JP2012057830A - Regenerative burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a regenerative burner capable of removing nitrogen oxide in exhaust gas with a simple device configuration.SOLUTION: The regenerative burner includes a heat storage part which stores heat by heat recovery from the exhaust gas when the exhaust gas is introduced while preheating a combustion air by releasing heat to the combustion air when the combustion air is introduced instead of the exhaust gas. The heat storage part carries a metal oxide NOx catalyst which removes nitrogen oxide out of the exhaust gas.

Description

  The present invention relates to a regenerative burner used in an industrial furnace.

  In recent years, so-called regenerative burners have been used in industrial furnaces (including heating furnaces, heat treatment furnaces, firing furnaces, etc.) in order to improve thermal efficiency (for example, JP-A-7-293815, (See Kaihei 8-49836, Japanese Patent Laid-Open No. 2008-232474, etc.). In such a heat storage burner, a heat storage body is provided in the air supply / exhaust path.

  As disclosed in Japanese Patent Laid-Open No. 7-293815, etc., this type of industrial furnace is provided with a pair of heat storage burners so as to face each other. The industrial furnace having such a configuration operates as follows.

  While the fuel is combusted in one of the pair of the regenerative burners, the other is exhausted. At this time, heat storage in which the heat stored in the exhaust gas is recovered by the heat storage body is performed in the heat storage body in the other heat storage burner. Thereafter, the one of the pair of regenerative burners is switched from combustion to exhaust, and the other is switched from exhaust to combustion. Then, in the other heat storage burner in which combustion is performed, the combustion air is preheated by the heat storage body.

  Then, by switching between combustion and exhaust in the pair of regenerative burners at a relatively short period, in both the regenerative burners, the heat from the exhaust gas is recovered by the regenerator and the recovered The combustion air is preheated by heat. Thereby, high thermal efficiency can be achieved.

  In addition, this type of regenerative burner is known that includes a denitration means for removing nitrogen oxides in exhaust gas (see, for example, JP-A-7-293815).

  As described in JP-A-7-293815, etc., the denitration means in this type of conventional heat storage burner described above supplies ammonia gas to exhaust gas, and nitrogen oxide and ammonia in the exhaust gas. Is reacted with denitration. For this reason, the conventional regenerative burner with denitration means has an ammonia supply device that complicates the device configuration, increases the device cost (including maintenance costs such as ammonia replenishment), and increases the device space. It was.

  The present invention has been made to cope with such a problem. That is, an object of the present invention is to provide a regenerative burner capable of removing nitrogen oxides in exhaust gas with a simple apparatus configuration.

  The heat storage burner of the present invention includes a heat storage section. The heat storage unit stores heat by recovering heat from the exhaust gas when the exhaust gas is introduced, and releases the combustion air by radiating heat to the combustion air when the combustion air is introduced instead of the exhaust gas. It is configured to preheat the air.

  The feature of the present invention is that the heat storage section carries a metal oxide NOx catalyst for removing nitrogen oxides in the exhaust gas. Specifically, for example, the heat storage unit may be composed of a ceramic carrier and the metal oxide NOx catalyst made of a perovskite complex oxide supported on the carrier.

  The heat storage unit may include a first portion supporting the metal oxide NOx catalyst and a second portion supporting a catalyst for other components that removes other components in the exhaust gas. Specifically, the first portion may include first catalyst particles formed by supporting the metal oxide NOx catalyst on the particulate carrier. The second portion may include second catalyst particles obtained by supporting the catalyst for other components on the particulate carrier. In this case, in order to partition the aggregate of the first catalyst particles and the aggregate of the second catalyst particles, an air-permeable partition member (such as a flat plate or a mesh formed with a large number of through holes) is provided. Can be.

  In the heat storage burner of the present invention having such a configuration, the heat stored in the exhaust gas is recovered by the heat storage body during the heat storage operation. Thereafter, the combustion air is preheated by the heat storage body during the combustion operation.

  When a certain amount of time elapses from the start of operation and the furnace temperature becomes high (for example, 1000 ° C. or higher), nitrogen oxides are generated in the furnace. However, the nitrogen oxide is removed by the metal oxide NOx catalyst in the heat storage body in the heat storage burner that performs a heat storage operation (at this time, the temperature of the heat storage body increases as the furnace temperature rises). The metal oxide NOx catalyst is sufficiently warmed up to remove nitrogen oxides).

  According to the configuration of the present invention, it is possible to satisfactorily remove nitrogen oxides in the exhaust gas without providing an ammonia supply device. Therefore, according to the present invention, the nitrogen oxide in the exhaust gas can be removed with a simple apparatus configuration.

