WO1992001194A1 - Procede de reduction des emissions d'oxyde d'azote dans la combustion de differents types de combustibles - Google Patents

Procede de reduction des emissions d'oxyde d'azote dans la combustion de differents types de combustibles Download PDF

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Publication number
WO1992001194A1
WO1992001194A1 PCT/FI1991/000215 FI9100215W WO9201194A1 WO 1992001194 A1 WO1992001194 A1 WO 1992001194A1 FI 9100215 W FI9100215 W FI 9100215W WO 9201194 A1 WO9201194 A1 WO 9201194A1
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WO
WIPO (PCT)
Prior art keywords
fuel
combustion
air
fed
plasma torch
Prior art date
Application number
PCT/FI1991/000215
Other languages
English (en)
Inventor
Pentti Salmelin
Martti Äijälä
Original Assignee
Imatran Voima Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Imatran Voima Oy filed Critical Imatran Voima Oy
Publication of WO1992001194A1 publication Critical patent/WO1992001194A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C6/00—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion
    • F23C6/04—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection
    • F23C6/045—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection with staged combustion in a single enclosure

Definitions

  • the present invention relates to a method in accordance with the preamble of claim 1 for reducing the emissions of harmful oxides of nitrogen formed in the combustion of various kinds of fuels.
  • Lowered content of nitrogen oxides (NO x ) in flue gases released into the environment are currently attempted to be achieved by pyrotechnical methods, different additive injections and catalytic methods.
  • the various pyrotechnical methods to reduce NO x emissions include recirculation of flue gases, water or steam injection, two-stage firing, use of low-NO x burners and staged fuel feed. These methods reduce emission rates by approx. 5...50 %. For instance, an initial level of 450 mg/MJ can be reduced to a level of 200...400 mg/MJ. The costs of these methods cost are 20...35 % of those of the catalytic category. Ammonia or urea -is most generally used as the additive for lowering emissions of oxides of nitrogen.
  • Results obtained by additives can be more effective than those achievable by pyrotechnical methods; and moreover, additives can be used to complement pyrotechnical methods. Injection methods are expensive to implement, and they may cause corrosion problems in the furnace; further, nitrous oxide may be formed, at least when urea is used.
  • Catalytic methods offer a reduction of NO x compounds up to 80 %, thereby making it possible to achieve a level even less than 100 mg/MJ. When aiming at such a low emission level, this technique is at its best in conjunction with a firing technology developed for low NO x emissions. Investments and operating costs of catalytic methods are high.
  • Pyrotechnical methods offer only a limited success which means that mere resorting to pyrolytic techniques in new installations is not sufficient for meeting set maximum allowable emission limits.
  • the catalytic methods are very expensive, so their use increases the production costs of energy.
  • the different injection methods available are partly relatively inefficient, cause corrosion and, with increased injection rates, can cause odour problems in the vicinity of the power plant.
  • the invention is based on burning the fuel in an extremely abruptly staged manner and forced ignition of the fuel under extremely air-deficient conditions with the help of a plasma torch.
  • the invention provides outstanding benefits.
  • the abruptly staged combustion concept made possible by the use of plasma torch ignition offers a way of utilizing pyrotechnical methods in a manner which attains NO x emission levels as low as those achievable by means of conventional catalytic methods. This further makes it possible to get below the present maximum emission rate limits using low-cost pyrotechnical methods, thus offering large cost savings over catalytic methods in new installations.
  • plasma torch ignition it is possible to use forced ignition of the fuel in extremely air-deficient combustion conditions, combined with abruptly staged combustion, whereby an appreciably improved reduction of N0 X emissions is achieved over conventional staged combustion techniques.
  • the method according to the present invention is capable of achieving NO x emission reductions by up to 80 %.
  • the use of a plasma torch realizes a good combustion process in extremely difficult pyrotechnical conditions and creates a favourable atmosphere for perfect combustion of the fuel.
  • the available combustion chamber volume is maximally utilized, because the ignition point of the fuel is brought close to the burner, the ignition point is controllable and a sufficiently long retention time in the combustion process can be ensured.
  • Figure 1 shows diagrammatically a burner suitable for the implementation of the present invention.
  • Figure 2 shows the test arrangement for investigations performed in the use of the method according to the invention.
  • Fig. 1 shows diagrammatically a burner, operated by a plasma torch and suitable for the implementation of the present invention.
  • the fuel fed to the burner is pulverized coal.
  • the burner includes the plasma torch 1, a fuel feed union 2, a first auxiliary air feed union 3 and a second auxiliary air feed union 4.
  • the fuel feed union 2 and the air feed unions 3 and 4 are joined to the burner perpendicularly to its longitudinal axis, whereby the fuel and combustion air fed to the burner are forced to a rotational motion about the longitudinal axis of the burner.
  • the burner shown here is a staged burner, in which fuel combustion at the different stages 8, 9, 10 is adjusted by altering air feed volumes to the stages.
  • the fuel fired in the burner is routed to a first gasification zone 8 in front of the plasma torch 1.
  • Air volume along with fuel feed at this stage is extremely small so that the air volume used is 5...30 % of the overall combustion air volume necessary for complete combustion.
  • the stoichiometric coefficient at this gasification stage is approx. 0.05...0.3. Because of the extremely low air content of the fuel entering the stage 8, complete combustion of fuel at this stage 8 is avoided.
  • the hot flame, which has a high energy density, of the plasma torch 1 performs an efficient gasification of the fuel, whereby carbon monoxide and hydrogen are formed simultaneously as the hot flame of the plasma torch 1 performs the forced ignition of a portion of the fuel and formed carbon monoxide. Resultingly, the burning carbon monoxide further performs an efficient gasification of the fed coal.
  • the temperature at the zone 8 is locally 3500 °C, advantageously even above 4000 °C.
  • the partially burning and gasified fuel flows forward in the burner to the next zone 9, wherein it meets next with the auxiliary air fed via a first auxiliary air feed union 3.
  • the air volume at this stage, together with the air volume from the previous stage 8, is 5...50 % of the overall air volume.
  • a major portion of the fuel is gasified into carbon monoxide, and water contained in the fuel is dissociated into hydrogen and oxygen under the plasma torch flame heat from the previous stage and the heat emitted from the subsequent stages 8, 9.
  • the fuel mixture containing carbon monoxide and hydrogen in abundance is ignited and completely combusted in the next zone 10 by virtue of additional air fed into the mixture via a second auxiliary air feed union 4, whereby the gasified fuel ignites when the stoichiometric air/fuel ratio increases to a sufficiently high value.
  • additional air can be fed via a second auxiliary air feed union 3 in order to further gasify the fuel in the zone 10, whereby ignition is performed with the help of combustion air fed into the actual combustion chamber, e.g., a power plant furnace.
  • the overall volume of primary and secondary air fed by the first 3 and second 4 auxiliary air unions is relatively small, each air volume into the fuel mixture being maximally approx. 10 % of the required overall air volume, but preferably only approx. 1...5 % of the overall air volume.
  • the rest of the necessary combustion air volume is fed into the combustion chamber used, e.g., a furnace.
  • staged combustion technique described above offers significant reductions of NO x emissions in combustion processes.
  • the greatest difference between the staged techniques according to the invention and conventional staged combustion techniques is therein that the combustion method according to the present invention allows suffi ⁇ ciently abruptly staged combustion.
  • an efficient method In order to attain an efficient chemical reduction of nitrogen oxides, an efficient method must be available for the gasification of the fuel as a sufficiently air-deficient mixture. This is necessary to make all oxygen contained in the mixture to react with the fuel, instead of nitrogen.
  • a sufficiently air-deficient mixture can be efficiently gasified only with the help of the flame having a high energy density delivered by a plasma torch.
  • the decreased quantity of oxides of nitrogen is achieved on maintaining the conditions in the hot zones of the flame, particularly the plasma torch flame, strongly reducing with the help of staged combustion. Then, oxides of nitrogen formed in the hot flame are reduced to molecular nitrogen. Similarly, with the help of staged combustion, temperatures in the other zones of the flame are maintained so low as to avoid formation of oxides of nitrogen. Because the plasma flame does not need fuel or combustion air, it is void of oxygen necessary for the formation of oxides, thus permitting a rapid reduction of oxides of nitrogen possibly formed in the extremely air-deficient conditions.
  • the plasma gas can also be nitrogen without causing an essential increase of NO x content, because oxides of nitrogen formed by reacting with the combustion air are rapidly reduced in the first air-deficient stages of the combustion process. Instead of nitrogen, the plasma gas can also be any other inert gas.
  • the combustion process in accordance the present invention was investigated measuring concentrations of oxides of nitrogen achievable in tests performed according to the invention.
  • a burner shown in Fig. 1 was connected to a test boiler 6' in the manner illustrated in Fig. 2.
  • the fuel and air connection unions of the burner shown in Fig. 2 are designated with the same reference numbers as those shown in Fig. l.
  • the boiler 6 is further equipped with a third air feed union 5 and a flue gas scrubber 7.
  • the purpose of the test runs was to study the effect of different parameters on NO x emission levels.
  • test runs were performed in order to investigate the effect of the following factors on the NO x emission levels in flue gases from the burner.
  • Test run part 11a was performed using a smaller tertiary air flow rate than in test run part lib.
  • Test run part 8a was performed using air as the plasma torch gas, while nitrogen was
  • test run part 8b 2) used as plasma gas in test run part 8b.
  • test run part lla the tertiary air flow rate was smaller than in test run part lib.
  • the above tables clearly show that abrupt staging achieves a substantial reduction in NO x emissions. Lowest emission levels are attained by feeding less than 30 % of the combustion air volume into the burner as the transport gas of fuel transfer, while the primary and secondary air volumes together form less than approx. 10 % of the overall combustion air volume.
  • the combustion method according to the present invention can be applied to firing with other kinds of gaseous, liquid or solid fuels.
  • the method can be adapted to all types of fired power plants such as boilers, combustion chambers of gas turbines and different kinds of furnaces. Fuel and air can be fed into the burner along its longitudinal axis, as well. It is also possible to have a greater number of air and fuel feed unions than those discussed in the text above.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)

Abstract

L'invention décrit un procédé de réduction des émissions d'oxyde d'azote dans des processus de combustion de produits combustibles solides, liquides ou gazeux. L'invention se base sur une combustion du combustible extrêment échelonnée. Le combustible est d'abord introduit dans une atmosphère où l'air est raréfié afin d'obtenir les conditions nécessaires à la réduction des émissions d'oxyde d'azote, dans la flamme d'une torche de plasma (1) où le combustible est gazéifié et soumis à une inflammation forcée. On introduit de l'air supplémentaire en au moins une étape, dans le flux de combustible partiellement gazéifié dans le but de poursuivre la gazéification dudit combustible, après quoi il est véhiculé vers la chambre de combustion proprement dite, par exemple, un fourneau, un brûleur ou chambre de même type (6) dans laquelle se termine sa combustion. La flamme est mise dans des conditions de réduction des émissions d'oxyde d'azote à cause de l'échelonnement abrupt et, de ce fait, les oxydes d'azote qui se forment dans la flamme sont réduits avant de pouvoir sortir avec les gaz de combustion.
PCT/FI1991/000215 1990-07-13 1991-07-08 Procede de reduction des emissions d'oxyde d'azote dans la combustion de differents types de combustibles WO1992001194A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI903548 1990-07-13
FI903548A FI87949C (fi) 1990-07-13 1990-07-13 Foerfarande foer reducering av kvaeveoxider vid foerbraenning av olika braenslen

Publications (1)

Publication Number Publication Date
WO1992001194A1 true WO1992001194A1 (fr) 1992-01-23

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Application Number Title Priority Date Filing Date
PCT/FI1991/000215 WO1992001194A1 (fr) 1990-07-13 1991-07-08 Procede de reduction des emissions d'oxyde d'azote dans la combustion de differents types de combustibles

Country Status (5)

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CN (1) CN1059021A (fr)
AU (1) AU8093091A (fr)
FI (1) FI87949C (fr)
PL (1) PL291046A1 (fr)
WO (1) WO1992001194A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999019668A1 (fr) * 1997-10-10 1999-04-22 Kvaerner Pulping Oy Procede et agencement pour optimiser l'oxydation pendant la combustion de carburants gazeux et liquides
WO2002068872A1 (fr) 2001-02-27 2002-09-06 Yantai Longyuan Power Technology Co., Ltd. Ensemble cathode et allumeur a plasma pourvu d'un tel ensemble cathode
CN101749700A (zh) * 2010-03-04 2010-06-23 郑平安 一种煤粉炉微油点火燃烧方法
DE102015104401A1 (de) 2015-03-24 2015-05-07 Mitsubishi Hitachi Power Systems Europe Gmbh Verfahren zur Verminderung von NOx-Emissionen bei der Verbrennung von staubförmigem Brennstoff
DE102015104406A1 (de) 2015-03-24 2015-05-21 Mitsubishi Hitachi Power Systems Europe Gmbh Verfahren zur Verminderung von NOx-Emissionen bei der Verbrennung von staubförmigem Brennstoff

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1076086C (zh) * 1997-10-06 2001-12-12 杨锦耀 用等离子体激励汽车发动机燃烧室内燃料燃烧的方法
CN100504164C (zh) * 2006-06-30 2009-06-24 中国科学院工程热物理研究所 一种低氮氧化物排放的燃煤方法
WO2009009948A1 (fr) * 2007-07-19 2009-01-22 Yantai Longyuan Power Technology Co., Ltd. Brûleur allumé par plasma
CN114959171A (zh) * 2015-01-27 2022-08-30 杰富意钢铁株式会社 电炉以及利用电炉制造铁水的方法
CN104633658B (zh) * 2015-02-15 2016-11-02 重庆赛迪热工环保工程技术有限公司 一种低氧化氮烧嘴
CN105737152B (zh) * 2016-03-10 2017-09-29 陈维汉 一种分级预混旋流低氮燃烧的燃烧装置

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4240784A (en) * 1978-09-25 1980-12-23 Dauvergne Hector A Three-stage liquid fuel burner
US4381718A (en) * 1980-11-17 1983-05-03 Carver George P Low emissions process and burner
US4509434A (en) * 1981-02-27 1985-04-09 Villamosipari Kutato Intezel Procedure and equipment for destroying waste by plasma technique
US4615285A (en) * 1984-09-21 1986-10-07 Skf Steel Engineering, Ab Method of destroying hazardous wastes
US4862814A (en) * 1987-08-13 1989-09-05 The University Of Sydney Pulverized fuel burner
FR2635850A1 (fr) * 1988-09-01 1990-03-02 Electricite De France Dispositif de combustion assistee par plasma

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4240784A (en) * 1978-09-25 1980-12-23 Dauvergne Hector A Three-stage liquid fuel burner
US4381718A (en) * 1980-11-17 1983-05-03 Carver George P Low emissions process and burner
US4509434A (en) * 1981-02-27 1985-04-09 Villamosipari Kutato Intezel Procedure and equipment for destroying waste by plasma technique
US4615285A (en) * 1984-09-21 1986-10-07 Skf Steel Engineering, Ab Method of destroying hazardous wastes
US4862814A (en) * 1987-08-13 1989-09-05 The University Of Sydney Pulverized fuel burner
FR2635850A1 (fr) * 1988-09-01 1990-03-02 Electricite De France Dispositif de combustion assistee par plasma

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999019668A1 (fr) * 1997-10-10 1999-04-22 Kvaerner Pulping Oy Procede et agencement pour optimiser l'oxydation pendant la combustion de carburants gazeux et liquides
US6109911A (en) * 1997-10-10 2000-08-29 Kvaerner Pulping Oy Method and arrangement for optimizing oxidation during burning of gaseous and liquid fuels
WO2002068872A1 (fr) 2001-02-27 2002-09-06 Yantai Longyuan Power Technology Co., Ltd. Ensemble cathode et allumeur a plasma pourvu d'un tel ensemble cathode
EP1371905A1 (fr) * 2001-02-27 2003-12-17 Yantai Longyuan Power Technology Co. Ltd. Ensemble cathode et allumeur a plasma pourvu d'un tel ensemble cathode
EP1371905A4 (fr) * 2001-02-27 2006-07-05 Yantai Longyuan Power Technolo Ensemble cathode et allumeur a plasma pourvu d'un tel ensemble cathode
US7281478B2 (en) 2001-02-27 2007-10-16 Yan Tai Long Yuan Electric Technology Co., Ltd. Assembled cathode and plasma igniter with such cathode
CN101749700A (zh) * 2010-03-04 2010-06-23 郑平安 一种煤粉炉微油点火燃烧方法
DE102015104401A1 (de) 2015-03-24 2015-05-07 Mitsubishi Hitachi Power Systems Europe Gmbh Verfahren zur Verminderung von NOx-Emissionen bei der Verbrennung von staubförmigem Brennstoff
DE102015104406A1 (de) 2015-03-24 2015-05-21 Mitsubishi Hitachi Power Systems Europe Gmbh Verfahren zur Verminderung von NOx-Emissionen bei der Verbrennung von staubförmigem Brennstoff

Also Published As

Publication number Publication date
CN1059021A (zh) 1992-02-26
FI87949B (fi) 1992-11-30
PL291046A1 (en) 1992-08-10
FI903548A0 (fi) 1990-07-13
AU8093091A (en) 1992-02-04
FI903548A (fi) 1992-01-14
FI87949C (fi) 1993-03-10

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