JP2003254509A - Single end type heat accumulating radiant tube burner and its combustion method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a single end type heat accumulating radiant tube burner which reduces NOx, and saves on energy without damaging a combustion nozzle. <P>SOLUTION: This single end type heat accumulating radiant tube burner is composed of supply-discharge pipes 24a and 24b connected to respective rear end parts of an inner tube 22 arranged at a prescribed interval inside an outer tube 21 having blocked-up one end, and having venturi suction pipes 34a and 34b in a tip part, a bypass pipe 35 having an exhaust gas exhaust port 36 for communicating the supply-discharge pipe, an inner tube fuel nozzle 26 having the double tube constitution for blowing out cooling air from an outer peripheral part of the fuel blown out of a central part arranged in an inner tube central part, an outer tube fuel nozzle 30 having the double tube constitution for blowing out the cooling air from the outer peripheral part of the fuel blown out of central parts arranged in a plurality in an annular space formed of the outer tube and the inner tube, an inner tube heat accumulator R<SB>1</SB>installed between a tip part of an inner tube combustion nozzle and the inner tube, and an outer tube heat accumulator R<SB>2</SB>installed by penetrating through a tip part of an outer tube combustion nozzle. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-end heat storage type radiant tube burner device and a combustion method thereof.

[0002]

2. Description of the Related Art A single-ended radiant tube burner device is applied to heating equipment in which it is difficult to install a U-shaped radiant tube burner device or a W-shaped radiant tube burner device. , For example, JP-A-7-8341
It is proposed in Japanese Patent Publication No. 4 and the like.

That is, as shown in FIG. 2, the single-ended radiant tube burner apparatus T ₁ has an outer tube 1 having a closed tip and an inner tube 2 provided inside the outer tube 1.
And a combustion air supply pipe 3 in the inner pipe 2, and a fuel gas supply pipe 4 in the combustion air supply pipe 3 to form the combustion air. Combustion air is supplied to the passage 5 formed between the supply pipe 3 and the inner pipe 2, and fuel gas is supplied from the fuel gas supply pipe 4 to burn in the combustion chamber 6. After reversing at the closed end of the, the outer pipe 1 is heated through the annular space 7 formed by the outer pipe 1 and the inner pipe 2, and at the same time, the combustion air supplied in opposition to the flow of the combustion exhaust gas. Is preheated and exhausted.

However, as described above, in the structure in which the combustion air supplied in opposition to the flow of the combustion exhaust gas is preheated, the heat transfer area for heat exchange is limited, so that the heat recovery rate depends on the temperature inside the furnace. Was about 65% at 950 ° C, and there was a limit to the heat recovery rate.

Therefore, a single end type heat storage type radiant tube burner apparatus T ₂ having the structure shown in FIG.
It is proposed in Japanese Patent Publication No.-83414.

This single-end type heat storage type radiant tube burner device T ₂ has an outer tube 10 whose tip is closed.
And the inner pipe 11 disposed inside the outer pipe 10 has a double-pipe structure, and the outer pipe heat storage body 12 is provided between the rear ends of the outer pipe 10 and the inner pipe 11.
Is also provided with an inner pipe heat storage body 13 at the rear end of the inner pipe 11,
The rear ends of the outer tube heat storage body 12 and the inner tube heat storage body 13 are provided with a combustion air supply blower 14 or an exhaust blower 15 via a switching valve V.
Communicate with.

In addition, inside the inner pipe 11, the outer pipe 10 and the inner pipe 11
An inner pipe fuel nozzle 17 and an outer pipe fuel nozzle 18 are arranged in a passage 16 formed by the above.

When the combustion air supply blower 14 and the exhaust blower 15 are driven and the switching valve V is set to the state shown in the drawing, fuel gas is supplied from the inner pipe fuel nozzle 17 and ignited, the combustion gas is generated. After heating the outer tube 10 through the passage 16 from the above, the combustion gas passes through the outer tube heat storage body 12 and maximizes the sensible heat of the combustion exhaust gas.

