RU2797080C1 - Method for reducing nitrogen oxide emissions and a dual-flow burner for its implementation - Google Patents

Abstract

FIELD: energy.

SUBSTANCE: method for reducing emissions of nitrogen oxides consists in the fact that in a burner containing a cylindrical body in which central and peripheral air channels with swirlers are located, the main and additional gaseous fuel collectors, gas-distributing tubes installed on a circle between the air channels and connected to different collectors, the gas-distributing tubes of one of the gaseous fuel collectors at the outlet are provided with extension gas tubes, which are placed along the surface of the loophole, the outlet nozzles of the extension gas tubes are led into the furnace beyond the air flow exiting the burner and are placed along the perimeter of the loophole, with jets of gaseous fuel flowing from the nozzles, flue gases are ejected, the gaseous fuel is diluted with flue gases before ignition.

EFFECT: invention allows to reduce emissions of NO_x.

3 cl, 3 dwg

Description

The invention relates to fuel combustion plants and can be used to reduce emissions of nitrogen oxides (NOx) during the combustion of gaseous fuels.

A device for burning gaseous fuels is known (RU 2076271 C1, IPC F23D 14/24, published on 03/27/1997) burner described in the article "Results of integrated tests of the boiler E-160-3.9-440GM HPP-1 of Mosenergo JSC with a horizontal layout gas ducts”, Galetsky N.S., Ph.D. tech. Sci., Enyakin Yu.P., Schwartz A.L., Doctor of Engineering. Sci., Shtalman S.G., Gombolevsky V.I., Thermal power engineering No. 9 2004, pp. 8-13, including central and peripheral air channels with swirlers located in a cylindrical body, main and additional gaseous fuel collectors installed on a circle between air channels gas-distributing tubes connected to different collectors.

A device for burning fuel is known (RU 2480673 C1, IPC F23D 14/24, published on 04/27/2013, RU 61010 U1, IPC F23С 1/08, F23D 17/00, published on 02/10/2007), the burner described in the article "Modernization of TGMP boilers -314C, equipped with cyclone pre-furnaces to reduce harmful emissions and improve the reliability of burner devices and heating surfaces "Zroychikov N.A., Enyakin Yu.P., Glusker B.N., Galas I.V., Tsypkin Yu.M. ., Chuprov V.V., Vereshchetin V.A., Thermal power engineering No. 12 2002, pp. 17-21, including central and peripheral air channels with swirlers located in a cylindrical body, main and additional gaseous fuel collectors, a central one is installed along the burner axis gaseous fuel supply channel, gas-distributing tubes of the peripheral gaseous fuel channel are located on the circumference between the air channels.

The disadvantage of the considered burners is the low environmental efficiency of fuel combustion, due to the design flaws of the burner in the method of organizing the combustion process, in which all gaseous fuel is supplied to the air.

One of the effective ways to reduce NOx emissions is the use of forced flue gas recirculation, which reduces the flame temperature and reduces the concentration of reactants that determine the formation of NOx. In this case, the most effective method is the supply of flue gases to the burner channels (SU 1 101 622 A1, IPC F23D 17/00, published on 07/07/1984). This method is implemented in the burner of the TGMP-204 boiler, which consists of two air supply channels (central and peripheral), equipped with tangential registers, a recirculation flue gas inlet channel is located along the periphery, and an oil burner is installed in the center of the heater. The gas part of the burner consists of an annular gas collector, a gas-distributing nozzle in the form of a cone with holes and a gas supply pipe. The inner pipe of the gas collector is the guide pipe of the steam-mechanical nozzle (Y.P. Storozhuk. Testing the TGMP-204 boiler of the 800 MW unit after the reconstruction of the recirculation flue gas inlet into the furnace / Y.P. Storozhuk, D.R. Nosulko // Thermal power engineering. - 1984. - No. 5 - S. 13-15.). This burner failed to achieve a good result in reducing NOx emissions due to design flaws in the way the combustion process is organized.

Successful NOx suppression requires that recirculation flue gases do not ballast in the root area of the burner, but reach the combustion core, where the main formation of NOx occurs. The main disadvantage of this method of organizing combustion remains the need for a system of forced recirculation of flue gases with a recirculation smoke exhauster.

