JPH06265117A - Heating furnace - Google Patents

Abstract

PURPOSE:To make a compact size and a low cost of a heating furnace by a method wherein the heating furnace is divided into a combustion chamber for igniting fuel and a heating chamber for heating heated item with combustion gas ignited at the combustion chamber. CONSTITUTION:A refractory partition wall 2 is arranged within a heating furnace 1 formed by refractory furnace walls so as to make a combustion chamber 3 and a heating chamber 4. Both ends of the combustion chamber 3 and the heating chamber 4 are connected by a combustion gas supplying passage 5 and a combustion gas circulating passage 6. A burner 7 is arranged at one end of the combustion chamber 3, a fuel supplying pipe 8 and a combustion supporting gas supplying pipe 9 are connected so as to supply both fuel and combustion supporting gas and then the combustion of fuel with oxygen is carried out within the combustion chamber 3. In turn, partition walls 10 are arranged at both ends of the heating chamber 4 so as to make a uniform distribution of combustion gas into the heating chamber 4 and then a heated item 11 loaded from the burner 7 into the heating chamber 4 through a gas radiation heat transfer of the combustion gas is heated. With such an arrangement as above, concentrated burner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a general heating furnace such as a heating furnace, a soaking furnace and a heat treatment furnace for heating an object to be heated such as a slab, a billet and a bloom to a predetermined target temperature.

[0002]

2. Description of the Related Art Heretofore, in this type of heating furnace, an air combustion method has been generally used in which a fuel is burned with air to heat an object to be heated. Recently, however, the fuel is pure oxygen or oxygen-enriched air. Attention has been paid to an oxy-fuel combustion method in which a material to be heated is burned by being burned by the above. Compared with the conventional air combustion method, this oxyfuel combustion method has a combustion gas amount of about 1/4, which is less than that of carbon dioxide gas (CO
₂ ) and the concentration of water vapor (H ₂ O) are high, the reduction of exhaust gas heat loss and the increase of radiant electric heat in the furnace have a great energy saving effect. It has the advantage of being easy. On the other hand, this oxyfuel combustion system has a problem that it cannot be applied to a heating furnace due to high temperature and high load combustion, poor uniform heating of the object to be heated, and high nitrogen oxide (NO _x ) concentration. there were.

On the other hand, for example, JP-A-54-128
There is a heating furnace combustion method as disclosed in Japanese Patent No. 834. The feature of this technology is to suppress high temperature hot gas and nitrogen oxides due to oxygen combustion, and to achieve this,
As shown in FIG. 4, the low-temperature combustion exhaust gas of the heating furnace 1 is pressurized by the circulation fan 18 and mixed with pure oxygen, and then supplied to the burner 7 of the heating furnace 1 to be mixed with fuel and used for combustion. Is.

However, in the above combustion method, pure oxygen is diluted with combustion exhaust gas and used as simulated air having an oxygen concentration of 21%, so that a large number of burners and wide combustion air are required as in the conventional air combustion method. As a result, there is a problem that the heating furnace cannot be made compact.

[0005]

SUMMARY OF THE INVENTION The present invention was devised to solve the above-mentioned problems, and its purpose is to make the heating furnace compact by increasing the low furnace height of the heating furnace and integrating burners. An object of the present invention is to provide a heating furnace whose cost is reduced.

[0006]

SUMMARY OF THE INVENTION The present invention is based on the following matters. (1) A heating furnace for heating an object to be heated by burning a fuel with a combustion-supporting gas containing a high concentration of oxygen, the combustion chamber in which the heating furnace burns the fuel, and the combustion in the combustion chamber. It must be installed separately from the heating chamber that heats the object to be heated with gas. If necessary, (2) a combustion gas circulation furnace for circulating combustion gas from the heating chamber to the combustion chamber is provided. (3) The combustion chambers divided by partition walls are provided on both outsides of the overheating chamber. (4) A carbon dioxide gas recovery device is provided in the flue of the heating furnace, and a combustion gas bypass circuit for diverting the combustion gas from the combustion chamber to the flue gas upstream of the carbon dioxide recovery device is provided. .

