JP6904293B2 - Burner and heating method - Google Patents

Description

The present invention relates to a burner, and more particularly to a burner capable of forming a flame jet having a higher temperature and a higher speed than the conventional one and having an extremely high heating power. The present invention also relates to a heating method using the burner.

There are various types of burners used for heating articles, and among them, a high-speed burner is used as a burner capable of forming a high-temperature and high-speed gas flow.

The high-speed burner forms a high-speed gas flow (jet flow) by discharging high-temperature exhaust gas generated by burning fuel gas in a combustion chamber from a nozzle (for example, Patent Document 1). In the high-speed burner, the speed of the high-speed gas flow can be increased to the sonic region by increasing the pressure in the combustion chamber.

Japanese Patent No. 5967783

However, the conventional high-speed burner has the following problems.

Attempts to obtain a hotter, faster gas stream to increase heating efficiency will expose the combustion chambers and nozzles to extremely high temperatures. In order to manufacture a high-speed burner having heat resistance capable of withstanding such a high temperature, particularly an ultra-high temperature exceeding 1200 ° C., it is necessary to use a very expensive refractory or the like, so that it is cost effective. There was a problem.

Further, if an attempt is made to further increase the discharge speed of the high-speed gas flow, there is also a problem that the temperature of the high-speed gas flow drops due to adiabatic expansion after discharge.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a burner capable of forming a flame jet having a higher temperature and a higher speed than the conventional one and having an extremely high heating power. Another object of the present invention is to provide a heating method using the burner.

The gist structure of the present invention is as follows.

1. 1. A fuel gas nozzle that discharges fuel gas and
An air nozzle that discharges combustion air and
A burner including a high-temperature gas nozzle that discharges a high-temperature gas for igniting the fuel gas.

2. The burner according to 1 above, wherein the fuel gas nozzle and the air nozzle are Laval nozzles.

3. 3. The burner according to 1 or 2 above, wherein the high temperature gas is combustion exhaust gas.

4. Further, a burner for generating high temperature gas for generating the high temperature gas and a burner for generating high temperature gas,
3. The burner according to 3 above, comprising a combustion chamber to which the high temperature gas generating burner is connected.

5. Further, a temperature adjusting air supply unit that supplies temperature adjusting air to the combustion chamber, and a temperature adjusting air supply unit,
4. The burner according to 4 above, comprising a temperature measuring means for measuring the temperature in the combustion chamber.

6. 4. The burner according to 4 or 5, wherein a combustion air chamber for cooling the combustion chamber and preheating the combustion air is provided outside the combustion chamber.

7. The burner according to 6 above, wherein a fuel gas chamber for preheating the fuel gas is provided outside the combustion air chamber.

8. The heating method using the burner according to any one of 1 to 7 above.
A heating method in which the temperature of the high temperature gas is 800 ° C. or higher.

9. The heating method using the burner according to 5 above.
The temperature of the high temperature gas is controlled to 800 ° C. or higher and 1000 ° C. or lower by controlling the supply amount of the temperature adjusting air supplied from the temperature adjusting air supply unit based on the temperature measured by the temperature measuring means. How to heat.

10. The heating method according to 9 above.
A heating method in which the ratio of the amount of high-temperature gas-producing fuel gas supplied to the high-temperature gas-generating burner to the amount of the fuel gas supplied to the fuel-gas nozzle is 10 to 30%.

11. The heating method according to 9 above.
A heating method in which when the temperature measured by the temperature measuring means becomes 780 ° C. or lower, nitrogen purging is performed on the fuel gas nozzle and the pipe for supplying fuel gas to the high temperature gas generation burner to shut off combustion.

12. 8. The heating method according to 8 or 9, wherein the discharge speed of the high temperature gas discharged from the high temperature gas nozzle is 100 m / s or more.

13. The discharge speed of the fuel gas discharged from the fuel gas nozzle is 50 Nm / s or more.
The heating method according to any one of 8 to 12 above, wherein the discharge speed of the combustion air discharged from the air nozzle is 50 Nm / s or more.

14. The discharge speed of the fuel gas discharged from the fuel gas nozzle is equal to or higher than the speed of sound.
13. The heating method according to 13 above, wherein the discharge speed of the combustion air discharged from the air nozzle is equal to or higher than the speed of sound.

15. The amount of the combustion air discharged from the air nozzle is controlled according to the amount of the fuel gas discharged from the fuel gas nozzle so that the air ratio is 0.7 to 1.5. The heating method according to any one of ~ 14.

