JPH07229615A - Method and device for treating waste gas - Google Patents

Abstract

PURPOSE:To reduce the using amount of auxiliary fuel, prevent the poisoning of catalyst and permit waste gas treatment stabilized for a long period of time. CONSTITUTION:The present invention is referred to a treating method of waste gas containing the poisonous constituents of catalyst employing a waste gas disposal device having a combustion furnace 1 equipped with a catalyst combustion type auxiliary combustion burner 4 and a part of treated gas (c) is introduced into the outlet port of a combustion catalyst layer 8 for the catalyst combustion type auxiliary combustion burner 4 to burn it in combustion gas upon effecting catalyst combustion of auxiliary fuel (a) while remaining gas to be treated is introduced into combustion gas having a temperature higher than that of combustion gas upon catalyst combustion to burn it. According to this method, the using amount of the auxiliary fuel is reduced, the life of the catalyst is elongated and waste gas disposal, stabilized for a long period of time, can be effected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treating apparatus and a treating method, and more particularly to an exhaust gas treating apparatus and a treating method for burning and detoxifying combustible low-calorie exhaust gas containing a catalyst poisoning component.

[0002]

2. Description of the Related Art In various industrial devices, so-called exhaust gas, which becomes unnecessary in various manufacturing processes, is discharged. Such exhaust gas often contains low-concentration components, harmful substances as trace components, and malodorous substances,
An exhaust gas treatment device for detoxifying and deodorizing these harmful substances and malodorous substances is provided.

As an exhaust gas treating apparatus for combusting an exhaust gas containing a low concentration of combustible gas such as hydrocarbon, for example, a combustion type exhaust gas treating apparatus is generally used. Such a combustion type exhaust gas treatment device is roughly classified into a direct combustion type and a catalytic combustion type. The direct combustion method can treat even if the gas to be treated contains dust, sulfur oxides, halogen compounds, etc., and can be applied to a relatively wide range. For example, about 700
It is a method of heating above ℃ and burning and decomposing odorous and harmful components such as hydrocarbons to render them harmless.

FIG. 3 is a schematic system diagram of such a conventional direct combustion type exhaust gas treating apparatus. This apparatus comprises a combustion furnace 1 having an auxiliary combustion burner 4, a waste heat recovery boiler 2 and a chimney 3 provided in a flue of a downstream thereof, an exhaust gas pipe 11 for introducing a low-calorie exhaust gas c into the combustion furnace 1, It comprises an auxiliary fuel pipe 5 and an air pipe 6 for supplying the auxiliary fuel a and the air b to the auxiliary burner 4, respectively.
The auxiliary fuel a introduced into the auxiliary combustion burner 4 from is mixed with the air b introduced from the pipe 6 and burned, and the combustion heat of the combustion furnace 1 heats the combustion furnace 1 to, for example, 700 ° C. or higher. An exhaust gas introducing pipe 11 is provided in the combustion furnace 1 heated to 700 ° C. or higher.
The low-calorie exhaust gas c, which is the gas to be treated, is introduced via the and burned. The generated combustion exhaust gas is subjected to heat recovery by the waste heat recovery boiler 2 in the downstream, and then is released to the atmosphere through the chimney 3.

On the other hand, the catalytic combustion system is a system in which the harmful and malodorous components in the exhaust gas are oxidized and burned at a temperature of around 300 ° C. by the oxidation action of the catalyst components such as platinum to decompose and render them harmless. FIG. 4 is a schematic system diagram of such a conventional catalytic combustion type exhaust gas treatment apparatus. This apparatus includes a combustion furnace 1 having an auxiliary combustion burner 4, a combustion catalyst layer 8 provided in the combustion furnace 1, an air preheater 7 provided in a flue of a wake of the combustion furnace 1, a waste heat recovery boiler. 2 and a chimney 3, an exhaust gas introducing pipe 11 for introducing a low-calorie exhaust gas c into the combustion furnace 1, an auxiliary fuel pipe 5 for supplying an auxiliary fuel a to the auxiliary combustion burner 4,
The auxiliary combustion burner 4 and the air pipe 6 for supplying the air b to the air preheating pipe 7, and the combustion furnace 1 and the combustion catalyst layer 8
Is heated to a predetermined temperature by the auxiliary fuel a that burns in the auxiliary combustion burner 4 and the preheated air b that flows in through the air preheating pipe 7. The low-calorie exhaust gas c is introduced into the heated combustion furnace 1 through the exhaust gas introducing pipe 11, and the mixing portion 9 of the combustion furnace 1 is introduced.
After being mixed with the preheated air b at 1, the gas flows into the combustion catalyst layer 8 and burns.

