JP2009204285A - Burner and its operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a burner for performing stable high temperature air combustion using high temperature low oxygen air discharged from a solid oxide fuel cell device as an oxidizer and its operation method. <P>SOLUTION: This burner includes a gas gun 2 disposed in the central part and an air feed pipe group 3 disposed in the outer peripheral part of the gas gun, wherein the gas gun 2 includes a fuel feed pipe 21 for feeding gas fuel and a pilot air feed pipe 22 disposed coaxially with the outer peripheral part thereof to feed fresh pilot air, and the air feed pipe group 3 includes a plurality of air feed pipes 31 for feeding fresh air and a plurality of combustion exhaust gas feed pipes 32 for feeding high temperature low oxygen air. In this burner, these two kinds of feed pipes are alternately disposed on the circumference, and an exhaust nozzle of the gas gun is located at the inner side of the burner more than the exhaust nozzle of the air feed pipe group. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a burner used as a heating means for a heating furnace, a boiler, a combustion furnace, a drying furnace, a hot air furnace, a chemical reaction furnace, etc., and an operating method thereof. The present invention relates to a burner that uses high-temperature, low-oxygen-concentrated air (hereinafter, sometimes referred to as high-temperature, low-oxygen air) as an oxidizing agent to burn high-temperature air.

High-temperature air combustion uses high-temperature, low-oxygen air as an oxidant and burns at a high temperature of 800 ° C. or higher. The amount of nitrogen oxide (NOx) generated is small, the heat transfer effect is high, and the temperature is low and low. It is said that there is an advantage that the heat of oxygen air can be effectively recovered and used.
As burners for this high-temperature air combustion, for example, burners disclosed in Japanese Patent Application Laid-Open Nos. 7-248103 and 9-133324 are known.

However, in the burners in these prior inventions, in order to perform stable high-temperature air combustion, fresh air is mixed with high-temperature low-oxygen air to adjust the oxygen concentration, so the oxygen concentration in the supply air Is insufficient, and nitrogen oxide is insufficiently reduced. Further, since fresh air is mixed, there is a problem that the heat of the high-temperature low-oxygen air cannot be sufficiently recovered.
In addition, since high temperature and low oxygen air is mixed, it is necessary to prevent the components of the burner from being deformed due to high temperature. Therefore, an expensive material is required, or a structure for mixing fresh air with high temperature and low oxygen air is required. It is complicated. Furthermore, since ignition is often performed by using an igniter rod or the like and sparking in the vicinity of the nozzle tip of the burner, there has been a limit to downsizing.
Japanese Patent Laid-Open No. 7-248103 JP-A-9-133324

  Therefore, the problem in the present invention is that stable high-temperature air combustion can be performed even in low-oxygen air, and the generation amount of nitrogen oxides is small, and the heat of high-temperature low-oxygen air can be sufficiently recovered, leading to fuel reduction. It is to obtain a burner that can be installed in a space-saving manner and an operation method thereof.

To solve this problem,
The invention according to claim 1 is a burner for performing high-temperature air combustion,
It has a gas gun arranged in the center and an air supply pipe group arranged on the outer periphery of this gas gun,
The gas gun includes a fuel supply pipe that supplies gaseous fuel, a pilot air supply pipe that is coaxially arranged on an outer periphery of the gas gun and supplies fresh pilot air, and a tip portion of the fuel supply pipe. A main fuel injection nozzle and a sub fuel injection hole formed, the main fuel injection nozzle is disposed on the central axis of the fuel supply pipe, a plurality of sub fuel injection holes are formed on the side of the fuel supply pipe,
The air supply pipe group is composed of a plurality of air supply pipes for supplying fresh air and a plurality of combustion exhaust gas supply pipes for supplying high-temperature low-oxygen air. These two types of supply pipes are circular. It is arranged alternately on the circumference,
The burner is characterized in that a jet port of the gas gun is located on an inner side of the burner than a jet port of the air supply pipe group.

