CN108426247B

CN108426247B - Fuel nozzle cooling structure of heat accumulation combustor

Info

Publication number: CN108426247B
Application number: CN201711212217.9A
Authority: CN
Inventors: 河本祐作; 北村和也; 川端健介
Original assignee: Chugai Ro Co Ltd
Current assignee: Chugai Ro Co Ltd
Priority date: 2017-02-14
Filing date: 2017-11-27
Publication date: 2020-09-01
Anticipated expiration: 2037-11-27
Also published as: KR20180093790A; TW201829964A; TWI755441B; JP6483169B2; CN108426247A; KR102344215B1; JP2018132222A

Abstract

The invention provides a fuel nozzle cooling structure of a heat accumulation burner, which can reduce the equipment cost and the required installation space required by cooling a fuel nozzle by using an exhaust blower for exhausting in an exhaust operation mode, and has simple arrangement of a pipeline and the like. The heat accumulation burner alternately repeats an exhaust mode and a combustion mode, and the fuel nozzle cooling structure of the heat accumulation burner includes: a hollow cylindrical fuel nozzle which is provided inside the burner body and which injects fuel mixed with combustion air from a tip end thereof to generate a flame; a cooling pipe provided so as to surround an outer periphery of the fuel nozzle, and having a communication portion for communicating with an exhaust system and an opening portion that opens to the atmosphere; and a connection pipe that connects the communication portion and the exhaust system, and cools the fuel nozzle by the atmosphere that flows toward the communication portion through the opening portion by an exhaust suction action of the exhaust system via the connection pipe.

Description

Fuel nozzle cooling structure of heat accumulation combustor

Technical Field

The present invention relates to a fuel nozzle cooling structure for a regenerative combustor, which can reduce the equipment cost and the required installation space required for cooling a fuel nozzle and simplify the arrangement of piping and the like by using an exhaust blower for exhausting in an exhaust operation mode.

Background

Various furnaces using regenerative burners are known (see patent document 1), and in this case, a structure for cooling the regenerative burners is also known (see patent documents 2 and 3). The "industrial furnace, method for energy-saving operation of the industrial furnace, and method for modifying the industrial furnace" of patent document 1 includes: an exhaust pipe connecting the combustion chamber with the chimney; an intake on-off valve that opens to introduce external Air (ATM) into the exhaust pipe; and an impeller connected to a suction blower functioning as a generator (generator), and configured to generate power by being rotated by external air introduced from the open intake opening/closing valve and flowing through the exhaust pipe. In patent document 1, the combustion operation and the exhaust operation of a pair of two regenerative burners are alternately switched.

The "low NOx burner for high-temperature air" of patent document 2 is configured such that a Baffle (pocket) is fitted externally to a tip end portion of a fuel nozzle for injecting fuel, a slit-shaped secondary air supply hole is formed in an outer periphery of the Baffle, the fuel nozzle is configured as a double pipe having an inner periphery portion as a fuel passage and an outer periphery portion as a cooling air passage, a fuel and cooling air ejection hole is provided in a center of the Baffle, a plurality of primary air supply holes having an angle of 30 to 50 ° are provided in a plane having the same pitch circle diameter from an inlet toward an outlet in an outer periphery side of the ejection hole, and ejection holes for fuel, cooling air, and primary air are formed in outlets of the ejection hole and the primary air supply hole. In the burner of patent document 2, air for cooling the fuel nozzle is discharged into the furnace.

In the "cooling device for a regenerative burner fuel nozzle pipe" of patent document 3, there is a problem that the introduced air is not discharged into the furnace but is used only for cooling the cooling air pipe, and the cooling air pipe is cooled while reciprocating forward and forward, thereby effectively preventing overheating of the cooling air pipe. In patent document 3, a blower is required to be provided to send the introduced air to the air cooling pipe without discharging the introduced air for cooling into the furnace.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-133255

Patent document 2: japanese laid-open patent publication No. 10-185128

Patent document 3: japanese patent laid-open publication No. 2001 and 182915

Disclosure of Invention

Problems to be solved by the invention

In view of the fact that the furnace atmosphere heated by the regenerative burner is preferably homogeneous without fluctuation, it is preferable to use the double-tube structure of patent document 3 in which the introduced air is not discharged into the furnace as the cooling structure of the fuel nozzle provided in the regenerative burner.

However, patent document 3 does not disclose how to supply the introduced air to the air-cooling duct. In general, it is considered that a blower is newly or additionally provided, and the introduced air is supplied from the blower to the air supply pipe. When a blower is newly installed, there are problems that equipment costs including piping are incurred and installation space needs to be secured.