Since such a catalytic combustion system can lower the treatment temperature as compared with the direct combustion system, the amount of the auxiliary fuel a used can be greatly reduced.

[0007]

However, the above-mentioned conventional direct combustion system requires a large amount of auxiliary fuel for maintaining the gas to be treated at a high temperature, and the amount of NOx generated by the high temperature combustion of the auxiliary fuel in the auxiliary combustion burner is large. There is a problem that On the other hand, in the catalytic combustion system, phosphorus (P), silicon (Si), tin (S), which are poisoning components of the combustion catalyst, are used.
When treating an exhaust gas containing n), zinc (Zn), halogen, sulfur, etc., there is a drawback that the catalyst deteriorates and the life becomes extremely short. Furthermore, the heat resistance of the combustion catalyst has a limit, and when the heat value of the exhaust gas to be treated is relatively high, a large amount of dilution air is required, and the required catalyst amount also increases.

An object of the present invention is to solve the above-mentioned problems of the prior art, to reduce the amount of auxiliary fuel used, to prevent poisoning of the combustion catalyst, and to perform stable exhaust gas treatment, and It is to provide a processing method.

[0009]

In order to achieve the above object, the invention claimed in the present application is as follows. (1) A method of treating an exhaust gas containing a catalyst poisoning component using an exhaust gas treating apparatus having a combustion furnace provided with a catalytic combustion type auxiliary combustion burner, wherein the catalyst layer outlet of the catalytic combustion type auxiliary combustion burner is treated. In a combustion gas having a temperature higher than that of the combustion gas at the time of catalytic combustion, which is generated by introducing a part of the gas and combusting a part of the gas to be treated in the combustion gas at the time of catalytic combustion of the auxiliary fuel An exhaust gas treatment method, characterized in that the remaining gas to be treated is introduced and burned. (2) In a device for treating exhaust gas containing a catalyst poisoning component, which comprises a combustion furnace provided with an auxiliary combustion burner and an exhaust gas introduction pipe for introducing exhaust gas into the combustion furnace, the auxiliary combustion burner is a catalytic combustion type auxiliary combustion burner. An exhaust gas treatment apparatus, characterized in that a branch pipe is provided in the exhaust gas introduction pipe, and an outlet of the branch pipe is opened to a catalyst layer outlet of the catalytic combustion type auxiliary combustion burner.

[0010]

[Function] The auxiliary combustion burner provided in the combustion furnace is a catalytic combustion auxiliary combustion burner, and a branch pipe of the exhaust gas introduction pipe opening to the outlet of the combustion catalyst layer of the catalytic combustion auxiliary combustion burner is provided, whereby the catalyst poisoning component is removed. Low-calorie exhaust gas that contains and is difficult to burn alone (for example, calorific value of 200 to 400 Kcal /
m ³ · N), by injecting a part of it into the combustion catalyst layer outlet of the auxiliary combustion burner through the branch pipe, the auxiliary fuel self-combusts due to the effect of the high-temperature exhaust gas when catalytically burned. Will be able to. Further, the amount of heat generated by the catalytic combustion of the auxiliary fuel and the amount of heat generated by the combustion of a part of the treated exhaust gas, after that, the heat amount necessary for the remaining treated gas introduced into the combustion furnace to self-combust Secure. That is, catalytic combustion of auxiliary fuel,
Combustion of a part of the gas to be treated injected to the outlet of the catalyst layer acts as a conventional auxiliary combustion burner and promotes combustion of the remaining gas to be treated.

In the present invention, the exhaust gas to be treated is a low calorie exhaust gas, but its calorific value is 100 Kc.
It is preferably at least al / m ³ · N, more preferably at least 200 Kcal / m ³ · N. If the calorific value is smaller than this, the flame holding property is not sufficient, and accurate control of the atmospheric temperature and the residence time (for example, 0.5 to 1 second) is required.

