JP2002286204A - Reduction combustion mechanism and reduction combustion method in regenerative burner system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem with prior art that although in a regenerative burner system, for ensuring non-oxidization heating for an article to be heated and low NOx reduction combustion is performed in a furnace, and complete combustion air is introduced into a burner on the side of exhaustion, and unburnt components are completely combusted, a predetermined amount of the complete combustion air is supplied at all times, and hence stable reduction combustion is not necessarily obtained in an actual operation. SOLUTION: In the present invention, a regenerative burner system is adapted such that a pair of burners 3a, 3b including heat storage sections 2a, 2b are provided in a furnace body 1, to which burners an oxidizing agent supply passage 6 and an exhaust passage 9 both including a changeover valve are connected, which passages are communicated with the inside of the furnace 11 through space sections 10a, 10b constructed on the side of the furnace body from the heat storage section. In the system, the space sections of the respective burners are communicated to a communication passage 14 to propose a reduction combustion mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reducing combustion mechanism and a reducing combustion method in a regenerative burner system.

[0002]

2. Description of the Related Art A regenerative burner system includes:
High efficiency combustion is performed by alternately burning a pair of burners having a heat storage section and recovering exhaust heat of the combustion exhaust gas. In such a regenerative burner system, the object to be heated in the furnace is completely removed. Oxidation heating and low NOx
In the furnace, reduction combustion is performed by combustion air having a stoichiometric ratio of 1 or less supplied together with fuel from a combustion side burner in the furnace, and a space is provided upstream of the heat storage section of the exhaust side burner. There has been proposed a reduction combustion method in which air for complete combustion is introduced to completely burn unburned components.
(See, for example, JP-A-7-133908)

Referring to FIG. 4, such a conventional reduction combustion method will be described. Reference numeral a denotes a furnace body, and b and b 'are a pair of burners. These burners have a heat storage section filled with a heat storage material. c and c 'are configured. The burners b and b 'are connected to combustion air supply paths d and d' each having a switching valve (not shown) and exhaust paths e and e ', respectively. Spatial parts f and f 'formed on a side
The fuel is supplied from a fuel supply pipe (not shown) via the. These space portions f, f 'are provided with complete combustion air introduction portions g, g', from which the complete combustion air is supplied.

In the above configuration, the switching valves of the combustion air supply path d of the right burner b and the exhaust path e 'of the left burner b' are opened in FIG. The combustion air is supplied from the combustion air supply path d to the burner b on the right side in the drawing, and the fuel is supplied from the fuel supply pipe for combustion, and the combustion gas in the furnace burns in the space f of the other burner b '. ′, Is exhausted through the heat storage section c ′ and through the exhaust path e ′. At this time, in the furnace, reduction combustion is performed by combustion air having a stoichiometric ratio of 1 or less supplied together with fuel from the burner b on the combustion side, and the space f 'of the burner b' on the exhaust side.
The unburned components that have reached are completely burned by the complete combustion air introduced from the complete combustion air introduction part g '.

On the other hand, when the switching valves of the combustion air supply path d 'of the left burner b' and the exhaust path e of the right burner b are opened, the left burner is opposite to the state of FIG. b 'burns, and the combustion gas in the furnace is exhausted through the right burner b.

In the above-described alternating combustion, the supply of the combustion air through the combustion air supply paths d and d 'and the supply of the fuel through the fuel supply pipe are respectively switched by the switching valve. The switching using a switching valve or the like is not performed, and a constant amount is always supplied from the complete combustion air introduction sections g and g '.

[0007]

In such a reduction combustion method, complete combustion air is supplied into the furnace even during the switching time (about 1 to 2 seconds) of each switching valve at the time of combustion switching of the burner. In an actual industrial furnace, temperature control is performed during operation, and the output of the burner changes according to this temperature control, so that stable reduction combustion cannot be obtained in actual operation. For example, temperature control is time proportional control (ON-O
In the case of FF control), as in the above switching time, complete combustion air is supplied into the furnace even when the burner is stopped in this control, so that the reducibility is significantly impaired at this point. In the case where the temperature control is position proportional control (flow rate control) in which the flow rates of fuel and air are changed in accordance with a control signal of a temperature controller, a certain point, for example, complete combustion air having a flow rate adjusted at the time of maximum combustion is supplied. When always supplied, the complete combustion air supplied to the exhaust side burner does not contribute to combustion in the furnace, but the complete combustion air supplied to the combustion side burner contributes to combustion in the furnace. If the combustion amount is lower than the maximum combustion time, the proportion of the air for complete combustion relatively increases, and there is a possibility that reduction combustion is not performed in the furnace. Therefore, an object of the present invention is to solve such a problem.

