WO2017159080A1

WO2017159080A1 - Industrial furnace

Info

Publication number: WO2017159080A1
Application number: PCT/JP2017/003322
Authority: WO
Inventors: 健介川端; 毅有松; 寿雄惠上
Original assignee: 中外炉工業株式会社
Priority date: 2016-03-15
Filing date: 2017-01-31
Publication date: 2017-09-21
Also published as: TWI686570B; TW201734365A; JP6525909B2; JP2017166732A

Abstract

An industrial furnace that supplies a fuel gas and combustion air to a combustion burner, uses the combustion burner to combust the fuel gas inside a furnace, and discharges combusted combustion exhaust gas from inside the furnace through an exhaust pipe. An exhaust gas processing part that houses a three-way catalyst is provided to the exhaust pipe.

Description

Industrial furnace

The present invention relates to an industrial furnace which supplies a fuel gas and combustion air to a combustion burner, burns the fuel gas in the furnace by the combustion burner, and discharges the combustion exhaust gas from the furnace through the exhaust pipe. It is a thing. In particular, as described above, when the fuel gas and the combustion air are supplied to the combustion burner and the fuel gas is burned in the furnace by the combustion burner, nitrogen oxides harmful to the combustion exhaust gas (hereinafter referred to as NOx). In addition, it is characterized in that combustion exhaust gas is prevented from being discharged to the outside through the exhaust pipe in the state where unburned component gas such as CO gas or hydrocarbon gas (HC) is contained. is there.

Conventionally, in industrial furnaces such as heating furnaces and heat treatment furnaces, in general, a fuel gas and air for combustion are supplied to a combustion burner to heat the object to be heated, and the fuel gas is contained in the furnace by the combustion burner. The combustion exhaust gas from the inside of the furnace is discharged through the exhaust pipe.

Here, in such an industrial furnace, in order to supply the fuel gas and the combustion air to the combustion burner as described above and burn the fuel gas in the furnace, the combustion with respect to the fuel gas is performed to enhance the combustion efficiency. If the amount of air is increased to perform combustion, a large amount of NOx is generated at the time of combustion, and the combustion exhaust gas containing a large amount of NOx is discharged from the inside of the furnace to the outside through the exhaust pipe, resulting in a serious environmental damage. In particular, in recent years, there has been a demand to significantly reduce NOx in combustion exhaust gas.

On the other hand, if combustion is performed while reducing the amount of combustion air to fuel gas in order to suppress NOx from being contained in the combustion exhaust gas, the combustion efficiency decreases, and CO gas or hydrocarbons in the combustion exhaust gas ( HC) A large amount of unburned component gas such as gas remains, and the unburned component gas is discharged from the inside of the furnace through the exhaust pipe to the outside, which causes problems in terms of safety and environment.

And, in recent years, as shown in Patent Document 1, the combustion exhaust gas from a radiant tube burner is purified using a nitrogen oxide reduction catalyst, and the air ratio μ (the actual amount of air) to the obtained NOx purification gas It has been proposed that after combustion air is added so that (theoretical air amount) becomes 1.0 or more, an oxidation catalyst is further used to oxidize and remove unburned components.

Here, in the case shown in Patent Document 1, a first exhaust gas processing unit containing a nitrogen oxide reduction catalyst and a second exhaust gas processing unit containing an oxidation catalyst are provided. It is necessary to supply air between the exhaust gas processing unit and the second exhaust gas processing unit, and there is a problem that the apparatus becomes complicated and becomes large.

In addition, as one of the exhaust gas treatment, CO, HC, and NOx which are harmful to safety, environment, human body, etc. are oxidized / reduced by three-way catalyst, converted to H ₂ O, CO ₂ , N ₂ and purified For example, as shown in Patent Document 2, in an alternating combustion burner having a heat storage layer, a three-way catalyst layer is provided in the heat storage layer of each burner section to match the activation conditions of the three-way catalyst layer. Thus, there has also been proposed one in which the air ratio in the furnace is adjusted to 0.98 to 1.02 for combustion.

However, what was shown by patent document 2 was limited in the kind and operating condition of a furnace to be used, and it was difficult to use it under various conditions in various furnaces.

JP 2001-241619 A JP-A-7-133905

According to the present invention, the fuel gas and the combustion air are supplied to the combustion burner, the fuel gas is burned in the furnace by the combustion burner, and the combustion exhaust gas is discharged from the furnace through the exhaust pipe. It is an object of the present invention to solve the above-mentioned problems in an industrial furnace.

