JPH09170749A - Heating furnace and its operation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a reduction in combustion efficiency to be prevented even if an arrangement of heated item or aging variation in a flame or composition of fuel shows a detrain variation by a method wherein a means for sensing ignitable components is arranged at combustion discharged gas output side of a heat accumulation member and a combustion air supplying means is arranged at a combustion discharged gas input side. SOLUTION: Auxiliary combustion air supplying positions are placed within fluid passages 13a, 13b, 13c and 13d of the heat accumulating members 4a, 4b, 4c and 4d near a furnace 1. Under this state, in the case that non-ignited components are detected in the combustion discharged gas, auxiliary combustion air for use in igniting not-yet ignited ignitable components is supplied to a combustion discharged gas input side, namely, supplied to the furnace 1, resulting in that not-yet ignited ignitable components contained in the combustion discharged gas are ignited at an input side of the heat accumulating member 4. Then, heat energy recovered by the heat accumulating member 4 is applied for pre-heating of the combustion air when combustion is carried out with a heat accumulating type combustion burner having heat accumulating member 4, resulting in that a combustion efficiency at the furnace 1 is not reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating furnace provided with a regenerative combustion burner and its operating method, and more particularly to a heating furnace and its operating method capable of preventing unburned combustible components from being discharged together with combustion exhaust gas. Regarding the method.

[0002]

2. Description of the Related Art A heating furnace equipped with a regenerative combustion burner is
The sensible heat of high-temperature combustion exhaust gas is stored in the heat storage body attached to the combustion burner, and the combustion air is preheated to a high temperature through this heat storage body during combustion and used for combustion. It is used in steelworks.

When heating an object to be heated in a heating furnace provided with a regenerative combustion burner, fuel and combustion air are supplied in a mixed state, and combustion occurs near the surface of the object to be heated. If so, there is a problem that the surface of the object to be heated is easily oxidized, the generated scale remains on the surface of the product, and the quality is deteriorated.

Due to the above-mentioned problems, Japanese Patent Laid-Open No. 7-
In the heat storage type alternating combustion burner for a heating furnace disclosed in Japanese Patent No. 102313, as shown in FIG. 4, a fuel supply hole 31 is provided so as to protrude from the furnace wall 32 into the furnace 33 by about 30 cm, and the fuel 34 is not covered. The heating object 35 is sprayed so as to cover it.

The combustion air holes 36 are arranged so as not to protrude from the furnace wall 32 into the furnace 33, and the combustion air 37 is provided.
Is provided so as to be injected to a position farther from the object to be heated 35 than the fuel 34, and the flame 38 generated by combustion is blocked by the fuel 34 and does not directly hit the object 35 to be heated. ing. That is, the atmosphere in the furnace 33 near the object 35 to be heated is a reducing atmosphere,
This suppresses the oxidation of the object 35 to be heated.

[0006]

However, in the case of heating an object to be heated in the heating furnace in which the heat storage type alternating combustion burner for heating furnace disclosed in the above-mentioned Japanese Patent Laid-Open No. 7-102313 is arranged, the following is required. There was a problem. That is, depending on the arrangement of the heated object in the furnace and the degree of change over time of the flame of the combustion burner, the fuel injected into the furnace is not immediately burned, so the combustion exhaust gas containing unburned combustible components is However, since it is sucked by another combustion burner in the exhaust state and discharged to the outside of the furnace, there is a problem that the combustion efficiency becomes low.

Further, even when a heat storage type combustion burner other than the above is used, when the composition of the fuel fluctuates, unburned combustible components are generated even if burning at a constant air ratio. However, there is a problem that the combustion efficiency is reduced due to this.

The present invention has been made in order to solve the above-mentioned problems of the prior art. Even if the arrangement of the object to be heated, the flame changes with time, or the fuel composition changes, the combustion efficiency is improved. It is an object of the present invention to provide a heating furnace and a method of operating the heating furnace that do not decrease.