[0012]

EXAMPLES Next, the present invention will be described in more detail by way of examples. FIG. 1 is a system diagram of an exhaust gas treating apparatus showing an embodiment of the present invention. This apparatus comprises a combustion furnace 1 equipped with a catalytic combustion type auxiliary burner 4, an air preheater 7, a waste heat recovery boiler 2 and a chimney 3 which are sequentially provided in an exhaust gas flue of the combustion furnace 1, and a gas to be treated. An exhaust gas pipe 11 for introducing a certain low-calorie exhaust gas c into the combustion furnace 1, and an exhaust gas branch pipe 10 which is branched from the exhaust gas pipe 11 and penetrates the combustion catalyst layer 8 of the auxiliary combustion burner 4 to open at its outlet, It is mainly composed of an auxiliary fuel pipe 5 for introducing the auxiliary fuel a into the auxiliary burner 4 and an air pipe 6 for introducing air b into the auxiliary burner 4 via the air preheater 7. 9
Is a mixing portion of the catalytic combustion type auxiliary burner 4.

In such a structure, the auxiliary fuel a is
It is introduced into the mixing section 9 of the auxiliary combustion burner 4 through the pipe 5, passes through the air pipe 6, and the temperature required for catalytic combustion in the air preheater 7,
For example, it is heated to 200 to 450 ° C. and uniformly mixed with the inflowing air b, then flows into the combustion catalyst layer 8 and burns, and becomes high temperature combustion gas. The high temperature combustion gas in this catalytic combustion may have a temperature sufficient to cause a part of the exhaust gas to be treated injected at the outlet of the combustion catalyst layer 8 to undergo gas phase combustion, which will be described later, and considering flame holding stability. For example, the temperature is 600 ° C. or higher, preferably 650 to 750 ° C. A part of the low-calorie exhaust gas c, which is the gas to be treated, is injected into the outlet of the combustion catalyst layer 8 through the exhaust gas branch pipe 10 that penetrates the combustion catalyst layer 8 of the catalytic combustion type auxiliary burner 4, and the catalytically burned auxiliary gas is injected. The fuel is mixed with the high temperature combustion exhaust gas and heated. The combustible components contained in the low-calorie exhaust gas c heated in this way are completely combusted in the gas phase to generate combustion exhaust gas having a temperature higher than that of the combustion gas in the catalytic combustion. This combustion exhaust gas temperature is 750 ° C or higher, preferably 800 to 1000 ° C. Within this range, the amount of NOx produced is 10 to 20.
It can be suppressed to ppm or less. Then, the exhaust gas pipe 11 is added to the incinerator 1 heated to, for example, 650 ° C. or higher, preferably 700 ° C. or higher by the high temperature combustion exhaust gas.
After that, the rest of the low-calorie exhaust gas c, which is the gas to be treated, is introduced, and the combustible components in the low-calorie exhaust gas c are diluted and heated with the high-temperature exhaust gas to undergo low-temperature gas phase combustion. At this time, the residence time in the combustion furnace 1 is preferably 0.5 to 1 second or longer. After the combustion process, the detoxified exhaust gas is subjected to heat recovery by the waste heat recovery boiler 2 in the downstream, and is then released into the atmosphere through the chimney 3.

According to this embodiment, a portion of the gas to be treated (low-calorie exhaust gas c) is injected to the outlet of the combustion catalyst layer 8 of the auxiliary burner 4 and burned, so that it is difficult to self-burn. Even if the exhaust gas is, the auxiliary fuel is heated by the catalytically burned high-temperature exhaust gas and self-combusts to generate a higher-temperature combustion exhaust gas. Therefore, the high temperature exhaust gas can secure the temperature required for the direct combustion of the remaining gas to be treated. In this way, a part of the gas to be treated can function as the conventional auxiliary fuel, so that the consumption amount of the auxiliary fuel can be reduced. Further, along with this, the required amount of catalyst can be reduced.

According to this embodiment, the catalytic combustion of the auxiliary fuel a and the partial gas phase combustion of the low-calorie exhaust gas c as the gas to be treated are combined to act as an auxiliary combustion burner, so that all auxiliary combustion is performed. Since the fuel a can be catalytically burned at a relatively low temperature, the thermal N can be avoided by avoiding an extremely high temperature.
Generation of Ox can be reduced. Further, since the gas to be treated containing the catalyst poisoning component is introduced into the downstream of the combustion catalyst layer 8, it is possible to prevent the activity of the catalyst from being lowered and to perform the stable exhaust gas treatment for a long period of time.

