JP2005066407A - Catalyst-packed apparatus in exhaust gas treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst-packed apparatus in an exhaust gas treatment apparatus, which is arranged at such a position that exhaust gas is made to flow downward from above in the exhaust gas treatment apparatus and in which untreated gas is prevented from leaking through a gap between its inner wall and a honeycomb catalyst unit to be expanded at high temperature. <P>SOLUTION: This catalyst-packed apparatus is constituted so that the honeycomb catalyst unit is arranged on a support installed on the inner wall of this catalyst-packed apparatus. At least a packed layer of particulate matter having 0.5-5 mm average particle size is formed in the gap between the honeycomb catalyst unit and the inner wall of this catalyst-packed apparatus. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a catalyst filling device constituting an exhaust gas treatment device, and in particular, a catalyst filling capable of preventing leakage of untreated gas due to expansion of a gap between a honeycomb catalyst unit and an inner wall of the device at a high temperature. It relates to the device.
[0002]
[Prior art]
In the process of treating coke oven exhaust gas, gas discharged from various chemical factories, city-type cleaning facilities, city-type water purification facilities, sludge treatment facilities, etc., a device filled with a catalyst such as titanium (catalyst filling) The exhaust gas is passed through the apparatus), and harmful components such as organic gas contained in the exhaust gas are decomposed and removed.
[0003]
In the above catalyst filling device, the exhaust gas and the catalyst come into contact with each other and an exothermic reaction occurs. Therefore, the temperature rises during operation, and the metal component of the device undergoes thermal expansion. Along with this, for example, gaps may be generated between members, plastic deformation may occur in the members, and various problems that cannot occur at normal temperature may occur.
[0004]
As a technique intended to solve these problems, Patent Document 1 discloses that a gas leaking portion is gas-sealed with a metal touch so that it is kept at a normal temperature by a reactor internal component that is in contact with high-temperature exhaust gas and a heat insulating material. A seal structure is disclosed in which a high-concentration exhaust gas of nitrogen oxides can be prevented from passing through a gap provided by a difference in thermal expansion with respect to a dripped reactor casing.
[0005]
In Patent Document 2, a sealant accommodating space is formed in one of the outer periphery of the catalyst support frame and the inner periphery of the outer casing, and an elastic sealant is inserted, and a pressure holding member is attached to the other side. There has been disclosed a sealing mechanism devised so that a stable exhaust gas sealing effect can be obtained even when the catalyst support frame is stretched and deformed by heat by keeping the stretchable sealing material in a compressed state.
[0006]
Further, Patent Document 3 includes guide means for movably supporting the pallet as a structure including a housing of the catalyst pallet group so that the flow of the gas to be processed does not cause a short circuit due to cylinder slippage. Has been proposed that has flanges provided on the left and right sides of the pallet that can slide with the guide means, and further has flanges on the front and rear of the pallet that abut the edges of the housing.
[0007]
These techniques solve the problems that occur because the constituent members of the catalyst filling device such as the catalyst support frame and the support base are metal members that easily expand at high temperatures.
[0008]
Incidentally, as described above, in the catalyst filling device, an exothermic reaction occurs due to contact between the exhaust gas and the catalyst, so that the temperature at the catalyst outlet is generally higher than that at the catalyst inlet. Therefore, in the case of a catalyst filling device configured such that the exhaust gas flow is directed from the top to the bottom, a support base (made of metal) located near the catalyst outlet causes thermal expansion to expand the inner wall of the device. On the other hand, a catalyst such as alumina disposed inside the apparatus, or a ceramic fiber filled in the gap between the catalyst and the inner wall of the apparatus has a smaller coefficient of thermal expansion than the above-mentioned metal support base, so that even at high temperatures, Since it does not expand and a difference in thermal expansion occurs, voids may be generated.
[0009]
For example, the exhaust gas in the production of (meth) acrylic acid or (meth) acrylic acid ester will be described. Since the exhaust gas contains a large amount of organic components, the amount of heat generated during the treatment is large, and the catalyst inlet temperature is about 320 ° C. On the other hand, the catalyst outlet temperature reaches 700 ° C.
[0010]
Simulating such a situation, for example, assuming that a square austenitic stainless steel support base having a side of 2.6 m is heated from room temperature to 700 ° C., the average thermal expansion coefficient of austenitic stainless steel is 17. Since it is 1 × 10 ⁻⁶ m / m ° C., the support base extends about 30 mm in the vertical and horizontal directions. On the other hand, a ceramic catalyst having an average coefficient of thermal expansion of about 1.71 × 10 ⁻⁶ m / m ° C. of the same size extends only about 3 mm in the vertical and horizontal directions. When the support base is 700 ° C., the support base becomes one size larger, and a difference of about 27 mm occurs.