It is a figure showing the outline of the whole composition of the industrial furnace system to which one embodiment of the present invention was applied. It is sectional drawing to which the circumference | surroundings of one (right side in FIG. 1) of a pair of heat storage type burners shown by FIG. 1 were expanded. It is sectional drawing which shows the internal structure of the 1st catalyst particle and 2nd catalyst particle which are shown by FIG.

  Hereinafter, preferred embodiments of the present invention will be described using examples and comparative examples. In addition, the description about the following embodiment is specific to the extent possible, merely an example of the embodiment of the present invention in order to satisfy the description requirement (description requirement / practicability requirement) of the specification required by law. It is only what is described in.

  Therefore, as will be described later, it is quite natural that the present invention is not limited to the specific configurations of the embodiments and examples described below. Examples of the various modifications that can be made to this embodiment or example are inserted into the description of the embodiment, as they interfere with the understanding of the consistent description of the embodiment, and as much as possible. It is listed together at the end.

<Configuration of industrial furnace system>
FIG. 1 is a diagram showing an outline of the overall configuration of an industrial furnace system S (hereinafter simply referred to as “system S”) to which an embodiment of the present invention is applied. The system S of this embodiment is used for degreasing and firing ceramics. Referring to FIG. 1, the system S includes a furnace body 1, a pair of heat storage burners 2, 2, a fuel supply path 3, and an intake / exhaust path 4.

  The furnace body 1 is configured such that a ceramic molded body as an object to be processed can be inserted therein. A pair of regenerative burners 2, 2, which is an embodiment of the present invention, is provided to face each other with the furnace body 1 interposed therebetween. These regenerative burners 2 and 2 are attached to the furnace body 1. A fuel supply path 3 and an intake / exhaust path 4 are connected to each regenerative burner 2.

  Since the specific configurations of the furnace body 1, the fuel supply path 3, and the intake and exhaust path 4 are well known, detailed description thereof will be omitted, and the specific configuration of the regenerative burner 2 in the present embodiment will be described below. To do.

<< Regenerative burner >>
FIG. 2 is an enlarged cross-sectional view of one of the pair of regenerative burners 2 and 2 shown in FIG. 1 (the right side in FIG. 1). It is assumed that the other heat storage burner 2 has the same configuration as the one heat storage burner 2. Hereinafter, a specific configuration of the heat storage burner 2 of the present embodiment will be described with reference to FIG.

  The regenerative burner 2 is attached to the furnace body 1 at a position corresponding to an intake / exhaust port 10 a provided in the furnace wall 10 that forms the side wall of the furnace body 1.

  Inside the burner tile 21 of the heat storage burner 2, a gas passage 21a bent in a substantially L shape in a cross-sectional view is provided. One end of the gas passage 21a on the furnace wall 10 side (the left end in the figure) is connected to the intake / exhaust port 10a.

  A main burner 22 is attached to the burner tile 21. The main burner 22 is an LNG burner that uses LNG (liquefied natural gas) as fuel. The main burner 22 injects LNG as fuel in a direction from the above-described bent portion of the gas passage 21a toward the upstream end in the exhaust gas flow direction (that is, toward the intake / exhaust port 10a). Configuration and arrangement.

  The main burner 22 is connected to the fuel supply path 3. A main fuel injection valve 22 a is interposed at a position corresponding to the main burner 22 in the fuel supply path 3. The main fuel injection valve 22a is opened and closed under the control of a control panel (not shown) so as to switch the presence or absence of fuel injection from the main burner 22.

  The heat storage unit 24 is provided so as to be connected to the end of the gas passage 21a inside the burner tile 21 on the downstream side in the exhaust gas flow direction (upstream side in the combustion air flow direction). The heat storage unit 24 stores heat by heat recovery from the exhaust gas when the heat storage burner 2 performs an exhaust operation, and also releases the combustion air by radiating heat to the combustion air when the heat storage burner 2 performs a combustion operation. Is configured to preheat. The heat storage unit 24 is configured to remove harmful components (such as nitrogen oxides) in the exhaust gas during the above-described heat storage operation.

  Specifically, the heat storage unit 24 includes a denitration catalyst unit 24a, a ceria catalyst unit 24b, and a partition member 24c. The denitration catalyst part 24a, the ceria catalyst part 24b, and the partition member 24c are accommodated in a casing 240 made of a plate-like member in which a large number of circular through holes are formed. The casing 240 is configured to be detachable from the heat storage burner 2. That is, the heat storage unit 24 is configured to be replaceable by attaching / detaching the casing 240 to / from the intake / exhaust path 4.

