DD216778A1 - COAL DUST SWIRL BURNER - Google Patents

Abstract

The invention relates to a pulverized coal swirl burner, in particular for the Zuend- and Stuetzfeuerbetrieb of large steam generators with an inner Primaerrohr for the supply of Brueden-dust mixture and surrounding the Primaerrohr secondary pipe for the combustion air, the at least one swirl grid for the Brueden dust Mixture. It is a stable ignition and combustion in the combustion of high-fiber fuels can be achieved if the mass flow of Brueden-dust mixture is equal to the combustion air or exceeds it. For this purpose, a swirl lattice is arranged at the outlet from the primer tube. By a cone-shaped Stroemungskoerper, which is fixed by the swirl lattice, the radial component of the tangential Abstroemung, which is generated in the swirl lattice, increased even further. The supply of combustion air can be twisted but also carried out unverdrallt, as is achieved by the tangential Abstroemung the dust Buerden mixture after burner good mixing with the combustion air flow.

Description

Title of the invention,

Coal dust swirl burner Field of application of the invention

The invention relates to a swirl burner for the combustion of dust-like fuels, in particular ballast-rich raw lignite, with a primary tube for the vapor-vapor mixture with a swirl grid and central displacement body.

Characteristic of the known technical solutions

For the combustion of dust-like fuels in steam generators jet burners are known, in which in each case via separate rectangular channels of the fuel and the air are supplied. Furthermore, diffusion burners are known where even in the burner itself, the supply of air via nozzles is tangential in the vapor-dust mixture stream. The burners work with external recirculation to bring the necessary ignition heat to the arnine mouth. In addition, they work with long flames and require long mixing and burnout paths. Therefore, swirling

bronner developed ', which in addition to the external recirculation to achieve an internal recirculation, which is achieved by pre-purging the combustion air and / or the vapor-vapor mixture (SU 805001). With large vapor-vapor streams, the ignition alone can not achieve the ignition-stabilizing recirculation. Therefore, the known swirl burner are not applicable for such large vapor-volume flows. It was therefore proposed a swirl burner for such fuel ratios, in which a closed core tube is arranged in the primary tube, which carries a swirl grid. By allowing the effectiveness of the internal obstruction, this type of torch is not applicable to smaller primary tube diameters, such as those needed for pilot burners for large scale steam generators.

Object of the invention

The aim of the invention is to achieve a stable ignition and combustion in the combustion of ballastreichen dust-like fuels in steam generators, primarily raw lignite coal from grinding drying plants.

Explanation of the essence of the invention

The invention is based on the application of a swirl burner with a primary tube for the mammalian nozzle and a secondary tube for the combustion air in which the vapor flow of the vapor-vapor mixture is equal to or exceeds that of the combustion air train and arrange that a stable ignition is achieved without additional support fuel. "

-Uüü.1983 * iü72Ö5

For this purpose, according to the invention, a swirl lattice is arranged at the exit from the primary tube in such a way that turbulence of the vapor / dust mixture takes place only after leaving the primary. "

pipe leads. By a fixed from the swirl grate known per se conical flow body, the radial component of the tangential outflow, which is generated in the swirl grille, additionally increased · The supply of combustion air can be twisted but also untwisted, since the tangential outflow of dust-vapor mixture after burner good mixing with the combustion air flow is achieved. ,

Although it is a round burner with annular dust introduction known in which a displacement cone is arranged in front of the central tube for the secondary air and this is distanced and supported by turning surfaces and turning strips, which are installed in the dust and air supply (DD 4!> 28). This solution is a round burner without any swirling effect. The envisaged on the dust side turning bars have, as described, the task of ensuring a uniform application to the burner outlet despite the one-sided dust supply. Furthermore, the open truncated cone, which is to allow a portion of the secondary air to enter the center of the flame body rectilinearly, in no way causes the typical internal backflow zone of a swirl burner. In contrast, the burner according to the invention has a strong swirl component due to the blade lattice arranged at the outlet. By the displacement body, the formation of a strong backflow of hot gases within the flame body is additionally supported in a known manner. Due to the arrangement according to the invention of the swirl lattice according to the outlet cross-section and at the same time use as a support element for the displacement body, a minimum

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painter in the dust flow and at the same time achieves favorable mixing conditions between fuel and air.

embodiment

The swirl burner consists essentially of the primary tube 1 for the male-dust mixture and a secondary tube 2 for the combustion air. At the exit from the primary tube, the swirl vanes 3 are arranged so that they fix a flow cone 4 outside of the primary tube. The vapors-dust stream receives in the swirl screen 3 a tangential acceleration, which leads to the generation of an outward directed outflow, which experiences no limitation by the primary tube, but can act freely. In addition there is an additional deflection of the flow to the outside * which is generated by the flow cone 4. Thus, a strong radial outflow is achieved, which leads to a large negative pressure area immediately behind the burner, with which a strong internal recirculation is generated, which returns the flue gases with combustion temperature level to the burner mouth and here ensures the warm-up and ignition of the registered dust mixture. ¹ Dor outside air curtain contributes to the heat insulation to the combustion chamber, whereby even with cold Umgobung a stable ignition is guaranteed. At the same time, the strong deflection of the dust mixture leads to intensive mixing with the combustion air flow blown in with less or without swirl, after or during this heating phase, by the combustion gases sucked back. The period between the exit of the dust particles from the primary pipe and their entry into the air curtain can preferably with the help of the degree of swirl of the air but also with the plump degree of the vapor-vapor mixture bzv /. the conical shape of the flow body varies, ie * the heating time of

the dust particles are optimized to ignition. The ignition of the dust is done once by a suitable Zündinitial the burner mouth. , The internal recirculation of the hot flue gases ensures the self-stabilization of the pulverized coal ignition for further operation.

-t'AttG, 1983 * 107205.

Claims (3)

Claim of invention. 1. pulverized coal swirl burner, in particular for Zündbzw. Support fire operation of GroSdampferzeugern, with an inner primary tube for the supply of the vapor-vapor mixture and a secondary tube surrounding the primary tube for the combustion air, which has at least one swirl lattice for dae vapor-mixture, characterized in that the Verdriggittar (3) for the vapor / dust mixture from the mouth of the primary tube (1) is mounted projecting and has a known centrally arranged flow body (4), while the secondary tube (2) is formed so that the combustion air is injected with less or no twist . 2. Burner according to item 1, characterized in that the flow body (4) has the shape of a concave paraboloid. 3. Burner according to item 1, characterized in that the cross section of the primary (1) and secondary pipe (2) is polygonal, preferably rectangular. For this 1 sheet drawings.