JPS62189356A - Air preheater - Google Patents

Abstract

PURPOSE:To make the air preheater of a stirling engine an efficient device having a better sealing quality by forming it through a stack of annular plates provided with a number of bores formed in the circumferential direction and mutually separated from others at annular projecting parts formed in the middle of annular parts. CONSTITUTION:On the occasion of forming an air preheater surrounding the combustion chamber 15 of a stirling engine, a number of annular plates 31 having center holes of combustion-chamber space are formed through stacking. The annular plate 31 is equipped with a number of holes 34a in outer perimeter and a number of holes 33a in inner perimeter, and it has an annular projection 32 between them and through stacking at the annular projection part 32, each annular plate 31 is provided with an interval and at the same time a combustion air passage is formed by a hole 34a, and also a combustion gas passage by a hole 33a. A space between respective passages 34a and 33a is sealed by the annular projection 32.

Description

[Detailed description of the invention] :T? The present invention relates to an air preheater, and more particularly to an air preheater suitable for preheating combustion air in a Stirling engine heater or the like.

(Prior Art) Recently, Stirling engines have been attracting attention as a part of energy conservation. There are various types of Stirling engines, but for example, in a two-piston type, a regenerator is connected between the expansion cylinder and the compression cylinder, and the engine operates in the flow path between the regenerator and the expansion cylinder. The structure is such that the fluid is heated and the fluid is cooled in the flow path between the regenerator and the compression cylinder. This m-sensor has the characteristics of high theoretical thermal efficiency and the ability to use any heat source.

By the way, the working fluid heater in a Stirling engine usually includes a combustion chamber that forms a combustion flame using gas or liquid fuel, and a heat exchanger located within the combustion chamber that transfers heat to all the fluids by radiation and convection. , and an air preheater that preheats the combustion air introduced into the combustion chamber by heat exchange with combustion exhaust gas.

In the case of a Stirling engine, the higher the heating temperature of the working fluid by the heater and the lower the cooling water temperature in the cooler, the higher the efficiency, but there is a limit to lowering the cooling water temperature, so the temperature of the combustion flame is raised as much as possible. There is a need to. To achieve this, it is necessary to efficiently recover the heat from the combustion exhaust gas using an air preheater to make the combustion air as high as possible. Therefore, it is desirable to increase the heat transfer area of the air preheater, but an increase in the heat transfer area generally leads to an increase in the size of the air preheater and an increase in heat radiation loss, leading to a decrease in the efficiency of the heater.

Therefore, the present inventors constructed a heat transfer body by stacking stepped annular plates in an annular space formed to surround a combustion chamber, or by stacking annular plates via an annular convex portion. , fluid passages passing through each annular plate are formed on the inner and outer periphery sides separated by the stepped portion or annular convex portion of this heat transfer body, and combustion air is supplied to either one of these fluid passages. An air preheater with a structure in which one side is made to pass through the combustion exhaust gas, and the other is made to pass the combustion exhaust gas, is proposed by I-Plan (Japanese Patent Application No. 159339/1982).

This air preheater has a structure in which the heat transfer body is made of stacked annular plates, so it has a large heat transfer area even though it is small, and by making the annular plates into a thin plate, it is possible to reduce heat loss. 1) Excellent advantages.

(Problems to be Solved by the Invention) In the air preheater with the laminated structure described above, a thin plate of, for example, about 0.3j* is used as the annular plate that is a component of the heat transfer body in order to sufficiently reduce the heat capacity. There is a need. However, when such thin annular plates are stacked together via a step or annular protrusion, elasticity occurs in the stacked state, making it difficult to bring the annular plates into strong contact with each other at the step or annular protrusion.

Therefore, it is not possible to provide a sufficient seal between the two fluid passages through which combustion air and combustion exhaust gas flow, resulting in a problem that the combustion air and combustion exhaust gas partially mix, resulting in a decrease in heat exchange efficiency. be.