That is, in the industrial furnace according to the present invention, the fuel gas is supplied to the combustion burner with the fuel gas and the combustion air, and after the fuel gas is burned in the furnace by the combustion burner, the combustion exhaust gas is discharged from the furnace into the exhaust pipe. Prevents exhaust gases from being emitted outside when the exhaust gases contain harmful NOx and unburned gases such as CO gas and hydrocarbon (HC) gas. To be a subject.

In the industrial furnace according to the present invention, in order to solve the problems as described above, the fuel gas and the combustion air are supplied to the combustion burner, and the fuel gas is burned in the furnace by the combustion burner, In an industrial furnace in which combustion exhaust gas is discharged from the inside of the furnace through an exhaust pipe, the exhaust pipe is provided with an exhaust gas processing unit in which a three-way catalyst is accommodated.

In the industrial furnace, NOx contained in the combustion exhaust gas is reduced by the unburned component gas contained in the combustion exhaust gas by the three-way catalyst contained in the exhaust gas processing unit. In this case, when supplying the fuel gas and the combustion air to the combustion burner, if the air ratio μ of the combustion air is made 1.0 or less by reducing the amount of the combustion air to the fuel gas, NOx generated at the time of combustion Thus, the amount of NOx decreases and the NOx contained in the combustion exhaust gas decreases, and the NOx contained in the combustion exhaust gas is sufficiently reduced by the three-way catalyst by the unburned component gas contained in the combustion exhaust gas.

Further, in the industrial furnace according to the present invention, the fuel gas for guiding a part of the fuel gas supplied to the combustion burner to a position upstream of the exhaust gas processing unit provided in the exhaust pipe in the exhaust gas discharge direction. Preferably, a guideway and control means for controlling the amount of fuel gas guided through the fuel gas guideway are provided.

Here, in the control means, the amount of fuel gas guided through the fuel gas guide path is controlled in accordance with the amount of nitrogen oxide contained in the combustion exhaust gas.

Then, when supplying the fuel gas and the combustion air to the combustion burner as described above, in order to increase the combustion efficiency, the fuel gas is supplied to the combustion burner with the amount of the combustion air relative to the fuel gas increased. As a result of the combustion, when the exhaust gas contains a large amount of NOx, the above-mentioned control is carried out before the above-mentioned exhaust gas is led to the exhaust gas processing unit containing the three-way catalyst through the exhaust pipe. A proper amount of fuel gas is supplied through the fuel gas guiding path by means. In this way, the combustion exhaust gas containing a large amount of NOx and the appropriate amount of fuel gas are brought together to the exhaust gas treatment unit, and the NOx in the combustion exhaust gas is sufficiently reduced by the action of the three-way catalyst. Will be discharged.

In the industrial furnace according to the present invention, the unburned component gas contained in the combustion exhaust gas discharged from the exhaust gas processing unit at a position downstream of the exhaust gas processing unit provided in the exhaust pipe in the discharge direction of the combustion exhaust gas. Preferably, a post-combustion device is provided to burn the In this way, even if unburned component gas remains in the combustion exhaust gas processed in the exhaust gas processing unit, the unburned component gas is burned by the post-combustion device and oxidized to CO ₂ or H ₂ O. As a result, the unburned component gas is prevented from being discharged.

In the industrial furnace according to the present invention, heat exchange means for heating the combustion air by the heat of the combustion exhaust gas is provided, and the combustion air heated by the heat exchange means is supplied to the combustion burner. It is preferable to In this way, the heat of the combustion exhaust gas can be effectively used to perform efficient combustion.

In the industrial furnace according to the present invention, the fuel gas and the combustion air are supplied to the combustion burner, the fuel gas is burned in the furnace, and the combustion exhaust gas is discharged from the furnace through the exhaust pipe. Thus, an exhaust gas processing unit containing a three-way catalyst is provided in the exhaust pipe, and the above-mentioned combustion exhaust gas is led to the above-mentioned exhaust gas processing unit, and harmful NOx in the combustion exhaust gas, or CO gas or hydrocarbon (HC) The unburned component gas consisting of gas was properly treated.

As a result, in the industrial furnace according to the present invention, when the fuel gas is mixed with the combustion air and burned in the furnace, NOx and unburned component gas in the combustion exhaust gas are provided in the exhaust pipe, the exhaust gas processing unit The exhaust gas can be properly discharged to the outside through the exhaust pipe in a safe state where the combustion exhaust gas is properly treated and NOx and unburned component gas are not contained in the combustion exhaust gas.