Thereafter, the switching valve V is switched and fuel gas is supplied from the outer pipe fuel nozzle 18. in this case,
Since the combustion air passes through the heated outer tube heat storage body 12 and is sufficiently preheated to be used for combustion, it is possible to realize highly efficient combustion with great energy saving.

After a lapse of a predetermined time, the switching valve V is switched and fuel gas is supplied from the inner pipe fuel nozzle 17 to perform combustion. After that, the above steps are repeated to perform alternating combustion.

[0011]

[Problems to be Solved by the Invention]
Angle end type heat storage type radiant tube burner device T
_TwoIn this case, the combustion flame temperature is increased because it burns with high temperature preheated air.
Higher, thermal NOx increases. Also, the sky for combustion
To alternately switch between air supply and combustion exhaust gas emission
It is necessary to install a switching valve in the combustion air piping and the combustion exhaust gas piping.
It is necessary, and piping around the furnace becomes complicated.

Further, since the inner pipe fuel nozzle 17 and the outer pipe fuel nozzle 18 are arranged on the downstream side (front side) of the inner pipe heat storage body 13 and the outer pipe heat storage body 12, both the fuel gas and the combustion air are provided. Is difficult to be uniformly mixed, and particularly at low furnace temperature below the self-ignition temperature of the fuel gas, there are problems that ignition failure frequently occurs and stable combustion cannot be performed.

Therefore, the present invention provides a single-ended heat storage type radiant tube burner device capable of simultaneously achieving low NOx and energy saving and highly efficient combustion without damaging the combustion nozzle, and below the self-ignition temperature of fuel gas. It is an object of the present invention to provide a combustion method for a single-ended heat storage type radiant tube burner device capable of stable combustion even at low furnace temperature.

[0014]

In order to achieve the above-mentioned object, the present invention is a single-ended radiant consisting of an outer tube whose one end is closed and an inner tube arranged inside the outer tube with a predetermined interval. The outer tube annular space formed by the outer tube and the inner tube of the tube and the outer tube heat storage body and the inner tube heat storage body are housed in the inner tube, and the rear portions of the outer tube annular space and the inner tube are alternated. Is connected to two supply and discharge pipes communicating with the air supply source and the exhaust means, and the combustion in the combustion nozzles provided in the outer pipe annular space and the inner pipe is alternately switched at predetermined intervals to perform alternating combustion. In the single-ended heat storage type radiant tube burner device which alternately recovers the sensible heat of the combustion exhaust gas by the inner pipe heat storage body or the outer pipe heat storage body and burns with high temperature preheated air, the two supply / discharge pipes A Venturi type suction tube at the tip With this configuration, the supply / discharge pipe is communicated with a bypass pipe having an exhaust gas discharge port, and one of the two supply / discharge pipes is alternately used as an air supply means by switching a switching valve. With the configuration of communicating with each other, a plurality of the combustion nozzles are installed in the outer pipe annular space, a fuel gas is ejected from the central portion, and an outer pipe combustion nozzle of a double pipe structure that ejects cooling air from the outer periphery thereof, The inner pipe is arranged at the center of the inner pipe, and is composed of an inner pipe combustion nozzle of a double pipe structure that ejects fuel gas from the center and ejects cooling air from the outer periphery thereof, and the inner pipe heat storage body, It is mounted between the inner tube and the tip of the inner combustion nozzle, and the outer tube heat storage body is mounted between the outer tube and the tip of the outer combustion nozzle.

Further, a single-ended radiant tube of an outer pipe having one end closed and an inner pipe arranged inside the outer pipe at a predetermined interval is formed by the outer pipe and the inner pipe. An outer pipe heat storage body and an inner pipe heat storage body are built in the space and the inner pipe, and the respective rear portions of the outer pipe annular space and the inner pipe are alternately communicated with the air supply source and the exhaust means.
Connected to the supply and exhaust pipes of the book, the combustion in the outer pipe annular space and the combustion nozzle provided in the inner pipe is alternately switched at predetermined time intervals to perform alternating combustion, and the sensible heat of the combustion exhaust gas is stored in the inner pipe heat storage. In the combustion method of the single-end type heat storage type radiant tube burner device that alternately recovers the body or the outer tube heat storage body and burns with high temperature preheated air, when the furnace temperature is below the self-ignition temperature of the fuel gas, When the premixed fuel gas is supplied to either one of the outer tube annular space or the combustion nozzle provided in the inner tube to continue continuous combustion, and when the furnace temperature becomes equal to or higher than the self-ignition temperature of the fuel gas, the both combustion nozzles The alternating combustion is performed by switching the combustion at every predetermined time.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to FIG. The single-ended heat storage type radiant tube burner apparatus T according to the present invention is generally a single-ended radiant tube 20, an inner tube combustion nozzle 26, an outer tube combustion nozzle 30, and an inner tube heat storage element R.
₁ , an outer tube heat storage body R ₂ , a combustion air supply blower 40, and a fuel gas supply source 41.