According to the present invention, a flame jet having a higher temperature and a higher speed than the conventional one can be formed, and heating can be performed with extremely high efficiency. In particular, in the burner of the present invention, since the high temperature gas discharged from the high temperature gas nozzle is used to ignite the fuel gas discharged from the fuel gas nozzle, it is not necessary to form the high temperature gas in the combustion chamber as in the conventional high speed burner. .. Therefore, the generated flame temperature can be raised without being restricted by the material and structure of the burner, and an ultra-high temperature and high-speed flame jet such as 1500 ° C. or higher can be formed.

It is a schematic diagram which shows the structure of the burner in one Embodiment of this invention. It is a schematic diagram which shows the combustion state in one Embodiment of this invention.

Next, the method of carrying out the present invention will be specifically described. The following description shows a preferred embodiment of the present invention, and the present invention is not limited to the following description.

[Burner]
FIG. 1 is a schematic view showing the structure of the burner 1 according to the embodiment of the present invention. The burner 1 includes a fuel gas nozzle 10 that discharges fuel gas at its tip, and an air nozzle 20 that discharges combustion air.

[Fuel gas nozzle, air nozzle]
The fuel gas is supplied from the fuel gas supply unit 11 as indicated by the arrow G1, passes through the fuel gas chamber 12, and is discharged from the fuel gas nozzle 10. Similarly, the combustion air is supplied from the combustion air supply unit 21 as indicated by the arrow A1, is discharged from the air nozzle 20 through the combustion air chamber 22.

The fuel gas nozzle 10 and the air nozzle 20 can be nozzles of any shape, and can be, for example, straight pipe nozzles. However, from the viewpoint of increasing the speed of the flame, it is preferable that the fuel gas nozzle 10 and the air nozzle 20 are Laval nozzles as in the embodiment shown in FIG. The Laval nozzle is a nozzle having a reduced diameter portion in the middle portion in the longitudinal direction of the nozzle as shown in FIG. By using the Laval nozzle, the discharge speed of the fuel gas and the combustion air can be set to a high speed such as, for example, the speed of sound or higher, and as a result, a high-speed flame jet can be formed.

The amount of heat transferred from the flame to the surface of the object to be heated is proportional to the heat transfer coefficient, and the heat transfer coefficient α increases as the speed of the flame increases. Therefore, by colliding the flame jet with the surface of the object to be heated at high speed, heating can be performed with extremely high efficiency. As a result, the object to be heated can be heated to a higher temperature at a higher speed. Also, by increasing the speed of the flame, the amount of fuel gas required to achieve the same heating temperature can be reduced. In order to increase the discharge rate while reducing the amount of fuel gas used, the nozzle cross-sectional area may be reduced.

[High temperature gas nozzle]
The burner 1 includes a high-temperature gas nozzle 30 that discharges a high-temperature gas for igniting the fuel gas. In the embodiment shown in FIG. 1, the burner 1 further includes a combustion chamber 40 connected to the high temperature gas nozzle 30 and a high temperature gas generation burner 50 connected to the combustion chamber. As shown in FIG. 1, the wall surface of the combustion chamber 40 is preferably a heat insulating wall 41 made of a heat insulating material having an iron skin structure on the outside. The combustion chamber 40 may be provided with a pilot burner 54 that is ignited by an igniter such as a spark plug.

The material of the high temperature gas nozzle 30 is not particularly limited, and any material such as metal or ceramic can be used. However, from the viewpoint of heat resistance, it is preferable to use a heat-resistant casting, a heat-resistant metal such as SUS310S, or a ceramic such as SiC.

Fuel gas is supplied to the high temperature gas generation burner 50 as shown by an arrow G2, and the fuel gas is discharged from the high temperature gas generation fuel gas nozzle 51. Further, combustion air is supplied to the high temperature gas generation burner 50 as shown by an arrow A2, and the combustion air is discharged from the high temperature gas generation air nozzle 52. It is desirable to install a swirl vane 53 inside the air nozzle 52 for generating high temperature gas to promote mixing of fuel gas and fuel air and stabilize combustion. The high temperature gas generation burner 50 is ignited by the pilot burner 54 or directly by an igniter (not shown).

FIG. 2 is a schematic view showing a combustion state in one embodiment of the present invention. The fuel gas discharged from the high-temperature gas generation burner 50 is ignited, and a flame 55 is formed in the combustion chamber 40. As a result, high-temperature gas (combustion exhaust gas) is generated in the combustion chamber 40, and the high-temperature gas is discharged from the high-temperature gas nozzle 30 to form a high-temperature gas flow 35.

