Burner with protection element for ignition electrodes

Background of the Invention

The invention relates to a burner with an igniter and at least one ignition electrode, particularly to such. For installation in a burner of a gas turbine

A trained as a pilot Boilers with an igniter and leading to the igniter ignition is for example in <patcit id="pcit0001" dnum="EP0193838B1"><text>EP 193 838 B1 0</text></patcit> described. The igniter has the task to ignite the fuel. The ignition electrodes are externally attached to the pilot burner and parallel to its longitudinal axis. The fuel feed is located in the interior of the pilot burner and terminates in fuel discharge orifices. The ignition electrodes forming in the fuel outlet openings and ignite the fuel exiting there by means of an ignition spark. The spark produced by an ignition voltage between two ignition electrodes and is present during the total spark duration.

Damage or bending of one or both attached to the pilot burner ignition during transport or installation may adversely affect the functioning of the ignition electrodes. Damage or bending can therefore make necessary replacement of the ignition electrodes.

Replacing the ignition electrodes can also be necessary when one of the electrodes is so distorted that it instead comes between the electrode tips between an electrode lead and another metal component to the current rollover and therefore the gas mixture can not be ignited.

Task Underlying

The invention has for its object to provide a burner having at least one ignition electrode is available, in which the above-mentioned problems do not occur or only to a reduced extent.

inventive solution

This object is solved by a burner comprising the features of claim 1. The burner can be configured in particular as a pilot burner.

According to the invention the solution of the problem is that the burner is equipped with at least one extending on its outer side ignition electrode, said electrode is associated with a protective element which projects beyond the outer side of the burner and the ignition electrode addition.

The advantage of the invention lies in the fact that the ignition electrodes are protected and therefore damage during transport or during installation and removal of the ignition electrodes can be avoided.

Advantageous developments of the invention

Advantageous developments are specified in the dependent claims.

In an advantageous development of the invention, the protective element to the outside of the burner is connected, so that the necessary stability is ensured.

Another advantageous further development is that the protective element surrounding the ignition electrodes, wherein the ignition electrode is at least partially covered lengthwise, so that an ignition electrode is at least well protected.

In addition, the protective element can be U-shaped and is secured with the open side and the outer side of the burner, so that the ignition electrode be protected on three sides to the outside. The protective element can completely enclose the electrodes at least in the front area near the electrode tips.

Alternatively, the protection element can be formed by at least one rib, so that a better accessibility of the ignition electrodes is ensured. The rib may extend parallel to the ignition electrode. It can also be located on both sides of the ignition electrode at least one rib.

Preferably the protection element consists of a flexurally rigid and impact-resistant material is produced, so that a deformation of the protective member, which could lead to a deformation of the internal ignition, is avoided.

A further advantageous development consists in the distance between the sensing element and the ignition electrode is at least as large that when concerns an ignition voltage at the ignition electrode no flashover between the protective element and the ignition electrode is done so that a current flashover between the ignition electrode and the protective element can be reliably avoided ,

Brief Description of Drawings

Further features, properties and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. It shows:<dl id="dl0001" compact="compact"><dt>1 shows</dt><dd>a burner with an ignition electrode,</dd><dt>FIG 2</dt><dd>a burner having ignition electrodes and a protection element comprising a U-shaped cross-section and surrounds the ignition electrodes in the front region, </dd><dt>FIG 3</dt><dd>a burner having igniter electrodes, and a protective element, which is formed of ribs and extends parallel to the ignition electrodes.</dd></dl>

Detailed description of the embodiment

The burner assembly illustrated in FIG 1 is part of a gas turbine plant, the preferred application of the invention. The burner assembly is however also suitable for gas-fired furnaces of boilers.

The burner assembly is comprised of at least one to a support plate (not shown in FIG. 1; s 2, 3) fixed to the first burner 2, which serves as a pilot burner and a second burner 1 serving as the main burner and in the middle of the first burner 2 is inserted coaxially. The first burner 2 has a burner head 4 with a swirl vane 3 and can be operated with natural gas E and / or heating oil H as fuel. The head 4 of the first burner 2 is arranged coaxially with respect to the burner axis, surrounded by an air supply channel 6 which serves (not shown) of the supply of the major part of the combustion air L to a groove formed downstream of the burner head 4 combustion zone. The annular gap, the pressurized combustion air L is supplied from a compressor of the gas turbine plant. The hot combustion gases flow into the turbine blading.

