JPH09101022A - Operating method of heat storage type burner furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of drain during operation and continue stable operation by a method wherein the time of elapse when drain eliminating set temperature has been attained has elapsed a preset burner switching time, the combustion of the burner is switched to exhaust immediately. SOLUTION: The aging of combustion waste gas temperature at the discharging side of heat storage bodies 23a, 23b from the start-up time of a heat storage type burner furnace is obtained. Then, a temperature signal, measured by a thermometer 1a or a thermometer 1b, is sent into a temperature difference operator 3, in which a drain eliminating set temperature is preset. On the other hand, the time signal of a timer 2a or a timer 2b is sent into a time difference operator 14, in which a burner switching time is preset. Then, the values of the temperature difference and the time difference are sent into a burner switching deciding device 5. On the other hand, when the time of elapse when a temperature has arrived at the drain eliminating set temperature has passed the preset burner switching time, the discharging of exhaust gas is stopped immediately and operation is switched into combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a regenerative burner furnace, and more particularly to a method of operating a regenerative burner furnace which can suppress the generation of drain during operation and can be operated stably. It is a thing.

[0002]

2. Description of the Related Art In a regenerative burner furnace, a regenerator is provided in association with each of a plurality of regenerative burners. The heat storage type burner furnace will be described below with reference to FIG. FIG. 3 is a cross-sectional view of a heating furnace using a heat storage type burner, and reference numeral 21 denotes a heat storage type burner furnace, 2
2a and 22b are heat storage type burners which alternately perform combustion and combustion exhaust gas discharge at regular intervals, and 23a and 23b.
Reference characters b are heat storage bodies attached to the heat storage type burners 22a and 22b, respectively. Further, 24a and 24b are fuel cutoff valves for fuel supplied to the regenerative burners 22a and 22b, respectively, and 25 is a regenerative burner 22a and 22b.
A switching valve for allowing combustion air or combustion exhaust gas to pass through the gas passages 26a and 26b, and 27 is an object to be heated.

FIG. 3 shows a state in which the burner 22a is in a combustion state and combustion air is supplied to the heat storage body 23a. Therefore, the combustion exhaust gas passes through the gas passage 26b of the burner 22b, the heat storage body 23b, and the switching valve 2
It is discharged through 5. Then, the combustion exhaust gas becomes the heat storage body 23.
While passing through b, the sensible heat of the combustion exhaust gas is accumulated in the heat storage body 2
Heat is stored in 3b.

Switching between combustion of the burners 22a and 22b and emission of combustion exhaust gas is performed by operating the fuel cutoff valves 24a and 24b and the switching valve 25.
For example, when switching the combustion to the burner 22b from the state where the burner 22a shown in FIG. 3 is burning,
The fuel cutoff valve 24a provided in the pipe supplying fuel to the burner 22a is closed, and the fuel cutoff valve 24b provided in the pipe supplying fuel to the burner 22b is opened. Then, the switching valve 25 is operated so that the combustion air is supplied to the burner 22b and the combustion exhaust gas is discharged from the burner 22a.

In this way, the combustion is stopped in the burner 22a where the fuel is no longer supplied, and the combustion air is heated in the burner 22b while the fuel is supplied and heat is exchanged while passing through the heat storage body 23b. Is supplied,
Combustion is started. The combustion exhaust gas generated by the combustion in the burner 22b is the gas passage 2 of the burner 22a.
After passing through the heat storage body 23a through 6a, it is discharged through the switching valve 25.

On the contrary, when the combustion is switched to the burner 22a from the state where the combustion is performed in the burner 22b, it goes without saying that the opposite valve operation to that described above may be performed.

In the heat storage bodies 23a and 23b, the combustion switching of the burners 22a and 22b is performed in a relatively short period of 30 seconds to 2 minutes, so that the heat exchange area per unit volume is large and the gas passage area is large. It is desirable to use a material having a large pressure drop and a small pressure loss when passing through a fluid.