The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a fuel nozzle cooling structure for a regenerative combustor, which can reduce the equipment cost and installation space required for cooling the fuel nozzle and simplify the layout of piping and the like by using an exhaust blower that exhausts in an exhaust operation mode.

Means for solving the problems

In a fuel nozzle cooling structure of a heat storage burner according to the present invention, the heat storage burner alternately repeats an exhaust mode in which in-furnace exhaust gas sucked from a burner port of a burner main body by an exhaust suction action of an exhaust system having an exhaust blower is circulated to a heat storage portion to store waste heat, and a combustion mode in which a flame generated from combustion air heated by circulating the combustion air to the heat storage portion is ejected from the burner port of the burner main body into a furnace, the fuel nozzle cooling structure of the heat storage burner includes: a hollow cylindrical fuel nozzle which is provided inside the burner main body and which injects fuel mixed with combustion air from a tip end thereof to generate a flame; a cooling pipe provided so as to surround an outer periphery of the fuel nozzle, and having a communication portion for communicating with the exhaust system and an opening portion that opens to the atmosphere; and a connection pipe that connects the communication portion and the exhaust system, and cools the fuel nozzle by the atmosphere that flows toward the communication portion through the opening portion by an exhaust suction action of the exhaust system via the connection pipe.

Further, in the fuel nozzle cooling structure of the heat accumulating burner of the present invention, the heat accumulating burner alternately repeats an exhaust mode in which an exhaust valve for opening and closing an exhaust system having an exhaust blower is opened and an air supply valve for opening and closing an air supply system having an air supply blower is closed, furnace exhaust gas sucked from a burner port of a burner main body by an exhaust suction action of the exhaust system is circulated to a heat accumulating portion to accumulate waste heat and is discharged to the exhaust system via the exhaust valve, and a combustion mode in which the exhaust valve is closed and the air supply valve is opened, combustion air supplied to the burner main body by the air supply action of the air supply system is circulated to the heat accumulating portion to be heated, and flame generated by the heated combustion air is ejected into a furnace from the burner port of the burner main body, the fuel nozzle cooling structure of the regenerative combustor is characterized by comprising: a hollow cylindrical fuel nozzle which is provided inside the burner main body and which injects fuel mixed with combustion air from a tip end thereof to generate a flame; a cooling pipe provided so as to surround an outer periphery of the fuel nozzle, and having a communication portion for communicating with the exhaust system and an opening portion that opens to the atmosphere; and a connection pipe connecting the communication portion and the exhaust system at an intermediate position between the heat storage portion and the exhaust valve, wherein the fuel nozzle is cooled by atmospheric air flowing toward the communication portion through the opening portion by an exhaust suction action of the exhaust system via the connection pipe in an exhaust mode, and the fuel nozzle is cooled by combustion air bypassing the heat storage portion and flowing toward the opening portion through the communication portion via the connection pipe by an air supply action of the air supply system in a combustion mode.

The fuel nozzle cooling structure for a regenerative combustor is characterized in that the communication portion and the opening portion of the cooling pipe are formed on a base end portion side on a side opposite to a tip end portion of the fuel nozzle, and the cooling pipe includes: a first flow path that surrounds the periphery of the fuel nozzle, is formed from a distal end side to a proximal end side in a longitudinal direction thereof, and communicates with the communication portion; a second flow path that surrounds the periphery of the first flow path, is formed from a distal end side to a proximal end side in a longitudinal direction of the fuel nozzle, and communicates with the opening; and a connection flow path that connects the first flow path and the second flow path on a front end side of the fuel nozzle.

The fuel nozzle cooling structure for a regenerative combustor is characterized by comprising a pair of regenerative combustors, one of which is operated in a combustion mode and the other of which is operated in an exhaust mode, wherein the exhaust systems of the regenerative combustors are joined at a junction, and a single exhaust blower is provided downstream of the junction.

Effects of the invention

In the fuel nozzle cooling structure of the regenerative combustor according to the present invention, the exhaust blower that exhausts gas in the exhaust operation mode is used, so that the facility cost and the installation space required for cooling the fuel nozzle can be reduced, and the arrangement of piping and the like can be simplified.

Drawings

Fig. 1 is a configuration diagram showing a first embodiment of a fuel nozzle cooling structure of a regenerative combustor of the present invention.

Fig. 2 is a structural view showing a second embodiment of a fuel nozzle cooling structure of the regenerative combustor of the present invention.

Description of the reference numerals

1L, 1R regenerative burners; 2L and 2R fire holes; a 3L, 3R burner body; 3a the other end of the burner body; 4L, 4R heat storage portions; 4a one end of the heat storage portion; 4b the other end of the heat storage portion; 5, furnace; 6L, 6R fuel nozzles; 6a the front end of the fuel nozzle is open; 6b base end of fuel nozzle; 8L, 8R cooling pipes; 9L, 9R fuel on-off valve; 10 a fuel supply system; 11 an air supply blower; 12L, 12R air supply valves; 13 an air supply system; 13a combustion air supply pipe; 13b a combustion air merging portion; 13c a combustion air supply main pipe; 14 an exhaust blower; 15L, 15R exhaust valves; 16 an exhaust system; 16a an exhaust pipe; 16b an exhaust merging section; 16c an exhaust main pipe; a 17L, 17R connecting tube; 19 an inner tube; 19a closed end plate; 20 an outer tube; 20a first sealed end plate; 20b a second sealed end plate; 21 an opening part; 22 a communication part; 23 a first flow path; 24 a second flow path; 25 connecting the flow path; 26L, 26R connecting pipes; e, exhausting; f, flame.

Detailed Description

Hereinafter, preferred embodiments of a fuel nozzle cooling structure of a regenerative combustor according to the present invention will be described in detail with reference to the accompanying drawings. Fig. 1 is a structural view showing a fuel nozzle cooling structure of the regenerative combustor of the first embodiment.

As shown in fig. 1, the

regenerative burners

1L and 1R include, as is well known in the art: burner bodies 3L,

3R having burners

2L, 2R at one end facing the inside of the furnace 5; and

heat accumulating portions

4L and 4R provided adjacent to and directly connected to the burner bodies 3L and 3R at the other ends 3a of the burner bodies 3L and 3R, wherein the

heat accumulating burners

1L and 1R are operated so that a pair of opposed combustion modes in which a flame F is ejected from the

ports

2L and 2R of the burner bodies 3L and 3R into the furnace 5 to heat the inside of the furnace 5 (for example, about 1000 ℃) and an exhaust mode in which the exhaust gas E in the furnace 5 is sucked and discharged from the

ports

2L and 2R are alternately and repeatedly switched.

In the

heat storage burners

1L and 1R, in the exhaust mode, the exhaust gas E is sucked from the furnace 5 by the exhaust gas suction action of the exhaust system 16 having the exhaust blower 14, and the sucked exhaust gas E flows to the

heat storage portions

4L and 4R, whereby the waste heat of the exhaust gas E is stored in the

heat storage portions

4L and 4R, so that the exhaust gas E having passed through the

heat storage portions

4L and 4R is cooled (for example, about 200 ℃) and discharged to the exhaust system 16, and thereafter, when the operation is switched from the exhaust mode to the combustion mode, the combustion air flows to the

heat storage portions

4L and 4R by the air supply action of the air supply system 13 having the air supply blower 11, and the combustion air is preheated (heated) by the waste heat of the exhaust gas E stored in the

heat storage portions

4L and 4R.

The preheated combustion air is supplied to the burner bodies 3L and 3R, and is mixed with fuel gas supplied through the

fuel nozzles

6L and 6R provided inside the burner bodies 3L and 3R and burned, whereby the burner bodies 3L and 3R generate flames F through an energy-saving operation using waste heat.

In the case of using the

regenerative burners

1L, 1R, the

burners

1L, 1R are used in a pair so that the furnace temperature does not fluctuate with mode switching between the combustion mode and the exhaust mode.

The operation control is performed such that when one of the heat accumulation burners 1L (1R) is in the combustion mode, the other heat accumulation burner 1R (1L) is operated in the exhaust mode, and when the former is switched to the exhaust mode, the latter is switched to the combustion mode.

In the illustrated example, a pair of burner bodies 3L and 3R are provided on the left and right furnace side walls facing each other among the furnace walls constituting the furnace 5 having a rectangular cross section. The pair of burner bodies may be disposed adjacent to the same wall surface.

As shown in fig. 1, in the fuel nozzle cooling structure of the heat accumulation burner of the present embodiment, a pair of left and right

heat accumulation burners

1L and 1R each include: burner bodies 3L, 3R in the form of

passages having ports

2L, 2R open into the furnace 5 at one end;

heat storage portions

4L, 4R having one ends 4a connected to the other ends 3a of the burner main bodies 3L, 3R; hollow and

simple fuel nozzles

6L, 6R which are provided so as to penetrate the other end 3a side of the burner bodies 3L, 3R and be inserted from the outside into the burner bodies 3L, 3R, have tip end openings 6a facing the

ports

2L, 2R, and eject fuel such as fuel gas mixed with combustion air from the tip end openings 6a toward the

