JPS6220660A - Air preheater - Google Patents

Abstract

PURPOSE:To improve heat exchange efficiency by constituting an air preheater which is suitable for a Stirling engine and carries out the heat exchange between the combustion exhaust gas and combustion air by accommodating a plurality of superposed annular heat transmitting plates into a case having an annular space. CONSTITUTION:A heater 5 for heating the working fluid in a Stirling engine is equipped with a combustion chamber 15 installed so as to surround the head of an expansion cylinder, and the fuel jetted out from a burner 17 is combusted under the supply of the air preheated by the combustion exhaust gas in an air preheater 18. In this case, the air preheater 18 is constituted by accommodating a plurality of superposed annular heat transmitting plates 33 having a plurality of semicircular cut parts 35 and 36 in the peripheral direction onto the inner and outer peripheral edge parts formed into stepped collar form, into the annular space 23 of a case 24 arranged, keeping a gap, onto the basic plate 22 having a center opened hole 21. Combustion air and combustion exhaust gas are allowed to circulate in the inner and outer annular spaces 38 and 39 partitioned by the stepped part 34 of each heat transmitting plate 33.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an air preheater, and more particularly, to an air preheater suitable for being incorporated into a heater of a Stirling engine, for example.

[Technical background of the invention and its problems]

Recently, as part of efforts to save energy, the Stirling engine has been reviewed and intensive research is being conducted. There are various types of Stirling engines, for example,
Taking a two-piston system as an example, a regenerative heat exchanger is connected in a closed flow path configuration between two power cylinders each containing a built-in power piston, and a regenerative heat exchanger is connected between one end of the regenerative heat exchanger and one power cylinder. The flow path between the regenerative heat exchanger and the other power cylinder is heated by a heater, and the flow path between the other end of the regenerative heat exchanger and the other power cylinder is cooled by a cooler. This engine is characterized by its high theoretical thermal efficiency and the ability to use any heat source.

By the way, what about the Stirling engine heater?

Typically, there is a combustion chamber that burns gas or liquid fuel, a heat exchanger that heats the working fluid necessary to operate the Stirling engine using the high-temperature combustion gas obtained by combustion, and a combustion exhaust gas that preheats the combustion air. It consists of an air preheater and an air preheater.

In the case of a Stirling engine, the higher the heating temperature of the working fluid described above, the higher the efficiency. Therefore, the higher the combustion flame temperature, the better. For this reason, a method has been adopted in which an air preheater is provided, and the air preheater recovers the heat of the exhaust gas to raise the combustion air to a high temperature, thereby increasing the combustion flame temperature.

The air preheater used for the above purpose desirably has a large heat transfer area in order to efficiently recover heat from exhaust gas. However, increasing the heat transfer area generally results in a corresponding increase in the overall size of the air preheater, and also increases heat dissipation losses, reducing efficiency. For this reason, in many conventional air preheaters, a plurality of pipes are arranged around the combustion chamber, and these pipes are connected by welding.

However, the conventional air preheater configured as described above has a complicated structure, takes a long time to manufacture, and has a small heat transfer area despite its large weight.

There was a problem with low heat exchange efficiency.

[Purpose of the invention]

The present invention was made in view of these circumstances, and its purpose is to facilitate manufacturing.

The object of the present invention is to provide an air preheater that can increase the heat transfer area and reduce the overall weight.

[Summary of the invention]

According to the present invention, in the air preheater that performs heat exchange between combustion exhaust gas and combustion air guided to the combustor,
A case arranged to surround a combustion chamber and having an annular space surrounding the combustion chamber therein; and a case that is housed in a stacked state in the annular space of the case in the axial direction of the annular space.

A plurality of annular heat exchanger plates each having a partition wall portion that partitions the annular space into an inner annular space and an outer annular space in the laminated state, and having a plurality of inner notches and outer notches on the inner and outer peripheral edges.

Means for causing one fluid to flow through the inner annular space through the inner notch, and means for causing the other fluid to flow through the outer annular space through the outer notch, including combustion exhaust gas and combustion air. An air preheater is provided.

〔Effect of the invention〕

According to the present invention, the above configuration is adopted.

An annular heat exchanger plate with high mechanical strength is not required.

This makes it possible to use extremely thin annular heat exchanger plates.
A large number of annular heat exchanger plates can be accommodated within a case with limited volume. Therefore, the heat transfer area can be significantly increased, and as a result, the heat exchange efficiency can be improved. Furthermore, since an extremely thin annular heat exchanger plate can be used, not only can the overall weight be reduced, but also the temperature of the preheated air can be raised quickly as the heat capacity decreases, making it possible to obtain high temperature preheated air in a short time. Furthermore, since the annular heat exchanger plate can be made thin, the annular heat exchanger plate can be easily manufactured by press working or the like. Therefore, manufacturing can also be facilitated.

[Embodiments of the invention] Two embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a longitudinal sectional view of a two-piston Stirling engine incorporating an air preheater according to an embodiment of the present invention.

That is, this Stirling engine is broadly divided into a power cylinder 1 (hereinafter referred to as an expansion cylinder) used for expanding one working fluid, and a power piston 2 slidably mounted within the expansion cylinder 1. (Hereafter referred to as °expansion piston.)

A power cylinder 3 (hereinafter referred to as a compression cylinder) provided in a compression space for working fluid; a power piston 4 (hereinafter referred to as a compression piston) slidably mounted within this compression cylinder 3; Expansion cylinder 1 and compression cylinder 3
The heater provided between 5. Connecting rods 8, 9 . It consists of an output shaft 12 connected via a crankshaft 10.11.

The heater 5 includes a combustion chamber 15 formed by disposing a heat insulating material 14 in a part so as to surround the head 13 of the expansion cylinder 1, and a plurality of heat exchangers 16 disposed within the combustion chamber 15. Burner 17 arranged to face combustion chamber 15
and an air preheater 18 that is arranged to surround the combustion chamber 15 and preheats the air necessary for combustion with combustion exhaust gas.

Each of the heat exchangers 16 has a rod-like outer shape, and one end of each fluid passage communicates with the top of the expansion cylinder 1, and the other end communicates with a manifold 19 formed within the head 13. They are arranged so as to form a funnel as a whole. The manifold 19 is connected to a regenerative heat exchanger 6 via a connecting pipe 20, and this regenerative heat exchanger 6 is connected to the top inside the compression cylinder 3 via a cooler 57 constituted by the heat exchanger. A space surrounded by the expansion cylinder 1 and the expansion piston 2, each heat exchanger 16. Manifold 19. Connecting pipe 20. Regenerative heat exchanger6. Cooler 7,
A closed space defined by the compression cylinder 3 and the compression piston 4 is filled with He as a working fluid.

Specifically, the air preheater 18 is constructed as shown in FIGS. 2 and 3.

That is, a base plate 22 is provided in the center thereof, which has a hole 21 into which the top of the expansion cylinder 1 fits.

A case 24 having an annular space 23 surrounding the combustion chamber 15 therein is disposed on the upper side of the substrate 22 in the figure with a predetermined gap 25 provided between the case 24 and the substrate 22 . In addition,
The outer peripheral edge of the above-mentioned 1111125 is closed by an extension of the outer wall component of the case 24. An outer cover 27 that forms a passage 26 between the outer peripheral surface and the upper surface of the case 24 is provided at a position facing the outer peripheral surface and the upper surface of the case 24.
An air inlet 28 for introducing air into the passage 26 is formed at the lower part of the outer cover 27 in the figure. An inner cover 30 is provided inside the case 24 and forms a passage 29 between it and the inner peripheral surface of the case 24 . The first passage 29 communicates with the space where the burner 17 is located via the swirler 31.

A heat transfer body 32 is housed within the case 24. The heat transfer body 32 is constructed by laminating a plurality of annular heat transfer plates 33 formed of thin, good heat conductive plates in the axial direction of the annular space 23 . As shown in FIG. 3, each annular heat exchanger plate 33 is formed into a stepped flange shape having a stepped portion 34 at an intermediate position in the radial direction. In addition, each annular heat exchanger plate 33 includes
A plurality of semicircular inner notches 35 are formed in the circumferential direction on the inner peripheral edge thereof, and a plurality of semicircular outer notches 36 are also formed in the circumferential direction on the outer peripheral edge thereof.

