JPH0819876B2 - Heating device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heating device used in an external combustion engine or the like, and more particularly, to an electrical insulator for a flame detection electrode and an ignition discharge electrode, one end of which faces a combustion part. The present invention relates to a heating device that protects from heat.

[Conventional technology]

Figure 3 shows, for example, International Conference Proceedings 4th ICSE, 1988 11
It is sectional drawing which shows the heating device of the conventional external combustion engine shown by the moon, PP.7-12, 1 is a combustible substance which is a fuel, and when burning this combustible substance, it is a sectional view. Combustion part that takes in combustion-supporting substances such as air and causes combustion, 2
Is a fuel nozzle that is attached to a part of the chamber wall of the combustion unit 1 and injects fuel. 3 is a heat exchanger that is provided in the combustion unit 1 to obtain the heat of the external combustion engine. 4 is a container of the combustion unit 1. Burner tiles 5 forming a part of the chamber peripheral wall are air guide blades for swirling a combustion-supporting substance such as air to hold a flame, and the fuel nozzle 2 and the air guide blades 5 constitute a burner. Has been done. Reference numeral 6 denotes an ignition discharge electrode provided near the fuel nozzle 2, 7 denotes a flame detection electrode provided near the fuel nozzle 2, and 8a and 8b electrically connect the flame detection electrode 7 and the ignition discharge electrode 6 from the surroundings. Electrical insulators to insulate, 9
Is a flame detection circuit electrically connected to the flame detection electrode 7 and the fuel nozzle 2 used as an electrode on the ground side, 10 is an electrode introduction pipe for guiding the electrodes 6, 7 to the combustion section 1, and 11 is air for the combustion section 1. An air flow path to be introduced, 12 is a combustion exhaust gas flow path for discharging exhaust gas which is a combustion exhaust substance burned in the combustion section 1, 14 is a preheating section, and this is a fin for connecting the air flow path 11 and the combustion exhaust gas flow path 12 It is located outside the combustion section 1 via a member 13 such as a partition wall that allows heat transfer, and preheats the air with the heat retained by the combustion exhaust gas. Reference numeral 15 is an internal heat insulating material that is provided between the preheating portion 14 and the combustion portion 1 to block heat, and 16 is an external heat insulating material that is provided around the outer periphery of the preheating portion 14 and serves as a heat insulating layer.

Next, the operation will be described. First, the fuel ejected from the fuel nozzle 2 to the combustion section 1 is mixed with the air swirled by the air guide vanes 5 provided around the fuel nozzle 2 and burned. At this time, ignition is performed by the ignition discharge electrode 6 provided near the fuel nozzle 2. Further, confirmation of ignition is performed by checking the fuel nozzle 2 and the flame detection electrode 7
It is performed by applying a voltage between them and detecting the electric resistance (several MΩ) of the flame existing between them by the flame detection circuit 9. If there is no flame, the electric resistance between the two electrodes is very large, the same as the insulation resistance of air.
It becomes 0MΩ or more. During the heating operation, the flame detection circuit 9 is always
The presence or absence of a flame is checked.

The combustion gas, after giving heat energy to the heat exchanger 3 as shown by a dashed arrow in the drawing, becomes a combustion exhaust gas and flows into the preheating unit 14. The combustion exhaust gas in this state is
It still retains about 30% of the heat of combustion. Most of this heat is recovered by the air (solid arrow) passing through the air flow path via the member 13 capable of transferring heat when the combustion exhaust gas passes through the combustion exhaust gas flow path 12. In this figure,
The preheating section 14 is of a counterflow type with good heat recovery efficiency.

As described above, in the external combustion engine such as the Stirling engine, in order to improve the thermal efficiency, the heat is recovered from the combustion exhaust gas after the combustion heat is applied to the heat exchanger 3 to the combustion air. Air temperature after (preheating) is approximately 750 ° C
Rise to a degree. Therefore, the temperature in the vicinity of the air guide vane 5 also rises to the same temperature. Further, the temperature of the heat exchanger 3 is also raised to a high temperature (about 700 ° C.) close to the upper limit temperature of use of the material in order to increase the thermal efficiency.

[Problems to be Solved by the Invention]

Since the conventional heating device is configured as described above,
Electrical insulator 8 for ignition discharge electrode 6 and flame detection electrode 7
Since a and 8b are provided in each electrode introduction pipe 10 and on its extension line, convective heat transfer from preheated air in the vicinity of the fuel nozzle 2 and heat conduction from the air guide vanes 5 inside the external heat insulating material 16 are performed. And heat radiation from the heat exchanger 3 respectively, the temperature becomes high, the electrical insulation resistance decreases, and at the time of re-ignition after warming up, a current flows through the insulator 8a of the ignition discharge electrode 6 and at a predetermined position. In some cases, it does not discharge and does not re-ignite, and after warming up, the electric insulation resistance of the insulator 8b also becomes the same level as the electric resistance of the flame in the flame detection electrode 7,
Even if there is no flame, there is a flame and the flame detection circuit 9
There was a problem such as erroneous judgment.

The present invention has been made to solve the above problems, and an object thereof is to obtain a heating device capable of performing reliable reignition and reliable flame detection.

