RU215171U1 - Device for upgrading the burner in order to reduce emissions of nitrogen oxides - Google Patents

Abstract

The utility model relates to fuel combustion plants and can be used to upgrade burners in order to reduce nitrogen oxide emissions. The device consists of an additional gas collector, gas-distributing tubes, which form a peripheral channel of fuel gas. The gas-distributing tubes are placed in the air channel between the outer and inner shells of the burner air channel and lead the nozzles into the furnace along the loophole perimeter outside the air flow. Gas-distributing tubes are placed on the surface of the burner mouth, embrasure and screen pipes, which makes it possible to modernize the burner without changing the design of the combustion plant itself. The jets of fuel gas flowing from the nozzles into the space filled with flue gases eject the flue gases and dilute the fuel gas with the flue gases before mixing it with the air stream and igniting it. The reduction of NOx emissions occurs due to the organization of intra-furnace flue gas recirculation as a result of flue gas ejection directly from the furnace with fuel gas jets, reducing the temperature and concentration of reactants. Mixers can be installed on the gas nozzles to organize a controlled ejection quality. The number, location, angle and type of peripheral fuel gas supply device depends on burner power, burner airflow aerodynamics and fuel gas pressure. The proposed device provides a reduction in emissions of nitrogen oxides by 40-70% when burning fuel gas. The advantage of the proposed method for reducing NOx emissions during the combustion of fuel gas is the possibility of its application for the modernization of burners installed on the fuel combustion plant without changing the elements of the furnace of the fuel combustion plant. 1 w.p. f-ly, 2 ill.

Description

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

Single-flow fuel gas burners are known, such as GMU, which, while ensuring the quality of fuel combustion, do not provide low NOx emissions. The unified oil-gas burner of the GMU type (OST 108.836.05-82 “Oil-gas burners and loopholes of stationary steam boilers”), which is common in Russia, consists of a nozzle assembly, a gas part and an air guide. The nozzle assembly includes a steam-mechanical nozzle with a flap. 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 injector. The air guide device of the GMU type burner consists of an air box and two bladed swirlers: axial and tangential. Inside the box there is a partition that divides the air flow into two streams.

The disadvantage of the GMU type burner 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 fuel gas 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 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 2012-20074868A Published 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 total reduces the NOx suppression efficiency. 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 unified oil-gas burner of the GMU type (OST 108.836.05-82 “Oil-gas burners and loopholes of stationary steam boilers”), which, while ensuring the quality of fuel combustion, does not provide low NOx emissions.

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 utility model can be used to upgrade installed, operating burners in a combustion plant. The solution of the problem is achieved by the fact that an additional peripheral channel of fuel gas is built into the burner, which removes the fuel gas to the area outside the air flow along the perimeter of the loophole, while the gas-distributing tubes are installed without changing the elements of the furnace of the fuel-burning installation. Mixers can be installed on the gas nozzles to organize a controlled ejection quality. Due to the organization of intra-furnace flue gas recirculation, by ejecting flue gases directly from the furnace with fuel gas jets flowing from nozzles located in the furnace outside the air flow, NOx is effectively suppressed as a result of a decrease in the flame temperature and the concentration of reactants.

In FIG. 1 shows the proposed device. In FIG. 2 shows a longitudinal section of a GMU-type burner with a patented device.

The proposed device consists of a gas collector 1, gas-distributing tubes 2, leading nozzles 3 into the furnace along the perimeter of the burner embrasure. A mixer 4 can be installed on the nozzles of the peripheral channel of the fuel gas, which ensures the mixing of the ejected flue gases and fuel gas and the formation of a diluted fuel jet. Diameter 5, on which the nozzles of the additional peripheral channel of the fuel gas are installed, is determined by the aerodynamic characteristics of the air flow and the pressure of the fuel gas.

Modernization of the burner device takes place as follows: into a burner installed on a fuel combustion plant, or into a new burner, consisting of an air box 6, an external air shell 7 and an inner air shell 8, a central fuel gas supply pipe 9 with a cone nozzle 10 with holes inside The barrel for the oil burner with the oil burner 11 is placed in the central pipe of the fuel gas, and the peripheral fuel gas channel is built into the annular gap of the air channel between the outer air shell and the inner air shell. Around the loophole there may be screen pipes of the combustion plant 12.

As a result of the introduction of such a device, the fuel gas 13 flowing from the nozzles 3 ejects the flue gases 14, diluted by them, the new prepared fuel 15 reaches the air flow 16 and the combustion process occurs with lower temperatures and concentrations of reactants, which reduces the formation of NOx.

The central channel of the fuel gas of the modernized burner ensures the stability of fuel combustion.

The operation of the burner device with the proposed device for reducing NOx emissions is carried out as follows: the burner is ignited on the central channel of the fuel gas of the modernized burner, 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 reduces 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 a peripheral channel of fuel gas, consisting of a gas manifold, gas-distributing tubes with nozzles coming out of the gas manifold, outer and inner shells, forming an annular air channel between themselves, in which gas-distributing tubes are placed, characterized in that the gas-distributing tubes are located on the surface of the screen pipes, and the nozzles of the gas-distributing pipes are placed in the furnace along the perimeter of the loophole outside the air flow exiting the burner. 2. The burner according to claim. 1, characterized in that the nozzles are equipped with mixers.

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