  According to a second aspect of the present invention, a central hole is drilled along the central axis of a cylindrical body made of a refractory material, a plurality of peripheral holes are drilled circumferentially around the central hole, and the gas gun is disposed in the central hole. The burner according to claim 1, characterized in that the air supply pipe and the combustion exhaust gas supply pipe are alternately accommodated in the surrounding holes.

The invention according to claim 3 is the method of operating the burner according to claim 1 or 2,
At the start of combustion, gas fuel is supplied to the fuel supply pipe of the gas gun, fresh air is supplied to the pilot air supply pipe, and fresh air is supplied to the air supply pipe of the air supply pipe group to start ignition and combustion. Then, gradually increase the supply of gaseous fuel and fresh air,
When the combustion temperature exceeds 700 ° C, the amount of fresh air supplied to the air supply pipe is reduced and high-temperature low-oxygen air starts to be supplied to the combustion exhaust gas supply pipe, and then the supply of fresh air is stopped. The operation method of the burner is characterized by shifting to stable high-temperature air combustion.

The invention according to claim 4 is the burner operating method according to claim 3, wherein the high-temperature low-oxygen air is air having a temperature of 350 to 800 ° C. and an oxygen concentration of 6 to 21% by volume.
The invention according to claim 5 is the burner operating method according to claim 3 or 4, wherein the high-temperature low-oxygen air is exhaust gas from a solid oxide fuel cell device.

According to the present invention, the thermal energy of high-temperature low-oxygen air discharged as exhaust gas from a solid oxide fuel cell device or the like is converted into the heat output of the burner and effectively recovered, and the fuel consumption is reduced. In addition, nitrogen oxides in the exhaust gas discharged from the burner are also reduced.
Furthermore, since fresh air with a high oxygen concentration is used as the oxidant at the start of combustion of the burner, ignition is reliably performed and combustion is started in a stable combustion state. Thereby, the introduction of the high-temperature low-oxygen air into the burner is smoothly performed, and it is possible to smoothly shift to the high-temperature air combustion state, and this high-temperature air combustion state can be stably maintained.
Moreover, when a predetermined air-fuel ratio cannot be ensured only with high-temperature low-oxygen air, the high-temperature air combustion state can be stably maintained by using a mixed gas of high-temperature low-oxygen air and fresh air.

1 to 4 show an example of the burner of the present invention.
As shown in FIG. 1, the burner in this example includes a body 1 made of a refractory material, a gas gun 2 housed in the body 1, and a group of air supply pipes housed inside the body 1 and outside the gas gun 2. 3.

  The body 1 is a cylindrical body made of a refractory material such as a calcium silicate molded body, and is formed with one central hole extending in the longitudinal direction along the central axis, outside the central hole, In addition, eight peripheral holes extending in parallel with the central hole are perforated.

As shown in FIGS. 1 and 2, a gas gun 2 is accommodated in the center hole of the body 1, and four air supply pipes 31... The air supply pipe group 3 is configured by alternately storing the supply pipes 32.
As shown in FIG. 1, the opening tip of each feed pipe forming the air feed pipe group 3 is substantially the same position as the opening tip of the body 1, and the opening tip of the gas gun 2 is the center. It is located on the inner side (rear side of the burner) than the opening tip of the hole.
Between the opening tip of the gas gun 2 and the opening tip of the center hole of the body 1, the opening diameter of the center hole gradually increases toward the opening tip to form a substantially conical space.

A body cover 8 is provided on the rear side of the body 1 so as to surround the body 1, and a metal pipe 5 is provided behind the body cover 8. The metal pipe 5 is connected to a fresh air introduction pipe 6 for introducing fresh air and a combustion exhaust gas introduction pipe 7 for introducing high-temperature low-oxygen air.
The fresh air introduction pipe 6 communicates with the four air supply pipes 31 through a manifold (not shown) in the body 1, and the combustion exhaust gas introduction pipe 7 passes through a manifold (not shown) in the body 1. Are communicated with four combustion exhaust gas supply pipes 32.

