JPS5812488B2 - hot gas engine combustor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustor for a hot gas engine such as a Stirling engine.

The efficiency of a hot gas engine is determined by the combustion efficiency, Carnot efficiency, indicated efficiency, mechanical efficiency, and auxiliary equipment efficiency as ηcom and ηCAR. ηi
nd, ηMEOH, and ηAuX, the value is the product of these.

That is, ηENGINE=ηcom×ηOAr×ηin
d×ηMBOH×ηAuX.

Of these, combustion efficiency η. om indicates the ratio of the amount of heat given to the engine's working medium gas to the fuel input, and in order to increase the high efficiency of the actual hot gas engine, especially η
.

. It is necessary to improve the

In this case, the amount of heat given to other than the working medium gas of the engine, that is, the heat loss, includes (1) the amount of heat carried away by the exhaust gas, (2
) amount of heat released from the furnace outer wall, (3) amount of heat stored in the furnace body, etc.

Of these, the temperature of the engine's heating pipe needs to be maintained at 600 to 700 degrees Celsius to increase engine efficiency, so the atmospheric temperature inside the furnace will inevitably be high. In this case, the combustion efficiency becomes extremely low.

For example, when methane gas is combusted and released into the atmosphere at an exhaust gas temperature of 700°C, the exhaust gas heat loss is 38 at the theoretical mixing ratio.
%, and when the excess air rate is 30%, it reaches 43%.

Therefore, in order to increase combustion efficiency, it is necessary to reduce exhaust gas heat loss as much as possible, and conventional efforts have been made to increase combustion efficiency by heating combustion air with exhaust gas.

For example, in JP-A-53-92926, an air supply passage and an exhaust gas passage formed by concentric tube assemblies are arranged on the side of the combustion chamber, but according to this configuration, the exhaust gas is not discharged directly upward. , the draft effect cannot be used effectively, and it becomes necessary to use a blower fan with high static pressure to supply combustion air, thus increasing the power consumption of the blower fan and reducing the efficiency of the hot gas engine. There are drawbacks.

Furthermore, since the structure of the heat exchanger is a simple concentric tube assembly, there is also the disadvantage that the external size is very large in order to obtain the necessary heat transfer area.

Therefore, in order to solve the above-mentioned drawbacks, the present invention provides a downward-facing burner in the center of the upper part of the combustion chamber in which the heating pipe is installed in the bottom, and an air supply pipe that surrounds the burner. and forming an exhaust gas passage with an air manifold so as to surround the air supply pipe at equal intervals outside the air supply pipe, and the air supply pipe and the air manifold are arranged in the exhaust gas passage. The structure is characterized by the provision of a large number of heat exchange pipes with fins that communicate in the radial direction, and its purpose is to make the most effective use of the draft effect of exhaust gas from the combustion chamber, thereby reducing the To miniaturize a combustor and a blower fan by creating a flow of exhaust gas and effectively preheating combustion air.

Embodiments of the present invention will be described in detail below based on the accompanying drawings.
1 is a heat insulating material forming a cylindrical combustion chamber 2, 3 is a heating pipe constructed at the bottom of the combustion chamber 2, 4 is an exhaust gas outlet above the combustion chamber 2, and 5 is a concentric circle constructed above the combustion chamber 2. A shaped air manifold 6 is a blower fan for blowing air to the air manifold 5.

7 is an exhaust gas passage formed between the air manifold 5 and an air supply pipe 10 whose upper end is closed and whose lower end is directed toward the combustion chamber 2 and is open toward the combustion chamber 2;
It continues above the exhaust gas outlet 4.

A fuel supply pipe 8 is inserted into the air supply pipe 10, and a downwardly directed burner 9 is attached to the tip of the combustion supply pipe 8.

11 is a mixing plate configured at the tip of burner 9,
12 is a heat exchange pipe communicating between the air manifold 5 and the air supply pipe 10, and this heat exchange pipe 12
A large number of fins are arranged so as to traverse the exhaust gas passage 7 in the radial direction, and fins are attached to the outside of the fins to improve the heat absorption effect.

The present invention is constructed as described above, and fuel is supplied from the combustion supply pipe 8 to the burner 9. On the other hand, air for combustion is sent into the air manifold 5 by the blower fan 6. is a large number of heat exchange pipes 1
The fuel is fed into the air supply pipe 10 through the air supply pipe 2, moves downward through the air supply pipe 10, and mixes with the fuel ejected from the burner 9.

When the burner 9 is ignited, its flame heats the heating pipe 3 within the combustion chamber 2.

The heating medium in the heating pipe 3 is heated by this flame (combustion gas), and the exhaust gas is reversed in the combustion chamber 2 as shown by the arrow in FIG. It enters the combustor, rises here, and is discharged outside the combustor.

Combustion air sent into the air manifold 5 by the blower fan 6 passes through the heat exchange pipe 12 from the air manifold 5 and is heated by the exhaust gas rising in the exhaust gas passage 7 while entering the air supply pipe 10. (preheated).

As described above, in the present invention, since the exhaust gas passage 7 is formed straight above the combustion chamber 2, the combustion chamber 2 and the exhaust gas outlet 4 are
The draft effectively acts on the exhaust gas rising inside the exhaust gas passage 7.

Furthermore, since fins are attached to the heat exchange pipe 12 to enhance the heat absorption effect, the heat exchange pipe 12 can be shortened.

As a result, it is possible to lower the static pressure of the blower fan 6, and therefore the static pressure of the blower fan 6 can be small, and the auxiliary power efficiency of the hot gas engine can be significantly increased.

Further, in the present invention, a large number of heat exchange pipes 12 for preheating the air are provided to cross the exhaust gas passage 7, and since fins are attached to the heat exchange pipes 12, the air is preheated. This heat exchange pipe 12 is sufficient for this purpose.

Therefore, even if the combustion air is preheated using exhaust gas, the preheating mechanism does not become large, and the outer shape of the combustor can be made compact.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a combustor according to the present invention, and Fig. 2 is a sectional view of a combustor according to the present invention.
-A' line sectional view. 1...Stomach insulation material, 2...Combustion chamber, 3...Heating pipe, 4...
→Exhaust gas outlet, 5...Air manifold, 6...Blower fan, 7...Exhaust gas passage, 8...Fuel supply pipe, 9...Burner, 10...Air supply pipe, 11...Mixing plate, 1
2...Multiple heat exchange pipes with fins.

Claims (1)

[Claims] 1. At the top of a combustion chamber with a heating pipe installed in the bottom, a downward-facing burner is provided in the center, and adjacent surrounding air supply pipes are arranged to surround the burner, and air supply pipes are arranged at equal intervals on the outside of the air supply pipe. forming an exhaust gas passage with an air manifold so as to surround the air supply pipe, and in the exhaust gas passage, a number of heat exchange pipes having fins are provided in which the air supply pipe and the air manifold communicate with each other in the radial direction. A combustor of a hot gas engine comprising: