JPH07225012A - Self-ignition type combustion equipment - Google Patents

Abstract

PURPOSE: To keep stable a flame surface and hence avoid a reverse flow of a flame into an inflow region and restrict emission of harmful matter, by disposing a conspicuous lateral cross section expansion portion on a transfer portion between the inflow region and a combustion region for guiding a flow cross section of the combustion region. CONSTITUTION: A self ignition combustor chiefly comprises an inflow region 1 and a combustion region 2 which are arranged in parallel with each other and have the same flow direction. Working gas 7 flowing into a spiral flow formation element 3 and a fuel 5 supplied from a fuel lance 4 cause properly self-ignition respectively, and the fuel 5 is injected from a fuel nozzle 6 and is then discharged as hot gas 10. Herein, there is disposed a sharp cross section expansion section 8 on the transfer section between the inflow region 1 and the combustion region 2 for guiding the flow cross section of the combustion region 2. The transverse expansion section 8 keeps stably a flame surface 9 and hence avoids a reverse flow of a flame from the combustion region 2 to the inflow region 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-ignition type combustor, which is mainly provided with an inflow section and a combustion section, and both sections are arranged side by side and have the same flow direction. Regarding the type of

[0002]

2. Description of the Prior Art How to most easily obtain a stable flame front in a combustion device with a premixing zone and a free opening in the outflow direction towards a downstream combustion chamber. Problems often arise. Various proposals are already known for this problem, but none of them is satisfactory. Exceptions known to date include the means described in EP-A-321809. This known means in terms of flame stabilization, pollutant emissions, also in particular points of the NO _x release and efficiency, and has outstanding characteristics. However, there are also combustion installations for which, for various reasons, it is not possible to use the means disclosed in EP-A-321809. Therefore, in such combustion equipment,
Even if one tries to rely on a diffusion burner and to replenish the premixing zone with swirl formers in the area of the flame front,
As usual, we have no choice but to drive using old technology. That is, in the first case, ie when trying to rely on diffusion burners, one must always be prepared for high NO _x emissions. The emission of this NO _x emission is no longer in line with the laws enacted by the nations, which are of great market importance.
In the second case, i.e. when trying to replenish the premixing zone with a vortex former, especially along the inner wall, despite the fact that the premixing zone is protected by this vortex former.
In other words, flame backflow still occurs along the point where only a small flow velocity is generated. A typical combustion facility in which the above-described technique of preventing backflow of flames is compelled to fail is a combustor designed to be self-igniting. Self-igniting combustors generally have a substantially cylindrical tube into which the working gas flows axially at a relatively high temperature, where it mixes with the fuel supplied by the nozzle, This fuel causes self-ignition. In this case, the thermal aftertreatment of the hot gas is only carried out inside the tube. With such an arrangement, it is already impossible, for space reasons, to incorporate a premixer or provide auxiliary means to prevent flame backflow.
For this reason, in order to compactly install such a combustor between two turbines mounted on one shaft,
The above-mentioned combustion technology, which is attractive in itself, has hitherto been abandoned.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to improve a combustor of the type mentioned at the outset by providing means for flame stabilization and yet to release harmful substances, in particular NO _x emissions, CO emissions. And to provide a combustor in which UHC (unsaturated hydrocarbon) emissions are also minimized.

[0004]

SUMMARY OF THE INVENTION In order to solve this problem, in the arrangement according to the invention, the transition between the inflow zone and the combustion zone leads to a dramatic cross-section which induces a cross-section of the combustion zone. The enlarged part is provided.

[0005]

According to the invention, the abovementioned drawbacks are avoided.

Another advantage of the present invention is recognized in that the stabilization of the flame front is obtained on the basis of the above-mentioned shaping of the combustion zone arranged downstream of the inflow zone.

The flame front is formed at the beginning of the combustion zone.
In this plane, the combustion zone has a dramatic cross-section enlargement. The size of this enlarged cross section also defines the inherent cross section of the combustion zone. During operation, an edge area is created inside the enlarged cross-section that extends radially offset with respect to the cross-section of the inflow area. In this edge area, a vortex separation, or vortex ring, is formed due to the negative pressure created by the flow at this location. This swirl ring provides ring stabilization of the flame front. Such an arrangement is particularly advantageous when the combustion chamber is designed to be self-igniting. That is, such a combustor has a predominantly annular or ring-shaped combustor form, yet has a short axial length and is passed through by working gas at high temperature and high velocity. The circumferential vortex shedding stabilizes the flame front, in which case no additional measures are required to prevent flash backfire. In addition, it is no longer necessary to introduce a flame stabilization blocker into the combustion zone. Due to its geometrical simplicity, the construction of such a combustor is pre-specified to be manufactured in particular from a ceramic material. This provides a great advantage for cooling highly heat-loaded walls, but such combustors can be operated with a minimized cooling air flow. Also,
Such an unobstructed stabilization of the flame front leads to an increase in equipment efficiency, and the utility of such a combustor is also significantly increased.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In the drawings, unnecessary components are omitted for a direct understanding of the present invention. In all the drawings, the same components have the same reference numerals. The direction of flow of the medium is indicated by the arrow.