[0009]

A heating furnace according to the present invention is a heating furnace in which one or more sets of regenerative combustion burners that perform alternating combustion are arranged. Combustible component detection means for detecting the components is provided, and combustion air supply means for completely burning the combustible components in the combustion exhaust gas is provided on the combustion exhaust gas inlet side of the heat storage body.

In the heating furnace according to the present invention, the combustible component detecting means detects the combustible component contained in the combustion exhaust gas after passing through the heat storage body. When it is determined that the combustible component is contained, in order to completely burn the combustible component by the combustion air supply means provided on the heat storage body combustion exhaust gas inlet side of the regenerative combustion burner that is discharging the combustion exhaust gas. Supply the combustion air.

Therefore, the sensible heat in the combustion exhaust gas generated by the combustion of the combustible component can be stored in the heat storage body without the combustible component being discharged together with the combustion exhaust gas to the outside of the furnace, so that the combustion efficiency is improved. Increase.

A theoretical air amount calculating means for calculating a theoretical air amount for completely burning the combustible component detected by the combustible component detecting means is provided.

In the heating furnace according to the present invention, the theoretical air amount calculating means calculates the theoretical air amount for completely combusting the combustible components, and the combustion air is supplied based on the calculated theoretical air amount. Since the combustion air is not excessively supplied, the heat storage body is not cooled by the excess air, and the sensible heat contained in the combustion exhaust gas can be efficiently stored.

A first heating furnace operating method according to the present invention is a heating furnace operating method in which one or more sets of alternating combustion type regenerative combustion burners are arranged. When a combustible component in the combustion exhaust gas is detected on the heat storage medium combustion exhaust gas outlet side of the combustion burner and it is determined that the combustion exhaust gas contains a combustible component, the heat storage type combustion exhaust gas inlet side of the heat storage type combustion burner. In the above, the combustion air for completely burning the combustible components in the combustion exhaust gas is supplied.

By this operating method, the sensible heat in the combustion exhaust gas generated by the combustion of the combustible component can be stored in the heat storage body without the combustible component being discharged together with the combustion exhaust gas outside the furnace. Increases combustion efficiency.

A second aspect of the present invention is a method of operating a heating furnace equipped with a second regenerative combustion burner, which is a method of operating a heating furnace in which one or more sets of regenerative combustion burners that perform alternating combustion are arranged. At the discharge side of the heat storage type combustion exhaust gas of the heat storage type combustion burner that is discharging, the combustible component in the combustion exhaust gas is detected, and when it is determined that the combustible component is contained in the combustion exhaust gas, the heat storage type combustion burner On the inlet side of the heat storage medium combustion exhaust gas, the combustible components in the combustion exhaust gas are completely burned, and the oxygen-containing gas is supplied at a temperature at which the temperature of the combustion exhaust gas after complete combustion does not exceed the heat resistant temperature of the heat storage body. .

By this operating method, the sensible heat in the combustion exhaust gas generated by the combustion of the combustible component can be stored in the heat storage body without the combustible component being discharged together with the combustion exhaust gas outside the furnace. Increases combustion efficiency.

Further, since the temperature of the heat storage body does not exceed the heat resistant temperature due to the combustion exhaust gas after the combustible components are burned, the life of the heat storage body does not decrease.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A method of operating a heating furnace equipped with a regenerative combustion burner according to a first embodiment of the present invention will be described with reference to FIG. In the heating furnace 1 of FIG. 1, combustion is carried out by the regenerative combustion burners 2a and 2c, and the regenerative combustion burner 2b and the regenerative combustion burner 2c paired with the regenerative combustion burner 2a are paired. Regenerative combustion burner 2
The state in which the combustion exhaust gas is discharged is shown in d. And, it is an example in the case of operating in an almost complete combustion state with an air ratio of about 1.05.