ports

2L, 2R to generate flames F;

cooling pipes

8L and 8R provided so as to surround the outer peripheries of the

fuel nozzles

6L and 6R, penetrating the other ends 3a of the burner bodies 3L and 3R, and extending from the outer portions thereof into the burner bodies 3L and 3R to the front end openings 6a of the

fuel nozzles

6L and 6R or the vicinity thereof; a fuel supply system 10 having on-off

valves

9L and 9R for fuel (in the figure, white open is shown as open, and black solid is shown as closed) for controlling supply/stop of fuel, and connected to the

fuel nozzles

6L and 6R on the side of the base ends 6b of the

fuel nozzles

6L and 6R opposite to the front end opening 6a on one end side in the longitudinal direction, so as to supply fuel toward the front end openings 6a of the

fuel nozzles

6L and 6R; an air supply system 13 which has an air supply blower 11 for supplying combustion air to the burner bodies 3L and 3R and

air supply valves

12L and 12R (white open and black solid are shown as open and closed in the figure) which are openable and closable to control supply and stop of the combustion air, and which is connected to the other end 4b of each

heat storage portion

4L and 4R to supply the combustion air to the

heat storage portions

4L and 4R; and an exhaust system 16 having an exhaust blower 14 for sucking the exhaust gas E from the furnace 5 through the

ports

2L and 2R and discharging the exhaust gas E to the outside of the furnace 5, and openable and

closable exhaust valves

15L and 15R (in the figure, white open is shown as open, and black solid is shown as closed) for controlling the discharge and stop of the exhaust gas E, and connected to the other ends 4b of the

heat storage portions

4L and 4R so as to allow the exhaust gas E flowing out of the

heat storage portions

4L and 4R to flow therethrough.

In detail, the air supply system 13 includes: a pair of combustion air supply pipes 13a directly connected to the

heat storage portions

4L and 4R of the pair of

heat storage burners

1L and 1R, respectively, and through which the combustion air supplied to the

heat storage portions

4L and 4R flows, respectively; a combustion air merging portion 13b for merging the combustion air supply pipes 13 a; and a combustion air supply main pipe 13c connected to each combustion air supply pipe 13a via a combustion air merging portion 13b, wherein an air supply blower 11 is provided in the combustion air supply main pipe 13c to supply combustion air to both the pair of

regenerative burners

1L and 1R, and

air supply valves

12L and 12R are provided in the combustion air supply pipe 13a to individually switch the operation mode of the pair of

regenerative burners

1L and 1R.

In the heat storage combustor 1R (1L) in the combustion mode, the exhaust valve 15R (15L) is closed and the air supply valve 12R (12L) is opened, and the combustion air fed by the air supply action of the air supply system 13 flows to the heat storage portion 4R (4L) through the air supply valve 12R (12L), and is further supplied from the heat storage portion 4R (4L) toward the burner port 2R (2L) of the combustor main body 3R (3L).

In detail, the exhaust system 16 includes: a pair of exhaust pipes 16a directly connected to the

heat storage portions

4L and 4R of the pair of

heat storage burners

1L and 1R, respectively, and through which the exhaust gas E discharged from the

heat storage portions

4L and 4R flows, respectively; an exhaust merging portion 16b for merging the exhaust pipes 16a with each other; and an exhaust main pipe 16c connected to the exhaust pipes 16a via an exhaust merging portion 16b, the exhaust main pipe 16c being provided with an exhaust blower 14 for discharging the exhaust E from both of the pair of

heat accumulation burners

1L, 1R, and the exhaust pipes 16a being provided with

exhaust valves

15L, 15R for individually switching the operation modes of the pair of

heat accumulation burners

1L, 1R.

In the heat storage combustor 1L (1R) in the exhaust mode, the exhaust valve 15L (15R) is opened and the air supply valve 12L (12R) is closed, and the exhaust gas E sucked by the exhaust suction action of the exhaust system 16 flows from the burner port 2L (2R) of the combustor main body 3L (3R) to the heat storage portion 4L (4R), and is further discharged from the heat storage portion 4L (4R) to the exhaust system 16 via the exhaust valve 15L (15R).

When the

heat accumulation burners

1L and 1R are in the combustion mode, the fuel on-off

valves

9L and 9R are opened to supply fuel to the

fuel nozzles

6L and 6R, and when in the exhaust mode, the fuel on-off

valves

9L and 9R are closed to stop the supply of fuel.

When the

heat accumulation burners

1L and 1R are in the combustion mode, the

air supply valves

12L and 12R are opened to supply combustion air to the

ports

2L and 2R of the burner bodies 3L and 3R through the

heat accumulation portions

4L and 4R, and when the exhaust mode is in the exhaust mode, the

air supply valves

12L and 12R are closed to stop the supply of combustion air.

