JPH0774693B2 - Combustion control method for regenerative burner system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control method for a regenerative burner system that operates two pairs of burner systems.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 7 and 8, there are known burners applicable to the heat storage type burner system. In the burner 100, a first fuel nozzle 102 is formed in the center of a burner body 101, and a plurality of air nozzles 103 are formed around the first fuel nozzle 102. A plurality of second nozzles are provided around the air nozzle 103.
A fuel nozzle 104 is formed. Further, in the burner 100, the first fuel nozzle 102 inside when the furnace temperature is low.
The fuel gas is further injected, and is rapidly mixed with the combustion air injected from the air nozzle 103 and burned. When the blast furnace temperature is high, the fuel gas is injected from the second fuel nozzle 104 located outside the air nozzle 103, and the fuel gas is mixed with the combustion air injected from the air nozzle 103 and burned. Therefore, the combustion at low furnace temperature becomes stable, and
Generation of nitrogen oxides at the time of blast furnace temperature is suppressed.

[0003]

However, in the above burner 100, in order to switch the combustion state of the fuel,
Since the two types of fuel injection nozzles 102 and 104 are formed in the main body 101, there is a problem that the burner 100, the fuel piping, and the switching control become complicated. Further, since the first fuel nozzle 102, which is shut off at the time of the blast furnace temperature, passes through the side portion of the air nozzle 103, there is a problem that the preheating of the combustion air passing through the air nozzle 103 heats it and carbonizes the residual fuel. It was

[0004]

The present invention has been made to solve the above problems, and a combustion control method for a heat storage type burner system according to the present invention alternately supplies combustion air and exhausts combustion exhaust gas. Two flow paths for performing the above, a variable capacity fuel injection nozzle arranged in the middle of these flow paths, and an integrated burner composed of a central air path, and connecting pipes respectively connected to the flow paths, Breathable heat accumulators respectively housed in the connecting pipes, an air on-off valve and an exhaust gas on-off valve connected to this heat accumulator, an air supply means and an exhaust gas exhaust connected to these air on-off valves and exhaust gas on-off valves In a method of operating a pair of two burner systems each comprising a means, a fuel opening / closing valve for one of the burner systems, with the fuel injection nozzle set to a fuel flow rate exceeding a rating. A combustion method in which the air opening / closing valve is opened and the exhaust gas opening / closing valve is closed, and for the other burner system, the exhaust gas opening / closing valve is opened and the fuel opening / closing valve and the air opening / closing valve are closed. With the injection nozzle set to a fuel flow rate below the rated value, the fuel opening / closing valve is opened, the air opening / closing valve communicating with one of the regenerators is opened, and the exhaust gas opening / closing valve communicating with the regenerator is closed, and the other The combustion method in which the exhaust gas on-off valve that communicates with the regenerator and the air on-off valve that communicates with the regenerator are closed alternately for each of the above two sets of burner systems is arbitrarily selected.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a burner system. In this burner system Bs, a main body 2 of a regenerative burner 1 is made of a known refractory material, a central air passage 3 is provided in the center of the main body 2, and a first air flow is provided above and below the central air passage 3. Passage 4a, second air passage 4b
And connecting pipes 5, 6a, 6b are connected to the rear ends of these air flow paths 3, 4a, 4b, respectively. A fuel nozzle 7 is inserted through the central air passage 3 and the connecting pipe 5 so as to penetrate the rear end of the connecting pipe 5. Further, regenerators 8a and 8b accommodating heat storage media 9a and 9b such as ceramic pellets are connected to the connecting pipes 6a and 6b communicating with the air flow paths 4a and 4b, respectively.

As shown in FIGS. 3 and 4, the fuel nozzle 7 has a ring-shaped front wall 12 and a rear wall 12 with inner peripheral walls 11 protruding inward from the front and rear of an outer cylinder 10 made of a cylindrical body. 1
3 by means of which a front opening 14 and a rear opening 15 are provided.
Are formed, and the first fuel injection holes 16 that extend obliquely outward are formed in the front wall 12 at predetermined intervals.

The inner cylinder 19 is a cylindrical body having a ring-shaped stopper wall 20 formed by projecting its front end outwardly.
It is housed coaxially with the inside of the rear wall of the rear wall 1
The fuel flow passage 21 is fixed between the stopper wall 20 and the front wall 12 and has a predetermined length.