The serving as main burner second burner 1 is supplemented by the first, serving as pilot Boilers 2, ie for natural gas operation can be switched to the main burner operation with its lower NOx levels after starting and warming the Pilotbrenner-. The first burner 2 serves to stabilize the flame.

The second burner comprises nozzle pipes 5 and an air supply duct 6. The nozzle tubes are connected to a fuel supply system (not shown) and serve for the mixing of oil, gas or other gaseous or liquid fuel with the combustion air supplied to L. The air supply channel 6 leads the combustion air L optionally with admixed fuel the flame region to.

The ignition of the first burner 2 supplied air-fuel mixture is carried out via a bar-shaped or tubular electrode arrangement with two ignition electrodes 7. The ignition electrodes 7 extend substantially parallel to the axis of the first burner 2. In the region of the support plate 9, through which the ignition electrodes 7 are passed, however, the distance of the ignition electrodes 7 of the outer wall of the first burner is significantly greater. Also, the distance of the ignition electrodes 7 to each other is greater than in the region of the outer wall of the first burner 2. The ignition electrodes are fixed to connecting pieces 11 on the outer side of the first burner 2 in the region of the carrier plate.

2 shows as an exemplary embodiment for a burner according to the invention, a burner 2 is shown, are attached to the outer wall of two runs in the longitudinal direction of the burner ignition electrodes 2 7th The burner 2 can serve in particular as a first burner in the burner arrangement described with reference to FIG. 1

The ignition of the burner 2 are covered by a protection element 8, which is formed in the present example as a U-shaped bent sheet metal eighth The legs of the plate 8 each have a bent portion, in which they are secured to the outer wall of the burner second The mount 10 is advantageously effected by suitable releasable fasteners, such as screws, so that an access to the ignition electrodes 7 is possible in case of need. Instead of the releasable connection not releasable connections are possible, eg. Welded joints. The U-shaped metal sheet extending at least over the front part of the ignition electrodes 7, ie the portion which is close to the electrode tips 12th

The sheet 8 should be made of an impact resistant and rigid material such as steel. The distance of the sheet 8 from the ignition electrodes 7 should be at least so large that upon application of an ignition voltage occurs at the ignition electrodes 7 no flashover between the apron 8 and the ignition electrodes. 7 The specific value of the distance depends on the dielectric strength of the medium between the electrodes 7 and the apron 8 and the geometry of the ignition electrodes and the ruling on application of the starting voltage temperature. In the present embodiment, with air as the medium, a safety distance of at least 5 mm should be maintained if the ignition voltage is 5 kV.

Figure 3 shows a two mounted on its outer wall in the burner 2 ignition electrodes 7. Also this burner 2 can serve in particular as a first burner in the burner arrangement described with reference to FIG. 1

Right and left of the ignition electrodes 7 of the burner 2 shown in FIG 3 runs in each case a longitudinal rib 8. The longitudinal ribs 8 project from the surface of the burner 2 via the ignition electrodes 7 in front, so that the ignition electrodes 7 are protected from bumps. The ribs 8 are fixedly connected to the wall of the burner second The mounting 10 may for example be made by welding or soldering. Removable connections between the longitudinal ribs 8 and the burner 2, for example. By means of screws, although are also possible, but non-detachable connections are completely ausrechend, since the arrangement does not significantly restrict access to the ignition electrodes 7 and the ribs 8 thus for access to the electrodes 7 do not have to be removed.

As the sheet of the first embodiment should be 8 made of an impact resistant and rigid material such as steel ribs. The distance of the ribs from the ignition electrodes 7 should be at a starting voltage of 5 kV at least 5 mm, so that no current flashover can occur between an ignition electrode and a rib.

Finally, it should be noted that all the features which are mentioned in the application documents and in particular in the dependent claims, is to come in spite of made formal return covering on one or more specific claims, individually or in any combination of independent protection.