[0008]

However, the above-mentioned conventional regenerative burner furnace has the following problems. That is, at the time of starting the furnace that starts heating from the state of normal temperature, the inside of the furnace is cold, so the temperature of the combustion exhaust gas at the heat storage body outlet side is low, and the water content and sulfur content contained in the combustion exhaust gas are condensed. Then, so-called drain occurs.

When the generated drainage stays in the gas passage on the outlet side of the heat storage body, when combustion air is supplied to this gas passage at the time of combustion, it is sprayed into the furnace together with the combustion air and lowers the combustion flame temperature. There is a problem that the heating capacity is reduced due to the limited speed. Furthermore, there is a problem that the sprayed drain adheres to the object to be heated, oxidizes the surface of the object to be heated, and the quality of the product deteriorates.

Further, there is also a problem that the generated drain corrodes the pipe or the like used as the gas passage.

In order to avoid the above problems, there are some examples in which a drain valve is provided on the outlet side of the heat storage body or a high-grade material having corrosion resistance is used as a piping material. There was a problem that the cost and maintenance cost increased.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and since the drain generated from the combustion exhaust gas does not stay in the gas passage,
It is an object of the present invention to provide a method for operating a regenerative burner furnace that does not cause harmful effects due to drainage.

[0013]

A method of operating a regenerative burner furnace according to the present invention is configured such that two combustion burners are used as a pair and combustion and exhaust gas exhaust gas are alternately shared, and the combustion is generated by one combustion burner. The generated combustion exhaust gas is exhausted through the gas passage of the other combustion burner, the sensible heat of the combustion exhaust gas is stored in the heat storage body arranged in the gas passage of the combustion burner, and the combustion air is supplied to the gas passage during combustion. In operation of a regenerative burner furnace equipped with at least one pair of regenerative burners configured to preheat combustion air through the regenerator, combustion exhaust gas temperature and heat storage of the regenerator outlet side of the regenerative burner performing heat storage After measuring the elapsed time from the start, the elapsed time when the measured combustion exhaust gas temperature reaches the preset drain extinction temperature is If it is less than the burner switching set time that has been set, the combustion and exhaust of the burner are switched when the burner switching setting time elapses.If it is more than the burner switching setting time, the combustion of the burner is immediately burned. Operating method of the heat storage type burner furnace characterized by switching the exhaust gas, and, in place of the above switching method, when the elapsed time reaches a preset burner switching setting time, of the measured combustion exhaust gas When the temperature reaches the preset drain extinction set temperature, the combustion and exhaust for the burner are switched immediately, and when not reached, the combustion and exhaust for the burner are switched when the temperature is reached. This is the operation method of the regenerative burner furnace.

Further, the drain extinction set temperature is set to be 50 to 100 ° C. higher than the dew point of the combustion exhaust gas.

When the temperature of the combustion exhaust gas on the outlet side of the heat storage body is changed with time when the furnace is started up, the tendency shown in the graph of FIG. 4 is shown. In this figure, the horizontal axis represents the elapsed time and the vertical axis represents the combustion exhaust gas temperature on the heat storage body outlet side. Also, the symbols shown in the figure indicate the combustion exhaust gas discharge time zone at the time of starting the heating furnace, is the first discharge time zone of the same burner, and is the second discharge time zone. Indicates. The dotted curve shows the change over time in the combustion exhaust gas temperature of the other burner paired.

The combustion exhaust gas temperature at the heat storage outlet side at the time of starting the heating furnace is approximately 30 ° C. at the beginning (that is, the temperature close to room temperature before the combustion exhaust gas does not pass), as shown in the time zone of. At such a low temperature, the temperature of the combustion exhaust gas is lower than the dew point of the contained water, so that the water condenses in the pipe and becomes drain.