When the

heat storage burners

1L, 1R are in the exhaust mode, the

exhaust valves

15L, 15R are opened to suck the exhaust gas E in the furnace 5 from the

ports

2L, 2R of the burner main bodies 3L, 3R through the

heat storage portions

4L, 4R, and when in the combustion mode, the

exhaust valves

15L, 15R are closed to stop the suction of the exhaust gas E. The air supply blower 11 and the air exhaust blower 14 are normally operated at all times during the operation of the furnace 5.

In the present embodiment, in contrast to the basic configuration of the

heat accumulating burners

1L, 1R described above, each of the

heat accumulating burners

1L, 1R includes a cooling structure that is disposed so as to face the high-

temperature fire ports

2L, 2R and cools the

fuel nozzles

6L, 6R through which the high-temperature exhaust gas E flows around the cooling structure. The cooling structure of the

fuel nozzles

6L, 6R mainly includes the

cooling pipes

8L, 8R and the

connection pipes

17L, 17R that connect the

cooling pipes

8L, 8R to the exhaust system 16.

The

cooling pipes

8L, 8R include an inner pipe 19, an outer pipe 20, an opening 21, and a communicating portion 22, the inner pipe 19 surrounding the outer periphery of the

fuel nozzles

6L, 6R and being formed in a tubular shape in the longitudinal direction from the front end opening 6a side to the base end portion 6b side, the base end portion of the

fuel nozzles

6L, 6R outside the burner bodies 3L, 3R being closed by an annular closed end plate 19a joined to the outer peripheral surfaces of the

fuel nozzles

6L, 6R and being open at the front end side close to the

burner ports

2L, 2R, the outer pipe 20 surrounding the outer periphery of the inner pipe 19 and being formed in a tubular shape in the longitudinal direction of the

fuel nozzles

6L, 6R from the front end opening 6a side to the base end portion 6b side, the base end portion of the

fuel nozzles

6L, 6R outside the burner bodies 3L, 3R being sealed at the base end portion thereof by an annular first sealing end plate 20a joined to the outer peripheral surface of the inner pipe 19, the front end portion side of the inner tube 19 is covered from the

burner

2L, 2R side at the position of the front end portion opening 6a of the

fuel nozzle

6L, 6R that extends further toward the

burner

2L, 2R side than the inner tube 19, and is sealed by an annular second seal end plate 20b that is joined to the outer peripheral surface of the

fuel nozzle

6L, 6R, the opening portion 21 is formed in the outer tube 20 so as to be open to the atmosphere on the base end portion 6b side of the

fuel nozzle

6L, 6R outside the burner main body 3L, 3R, and the communication portion 22 is formed in the inner tube 19 for communicating with the exhaust system 16.

The

cooling pipes

8L and 8R are provided with: a first flow path 23 which surrounds the outer periphery of the

fuel nozzles

6L and 6R, is formed from the front end opening 6a side to the base end 6b side in the longitudinal direction thereof, and communicates with the communication portion 22; a second flow path 24 which surrounds the outer periphery of the first flow path 23, is formed from the front end opening 6a side to the base end 6b side in the longitudinal direction of the

fuel nozzles

6L and 6R, and communicates with the opening 21; and a connection flow path 25 that connects the first flow path 23 and the second flow path 24 so as to turn back on the side of the distal end opening 6a of the

fuel nozzle

6L, 6R.

That is, the exhaust system 16, which functions as exhaust suction, is open to the atmosphere via the outer periphery of the

fuel nozzles

6L, 6R. The communicating portions 22 of the

cooling pipes

8L and 8R are connected to the exhaust system 16 via the connecting

pipes

17L and 17R, and in the present embodiment, the communicating portions 22 of the

cooling pipes

8L and 8R are connected to the exhaust main pipe 16c on which the exhaust blower 14 is provided singly, on the downstream side of the exhaust merging portion 16b where the exhaust pipes 16a from the respective

heat storage portions

4L and 4R merge together. The connection positions of the

connection pipes

17L, 17R of the

regenerative burners

1L, 1R with respect to the exhaust system 16 may be connected at any positions as long as they are intermediate positions between the

exhaust valves

15L, 15R and the exhaust blower 14.