Close to the invention is a method for reducing NOx emissions, described in the inventions: RU 2689654C2 published on 2019-05-28, SU 1588987A1 published on 1990-08-03, SU 1695040A1 published on 1991-11-30, KR 101254928B1 published on 2013-04- 19EP 0893651A1 published 1999-01-27, US 2012/0186265A1 published 2012-07-26, WO 01|07833A1 published 2001-02-01, US 2005/0239005A1 published 2005-10-27, US 4380429 published 1998-12-07, EP 2479491A1 published 2012-07-25, KR 20120070201A published 2012-06-29, KR 20120074868A published 2012-07-06, KR 20120082647A published 2012-07-24, KR 201300 61167A published 2013-06-10, US 5350293 published 1994- 09-27. In some cases, these inventions were developed in order to stabilize the combustion regime by sucking incandescent combustion products from the furnace. In these inventions, flue gas recirculation is organized by the burners themselves without additional flue gas supply systems, including a chimney system and a recirculation smoke exhauster. The flue gases are ejected into the combustion zone, which burns the dilute gaseous fuel and reduces the formation of NOx. The disadvantage of the method used in these inventions is: the complexity and high cost of the design of the burners, a small amount of sucked flue gases from the furnace. The flue gases are ejected by the fuel or air flow at the burner mouth inside the main air flow, combustion takes place in the air environment, which in total reduces the NOx suppression efficiency. The considered inventions cannot be applied to the existing burners installed in the combustion plant.

Closer to the invention is a group of inventions that use the principle of intrafurnace recirculation due to the injection of gaseous fuel not into the air stream, but outside the burner mouth: US 5542840A published 1996-08-06, US 6773256B2 published 2004-08-10, RU 2426030C2 published 2011 -08-10, US 5275552A published 1994-01-04, US 20080096146A1 published 2008-04-24, US 6007325A published 1999-12-28, US 7670135B1 published 2010-03-02, US 9593847B1 published 2017-03-14, US 9593848A1 published 2015-12-10, US 20150285491A1 published 2015-10-08, US 6875008 B1 published 2005-04-05, KR 101213883B1 published 2012-12-18, WO2014162074A1 published about 2014-10-09, US6773256 published 2004-08 -10, WO2008104158A3 2008-09-04. In these inventions, technical solutions are patented in which gaseous fuel and/or air are diluted with flue gases before they are mixed and reacted. The main condition for reliable combustion of gaseous fuels using this technology is to maintain the temperature in the combustion plant furnace above the ignition temperature of the fuel and use a stable flame stabilizer, while ignition and combustion stabilization is provided by special loopholes or the general temperature in the furnace. The disadvantages of these inventions are the complexity of the design, the need to use a special loophole made of heat-resistant concrete and the impossibility of their use for existing burners installed in a fuel combustion plant.

Closest to the proposed invention is a group of inventions in which the entire burner head (gas-distributing device with an air channel) protrudes into the furnace: KR 101569455B1 published 2015-11-16, EP 1980788A1 published 2008-10-15, US 6071115A published 2000-06- 06, KR 1020170138042 published on 2017-12-14, KR 101822997B1 published on 2018-02-01, JP 6595089B2 published on 2019-10-23, KR 102115576B1 published on 2020-05-27, KR 102 143032B1 published on 2020-08-11. In this group of inventions, flue gas ejection is organized by gas nozzles with cylindrical nozzles located in the furnace along the outer perimeter of the burner air channel. The disadvantages of these inventions are the complexity of the design, the need to use special heat-resistant alloys of the burner part protruding into the furnace, and the impossibility of using them to reduce NOx emissions on existing burners installed in the fuel combustion plant.

The prototype for the invention is a device for burning gaseous fuels (RU 2 076 271 C1, IPC F23D 14/24, published 03/27/1997)

The main goal of the patented invention is to reduce NOx emissions during the combustion of gaseous fuels due to low-cost modernization of the burners without changing the elements of the combustion plant furnace. The invention can be applied to the modernization of installed, existing burners in a fuel combustion plant, as well as new burners. The solution of the problem is achieved by the fact that the gas-distributing tubes of the burner of one of the gaseous fuel collectors lengthen and lead the nozzles to the edge of the loophole into the furnace in the zone between the air flow of the burner and the flue gases, so that part of the jet of gaseous fuel is in the air, part of the jet is in the flue gases. A retrofit option is possible, in which the gas tubes lead the nozzles into the furnace outside the air flow and are located along the perimeter of the loophole in the furnace, so that the jets of gaseous fuel are completely in the flue gases. Mixers can be installed on the gas nozzles to organize a controlled ejection quality. Flue gases are ejected by jets of gaseous fuel flowing from the nozzles, the gaseous fuel is diluted with flue gases before ignition. As a result of the organization of intra-furnace flue gas recirculation, by ejecting flue gases directly from the furnace with gaseous fuel jets, NOx is effectively suppressed by reducing the flame temperature and the concentration of reactants.