  The denitration catalyst portion 24a is composed of a large number of first catalyst particles 241a (see FIG. 3). The ceria catalyst portion 24b is composed of a large number of second catalyst particles 241b (see FIG. 3). The partition member 24c is made of a metal mesh having an opening diameter smaller than the particle diameters of the first catalyst particle 241a and the second catalyst particle 241b, and partitions the denitration catalyst part 24a and the ceria catalyst part 24b, thereby The first catalyst particles 241a and the second catalyst particles 241b are provided between the denitration catalyst portion 24a and the ceria catalyst portion 24b so that no alternating current occurs.

  FIG. 3 is a cross-sectional view showing the internal configuration of the first catalyst particles 241a and the second catalyst particles 241b shown in FIG. Referring to FIG. 3, the first catalyst particles 241a are composed of a particulate carrier 242 made of alumina ceramic and a metal oxide NOx catalyst 243a supported on the surface thereof. The second catalyst particles 241b are composed of the same carrier 242 as described above and a ceria catalyst 243b supported around the same.

In the present embodiment, the metal oxide NOx catalyst 243a is made of a perovskite complex oxide having a good nitrogen oxide decomposition activity at a temperature of 800 ° C. or higher. Examples of the metal oxide NOx catalyst 243a include Ba _0.8 La _0.2 Mn _0.8 Mg _0.2 O ₃ and SrFe _0.7 M _0.3 O ₃ (M is Mg, Sn, Ni). (Reference: Catalytic Society of Japan "Direct decomposition of NO using Ba (La) Mn (Mg) based complex oxide" Yusuke Shinna)・ Hiroaki Yano, Hiroshige Matsumoto, Tatsumi Ishihara 2005, The 95th Catalytic Conference, “Effects of additive on NO direct decomposition activity of SrFeO ₃ complex oxide” Yusuke Shinna, Hiroshige Matsumoto, Tatsumi Ishihara 2005 Catalyst debate).

  An air introduction portion 25 is provided at an upstream end portion of the heat storage portion 24 in the exhaust gas flow direction. When the regenerative burner 2 performs an exhaust operation, the air introduction unit 25 sends outside air into the heat storage unit 24 to increase the oxygen concentration inside the heat storage unit 24 and promote combustion of combustible components. To get.

  An air introduction valve 25 a is interposed in the air introduction portion 25. The air introduction valve 25a is opened / closed under the control of a control panel (not shown) to switch the presence / absence of introduction of outside air into the heat storage unit 24 by the air introduction unit 25.

<Effects of Configuration of Embodiment>
Hereinafter, operation | movement of the system S of this embodiment is demonstrated, referring FIGS. 1-3.

  In the system S of the present embodiment, the pair of heat storage burners 2 and 2 alternately repeat combustion and exhaust operations. That is, while one of the pair of regenerative burners 2 and 2 is in a combustion operation, the other is in an exhaust operation. The combustion operation and the exhaust operation in the pair of regenerative burners 2 and 2 are switched at a relatively short cycle.

  In the regenerative burner 2 that performs the combustion operation, the air introduction valve 25a is closed, while the main fuel injection valve 22a is opened. Thus, fuel is injected from the main burner 22 toward the intake / exhaust port 10a, and the interior of the furnace body 1 is heated.

  On the other hand, in the regenerative burner 2 that performs the exhaust operation, the main fuel injection valve 22a is closed. As a result, the exhaust gas discharged from the inside of the furnace body 1 through the intake / exhaust port 10 a flows through the gas passage 21 a in the heat storage burner 2 toward the heat storage unit 24. The air introduction valve 25 a is opened as necessary, so that outside air is introduced into the heat storage unit 24 by the air introduction unit 25. During this exhaust operation, harmful components (nitrogen oxides, CO, etc.) contained in the exhaust gas introduced into the heat storage unit 24 are removed from the denitration catalyst unit 24a and the ceria catalyst unit 24b provided in the heat storage unit 24. Is removed.

  In particular, nitrogen oxide may be generated in the furnace body 1 when the temperature in the furnace body 1 reaches a high temperature (for example, 1000 ° C. or higher) after a lapse of time from the start of the combustion operation. In such a case, since the temperature of the heat storage unit 24 is sufficiently increased as the temperature in the furnace body 1 is increased, the metal oxide NOx catalyst 243a is sufficiently warmed up to remove nitrogen oxides. Yes. Therefore, the nitrogen oxide contained in the exhaust gas introduced into the heat storage unit 24 during the exhaust operation is directly removed (without adding other additives such as ammonia) by the denitration catalyst unit 24a. .

  Thus, in the configuration of the present embodiment, it is possible to satisfactorily remove nitrogen oxides in the exhaust gas without providing an ammonia supply device. Therefore, according to the configuration of the present embodiment, the nitrogen oxide in the exhaust gas can be removed with a simple device configuration.

