Annular combustion chamber in a gas turbine engine and its operation method

Abstract

The invention relates to mechanical and power engineering, transport and other fields, particularly, to design of low-emission annular combustion chambers (CC) in jet gas turbine engines (GTE) and stationary gas turbine plants (GTP) based on low-emission burners with advance preparation and combustion of lean fuel and air mixtures and applying efficient operation method. The summary of this invention is as follows: - the annular CC GTE includes two coaxial rings of two-circuit low-emission burners with a porous element (PE). The burners are installed on the front wall of the flame tube. The burners ends lie in one plane. The burners inner channels are supplied only with pilot fuel. Diffusion combustion of the fuel is carried out in the standby flame. The outer channels are supplied with main fuel and compressed air from behind the compressor. Quality lean fuel and air mixture (FAM) is prepared in advance by means of jet supply of main fuel in air crossflow at the first stage and subsequent transfer of the resulting lean FAM through micro channels of the PE porous body at the second stage. Kinetic combustion of lean FAM is maintained using the standby flame; - the inner burner channels of the inner ring are gathered in the inner annular pilot fuel manifold, while the burners annular fuel receivers in the inner annular main fuel manifold; - flow swirl direction in the burners is alternated using axial vane swirlers to the opposite when shifting from one burner to the other adjacent burner within each ring to form periodic pair swirls covering two burners, one of which relates to the outer ring and the other to the inner ring of CC; - in start mode and in transient modes when the load is increased close to idle power, supply of main and pilot fuel to the inner ring burners is disconnected by closing the valves in the main and pilot fuel supply lines upstream of the inner main and pilot fuel manifolds, which allows to reduce two times the excess air factor in the outer ring burners; - relative pilot fuel consumption in all burners is reduced on the assumption that minimum nitrogen oxide emission is provided using fuel governors installed in main and pilot supply lines by maintaining the specified total consumption of main and pilot fuel and specified total excess air factor, while keeping combustion stability of lean fuel and air mixture. The above and some other proposed technical solutions allow to reduce full pressure losses, improve reliability of the annular CC GTE operation, widen the range of lean FAM stable combustion and provide better uniformity of temperature patterns in radial and circumferential directions, while reducing nitrogen and carbon oxide emissions, which supports the advantages of the proposed annular CC and its operation method compared to CC and its prototype operation method. Claims include two independent and five dependent clauses. The description includes five figures.

Description

technical field [0001] The present invention relates to a combustor (CC) mainly used in jet gas turbine engines (GTE) and stationary gas turbine plants (GTP), and to methods of its operation. Background technique [0002] In order to ensure a stable combustion of the fuel and air mixture (FAM), blunt body or vane swirlers are used (sometimes simultaneously) in this type of burner. In annular CC, unidirectional swirls in separate burners result in coaxial annular swirls. Typically there is a pressure loss due to wall friction in the flame tube while maintaining these swirls. This is why this toroidal swirl is considered derivative. In addition to the pressure loss, the flame intensity of the burner and the combustion stability of the FAM are reduced because a part of the derived swirl flow does not participate in the combustion. [0003] It should be noted that if all burners have the same swirl direction, the transfer of the flame from the burner actively ignited by FAM f...

AI Technical Summary

Problems solved by technology

[0027] - lower combustion chamber combustion intensity and fuel combustion efficiency, and loss of part of the FAM combustion stability due to the expansion of the volume of the front wall and the annular CC caused by the alternating displacement of every two burners outwards or towards the center of each ring sex

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