In FIG. 1 shows a longitudinal section of a double-flow burner with elongated gas tubes (only two elongated tubes are shown), which lead nozzles along the surface of the loophole into the furnace outside the air flow and are located along the perimeter of the loophole in the furnace. Figure 2 shows a longitudinal section of a double-flow burner with elongated gas tubes that lead nozzles to the edge of the loophole into the furnace. Figure 3 shows a view from the furnace to a dual-flow burner (upgradable burner is shown conditionally).

A double-flow burner consists of an air box 1, a cylindrical body consisting of an outer air shell 2 and an inner air shell 3, which form the central 4 and peripheral 5 air channels with swirlers 6 and 7, the central pipe 8 for installing the nozzle 9, the main 10 and the additional 11 gaseous fuel collector, gas-distributing tubes 12 are installed around the circumference between the air channels, connected to different collectors. In the figure 1, to the gas-distributing tubes 12 of one of the collectors, extension gas tubes 13 are attached, which lead the nozzles 14 into the furnace beyond the air flow 15 and are located along the perimeter of the loophole in the furnace, so that the jet of gaseous fuel 16 is completely in the flue gases 17. In figure 2, gas-distributing tubes 12 are connected with extension gas tubes 18, which lead nozzles 14 to the edge of the loophole into the furnace in the zone between the air flow of the burner 15 and flue gases 17, so that part of the jet of gaseous fuel is in the air, part of the jet is in the flue gases.

In FIG. 3 shows a view from the furnace to a two-flow burner (the modernized burner is shown conditionally), in which the extension gas tubes 13 lead the nozzles 14 into the furnace outside the air flow. The diameter 20 on which the nozzles are mounted is determined by the aerodynamic characteristics of the air flow, the pressure of the gaseous fuel, and the size of the loophole.

As a result of the introduction of such a device, in the case when the extension gas tubes 13 lead the nozzles 14 into the furnace outside the air flow 15, so that the nozzles 14 are completely in the flue gases, the jets of gaseous fuel 16 flowing from the nozzles 14 eject the flue gases 17, diluted with them, the new prepared fuel 18 reaches the air stream 15 and the combustion process occurs at lower temperatures and concentrations of reactants, which reduces the formation of NOx. On the nozzle of gaseous fuel, a mixer 19 can be installed, which ensures the mixing of the ejected flue gases and gaseous fuel and the formation of a jet of diluted fuel. In the case when the extension gas tubes 18 lead the nozzles 14 to the edge of the embrasure into the furnace, the gas nozzles 14 are located in such a way that part of the gaseous fuel jet 16 is in the air, and part of the gaseous fuel jet is in the flue gases. The jets of gaseous fuel 16 flowing out of nozzles 14 eject flue gases 17, are partially diluted with flue gases, and the combustion process occurs at lower temperatures and concentrations of reactants, which reduces the formation of NOx.

The burner is ignited on the gaseous fuel channel, to which extension gas pipes are not connected (central), into the channel to which extension gas pipes are connected (peripheral), gaseous fuel is supplied after gaining 20% of the power of the combustion plant and heating the furnace to sufficient temperatures sufficient for stable ignition .

The use of the proposed method for reducing NOx emissions provides a reduction in the content of NOx in flue gases by 40-70% without reducing the technical and economic characteristics of the combustion plant and building an external flue gas recirculation system.

Claims (3)

1. A method for reducing emissions of nitrogen oxides, which consists in the fact that in a burner containing a cylindrical body in which central and peripheral air channels with swirlers are located, the main and additional gaseous fuel collectors, gas-distributing tubes installed on a circle between the air channels and connected to to different manifolds, the gas-distributing tubes of one of the gaseous fuel manifolds at the outlet are provided with extension gas tubes, which are placed along the surface of the loophole, the outlet nozzles of the extension gas tubes are led into the furnace beyond the air flow exiting the burner, and are placed along the perimeter of the loophole, with jets of gaseous fuel, flowing from the nozzles, flue gases are ejected, the gaseous fuel is diluted with flue gases before ignition. 2. A double-flow burner, comprising a cylindrical body, central and peripheral air channels with swirlers, main and additional gaseous fuel manifolds, gas-distributing tubes installed on a circle between the air channels and connected to different manifolds, gas-distributing tubes of one of the gaseous fuel manifolds at the outlet are equipped with extension gas pipes, which are placed on the surface of the loophole, the outlet nozzles of the extension gas tubes are brought into the furnace beyond the air flow exiting the burner, and are placed along the perimeter of the loophole. 3. Double-flow burner according to claim 2, characterized in that mixers are installed on the gas nozzles.

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