[0011]
As described above, due to the remarkable difference between the thermal expansion of the metal support and the thermal expansion of the catalyst or the like, it is conceivable that the gap between the inner wall of the apparatus and the catalyst or the like is significantly expanded at a high temperature. Even when the ceramic fiber or the like is densely filled in the gap in advance, the ceramic fiber has a small coefficient of thermal expansion as described above, and thus it is conceivable that a void is generated between the ceramic fiber layer and the inner wall of the apparatus. Therefore, in order to reliably prevent leakage of untreated gas, it is considered necessary to consider leakage prevention from the gap.
[0012]
In Patent Document 4, it is shown that in the space between the catalyst layer and the reactor wall surface, a granular catalyst is filled on a wire mesh, but the pressure loss ratio cannot be maintained high depending on the size of the granular catalyst. Or may not necessarily be excellent in fluidity.
[0013]
[Patent Document 1]
Japanese Patent No. 2587422 [Patent Document 2]
JP-A-8-108044 [Patent Document 3]
JP 2002-239345 A [Patent Document 4]
Japanese Patent Laid-Open No. 57-56026
[Problems to be solved by the invention]
The present invention has been made in view of such circumstances, and even when the gap between the honeycomb catalyst unit and the inner wall of the apparatus is expanded at a high temperature, the leakage of untreated gas can be reliably prevented, and the exhaust gas treatment can be performed. An object of the present invention is to provide a catalyst filling device capable of increasing the efficiency.
[0015]
[Means for Solving the Problems]
The catalyst filling device in the exhaust gas treatment device according to the present invention is an exhaust gas treatment device in which a honeycomb catalyst unit is disposed on a support base attached to the inner wall of the catalyst filling device, and the exhaust gas flow is directed from top to bottom. In the catalyst filling apparatus according to claim 1, there is a feature in that at least a packed layer made of a granular material having an average particle diameter of 0.5 to 5 mm is formed in a gap between the honeycomb catalyst unit and the inner wall of the apparatus.
[0016]
As the granular material, it is preferable to use a ceramic product which is rich in fluidity, chemically stable and easy to handle, and preferable ceramics include, for example, γ-alumina. Furthermore, it is also effective to fill a granular material that supports one or more selected from the group consisting of Pt, Pd, and Rh to give a catalytic function.
[0017]
Further, when the apparatus of the present invention is used in a situation where the inlet temperature of the honeycomb catalyst unit is 300 ° C. or higher during exhaust gas treatment and the outlet temperature of the honeycomb catalyst unit is 100 ° C. or higher than the inlet temperature, The effect can be fully exhibited.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Under the circumstances as described above, the present inventors have provided a catalyst packing in which a honeycomb catalyst unit is disposed on a support base attached to an inner wall of a catalyst charging device, and an exhaust gas flow is directed from top to bottom. In the apparatus, even when the gap between the honeycomb catalyst unit and the inner wall of the apparatus is widened at a high temperature and a gap is generated, an apparatus that can more reliably prevent untreated gas from leaking from the gap and increase the exhaust gas treatment rate. We have studied from various angles to realize it.
[0019]
As a result, it has been found that a granular material packed layer made of granular materials having an average particle size of 5 mm or less may be formed in the gap between the honeycomb catalyst unit and the inner wall of the catalyst charging device, and the present invention has been conceived. With such a structure of the catalyst filling device, even when the gap is widened and the gap is generated, the granular material flows according to the enlargement of the gap and closes the gap. The gap can be maintained in a high pressure loss state, and leakage of untreated gas can be prevented.
[0020]
When the average particle size is too large, the pressure loss ratio with the catalyst layer cannot be kept high, and the untreated gas tends to leak. Therefore, a granular material having an average particle size of 5 mm or less is used. A granular material of 4 mm or less is preferable. On the other hand, if the average particle size is too small, the fluidity is lowered, and the effects of the present invention may not be sufficiently exhibited. In addition, when such a granular material having an average particle size that is too small is used, the granular material may fall out of the gap between the honeycomb catalyst unit and the inner wall of the apparatus. Therefore, a granular material having an average particle size of 0.5 mm or more is used. Preferably, a granular material having an average particle diameter of 1.0 mm or more is used.
[0021]
The granular material is preferably filled so as to have a filling density of 0.5 to 1.5 g / cm ³ .
[0022]
In addition, as the granular material, those having various shapes such as a crushed material, a cylindrical material, a polygonal material, and a spherical material can be used, but in order to ensure fluidity at a high temperature, the spherical material is used. Recommended to use.