The single-ended radiant tube 20 has an outer tube 21 whose front end (inside the furnace) is closed.
And an inner pipe 22 that is shorter than the outer pipe 21 and is disposed inside the outer pipe 21 at a predetermined interval.
The inside of the outer tube 21 communicates with the inside of the outer tube 21 at the tip of the outer tube. The rear ends of the outer pipe 21 and the inner pipe 22 are closed.

The inner tube combustion nozzle 26 has the inner tube 22
The inner pipe combustion chamber S ₁ is formed in the center of the first fuel supply pipe 27 at a predetermined distance from the rear end, and the first fuel supply pipe 27 for injecting the fuel gas to the center and the outer periphery thereof are arranged at a predetermined space. A first cooling air supply pipe 28, and the first fuel supply pipe 27 and the first cooling air supply pipe 28.
And a first cooling air supply passage 29 is formed between

The outer tube combustion nozzle 30 has the outer tube 21.
The outer tube 21 and the inner tube 22 are mounted in the annular space 23 formed by the inner tube 22 and the inner tube 22 at a predetermined distance from the rear end, and the outer tube combustion chamber S ₂ is formed in front of the outer tube 21 and the inner tube 22. It is composed of a second fuel supply pipe 31 for injecting a fuel gas into the inside and a second cooling air supply pipe 32 arranged on the outer periphery of the second fuel supply pipe 31 at a predetermined interval, and the second fuel supply pipe 31 and the second cooling air supply pipe 32. The second cooling air supply passage 33 is formed between the two.

An inner pipe heat storage body R ₁ is provided in the front part of the annular space formed between the inner pipe 22 and the first cooling air supply pipe 28, and the second cooling air supply of the annular space 23 is performed. Tube 3
The outer periphery of ₂ is loaded with the outer tube heat storage element R ₂ .

Further, a first supply / discharge pipe 24a and a second supply / discharge pipe 24b are provided at rear end portions of the outer pipe 21 and the inner pipe 22, and these first and second supply / discharge pipes 24a, 24a, The reference numeral 24b includes first and second Venturi type suction pipes 34a, 34b, respectively, and the venturi type suction pipes 34a, 34b are connected by a bypass pipe 35 having an exhaust gas discharge port 36.

The combustion air supply blower 40 includes a second Venturi type suction pipe 3 through an outer pipe combustion air switching valve V _1.
4b, and also via the inner tube combustion air switching valve V ₂
It is connected to the Venturi type suction pipe 34a and communicates with the mixer 42 and the second cooling air supply passage 33 provided in the air supply pipe to the first cooling air supply passage 29 through the control valve V ₃ .

The fuel gas supply source 41 communicates with a mixer 42 provided in an air supply pipe to the first cooling air supply passage 29 via a pressure reducing valve V ₄ and a temperature increasing solenoid valve V _6, and also has a pressure reducing valve. The inner pipe combustion fuel switching valve V ₇ to the first fuel supply pipe 27 via V ₅ , and the outer pipe combustion fuel switching valve V
₈ communicates with the second fuel supply pipe 31.

Next, the operation of the single-end heat storage type radiant tube burner device T having the above-mentioned structure will be described.

