JP2014152949A - Heat transfer pipe and waste heat recovery boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transfer heat from one fluid to the other fluid with high efficiency.SOLUTION: A heat transfer pipe includes a pipe 2 forming a passage in which a first fluid flows; and a fin 3 formed into a plate shape. The fin 3 is formed by a solid portion 11 joined to the outer side of the pipe and multiple fin portions 12-1 to 12-n which are indirectly joined to the pipe through the solid portion 11. In the solid portion 11, multiple structures which agitate a second fluid flowing near the solid portion 11 are formed. In the heat transfer pipe, the multiple protrusions agitate the second fluid thereby making a thermal boundary layer of the second fluid, which is formed near the fin 3, thin. An amount of heat exchanged between the first fluid and the second fluid is increased in the heat transfer pipe compared to other heat transfer pipes where the solid portion 11 is generally formed into a flat shape.

Description

  The present invention relates to a heat transfer tube and an exhaust heat recovery boiler, and more particularly to a heat transfer tube and an exhaust heat recovery boiler used when recovering exhaust heat.

  An exhaust heat recovery boiler that recovers exhaust heat from high temperature exhaust gas is known. The exhaust heat recovery boiler is provided with a heat transfer tube in a flue through which exhaust gas flows. The heat transfer tube is formed by joining fins to the outside of the tube. The heat transfer tube transfers the heat of the exhaust gas to the water by flowing water through the heat transfer tube when high-temperature exhaust gas is flowing around the heat transfer tube. At this time, the fin diffuses the exhaust gas and further increases the amount of heat transferred from the heat of the exhaust gas to the fluid (for example, see Patent Document 1).

US Pat. No. 5,337,807

  Such a heat transfer tube is desired to have improved performance, and it is desired to transfer heat from one fluid to the other with higher efficiency.

  An object of the present invention is to provide a heat transfer tube and an exhaust heat recovery boiler that transfer heat from one fluid to the other with high efficiency.

  The heat transfer tube according to the present invention includes a tube that forms a flow path through which the first fluid flows, and fins that are formed in a plate shape. The fin is formed of a solid portion joined to the outside of the tube and a plurality of fin portions joined indirectly to the tube via the solid portion. The solid portion is formed with a plurality of structures that stir the second fluid flowing in the vicinity of the solid portion.

  In such a heat transfer tube, when the second fluid is agitated by the plurality of protrusions, the temperature boundary layer of the second fluid formed in the vicinity of the fin can be thinned, and the solid portion is Compared with other heat transfer tubes formed substantially flat, the amount of heat exchange between the first fluid and the second fluid can be increased.

  Each of the plurality of structures protrudes from the surface formed in the solid portion.

  In such a heat transfer tube, the second fluid is agitated by the plurality of protrusions, so that the temperature boundary layer of the second fluid formed in the vicinity of the fin can be thinned. Such a heat transfer tube has a larger area used for heat transfer in the solid portion than other heat transfer tubes in which a plurality of dimples or a plurality of holes are formed in the solid portion, Heat can be more efficiently transferred from the fin portion to the tube.

  Arbitrary structures of the plurality of structures are arranged such that the distance from any structure to any of the plurality of fins is less than the distance from any structure to the tube .

  Such a heat transfer tube can more appropriately agitate the second fluid than the other heat transfer tube in which a plurality of structures are formed in the vicinity of the tube of the solid portion. The amount of heat exchange between the first fluid and the second fluid can be increased.

  The plurality of structures include a plurality of first structures and a plurality of second structures. The arbitrary first structure of the plurality of first structures has a first distance from the arbitrary first structure to any one of the plurality of fins. The distance from the arbitrary first structure to the tube It arrange | positions so that it may become longer. Arbitrary second structures of the plurality of second structures are arranged such that a second distance from the arbitrary second structure to any of the plurality of fins is longer than the first distance. Yes.

  In such a heat transfer tube, the second fluid is more appropriately agitated by the plurality of protrusions than the other heat transfer tube in which only the plurality of first structures are formed, so that The temperature boundary layer of the second fluid formed in the vicinity can be thinned, and the amount of heat exchange between the first fluid and the second fluid can be increased.

  The exhaust heat recovery boiler according to the present invention includes the heat transfer tube according to the present invention and a duct that forms a flow path through which the first fluid flows. At this time, the second fluid is exhaust gas exhausted from the combustion facility. The heat transfer tube heats the first fluid.