[0008]

In order to solve the above-mentioned problems, according to the present invention, a pair of burners having a heat storage section is provided in a furnace body, and each burner is provided with an oxidizing agent provided with a switching valve. In the regenerative burner system, which connects the path and the exhaust path and communicates with the inside of the furnace through a space configured on the furnace body side rather than the heat storage section, the space sections of each burner are connected by a communication path. A reduction combustion mechanism with a communicating configuration is proposed.

Further, the present invention proposes to provide a flow control mechanism in the communication path in the above configuration.

In the present invention, it is proposed that the pair of burners is a radiant tube burner connected to an end of the radiant tube.

Further, according to the present invention, in the regenerative burner system having the above-described structure, an oxidant at a flow rate for completely burning fuel is supplied from the oxidant supply path to the burner on the combustion side, and the heat storage of the burner on the combustion side By supplying a part of the oxidizing agent that has reached the space portion through the communication portion to the space portion of the exhaust-side burner through the communication path, the stoichiometric ratio supplied from the combustion-side burner in the furnace is 1 or less. A reduction combustion method is proposed in which an oxidant is used to perform reduction combustion, and an unburned portion reaching a burner on the exhaust side is completely burned by an oxidant supplied through the communication path.

According to the present invention described above, part of the oxidant that has reached the space through the heat storage section of the burner on the combustion side from the oxidant supply path is supplied to the space of the burner on the exhaust side through the communication path. You. As described above, the oxidant supplied to the space of the burner on the exhaust side for complete combustion of the unburned portion is supplied through the oxidant supply path of the burner on the combustion side, so that it is synchronized with the combustion of the burner. Therefore, the oxidizing agent is not supplied into the furnace when the burner stops combustion in the case where the switching time of each switching valve at the time of combustion switching of the burner or the temperature control by the time proportional control is performed.

Further, as described above, the oxidant supplied to the space of the burner on the exhaust side is preheated through the heat storage section of the burner on the combustion side. The size of the reaction region, that is, the space and the like can be reduced.

The ratio of the flow rate of the oxidant supplied from the burner on the combustion side into the furnace and the flow rate of the oxidant supplied to the space of the burner on the exhaust side through the communication path is supplied via the oxidant supply path. Even if the overall flow rate of the oxidizing agent changes, the oxidizing agent is kept substantially constant, so that the reduction combustion can be stably performed even when the temperature control by the position proportional control is performed.

If the flow control mechanism is provided in the communication path, the ratio of the flow rate of the oxidant supplied into the furnace from the burner on the combustion side and the flow rate of the oxidant supplied to the space of the burner on the exhaust side through the communication path Can be appropriately adjusted, and the reduction combustion can be controlled with higher accuracy.

In the case where the burner is a radiant tube burner, since the paired burners are generally arranged at a short distance, the communication path is short and NOx can be easily reduced.

[0017]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a systematic explanatory diagram showing a first embodiment of a regenerative burner system to which the present invention has been applied. Reference numeral 1 denotes a furnace body, and the heat storage units 2a,
A pair of burners 3a and 3b having a pair 2b are provided in the furnace main body 1. An oxidant supply path provided with switching valves 5a and 5b between the burners 3a and 3b and the air supply blower 4, in this case, an air supply path 6 (6a and 6b), is connected to the exhaust blower. The exhaust path 9 (9a, 9b) provided with the switching valves 8a, 8b is connected between the exhaust path 9 and the exhaust path 9. Each of the burners 3a and 3b is provided with spaces 10a and 10b closer to the furnace body 1 than the heat storage units 2a and 2b, and is configured to communicate with the furnace interior 11 through these spaces 10a and 10b. I have. In these spaces 10a and 10b, a fuel supply path 13 having gas switching valves 12a and 12b is provided.
a and 13b are provided. And the burner 3a,
The space portions 10a and 10b of 3b communicate with each other through a communication path 14.

In the above configuration, the switching valves 5b, 8a, and 12b in black in the drawing are closed, and the switching valves 5 not blackened in FIG.
When a, 8b, and 12a are open, combustion air as an oxidant is supplied from the air supply blower 4 to the burner 3a through the air supply paths 6, 6a, and passes through the heat storage unit 2a to the space 10.
to a.

