JPS6220372B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion device for a Stirling engine.

Stirling engine combustion devices are required to satisfy the conditions of high combustion chamber volume load (high load combustion) and wide combustion load. High-load combustion means that in the volume filled with the working gas of the Stirling engine, an increase in the dead volume other than the scavenging volume of the piston is a direct cause of reducing the thermal efficiency of the engine, and the heat exchanger on the high temperature side The internal volume of the high-temperature heat exchanger (high-temperature heat exchanger) needs to be as small as possible, so the space enclosed by the cylindrical or cage-shaped high-temperature heat exchanger assembly naturally becomes narrower, and therefore, that space must be burned out. In order to create a combustion chamber, it is necessary to shorten the flame and complete combustion under the conditions that require the largest amount of combustion, and the combustion chamber volume load is 1×10 ⁷ Kcal/
This refers to the need to satisfy hr・m ³ .

Next, a wide combustion load means that when a Stirling engine is actually used as a power engine, it is necessary to quickly change the combustion load according to the load condition required of the engine, and the minimum combustion amount / This refers to the need to satisfy the maximum combustion amount (turndown ratio) of 1/20.

There is a need for a combustion device that satisfies the above two conditions at the same time and uses light oil, which has many advantages as a fuel and has lower volatility than gasoline and does not contain additives, in a Stirling engine.

The above conditions cannot be met with the combination of conventional pressure spray nozzles, two-fluid nozzles, and combustors. The biggest reason is that with fuels such as light oil, which have lower volatility than gasoline, simply burning the oil particles by making them finer will result in a slow combustion rate, making it impossible to achieve high-load combustion with a short flame. In other words, combustion that satisfies the combustion chamber volume load of 1×10 ⁷ Kcal/hr·m ³ cannot be achieved. The next reason is that with a pressure spray nozzle, in principle the minimum pressure required to make oil particles fine is 5 kg/
cm ² (G), and since the flow rate changes in proportion to the square of the pressure, a pressure ratio of 1:400 is required to obtain a turndown ratio of 1/20, which is actually impossible with a single nozzle. It is possible. In addition, the atomization performance of a two-fluid atomizing nozzle is determined by the air flow velocity, and the average oil droplet diameter is inversely proportional to the air flow velocity, so a speed of 200 m/g or more is required to produce the fine particles necessary for combustion. is required, and the volumetric flow rate ratio (air/light oil) is 5000.
This amount is 30% of the total amount of combustion air.
It is equivalent to consuming a large amount of high-pressure air, and
In order to obtain a turndown ratio of 1/20, it is necessary to change the amount of air accordingly, which is extremely complicated and consumes a large amount of power, making it practically impossible to apply. As another conventional method, if light oil is vaporized in advance and then combusted using a combination of a gas burner and a combustor, it is possible to satisfy high-load combustion and a wide range of combustion loads. However, it requires another heat source for vaporization, it takes time to vaporize light oil beyond ignition, which makes engine starting difficult, and it is difficult to vaporize light oil, which has lower volatility than gasoline. Temperature control is required during vaporization, and the temperature is as high as 170 to 200°C, and furthermore, it is difficult to provide vaporization capacity that corresponds to a turndown ratio of 1/20. In other words, the equipment is complicated, the startability is poor, and the vaporization section outside the furnace is highly dangerous.

Therefore, the present invention solves all of the above-mentioned problems of the conventional technology, and satisfies both of the specifications required for the Stirling engine: (1) high load combustion, and (2) wide range of combustion loads, with an extremely simple structure. The object of the present invention is to provide a combustion device for a Stirling engine.

One embodiment and other modified embodiments of the present invention will be described below with reference to the accompanying drawings. First, the configuration of an embodiment of the present invention will be explained based on FIGS. 1 and 2. Reference numeral 1 denotes an injection nozzle, and as shown in detail in FIG. It has a nozzle throat section 7 for accelerating the atomizing air and a nozzle throat section 7 for accelerating the atomizing air at the downstream end 6, and a nozzle throat section 7 for accelerating the atomizing air. The resonant box 9 has a concave portion inside at a position where the atomizing air mixed with liquid fuel and accelerated collides with the resonant box 9. Furthermore, 10 is a support rod provided on the outer peripheral part 4,
It has the resonance box at its tip and forms a sound wave field 11 inside it.