Each annular heat exchanger plate 33 formed as described above is
The heat transfer body 32 described above is constructed by stacking adjacent step portions 34 with their bending directions reversed to each other, and in this state being integrated in the stacking direction with through bolts 37.

Therefore, inside the case 24 in which the heat transfer body 32 is housed,
The step portion 34 formed in each annular heat transfer plate 33 acts as a partition wall to partition the space into an inner annular space 38 and an outer annular space 39 .

Therefore, the inner annular space 38 and the passage 2 are located at a plurality of locations on the upper wall of the case 24 in the figure, located closer to the center.
A hole 40 is provided to communicate with the case 2.
Holes 41 for communicating the inner annular space 38 and the passage 29 are provided at a plurality of locations in the lower part of the inner wall 4 in the figure. In addition, holes 42 are provided at a plurality of locations on the bottom wall of the case 24 on the outside side to allow communication between the gap 25 and the outer annular space 39, and holes 42 are provided on the top wall of the case 24 on the outside side. Exhaust pipe 4 is connected to a lever whose one end side communicates with outer annular space 39.
3 is connected. The other end of the exhaust pipe 43 passes through the outer cover 27 and is led to the outside.

In FIG. 1, 51 indicates a crank chamber containing lubricating oil to a predetermined level, 52 and 53 indicate linear bearings, 54 indicates piping for guiding the refrigerant of the cooler 7, and 5
5.56 indicates insulation material.

57 and 58 in FIG. 2 indicate seal rings.

With such a configuration, when the output shaft 12 is temporarily rotated by an external power source while the burner 17 is ignited and the refrigerant is flowing through the pipe 54, the output shaft 12 is connected to the crankshaft 10. 11, the expansion piston 2 and compression piston 4, which are connected via connecting rods 8 and 9, reciprocate with a certain phase difference. When the expansion piston 2 moves to the compression stroke due to this reciprocating movement, He in the expansion cylinder 1 is transferred to each heat exchanger 16. Manifold 19. Connecting pipe 20
．． Regenerative heat exchanger6. It flows into the compression cylinder 3 via the cooler 7, and when the expansion piston 2 reaches the top dead center, H
Most of e flows into the compression cylinder 3. At this time, while the He passes through the regenerative heat exchanger 6, the heat it retains is taken away by the regenerative heat exchanger 6, and when it passes through the cooler 7, it is further cooled. When the compression piston 4 begins to move from the bottom dead center toward the top dead center as the output shaft 12 rotates, the low-temperature He in the compression cylinder 3 is compressed, and is moved to the expansion cylinder 1 in the opposite path. Flow inward. At this time, He absorbs heat while passing through the regenerative heat exchanger 6 and is heated to a high temperature, and is further heated when passing through each heat exchanger 16.

The high temperature He that has flowed into the expansion cylinder 1 expands and pushes down the expansion piston 2. Thereafter, the above-described operations are repeated, and even when the external power source is cut off, the output shaft 12 continues to rotate, and functions as a Stirling engine.

By the way, in the above operating state, the air preheater 18 operates as follows. Namely.

The air necessary to burn the fuel injected from the burner 17 is supplied to the air introduction hole 28 as shown by the solid line arrow in FIG.
- passage 26 - hole 40 - inner annular space 38 - hole 41 - passage 29 - swirler 31 - combustion air 15.

Further, after heating each heat exchanger 16, the combustion gas generated in the combustion chamber 15 is transferred from the gap 25 to the hole 42 to the outer annular space 39 to the exhaust pipe 43, as shown by the thick arrow in FIG. Flows in the path. Therefore, the combustion air flows through the outer wall of the case 24, each annular heat exchanger plate 33. It will be heated to a high temperature by the combustion exhaust gas through the inner cover 30.