[Means for solving the problem]

In the heating device according to the present invention, at least one of the first electric insulator and the second electric insulator that electrically insulates the flame detection electrode and the ignition discharge electrode from the surroundings is covered with a heat insulating layer that covers the combustion portion. Outside of the heat insulating layer, and at a position outside the extension line of the electrode introducing pipe that communicates with the inside and outside of the heat insulating layer.

[Action]

The first electric insulator and the second electric insulator in the present invention are provided outside the heat insulating layer which is less susceptible to convective heat transfer by preheated air, heat radiation from a heat exchanger and the like and heat conduction from air guide vanes and the like. Since it is installed away from the electrode introduction tube, the temperature rise after warming up can be suppressed slightly. Therefore, while maintaining a sufficiently high electrical insulation resistance, flame detection by the desired flame detection electrode is possible. And, it is possible to perform stable and highly sensitive ignition discharge by the discharge electrode for ignition.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 6A and 7A are L-shaped ignition discharge electrodes and flame detection electrodes, one end of which faces the inside of the combustion section 1, 8c is a second electric insulator, 8d is a first electric insulator, and 10A. Is an electrode introduction pipe, which is commonly used for introducing the ignition discharge electrode 6A and the flame detection electrode 7A, and the outer diameter thereof is the same as the inner diameter di of the air guide vane 5. The electric insulators 8c, 8d of the ignition discharge electrode 6A and the flame detection electrode 7A are outside the outer heat insulating material 16 as a heat insulating layer and are outside the extension line of the electrode introducing pipe 10A, and the inner diameter di It is installed at a position with a larger diameter than. Reference numeral 18 is a cover that supports the first electric insulator 8d and the second electric insulator 8c outside the external heat insulating material 16. Since the other configurations are the same as those of the conventional example, the duplicated description will be omitted.

Next, the operation will be described. The basic operation of combustion is the same as in the conventional example. In the combustion operation as described above, since the electric insulators 8c and 8b of the ignition discharge electrode 6A and the flame detection electrode 7A are installed outside the external heat insulating material 16 as shown in the figure, convection from the preheated air is performed. Heat transfer due to heat transfer and heat conduction from the air guide vanes 5 is significantly reduced. Further, since each of these insulators 8c, 8d is installed at a position whose diameter is larger than the inner diameter di of the air guide vane 5, the view factor between the heat exchanger 3 and the insulator 8 becomes very small, Heat exchanger 3
The effect of heat radiation from Therefore, there is almost no decrease in the electrical insulation resistance due to the heat of the electrical insulators 8c and 8d,
Flame detection by the flame detection circuit 9 and re-ignition after engine warm-up can be reliably performed.

FIG. 2 is a vertical sectional view showing another embodiment of the present invention. This is a heat insulating material 17 inside the electrode introduction tube 10A electrode 6A,
It is inserted in a state of being floated from 7A, whereby convective heat transfer from preheated air and heat radiation from the heat exchanger 3 can be cut off almost completely, so that the flame detection and re-ignition can be performed more reliably. Can be made.

In the above embodiment, the case where both the ignition discharge electrode 6A and the flame detection electrode 7A are thermally insulated has been described.
Only one of them may be thermally insulated.

EFFECT OF THE INVENTION As described above, according to the present invention, at least one of the first electric insulator and the second electric insulator is outside the heat insulating layer and outside the extension line of the electrode introducing tube. Since it is configured to be provided at a position deviated in the direction, each of these electrical insulators should receive only a small amount of heat transfer from high temperature parts such as the combustion part, convection heat transfer, and heat radiation. Therefore, there is an effect that a reliable re-ignition after warming up and a reliable flame detection can be performed.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a heating device according to an embodiment of the present invention, FIG. 2 is a vertical sectional view showing a heating device according to another embodiment of the present invention, and FIG. 3 is heating of a conventional external combustion engine. It is a longitudinal cross-sectional view showing an apparatus. 1 is a combustion part, 2 is a fuel nozzle, 6A is a discharge electrode for ignition, 7A
Is a flame detection electrode, 8d is a first electric insulator, 8c is a second electric insulator, 9 is a flame detection circuit, 10A is an electrode introduction pipe, and 16 is a heat insulating layer (external heat insulating material). In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A fuel nozzle for injecting fuel, a combustion section for combusting the fuel with air, a heat insulating layer provided so as to cover the combustion section, and a contact section for contacting flames in the combustion section. A flame detecting electrode, a flame detecting circuit electrically connected to the flame detecting electrode and the fuel nozzle, and a first electrically insulating the flame detecting electrode from the surroundings.
Electrical insulator, an ignition discharge electrode provided adjacent to the fuel nozzle, a second electrical insulator electrically insulating the ignition discharge electrode from the surroundings, and inside and outside the heat insulating layer. In a heating device which is provided with an electrode introduction tube in which the flame detection electrode and the ignition discharge electrode are arranged, at least one of the first electrical insulator and the second electrical insulator is provided in the heat insulating layer. The heating device is installed outside of the above and at a position deviated from the extension line of the electrode introduction pipe in the outward direction.