RU216775U1 - Modernized direct-flow swirl burner - Google Patents

Abstract

The utility model relates to fuel combustion plants and can be used to reduce emissions of nitrogen oxides. In a burner installed on a boiler or in a new burner, the existing gas-distributing tubes are supplemented with extension gas tubes that bring all the nozzles or part of them to the edge of the loophole and / or into the furnace along the perimeter of the loophole, a central channel of fuel gas is installed along the axis of the burner. As a result of the introduction of a modernized burner with extension gas tubes, jets of gaseous fuel flowing from nozzles into a space filled with flue gases eject flue gases and dilute the gaseous fuel with flue gases before mixing it with the air flow and igniting it. The reduction of NOx emissions occurs due to the organization of intra-furnace flue gas recirculation by means of flue gas ejection directly from the furnace with gaseous fuel jets, as a result of ejection, the concentration of reactants and the combustion temperature decrease. Mixers can be installed on the gas nozzles to organize a controlled ejection quality. The number, position, angle and type of nozzles of the burner extension tubes depends on the burner power, the aerodynamic characteristics of the burner air flow and the pressure of the gaseous fuel. The proposed upgraded burner provides a 40-70% reduction in nitrogen oxide emissions when burning gaseous fuel. The advantage of the proposed utility model lies in the possibility of reducing NOx emissions during the combustion of gaseous fuel without changing the elements of the furnace of the fuel combustion plant and reducing the technical and economic characteristics of the robot. 2 ill.

Description

The utility model relates to fuel combustion plants and can be used to reduce emissions of nitrogen oxides (NOx).

Direct-flow vortex burners are known, described in the article “Test results of burners with low-toxic emissions by Ecotop and Todd Combustion (USA) on boilers TG-104 and TGME-206 when burning associated and natural gas”, Kovalenko A.L. ., Kozlov V.G., Utkin A.P., Permyakov V.N., Thermal Power Engineering, 2003, No. 4, p. 41-44, which, while ensuring the quality of fuel combustion, do not provide low NOx emissions that meet modern requirements.

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 utility model is a method for reducing NOx emissions described in the following 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 2013-04-19, EP 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 19097 , EP 2479491A1 Published 2012-07-25, KR 2012-06-29, KR 2012-07-07-06, KR 2012-07-06, KR 2012-07-24, KR 20130061167A 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 diluted 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 general reduces the efficiency of NOx suppression. The considered inventions cannot be applied to the existing burners installed in the combustion plant.

Closer to the utility model is a group of inventions in which the principle of in-furnace recirculation is used due to the injection of fuel gas not into the air stream, but outside the burner mouth: 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 , 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. In these inventions, technical solutions are patented in which fuel gas and/or air are diluted with flue gases before they are mixed and reacted. The main condition for reliable combustion of fuel gas when using this technology is to maintain the temperature in the furnace of a fuel combustion plant 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 overall temperature of 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-burning plant.

The closest to the proposed utility model 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 on 2015-11-16, EP 1980788A1 published on 2008-10-15, US 6071115A published on 2000-06 -06, KR 1020170138042 published 2017-12-14, KR 101822997B1 published 2018-02-01, JP 6595089B2 published 2019-10-23, KR 102115576B1 published 2020-05-27, KR 10211430 published 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 part of the burner protruding into the furnace, and the impossibility of using them to reduce NOx emissions on existing burners installed in the combustion plant.

The prototype for the utility model is a straight-flow vortex burner (RU 2027101, FLOW-FLOW VORTEX BURNER, IPC F23C 11/00, F23D 14/00, published: 20.01.1995).

The main goal of the patented utility model is to reduce NOx emissions from fuel gas combustion due to low-cost modernization of burners without changing the elements of the combustion plant furnace. The solution to the problem is achieved by extending the gas-distributing tubes of the burner and leading the nozzles into the furnace along the perimeter of the loophole, and placing the central gas channel along the axis of the burner. Mixers can be installed on the gas nozzles to organize a controlled ejection quality. Due to the organization of intra-furnace recirculation of flue gases by ejecting flue gases directly from the furnace with fuel gas jets flowing from nozzles, gaseous fuel is diluted with flue gases before ignition, the concentration of reactants and the temperature of the torch decreases, which leads to a decrease in the formation of NOx.

In FIG. 1 shows a view from the furnace to the burner (the modernized burner is shown conditionally).

In FIG. 2 shows a longitudinal section of the burner with extension gas tubes that are inserted into the furnace and located along the perimeter of the loophole (for example, only two extension gas tubes are shown, according to one version, the extension gas tubes lead the nozzle into the furnace outside the air flow supplied from the burner, according to another variant extending gas tubes brings nozzles to the edge of the embrasure).

The burner consists of an air channel 1 in which an axial swirler 2 is located, gas-distributing tubes 3 located around the swirler 2 symmetrically to the longitudinal axis of the channel, a central fuel gas channel 4. Extension gas tubes 5 are attached to the gas-distributing tubes 3, which lead the nozzles 6 into the furnace outside the air flow 7 or extending gas tubes 8 that lead nozzles 6 to the edge of the embrasure. The diameter 9, on which the nozzles are installed, is determined by the aerodynamic characteristics of the air flow, the pressure of the gaseous fuel and the size of the embrasure.

As a result of the implementation of the utility model, the gaseous fuel jet 10 ejects flue gases 11, diluted with them, the new prepared fuel 12 reaches the air flow 7 from the burner and the combustion process occurs with lower concentrations of reactants and temperature, which reduces the formation of NOx. On the nozzle of gaseous fuel, a mixer 13 can be installed, which ensures the mixing of the ejected flue gases and gaseous fuel and the formation of a jet of diluted fuel. When the extension gas tubes 8 lead the nozzles 6 to the edge of the loophole into the furnace, the gas nozzles 6 are located in such a way that part of the gaseous fuel jet 10 is in the air, and part of the gaseous fuel jet is in the flue gases. The jets of gaseous fuel 10 flowing out of the nozzles 6 eject flue gases 11, are partially diluted with flue gases, and the combustion process occurs with lower concentrations of reactants and temperature, which reduces the formation of NOx.

The operation of the burner is carried out as follows.

The ignition of the burner takes place on the central channel of the fuel gas, no fuel gas is supplied to the peripheral channel. After the power of the combustion plant is increased above 20% and the furnace is heated to sufficient temperatures for stable ignition, fuel gas is supplied to the peripheral channel, then the burner power is increased by increasing the fuel gas flow through the peripheral channel with a constant or gradually decreasing fuel gas flow through the central channel . At maximum burner power, the fuel gas flow rate through the center channel may be 10% or less to ensure ignition stabilization. At intermediate loads, the ratio of fuel gas consumption between the peripheral and central channels depends on the design features of a particular furnace and is determined during the performance tests.

The use of the proposed device 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 the construction of an external flue gas recirculation system.

Claims (2)

1. A burner containing an air channel, an axial swirler, gas-distributing tubes located around the latter symmetrically to the longitudinal axis of the channel, forming a peripheral fuel gas channel, characterized in that the gas-distributing tubes of the peripheral fuel gas channel at the outlet are equipped with extension gas tubes with outlet nozzles that are wound into the furnace and are located along the perimeter of the loophole, and a central channel of fuel gas is installed along the axis of the burner. 2. The burner according to claim 1, characterized in that the nozzles are equipped with mixers for mixing gaseous fuel and ejected flue gases.

Images