JP6918351B2 - Ceramic member and flow path member - Google Patents

Description

The present invention relates to a ceramic member used for a flow path member or the like.

The flow path member disclosed in Patent Document 1 includes a container and first to third layers housed in the container. The first layer contains an irregularly oriented ceramic medium, the second layer consists of components containing catalytically active metal placed on the surface of the ceramic pellets, and a third layer. Layer contains a floor support medium. A fluid flows in the container while sequentially contacting each medium of the first to third layers. The ceramic medium constituting the first layer is produced by extrusion-molding a raw material made of clay or the like and then firing it, and has a function of uniformly dispersing and diffusing a fluid.

Special Table 2012-517347

By the way, when the flow path member is applied to, for example, an oil refinery, the ceramic medium is exposed to a high temperature and high pressure environment and is subjected to a thermal shock due to repeated use. On the other hand, since the ceramic medium is sintered after extrusion molding, stress tends to be concentrated on a portion having an internal / external density difference, and cracks may occur due to thermal shock. If cracks occur, the contact resistance of the surface of the ceramic medium in contact with the fluid increases, the pressure loss increases, and the fluid dispersion function of the medium may be hindered.

The present invention has been completed based on the above circumstances, and an object of the present invention is to provide a ceramic member in which cracks are unlikely to occur and a flow path member filled with the ceramic member.

The ceramic member of the present invention is characterized in that it is an extruded sintered body containing a clay binder and a low thermal expansion material containing lithium aluminosilicate.

According to the present invention, since the low thermal expansion material containing lithium aluminosilicate can relieve stress due to thermal expansion and thermal shock, it is possible to obtain a ceramic member in which cracks are unlikely to occur even in an extruded sintered body. ..

It is the schematic of the flow path member in an embodiment.

Preferred embodiments of the present invention are described below.
The ceramic member may be formed into a tubular shape. According to this, since the thermal stress can be dispersed in the circumferential direction, the occurrence of cracks can be satisfactorily suppressed.

The average particle size of the low thermal expansion material is preferably # 46 to # 400. When the average particle size of the low thermal expansion material is within the above range, the moldability at the time of extrusion molding is good. If the average particle size is larger than # 46, it may damage the molding machine, which is not preferable. If the average particle size is smaller than # 400, the frictional resistance with the molding machine may increase and the moldability may deteriorate. ..

The ceramic member contains a composition of _{SiO 2} 65 to 75%, Al ₂ O ₃ 18 to 27%, and Li ₂ O 1 to 1.3 % in terms of oxide weight percentage. If the composition of the oxide is within the above range, the ceramic member can be made into a ceramic member which is less likely to crack even in an environment where it is repeatedly subjected to thermal shock.

As for the ceramic member, the low thermal expansion material may contain petalite. Petalite is available at a relatively low cost, which is advantageous in terms of cost.

It is preferable that the mixing ratio of the raw materials of the ceramic member is 50 to 90% of the clay binder, 10 to 50% of the low thermal expansion material, and 0 to 30% of the clay in terms of weight percentage. With a blending ratio within this range, a ceramic member having good moldability can be obtained. In particular, when the low thermal expansion material is smaller than 10%, the effect of suppressing the occurrence of cracks is weakened, and when the low thermal expansion material is larger than 50%, the effect reaches a plateau and is disadvantageous in terms of cost.

The ceramic member may contain clay. The inclusion of clay improves moldability during extrusion molding. However, if the clay content is larger than 30%, the viscosity becomes too strong and the moldability is deteriorated, which is not preferable.

The ceramic member is filled in the flow path member, has a surface in contact with a fluid flowing in the flow path member, and has a porosity of 4% or less. When the surface of the ceramic member comes into contact with the fluid and gets wet, and then is dried, and the cycle of repeating this wetting and drying is performed, it is necessary to increase the drying efficiency (drying rate), so the porosity is 4% or less. be. On the other hand, if the porosity is 4% or less, there is a concern that cracks are likely to occur. However, in the case of this ceramic member, since a low thermal expansion material of lithium aluminosilicate is contained, cracks are less likely to occur, so that pores are likely to occur. Even if the rate is 4% or less, it can be applied to the flow path member without any trouble.

The ceramic member preferably has a porosity of 1% or less. When the porosity is 1% or less, the drying efficiency of the ceramic member can be further improved.

It is preferable that the flow path member in which the ceramic member is filled is set so that the porosity in the filling space of the ceramic member is 45 to 65%. If the porosity is in this range, the pressure loss can be suppressed to a small value. In addition, it is possible to suppress an increase in the weight of the ceramic member. On the other hand, if the porosity is larger than 65%, there is a concern that the moldability at the time of extrusion molding deteriorates, and if the porosity is smaller than 45%, the pressure loss becomes large, which is not preferable.

<Embodiment>
The ceramic member of the embodiment is a sintered body of an extruded body containing a clay binder, a low thermal expansion material, and clay. Of these, clay is not essential, but may be included in order to improve moldability during extrusion molding.