On the other hand, fuel gas is supplied to the space 10a of the burner 3a from the fuel supply path 13a, mixed with the combustion air, and supplied to the furnace 11 for combustion.

At this time, the space 10a passes through the heat storage section 2a.
A part of the combustion air that has reached is supplied to the space 10b of the right burner 3b through the communication path 14 without being mixed with the fuel gas. For this reason, the fuel supply path 13a and the communication path 14 are appropriately arranged such that the fuel gas supplied from the fuel supply path 13a does not flow into the communication path 14.

In the combustion described above, the burner 3
The flow rate of the combustion air supplied to the fuel supply path 13a
Although the flow rate is such that the fuel gas supplied from the fuel tank can be completely burned, the stoichiometric ratio is set to 1 or less when a part passing through the communication path 14 is excluded.

With such a setting, in the furnace 11, the reducing combustion is performed by the combustion air and the fuel gas having the stoichiometric ratio of 1 or less supplied from the burner 3a on the combustion side, and
The unburned portion of the exhaust gas from the furnace 11 to the space 10b of the burner 3b on the exhaust side is passed through the communication path 14 to the space 1
0b, the space 10b
Alternatively, complete combustion occurs in the space 10b and the heat storage unit 2b. The exhaust gas from which the unburned components are completely burned is stored in the heat storage section 2b.
Then, the air is exhausted by the exhaust blower 7 through the exhaust passages 9 b and 9.

On the other hand, contrary to the above, the switching valve 5 in black
b, 8a, and 12b are open and the switching valve 5 is not blackened
In the state where a, 8b, and 12a are closed, the combustion air passes from the air supply blower 4 through the air supply paths 6, 6b, passes through the heat storage unit 2b, reaches the space 10b, and is supplied from the fuel supply path 13b. The fuel gas is mixed with the fuel gas to be burned in the furnace 11, and a part of the combustion air reaching the space 10 b passes through the communication path 14 as complete combustion air, and then the exhaust-side burner 3 a Is supplied to the space 10a. Therefore, similarly to the above, while reducing combustion is performed in the furnace 11, complete combustion of unburned components is performed in the burner 3a on the exhaust side.

As can be seen from the above description, in the present invention, the exhaust-side burner 3b (or 3a) is used for complete combustion of the unburned portion by performing reduction combustion in the furnace 11.
Is supplied through the air supply passage 6a (or 6b) of the burner 3a (or 3b) on the combustion side. The opening operation of the switching valve 5a (or 5b), that is, the burner 3
a (or 3b), so that each of the switching valves 5a, 5b at the time of combustion switching of the burners 3a, 3b.
b, and when the temperature control by the time proportional control is performed, when the burners 3a and 3b
1 is not supplied with the air for complete combustion.

The complete combustion air supplied to the space 10b (or 10a) of the exhaust side burner 3b (or 3a) is supplied to the heat storage section 2a of the combustion side burner 3a (or 3b).
(Or 2b), the oxidation reaction of the unburned portion proceeds quickly, and this reaction region, that is, the space 10a,
10b can be reduced in size.

The flow rate of the combustion air supplied from the combustion side burner 3a (or 3b) into the furnace 11 and the communication path 1
4, the space 1 of the burner 3b (or 3a) on the exhaust side
The ratio of the flow rate of the complete combustion air supplied to 0b (or 10a) is maintained substantially constant even when the total flow rate of the combustion air supplied through the air supply path 6 changes, so that the position proportional control is performed. Thus, even when temperature control is performed, reduction combustion can be performed stably. When performing the position proportional control, a flow control mechanism is provided in the air supply path 6, the exhaust path 9, and the fuel supply paths 13a and 13b.

As described above, the fuel supply path 13a (1
3b) and the communication path 14 are connected to the fuel supply path 13a (13
The fuel gas supplied from b) is appropriately arranged so as not to flow into the communication path 14.
When a and 13b are provided in the spaces 10a and 10b,
For example, the arrangement can be as shown in the figure, and in addition, the fuel supply paths 13a, 13b
Instead of 10b, it can be arranged to be connected to the furnace body 1.

FIG. 2 is a systematic explanatory diagram showing a second embodiment of the regenerative burner system to which the present invention is applied. In this embodiment, components corresponding to the components in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted. In the second embodiment, a flow control mechanism 15 is provided in the communication path 14 in the first embodiment. By providing such a flow control mechanism, the burner 3a (or 3b) on the combustion side is provided. ) From furnace 1
1 to appropriately adjust the flow rate of the combustion air supplied to 1 and the flow rate of the complete combustion air supplied to the space 10b (or 10a) of the burner 3b (or 3a) on the exhaust side through the communication path 14. Can be.