[0023]
The material of the granular material is not particularly limited, but it is recommended to use a ceramic that is easy to handle and has fluidity at high temperatures. Examples of the ceramic include oxides of aluminum, titanium, silicon, zirconium, cerium, tungsten, etc. Among them, if γ-alumina is used, it is chemically stable even at high temperatures, and is fluid. Is also preferable.
[0024]
It is preferable to use a catalyst that exhibits a catalytic action as the particulate matter because the exhaust gas can be purified even when the exhaust gas flows into the particulate-filled bed. Examples of the granular material having such a function include one or more metals having an action as an exhaust gas purification catalyst such as Pt, Pd, Rh, Fe, Co, Ni, Mn, Cu, and V, for example, Those supported on a ceramic carrier may be mentioned. In particular, in order to effectively decompose the volatile organic component in the exhaust gas, it is preferable to use one in which one or more selected from the group consisting of Pt, Pd and Rh are supported on the surface of the γ-alumina granular material.
[0025]
The granular material packed bed is preferably packed so that the average particle size of the granular material becomes larger in the direction of the exhaust gas flow. In this way, the particles are packed so that the average particle size of the particles increases in accordance with the direction of the exhaust gas flow, the particles near the catalyst inlet have a small average particle size, and the particles near the wire mesh have a large average particle size. By doing so, it is possible to prevent the particulate matter from dropping out from the gaps between the wire mesh and the ceramic wool while maintaining a high pressure loss ratio. In addition, the gap generated between the ceramic wool and the inner wall of the apparatus is filled quickly, and leakage of untreated gas can be reliably suppressed.
[0026]
As a more specific catalyst filling device of the present invention, in the gap between the honeycomb catalyst unit and the inner wall of the device,
(1) A structure in which a ceramic fiber densely packed layer and the granular material packed layer are formed in order from the bottom on the support base,
(2) If the structure in which the ceramic fiber densely packed layer, the metal net, and the granular material packed layer are formed in order from the bottom is adopted on the support base, the granular material packed layer can be stably held. preferable.
[0027]
Hereinafter, the present invention will be described more specifically with reference to the catalyst filling apparatus illustrated in FIGS. 1 and 2, but the present invention is not limited to the illustrated examples.
[0028]
FIG. 1 is a cross-sectional explanatory view showing an example of a catalyst filling device constituting the exhaust gas treatment device. A support base 6 is attached in a rectangular parallelepiped cylindrical or cylindrical catalyst filling device 1, and the honeycomb catalyst unit 2 is disposed on the support base 6 via a wire mesh 5.
[0029]
As the support base, a material such as an iron alloy such as iron or stainless steel can be used, and a structure having an arbitrary structure such as a grid bar type or a multi-beam type can be used. In addition to the method of fixing to the inner wall of the apparatus by welding, bolts, nuts, or the like, the mounting can also be performed by hanging on a hook or the like attached to the inner wall of the apparatus.
[0030]
Further, when the support base 6 having a large gap is used so as not to increase the pressure loss, if the catalyst unit 2 is arranged on the support base 6 after the metal mesh 5 having a small mesh is laid, for example, the structural unit of the catalyst unit 2 Even if it is comparatively small, there is no fear of dropping off, which is preferable. Although not shown, a pressing tool may be disposed on the upper part of the honeycomb catalyst unit 2.
[0031]
In the gap between the honeycomb catalyst unit 2 and the inner wall of the catalyst filling device 1 in FIG. 1, the ceramic fiber densely packed layer 4, the granular material packed layer 3, and the granular material packed layer 3 are pressed onto the support base 6 and the wire mesh 5. The ceramic fiber densely packed layer 4 is formed in order from the bottom.
[0032]
In the present invention, it is assumed that a honeycomb catalyst having sufficient strength, contact efficiency, and pressure resistance is used. The honeycomb-shaped catalyst may have a “honeycomb” shape as well as a “lattice-like” or “corrugated (bellows-like)” shape, and a hexagonal, square, or triangular opening shape. Including those having The catalyst is not particularly limited in terms of size, pore diameter, specific surface area, and the like, and a honeycomb-like catalyst manufactured by a known method can be used without limitation.
[0033]
What is necessary is just to select the material of the said catalyst suitably according to to-be-processed gas. For example, when applied to treatment of exhaust gas containing a volatile organic component (VOC), a metal catalyst such as Pt, Pd, Rh, Fe, Co, Ni, Mn, Cu, and V having high oxidative decomposition performance for the component, For example, what is supported by about 0.01 to 3% by mass on a carrier made of ceramic may be used. These metal catalysts can be used alone or in combination of two or more in any combination. Among the above catalysts, Pt, Pd, and Rh are desirable because they have particularly excellent resolution for VOC and can maintain a high level of catalytic activity for a long period of time.