Since the gas to be treated is originally low in calories, high temperature combustion can be avoided and NOx generation can be suppressed. Further, if the temperature of the catalytic combustion section is maintained at a predetermined temperature, the temperature of the gas phase combustion section may rise to some extent, so that the amount of cooling air can be significantly reduced. In this embodiment, the amount of the auxiliary fuel a introduced into the auxiliary combustion burner 4 is
The temperature is controlled based on the outlet temperature of the combustion catalyst layer 8 and the temperature inside the combustion furnace 1, and the amount of air b introduced is controlled based on the amount of auxiliary fuel introduced and the outlet temperature of the air preheater 7. Further, the amount of a part of the to-be-processed gas injected to the outlet of the combustion catalyst layer 8 of the auxiliary combustion burner 4 is controlled based on the combustion ambient temperature of the to-be-processed gas combusted at the outlet of the combustion catalyst layer 8.

In the present embodiment, the gas to be treated does not contain a catalyst poisoning component, and the calorific value is, for example, 300 to 400 Kca.
When it is 1 / m ³ · N or more, it can be used as a substitute for auxiliary fuel. In this case, auxiliary fuel is unnecessary. Although the air preheater 7 is provided in the combustion furnace 1 in the present embodiment, it may be separately provided by utilizing an electric heater or another heat source. Further, although the boiler device is used as the means for recovering waste heat, any other means may be used as long as it can recover heat. Further, the waste heat recovery device may be omitted.

FIG. 2 is an enlarged explanatory view of the essential parts of another embodiment of the present invention. This device has a large capacity of the catalytic combustion type auxiliary combustion burner, and is provided with an annular passage 12 for introducing a part of the gas to be treated in the peripheral portion of the combustion catalyst layer 8 to provide a larger combustion furnace. Applied. In the present embodiment, it is preferable to provide a flame holding plate 13 in the peripheral portion of the combustion catalyst layer 8 to have a flame holding effect.

Also in this embodiment, the same effect as the above embodiment can be obtained.

[0020]

According to the invention described in claim 1 of the present application, the auxiliary combustion burner is a catalytic combustion type auxiliary combustion burner, and a part of the gas to be treated is injected into the combustion catalyst layer outlet of the catalytic combustion type auxiliary combustion burner. By providing the pipe, a part of the gas to be treated can function as an auxiliary fuel, so that the amount of auxiliary fuel used can be significantly reduced. Further, it is possible to avoid contact between the catalyst poisoning component in the gas to be treated and the combustion catalyst to prevent the catalyst activity from being lowered, and to perform stable exhaust gas treatment for a long period of time.

According to the second aspect of the present invention, by injecting a part of the gas to be processed to the combustion catalyst layer outlet of the auxiliary combustion burner, a part of the gas to be processed can function as an auxiliary fuel. The amount of auxiliary fuel used can be reduced. Further, it is possible to avoid contact between the gas to be treated containing the catalyst poisoning component and the combustion catalyst to prolong the life of the catalyst.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an exhaust gas treatment apparatus showing an embodiment of the present invention.

FIG. 2 is a partially enlarged explanatory view of another embodiment of the present invention.

FIG. 3 is an explanatory diagram of a conventional technique.

FIG. 4 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

1 ... Combustion furnace, 2 ... Waste heat recovery boiler, 3 ... Chimney, 4 ... Auxiliary burner, 5 ... Auxiliary fuel piping, 6 ... Air piping, 7 ... Air preheater, 8 ... Combustion catalyst layer, 9 ... Mixing section, 10 ... Exhaust gas branch piping, 11 ... Exhaust gas piping, 12 ... Ring path, 13 ... Flame holding plate.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B01D 53/94

Claims (2)

[Claims] 1. A method for treating exhaust gas containing a catalyst poisoning component using an exhaust gas treatment device having a combustion furnace equipped with a catalytic combustion type auxiliary combustion burner, the method comprising: Combustion at a temperature higher than that of the combustion gas at the time of catalytic combustion, which is generated by introducing a part of the gas to be processed and combusting a part of the gas to be processed in the combustion gas at the time of catalytic combustion of the auxiliary fuel An exhaust gas treatment method, characterized in that the remaining gas to be treated is introduced into the gas and burned. 2. A treatment apparatus for exhaust gas containing a catalyst poisoning component, comprising: a combustion furnace provided with an auxiliary combustion burner; and an exhaust gas introduction pipe for introducing exhaust gas into the combustion furnace. An exhaust gas treating apparatus comprising a burner, a branch pipe being provided in the exhaust gas introducing pipe, and an outlet of the branch pipe being opened to a catalyst layer outlet of the catalytic combustion type auxiliary combustion burner.