Next, the operation of the fuel nozzle cooling structure of the regenerative combustor of the first embodiment will be described. During operation of the furnace 5, for example, as shown in fig. 1, in the regenerative burner 1R on one side (right side), the on-off valve 9R for fuel and the air supply valve 12R are opened and the exhaust valve 15R is closed to set a combustion mode, while in the regenerative burner 1L on the other side (left side), the on-off valve 9L for fuel and the air supply valve 12L are closed and the exhaust valve 15L is opened to set an exhaust mode. The operation of the

regenerative burners

1L and 1R itself is known as described above.

The exhaust gas E, which flows through the heat storage portion 4L of the heat storage combustor 1L in the exhaust mode by the exhaust suction action of the exhaust blower 14, is stored in the heat storage portion 4L and cooled, reaches the exhaust blower 14 via the open exhaust valve 15L, and is discharged.

The exhaust suction action of the exhaust blower 14 acts on the communicating portion 22 of each of the

cooling pipes

8L and 8R from the exhaust main pipe 16c via the two connecting

pipes

17L and 17R. Since the communication portion 22 communicates with the opening 21 that is open to the atmosphere via the first flow path 23, the connection flow path 25, and the second flow path 24, the atmosphere flows through the opening 21 into the cooling

pipes

8L and 8R on both sides toward the communication portion 22 by the exhaust suction action of the exhaust blower 14.

The ambient air at a temperature much lower than the temperature (about 1000 ℃) of the one end 4a of the

heat accumulating portion

4L, 4R flows from the opening 21 on the base end side of the

cooling pipe

8L, 8R of both the pair of

heat accumulating burners

1L, 1R toward the second flow path 24 in the outer pipe 20 through the opening 6a at the tip end of the

fuel nozzle

6L, 6R provided in both the pair of

heat accumulating burners

1L, 1R in the combustion mode and the exhaust mode facing the

burner

2L, 2R in the furnace 5 and in a high temperature state, and is further circulated through the first flow path 23 in the inner tube 19 after being folded back by the connecting flow path 25, the

fuel nozzles

6L, 6R of the

heat accumulating burners

1L, 1R are cooled, and after cooling, of course, the exhaust gas E is sucked and discharged from the communicating portion 22 to the exhaust system 16 through which the exhaust gas E flows by the exhaust suction action of the single exhaust blower 14 without flowing into the furnace 5.

Even if the left heat accumulation burner 1L is switched to the combustion mode and the right heat accumulation burner 1R is switched to the exhaust mode, the left and

right fuel nozzles

6L, 6R are always cooled by the air introduced by the exhaust suction action during the operation of the exhaust blower 14.

In the fuel nozzle cooling structure of the heat storage combustor of the first embodiment described above, the heat storage combustor 1L, 1R alternately repeats an exhaust mode in which waste heat is stored by circulating furnace exhaust gas E sucked from the ports 2L, 2R of the combustor main bodies 3L, 3R by an exhaust suction action of the exhaust system 16 having the exhaust blower 14 to the heat storage portions 4L, 4R provided adjacent to and directly connected to the combustor main bodies 3L, 3R, and a combustion mode in which flames F generated from combustion air heated by circulating to the heat storage portions 4L, 4R are ejected from the ports 2L, 2R of the combustor main bodies 3L, 3R into the furnace 5, the heat storage combustor 1L, 1R including: hollow and simple fuel nozzles 6L and 6R which are provided inside the burner bodies 3L and 3R and which inject fuel mixed with combustion air into the furnace 5 from the tip end openings 6a thereof to generate flames F; cooling pipes 8L and 8R provided so as to surround the outer peripheries of the fuel nozzles 6L and 6R, and having a communication portion 22 for communicating with the exhaust system 16 and an opening portion 21 that opens to the atmosphere; and connection pipes 17L, 17R that connect the communication portion 22 with the exhaust system 16, and cool the fuel nozzles 6L, 6R through the opening portion 21 by the exhaust suction action of the exhaust system 16 via the connection pipes 17L, 17R, so that the fuel nozzles 6L, 6R can be cooled by flowing the cooling air into the cooling pipes 8L, 8R by the exhaust blower 14 that discharges the exhaust gas E in the exhaust mode, thermal deformation of the fuel nozzles 6L, 6R can be prevented, and further, the equipment required for cooling the fuel nozzles 6L, 6R only needs the cooling pipes 8L, 8R surrounding the fuel nozzles 6L, 6R and the connection pipes 17L, 17R that connect the cooling pipes 8L, 8R with the exhaust system 16, so that the equipment cost and the required installation space can be reduced, only the spatial extent of the tubes is required and the arrangement is therefore also simple.