The present invention has been made to solve these problems, and it achieves an increase in heat transfer area while reducing size and heat loss, and also improves the fluid flow through which combustion air and combustion exhaust gas flow. It is an object of the present invention to provide an air preheater that is highly efficient by ensuring sealing between passages.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention includes an annular space formed around the combustion chamber, which protrudes toward one side in the radial middle part. A bent portion is formed continuously along the circumferential direction, and wAm is formed on the inner and outer circumferential sides of the bent portion.
A heat transfer body is provided in which a plurality of annular plates each having a plurality of holes each forming a fluid passage are laminated so that the bent portions are interlocked with each other. The combustion air introduced into the combustion chamber is allowed to flow through one of the peripheral and outer fluid passages, and the combustion exhaust gas for preheating the combustion air through heat exchange is allowed to flow through the other. Features.

(Function) In the air preheater according to the present invention, combustion air is passed through one of the fluid passages on the inner circumference side and the outer circumference side of the heat transfer body, and is preheated by the heat of the combustion exhaust gas flowing through the other side. After that, it is guided into the combustion chamber.

Here, in the heat transfer body, the bent portions of the laminated annular plates mesh with each other in a laminated state, thereby isolating, that is, sealing, the two fluid passages.

This sealing effect is due to the meshing of the bent parts, that is, by press-fitting into the convex side of the bent part of the annular plate or the concave side of the bent part of the adjacent annular plate. It is more reliable than one that relies only on

(Example) Hereinafter, practical examples of the present invention will be described with reference to the drawings. 1st
FIG. 1 is a sectional view showing a schematic configuration of a Stirling engine incorporating an air preheater according to an embodiment of the present invention.

As shown in Fig. 1, this Stirling engine includes a power cylinder (expansion cylinder) 1 for expanding working fluid, a power piston (expansion piston) 2 slidably mounted in the M3 expansion cylinder 1, and A heater 5. Regenerator 6 and cooler 7
, and an expansion piston 2 and a compression piston 4
This is a two-piston Stirling engine having a structure in which an output shaft 12 is connected to the output shaft 12 through a connecting rod 8.9 and a crankshaft 10.11, respectively.

The heater 5 includes a combustion chamber 15 arranged via an inner heat insulating material 14 so as to surround the head 13 of the expansion cylinder 1, a plurality of heat exchangers 16 arranged in the combustion chamber 15, and a plurality of heat exchangers 16 arranged in the combustion chamber 15. Gas nozzle 17 and combustion 1
15, and an air preheater 18 that preheats combustion air by heat exchange with combustion exhaust gas.

The heat exchangers 16 are arranged in the shape of a funnel as a whole, and one end of the fluid passage formed inside each of the heat exchangers 16 is connected to the inflated cylinder 1.
The other end is connected to the regenerator 6 via a manifold formed in the head 13 and a connecting pipe 20, respectively. Then, the expansion cylinder 1 and the expansion piston 2
Surrounded by I: space, heat exchanger 16. Manifold 19.
Connecting pipe 20° regenerator 6. Cooler7. A working fluid, for example He, is sealed in a space surrounded by the compression cylinder 3 and the compression piston 4.

In addition, in Fig. 1, 21 is a crank in which 'tIJ pure oil has been accommodated to a predetermined level! , 22.23 is a linear bearing, 24.25 is a pipe that guides the refrigerant of the cooler 7, 2
6 indicates a heat insulating material.

Next, the air preheater 18 according to the present invention will be explained.

FIG. 2 is an enlarged sectional view of the air preheater 11!
A cylindrical case 29 forming an annular space 28 surrounded by 7
In this annular space 28, a heat transfer body 30 having the structure shown in FIG. 3 is arranged.

The heat transfer body 30 is an annular plate 31 made of a thin plate of about 0.3 m+.
It is constructed by stacking a large number of layers at intervals of about 21 meters. Each annular plate 31 constituting the heat transfer body 30 has a bent part 32 protruding toward one surface (in the figure, the upper surface) continuously formed along the circumferential direction at its radially intermediate portion. Furthermore, fluid passages 33 and 34 are provided on the inner and outer circumferential sides of the bent portion 32.
A plurality of holes 33a and 34a are formed,
The bent portions 32 are stacked so as to mesh with each other. That is, the bent portions 32 are formed in a substantially V-shaped cross section with tapered surfaces, and when the bent portions 32 are in mesh with each other, the convex sides thereof are press-fitted into the concave sides of the bent portions of the adjacent annular plates. Ru. The meshing portions of these bent portions 32 isolate or seal the fluid passages 33 and 34.