Since the heating furnace of the present invention has a structure in which the conventional heating furnace is divided into a combustion chamber and a heating chamber, a high load and stoichiometric (theoretical) combustion of fuel can be carried out in the combustion chamber, and the heating chamber has carbon dioxide gas. And the furnace height can be lowered in inverse proportion to the steam concentration. Further, since the low temperature combustion gas is circulated between the heating chamber and the combustion chamber, the high temperature combustion gas and the nitrogen oxides at the time of oxygen combustion can be suppressed. Further, since the combustion chambers divided by the partition walls are provided on both outer sides of the heating chamber, the furnace wall is reduced and the facility cost and the radiant heat of the furnace body can be reduced. Furthermore, since the combustion gas in the combustion chamber can be directly sent to the carbon dioxide recovery device by a bypass, the amount of carbon dioxide recovered can be made constant regardless of the operating load of the heating furnace.

[0008]

EXAMPLES The present invention will now be described in more detail based on examples. As shown in FIGS. 1 and 2, a partition wall 2 of a refractory material is provided in a heating furnace 1 formed of a furnace wall of the refractory material to form a combustion chamber 3 and a heating chamber 4. Both ends of are connected by a combustion gas supply path 5 and a combustion gas circulation path 6. Further, a burner 7 is arranged at one end side of the combustion chamber 3 to connect a fuel supply pipe 8 and a combustion-supporting gas supply pipe 9 to supply fuel and combustion-supporting gas to perform oxygen combustion of the fuel in the combustion chamber 3. .

As the fuel, various gas or liquid fuels can be generally used. However, in the case of suppressing nitrogen oxides and recovering carbon dioxide gas, impurities such as nitrogen (N) are contained in the fuel. Liquefied natural gas (LNG), liquefied petroleum gas (L)
PG) or the like is preferable. Further, the "flammable gas" as used herein is a general term for pure oxygen containing a high concentration of oxygen (O ₂ ), oxygen-enriched air, oxygen gas diluted with exhaust gas, and the like.

On the other hand, partition walls 10 are provided at both ends of the heating chamber 4 to evenly distribute the combustion gas into the heating chamber 4, and the combustion gas is transferred into the heating chamber 4 from the burner 7 side by gas radiation transmission. The heated object 11 thus heated is heated. Further, an exhaust gas flue 12 is provided on the burner 7 side in the furnace length direction of the heating furnace 1, and a gas cooler 13a, a damper 14a, an induction blower 15, and a carbon dioxide recovery device 16 are arranged in the flue 12. Further, the combustion chamber 3 and the flue 12 on the upstream side of the carbon dioxide recovery device 16 are connected by a combustion gas bypass 17, and a gas cooler 13b and a damper 14b are arranged in the combustion gas bypass 17.

Next, the operating function of the heating furnace according to the present invention will be described. First, the fuel and the combustion-supporting gas are supplied to the burner 7, and the fuel is oxy-combusted in the combustion chamber 3. As a result, the burners 7 can be integrated and the combustion chamber 3 can be made compact by high-load combustion and reduction of the amount of combustion gas by oxyfuel combustion. On the other hand, using the fluid ejection energy of the burner 7,
A low temperature combustion gas is attracted from the heating chamber 4, a high temperature oxygen combustion gas is diluted, and a combustion gas temperature suitable for heating the object 11 is adjusted.