As described above, the fuel gas is discharged from the fuel gas nozzle 10 to form the fuel gas flow 15, and the combustion air is discharged from the air nozzle 20 to form the combustion air flow 25. Therefore, the fuel gas flow 15 is ignited by the high temperature gas flow 35 discharged from the high temperature gas nozzle 30, and the high-speed jet flame 60 is formed.

In the embodiment shown in FIG. 1, the burner 1 includes a combustion chamber 40 and a burner 50 for generating high-temperature gas, and generates high-temperature gas in the combustion chamber 40. However, the burner 1 generates high-temperature gas. It can also be done outside of. In that case, for example, a high-temperature gas generator provided outside the burner 1 may generate high-temperature gas, and the obtained high-temperature gas may be sent to the high-temperature gas nozzle 30 of the burner 1 through a pipe or the like.

[Air supply unit for temperature control]
The burner 1 preferably includes a temperature adjusting air supply unit 70 that supplies temperature adjusting air into the combustion chamber 40. If the inside of the combustion chamber 40 rises excessively, deterioration of the material of the burner 1 due to high temperature may become a problem. Therefore, the temperature of the high temperature gas can be adjusted to an appropriate range by diluting the high temperature gas in the combustion chamber with the temperature adjusting air.

[Temperature measuring means]
It is preferable that the burner 1 further includes a temperature measuring means 71 for measuring the temperature in the combustion chamber. By using the temperature measuring means 71, the temperature in the combustion chamber 40 described above can be easily controlled. Specifically, it is preferable to control the supply amount of the temperature adjusting air based on the temperature measured by the temperature measuring means 71 as described later. As the temperature measuring means 71, for example, a thermocouple or the like can be used.

[Preheating]
As shown in FIG. 1, the combustion air chamber 22 is preferably provided outside the combustion chamber 40. By providing the combustion air chamber 22 adjacent to the combustion chamber 40 in this way, the combustion air can be preheated by the heat of the combustion chamber, and at the same time, the combustion chamber can be cooled by the combustion air.

Further, as shown in FIG. 1, the fuel gas chamber 12 is preferably provided outside the combustion air chamber 22. By providing the fuel gas chamber 12 adjacent to the combustion air chamber 22 in this way, the fuel gas can be preheated and the combustibility can be improved.

[Fuel gas]
The fuel gas is not particularly limited, and any flammable gas can be used. For example, natural gas or LPG can be generally used, and when the burner is used in a steelworks, a process gas produced as a by-product in the steelworks can also be used as the fuel gas. As the process gas, it is particularly preferable to use M gas, which is a mixture of coke oven gas and blast furnace gas.

[High temperature gas temperature]
The temperature of the high-temperature gas discharged from the high-temperature gas nozzle 30 is not particularly limited, and can be any temperature as long as the fuel gas can be ignited. However, since the ignition temperature of the gas used as the fuel gas is generally about 500 to 700 ° C., it is preferable that the temperature of the high temperature gas is 800 ° C. or higher. Sufficient ignitability can be ensured by setting the temperature of the high temperature gas to 800 ° C. or higher. On the other hand, the upper limit of the temperature of the high temperature gas is not particularly limited and can be any temperature. However, considering the materials of the combustion chamber 40 and the high temperature gas nozzle 30, the temperature of the high temperature gas is preferably 1000 ° C. or lower. In the present invention, since the fuel gas is ignited by the high temperature gas, the temperature of the final high-speed jet flame 60 can be set to a high temperature of, for example, 1400 ° C. or higher even if the temperature of the high temperature gas itself is 1000 ° C. or lower.

[Temperature control of high temperature gas]
The temperature of the high temperature gas can be adjusted by any method, but it can be easily performed by controlling the supply amount of the temperature adjusting air supplied from the temperature adjusting air supply unit 70. The control of the supply amount is preferably performed based on the temperature measured by the temperature measuring means 71, and more preferably the temperature of the high temperature gas is controlled to be 800 ° C. or higher and 1000 ° C. or lower. The control can be performed by any control means such as a sequencer.

[Nitrogen purge]
When the temperature measured by the temperature measuring means 71 becomes 780 ° C. or lower, it is preferable to perform nitrogen purging to the piping for supplying the fuel gas to the fuel gas nozzle 10 and the high temperature gas generating burner 50 to shut off combustion. The nitrogen purge can be performed by any method. For example, the nitrogen gas supply pipe for purging may be connected in the middle of the pipe for supplying fuel gas, and the valve may be opened to send the nitrogen gas to the pipe for supplying fuel gas as needed.