A heat transfer body 3o made of a laminate of these annular plates 31
An upper 7 flange 37 having a fluid passage hole 35.36 at a position facing both the inner and outer fluid passages 33,34 of the heat transfer body 31 is provided above, and the upper 7 flange 37 has a fluid passage hole 35. Lower flanges 39 each having a fluid passage hole 38 at a position facing the fluid passage 33 and a protrusion that is press-fitted into the concave side of the bent portion 32 of the lowermost annular plate 31 are provided, and these flanges 37 .39 and the case 29 maintain airtightness within the heat transfer body 30.

The heater 5 further includes an outer peripheral fluid passage 34 in the heat transfer body 30.
an air population 40 for introducing combustion air into the inner circumferential fluid passage 3 in the outer circumferential fluid passage 34 in the heat transfer body 30;
a swirler 41 that swirls and supplies combustion air, which has been preheated by heat exchange with the combustion exhaust gas passing through the combustion chamber 3 and then sent through the air passage between the inner insulation material 14 and the outer insulation material 27, into the combustion chamber 15; , an exhaust l1l142 is provided for discharging the combustion exhaust gas to the outside air after preheating the combustion air.

Next, the operation of the Stirling engine configured as described above will be explained. A combustion flame is formed by injecting gas fuel into the combustion chamber 15 from the gas nozzle 17 and supplying combustion air from the swirler 41, and furthermore, with the refrigerant flowing through the pipes 24 and 25,
When the output shaft 12 is temporarily rotated by an external power source, the crankshaft 10.11 and the connecting rod 8
9, the expansion piston 2 and the compression piston 4 reciprocate with a certain phase difference. When the expansion piston 2 moves to the compression stroke due to this reciprocating movement, the working fluid (He) in the expansion cylinder 1 is transferred to the heat exchanger 16° manifold 19. Connecting pipe 20. The working fluid flows into the compression cylinder 3 via the regenerator 6 and the cooler 7, and most of the working fluid flows into the compression cylinder 3 when the expansion piston 2 reaches the top dead center. At this time.

While passing through the regenerator 6, the working fluid loses its retained heat to the regenerator 6, and is then cooled by the cooler 7. When the compression piston 4 starts moving from the bottom dead center toward the top dead center as the output shaft rotates 120 times, the low-temperature working fluid in the compression cylinder 3 is compressed, and the fluid is moved to the expansion cylinder in the opposite path. 1. At this time, the working fluid absorbs heat while passing through the regenerator 6 and is heated to a high temperature, and then is further heated when passing through the heat exchanger 16. The high temperature working fluid that has flowed into the expansion cylinder 1 expands and pushes down the expansion piston 2. Thereafter, the above-mentioned operation is repeated, and even when the external power source is cut off, the output shaft 12 continues to rotate, and the engine operates as a swing engine.

In this operating state of the Stirling engine, the air preheater 18 according to the present invention performs the following actions. The combustion air necessary to burn the gas fuel injected from the gas nozzle 17 is provided at the lower end wall of the cylindrical case 29 between the air inlet 40 and the air preheater 2; 18, as shown by solid arrows in FIG. Slanted fluid passage hole - outer circumferential fluid passage 34 of heat transfer body 30 - outer circumferential fluid passage hole 3 of upper flange 37
It is supplied into the combustion chamber 15 through a route from 6 to swirler 41 to combustion v15.

On the other hand, the combustion gas generated within the combustion chamber 15 is.

After the working fluid is heated through the heat exchanger 16 as shown by the broken line arrow, it becomes combustion exhaust gas and flows from the fluid passage hole 38 of the lower flange 39 of the heat transfer body 30 to the inner fluid passage 33 to the upper flange 37. It is discharged into the atmosphere through a path from the inner circumferential fluid passage hole 35 to the exhaust pipe 42.

Therefore, the combustion exhaust gas is transferred to the inner fluid passage 33 of the heat transfer body 30.
Heat is applied to the combustion air passing through the outer peripheral fluid passage 34. In this case, the inner circumferential side fluid passage 33 and the outer circumferential side fluid passage 34 constitute the heat transfer body 30, and the annular plate 31
Since the combustion air and the combustion exhaust gas are sealed by the meshing portion of the bent portion 32, there is no possibility that the combustion air and combustion exhaust gas will mix. In this way, the combustion air is preheated by heat exchange with the combustion exhaust gas in the air heater 18, and then passed through the swirler.
41 into the combustion chamber 15.

The air preheater 18 according to the present invention described above includes a thin annular plate 3
Since the heat transfer body 30 has a laminated structure, the heat transfer area is large even though it is small, and the heat loss is small. Furthermore, in this air preheater, a bent part is formed in the annular plate that is a component of the heat transfer body, and the fluid passages on the inner and outer circumferential sides are sealed from each other by the engagement of the bent parts, so that the laminated state is maintained. The sealing action is reliable regardless of the elasticity of the combustion air, and combustion air and combustion exhaust gas do not mix, resulting in high heat exchange efficiency.

Note that the present invention is not limited to the above embodiments,
For example, in the embodiment, the inner peripheral fluid passage 3 in the heat transfer body 30
3, and combustion air was made to flow through the outer fluid passage 34, but conversely, combustion air was made to flow through the inner fluid passage 33, and combustion exhaust gas was passed through the outer fluid passage 34. It may also be configured to allow the flow of water.

In addition, in the embodiment, fluid passages 33 and 34 in the heat transfer body 30
Although the fluid passage holes 33a and 34a forming the periphery are closed in shape, they may be cut-out holes. In addition, the present invention can be implemented with various modifications without departing from the gist.

[Effects of the Invention] According to the present invention, the heat transfer area can be increased while reducing the size and heat loss, and the sealing between the fluid passages through which combustion air and combustion exhaust gas flow, respectively, is ensured. An air preheater with high heat exchange efficiency for preheating can be provided.

[Brief explanation of drawings]

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 sectional view showing the configuration of the air preheater in the same embodiment, and FIG. 3 is the same. FIG. 2 is a partially cutaway perspective view showing the configuration of a heat transfer body in the air heater. 1... Expansion cylinder, 2... Expansion piston, 3...
・Compression cylinder, 4... Compression piston, 5... Heater, 6... Regenerator, 7... Cooler, 8.9... Connecting rod, 10.11... Crankshaft, 1
2... Output shaft, 13... Cylinder head, 14...
・Inner insulation material, 15...combustion! , 16... Heat exchanger, 17... Gas nozzle, 18... Air preheater, 19
... Manifold, 20... Connection pipe, 21... Crank to, 22.23... Linear bearing, 24.2
5... Refrigerant piping, 26... Lower insulation material, 27...
Outer heat insulating material, 28... Annular space, 29... Cylindrical case, 30... Heat transfer body, 31... Annular plate, 32...
Bent portions, 33a, 34a...Fluid passage holes, 33...
Inner circumference side fluid passage, 34...Outer circumference side fluid passage, 35.3
6... Fluid passage hole, 37... Upper flange, 38...
...Fluid passage hole, 39...Lower flange, /10...
・Air inlet, 41...Swirler-142...U1 cylinder.

Claims (1)

[Claims] In an air preheater that preheats combustion air introduced into a combustion chamber by heat exchange with combustion exhaust gas, the air preheater includes a case that forms an annular space around the combustion chamber, and a case that is provided in the annular space within the case and that extends in the radial direction. A bent portion protruding toward one surface is formed continuously along the circumferential direction in the middle portion of the bending portion, and a plurality of holes forming fluid passages isolated from each other on the inner and outer circumferential sides of the bent portion. A heat transfer body configured by laminating a plurality of annular plates each having a plurality of annular plates such that their bent portions mesh with each other, and either one of a fluid passage on an inner circumferential side or an outer circumferential side of the bent portions of the heat transfer body. An air preheater comprising means for passing the combustion air through one and means for passing the combustion exhaust gas through the other.