The clay-based binder is commercially available as a raw material for general ceramics and has plasticity. The clay binder is made from feldspar, pottery stone, and clay at least , and contains silica (silicon oxide) and alumina (aluminum oxide) as at least components.

The low thermal expansion material is mainly composed of lithium aluminosilicate (lithium-containing composite oxide, general formula Li ₂ O, Al ₂ O ₃ , nSiO ₂ ), and suppresses thermal expansion during sintering. It has a good low coefficient of thermal expansion, and may have a negative coefficient of thermal expansion, not limited to positive. The low thermal expansion material, petalite _{(Li 2 0 · Al 2 O} 3 · 8SiO 2), β- eucryptite _{(Li 2 0 · Al 2 O} 3 · 2SiO 2), β- spodumene _{(Li 2} 0 · Al 2 O ₃ · 4SiO ₂₎ may be used alone or two or more of. Preferably, after sintering, a β-quartz solid solution (bilgilite) is precipitated as the main crystal phase. Crystals of β-quartz solid solution have near zero or negative thermal expansion.

Petalite is preferred as the low thermal expansion material. This is because petalite can be obtained at a relatively low price and can be stably supplied. Further, the coefficient of thermal expansion may be adjusted by combining one or both of β-eucryptite and β-spojumen together with petalite as the low thermal expansion material, and if lithium aluminosilicate is the main material, There is no particular limitation.

The average particle size of the low thermal expansion material is preferably adjusted to # 46 to # 400 (average particle size (median diameter D50) 340 to 37 μm) in consideration of the influence on the extruder. If the average particle size is larger than # 46 (average particle size 340 μm), it is as if molding contains gravel, which may accelerate damage to the extruder. On the other hand, if the average particle size is smaller than # 400 (average particle size 37 μm), the frictional resistance of the extruder becomes large and it is difficult to mold.

Clay is a soil containing clay minerals as a main component, and is not particularly limited, but is obtained and used independently of the clay contained in the clay binder. Since this clay is easily plastically deformed, it may be added, for example, when the plasticity of the molded product cannot be sufficiently ensured only by the clay binder alone.

As shown in FIG. 1, the ceramic member 20 (hereinafter, a reference numeral is given when it is related to FIG. 1, but the reference numeral is omitted when it is not particularly related) is a flow of a distillation column, a reaction column, or the like of a petroleum refining apparatus. It may be used as a filler in the road member 10. This type of ceramic member 20 is installed as a catalyst support material in the container 30 of the flow path member 10 on at least one of the upper and lower sides of the catalyst material. In the illustration, the upper layer 40 filled with the ceramic member 20, the intermediate layer 50 filled with the catalyst material, and the lower layer 60 filled with the ceramic member 20 are arranged in a stacked state in the container 30. Will be done.

The container 30 has an inflow portion 31 into which the fluid flows in at the upper end portion, and an outflow portion 32 in which the fluid flows out at the lower end portion. The ceramic member 20 and the catalyst material have a surface that comes into contact with the fluid flowing in the container 30, and the fluid selectively removes sulfur and the like by coming into contact with the surface of the catalyst material. Contrary to the case shown in the drawing, the inflow portion 31 may be provided at the lower end portion of the container 30, and the outflow portion 32 may be provided at the upper end portion of the container 30.

The ceramic member 20 has a fluid dispersion function in the upper layer 40 to uniformly disperse and diffuse the fluid toward the intermediate layer 50. Further, the ceramic member 20 is an extruded body having a constant cross-sectional shape in the axial direction, and here, it is molded into a cylindrical shape such as a substantially cylindrical shape. The axial end surface and the inner and outer peripheral surfaces of the ceramic member 20 are surfaces that come into contact with the fluid, and are surfaces that define the flow path of the fluid. Then, when the ceramic member 20 is filled in an irregular direction, the fluid dispersion function is properly exhibited.

By the way, since the ceramic member used for the flow path member receives a thermal shock by repeating the cycle of raising and lowering the temperature, there is a concern that cracks may occur. Here, if the ceramic member has a porosity of more than 4%, it was confirmed by a spalling test described later that cracks are unlikely to occur. It is considered that this is because the pores act as cushions to cushion the thermal shock.

On the other hand, if the porosity exceeds 4%, there is a problem that the drying time for drying the ceramic member as a filler for the next use becomes long. Therefore, in order to increase the drying efficiency (drying rate), it is necessary to suppress the porosity to 4% or less, and it is desired that cracks are still unlikely to occur even if the porosity is 4% or less.

In that respect, the ceramic member of the present invention contains a low thermal expansion material containing lithium aluminosilicate and is formed into a tubular shape so that cracks are extremely unlikely to occur even if the porosity is 4% or less. There is. More specifically, in the ceramic member, the porosity is suppressed to 1% or less, so that the drying efficiency is further improved and the occurrence of cracks is also suppressed. A ceramic member having a porosity of 1% or less can reduce the drying time as compared with a ceramic member having a porosity of 5%.