[Ratio of fuel gas amount]
The ratio of the amount of the high temperature gas generating fuel gas supplied to the high temperature gas generating burner 50 to the amount of the fuel gas supplied to the fuel gas nozzle 10 is preferably 10 to 30%.

[Air ratio]
It is preferable to control the amount of combustion air discharged from the air nozzle 20 according to the amount of fuel gas discharged from the fuel gas nozzle 10 so that the air ratio is 0.7 to 1.5. Here, the air ratio is the ratio of the actual amount of combustion air when the theoretical amount of air required for the fuel gas to completely burn is set to 1. When the air ratio is 0.7 or more, the fuel gas can be appropriately burned. Further, by setting the air ratio to 1.5 or less, it is possible to prevent the temperature of the high-speed jet flame 60 from dropping due to excess air.

[Discharge rate]
The faster the speed of the formed high-speed jet flame 60, the higher the heat transfer efficiency. Therefore, the discharge speed of the high temperature gas discharged from the high temperature gas nozzle 30 is preferably high, and particularly preferably 100 m / s or more. Similarly, it is preferable that the discharge speed of the fuel gas discharged from the fuel gas nozzle 10 and the discharge speed of the combustion air discharged from the air nozzle 20 are 50 Nm / s or more.

In a conventional general burner that discharges combustion gas and air to burn, when the discharge speed is increased, the balance between the combustion speed and the gas flow velocity is broken, and the flame is blown downstream and extinguished, so-called extinguishing occurs. It ends up. Therefore, the discharge rate cannot be significantly increased with the conventional burner, and therefore, there is a limit to the improvement of the heating efficiency. However, in the burner of the present invention, since the high temperature gas is discharged together with the fuel gas and ignited by the high temperature gas, even if the fuel gas or air is discharged at a high speed of 50 Nm / s or more, the jet is stably jetted without being blown out. A flame can be formed. Both the discharge speed of the fuel gas and the discharge speed of the combustion air can be set to be equal to or higher than the speed of sound. Here, the "sound velocity" means the sound velocity at individual temperatures of the combustion air and the fuel gas to be discharged.

Next, in order to confirm the effect of the present invention, the following experiment was carried out.

Using the burner shown in FIG. 1, a steel material having a thickness of 10 mm, a length of 300 mm, and a width of 300 mm placed horizontally on the heat insulating material is heated, and the temperature change of the steel plate at that time is measured by a thermocouple attached to the steel plate. Measured in (Example). The burner was installed at a position 500 mm above the steel plate so that a downward flame was discharged. As the fuel gas, M gas having a calorific value of 2400 kcal / Nm ³ was used, and heating was performed under the condition of a total combustion amount of 100,000 kcal / h. At that time, the discharge speed of the fuel gas and the combustion air is 150 Nm / s, the air ratio is 1.05, the temperature of the high temperature gas for igniting the fuel gas is 820 ° C., and the fuel gas supplied to the fuel gas nozzle. The ratio of the amount of the high-temperature gas-generating fuel gas supplied to the high-temperature gas-generating burner to the amount was 15%, and the flow velocity of the gas discharged from the high-temperature gas nozzle was 109 m / s.

For comparison, a similar steel material was heated using a double circular tube type premixed diffusion type burner without a high temperature gas nozzle (comparative example). The amount of fuel gas used in the examples and the comparative examples was the same. The discharge speed of the fuel gas and the combustion air in the comparative example was set to 10 Nm / s.

As a result of the experiment, in the burner of the example, a stable flame could be formed in spite of the high discharge speed of the fuel gas from the nozzle. In addition, the time required to heat the steel sheet from room temperature to 1000 ° C. was reduced to 5.3 minutes in the comparative example and 1.7 minutes in the example, which is about 1/3. That is, the amount of gas used for heating to the same temperature can be reduced to about 1/3. In addition, since the high-speed burner can be heated by high heat transfer, it can be heated to a higher temperature when it is heated using the same fuel gas. Under the present conditions, the temperature of the steel sheet was saturated at 1100 ° C. in the burner of the comparative example, whereas the burner of the example could be heated to about 1300 ° C.