As shown in detail in FIG. 1, the injection nozzle 1 includes an atomizing air supply system consisting of a compressor 12 and a pipe 13, a fuel tank 14, and a fuel pump 1.
5, a fuel supply system consisting of a regulating valve 16 and a pipe 17. The passage 3 of the injection nozzle 1 communicates with a tube 13, and the passage 5 of the injection nozzle 1 communicates with a tube 17.

Furthermore, a blower 18, a regulating valve 19 and a duct 20
A combustion air supply system consisting of a combustion air supply system is connected to the inlet 22 of the preheater 21. The injection nozzle 1 is attached to this preheater 21. The preheater 2
1, flow paths 23 and 24 are provided. Furthermore, the preheater 21 has a space 26 in which the air coming out of the air outlet 25 can circulate around the injection nozzle 1 . The combustor 27 also includes an air inlet 28,
29 and a spark plug 30. The combustion chamber 31 is a space surrounded by a plurality of expansion cylinders 32 and a plurality of heater pipes 33 connected to the expansion cylinders 32 and arranged in a cylindrical shape. Further, a furnace 35 is made of a heat insulating material 34, and combustion gas is discharged to the outside from a plurality of combustion gas exhaust pipes 36. 37 is an inlet, and 38 is an outlet.

Next, another modified embodiment of the above-described injection nozzle 1 will be described based on FIG. 3. This injection nozzle 1
is provided with fins 4a on its outer peripheral portion 4. This fin 4a may be provided only within the preheater 21. The other points are exactly the same as the configuration of the injection nozzle described above, so the explanation thereof will be omitted.

Further, another modified embodiment of the atomizing air supply system and fuel supply system described above will be described based on FIG. 4. A switching valve 39 is provided between the pipes 13 and 17. This switching valve 39 allows communication between the pipe 17 and the rear pipe 17 at the start of combustion and at the time of combustion,
When combustion is stopped, the pipe 13 and the rear pipe 17 are designed to communicate with each other. Further, the compressor 12 is configured to operate for a certain period of time after combustion is stopped. The rest of the configuration is exactly the same as the configuration of each system described above, so the explanation thereof will be omitted.

In the above configuration, combustion air is supplied from the blower 18, the regulating valve 19, and the duct 20, and is blown out from the inlet 22 of the preheater 21 through the flow paths 23 and 24 to the air outlet 25. On the other hand, air for atomization is supplied to the injection nozzle 1 through the compressor 12 pipe 13.
Light oil, which is fuel, is supplied through a fuel tank 14, a fuel pump 15, a regulating valve 16, and a pipe 17. When the engine starts, the light oil that is the fuel is not heated, and the atomized oil particles are injected into the combustor 27 by the single injection nozzle 1, and the combustion air is blown out from the air inlets 28 and 29. The mixture is mixed and ignited by the spark plug 30. From then on, fuel and combustion air are adjusted manually or automatically by adjusting valve 1 depending on the required output (load) of the engine.
6, 19. There is no need to change the atomizing air even if the fuel flow rate changes. The flame is in kiln 3
The combustion chamber 31 is formed in the combustion chamber 31 in the heater pipe 33 and the expansion cylinder 32 and supplies thermal energy to the working gas in the heater pipe 33 and the expansion cylinder 32 mainly by radiation heat transfer and convection heat transfer.
Furthermore, even after supplying heat to the working gas, the combustion gas passes through the combustion gas discharge pipe 36 from the inlet 37 to the outlet 38 while maintaining a temperature of 800 to 900°C. At this time, the combustion air passes through the outside of the exhaust pipe 36, receives heat from the combustion gas, and the air heated to 600 to 700°C flows from the preheater outlet 25 into the space 26.
The injection nozzle 1 is heated.

The role of the injection nozzle 1 will be explained based on FIG. 1. At the time of startup, the atomizing air is accelerated by the nozzle throat section 7 and collides with the resonance box 9, creating a sonic field 11, and the light oil that is the fuel is made into fine particles here and is combined with the atomizing air. mixed.
These fine particles have a small particle size and, as mentioned above, are easily ignited and do not cause mistakes. Next, after ignition, light oil for combustion enters from the pipe 17,
When reaching the passage 5, the outer circumference 4 of this injection nozzle 1
As described above, the fuel is exposed to preheated air at 600 to 700°C, and part or all of the fuel is vaporized before passing through the passage 5 and reaching the pores 8. This vaporized fuel is mixed with the combustion air at a high speed and extremely uniformly in the sonic field 11 ejected into the combustor 27, and as a result, the flame in the combustion chamber 31 becomes short and the liquid fuel is combusted. It has a combustion speed that cannot be reached by other methods, and complete combustion takes place in the furnace 35.
The above operation is satisfied even when a large amount of fuel is supplied at the maximum output of the engine, and is performed satisfactorily over the entire required output range of the engine.