It is the schematic explanatory drawing which showed the state which uses the industrial furnace which concerns on the 1st Embodiment of this invention. It is the schematic explanatory drawing which showed the state which uses the industrial furnace which concerns on the 2nd Embodiment of this invention. It is the schematic explanatory drawing which showed the state which uses the industrial furnace which concerns on the 3rd Embodiment of this invention. It is the schematic explanatory drawing which showed the state which uses the industrial furnace which concerns on the 4th Embodiment of this invention. It is the schematic explanatory drawing which showed the state which uses the industrial furnace which concerns on the 5th Embodiment of this invention.

Hereinafter, an industrial furnace concerning an embodiment of the present invention is concretely explained based on an accompanying drawing. In addition, the industrial furnace which concerns on this invention is not limited to what was shown to the following embodiment, In the range which does not change the summary of invention, it can change suitably and can implement.

Here, in the industrial furnace according to the first embodiment, as shown in FIG. 1, a combustion burner 12 is provided on the furnace wall 11 of the furnace 10, and the combustion burner 12 is provided with hydrocarbons (through fuel gas supply pipe 21) HC) A fuel gas such as a gas is supplied and at the same time a combustion air is supplied through a combustion air supply pipe 22, and the fuel gas and the combustion air are mixed in the combustion burner 12 to make the fuel gas in the furnace 10. I am trying to burn it.

Further, an exhaust pipe 13 for discharging the combustion exhaust gas after burning the fuel gas in the furnace 10 in this manner from the inside of the furnace 10 is provided, and the exhaust gas processing unit 23 in which the three-way catalyst is accommodated in the exhaust pipe 13 is provided. The combustion exhaust gas after combustion in the furnace 10 is introduced to the exhaust gas processing unit 23 through the exhaust pipe 13 so that the three-way catalyst accommodated in the exhaust gas processing unit 23 processes the combustion exhaust gas. .

Here, in the industrial furnace according to this embodiment, when the fuel gas and the combustion air are supplied to the combustion burner 12 through the fuel gas supply pipe 21 and the combustion air supply pipe 22, NOx generated during the combustion can be obtained. In order to reduce the amount, the amount of combustion air to the fuel gas is reduced, for example, the air ratio μ of the combustion air is set to 1.0 or less so that the fuel gas is burned in the combustion burner 12. Do.

When the amount of combustion air relative to the fuel gas is reduced as described above, NOx contained in the combustion exhaust gas is reduced, and unburned component gas such as CO gas or hydrocarbon (HC) gas is contained in the combustion exhaust gas. Will remain.

Then, when the combustion exhaust gas in which the NOx and the unburned component gas remain in this way is led from the inside of the furnace 10 to the exhaust gas processing unit 23 through the exhaust pipe 13, the three-way catalyst accommodated in the exhaust gas processing unit 23 As the NOx remaining in the combustion exhaust gas reacts with the unburned component gas, NOx is reduced to N ₂ , and the unburned component gas is discharged in the state oxidized to CO ₂ or H ₂ O Become.

Here, when treating the combustion exhaust gas in which the NOx and the unburned component gas remain in this way with the three-way catalyst contained in the exhaust gas processing unit 23, the amount of combustion air for the fuel gas is further reduced The amount of unburned component gas in the exhaust gas increases, and there is a risk that exhaust gas from which the unburned component gas remains may be discharged from the exhaust gas processing unit 23 without being sufficiently treated by the three-way catalyst contained in the exhaust gas processing unit 23 .

Therefore, in the industrial furnace according to the second embodiment, as shown in FIG. 2, in the industrial furnace according to the first embodiment, combustion is performed more than the exhaust gas processing unit 23 provided in the exhaust pipe 13 A post-combustion device 24 is provided at a position downstream of the exhaust gas discharge direction, and a post-combustion fuel gas from the post-combustion fuel gas supply pipe 24a and a post-combustion air are provided to the post-combustion device 24 if necessary. The post combustion air is supplied from the supply pipe 24b.

Then, in the industrial furnace according to the second embodiment, the unburned component gas remaining in the combustion exhaust gas discharged from the exhaust gas processing unit 23 is burned in the post-combustion device 24 and the unburned component gas is CO ₂ gas And H ₂ O are oxidized and discharged.

