JPS6259306A - Ultrasonic wave burner - Google Patents

Abstract

PURPOSE:To improve the capability to hold a flame by supplying a part of all of the combustion air so that its central axis intersects with the central axis of an atom ized fuel flow and providing as needed a flame-holding mechanism at the tip end of a jet nozzle. CONSTITUTION:A throat section 3 which encloses the tip edge section of an ultrasonic wave jet nozzle 1 is provided at a combustion air passage 4 which is concentrically formed between a housing 8 and an ultrasonic wave jet nozzle 1 and at the transition section to a combustion chamber. A part of the combustion air is led to a combustion chamber as the central axis of the combustion air is bent in the flow passage by the throat section 3, and the combustion air is mixed with an atomized fuel flow 11 and burnt. The combustion air except the assisting air passes the outside of the throat section 3 and flows into a combustion chamber 10. Further, swirlers 5 and 5' are provided as needed at the inside and outside of the throat section 3 respectively. A flame-holding plate 7 is fixed to the throat section 3 or a housing 8 in the fashion that a flame-holding plate 7 faces the tip edge section 2. With this arrangement the mixing characteristics of the atomized fuel and the combustion air can be improved and the flame holding performance is also improved and at the same time it is possible to reduce the amount of the atomized fuel attaching to the wall faces.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic combustion device, and more specifically to an ultrasonic combustion device that uses an ultrasonic vibrator having an edge portion at one end on the combustion chamber side. ) Injection nozzle for gas turbine (2) This invention relates to an ultrasonic combustion device suitably applied as a burner for industrial, commercial, and household boilers, heating furnaces, and heaters.

BACKGROUND OF THE INVENTION For the various combustion devices mentioned above, pressure atomization burners or liquid atomizers have traditionally been used to atomize, or atomize, liquid fuel. In place of such pressure spray burners or liquid sprayers, various injection nozzles using ultrasonic waves have also been tried and used in some cases.

The present applicants have proposed an ultrasonic injection nozzle that improves various drawbacks of the injection nozzle used in the conventional spray burner or liquid atomizer, and the conventional ultrasonic injection nozzle (Japanese Patent Application No. 59-77572). (see ). This ultrasonic injection nozzle has an elongated vibrator connected to one end with an ultrasonic vibration generation stage and an edge portion at the other end, and a liquid is applied to the edge of the vibrator. This is an ultrasonic jet nozzle that supplies liquid and atomizes the liquid. This ultrasonic jet nozzle achieves a large capacity, which was previously considered impossible, by adopting a novel structure called a vibrator with an edge section. Although the present invention relates to an ultrasonic combustion device using this ultrasonic injection nozzle, there have been no reports of this type of use in the past.

Problems to be Solved by the Invention The above-mentioned ultrasonic jet nozzle made by the present applicants has made it possible to increase the capacity, which was considered impossible in the past, but the biggest drawback is that the jetting speed of liquid particles is slow. It is. Therefore, when used as a combustion device, the jetting speed of the atomized fuel is low, so there is a tendency for the atomized fuel to be insufficiently mixed with combustion air. The present invention relates to a combustion device in which the mixing characteristics of atomized fuel and combustion air are improved in the ultrasonic combustion device using the ultrasonic injection nozzle according to the prior invention.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an ultrasonic combustion device with improved mixing characteristics of atomized fuel and combustion air. Another object of the present invention is to provide an ultrasonic combustion device with improved flame holding performance. Another object of the present invention is to provide an ultrasonic combustion device that can reduce the adhesion of atomized fuel to a wall surface due to the generation of vortices near the tip of an injection nozzle.

Means for Solving the Problems The above aspects are achieved by the ultrasonic device according to the present invention. To summarize, the present invention includes an elongated vibrator having an ultrasonic vibration generating means connected to one end and an edge portion at the other end; In an ultrasonic combustion device including an ultrasonic injection nozzle having a built-in supply passage and a combustion air passage provided outside the ultrasonic injection nozzle, part or all of the combustion air is guided to the fuel spray stream at the tip of the edge part. The present invention is characterized in that it includes a flow path changing means for changing the combustion direction, and a flame stabilizing mechanism is provided in the combustion area at the tip of the edge portion, if necessary. The ultrasonic combustion device according to the present invention will be explained in detail with reference to the drawings.

FIG. 2 shows an embodiment of the present invention in which part of the combustion air is used as assist air. FIG. 3 shows an embodiment in which all of the combustion air is used as assist air. Figures 4 and 5 show the actual state in which a flame holding mechanism (a flame holding plate is used in the figure) is additionally installed, and the configurations without the flame holding mechanism are shown in Figures 2 and 5, respectively. Same as Figure 3.

The simplest configuration of a combustion device using a conventional spray nozzle is shown in FIG. In FIG. 2, the ultrasonic combustion device 9 includes a generally cylindrical housing 8 so as to surround the ultrasonic injection nozzle 1.

A concentric space formed between the housing 8 and the ultrasonic injection nozzle 1 forms a combustion air passage 4 . A throat portion 3 is disposed at a transition portion between the combustion air passage 4 and the combustion chamber so as to surround the tip edge portion 2 of the ultrasonic injection nozzle 1. The throat part 3 has a generally annular shape, and a part of the combustion air is guided into the combustion chamber 10 while the flow path center axis is bent inward inside the throat part 3, and mixed with the fuel spray flow 11. , to burn. In the present invention, the air used to improve the mixing of fuel and air is referred to as assist air.

Combustion air other than assist air passes through the passage outside the throat portion 3 and flows into the combustion chamber 10. Inside the throat part 3, the outside passage lj is equipped with a swirler, 5,5'' as necessary.
is installed to give a swirling flow to the combustion air and create a fuel spray flow 11.
Promote mixing with. Flame holding plate 7 in Figures 4 and 5
is fixed to the throat portion 3 or the housing 8 so as to face the tip end portion 2 . Other flame holding mechanisms may be used in place of the flame holding plate. The flame holding mechanism has two purposes. One is to reduce the chance of misfire in the vicinity of the tip edge portion 2 by heat radiation from the flame holding mechanism, and to facilitate re-ignition even if a misfire occurs. Another purpose is that the naked flame mechanism acts as a baffle to promote turbulence in the combustion zone and to reduce the generation of small-area vortices in the combustion zone 6 at the tip of the injection nozzle. These small vortices tend to occur in the area circled in Figure 4, and are the cause of the adhesion of atomized fuel that remains after being completely burnt, or the adhesion of soot due to incomplete combustion. It has become. With such a configuration, it is possible to obtain good combustion with a stable flame shape that is comparable to that of ordinary industrial forced draft burners.

Effects of the Invention As explained above, by supplying part or all of the combustion air so that the central axis of the flow intersects with the central axis of the fuel spray flow, the mixing of fuel and air is promoted, and as a result, the flame shape is improved. It is possible to provide an ultrasonic combustion device that provides stable, consistent and good combustion.

Furthermore, by arranging a flame holding mechanism at the tip of the injection nozzle as necessary, it is possible to provide an ultrasonic combustion device with improved flame holding performance and reduced soot adhesion in the combustion area of the tip. .

[Brief explanation of drawings]

FIG. 1 is an example of a combustion device using a conventional spray nozzle. 2 to 5 are cross-sectional views of embodiments of the ultrasonic combustion device according to the present invention. 1: Ultrasonic injection nozzle 2: Tip edge portion 3: Throat portion 4: Combustion air passage 5.5-: Swirler 6: Tip combustion area 7: Flame holding plate 8: Housing 9: Ultrasonic combustion device 10: Combustion chamber 11: Fuel spray flow

Claims (1)

[Claims] In an ultrasonic combustion device including an ultrasonic injection nozzle using an elongated ultrasonic vibrator having an edge portion at one end of the side where liquid fuel is injected, and a combustion air passage provided around the outer periphery of the ultrasonic injection nozzle. An ultrasonic combustion apparatus characterized in that a flow path changing means for guiding part or all of the combustion air to the tip of the edge portion and, if necessary, a flame stabilizing mechanism provided in the combustion region at the tip of the edge portion.