This combustion gas is evenly distributed to the heating chamber 4 to heat the object 11 to be heated, but since it is oxygen combustion, the concentration of carbon dioxide and water vapor is about four times higher than that of air combustion, so heating is performed. Even if the furnace height of the chamber 4 is set to about 1/4, it is possible to heat the object 11 to be heated almost the same as air combustion. Further, when the high-concentration carbon dioxide gas is collected and sold to the outside, since the combustion gas bypass 17 is provided between the combustion chamber 3 and the flue 12, the burner 7 can be burned regardless of the operation load of the heating furnace 1. Therefore, the recovery amount of carbon dioxide becomes constant. Arrows in the figure show the flow of combustion gas, and double arrows show the moving direction of the object to be heated 11.

The present invention is not limited to the above-mentioned embodiment, but includes, for example, (1) connecting the combustion chamber 3 and the heating chamber 4 in series (2) the furnace body of the combustion chamber 3 and the heating chamber 4. (3) As shown in FIG. 3, the units of the combustion chamber 3 and the heating chamber 4 are connected in series in the furnace length direction to form multiple zones (4) The combustion chamber 3 in the furnace length direction (5) It is also possible to detect stoichiometric combustion by detecting the composition of the combustion gas at the outlet of the combustion chamber 3 and to carry out multi-stage combustion by supplying the combustion-supporting gas to the multi-stage combustion gas. It is of course possible to make various changes unless they are done.

[0014]

According to the heating furnace of the present invention, the following excellent effects are exhibited. (1) Since the function is divided into the combustion chamber and the heating chamber by the oxyfuel combustion type, the combustion chamber can be made compact and the burner can be integrated by high-load combustion. In addition, the heating chamber can be made compact due to the high-concentration radiation gas. (2) Since low-temperature combustion gas is circulated between the combustion chamber and the heating chamber, it is possible to suppress high-temperature combustion and nitrogen oxides peculiar to oxygen combustion. (3) Since the combustion chambers divided by partition walls are provided on both outsides of the heating chamber, the furnace wall is reduced, and the equipment cost and the radiant heat of the furnace body can be reduced. (4) Since the combustion gas bypass is provided between the combustion chamber and the flue, the carbon dioxide recovery amount can be kept constant regardless of the operating load of the heating furnace. (5) Furthermore, since stoichiometric combustion can be performed in the combustion chamber, the consumption of oxygen can be reduced and the production of nitrogen oxides and scales can be suppressed.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a heating furnace according to the present invention.

FIG. 2 is a vertical cross-sectional view of the heating furnace taken along the line AA in FIG.

FIG. 3 is a plan view showing another embodiment of the heating furnace of the present invention.

FIG. 4 is a conceptual diagram of a heating furnace showing a conventional technique.

[Explanation of symbols]

 1 Heating Furnace 2 Partition 3 Combustion Chamber 4 Heating Chamber 5 Combustion Gas Supply Path 6 Combustion Gas Circulation Path 7 Burner 8 Combustion Supply Pipe 9 Combustion Gas Supply Pipe 10 Partition Wall 11 Heated Object 12 Flue 13a, 13b Gas Cooler 14a , 14b Damper 15 Induction blow 16 Carbon dioxide recovery device 17 Combustion gas bypass 18 Circulation fan 19 Pure oxygen supply pipe

Claims (4)

[Claims] 1. A heating furnace for burning an object to be heated by burning a fuel with a combustion-supporting gas containing a high concentration of oxygen, comprising: a combustion chamber for burning the fuel in the heating furnace; A heating furnace characterized by being divided into a heating chamber for heating an object to be heated by the combustion gas burned. 2. The heating furnace according to claim 1, further comprising a combustion gas circulating furnace for circulating a combustion gas from the heating chamber to the combustion chamber. 3. The heating furnace according to claim 1, wherein the combustion chambers divided by partition walls are provided on both outer sides of the heating chamber. 4. A carbon dioxide gas recovery device is provided in a flue of a heating furnace, and a combustion gas bypass circuit for diverting combustion gas from the combustion chamber to a flue upstream of the carbon dioxide gas recovery device is provided. The heating furnace according to claim 1, 2, or 3, characterized in that.