Therefore, even if the combustion exhaust gas containing the unburned component gas is discharged from the exhaust gas processing unit 23 without sufficiently processing the unburned component gas in the exhaust gas processing unit 23, the unburned component gas is The combustion device 24 burns and is processed, and the unburned component gas can be reliably prevented from being discharged. In this embodiment, the post-combustion device 24 is used to burn the unburned component gas remaining in the combustion exhaust gas with a flame, but the post-combustion device 24 is not limited to such a device, such as electric heating The unburned component gas remaining in the combustion exhaust gas can also be burned by

Next, in the industrial furnace according to the third embodiment, as shown in FIG. 3, in the industrial furnace according to the first embodiment, a combustion air supply pipe for supplying combustion air to the combustion burner 12 In place of 22, the heat exchange unit (heat exchange means) 25a for heating the combustion air by the heat of the combustion exhaust gas is provided in the exhaust pipe 13 for guiding the combustion exhaust gas from the inside of the furnace 10 to the exhaust gas processing unit 23. The heat exchange section 25a is provided with a combustion air guide pipe 25b for guiding the combustion air, and the heating air supply pipe 25c for supplying the combustion air heated in the heat exchange section 25a to the combustion burner 12 Is provided.

Then, in the industrial furnace according to the third embodiment, as described above, the combustion air is guided to the heat exchange unit 25a through the combustion air guide pipe 25b, and the heat exchange unit 25a burns the heat by the heat of the combustion exhaust gas. The heating air is heated, and thus heated combustion air is supplied to the combustion burner 12 through the heating / combustion air supply pipe 25c, and the combustion air and fuel gas thus heated are burned. The fuel gas is burned in the furnace 10 by mixing at 12.

In this way, when the fuel gas is mixed with the combustion air and burned, the heat of the combustion exhaust gas can be effectively used. Further, by performing heat exchange between the combustion exhaust gas and the combustion air in the heat exchange unit 25a in this manner, the temperature of the combustion exhaust gas led to the exhaust gas processing unit 23 from inside the furnace 10 through the exhaust pipe 13 Is reduced, and the temperature of the combustion exhaust gas is prevented from reaching a temperature exceeding the temperature range in which the three-way catalyst contained in the exhaust gas processing unit 23 is used, and the three-way catalyst can properly treat the combustion exhaust gas. It will be. In the present embodiment, the heat exchange unit 25a is provided in the exhaust pipe 13. However, the heat exchange unit 25a may be provided outside the exhaust pipe 13.

Next, in the industrial furnace according to the fourth embodiment, as shown in FIG. 4, in the industrial furnace according to the first embodiment, the fuel gas supplied to the combustion burner 12 through the fuel gas supply pipe 21 is A fuel gas guiding passage 26 for guiding a part of the exhaust gas processing unit 23 provided in the exhaust pipe 13 to a position upstream of the exhaust gas in the discharge direction, and the fuel gas guiding passage 26 burns in the exhaust gas processing unit 23 A control valve (control means) 26a is provided to control the amount of fuel gas supplied to the exhaust pipe 13 at a position upstream of the exhaust gas discharge direction.

In the industrial furnace according to the fourth embodiment, the fuel gas guide passage is controlled by the control valve 26 a in correspondence to the amount of NOx contained in the combustion exhaust gas after being burned in the combustion burner 12. The amount of fuel gas supplied to the exhaust pipe 13 at a position upstream of the exhaust gas processing unit 23 in the discharge direction of exhaust gas from the exhaust gas processing unit 23 is controlled.

Here, in order to increase the combustion efficiency in supplying the fuel gas and the combustion air supplied to the combustion burner 12 through the fuel gas supply pipe 21 and the combustion air supply pipe 22, the air ratio of the combustion air is increased. When the amount of combustion air to fuel gas is increased such that μ exceeds 1.0 and the fuel gas is burned in the above-described combustion burner 12, the fuel gas is burned by a sufficient amount of combustion air. While unburned component gas such as CO gas and hydrocarbon (HC) gas in the combustion exhaust gas decreases, a large amount of NOx is generated at the time of combustion, and a large amount of the NOx is contained in the combustion exhaust gas.

When the combustion exhaust gas contains a large amount of NOx, the control valve 26a causes the fuel gas guide passage 26 to flow upstream of the exhaust gas processing portion 23 in the exhaust gas discharge direction. The amount of fuel gas guided to the exhaust pipe 13 at the position is controlled to supply an appropriate amount of fuel gas to a position upstream of the exhaust gas processing unit 23 in the exhaust gas discharge direction, and a large amount of NOx is contained. It is made to guide to the exhaust gas processing part 23 which accommodated the three-way catalyst together with the combustion exhaust gas. In this way, by the action of the three-way catalyst housed in the exhaust gas treatment unit 23, and NOx in the combustion exhaust gas reacts with the fuel gas, the NOx is reduced to N _2, the fuel gas is CO ₂ Ya It will be discharged in the state oxidized to H ₂ O.