[0034]
Examples of a preferable carrier for supporting the catalyst component include alumina, titanium oxide, silicon oxide, zirconia, and cerium oxide.
[0035]
As the ceramic fiber, a commercially available product such as alumina or silica may be used.
[0036]
The method for filling the catalyst in the honeycomb catalyst unit 2 of the present invention is also not particularly limited. As shown in the examples described later, a cell filled with a plurality of catalysts in addition to arranging the rectangular parallelepiped cylindrical catalysts in the vertical and horizontal directions. The structure which arranges two or more.
[0037]
In order to stabilize the granular material packed layer shown in FIG. 1 more reliably, a metal net 7 is laid on the ceramic dense packed layer 4 as shown in FIG. 2, and the granular packed layer 3 is formed thereon. Good. As the metal net 7, one made of an iron alloy such as iron or stainless steel can be used.
[0038]
If the catalyst filling device is configured as described above, even when the catalyst outlet temperature is higher than the catalyst inlet temperature by 100 ° C. or more, it is possible to more reliably prevent the untreated gas from leaking and increase the exhaust gas treatment rate. Even when the inlet temperature of the catalyst unit is 300 ° C. or higher during exhaust gas treatment and the catalyst outlet temperature is higher than the inlet temperature by 100 ° C. or higher, the effect of the present invention can be sufficiently achieved. .
[0039]
When the exhaust gas treatment apparatus is configured by incorporating the catalyst filling apparatus of the present invention, a gas filter is provided, or a liquid catalyst tank is additionally provided to remove other harmful components. It is also effective to install a heater in advance to heat the exhaust gas according to the characteristics, or to install a heat exchanger in order to reuse the waste heat after treatment for heating the exhaust gas. Also, in order to remove multiple harmful components, multiple catalyst filling devices filled with different types of catalysts are arranged in series, and in order to operate continuously, catalyst filling devices filled with the same type of catalyst are arranged in parallel. However, the line may be switched periodically by an automatic valve.
[0040]
When the VOC is processed, the space velocity of the catalyst is generally set to 10,000 to 50,000 Hr- ¹ . Moreover, it is preferable that the pressure loss ratio of the granular material to the honeycomb catalyst in the present invention is twice or more.
[0041]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention.
[0042]
<Invention Example 1>
The model gas which assumed the waste gas generated in the processing process of the waste liquid produced in the (meth) acrylic acid and (meth) acrylic acid ester manufacturing process was processed in the exhaust gas processing process including the process shown in FIG.
[0043]
As shown in FIG. 4 (cross-sectional explanatory view), on a grid bar type support base 6 made of austenitic stainless steel attached in an austenitic stainless steel square reactor (catalyst filling apparatus 1) having a side of 2594 mm, After laying the wire mesh (made of SUS304) 5, first, 17 honeycomb catalysts 2 each supporting a noble metal (Pt, Pd) and having a size of 150 mm square and a height of 50 mm were arranged one by one in 17 columns. At this time, the gap between the honeycomb catalyst 2 and the device inner wall 8 was 22 mm. And as shown in FIG. 4, a blanket-like ceramic fiber 4 (made by Isolite Kogyo Co., Ltd., trade name: Isowool) is filled in the gap with a packing density of 0.25 g / mL (about 2.5 times the unused state), high The demister 7 made of SUS304 was placed on the top.
[0044]
Next, the 2nd to 5th stage honeycomb catalyst 2 was installed in the same manner as the first stage, and then spherical γ-alumina (average particle size: 3 mm) between the honeycomb catalyst 2 and the inner wall 8 of the apparatus [Sumitomo “NKH3-24”] 3 manufactured by Chemical Industry Co., Ltd. was filled to a position 25 mm below the upper surface of the uppermost (fifth) honeycomb catalyst. Thereafter, ceramic fibers 4 similar to those described above were closely packed up to the upper surface of the honeycomb catalyst 2.
[0045]
In the exhaust gas treatment process of FIG. 3 equipped with such a catalyst filling device, an exhaust gas containing CO: 5000 ppm, CO ₂ : 3.0%, propylene: 1400 ppm, and propane: 2800 ppm has a temperature at the catalyst inlet of 350 ° C. After being heated by the heater 12 in advance, the gas is flowed from the upper part of the catalyst filling device 11 under the conditions of gas flow rate: 570 m ³ (normal) / min, space velocity (SV): 21000 Hr ⁻¹ to remove the CO and the like. Processed. As a result, the catalyst outlet temperature reached 700 ° C., and CO in the treated gas was 37 ppm, CO ₂ was 4.8%, propylene was 2 ppm, and propane was 5 ppm.