In this operating method of the heating furnace, the combustion exhaust gas 3 generated in the regenerative combustion burners 2a and 2c burning in the heating furnace 1 is the regenerative combustion burners 2b and 2d discharging the combustion exhaust gas 3. Heat storage bodies 4b and 4d
To reach the combustion exhaust gas main pipe 6 through the respective switching valves 5A and 5B, and is discharged to the outside of the system. Then, when the composition of the fuel changes, the unburned combustible components may be discharged to the outside of the system through the above-mentioned route.

The combustion exhaust gas main pipe 6 includes a sampling pipe 7
Is provided, and a component analyzer 8 for detecting unburned combustible components in the combustion exhaust gas is connected to the sampling pipe 7. An infrared analyzer or the like for CO gas may be used as the component analyzer 8.

The component analyzer 8 detects the concentration of unburned combustible components in the combustion exhaust gas 3. Then, when an unburned combustible component is detected, a signal is sent to the auxiliary combustion air valve controller 9, and a valve opening command is issued from the auxiliary combustion air valve controller 9 for auxiliary combustion. The air valves 10b and 10d are opened, and the auxiliary combustion air passes through the auxiliary combustion air pipes 12b and 12d branched from the combustion air pipe 11 to discharge the combustion exhaust gas to the regenerative combustion burners 2b and 2d. Each heat storage body 4b and 4
It is supplied to the side closer to the furnace 1 of d.

On the other hand, the auxiliary combustion air valves 10a and 10c for the regenerative combustion burners 2a and 2c during combustion are closed.

The auxiliary combustion air is supplied while the combustion exhaust gas is being discharged by the regenerative combustion burners 2b and 2d and the component analyzer 8 detects unburned combustible components in the combustion exhaust gas. Continued inside.

Further, when the heat storage type combustion burner for combustion is switched from the heat storage type combustion burners 2a and 2c to 2b and 2d, when an unburned combustible component is detected by the component analyzer 8, it is assisted. A command to open the valve from the combustion air valve controller 9 is issued by the auxiliary combustion air valves 10a and 10c.
Emitted to Then, the auxiliary combustion air valves 10a and 10c are opened, and the auxiliary combustion air is branched from the combustion air pipe 11 and the auxiliary combustion air pipes 12a and 1 are branched.
Regenerative bodies 4a and 4c of the regenerative combustion burners 2a and 2c, respectively, which discharge combustion exhaust gas through 2c.
Is supplied to the side closer to the furnace 1.

On the other hand, the auxiliary combustion air valves 10b and 10d for the regenerative combustion burners 2b and 2d during combustion are closed.

In FIG. 1, the auxiliary combustion air is supplied to the burner port, which is located in the fluid passages 13a, 13b, 13c and 13d near the furnace 1 side of the heat storage bodies 4a, 4b, 4c and 4d. It may be in the furnace 1a close to.

In this embodiment, when an unburned combustible component is detected in the combustion exhaust gas, the auxiliary combustion air for burning the unburned combustible component is used as the auxiliary combustion air for the heat storage body at the combustion exhaust gas inlet side (furnace side). ), The unburned combustible components in the combustion exhaust gas are combusted on the inlet side of the heat storage body.

Therefore, the amount of sensible heat possessed by the combustion exhaust gas passing through the heat storage body increases, and the amount of heat recovered in the heat storage body increases.

The heat energy recovered by the heat storage body is used for preheating the combustion air when combustion is performed by the heat storage type combustion burner having the heat storage body.

Therefore, since the unburned combustible components are not discharged to the outside of the system and are used for combustion, the combustion efficiency of the furnace does not decrease.

In FIG. 1, reference numerals 14a, 14b, 14
c and 14d are fuel cutoff valves.

In FIG. 1, four burners (2
However, the number of burners in the same combustion zone is the same group, and the combustion exhaust gas of that group is analyzed by one analyzer. It may be analyzed to control the supply of auxiliary combustion air.

Further, it is not always necessary to provide an auxiliary combustion air valve for each burner, and one auxiliary combustion air valve is provided for all the burners of the same group to supply auxiliary combustion air. Good.