In this case, in particular, a case 24 having an annular space 23 surrounding the combustion chamber 15 is provided.

A heat transfer body 32 configured by laminating annular heat transfer plates 33 having the above-mentioned structure is housed in this case 24, and the heat transfer body 32 is mainly used to exchange heat between combustion exhaust gas and combustion air. . With such a heat exchange section configuration, almost no mechanical force is applied to the annular heat exchanger plate 33, so the thickness of the annular heat exchanger plate 33 can be made very thin. For this reason,
A large number of annular heat exchanger plates 33 are installed in a case 24 with a limited volume.
As a result, the heat transfer area can be set significantly wider, and the heat exchange efficiency can be improved. Furthermore, an extremely thin annular heat exchanger plate 33 can be used.

Not only can the overall weight be reduced, but the rise in preheated air temperature can be made faster as the heat capacity decreases, and high temperature preheated air can be obtained in a short time. Furthermore, the annular heat exchanger plate 33
The annular heat exchanger plate 3 can be made thinner by pressing, etc.
3 can be easily manufactured and the overall manufacturing can be facilitated, so that the above-mentioned effects can be achieved after all.

Note that the present invention is not limited to the embodiments described above. That is, in the embodiment described above, each annular heat exchanger plate 33
Each annular heat exchanger plate 3 is arranged so that the inner notch 35 and the outer notch 36 formed in the annular heat exchanger plate 3 are aligned in the axial direction.
3 are laminated, but they may be laminated so that the inner notches and outer notches of adjacent annular heat exchanger plates 33 are shifted in the circumferential direction. Further, the annular heat exchanger plate that comes into contact with the high temperature combustion exhaust gas may be formed of a material with high heat resistance.

Furthermore, the annular heat exchanger plate does not necessarily have to be annular, but may be annular. Further, in the above-described embodiment, the two-step portion 34 functions as a partition wall, but an annular protrusion may be provided so that the protrusion functions as a partition wall. Further, the air preheater according to the second invention is not limited to use only in Stirling engines, but can of course be used in various types of combustors. others.

Various modifications can be made without departing from the spirit of the invention.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a Stirling engine incorporating an air preheater according to an embodiment of the present invention. FIG. 2 is a vertical cross-sectional view showing only the air preheater of the engine, and FIG. 3 is a partially cutaway perspective view showing a heat transfer body incorporated in the air preheater. 1... Expansion cylinder, 2... Expansion piston, 3...
・Compression cylinder, 4... Compression piston, 5... Heater, 6... Regeneration heat exchanger, 7... Cooler, 15...
・Combustion chamber, 16... Heat exchanger, 17... Burner, 1
8...Air preheater. 23... Annular space, 24... Case, 32... Heat transfer body. 33... Annular heat exchanger plate, 35... Inner notch, 36
...Outer notch, 38...Inner annular space, 39.
...outer annular space.

Claims (4)

[Claims] (1) In an air preheater that performs heat exchange between combustion exhaust gas and combustion air guided to a combustor, a case is arranged to surround a combustion chamber and has an annular space inside the combustion chamber. , partition wall portions each housed in the annular space of the case in a stacked state in the axial direction of the annular space, and partitioning the annular space into an inner annular space and an outer annular space in the stacked state. and a plurality of annular heat exchanger plates having a plurality of inner and outer notches on the inner and outer peripheral edges, and a fluid of either combustion exhaust gas or combustion air is introduced into the inner annular space through the inner notches. An air preheater comprising: means for causing fluid flow; and means for causing the other fluid to flow through the outer annular space through the outer notch. (2) The air preheater according to claim 1, wherein the partition wall portion is constituted by a step portion formed in the middle of the annular heat exchanger plate in the radial direction. (3) Each of the annular heat exchanger plates is laminated in such a manner that inner notches and outer notches formed in adjacent annular heat exchanger plates are displaced from each other in the circumferential direction. An air preheater according to scope 1. (4) The air preheater according to claim 1, wherein the annular heat exchanger plate is made of different materials for those that come into contact with high-temperature combustion exhaust gas and for the other parts.