First, the outer pipe combustion air switching valve V ₁ is closed, the inner pipe combustion air switching valve V ₂ is opened, the control valve V ₃ is opened, the temperature raising solenoid valve V ₆ is opened, and the inner pipe combustion air switching valve V ₆ is opened. The fuel switching valve V ₇ and the outer pipe combustion fuel switching valve V ₈ are closed, and the combustion air supply blower 4 is closed.
The combustion air from 0 is supplied into the inner pipe 22 from the first supply / discharge pipe 24a through the first venturi-type suction pipe 34a, and the mixer 42 is provided in the first cooling air passage 29 of the inner pipe combustion nozzle 26. by being supplied with premixed premixed fuel gas, and ignited by igniting a pilot burner and a spark plug (not shown) provided on the inner tube combustion chamber S ₁ and the like, initiate combustion at an internal tube combustion chamber S ₁ To do.

The combustion exhaust gas generated by the combustion is inverted at the closed end of the outer pipe 21, and the inner pipe 22 and the outer pipe 2
1, the outer pipe heat storage body R ₂ is heated and discharged from the second supply / discharge pipe 24 b through the exhaust gas discharge port 36 provided in the bypass pipe 35. In this case, a part of the exhaust gas is sucked into the combustion air by the suction action of the combustion air ejected from the first Venturi type suction pipe 34a, which contributes to the reduction of NOx.

As described above, the combustion exhaust gas is the outer tube heat storage body R.
Although would also heat the outer tube combustion nozzle 30 with _2, the cooling air of a predetermined amount from the regulating valve V ₃ is supplied to the second cooling air supply pipe 32 of the outer tube combustion nozzle 30, Thermal cracking of the outer tube combustion nozzle 30 and cracking due to residual fuel are prevented.

The combustion by only the inner tube combustion nozzle 26 is continued until the temperature inside the furnace reaches a predetermined temperature, for example, the self-ignition temperature of the fuel gas or higher.

This is because when the fuel gas is supplied from the first fuel supply pipe 27 before the temperature inside the furnace reaches, for example, the self-ignition temperature of the fuel gas, the fuel gas will be about 10
This is because the combustion becomes unstable due to the fact that the jetting is performed at a high speed of 0 m / sec and the mixing with the combustion air is not sufficiently performed.

Therefore, when the temperature in the furnace reaches a predetermined temperature, the inner pipe combustion air switching valve V ₂ and the temperature increasing solenoid valve V _{6 are used.}
Are closed, the outer tube combustion air switching valve V ₁ and the outer tube combustion fuel switching valve V ₈ are opened, and the fuel gas adjusted to a predetermined pressure is supplied from the second fuel supply pipe 31, and 2 Kyuhaikan is supplied combustion air from 24 _b, which ignition combustion by the ignition means (not shown) provided on the outer tube the combustion chamber S _2. In this case, since the combustion air passes through the outer tube heat storage body R ₂ and is preheated during that time, stable combustion is immediately performed.

Then, the combustion exhaust gas is reversed at the closed end portion of the outer pipe 21, flows in the inner pipe 22, and flows into the inner pipe heat storage body R ₁
Is heated and discharged from the exhaust gas discharge port 36 through the first supply / discharge pipe 24a.

Also in this case, the inner pipe combustion nozzle 26 is heated by the high temperature combustion exhaust gas, but a predetermined amount of cooling air supplied from the control valve V _{3 is} supplied to the first cooling air supply passage 2
As a result, the inner tube combustion nozzle 26 is prevented from being thermally damaged and cracked due to residual fuel.

After a lapse of a predetermined time, for example, 10 seconds, the outer pipe combustion air switching valve V ₁ and the outer pipe combustion fuel switching valve V ₈ are closed, and the inner pipe combustion air switching valve V ₂ and the inner pipe combustion air switching valve V ₂ are closed. The fuel switching valve V ₇ is opened, and the combustion gas that is preheated with the fuel gas from the first fuel supply pipe 27 through the inner pipe heat storage body R ₁ is ejected to the inner pipe combustion chamber S ₁ and the ignition means (not shown) is provided. It ignites and burns stably. This combustion exhaust gas is heated through the outer pipe heat storage body R ₂ and then exhausted from the exhaust gas discharge port 36 through the second supply / discharge pipe 24b. In this case as well, the outer pipe combustion nozzle 30 is heated by the high temperature combustion exhaust gas, but since the second cooling air supply pipe 32 is supplied with a predetermined amount of cooling air from the control valve V ₃ , the outer pipe combustion nozzle 30 is heated. The thermal damage to the combustion nozzle 30 and the cracking due to the residual fuel are prevented.