Next, a method of operating the heating furnace having the regenerative combustion burner according to the second embodiment of the present invention will be described with reference to FIG. In the heating furnace 1 of FIG. 2, as in the case of FIG. 1, the regenerative combustion burners 2a and 2c burn, and the regenerative combustion burner 2b and the regenerative combustion paired with the regenerative combustion burner 2a. It shows a situation in which combustion exhaust gas is being discharged by the regenerative combustion burner 2d paired with the burner 2c.

In FIG. 2, since the same equipment as that in FIG. 1 is often used, the same reference numerals as those in FIG. 1 are used for the same equipment, and detailed description thereof will be omitted.

In this embodiment, the component analyzer 8
The value of the concentration of the unburned combustible component detected by is sent to the theoretical air amount calculator 15, and the unburned combustible component is completely burned from this value and the preset combustion exhaust gas generation amount per unit time. The theoretical air amount for the operation is calculated. When CO is used to detect unburned combustible components,
It may be calculated based on the following equation (1).

Q = {G ₀ · [CO] / (2 × 0.21)} · k (1) However, Q: auxiliary combustion air flow rate (Nm ³ / h) G ₀ : theoretical exhaust gas Flow rate (Nm ³ / h) [CO]: CO concentration (ratio) k: Correction count The correction count k is determined according to the furnace conditions.

Then, the calculated theoretical air amount value is sent to the auxiliary combustion air flow rate controller 16, and the auxiliary combustion air flow rate controller 16 receives the theoretical air amount signal from the auxiliary combustion air flow rate controller 16. A command is issued to the adjusting valve 20, and the auxiliary combustion air flow rate adjusting valve 2 is supplied in accordance with the calculated theoretical air amount value.
The opening degree of 0 is adjusted. At the same time, the auxiliary combustion air flow rate controller 16 issues a command to open the auxiliary combustion air valves 17b and 17d to open the auxiliary combustion air valve 17b.
And 17d are opened.

Then, the auxiliary combustion air passes through the auxiliary combustion air branch pipes 19b and 19d branched from the auxiliary combustion air main pipe 18 to discharge the combustion exhaust gas from the regenerative combustion burners 2b and 2d, respectively. Heat storage bodies 4b and 4
It is supplied to the side closer to the furnace 1 of d.

The auxiliary combustion air is supplied while the combustion exhaust gas is being discharged by the regenerative combustion burners 2b and 2d, and the component analyzer 8 detects unburned combustible components in the combustion exhaust gas. Continued inside.

The auxiliary combustion air valves 17a and 17c for supplying the auxiliary combustion air to the regenerative combustion burners 2a and 2c which are burning during this period are closed.

Further, when the heat storage type combustion burner for combustion is switched from the heat storage type combustion burners 2a and 2c to 2b and 2d, when an unburned combustible component is detected by the component analyzer 8, it is assisted. Combustion air flow controller 1
The command to open the valve from 6 is the auxiliary combustion air flow rate adjustment valve 2
The opening degree of the auxiliary combustion air flow rate adjusting valve 20 is adjusted in accordance with the calculated theoretical air amount value which is emitted to zero. At the same time, the auxiliary combustion air flow rate controller 16 issues a valve opening command to the auxiliary combustion air valves 17a and 17c, and the auxiliary combustion air valves 17a and 17c are opened.

Then, the auxiliary combustion air passes through the auxiliary combustion air branch pipes 19a and 19c branched from the auxiliary combustion air main pipe 18 to discharge the combustion exhaust gas from each of the regenerative combustion burners 2a and 2c. Heat storage bodies 4a and 4
It is supplied to the side closer to the furnace 1 of c.

The auxiliary combustion air is supplied while the combustion exhaust gas is being discharged by the regenerative combustion burners 2a and 2c, and the component analyzer 8 detects unburned combustible components in the combustion exhaust gas. Continued inside.