The communicating portions 22 and the openings 21 of the cooling

pipes

8L and 8R are formed on the base end portion 6b side opposite to the front end portion openings 6a of the

fuel nozzles

6L and 6R, and the

cooling pipes

8L and 8R include: a first flow path 23 which surrounds the outer periphery of the

fuel nozzles

6L and 6R, and communicates with the opening 21; and a connection channel 25 that connects the first channel 23 and the second channel 24 to each other on the side of the distal end opening 6a of the

fuel nozzle

6L, 6R, so that the atmosphere can be circulated and reciprocated from the second channel 24 to the first channel 23 in the longitudinal direction of the

fuel nozzle

6L, 6R to ensure a cooling effect, and the atmosphere for cooling can be efficiently cooled without being released into the furnace 5, thereby preventing the atmosphere in the furnace from varying.

The

heat storage burners

1L and 1R are provided with a pair of

heat storage burners

1L and 1R that operate in the exhaust mode when one is in the combustion mode, and the exhaust systems 16 of the

heat storage burners

1L and 1R are joined together at the exhaust joining portion 16b, and the single exhaust blower 14 is provided downstream of the exhaust joining portion 16b, so even in the furnace 5 that operates by the pair of

heat storage burners

1L and 1R, it is possible to ensure the alternate combustion operation by cooling both the

fuel nozzles

6L and 6R by the single exhaust blower 14.

In the description of the present embodiment, the case where the

heat storage burners

1L and 1R are applied to a pair has been described, but the heat storage burners are not limited to a pair, and the above-described operational effects can be obtained even if the heat storage burners are single bodies.

Fig. 2 is a structural view showing a fuel nozzle cooling structure of the regenerative combustor of the second embodiment. The connecting

pipes

26L, 26R of the second embodiment are different in connecting position with respect to the exhaust system 16, and thus different in function, as compared with the first embodiment described above.

In the first embodiment, the

connection pipes

17L, 17R from the communication portion 22 are connected to the exhaust main pipe 16c, but in the second embodiment, the

connection pipes

26L, 26R from the communication portion 22 are connected to intermediate positions between the

heat storage portions

4L, 4R provided adjacent to and directly connected to the burner main bodies 3L, 3R and the

exhaust valves

15L, 15R in the

heat storage burners

1L, 1R, respectively. The other structure is the same as that of the first embodiment.

The operation of the fuel nozzle cooling structure of the regenerative combustor of the second embodiment will be described. As described above, the

regenerative burners

1L, 1R are, in the combustion mode, at a higher temperature in the vicinity of the tip end opening 6a of the

fuel nozzles

6L, 6R facing the

ports

2L, 2R where the flames F are generated than in other portions of the

fuel nozzles

6L, 6R, and in the exhaust mode, the flames F are extinguished, but high-temperature exhaust gas E flows around the

fuel nozzles

6L, 6R.

Therefore, it is preferable that the cooling of the

fuel nozzles

6L and 6R by the cooling

pipes

8L and 8R be performed at a low temperature on the inner pipe 19 side in the combustion mode and at a low temperature on the outer pipe 20 side in the exhaust mode.

In the second embodiment, since the connection positions of the

connection pipes

26L, 26R with respect to the exhaust system 16 are connected to the intermediate positions of the

heat storage portions

4L, 4R and the

exhaust valves

15L, 15R, in the exhaust mode (shown by the operation of the heat storage combustor 1L on the left in the figure), the atmospheric air that passes through the opening portion 21 by the exhaust suction action of the exhaust system 16 via the connection pipe 26L and flows toward the communication portion 22 first flows through the outer pipe 20 and then flows through the inner pipe 19, as in the first embodiment, whereby the outer pipe 20 exposed to the exhaust gas E can be cooled more efficiently by the atmospheric air at a lower temperature, and thus the fuel nozzle 6L can be cooled appropriately to prevent overheating.

On the other hand, in the combustion mode (shown by the operation of the heat accumulating combustor 1R on the right in the figure), unlike the first embodiment described above, among the combustion air supplied toward the heat accumulating portion 4R by the air supply action of the air supply system 13 having the air supply blower 11, a part of the combustion air bypasses the heat accumulating portion 4R, flows into the connecting pipe 26R through the exhaust system 16 (exhaust pipe 16a) in which the exhaust valve 15R is closed, then flows toward the opening portion 21 through the connecting pipe 26R and the communicating portion 22, and the part of the combustion air flows through the inner pipe 19 first and then flows through the outer pipe 20, whereby the inner pipe 19 exposed to the flame F can be cooled more efficiently by the combustion air of a lower temperature, and the fuel nozzle 6R can be cooled appropriately to prevent overheating.

That is, the flow direction in the

cooling pipes

8L and 8R changes with respect to the switching of the operation conditions such as the combustion mode and the exhaust mode, and thus a good cooling effect of the

fuel nozzles

6L and 6R can be ensured.