The combustion exhaust gas temperature rises with the passage of time. For example, when M gas (mixed gas of blast furnace gas and coke oven gas) is used as the fuel, the drainage evaporates and disappears when the temperature of the combustion exhaust gas reaches 160 ° C. Therefore, if combustion is switched to at this point, the probability that the drain will be blown into the furnace together with the combustion air is reduced.

According to the present invention, the temperature of the combustion exhaust gas is further increased in consideration of the possibility that the temperature may be lowered and the drain may be generated again when the combustion exhaust gas is closer to the discharge port than the temperature measurement location. The exhaust of the combustion exhaust gas is continued until then, and when the temperature reaches a predetermined temperature, the exhaust of the combustion exhaust gas is stopped. In the present invention, this predetermined temperature is called the drain extinction set temperature.

In the time zone of, the elapsed time A ₁ when the temperature of the combustion exhaust gas reaches the drain extinction set temperature is the burner switching set time preset as the burner switching pitch when the steady operation state is entered. Since it becomes longer than T, the emission of combustion exhaust gas is stopped at this point and the paired burner and combustion / exhaust gas are switched.

In the time zone of, since the inside of the furnace is heated in the time zone of, the temperature of the combustion exhaust gas is high from the start of combustion exhaust gas discharge, and the time A ₂ until the drain extinction set temperature is reached is Shorter than the obi.

In the n-th combustion exhaust gas discharge time zone,
If the time to reach the drain disappearance set temperature of the combustion exhaust gas and A _n, the value of A _n is reduced every time the number of switching increases. Then, it becomes equal to the burner switch setting time T final, until a zero value of (A _n -T), and continues the discharging time flue gas A _n. In FIG. 4, A ₃ = T in the time zone of, and A _n <T after the time zone of.

When the value of (A _n -T) becomes a negative value, _if the combustion is switched to within the time of A _n , the burner switching pitch becomes too fast. When it becomes a state, that is, when it becomes possible to operate in a steady state, the burner switching set time T
Switch every time.

At the start of combustion exhaust gas discharge, if the combustion exhaust gas temperature is equal to or higher than the drain extinction set temperature, the above _An is 0. Therefore, in such a state, the burner switching set time T may be used for switching.

Further, when resuming after the lowered furnace interrupts the furnace operation during operation temperature also the value as long as it is positive, the discharge time flue gas A _n of (A _n -T) It should be continued.

Instead of such a control method, when the elapsed time from the start of heat storage reaches the burner switching set time,
It is determined whether the temperature of the combustion exhaust gas is equal to or higher than the drain extinction set temperature, and if it is equal to or higher than the drain extinction set temperature, the combustion burner and heat storage are immediately switched, and the temperature of the combustion exhaust gas does not reach the drain extinction set temperature. In this case, the same effect can be obtained by switching between combustion and heat storage of the burner when the drain extinction set temperature is reached.

As a result of various experiments, it was found that the drain extinction set temperature should be set 50 to 100 ° C. higher than the dew point of the combustion exhaust gas (the temperature at which dew condensation starts in the process of cooling the combustion exhaust gas). It was That is, if the temperature is set lower than 50 ° C, the temperature of the combustion exhaust gas may be decreased in the downstream side, and drain may be regenerated. If the temperature is set higher than 100 ° C, the burner switching pitch at the time of starting the furnace becomes long. This is because it becomes an unfavorable local heating state.

Therefore, when M gas is used as the fuel, the drain extinction set temperature is 160 to 100 ° C.
The temperature may be set to 210 ° C., that is, 210 to 260 ° C.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION A method for operating a regenerative burner furnace which is a first embodiment of the present invention will be described with reference to FIG.
FIG. 1 (a) is an explanatory view showing the equipment configuration of this heat storage type burner furnace, and FIG. 1 (b) is a block diagram showing the processing procedure when performing burner switching.