In this embodiment, in order to perform temperature control by position proportional control, the flow control mechanism 1 is provided in each of the air supply path 6, the exhaust path 9, and the fuel supply paths 13a and 13b.
6, 17, 18a, and 18b, and the flow control mechanisms 16, 17, 18a, and 18b are connected to the communication path 1 described above.
In combination with the flow control mechanism 15 of 4, the control of the reduction combustion can be performed with higher accuracy. Note that these flow control mechanisms can be constituted by a combination of an orifice 19 and a flow control valve 20, as exemplified in the flow control mechanism 16.

The flow control mechanism 15 of the communication path 14
The present invention is also effective in a configuration in which temperature control is performed by time proportional control instead of position proportional control.

Next, FIG. 4 is a systematic explanatory diagram showing a third embodiment of the regenerative burner system to which the present invention is applied. In this embodiment, the components corresponding to those in FIG. The same reference numerals are given to the same elements, and duplicate description will be omitted. In the third embodiment, the burners 3a and 3b forming a pair are burners connected to the end of the radiant tube 21. In such a configuration, since the burners 3a and 3b forming a pair are generally arranged at a short distance, the communication path 14 may be short and NOx can be easily reduced.

[0032]

As described above, the present invention is as described above, so that the reduction combustion in the furnace in the regenerative burner system can be performed inexpensively and reliably, and the non-oxidizing heating of the object to be heated by the reduction combustion can be performed. Low NOx can be achieved. Even when the burner is for a radiant tube, it is possible to reduce NOx.

[Brief description of the drawings]

FIG. 1 is a systematic explanatory diagram showing a first embodiment of a regenerative burner system to which the present invention has been applied.

FIG. 2 is a systematic explanatory diagram showing a second embodiment of a regenerative burner system to which the present invention has been applied.

FIG. 3 is a systematic explanatory diagram showing a third embodiment of a regenerative burner system to which the present invention has been applied.

FIG. 4 is a systematic explanatory diagram showing a conventional reduction combustion method in a regenerative burner system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace main body 2a, 2b Heat storage body 3a, 3b Burner 4 Air supply blower 5a, 5b Switching valve 6, 6a, 6b Air supply path (oxidant supply path) 7 Exhaust blower 8a, 8b Switching valve 9, 9a, 9b Exhaust path DESCRIPTION OF SYMBOLS 10a, 10b Space part 11 Inside furnace 12a, 12b Gas switching valve 13a, 13b Fuel supply path 14 Communication path 15 Flow control mechanism 16, 17, 18a, 18b Flow control mechanism 19 Orifice 20 Flow control valve 21 Radiant tube

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F23L 9/00 F23L 9/00 15/02 15/02 F term (reference) 3K017 AA01 AA06 AB05 AB07 AD05 BA01 BA06 BB07 3K023 KA07 KB01 KB13 KC01 QA16 QB13 QC07 3K065 TA01 TA14 TD02 TD05 TF03 TH02 TP03 3K091 AA01 BB05 BB26 CC06 CC22 DD08 EA04 EA14 EA24 EA28

Claims (4)

[Claims] A burner forming a pair having a heat storage section is provided in a furnace main body, and each burner is connected to an oxidant supply path and a discharge path each having a switching valve, and is connected to the furnace main body with respect to the heat storage section. In the regenerative burner system configured to communicate with the inside of the furnace via the space configured as described above, the reduction section in the regenerative burner system characterized in that the space of each burner is communicated with a communication path. mechanism 2. The reduction combustion mechanism in the regenerative burner system according to claim 1, wherein a flow control mechanism is provided in the communication path. 3. The reduction combustion mechanism in the regenerative burner system according to claim 1, wherein the pair of burners is a burner for a radiant tube connected to an end of the radiant tube. 4. The reduction combustion mechanism according to claim 1, wherein the oxidant is supplied from the oxidant supply path to the burner on the combustion side at a flow rate for completely burning the fuel, and is supplied to the combustion side. In the furnace, the stoichiometry supplied from the burner on the combustion side in the furnace by supplying a part of the oxidant reaching the space through the heat storage section of the burner to the space of the burner on the exhaust side via the communication path A regenerative burner system characterized by performing reduction combustion with an oxidant having a ratio of 1 or less and completely combusting unburned components reaching an exhaust-side burner with an oxidant supplied through the communication path. Reduction combustion method