Further, since the

connection pipes

26L and 26R are only required to be disposed between the burner bodies 3L and 3R and the

heat storage portions

4L and 4R, which are directly connected to each other in an adjacent manner, it is not necessary to extend the

connection pipes

17L and 17R at least to the downstream side of the

exhaust valves

15L and 15R as in the first embodiment, and therefore, the space for the pipes can be reduced, and the cost of the equipment and the size of the equipment layout can be reduced.

In the second embodiment, the above-described operation and effect can be obtained not only by applying the

heat accumulation burners

1L and 1R to a pair of heat accumulation burners but also by using only one heat accumulation burner. The second embodiment may have other operational effects of the first embodiment.

Claims

1. A fuel nozzle cooling structure of a heat storage burner that alternately repeats an exhaust mode in which exhaust gas in a furnace, which is sucked from a burner port of a burner body by an exhaust suction action of an exhaust system having an exhaust blower, is circulated to a heat storage portion to store waste heat, and a combustion mode in which a flame generated from combustion air, which is circulated to the heat storage portion and heated, is ejected from the burner port of the burner body into the furnace,

the fuel nozzle cooling structure of the heat accumulation burner comprises: a hollow cylindrical fuel nozzle which is provided inside the burner main body and which injects fuel mixed with combustion air from a tip end thereof to generate a flame; a cooling pipe provided so as to surround an outer periphery of the fuel nozzle, and having a communication portion for communicating with the exhaust system and an opening portion that opens to the atmosphere; and a connection pipe connecting the communication portion with the exhaust system,

the fuel nozzle is cooled by the atmosphere flowing toward the communication portion through the opening portion by an exhaust suction action of the exhaust system via the connection pipe.

2. The fuel nozzle cooling structure of the regenerative combustor according to claim 1,

the communication portion and the opening portion of the cooling pipe are formed on a base end portion side opposite to the fuel nozzle tip portion, and the cooling pipe includes: a first flow path that surrounds the periphery of the fuel nozzle, is formed from a distal end side to a proximal end side in a longitudinal direction thereof, and communicates with the communication portion; a second flow path that surrounds the periphery of the first flow path, is formed from a distal end side to a proximal end side in a longitudinal direction of the fuel nozzle, and communicates with the opening; and a connection flow path that connects the first flow path and the second flow path on a front end side of the fuel nozzle.

3. The fuel nozzle cooling structure of the regenerative combustor according to claim 1 or 2,

the fuel nozzle cooling structure of the heat accumulation burner includes a pair of the heat accumulation burners operated in an exhaust mode when one of the heat accumulation burners is in a combustion mode, and the exhaust systems of the heat accumulation burners are joined to each other at a junction portion, and a single exhaust blower is provided downstream of the junction portion.

4. A fuel nozzle cooling structure of a heat accumulation burner that alternately repeats an exhaust mode in which an exhaust valve that opens and closes an exhaust system having an exhaust blower is opened and an air supply valve that opens and closes an air supply system having an air supply blower is closed, and that circulates in-furnace exhaust gas that is drawn from a burner port of a burner body by an exhaust suction action of the exhaust system to a heat accumulation portion to accumulate waste heat and discharges the waste heat to the exhaust system via the exhaust valve, and a combustion mode in which the exhaust valve is closed and the air supply valve is opened, and that circulates combustion air that is supplied to the burner body by an air supply action of the air supply system to the heat accumulation portion to be heated, and that ejects a flame generated from the heated combustion air from the burner port of the burner body into a furnace,

the fuel nozzle cooling structure of the heat accumulation burner comprises: a hollow cylindrical fuel nozzle which is provided inside the burner main body and which injects fuel mixed with combustion air from a tip end thereof to generate a flame; a cooling pipe provided so as to surround an outer periphery of the fuel nozzle, and having a communication portion for communicating with the exhaust system and an opening portion that opens to the atmosphere; and a connection pipe connecting the communication portion and the exhaust system at an intermediate position between the heat storage portion and the exhaust valve,

the fuel nozzle is cooled by the atmospheric air flowing through the opening toward the communicating portion by an exhaust suction action of the exhaust system via the connecting pipe in the exhaust mode, and is cooled by the combustion air bypassing the heat storage portion and flowing through the connecting pipe toward the opening via the communicating portion in the combustion mode by an air supply action of the air supply system.

5. The fuel nozzle cooling structure of the regenerative combustor according to claim 4,

6. The fuel nozzle cooling structure of the regenerative combustor according to claim 4 or 5,