In this operating method, the gas passages 26a and the gas passages 26a of the regenerative burners 22a and 22b, which are provided to face the side walls 21a and 21b on both sides of the regenerative burner furnace 21 and are provided with the regenerators 23a and 23b, respectively. Thermometers 1a and 1b for measuring the temperature of the combustion exhaust gas are provided on the outlet sides of the heat storage bodies 23a and 23b of 26b.

Further, the elapsed time T from when the combustion exhaust gas starts to pass through the respective gas passages 26a or 26b in conjunction with the opening / closing commands of the fuel cutoff valves 24a and 24b of the respective regenerative burners 22a and 22b.
The timers 2a and 2b for measuring are provided.

The time-dependent change of the combustion exhaust gas temperature on the outlet side of the heat storage bodies 23a and 23b from the start-up of the heat storage type burner furnace is grasped.

The temperature signal t measured by the thermometer 1a or 1b is the drain extinction set temperature t in advance.
₀ is sent to the set temperature difference calculator 3, (t−t ₀ ).
Is calculated.

On the other hand, the time signal τ of the timer 2a or 2b is sent to the time difference calculator 4 in which the burner switching set time τ ₀ is set in advance, and the value of (τ-τ ₀ ) is calculated.

Then, the value of the temperature difference (t-t ₀ ) and the value of the time difference (τ-τ ₀ ) are sent to the burner switching judging device 5,
When the value of (t−t ₀ ) becomes 0 and the value of (τ−τ ₀ ) is zero or positive, a combustion switching command is immediately issued to the combustion switching controller 6 and the fuel cutoff valve 24a, 24
b and the switching valve 25 are operated to switch the combustion. Also, when the value of (t−t ₀ ) becomes 0,
When the value of (τ-τ ₀ ) is negative, the combustion is continued as it is, and when the value of (τ-τ ₀ ) becomes 0, a combustion switching command is issued to the combustion switching controller 6. The fuel cutoff valves 24a and 24b and the switching valve 25 are operated to switch combustion.

Alternatively, when the value of (τ−τ ₀ ) becomes 0 and the value of (t−t ₀ ) is zero or positive, a combustion switching command is immediately issued to the combustion switching controller 6, Combustion is switched by operating the fuel cutoff valves 24a and 24b and the switching valve 25. When the value of (τ−τ ₀ ) becomes 0, when the value of (t−t ₀ ) is negative,
When the combustion is continued as it is and the value of (τ-τ ₀ ) becomes 0, a combustion switching command is issued to the combustion switching controller 6, and the fuel cutoff valves 24a, 24b and the switching valve 25 are output.
Is operated to switch the combustion.

That is, the combustion switching is t−t ₀ ≧ 0,
And it is performed when the condition of τ−τ ₀ ≧ 0 is satisfied.

In addition, the operating condition of each valve at the time of switching combustion,
As shown in FIG. 1, the regenerative burner 22a burns,
When the combustion type exhaust gas is being discharged by the thermal type burner 22b, combustion is performed by the thermal storage type burner 22b, and the thermal storage type burner 2
The following is a description of the case where combustion switching is performed so that combustion exhaust gas is discharged at 2a.

(1) Before switching combustion, the fuel cutoff valve 24a
Is open and the fuel cutoff valve 24b is closed, the switching valve 25 is in a state of supplying combustion air to the regenerative burner 22a through the gas passage 26a and discharging combustion exhaust gas through the gas passage 26b of the regenerative burner 22b. There is.

(2) Fuel cutoff valve 24a after combustion switching
Is closed and the charge shutoff valve 24b is open, the switching valve 25 is in a state of supplying combustion air to the regenerative burner 22b through the gas passage 26b and discharging combustion exhaust gas through the gas passage 26a of the regenerative burner 22a. There is.

As a matter of course, in the opposite case, the state of the above item (2) may be changed to the state of the item (1).