The switching valve 22 includes a shaft 23, a ring-shaped flange portion 24 having a tip end portion of the shaft 23 protruding outwardly and having an outer diameter substantially the same as that of the opening portion 14, and the flange portion 24. A sleeve 25 having an outer peripheral end portion extended rearward, and a ring-shaped seal portion 26 having a rear outer peripheral surface of the sleeve 25 protruding outward. The flange portion 24 has a first fuel injection hole 16 The second fuel injection holes 27 each having a small diameter are formed at predetermined intervals.

The switching valve 22 has an opening 15 in the rear wall 13.
Insert the shaft 23 into the inner cylinder 19 via the sleeve 2
5, the rear end of the seal member 5 faces the stopper wall 20, the seal portion 26 is positioned in the fuel flow path 21, and the seal portion 26 is moved to the first position as shown in FIG.
It is possible to move back and forth between the forward position where the fuel injection hole 16 is closed and the backward position where the rear end of the sleeve 25 contacts the stopper wall 20, as shown in FIG. A seal member 17 seals between the shaft 23 and the opening 15.

In the combustion nozzle 7 having the above structure, the switching valve 22
3 in the forward position shown in FIG. 3, the sleeve 25 is separated from the stopper wall 20 to open the fuel flow path 21, and the seal portion 26 abuts on the rear surface of the front wall 12 so that the first fuel injection hole 16
To close. Therefore, the supplied fuel gas is transported to the inner space of the sleeve 25 via the fuel flow path 21,
It is injected straight through the second fuel injection hole 27. Further, when the switching valve 22 is in the retracted position shown in FIG. 4, the seal portion 26 is separated from the front wall 12, and the rear end of the sleeve 25 contacts the stopper wall 20 to close the fuel flow passage 21. Therefore, the fuel gas supplied from the fuel gas supply pipe 18 moves forward in the annular space formed between the outer cylinder 10 and the inner cylinder 19, passes through the outside of the seal portion 26, and reaches the first position.
The fuel is injected obliquely outward from the fuel injection hole 16.

A combustion system including the above two sets of burner systems will be described with reference to FIGS. In this combustion system, the burner system Bs,
A plurality of pairs of Bs' are attached as two pairs. In the burner 1 of the burner system Bs, the fuel supply pipe 18 of the fuel nozzle 7 is connected to a fuel supply source (not shown) via the fuel control valve 31, and the connecting pipe 5 leading to the central air passage 3 is connected via the air control valve 32. Is connected to an air supply fan 35 that is an air supply means. In addition, the air flow paths 4a and 4b
Connecting pipes 6a and 6b are branched into two, one of which is connected to the air supply fan 35 through the air control valves 33a and 33b, and the other of which is an exhaust gas discharging means through the exhaust gas control valves 34a and 34b. It is connected to the exhaust fan 36. The same applies to the burner system Bs ′, and the same reference numerals are used for the same members and the description thereof is omitted.

In the above combustion system, the rated operation mode in which the fuel nozzle 7 injects and burns a rated amount or less than the rated amount of fuel gas, and the fuel nozzle 7 injects and burns twice the rated amount of fuel gas. Two types of operation modes, the non-rated operation mode, can be arbitrarily selected. The rated operation mode is a combustion mode in a blast furnace temperature state in which the temperature is equal to or higher than a predetermined temperature, for example, the ignition temperature of fuel gas.
On the other hand, the non-rated operation mode is a low furnace temperature state below the predetermined temperature or a combustion mode when starting up the furnace.

In the rated operation mode, each control valve is alternately set to a first operation state shown in Table 1 and a second operation state shown in Table 2 below at predetermined time intervals (in the table, ◯).
Indicates the open state of the control valve, and x indicates the closed state of the control valve. ). Further, in the fuel nozzle 7, the switching valve 22 is set to the forward position and the fuel is ejected from the small-diameter second fuel ejection hole 27.