<List of examples of modification>
In addition, each above-mentioned embodiment is only what the exemplary embodiment of this invention considered as the best at the time of the application of this application for the time being, and was described only by way of illustration. Therefore, the present invention is not limited to the specific configurations and aspects disclosed in the individual embodiments described above. Therefore, it goes without saying that various modifications can be made to the above-described embodiment without departing from the essential part of the present invention.

  Hereinafter, some modifications will be illustrated. Needless to say, the modifications are not limited to those listed below. For example, it is needless to say that a plurality of embodiments and modifications can be applied in combination as appropriate within a technically consistent range.

  The present invention (especially those expressed functionally and functionally in each component constituting the means for solving the problems of the present invention) is described in the above-described embodiments and the following modifications. On the basis of it, it should not be interpreted in a limited way. Such a limited interpretation, while improperly harming the applicant's interests (rushing to file under an earlier application principle), improperly imitates the patent for the protection and use of the invention Contrary to the purpose of the law, it is not allowed.

  For example, the shape of the particulate carrier 242 can be any shape such as a spherical shape, a spheroid shape, a cylindrical shape, a bowl shape, a donut shape, or an indefinite shape. The carrier 242 in the first catalyst particle 241a and the carrier 242 in the second catalyst particle 241b may have the same shape or different shapes. Further, depending on the shape of the carrier 242, the partition member 24c may be omitted. Furthermore, the heat storage unit 24 (the denitration catalyst unit 24a and / or the ceria catalyst unit 24b) can also be configured by supporting a catalyst on a carrier made of a ceramic or metal honeycomb structure such as alumina. Even when one of the denitration catalyst portion 24a and the ceria catalyst portion 24b is in the form of particles and the other is in the form of a honeycomb, the partition member 24c can be omitted.

  As the metal oxide NOx catalyst 243a constituting the denitration catalyst unit 24a, those other than the above specific examples can be widely adopted. Moreover, it can replace with the ceria catalyst part 24b, and what carried the other catalyst can be used. Furthermore, the heat storage unit 24 may have a soot collection function. In addition, as a catalyst provided in the heat storage unit 24, a vehicle exhaust gas purifying catalyst (a so-called three-way catalyst or the like) can be used. In such a case, the denitration catalyst part 24a and the ceria catalyst part 24b can be integrated.

  In addition, what is expressed in terms of function and function in each element constituting the means for solving the problems of the present invention is the specific structure disclosed in the above-described embodiments, examples, and modifications. In addition, any structure capable of realizing the operation / function is included. Furthermore, the contents of the prior application and each publication (including the specification and the drawings) cited in the present specification may be incorporated as appropriate as part of the present specification.

DESCRIPTION OF SYMBOLS S ... Industrial furnace system 1 ... Furnace body 10 ... Furnace wall 10a ... Intake and exhaust port 2 ... Thermal storage burner 21 ... Burner tile 21a ... Gas passage 22 ... Main burner 22a ... Main fuel injection valve 24 ... Thermal storage part 24a ... Denitration catalyst part 24b ... Ceria catalyst part 24c ... partition member 241a ... first catalyst particle 241b ... second catalyst particle 242 ... carrier 243a ... metal oxide NOx catalyst 243b ... ceria catalyst 25 ... air introduction part 25a ... air introduction valve 3 ... fuel supply path 4 ... Intake and exhaust path

Japanese Unexamined Patent Publication No. 7-293815 JP-A-8-49836 JP 2008-232474 A

Claims (5)

Heat storage that stores heat by recovering heat from the exhaust gas when the exhaust gas is introduced, while preheating the combustion air by radiating heat to the combustion air when the combustion air is introduced instead of the exhaust gas In the regenerative burner with
The heat storage burner is characterized in that the heat storage section carries a metal oxide NOx catalyst for removing nitrogen oxides in the exhaust gas. The regenerative burner according to claim 1,
The heat storage unit is
A ceramic carrier;
The metal oxide NOx catalyst comprising a perovskite complex oxide supported on the carrier;
A regenerative burner characterized by comprising: A regenerative burner according to claim 2,
The heat storage unit is
A first portion carrying the metal oxide NOx catalyst;
A second part carrying a catalyst for other components for removing other components in the exhaust gas;
A regenerative burner characterized by comprising: A regenerative burner according to claim 3,
The first portion includes first catalyst particles formed by supporting the metal oxide NOx catalyst on the particulate support.
The regenerative burner, wherein the second part includes second catalyst particles formed by supporting the catalyst for other components on the particulate carrier. A regenerative burner according to claim 4,
A heat storage burner, wherein the heat storage section is provided with a partition member having air permeability for partitioning the aggregate of the first catalyst particles and the aggregate of the second catalyst particles.

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