After that, the above operation is repeated every predetermined time.

The fuel used is gaseous fuel.
If it is, it will not be specifically limited. Especially propane
When using high calorie gas such as gas or butane gas,
Improved burnability and alternate combustion during burner turndown
Unburned when switching (burning is switched to the other burner
There was a flame in one of the burners
The above-mentioned fuel is diluted with combustion air.
To lower the lower calorific value to H _L= 5000-10000 kca
l / m^ThreeIt is preferable to use a diluted fuel adjusted to N.

When the fuel gas and the combustion air are switched during alternating combustion, the switching valve is opened by opening the combustion air switching valve first and then opening the combustion fuel switching valve.
Needless to say, the closing operation is performed by first closing the combustion fuel switching valve and then closing the combustion air switching valve.

Further, in the above embodiment, the first and second
Venturi type suction pipes 34a, 3 for the supply / discharge pipes 24a, 24b
4b is provided, and a part of the combustion exhaust gas from the other supply / discharge pipe is sucked into the combustion air via the bypass pipe 35 by the momentum of ejection of the combustion air from one supply / discharge pipe from the Venturi type suction pipe, Although the NOx is reduced by circulating the exhaust gas, it goes without saying that another configuration may be used to reduce the NOx. However, with the above configuration, it is not necessary to provide an exhaust gas circulation pipe or an exhaust gas switching valve on the suction side of the combustion air supply blower 40, and a simple and inexpensive facility can be provided.

Further, in the above embodiment, when the temperature in the furnace is lower than the self-ignition temperature of the fuel gas, the inner tube combustion nozzle 2
Although the premixed fuel gas is supplied from the first cooling air supply passage 29 of No. 6 and burned, the premixed fuel gas may be supplied from the first fuel supply pipe 27.

Further, the premixed fuel gas may be supplied from the second cooling air supply passage 33 of the outer pipe combustion nozzle 30 or the second fuel supply pipe 31.

[0040]

As is apparent from the above description, claim 1
According to the invention, the combustion method is alternating combustion, the combustion exhaust gas alternately passes through the heat storage body provided in the inner pipe and the space between the inner pipe and the outer pipe, and the combustion air is the heat storage heated in the previous step. Since it is preheated through the body, the heat recovery efficiency is 80-50%
It is also possible to perform combustion with high energy efficiency and high thermal efficiency. Moreover, the combustion nozzle provided in the inner pipe and the annular space between the inner pipe and the outer pipe has a double-pipe structure in which the fuel gas is ejected from the central portion and the cooling air is ejected from the outer periphery thereof, so that the combustion nozzle is a combustion exhaust gas. Therefore, it is not burnt out thermally.

Further, since the two supply / discharge pipes are provided with a venturi type suction pipe, and the venturi type suction pipe portion is connected by a bypass pipe having an exhaust gas discharge port, a part of the combustion exhaust gas is venturied. Since it is sucked and supplied by the combustion air ejected from the die suction pipe (self-exhaust gas circulation),
No exhaust gas switching valve is required, and no exhaust gas circulation pipe is required on the suction side of the combustion air supply blower, so NOx can be reduced with a simple configuration.

According to the second aspect of the present invention, when the temperature in the furnace is equal to or lower than the self-ignition temperature of the fuel gas, the premixed fuel gas is supplied to either the outer tube annular space or the combustion nozzle provided in the inner tube. Since continuous combustion is performed, stable combustion can be performed even at low furnace temperature.

[Brief description of drawings]

FIG. 1 is a schematic view of a single-end heat storage type radiant tube burner device according to the present invention.

FIG. 2 is a schematic view of a conventional single-ended radiant tube burner.

FIG. 3 is a schematic view of a conventional single-ended heat storage type radiant tube burner.