[0014]

[Table 1]

[0015]

[Table 2]

That is, in the first operation state in the rated operation mode, the fuel control valves 31, 31 'and the air control valves 32, 32' are opened, and the burner 1, 1'is supplied with fuel gas, and Combustion air is supplied to the central air passages 3, 3 '. For the burner 1, the air control valve 3
3a and the exhaust gas control valve 34b are opened, the air control valve 33b and the exhaust gas control valve 34a are closed, the combustion air is supplied from the air supply fan 35 to the first air passage 4a, and the combustion air is mixed and burned with the fuel gas. At the same time, the exhaust fan 36 sucks and exhausts the exhaust gas in the furnace 30 through the second air flow path 4b, and the heat of the exhaust gas is stored in the heat storage device 8b. Regarding the other burner 1 ', the air control valve 33b' and the exhaust gas control valve 34a 'are opened, and the air control valve 33a' and the exhaust gas control valve 34 are opened.
b'is closed, combustion air is supplied to the second air flow path 4b ', and this combustion air is mixed and burned with fuel gas, and
The exhaust fan 36 allows the furnace 3 to pass through the first air flow path 4a '.
The exhaust gas in 0 is sucked and exhausted, and the heat of the exhaust gas is stored in the heat accumulator 8
It is stored in a '.

In the second operating state, the fuel control valves 31, 31 'and the air control valves 32, 3 are the same as in the first operating state.
2'is held in an open state, and fuel gas and combustion air are supplied to the burners 1, 1 '. Regarding the burner 1, the air control valve 33b and the exhaust gas control valve 34a are opened, the air control valve 33a and the exhaust gas control valve 34b are closed, and the air supply fan 35 is installed.
The combustion air supplied from the above is preheated by the heat stored in the heat accumulator 8b during the first operating state, and is then mixed and burned with the fuel gas injected from the second air flow path 4b and exhausted. The exhaust gas in the furnace 30 is sucked and exhausted by the fan 36 via the first air flow path 4a, and the heat of the exhaust gas is stored in the heat storage device 8a. Regarding the other burner 1 ′, the air control valve 33a ′ and the exhaust gas control valve 34b ′ are opened, the air control valve 33b ′ and the exhaust gas control valve 34a ′ are closed, and the combustion air supplied by the air supply fan 35 is After being preheated by the heat stored in the heat storage device 8a ′ during the first operating state, the fuel is injected from the first air flow path 4a ′ and mixed and burned with the fuel gas, and the exhaust fan 36 causes the second air flow. The exhaust gas in the furnace 30 is sucked and exhausted through the path 4b ', and the heat of the exhaust gas is stored in the heat storage device 8b'. In addition, the heat storage device 8
The heat stored in a and 8b 'is used for preheating the combustion air in the first operating state. Further, in the rated combustion state set by the blast furnace temperature, the mixture of air and fuel becomes gentle, so that nitrogen oxides can be reduced.

In the non-rated operating mode, each control valve is alternately set to a third operating state shown in Table 3 below and a fourth operating state shown in Table 4 below every predetermined time (in the table,
◯ indicates the control valve open state, and x indicates the control valve closed state. ).
Further, the fuel nozzle 7 sets the switching valve 22 to the retracted position,
The state is set such that the fuel gas is ejected from the large-diameter first fuel ejection hole 16.

[0019]

[Table 3]

[0020]

[Table 4]

That is, in the third operating state in the non-rated operating mode, the burner 1 has the fuel control valve 3
1 and the air control valve 32 are opened to inject fuel gas and combustion air into the furnace 30. In addition, the air control valves 33a and 33b
Are opened together, the exhaust gas control valves 34a, 34b are closed together, and the combustion air injected from the air flow paths 4a, 4b is mixed and burned with the fuel gas. On the other hand, for the burner 1 ', the fuel control valve 31' is closed and the air control valve 33a ',
33b 'is closed and the exhaust gas control valve 34a',
34b 'is opened to set the exhaust gas exhaust mode, and the exhaust gas in the furnace 30 is sucked and exhausted by the exhaust fan 36 through the air flow paths 4a', 4b '. Further, the heat of the exhaust gas is recovered by the heat accumulators 8a 'and 8b' and is used for preheating the combustion air in the next fourth operating state. The combustion air control valve 3
2'will always open regardless of mode to facilitate cooling of the fuel nozzle 7.