  Such an exhaust heat recovery boiler can heat the first fluid with high efficiency because the heat transfer tube can transfer heat with high efficiency.

  The heat transfer tube and the exhaust heat recovery boiler according to the present invention can transfer heat from one fluid to the other with high efficiency.

It is a longitudinal cross-sectional view which shows the heat exchanger tube by this invention. It is a cross-sectional view which shows the heat exchanger tube by this invention. It is a perspective view which shows the heat exchanger tube by this invention. It is a longitudinal cross-sectional view which shows several protrusion. It is a cross-sectional view which shows the flow of the waste gas which flows through the vicinity of a heat exchanger tube. It is a cross-sectional view which shows the other form of implementation of the heat exchanger tube by this invention.

  Hereinafter, an embodiment of a heat transfer tube will be described with reference to the drawings. The heat transfer tube 1 includes a tube 2 and fins 3 as shown in FIG. The tube 2 is made of metal and is formed in a tubular shape. The pipe 2 forms a flow path 5 therein. The fin 3 is formed of a metal plate and is formed in a strip shape. The fin 3 is joined to the tube 2 along a spiral on the outer wall of the tube 2 so as to protrude outward from the outer wall of the tube 2.

  As illustrated in FIG. 2, the fin 3 includes a solid portion 11 and a plurality of fin portions 12-1 to 12-n (n = 2, 3, 4,...). The solid portion 11 forms the side of the fin 3 that is joined to the tube 2. Arbitrary fin portions 12-i (i = 1, 2, 3,..., N) of the plurality of fin portions 12-1 to 12-n are formed in a substantially rectangular shape and are not joined to the tube 2 and are solid. It is joined to the portion 11.

  As shown in FIG. 3, the fin 3 is further formed with a plurality of protrusions 14-1 to 14-n. The plurality of protrusions 14-1 to 14-n correspond to the plurality of fin portions 12-1 to 12-n and are formed on the solid portion 11. The protrusion 14-i corresponding to the fin portion 12-i of the plurality of protrusions 14-1 to 14-n is formed in the vicinity of the fin portion 12-i of the solid portion 11. The protrusion 14-i is further formed at a predetermined distance from the fin portion 12-i, and the distance from the protrusion 14-i to the fin portion 12-i is greater than the distance from the protrusion 14-i to the tube 2. It is formed to be shorter. The protrusions 14-i are formed in a hemispherical shape as shown in FIG.

  The manufacturing method for manufacturing the heat transfer tube 1 includes an operation of manufacturing a fin component and an operation of joining the fin component to the tube. In the operation of manufacturing the fin, first, a strip-shaped plate is prepared. The plate is processed so that a plurality of cuts are formed. Each of the plurality of cuts is formed so as to be cut perpendicularly from the edge on one side to the edge, and is formed along a plurality of parallel lines arranged at a predetermined interval. The plurality of cuts are further formed so as not to reach a region of the plate that is separated from the edge by a predetermined length. The plate is further processed to form a plurality of protrusions, thereby forming the fin component. The plate is formed in a region separated from the edge by a predetermined length. The predetermined length is longer than the cut length. The plurality of protrusions further correspond to the plurality of cuts. A protrusion corresponding to a certain notch among the plurality of protrusions is formed between a straight line along which the notch is along and a straight line along which another notch adjacent to the notch is located.

  In the operation of joining the fin part to the pipe, the pipe is first prepared. The tube is formed so that the outer wall surface is along the side surface of the cylinder. The fin component is welded to the outer wall of the tube at the opposite edge of the fin component from the side where the plurality of cuts are formed. The fin part is joined to the outer wall of the pipe so that the locus of the point of the outer wall of the pipe joined to the fin part is formed in a spiral. The heat transfer tube 1 is manufactured by joining the tube and the fin component in this manner.

  The heat transfer tube 1 is applied to an exhaust heat recovery boiler. The exhaust heat recovery boiler includes a heat transfer tube 1 and a duct. The heat transfer tube 1 is arranged in a flue formed by the duct so that a straight line along the duct and a straight line along the heat transfer tube 1 are perpendicular to each other. The exhaust heat recovery boiler causes high-temperature exhaust gas exhausted from a combustion device exemplified by the boiler to flow through the flue, and causes water to flow through the flow path 5 of the heat transfer tube 1. The exhaust gas flows in the vicinity of the heat transfer tube 1 when flowing through the flue.