The combustor shown in FIG. 1 comprises a substantially cylindrical tube. Of course, such a combustor may mainly have the shape of an articulated annular axial or near axial cylinder. Furthermore, such a combustor may consist of a plurality of individually closed combustion chambers arranged axially, generally axially or spirally. Such a combustor is preferably suitable for being operated as a self-igniting combustor. Such a combustor is arranged in the flow direction between two turbines mounted on a shaft. When such a combustor is operated in self-ignition mode, the turbine (not shown) working upstream is designed only for the partial expansion of the working gas 7. This causes this working gas to enter the inflow zone 1 of the combustor at a very high temperature. In such an operation type and the annular arrangement configuration of the combustor, the plurality of fuel lances 4 are distributed and arranged in the circumferential direction of the annular cylindrical body forming the combustor. These fuel lances are for fueling purposes,
For example, they are connected to each other via an annular conduit (not shown). Therefore, this combustor does not have its own burner. That is, the fuel 5 supplied to the working gas 7 by the fuel lance 4 causes self-ignition if the working gas 7 has an inherent temperature such that it can cause fuel-related self-ignition. If the combustor is operated with gaseous fuel, a working gas 7 temperature of about 1000 ° C. must be present in order to cause autoignition. The fuel 5 to be supplied flows through the fuel lance 4 into the fuel nozzle 6 arranged approximately on the axis of the inflow section 1, as described above. This fuel nozzle has a row of supply openings 11 on the end side. These supply openings 11 are arranged annularly along the peripheral surface of the fuel nozzle 6 and are advantageously oriented for optimal mixing for the purpose of fuel supply. The drawing shows the supply of the fuel 5 oblique to the flow direction of the working gas 7. However, it is also possible to arrange such that the supply of the fuel 5 is directed to the flow of the working gas 7, depending on the type of fuel and the type of operation. Immediately upstream of the fuel nozzle 6, a series of swirl-forming elements 3 are provided inside and in the circumferential direction of the inner wall of the inflow zone 1. Advantageously, these swirl-forming elements are formed in the shape of a tetrahedron and are cooled. In this case, the cooling air required to cool the swirl forming element 3 is subsequently added to the working gas 7. This vortex forming element 3 produces a vortex motion. This swirling motion promotes and optimizes the mixing process that takes place downstream, and at the same time creates a counterflow zone or a zone of reduced axial velocity, even in the area of the flame front (discussed below). The inflow zone 1 transitions to the combustion zone 2 after another zone which is kept very short. The transition between the two sections is formed by a radial cross-section enlargement 8 on one side. This enlarged cross section causes a sickle-shaped expansion of the combustion zone 2. In this plane,
A flame front is also formed. In order to avoid flashback of the flame into the interior of the inflow zone 1, the flame surface must be held stable, which is achieved by the cross-section enlargement 8. A flow edge area is formed inside the enlarged cross section 8 during operation. In this flow edge region, eddy current separation occurs due to the negative pressure created at this location. This vortex separation results in stabilization of the flame surface 9 or stabilization of the backflow zone. The hot gas 10 treated in the combustion zone 2 eventually loads a turbine (not shown) working downstream.

FIG. 2 shows another combustor designed to be self-igniting. The enlarged cross section 12 provided in this combustor is symmetrically held on the plane of the flame surface 9.
The radial extension of the cross-section enlargement 12 at the same time defines the flow-through cross section of the combustion zone 2. Inside the expansion area formed by the enlarged cross section 12, the illustrated swirl ring 13 is shown.
Occurs. This vortex ring is oriented in a counterclockwise direction. This swirl ring provides stabilization of the flame surface 9 for the reasons already explained. Compared to the one-sided cross-section enlargement shown in FIG. 1, such an arrangement results in the formation of a relatively narrow arc of the flame surface 9 which covers the entire cross-section of the inflow zone 1.

The embodiment shown in FIG. 3 has an enlarged cross section 14
2 is different from the embodiment of FIG. 2 in that it is formed into an annular trapezoid. That is, in the embodiment of FIG. 3, the expansion is axially narrowed on the side of the combustion zone 2, that is to say the flow-through cross section is reduced. Such cross-sectional reduction is introduced in relation to existing flow parameters. This is the case if a relatively long zone with negative pressure is required, eg for the purpose of stabilizing the flame front 9, or for example the combustion zone 2
This is the case when the cross-section of the flow must be reduced based on the flame stabilizing effect for the purpose of increasing the flow velocity. The swirl ring 13 generally results in an enclosure of the flame front 9 and of the counterflow area, thus providing a stabilization of the combustion taking place there.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a self-igniting combustor consisting of an inflow section and a combustion section.

FIG. 2 is a schematic diagram of a combustor according to another embodiment.

FIG. 3 is a schematic diagram of a combustor according to yet another embodiment.

[Explanation of symbols]

1 inflow area, 2 combustion area, 3 swirl forming element, 4 fuel lance, 5 fuel, 6 fuel nozzle, 7 working gas, 8 cross section enlarged part, 9 flame surface, 10 hot gas, 11 supply nozzle, 12 cross section enlarged Section, 13 Eddy current ring, 14 Enlarged cross section

Claims (6)

[Claims] Claim: What is claimed is: 1. A self-ignition type combustor, which is mainly provided with an inflow section and a combustion section, both sections are arranged side by side, and have the same flow direction. At the transition between the inflow zone (1) and the combustion zone (2), a dramatic transverse cross-section enlargement (8, 12, 14) is provided which guides the cross-section of the combustion zone (2). A self-igniting combustor characterized in that 2. The combustor according to claim 1, wherein the enlarged cross section (12) is formed symmetrically in the radial direction. 3. The cross-section enlargement (14) is formed symmetrically in the radial direction and has a cross-section reduction in the flow direction of the combustion zone (2). Combustor. 4. The inflow zone (1) has at least one fuel lance (4), upstream of which the swirl forming element (3) is provided.
The combustor according to claim 1. 5. The vortex forming element (3) has the shape of a tetrahedron, the vortex forming element (3) being arranged in the circumferential direction of the inflow area (1) through which it flows. Combustor according to claim 4, characterized in that the swirl forming element (3) further narrows the cross-section of the inlet zone (1) in the flow direction. 6. The combustor of claim 1, wherein the combustor has an annular shape.