The auxiliary combustion air valves 17b and 17d for supplying auxiliary combustion air to the regenerative combustion burners 2b and 2d which are burning during this period are closed.

In FIG. 2, the auxiliary combustion air supply position is in the fluid passages 13a, 13b, 13c and 13d close to the furnace 1 side of the heat storage bodies 4a, 4b, 4c and 4d. It may be located near the burner opening of 1a.

In this embodiment, when the unburned combustible component is detected in the combustion exhaust gas, the theoretical air amount for completely burning the unburned combustible component is calculated,
Since the auxiliary combustion air according to this theoretical air amount is supplied to the combustion exhaust gas inlet side (furnace side) of the heat storage body, unburned combustible components in the combustion exhaust gas are burned at the heat storage body inlet side, Excess air is not contained in the combustion exhaust gas.

Therefore, the sensible heat amount of the combustion exhaust gas passing through the heat storage body increases and the temperature of the combustion exhaust gas does not decrease due to excess air, so that the heat recovery amount in the heat storage body is the first embodiment. It is improved more than when the above embodiment is carried out. Therefore, the combustion efficiency of the furnace does not decrease.

Next, a method of operating the heating furnace equipped with the regenerative combustion burner according to the third embodiment of the present invention will be described with reference to FIG. In this embodiment, in order to burn the unburned combustible components in the combustion exhaust gas, the auxiliary combustion air pipe is connected to the fluid passage on the combustion exhaust gas inlet side of the heat storage body, and is not contained in the combustion exhaust gas by the component analyzer. Since the auxiliary combustion air is supplied to the fluid passage when the combustible component of combustion is detected is the same as in the first embodiment or the second embodiment described above, the same. The description of the part that is omitted is omitted, and the characteristic point of this embodiment will be described based on the cross-sectional view of the regenerative combustion burner 2 in FIG. In the operating method of the heating furnace provided with the regenerative combustion burner, the temperature of the combustion exhaust gas after the auxiliary combustion air is supplied from the auxiliary combustion air pipe 21 to the fluid passage 13 to burn the unburned combustible components Is detected by a thermometer 22 provided in the fluid passage 13,
When the detected temperature of the combustion exhaust gas exceeds the heat resistant temperature of the heat storage body 4, the room temperature air pipe 2 connected to the fluid passage 13
3, the normal temperature air is supplied to the fluid passage 13 in an amount such that the combustion exhaust gas temperature detected by the thermometer 22 falls below the heat resistant temperature of the heat storage body 4.

The gas supplied from the room temperature air pipe 23 is not limited to room temperature air as long as the temperature of the combustion exhaust gas can be adjusted, and may be nitrogen gas, for example.

Further, without using the thermometer 22 and the room temperature air pipe 23, a predetermined amount of cold air is blown from the auxiliary combustion air pipe 21 in accordance with the separately measured furnace temperature condition and the amount of unburned gas. You may do it.

In addition to the effects of the first and second embodiments, this embodiment has the effect of not shortening the life of the heat storage body 4.

[0054]

EXAMPLE A furnace having a width of 2 m, a length of 4 m and a height of 2 m was provided, and a pair of alternating combustion type regenerative combustion burners were provided on the furnace wall in the width direction with an axial center distance of 1 m. In a batch-type heating furnace, an operation of burning 2600 kcal / Nm ³ of M gas (steel mill by-product mixed gas) at an air ratio of 0.95 was performed. At this time, the temperature of the combustion exhaust gas measured by a thermometer installed on the combustion exhaust gas inlet side of the heat storage body was 1370 ° C. (average temperature within a certain period of time).

Further, when the CO concentration in the combustion exhaust gas was measured by the CO meter installed in front of the combustion exhaust gas discharge blower, the CO concentration was 350 ppm, so that the unburned combustible component was completely burned. , 8 Nm ³ / h of auxiliary combustion air was supplied.