When the combustion is switched in this way, the temperature inside the furnace is low when the heating furnace is started up, so the temperature of the combustion exhaust gas at the outlet side of the heat storage body 23a or 23b can be easily set to the drain extinction set temperature t. _Since it does not reach ₀ , the time τ until the burner is switched becomes longer than the burner switching set time τ ₀ .

However, by continuing the combustion, the temperature on the heat storage body outlet side gradually rises, and finally the burner is switched at every burner switching set time τ ₀ .

The method of operating the heating furnace of the present invention can be applied to the case where the operation of the heating furnace is interrupted and the operation is restarted after the temperature inside the furnace is lowered, and the heat storage bodies 23a and 23b are used to interrupt the operation. When the temperature of the exhaust gas on the outlet side of the exhaust gas is below the drain extinction set temperature t ₀ , the burner switching time is set to be longer than the burner switching set time τ ₀ until the combustion exhaust gas temperature rises sufficiently as described above. It should be long enough to operate.

In the operation method of the heat storage type burner furnace as described above, as a matter of course, since the drain does not remain in the gas passages 26a and 26b, the above-mentioned harmful effects by the drain do not occur. .

Next, a method of operating the regenerative burner furnace according to the second embodiment of the present invention will be described with reference to FIG.

In the heat storage type burner furnace 31 shown in FIG. 2, a plurality of heat storage type burners are arranged on both sides of the furnace wall so as to face each other, and these are set to A (three burners) and B (burner 3).
Group), C (4 burners) and D (4 burners). The A and C groups have common combustion air and combustion exhaust gas pipes, and the B and D groups have the same structure. When starting up the furnace, A-B-C-D-A
-B-C-D -... are burned in order. And the relationship between A group and B group is A
When the group B is burning, the exhaust gas of the flue gas is discharged from the group B, and when the group B is burning,
The relationship is to discharge flue gas as a group.

The relationship between the C group and the D group is
When the C group is burning, the D group emits exhaust gas, and when the D group is burning,
The relationship will be to discharge combustion exhaust gas in Group C.

Explaining the relationship between the A group and the B group, a thermometer 11a for measuring the temperature of the combustion exhaust gas is provided on the outlet side of the heat storage body 33a attached to the burner 32a of the A group, and a burner 32b of the B group. A thermometer 11b for measuring the temperature of the combustion exhaust gas is provided on the outlet side of the heat storage body 33b attached to the.

When burning in the burner 32a of the A group, the fuel cutoff valve 3 for supplying the fuel to the burner 32a.
4a is open and fuel is being supplied. Then, the combustion air cutoff valve 35a is opened, the combustion exhaust gas cutoff valve 36a is closed, and the combustion air is supplied.

On the other hand, in the burner 32b of group B, the fuel cutoff valve 34b is closed and the supply of fuel is stopped. Then, the combustion air cutoff valve 35b is closed and the combustion exhaust gas cutoff valve 36b is opened, so that the combustion exhaust gas is discharged.

In such a state, the temperature of the combustion exhaust gas is measured by the thermometer 11b provided on the outlet side of the heat storage body 33b.

Further, when the burners 32b of the B group are burning, the open / closed states of the valves are the opposite of the above.

Since there are many burners in this case, the average value of the measured combustion exhaust gas temperature within the zone is compared with the drain extinction set temperature set for each zone. By using the average value, even if the combustion exhaust gas temperature on the outlet side of the heat storage body in the zone varies, the drain generation / evaporation conditions can be correctly evaluated and optimal switching can be performed.

In this embodiment, a part of the combustion exhaust gas piping is shared, and switching is performed as described above. Therefore, when Group A and Group B are performing combustion and combustion exhaust gas discharge, C, The combustion exhaust gas pipes of Group D are heated. When the C and D groups start burning, the temperature drop on the downstream side of the combustion exhaust gas is mitigated,
The drain extinction set temperature can be set lower (that is, near the dew point of combustion exhaust gas + 50 ° C). Therefore, the switching time of each group is shortened, there is an effect that the inside of the furnace is uniformly heated without being locally heated for a long time.