  As a result, the fresh air introduced from the fresh air introduction pipe 6 flows into the four air supply pipes 31..., Is ejected from the tip of the opening, and is introduced from the combustion exhaust gas introduction pipe 7. Flows into the four combustion exhaust gas supply pipes 32... And is ejected from the tip of the opening.

FIG. 3 shows the gas gun 2. The gas gun 2 has a dual structure comprising a fuel feed pipe 21 that feeds gaseous fuel and a pilot air feed pipe 22 that is coaxially arranged outside the fuel feed pipe 21 and feeds fresh pilot air. It has a tube structure. The fuel supply pipe 21 and the pilot air supply pipe 22 are electrically insulated.
As shown in FIG. 1, most of the front part of the gas gun 2 is housed in the body 1 as described above, but the rear part protrudes from the body 1 and extends rearward to be exposed. is doing.

  The distal end portion of the fuel supply pipe 21 is a cylindrical main fuel injection nozzle 23 whose inner diameter is reduced, and is configured so that most of the gaseous fuel is ejected forward from the main fuel injection nozzle 23. Has been. A plurality of auxiliary fuel injection holes 28 are formed in the side wall portion of the fuel supply pipe 21 slightly behind the main fuel injection nozzle 23 so as to penetrate therethrough. These auxiliary fuel injection holes 28 are formed at asymmetric positions with respect to the outer peripheral wall of the fuel supply pipe 21, and a small amount of gaseous fuel is widened toward the side of the fuel supply pipe 21. It is configured to be dispersed and ejected.

Also, the tip of the main fuel injection nozzle 23 is positioned in front of the tip of the pilot air supply pipe 22, and the tip of the pilot air supply pipe 22 is positioned behind the auxiliary fuel injection holes 28. It has become.
Further, the rear end portion 21 of the fuel supply pipe is communicated with a fuel introduction port 24 for introducing gaseous fuel.

  As shown in FIG. 4, a plurality of jet holes 25... Arranged in a circumferential manner are formed at the tip of the pilot air supply pipe 22. Pilot air is jetted out. A rear portion of the pilot air supply pipe 22 communicates with a pilot air inlet (not shown in FIG. 3).

  A spark plug 27 is attached to the rear projecting portion of the gas gun 2, one electrode of the spark plug 27 is electrically connected to the fuel feed pipe 21, and the other electrode is connected to the pilot air feed. It is electrically connected to the supply pipe 22, and is configured such that discharge is performed between the ejection nozzle 23 and the vicinity of the tip of the pilot air supply pipe 22.

  An ignition transformer (not shown) is connected to the ignition plug 27, and by applying a high-voltage current from the ignition transformer to the ignition plug 27, discharge is performed near the tip opening of the gas gun 2 so that ignition is performed. It has become.

  In such a burner, a part of the gaseous fuel is ejected from the auxiliary fuel ejection holes 28 of the fuel feed pipe 21 of the gas gun 2 and mixed with fresh air flowing through the pilot air feed pipe 22. Primary combustion takes place. At this time, since the auxiliary fuel injection holes 28 are asymmetrically provided, the mixing with the fresh air becomes non-uniform and ignition is possible in a wide range.

  The remaining part of the gaseous fuel is jetted forward from the main fuel jet nozzle 23 and flows into the pilot air feed pipe 22 and the air feed pipe 31 of the air feed pipe group 3... Fresh air or combustion exhaust gas feed pipe 32 .. Secondary combustion by mixing with high-temperature, low-oxygen air flowing through.

