross-flow type bayonet heat exchanger according to the present invention comprises a bayonet heat transfer tube comprising an outer tube having a blinded end and an inner tube inserted therein. Is a cross flow type bayonet heat exchanger in which the flow direction of the heating fluid and the direction of the bayonet heat transfer tube are inserted in the heating fluid flow path so that the directions of the heating fluid are orthogonal to each other. A pair of bayonet heat transfer tube groups are arranged to face each other so that the direction changes alternately for each stage of the tube row, and the tip of one bayonet heat transfer tube is close to the base end of the other bayonet heat transfer tube. It is like that.

Next, the operation of the present invention will be described. A pair of bayonet heat transfer tubes is arranged to face each other so that the direction of the bayonet heat transfer tube row changes alternately in each row of the tube row, and the tip of one bayonet heat transfer tube is close to the base end of the other bayonet heat transfer tube. Therefore, even if a deviation in the temperature distribution of the heating fluid occurs at the outlet of the first row of pipes, the deviation is corrected by the next row of pipes. Since the occurrence and elimination of the deviation are repeated in this manner, there is no deviation in the temperature distribution of the heating fluid at the tube group outlet, and therefore, no deviation occurs. Therefore, the heat exchange performance is improved as compared with the conventional cross-flow type bayonet heat exchanger.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front sectional view of a cross-flow type bayonet heat exchanger of the present invention, and FIG.
FIG. In these figures, the same reference numerals are given to parts common to the conventional cross-flow type bayonet heat exchanger described with reference to FIG.

1 and 5, reference numeral 1 denotes a bayonet heat transfer tube, which comprises an outer tube 1a having a blinded end and an inner tube 1b inserted therein. Reference numeral 2 denotes a bayonet heat transfer tube header, which includes an outer tube header 2a connected to the outer tube 1a and an inner tube header 2b connected to the inner tube 1b. 3 is a fluid to be heated such as air. Reference numeral 4 denotes a heating fluid passage through which a heating fluid 5 such as gas turbine exhaust gas flows. A large number of bayonet heat transfer tubes 1 are connected to the bayonet heat transfer tube header 2 to form a tube group 7 of bayonet heat transfer tubes. Tube group 7
Are inserted into the heating fluid flow path 4 such that the flow direction of the heating fluid 5 and the direction of the bayonet heat transfer tube 1 are orthogonal to each other.

A tube group 7a of the left bayonet heat transfer tube and a tube group 7b of the right bayonet heat transfer tube are arranged to face each other with one tube group 7a inserted into the other tube group 7b. I have. The tube group 7a on the left side includes the first row 11 and the third row.
And a tube group 13b on the right side,
It has a row 12 of rows and a row 14 of rows. Tube row 1
Bayonet heat transfer tubes 1 are arranged in a zigzag manner as shown in FIG. The directions of the bayonet heat transfer tubes 1 forming the first and third stage tube rows 11 and 13 and the directions of the bayonet heat transfer tubes forming the second and fourth stage tube rows 12 and 14 are opposite to each other. Yes, and therefore, the direction of the heat transfer tube row changes alternately for each stage.
The left tube group 7a and the right tube group 7b are inserted deeply into each other, and the tip 1c of the bayonet heat transfer tube 1 of the right tube group 7a and the tip 1 of the bayonet heat transfer tube 1 of the left tube group 7b.
c is close to the base end 1d of each of the other tube groups 7a and 7b.

Next, the operation of the present embodiment will be described. The directions of the bayonet heat transfer tubes 1 are opposite in the first-stage tube row 11, the third-stage tube line 13, the second-stage tube line 12, and the fourth-stage tube line 14. Therefore, as shown in FIG. 4, even if the temperature distribution of the heating fluid 5 is biased at the outlet of the first-stage tube row 11,
The deviation in the temperature distribution at the outlet is corrected by the correction in the second-stage tube row 12, and the deviation is eliminated. As described above, since the occurrence and the elimination of the temperature distribution deviation are sequentially repeated in the tube rows at each stage, there is no deviation in the temperature distribution at the final outlet of the tube group 7, and therefore, no deviation occurs. Therefore, the performance of the heat exchanger is improved as compared with the conventional cross-flow type bayonet heat exchanger shown in FIG.

The present invention is not limited to the embodiment described above, and various changes can be made without departing from the gist of the invention.

[0016]

As described above, the crossflow type bayonet heat exchanger of the present invention is arranged so that the direction of the bayonet heat transfer tube array is alternately changed for each stage of the tube array. It has excellent effects such as no deviation in the temperature distribution of the flowing heating fluid in the direction of the bayonet heat transfer tube, no deviation in the heating fluid, and improvement in heat exchange performance.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a crossflow bayonet heat exchanger of the present invention.

FIG. 2 is a front sectional view of a conventional cross-flow type bayonet heat exchanger.

FIG. 3 is a graph showing a temperature distribution of a heating fluid in a conventional crossflow bayonet heat exchanger.

FIG. 4 is a graph showing a temperature distribution of a heating fluid of the crossflow bayonet heat exchanger of the present invention.

FIG. 5 is a view taken in the direction of arrows AA in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bayonet heat transfer tube 1a Outer tube 1b Inner tube 1c Tip of bayonet heat transfer tube 1d Base end of bayonet heat transfer tube 3 Fluid to be heated 4 Heated fluid flow path 5 Heated fluid

Claims (1)

[Claims] 1. A tube group of a bayonet heat transfer tube including an outer tube having a blinded end and an inner tube inserted therein is inserted into a heating fluid flow path in a direction in which a heating fluid flows and a direction of the bayonet heat transfer tube. A cross-flow type bayonet heat exchanger inserted so that they are orthogonal to each other, and a pair of bayonet heat transfer tube groups such that the direction of the bayonet heat transfer tube row changes alternately for each stage of the tube row. A cross-flow type bayonet heat exchanger, wherein the first and second bayonet heat transfer tubes are arranged so that the front end of the one bayonet heat transfer tube is close to the base end of the other bayonet heat transfer tube.