Further, in this embodiment, the combustion switching timing is determined by comparing the elapsed time from the start of combustion exhaust gas discharge with the burner switching set time set for each zone.

Since the burner switching setting time affects the combustion efficiency, there is an effect that the optimum value can be set for each zone when the rating and the number of burners are different for each zone.

[0057]

The present invention has the following effects. (1) Since the drain is not sprayed into the furnace, the combustion flame temperature does not decrease, and the temperature rising rate of the furnace increases. (2) Since the drain is not sprayed into the furnace, the object to be heated is suppressed from being oxidized and the quality of the product is improved. (3) Since the accumulation of drain in the pipe is reduced, the corrosion of the pipe is reduced and the maintenance cost becomes easier. (4) Since the generation of drain is suppressed, the combustion becomes stable under the condition where the furnace temperature is low.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an operation method of a heat storage type burner furnace which is a first embodiment of the present invention, (a) is an explanatory view showing an equipment configuration of the heat storage type burner furnace, and (b) is a burner. It is a block diagram which shows the process sequence at the time of switching.

FIG. 2 is an explanatory diagram of a method of operating a regenerative burner furnace that is a second embodiment of the present invention.

FIG. 3 is an explanatory view of a method of operating a conventional regenerative burner furnace.

FIG. 4 is a graph showing a change over time in the temperature of the combustion exhaust gas on the heat storage body outlet side from the time when exhaust gas discharge is started.

[Explanation of symbols]

 1a, 1b Thermometer 2a, 2b Timer 3 Temperature difference calculator 4 Time difference calculator 5 Burner switching judgment device 6 Combustion switching controller 11a, 11b Thermometer

Claims (3)

[Claims] 1. Combustion and combustion exhaust gas exhaust are alternately shared by two combustion burners as a pair, and combustion exhaust gas generated by combustion by one combustion burner is exhausted through a gas passage of the other combustion burner to perform combustion. While storing the sensible heat of the exhaust gas in the heat storage body arranged in the gas passage of the combustion burner, at the time of combustion, supplying combustion air to the gas passage,
In operation of a regenerative burner furnace equipped with at least one pair of regenerative burners for preheating combustion air through the regenerator, combustion exhaust gas temperature at the regenerator outlet side of the regenerative burner performing heat storage and start of heat storage. Measure the elapsed time from the time, and if the elapsed time when the measured combustion exhaust gas temperature reaches the preset drain extinction set temperature is less than the preset burner switching set time, A method for operating a regenerative burner furnace characterized by switching combustion and exhaust to the burner when the set switching time has elapsed, and immediately switching combustion and exhaust to the burner when the set switching time is exceeded. 2. Combustion and combustion exhaust gas exhaust are alternately shared by using two combustion burners as a pair, and combustion exhaust gas generated by combustion by one combustion burner is exhausted through a gas passage of the other combustion burner to perform combustion. While storing the sensible heat of the exhaust gas in the heat storage body arranged in the gas passage of the combustion burner, at the time of combustion, supplying combustion air to the gas passage,
In operation of a regenerative burner furnace equipped with at least one pair of regenerative burners for preheating combustion air through the regenerator, combustion exhaust gas temperature at the regenerator outlet side of the regenerative burner performing heat storage and start of heat storage. When the elapsed time has been measured and the elapsed time has reached the preset burner switching set time, the measured combustion exhaust gas temperature has reached the preset drain extinction set temperature. Is a method for operating a regenerative burner furnace characterized by immediately switching between combustion and exhaust for the burner, and when it has not arrived, switching between combustion and exhaust for the burner when it has arrived. 3. The method for operating a regenerative burner furnace according to claim 1, wherein the drain extinction set temperature is set to be 50 to 100 ° C. higher than the dew point of the combustion exhaust gas.