Next, the operation of another modified embodiment of the injection nozzle 1 of the present invention will be explained. The outer peripheral part 4 of this injection nozzle 1
The fins 4a attached to the fins 4a are attached inside the preheater 21, and the heat from the preheated air is transferred to the fins 4a.
It is transmitted to the light oil of fuel through a, and vaporizes some or all of it.

Furthermore, the operation of another modified embodiment of the air supply system and fuel supply system will be explained based on FIG. In the case of combustion, the switching valve 39 allows the pipe 17 to communicate with the injection nozzle 1 to perform the above-described operation.
When combustion is stopped, the switching valve 39 allows the rear pipe 17 and the pipe 13 to communicate, and the injection nozzle 1 and the fuel pump 15 to communicate with each other.
The fuel circuit by the pipe 17 connecting the two is cut off. Therefore, the fuel remaining in the injection nozzle 1 is blown away by the atomizing air sent by the compressor 12, which continues to operate for a certain period of time even after combustion has stopped.

As described above, according to the present invention, air for circulating preheated air is provided around the injection nozzle, a passage for liquid fuel is provided on the outer periphery of the injection nozzle, and atomizing air mixed with fuel is provided. Since a resonant box with a sonic field inside is provided at the collision position, the light oil, which is liquid fuel, receives heat from the preheated air within the injection nozzle, and part or all of it evaporates. Therefore, no evaporation process of liquid particles is required. Furthermore, the sonic field generated by the resonance box causes the evaporation to diffuse and mix with air, and the speed of this is extremely high. Furthermore, this allows the entire combustion process to be very short and the length of the flame to be very short. As a result, combustion with a combustion volumetric heat load of 1×10 ⁷ Kcal/hr·m ³ can be performed, which allows the combustion chamber to be reduced to 1/10 of the conventional size.

Due to the structure of the present invention, it is only necessary to make the particles fine at the time of initial ignition. Even in that case, since the particles are made fine by the sonic field, there is no need to make the diameter of the pores of the injection nozzle small, and the atomization of the particles becomes fine. Low pressure and small amounts of air are required for chemical conversion. Furthermore, as mentioned above, since the fuel flowing out from the injection nozzle has already been vaporized, there is no need to adjust the fuel supply pressure and atomization air pressure to make the particles finer, so the turndown ratio is 1. /20 can be easily achieved.

In addition, according to the present invention, by providing the fins on the outer periphery of the injection nozzle, the heat receiving area from the preheated air is increased, so that it can be used even when the preheated air temperature is relatively low and when the nozzle holder part is short. Also,
It is possible to have a sufficient effect of vaporizing the fuel.

Further, according to the present invention, when the fuel is stopped, the fuel circuit connecting the injection nozzle and the fuel pump is cut off, and at the same time, the circuit is switched so that the fuel remaining in the injection nozzle is blown away by the atomizing air. By installing a switching valve, there is no risk that the pores of the injection nozzle will be clogged by tar generated when the fuel accumulates in the injection nozzle and gradually cools down when combustion stops. .

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing one embodiment of the combustion device of the Stirling engine of the present invention, Fig. 2 is an enlarged central vertical sectional view of the injection nozzle in Fig. 1, and Fig. 3 shows another modified embodiment of the injection nozzle. FIG. 4 is a pipe diagram showing another modification of the atomizing air supply system and fuel supply system in FIG. 1. 1: Injection nozzle, 2: Central axis, 3, 5: Passage, 4: Outer periphery, 9: Resonance box, 11: Sound wave field, 1
2: compressor, 13, 17: pipe, 14: fuel tank, 21: preheater, 26: space, 27: combustor, 35: kiln.

Claims (1)

[Claims] 1. In a Stirling engine combustion device in which an air preheater is attached to the upper part of the kiln and an injection nozzle extends into the air passage of the air preheater, a space is provided around the injection nozzle for preheated air to swirl. In addition, passages for atomizing air and fuel are provided in the central axis and outer circumference of the injection nozzle, respectively, and a resonant box having a sound wave field is provided inside the tip of the injection nozzle. Device.