[Explanation of symbols]

20 ~ single end radiant tube, 21 ~ outer
Pipe, 22 to inner pipe, 23 to annular space, 24a, 24b to supply
Exhaust pipe, 26-inner pipe combustion nozzle, 27-first fuel supply pipe,
28-first cooling air supply pipe, 31-second fuel supply pipe, 3
2nd-2nd cooling air supply pipe, 34a, 34b-Venturi
Mold suction pipe, 35-bypass pipe, 36-exhaust gas discharge port, 4
0-air supply source, 41-fuel gas supply source, 42-mixer
ー 、 R₁~ Inner tube heat storage, R_Two~ Outer tube heat storage, T ~ Thing
Ruend type heat storage type radiant tube burner device, V₁
~ Outer tube combustion air switching valve, V_Two~ Air switching for inner tube combustion
Valve, V _Three~ Control valve, V₆~ Solenoid valve for heating.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3K017 BA01 BA02 BA06 BB04 BB05                       BB07 BE11 DC03 DC04                 3K023 QA16 QB02 QC07                 3K091 AA01 AA18 BB08 BB26 CC06                       CC22 EA04 EA16                 4K056 BB02 DA02 DA27 DA32

Claims (2)

[Claims] 1. An outer tube ring formed by the outer tube and the inner tube of a single-ended radiant tube having an outer tube whose one end is closed and an inner tube arranged inside the outer tube with a predetermined interval. Two supply / exhaust units are provided in which the outer pipe heat storage body and the inner pipe heat storage body are built in the space and the inner pipe, and the rear portions of the outer pipe annular space and the inner pipe are alternately communicated with the air supply source and the exhaust means. Combustion in a combustion nozzle provided in the outer pipe annular space and the inner pipe is alternately switched at predetermined intervals to perform alternating combustion, and the sensible heat of the combustion exhaust gas is transferred to the inner pipe heat storage body or the outer pipe. In a single-end type heat storage type radiant tube burner device which alternately collects heat by a heat storage body and burns with high-temperature preheated air, the two supply / discharge pipes are provided with a Venturi type suction pipe at the tip, Supply and exhaust pipe with exhaust gas outlet A communication is made with an IPASS pipe, and one of the two supply / discharge pipes is alternately connected to the air supply means by switching the switching valve, and the combustion nozzle is connected to the outer pipe ring. Multiple outer pipe combustion nozzles that are installed in the space, eject fuel gas from the center and eject cooling air from the outer periphery, and are arranged in the center of the inner pipe, and the fuel gas is ejected from the center. And an inner tube combustion nozzle with a double tube structure that ejects cooling air from its outer periphery,
The inner pipe heat storage body is mounted between the inner pipe and the tip portion of the inner pipe combustion nozzle, and the outer pipe heat storage body is mounted between the outer pipe and the tip portion of the outer pipe combustion nozzle. A single-ended heat storage type radiant tube burner device characterized by the above. 2. An outer tube ring formed by the outer tube and the inner tube, which is a single-ended radiant tube having an outer tube whose one end is closed and an inner tube arranged inside the outer tube with a predetermined interval. Two supply / exhaust units are provided in which the outer pipe heat storage body and the inner pipe heat storage body are built in the space and the inner pipe, and the rear portions of the outer pipe annular space and the inner pipe are alternately communicated with the air supply source and the exhaust means. Combustion in a combustion nozzle provided in the outer pipe annular space and the inner pipe is alternately switched at predetermined intervals to perform alternating combustion, and the sensible heat of the combustion exhaust gas is transferred to the inner pipe heat storage body or the outer pipe. In the combustion method of a single-ended heat storage type radiant tube burner device in which heat is alternately collected by a heat storage body and burned with high-temperature preheated air, when the temperature inside the furnace is below the self-ignition temperature of the fuel gas, the outer ring Fuel provided in space or inner pipe Supplies premixed fuel gas continues to continuous combustion to either one of the nozzles,
A combustion method for a single-end heat storage type radiant tube burner device, characterized in that, when the temperature in the furnace becomes equal to or higher than the self-ignition temperature of the fuel gas, the combustion in both combustion nozzles is switched at predetermined intervals to perform alternating combustion.