  Since the air feed pipes 31 and the combustion exhaust gas feed pipes 32 forming the air feed pipe group 3 are alternately arranged on the circumference, the air feed pipes 31 and / or the combustion exhaust gas feed pipes 32 are arranged. .. The flow of fresh air or high-temperature low-oxygen air ejected from the air uniformly surrounds the flow of gaseous fuel ejected from the main fuel injection nozzle 23, and the mixing of the two becomes good. Even so, secondary combustion is performed well.

  For this reason, even when only fresh air is supplied or when fresh air and high-temperature low-oxygen air are supplied, stable combustion is performed. When the combustion temperature reaches 700 ° C. or higher, only high-temperature low-oxygen air is supplied. Even if supplied, stable high-temperature air combustion is performed, and smooth transition to high-temperature air combustion becomes possible.

Next, a method for operating such a burner will be described with reference to an example in which this burner is installed in a combustion furnace.
FIG. 5 shows an example of a timing chart showing the supply timing of gaseous fuel, fresh air, high-temperature low-oxygen air, etc. at the start of burner operation.

First, when starting the burner at time t ₀ , gaseous fuel is supplied to the fuel supply pipe 21 of the gas gun 2, and the pilot air supply pipe 22 of the gas gun 2 and the air supply pipe of the air supply pipe group 3 are supplied. Supply fresh air to 31 ... The air flow rate to the air feed pipes 31 is made larger than the air flow rate to the pilot air feed pipe 22.
The ignition plug 27 is operated to ignite near the tip opening of the gas gun 2 and start combustion.
This state is maintained for a while and the temperature in the furnace is gradually raised.

Then, at time t _1, and increasing the supply flow rate of the gaseous fuel to the fuel feed pipe 21, to increase the fresh air supply flow rate to the air supply pipe 31 .. Accordingly, the continue combustion Then, raise the temperature in the furnace.
When the combustion temperature is a time t ₂ exceeding 700 ° C., with gradually reduced the supply flow rate of fresh air into the air supply pipe 31 ..., the supply of high temperature and low oxygen air in the combustion exhaust gas feed pipe 32 .. Start and gradually increase its supply flow rate. During this time, the furnace temperature continues to rise.

At time t _3, the supply flow rate to the flue gas feed pipe 32 ... of high temperature and low oxygen air is constant, to stop the supply of fresh air to the air supply pipe 31 .... The supply of fresh air to the pilot air supply pipe 22 continues. During this time, the furnace temperature continues to rise and approaches 800 ° C. where high-temperature air combustion is possible.

At time t _4, the furnace temperature becomes 800 ° C. or higher, lose weight the supply amount to the fuel feed pipe 21 of the gas fuel. The time t ₄ later, the oxidizing agent becomes only high temperature and low oxygen air, stable high-temperature air combustion state is maintained.

As the gaseous fuel, liquefied natural gas (LNG), liquefied petroleum gas (LPG), propane, butane, or the like is used.
Here, fresh air refers to air in the atmosphere having a normal oxygen concentration of 21% by volume and a temperature of 5 to 50 ° C., and is a term for distinguishing from high-temperature low-oxygen air.
High temperature low oxygen air refers to air having a temperature of 350 to 550 ° C. and an oxygen concentration of 6 to 21% by volume, such as exhaust gas discharged from various combustion furnaces, solid oxide fuel cells, solid oxide fuel cell devices, and the like. This is the case.

The solid oxide fuel cell device here refers to a well-known solid oxide fuel cell to which a thermal device such as a combustion furnace or a heat exchanger is attached, and the exhaust gas from the solid oxide fuel cell is further heated. Exhaust gas that is secondarily discharged from these thermal devices after being used in the devices is also included in the high-temperature low-oxygen air of the present invention.
The combustion temperature refers to the temperature in the furnace measured at a position 30 cm away from the front end surface of the burner and 10 cm away from the outer peripheral wall surface of the burner.