1 Burner 10 Fuel gas nozzle 11 Fuel gas supply unit 12 Fuel gas chamber 15 Fuel gas flow 20 Air nozzle 21 Combustion air supply unit 22 Combustion air chamber 25 Combustion air flow 30 High temperature gas nozzle 35 High temperature gas flow 40 Combustion chamber 41 Insulation wall 50 Burner for high temperature gas generation 51 Fuel gas nozzle for high temperature gas generation 52 Air nozzle for high temperature gas generation 53 Swing blade 54 Pilot burner 55 Flame 60 High temperature jet flame 70 Air supply unit for temperature adjustment 71 Temperature measuring means

Claims (15)

A fuel gas nozzle that discharges fuel gas and
An air nozzle that discharges combustion air and
A burner provided with a high-temperature gas nozzle that discharges high-temperature gas for igniting the fuel gas.
The high temperature gas is combustion exhaust gas,
Further, a burner for generating high temperature gas for generating the high temperature gas and a burner for generating high temperature gas,
A combustion chamber to which the high temperature gas generation burner is connected is provided.
A burner in which a combustion air chamber for cooling the combustion chamber and preheating the combustion air is provided outside the combustion chamber. The burner according to claim 1 , wherein the fuel gas nozzle and the air nozzle are Laval nozzles. The burner according to claim 1 or 2 , wherein a fuel gas chamber for preheating the fuel gas is provided outside the combustion air chamber. Further, a temperature adjusting air supply unit that supplies temperature adjusting air to the combustion chamber, and a temperature adjusting air supply unit,
The burner according to any one of claims 1 to 3 , further comprising a temperature measuring means for measuring the temperature in the combustion chamber. The heating method using the burner according to any one of claims 1 to 4.
A heating method in which the temperature of the high temperature gas is 800 ° C. or higher. The heating method using the burner according to claim 4.
The temperature of the high temperature gas is controlled to 800 ° C. or higher and 1000 ° C. or lower by controlling the supply amount of the temperature adjusting air supplied from the temperature adjusting air supply unit based on the temperature measured by the temperature measuring means. How to heat. The heating method according to claim 6.
A heating method in which the ratio of the amount of high-temperature gas-producing fuel gas supplied to the high-temperature gas-generating burner to the amount of the fuel gas supplied to the fuel-gas nozzle is 10 to 30%. The heating method according to claim 6.
A heating method in which when the temperature measured by the temperature measuring means becomes 780 ° C. or lower, nitrogen purging is performed on the fuel gas nozzle and the pipe for supplying fuel gas to the high temperature gas generation burner to shut off combustion. The heating method according to claim 5 or 6 , wherein the discharge speed of the high temperature gas discharged from the high temperature gas nozzle is 100 m / s or more. It is a heating method using a burner.
The burner
A fuel gas nozzle that discharges fuel gas and
An air nozzle that discharges combustion air and
A high-temperature gas nozzle for discharging high-temperature gas for igniting the fuel gas is provided.
The high temperature gas is combustion exhaust gas,
Further, a burner for generating high temperature gas for generating the high temperature gas and a burner for generating high temperature gas,
The combustion chamber to which the high temperature gas generation burner is connected and
A temperature control air supply unit that supplies temperature control air to the combustion chamber,
A temperature measuring means for measuring the temperature in the combustion chamber is provided.
The temperature of the high temperature gas is controlled to 800 ° C. or higher and 1000 ° C. or lower by controlling the supply amount of the temperature adjusting air supplied from the temperature adjusting air supply unit based on the temperature measured by the temperature measuring means. And
A heating method in which when the temperature measured by the temperature measuring means becomes 780 ° C. or lower, nitrogen purging is performed on the fuel gas nozzle and the pipe for supplying fuel gas to the high temperature gas generation burner to shut off combustion. The heating method according to claim 10.
A heating method in which the fuel gas nozzle and the air nozzle are Laval nozzles. The heating method according to claim 10 or 11 , wherein the discharge rate of the high temperature gas discharged from the high temperature gas nozzle is 100 m / s or more. The discharge speed of the fuel gas discharged from the fuel gas nozzle is 50 Nm / s or more.
The heating method according to any one of claims 5 to 12 , wherein the discharge rate of the combustion air discharged from the air nozzle is 50 Nm / s or more. The discharge speed of the fuel gas discharged from the fuel gas nozzle is equal to or higher than the speed of sound.
The heating method according to claim 13 , wherein the discharge speed of the combustion air discharged from the air nozzle is equal to or higher than the speed of sound. The claim that the amount of the combustion air discharged from the air nozzle is controlled according to the amount of the fuel gas discharged from the fuel gas nozzle so that the air ratio is 0.7 to 1.5. The heating method according to any one of 5 to 14.

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