[0046]
<Invention Example 2>
Exhaust gas treatment was performed in the same manner as in Example 1 of the present invention except that an alumina sphere (average particle size 3 mm) carrying a noble metal (Pd) was used instead of the sphere γ-alumina. . As a result, the catalyst outlet temperature reached 700 ° C., and CO in the treated gas was reduced to 18 ppm, CO ₂ was 4.8%, propylene was 1 ppm, and propane was reduced to 3 ppm.
[0047]
From the comparison between the present invention example 1 and the present invention example 2, it is possible to treat the exhaust gas flowing into the gap between the honeycomb catalyst and the inner wall of the apparatus if the particulate material carrying a noble metal (Pd) having a catalytic function is used. It can be seen that harmful components in the exhaust gas can be reduced more efficiently.
[0048]
<Comparative Example 1>
Except that the gap between the honeycomb catalyst unit 3 and the inner wall of the apparatus 1 was filled only with the blanket-shaped ceramic fiber up to the upper surface of the honeycomb catalyst so that the filling density was 0.25 g / mL, the same as in the above-mentioned Example 1 of the present invention. The exhaust gas was treated.
[0049]
As a result, the catalyst outlet temperature reached 700 ° C., and CO in the treated gas was 44 ppm, CO ₂ was 2.8%, propylene was 10 ppm, and propane was 15 ppm.
[0050]
<Comparative example 2>
Exhaust gas was treated in the same manner as in Invention Example 1 except that spherical γ-alumina having an average particle diameter of 8.5 mm was used.
[0051]
As a result, the catalyst outlet temperature reached 700 ° C., and CO in the treated gas was 42 ppm, CO ₂ was 2.8%, propylene was 6 ppm, and propane was 10 ppm.
[0052]
From the comparison between these comparative examples and the above inventive examples 1 and 2, it can be seen that the catalyst filling apparatus of the present invention should be employed in order to further reduce the untreated gas. In the above embodiment, the CO ₂ concentration is higher than that before the treatment because CO and organic matter in the untreated gas are treated and converted to CO ₂ .
[0053]
【The invention's effect】
According to the present invention, it is possible to reliably prevent the untreated gas from leaking from the voids caused by the difference in thermal expansion between the catalyst and the like at high temperature and the structural member. In particular, in a catalyst filling device configured so that the exhaust gas flow is directed from the top to the bottom, even if the gap between the honeycomb catalyst unit and the inner wall of the device is significantly expanded due to the expansion of the catalyst support base, the leakage of untreated gas And the exhaust gas treatment rate can be increased.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of the present invention.
FIG. 2 is a schematic sectional view showing another example of the embodiment of the present invention.
FIG. 3 is a schematic process diagram showing a part of an exhaust gas treatment process employed in an example.
FIG. 4 is a schematic cross-sectional view showing a catalyst filling apparatus according to an example of the present invention used in Examples.
[Explanation of symbols]
1, 11 Catalyst filling device 2 Honeycomb catalyst unit 3 Granule packed bed 4 Ceramic dense packed bed (ceramic fiber)
5 Wire mesh 6 Support stand 7 Metal mesh (Demister)
8 Inner wall 12 Heater 13 Heat exchanger 14 Blower

Claims (5)

A catalyst filling device in which a honeycomb catalyst unit is arranged on a support base attached to an inner wall of the catalyst filling device, and an exhaust gas flow is directed from the top to the bottom, in the gap between the honeycomb catalyst unit and the inner wall of the device. A catalyst filling device in an exhaust gas treatment device, wherein at least a packed bed made of a granular material having an average particle size of 0.5 to 5 mm is formed. The catalyst filling apparatus according to claim 1, wherein the granular material is ceramic. The catalyst filling apparatus according to claim 2, wherein the ceramic is γ-alumina. 3. The catalyst filling apparatus according to claim 2, wherein the ceramic is one in which at least one selected from the group consisting of Pt, Pd, and Rh is supported on the surface of the γ-alumina granular material. Any one of claims 1 to 4, wherein the honeycomb catalyst unit is used in a situation in which an inlet temperature of the honeycomb catalyst unit is 300 ° C or higher and an outlet temperature of the honeycomb catalyst unit is 100 ° C or higher than the inlet temperature during exhaust gas treatment. The catalyst filling apparatus according to claim 1.

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