The total amount of fresh air flow supplied to the burner and high-temperature low-oxygen air is assumed to contain oxygen sufficient for complete combustion of the gaseous fuel supplied simultaneously, and is about 1.1 times the theoretical air volume. To be adjusted.
Then, the combustion state at time t ₄ after is in a state of high-temperature air combustion, high heat transfer effect, a state of generation was also suppressed nitrogen oxides. What is necessary is just to continue the combustion of a burner for the required time, maintaining the state of this high temperature air combustion.
When the combustion of the burner is stopped, the supply of gaseous fuel to the fuel feed pipe 21 of the gas gun 2 is stopped, and the supply of high-temperature low oxygen air to the combustion exhaust gas feed pipe 32.

  By adopting such an operation method, it is possible to smoothly shift to high-temperature air combustion using high-temperature and low-oxygen air, and to realize stable high-temperature air combustion. Moreover, it can utilize for the heat output of a burner, without losing the thermal energy which high temperature low oxygen air has, it becomes possible to reduce the consumption of gaseous fuel, and the thermal efficiency of the whole system becomes high.

It is the side view seen from the partial cross section which shows an example of the burner of this invention. It is drawing which shows the opening front-end | tip part of the burner shown in FIG. It is the side view which carried out the partial cross section which shows an example of the gas gun in the burner of this invention. It is drawing which shows the opening front-end | tip part of the gas gun shown in FIG. It is a timing chart which shows an example of the driving | running method of this invention.

Explanation of symbols

1 .... Body, 2 .... Gas gun, 3 .... Air supply pipe group, 21 ... Fuel supply pipe, 22 .... Pilot air supply pipe, 31 ... Air supply pipe, 32 ... Fusion exhaust gas supply Feed pipe, 23 ... Main fuel injection nozzle, 28 ... Sub fuel injection hole

Claims (5)

A burner for performing hot air combustion,
It has a gas gun arranged in the center and an air supply pipe group arranged on the outer periphery of this gas gun,
The gas gun includes a fuel supply pipe that supplies gaseous fuel, a pilot air supply pipe that is coaxially arranged on an outer periphery of the gas gun and supplies fresh pilot air, and a tip portion of the fuel supply pipe. A main fuel injection nozzle and a sub fuel injection hole formed, the main fuel injection nozzle is disposed on the central axis of the fuel supply pipe, a plurality of sub fuel injection holes are formed on the side of the fuel supply pipe,
The air supply pipe group is composed of a plurality of air supply pipes for supplying fresh air and a plurality of combustion exhaust gas supply pipes for supplying high-temperature low-oxygen air. These two types of supply pipes are circular. It is arranged alternately on the circumference,
The burner characterized in that the jet port of the gas gun is located on the inner side of the burner than the jet port of the air supply pipe group.   A central hole is drilled along the central axis of the cylindrical body made of a refractory material, a plurality of peripheral holes are drilled around the central hole, the gas gun is accommodated in the central hole, and the air is fed to the peripheral hole. The burner according to claim 1, wherein a supply pipe and the combustion exhaust gas supply pipe are alternately accommodated. A method of operating a burner according to claim 1 or 2,
At the start of combustion, gas fuel is supplied to the fuel supply pipe of the gas gun, fresh air is supplied to the pilot air supply pipe, and fresh air is supplied to the air supply pipe of the air supply pipe group to start ignition and combustion. Then, gradually increase the supply of gaseous fuel and fresh air,
When the combustion temperature exceeds 700 ° C, the amount of fresh air supplied to the air supply pipe is reduced and high-temperature low-oxygen air starts to be supplied to the combustion exhaust gas supply pipe, and then the supply of fresh air is stopped. Then, the method of operating the burner is characterized by shifting to stable high-temperature air combustion.   The burner operating method according to claim 3, wherein the high-temperature low-oxygen air is air having a temperature of 350 to 550 ° C and an oxygen concentration of 6 to 21% by volume.   The burner operating method according to claim 3 or 4, wherein the high-temperature low-oxygen air is exhaust gas from a solid oxide fuel cell device.

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