Next, in the fourth operating state in the non-rated operating mode, the fuel control valve 31 of the burner 1 is closed,
The air control valves 33a and 33b are closed, the exhaust gas control valves 34a and 34b are opened to set the exhaust gas exhaust mode, and the exhaust gas in the furnace 30 is sucked and exhausted to the exhaust fan 36 through the air flow paths 4a and 4b. . Further, the heat of the exhaust gas is recovered by the heat accumulators 8a and 8b and is used for preheating the combustion air in the next third operating state. On the other hand, in the burner 1 ', the fuel control valve 31' and the combustion air control valve 32 'are opened to inject the fuel gas and the combustion air into the furnace 30.
In addition, the air control valves 33a 'and 33b' are both opened, the exhaust gas control valves 34a 'and 34b' are both closed, and the combustion air supplied from the air supply fan 35 is stored in the heat accumulators 8a 'and 8b'.
Is preheated when passing through, and the preheated combustion air is injected from the air flow paths 4a ', 4b' and mixed and burned with the fuel gas.

In the non-rated operation mode, a larger amount of fuel (twice the fuel in the present embodiment) is injected as compared with the rated operation mode, but the combustion air flowing on both sides (upper and lower) of the fuel efficiently. Since they are mixed, a stable complete combustion state is obtained.

In the above description, in the non-rated operation mode,
Although the third operating state and the fourth operating state are alternately performed, when the temperature distribution in the furnace is changed depending on the condition of the processing material, the third or fourth operating state and the first or second operating state are changed. You may make it combine and drive suitably. By doing so, the flexibility of the heating pattern is improved.

[0025]

As is apparent from the above description, according to the combustion control method of the regenerative burner system of the present invention,
Without providing two fuel nozzles for low furnace temperature and blast furnace temperature for each burner, stable complete combustion at low furnace temperature can be achieved and generation of nitrogen oxides at blast furnace temperature can be suppressed.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a heat storage type burner.

FIG. 2 is a front view of a heat storage type burner.

FIG. 3 is a vertical cross-sectional view of a fuel nozzle at a shaft advancing position.

FIG. 4 is a vertical cross-sectional view of a fuel nozzle at a shaft retracted position.

FIG. 5 is a circuit diagram of a combustion system showing a rated operation mode.

FIG. 6 is a circuit diagram of a combustion system showing an unrated operation mode.

FIG. 7 is a front view of a conventional burner.

8 is a sectional view of the burner shown in FIG. 7 taken along line VIII-VIII.

[Explanation of symbols]

1 ... Burner, 2 ... Burner body, 3 ... Central air passage, 4a,
4b ... Air flow path, 5, 6a, 6b ... Connection pipe, 7 ... Fuel nozzle, 8a, 8b ... Heat storage device, 9a, 9b ... Heat storage medium, 3
0 ... Furnace, 31 ... Fuel control valve, 32, 33a. 33b ... Combustion air control valve, 34a. 34b ... Exhaust gas control valve, Bs,
Bs' ... Burner system.

Claims (1)

[Claims] 1. A flow passage for alternately supplying combustion air and exhausting combustion exhaust gas, a variable capacity fuel injection nozzle arranged in the middle of these flow passages, and a central air passage. Body burner, connecting pipes respectively connected to the flow paths, breathable heat storage devices respectively accommodated in the connection pipes, an air on-off valve and an exhaust gas on-off valve connected to this heat storage device, and these In a method of operating a pair of burner systems each consisting of an air supply means and an exhaust gas discharge means connected to an air opening / closing valve and an exhaust gas opening / closing valve, in a state where the fuel injection nozzle is set to a fuel flow rate exceeding a rating. , Open the fuel on-off valve and air on-off valve for one burner system and close the exhaust gas on-off valve, and open the exhaust on-off valve for the other burner system and open the fuel on-off valve and air Combustion method in which the combustion state in which the valve is closed is alternated every predetermined time, and with the fuel injection nozzle set to a fuel flow rate below the rated value, the fuel on-off valve is opened and communicated with one of the regenerators. The mode in which the air on-off valve is opened and the exhaust gas on-off valve communicating with the heat storage device is closed, and the mode in which the exhaust gas on-off valve communicating with the other heat storage device is opened and the air on-off valve communicating with the heat storage device is closed A combustion control method for a heat storage type burner system, characterized in that a combustion method performed alternately for each burner system is arbitrarily selected.