Next, in the industrial furnace according to the fifth embodiment, as shown in FIG. 5, in the industrial furnace according to the fourth embodiment, as shown in the industrial furnace according to the second embodiment In the furnace 10, as shown in the industrial furnace according to the third embodiment, a post-combustion device 24 is provided in the exhaust pipe 13 at a position downstream of the exhaust gas processing unit 23 in the exhaust gas discharge direction. In the exhaust pipe 13 for introducing the combustion exhaust gas from the exhaust gas into the exhaust gas processing unit 23, the heat exchange unit 25a for heating the combustion air by the heat of the combustion exhaust gas is provided, and the combustion air to be heated is guided to the heat exchange unit 25a. A combustion air guide pipe 25b is provided, and a heating combustion air supply pipe 25c for supplying the combustion air heated in the heat exchange section 25a to the combustion burner 12 is provided.

Then, in the industrial furnace according to the fifth embodiment, as in the industrial furnace according to the third embodiment, the combustion air is guided to the heat exchange unit 25a through the combustion air guide pipe 25b, and this thermal In the exchange section 25a, the combustion air is heated by the heat of the combustion exhaust gas, and the heated combustion air is supplied to the combustion burner 12 through the heating / combustion air supply pipe 25c to heat the combustion burner 12 Air and fuel gas are mixed in the combustion burner 12 so that the fuel gas is burned in the furnace 10.

In this way, when the fuel gas is mixed with combustion air and fuel gas and burned as described above, the heat of the combustion exhaust gas can be effectively used, and the exhaust gas from the furnace 10 can be used. The temperature of the combustion exhaust gas led to the processing unit 23 decreases, and the temperature of the combustion exhaust gas is prevented from exceeding the temperature range where the three-way catalyst contained in the exhaust gas processing unit 23 is used. The catalyst can properly treat the exhaust gas for combustion.

Further, in the industrial furnace according to the fifth embodiment, the amount of fuel gas guided through the fuel gas guide path 26 is increased, which is required to reduce NOx in the combustion exhaust gas to N _2. When a larger amount of fuel gas is introduced to the exhaust gas processing unit 23, the exhaust gas processing unit 23 discharges the combustion exhaust gas in which the unburned component gas remains. In such a case, as in the industrial furnace according to the second embodiment, the unburned component gas remaining in the combustion exhaust gas discharged from the exhaust gas processing unit 23 is burned in the post-combustion device 24, The gas can be oxidized to CO ₂ gas or H ₂ O and discharged.

10: furnace 11: furnace wall 12: combustion burner 13: exhaust pipe 21: fuel gas supply pipe 22: combustion air supply pipe 23: exhaust gas processing unit 24: post combustion device 24a: fuel gas supply pipe 24b for post combustion: rear Combustion air supply pipe 25a: Heat exchange unit (heat exchange means)
25b: combustion air guide pipe 25c: heating combustion air supply pipe 26: fuel gas guide path 26a: control valve (control means)
μ: Air ratio

Claims

In the industrial furnace, the fuel gas and the combustion air are supplied to the combustion burner, the fuel gas is burned in the furnace by the combustion burner, and the combustion exhaust gas is discharged from the furnace through the exhaust pipe. An industrial furnace characterized in that an exhaust gas processing unit containing a three-way catalyst is provided in a pipe.
The industrial furnace according to claim 1, wherein the three-way catalyst contained in the exhaust gas processing unit reduces nitrogen oxides contained in the combustion exhaust gas with unburned component gas contained in the combustion exhaust gas. Industrial furnace.
The industrial furnace according to claim 1, wherein the fuel gas guide for guiding a part of the fuel gas supplied to the combustion burner to a position upstream of the exhaust gas processing unit provided in the exhaust pipe in the exhaust gas discharge direction. An industrial furnace provided with a passage and control means for controlling the amount of fuel gas guided through the fuel gas guide passage.
The industrial furnace according to claim 3, wherein the control means controls the amount of fuel gas guided to the exhaust pipe through the fuel gas guide path in accordance with the amount of nitrogen oxides contained in the combustion exhaust gas. An industrial furnace characterized by
The industrial furnace according to any one of claims 1 to 4, wherein the combustion exhausted from the exhaust gas processing unit at a position downstream of the exhaust gas processing unit provided in the exhaust pipe in the exhaust gas discharge direction. An industrial furnace provided with a post-combustion device for burning unburned component gas contained in exhaust gas.
The industrial furnace according to any one of claims 1 to 5, further comprising: heat exchange means for heating the combustion air by the heat of the combustion exhaust gas, and the combustion air heated by the heat exchange means is An industrial furnace characterized by being fed to the above-mentioned combustion burner.