Combustion – Process of combustion or burner operation – Controlling or proportioning feed
Reexamination Certificate
1999-08-24
2001-04-03
Lazarus, Ira S. (Department: 3743)
Combustion
Process of combustion or burner operation
Controlling or proportioning feed
C431S022000, C431S042000, C431S281000
Reexamination Certificate
active
06210152
ABSTRACT:
FIELD OF TECHNOLOGY
The invention on hand relates to a burner for a heat exchanger according to the preamble of claim
1
. It also relates to a method for operating such a burner.
STATE OF THE ART
Usually, burners of gas turbines are operated in premix mode. Such premix burners are known from EP-B1-0 321 809 and DE-195 47 913.0. By using upstream fuel injection in such premix burners, the fuel is premixed with the air before the combustion takes place. This provides an explosive mixture for the further combustion inside the burner. In general, it can be noted that such new generation burners offer numerous advantages, for example, a stable flame position, lower pollutant emissions (CO, UHC, NOx), minimal pulsations, complete burnout, a larger operating range, good cross-ignition between the various burners, in particular when creating graduated loads, during which case the burners are operated independently from each other, an adaptation of the flame to the corresponding combustor geometry, a compact design, an improved mixing of the flow media, an improved “pattern factor” of temperature distribution in the combustor, i.e., a balanced temperature profile of the combustor flow.
If, however, unforeseen malfunctions occur during operation, this may result in flame instability. Once the flashed-back flame is able to stabilize inside the burner, it burns as a diffusion flame with a very high temperature, at about 1900° C. Within a short time, ranging from 10 to max. 30 seconds, the burner overheats and is destroyed. In any case, the gas turbine must be stopped, inspected, and repaired, resulting in tremendous costs. It was found that, in particular, in prototype gas turbines with new combustion technology or combustion of hydrogen-containing fuels (MBt or LBt gasses) a high risk exists in this regard.
DESCRIPTION OF THE INVENTION
The invention attempts to solve this problem. The invention, as characterized in the claims, is based on the objective of proposing measures for a burner and a process of the initially mentioned type that would maximize flame stability in the burner.
According to the invention it is proposed to provide the burners with a compact, contactless flame monitor in a suitable place.
The essential advantages of the invention are that the sensor installed in the burner reports a flashback of the flame. Then the premix fuel mixture is reduced, and the pilot fuel quantity is simultaneously increased, so that the total fuel quantity, and therefore the turbine output, remains constant. Because of the reduction, i.e., of the premix fuel quantity, the flashback flame can no longer stabilize in the burner; it is inevitably flushed out of the burner. This makes it possible to prevent a destruction of the burner.
Such a sensor or flame monitor can be realized with high-temperature-resistant glass fibers. These fibers are arranged so that their monitoring field covers the areas at risk, but not the pilot and premix flame burning normally. The UV portion (about 300-330 nm) of the radiation measured by the sensor undergoes a spectral analysis with suitable filters. A flashback in the burner can be detected within a matter of milliseconds via the ratio of the intensity at various wavelengths. If the combustor consists of a number of burners, it is possible to determine with suitable data acquisition in which burner the flame flashback has occurred, and suitable measures for eliminating the causes can be taken.
Advantageous and useful further developments of the solution according to the invention are characterized in the remaining claims.
The following is a more detailed discussion of the exemplary embodiments of the invention in reference to the drawings. Any characteristics not essential for the direct understanding of the invention have been ignored. Identical elements have been marked in the various figures with the same reference symbols. The flow direction of the media is indicated with arrows.
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Haffner Ken
Hobel Matthias
Ruck Thomas
ABB Research Ltd.
Burns Doane Swecker & Mathis L.L.P.
Clarke Sara
Lazarus Ira S.
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