  When the exhaust gas flows in the vicinity of the heat transfer tube 1, the heat transfer tube 1 is heated by being brought into contact with the heat transfer tube 1, and is cooled by the heat transfer tube 1. At this time, the heat transferred from the exhaust gas to the fins 3 of the heat transfer tube 1 is transferred to the tube 2 and transferred to the water flowing in the flow path 5. That is, when the heat transfer tube 1 is in contact with the exhaust gas, the heat transfer tube 1 heats the water by transferring the heat of the exhaust gas to the water flowing in the flow path 5.

  The flow of exhaust gas flowing in the vicinity of the fins 3 of the heat transfer tube 1 includes a fin partial flow 21 and a solid partial flow 22 as shown in FIG. The fin partial flow 21 indicates the flow of exhaust gas flowing in the vicinity of the plurality of fin portions 12-1 to 12-n. The solid partial flow 22 indicates the flow of exhaust gas that flows closer to the solid portion 11 than the fin partial flow 21. The fin portion flow 21 is a temperature boundary layer of the exhaust gas that is formed in the vicinity of the fin portions 12-1 to 12-n by stirring the exhaust gas by the edges of the fin portions 12-1 to 12-n. Reduce the thickness. In the solid partial flow 22, the exhaust gas is stirred by the plurality of protrusions 14-1 to 14-n, and the thickness of the temperature boundary layer of the exhaust gas formed in the vicinity of the solid portion 11 is reduced. The fin 3 is more efficiently transferred from the exhaust gas as the temperature boundary layer of the exhaust gas is thinner.

  When the plurality of projections 14-1 to 14-n are not formed on the solid portion 11, the exhaust gas formed in the vicinity of another solid portion where the plurality of projections 14-1 to 14-n are not formed. The temperature boundary layer becomes relatively thick and the efficiency of heat transfer from the exhaust gas to the solid part is relatively poor. Such a heat transfer tube 1 can make its temperature boundary layer thinner than other heat transfer tubes in which a plurality of protrusions are not formed, and transfer the heat of the exhaust gas to the water more efficiently. Can be heated.

  The plurality of protrusions 14-1 to 14-n may not correspond to the plurality of fin portions 12-1 to 12-n. That is, the heat transfer tube has its temperature boundary layer formed in the same manner as the heat transfer tube 1 in the above-described embodiment when a sufficient number of projections are formed on the solid portion 11 to diffuse the exhaust gas. The heat of the exhaust gas can be transferred to the water with high efficiency.

  The plurality of protrusions 14-1 to 14-n may be formed on both sides of the back and front of the fin 3. Such a heat transfer tube can reduce the temperature boundary layer in the same manner as the heat transfer tube 1 in the above-described embodiment, and can transfer the heat of the exhaust gas to the water with high efficiency. . Such a heat transfer tube can make the temperature boundary layer thinner than the heat transfer tube 1 in the above-described embodiment, and can transfer the heat of the exhaust gas to the water more efficiently. Can do.

  In another embodiment of the heat transfer tube, the fin 3 in the above-described embodiment is replaced with another fin. The fin 30 includes a solid portion 31 and a plurality of fin portions 32-1 to 32-n as shown in FIG. The solid portion 31 forms the side of the fin 30 that is joined to the tube 2. An arbitrary fin portion 32-i among the plurality of fin portions 32-1 to 32-n is formed in a substantially rectangular shape and is joined to the solid portion 31 without being joined to the tube 2.

  The solid portion 31 is formed with a plurality of first protrusions 34-1 to 34-n and a plurality of second protrusions 35-1 to 35-n. The plurality of first protrusions 34-1 to 34-n correspond to the plurality of fin portions 32-1 to 32-n. The first protrusion 34-i corresponding to the fin portion 32-i of the plurality of first protrusions 3-1 to 34-n is formed in the vicinity of the fin portion 32-i of the solid portion 31. The first protrusion 34-i is further formed at a position away from the fin portion 32-i by a predetermined distance, and the distance from the first protrusion 34-i to the fin portion 32-i is from the first protrusion 34-i. It is formed so as to be shorter than the distance to the tube 2.

  The plurality of second protrusions 35-1 to 35-n correspond to the plurality of fin portions 32-1 to 32-n. The second protrusion 35-i corresponding to the fin portion 32-i among the plurality of second protrusions 35-1 to 35-n is formed in the vicinity of the first protrusion 34-i. The second protrusion 35-i is further formed at a position away from the fin portion 32-i by a predetermined distance, and the distance from the second protrusion 35-i to the fin portion 32-i is from the first protrusion 34-i. It is formed to be longer than the distance to the fin portion 32-i.