As a result, the CO concentration measured by the CO meter became almost 0, but the combustion exhaust gas temperature after completely burning the unburned combustible components measured by the thermometer was the temperature of the regenerator. 1400 which is the maximum temperature based on the heat resistant temperature
Since the temperature exceeds ℃, in order to reduce the temperature of the combustion exhaust gas on the combustion exhaust gas inlet side of the heat storage body, auxiliary combustion air is
When supplied at Nm ³ / h, the combustion exhaust gas temperature on the combustion exhaust gas inlet side of the heat storage body was 1375 ° C., which was less than the upper limit temperature of 1400 ° C. That is, by doing so, it is possible to perform an operation in which the life of the heat storage body is not reduced and the combustion efficiency is not reduced.

The heat-resistant temperature of the heat storage body, which is the basis of the upper limit temperature of the combustion exhaust gas, is based on the material of the heat storage body used.

[0058]

According to the present invention, the combustion efficiency is increased and the heat recovery efficiency is also increased.

Further, when it is attempted to prevent the object to be heated from being oxidized, the combustion efficiency does not decrease.

Further, even if the unburned combustible components are completely burned, the life of the heat storage body does not decrease.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for operating a heating furnace according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a heating furnace operating method according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a heating furnace operating method according to a third embodiment of the present invention.

FIG. 4 is an explanatory view of a conventional heat storage type alternating combustion burner.

[Explanation of symbols]

 1 heating furnace 2a, 2b, 2c, 2d heat storage type combustion burner 3 combustion exhaust gas 4a, 4b, 4c, 4d heat storage body 5A, 5B switching valve 6 combustion exhaust gas main 7 sampling tube 8 component analyzer 9 auxiliary combustion air valve Controller 10a, 10b, 10c, 10d Auxiliary combustion air valve 11 Combustion air piping 12a, 12b, 12c, 12d Auxiliary combustion air piping 13a, 13b, 13c, 13 Fluid passage 14a, 14b, 14c, 14d Fuel cutoff valve 15 theoretical air amount calculator 16 auxiliary combustion air flow rate controller 17a, 17b, 17c, 17d auxiliary combustion air valve 18 auxiliary combustion air main 19a, 19b, 19c, 19d auxiliary combustion air branch pipe 20 auxiliary combustion Air flow control valve 21 Auxiliary combustion air piping 22 Thermometer 23 Room temperature air piping

Claims (4)

[Claims] 1. A heating furnace in which one or more sets of regenerative combustion burners that perform alternating combustion are arranged, and a combustible component detection means for detecting a combustible component in the combustion exhaust gas is provided on the combustion exhaust gas outlet side of the heat storage body. A heating furnace, characterized in that combustion air supply means for completely burning combustible components in the combustion exhaust gas is provided on the combustion exhaust gas inlet side of the heat storage body. 2. A theoretical air amount calculating means for calculating a theoretical air amount for completely burning the combustible component detected by the combustible component detecting means is provided.
A heating furnace according to item 1. 3. A method of operating a heating furnace in which one or more sets of regenerative combustion burners that perform alternating combustion are arranged. In the case where it is determined that the combustible component is contained in the combustion exhaust gas, the combustible component in the combustion exhaust gas is completely combusted on the heat storage body combustion exhaust gas inlet side of the regenerative combustion burner. A method of operating a heating furnace, characterized by supplying combustion air. 4. In a method of operating a heating furnace in which one or more sets of regenerative combustion burners that perform alternating combustion are arranged, a regenerator of a regenerative combustion burner that discharges flue gas is discharged from the flue gas outlet side. The combustible component in the combustion exhaust gas is completely burned when the combustible component is detected in the combustion exhaust gas, and it is determined that the combustion exhaust gas contains the combustible component. A method for operating a heating furnace, comprising supplying the oxygen-containing gas at a temperature at which the temperature of the combustion exhaust gas after complete combustion does not exceed the heat resistant temperature of the heat storage body.