  The heat transfer tube to which the fin 30 is applied is also the temperature boundary of the exhaust gas formed in the vicinity of the fin 30 in the same manner as the heat transfer tube 1 in the above-described embodiment when the exhaust gas is flowed in the vicinity of the fin 30. The layer can be made thin, and the heat of the exhaust gas can be transferred to the water flowing through the flow path 5 with high efficiency. Such a heat transfer tube has a plurality of second protrusions 35-1 to 35-n formed at a position close to the tube 2 in the solid portion 31, so that the heat transfer tube in the above-described embodiment is further provided. Compared to 1, the temperature boundary layer of the exhaust gas formed in the region close to the pipe 2 in the solid portion 31 can be made thinner, and the heat of the exhaust gas can be transferred to the water more efficiently. Can do.

  The plurality of protrusions 14-1 to 14-n (the plurality of first protrusions 34-1 to 34-n and the plurality of second protrusions 35-1 to 35-n) are formed in other shapes different from the hemisphere. You can also. Examples of the shape include a column (cylinder, prism) and a cone (cone, pyramid). Similarly to the heat transfer tube 1 in the above-described embodiment, the heat transfer tube to which the projection having such a shape is applied can reduce the temperature boundary layer of the exhaust gas formed in the vicinity of the fin. Heat can be transferred to the water with high efficiency.

  The plurality of protrusions 14-1 to 14-n (the plurality of first protrusions 34-1 to 34-n and the plurality of second protrusions 35-1 to 35-n) are further different from the protrusions. It can also be formed. As the structure, a dent (dimple) and a hole penetrating from the front side to the back side of the solid portion 11 are exemplified. The heat transfer tube in which such a structure is formed is also formed in the vicinity of the fin by agitating the exhaust gas by the plurality of structures in the same manner as the heat transfer tube 1 in the above-described embodiment. The temperature boundary layer of the exhaust gas can be thinned, and the heat of the exhaust gas can be transferred to the water with high efficiency. Here, the heat transfer tube 1 in the above-described embodiment has a plurality of fin portions 12 because the volume of the solid portion 11 is larger than that of the heat transfer tube to which a structure that does not protrude from the solid portion 11 is applied. Heat can be transferred from the -1 to 12-n to the pipe 2 with higher efficiency, and the heat of the exhaust gas can be transferred to the water with higher efficiency.

1: Heat transfer tube 2: Tube 3: Fin 5: Flow path 11: Solid portion 12-1 to 12-n: Plural fin portions 14-1 to 14-n: Plural protrusions 21: Fin portion flow 22: Solid portion Flow 30: Fin 31: Solid portion 32-1 to 32-n: Plural fin portions 34-1 to 34-n: Plural first protrusions 35-1 to 35-n: Plural second protrusions

Claims (5)

A tube forming a flow path through which the first fluid flows;
A fin formed in a plate shape,
The fin is
A solid portion joined to the outside of the tube;
A plurality of fin portions indirectly joined to the tube via the solid portion;
The solid portion is a heat transfer tube in which a plurality of structures that stir the second fluid flowing in the vicinity of the solid portion are formed.   The heat transfer tube according to claim 1, wherein each of the plurality of structures protrudes from a surface formed in the solid portion.   Arbitrary structures of the plurality of structures are arranged such that a distance from the arbitrary structure to any one of the plurality of fins is shorter than a distance from the arbitrary structures to the pipe. The heat transfer tube according to any one of claims 1 and 2. The plurality of structures are:
A plurality of first structures;
A plurality of second structures,
The arbitrary first structure of the plurality of first structures has a first distance from the arbitrary first structure to any one of the plurality of fins, which is a distance from the arbitrary first structure to the pipe. Arranged to be longer,
An arbitrary second structure of the plurality of second structures is arranged such that a second distance from the arbitrary second structure to any of the plurality of fins is longer than the first distance. The heat transfer tube according to any one of claims 1 to 2. A heat transfer tube according to any one of claims 1 to 4;
A duct that forms a flow path through which the first fluid flows,
The first fluid is exhaust gas exhausted from a combustion facility,
The heat transfer tube is an exhaust heat recovery boiler that heats the second fluid.

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