Further, in the stage before firing, the ceramic member is preferably blended with a clay binder at a ratio of 50 to 90%, a low thermal expansion material at 10 to 50%, and clay at a ratio of 0 to 30% as a weight percentage. .. If the amount of the low thermal expansion material is less than 10%, the crack suppressing effect may be diminished, and if the amount of the low thermal expansion material exceeds 50%, the effect may reach a plateau and a wasteful cost increase may occur. The ceramic member may further reduce the content of the low thermal expansion material so that the clay binder is 60 to 90%, the low thermal expansion material is 10 to 40%, and the clay is 0 to 30%. ..

The clay binder is preferably blended in a larger amount than each of the low thermal expansion material and the clay. The clay is preferably blended in consideration of moldability, and is preferably composed of 1 to 30% of the total blend.

Ceramic component, at a later stage calcination, in weight percent terms of oxide, the total oxides, SiO ₂ is 65~75%, _Al 2 _{O 3} is 18 to 27%, LiO ₂ is from 1 to 1.3% Is included in the ratio of. When Si, Al, and Li in the composition have a content in the above range in terms of oxide, a ceramic member that is less likely to crack due to repeated thermal shock can be obtained. In particular, a Li-containing material such as petalite is effective in suppressing the occurrence of cracks.

The porosity of the filling space of the ceramic member in the container of the flow path member (the measurement method will be described later) is preferably set to be 45 to 65%. If the porosity is in the range of 45 to 65%, the pressure loss of the fluid flowing in the upper layer in the container does not increase, and the filling weight is relatively light, so that the catalyst material in the intermediate layer is not easily crushed. be. If the porosity is larger than 65%, it is easily crushed during extrusion molding, and if the porosity is smaller than 45%, the pressure loss becomes large.

<Manufacturing method (samples 1 to 5)>
Each of the raw materials of Samples 1 to 5 was adjusted in the blending ratio shown in Table 1, stirred in a dry state for 5 minutes with a mixer, and mixed uniformly. Commercially available clay binders, petalite, and clay were used. In Table 1, the binder is an abbreviation for clay binder, and A to F are sources of raw materials.

Subsequently, water was added and mixed wet to adjust the hardness to be suitable for extrusion molding.
Next, the mixture was put into an extrusion molding machine, extruded into a long tubular shape, and the extruded long tubular body was cut to a predetermined length to obtain a tubular extruded material.
Then, the naturally dried extruded material was calcined at a temperature of 1200 to 1300 degrees. Since the sinterability of Samples 4 and 5 was improved, the combustion temperature of Samples 4 and 5 was lower than that of Samples 1 to 3. Table 2 shows the chemical composition (oxide equivalent) of Samples 1 to 5 after firing.

<Measurement method>
(Measurement of particle size distribution)
The particle size of petalite was measured using a laser diffraction / scattering particle distribution measuring device. Specifically, the sample is placed in a measuring device and ultrasonically dispersed in water for 3 minutes. Then, the aqueous solution in which the sample was dispersed was irradiated with a laser beam, and the particle size was measured. Here, when the average particle size of petalite is # 46 to # 400, the average particle size of petalite is 340 to 37 μm as the median diameter (D50).

(Porosity measurement)
The porosity was measured according to the boiling method of JIS-R2205. Specifically, the sample (ceramic member after firing) is dried in a dryer (105 ° C.), the mass when the constant amount is reached is set to the drying weight W ₁ (g), and the sample is placed under the water surface of the boiling tank. The sample was submerged, boiled for 3 hours or more, allowed to cool to room temperature, and the weight W ₂ (g) in water of the saturated sample was measured. The saturated water sample was taken out of the water, the surface was wiped with a compress to remove water droplets on the surface, and then the saturated water weight W ₃ (g) was measured. The porosity is calculated by the following formula.
Porosity (%) = (W _3- W ₁ ) / (W _3- W ₂ ) x 100

(Porosity measurement)
The porosity is the ratio expressed by "capacity of water / capacity of container (10L)" when a sample (ceramic member after firing) is filled in a 10L container by free fall and water is filled in the void. ..

(Air-cooled spalling test)
An air-cooled spalling test at 500 ° C. was performed in order to evaluate whether or not cracks were formed when the sample (ceramic member after firing) was repeatedly subjected to thermal shock. In the air-cooled spalling test, a keep temperature of 500 ° C., heating for 30 minutes, and air-cooling for 30 minutes were carried out for 10 cycles. After that, it was visually confirmed by a color check whether or not there was a crack, and the number of cracks was counted. In the color check, the sample is painted with an identification color such as red to make the cracks conspicuous.
Table 3 shows the physical property values of porosity and porosity, the results of the number of cracks generated, and the results of the pressure loss test when applied to the flow path member. In the comprehensive judgment in Table 3, "○" is a pass and "x" is a failure.

<Discussion>
As shown in Table 3, the ceramic members of Samples 4 and 5 had a small number of cracks, and in particular, Sample 5 had completely suppressed cracks. From this, it was found that the samples 4 and 5 are still strong against thermal shock even if the porosity is suppressed to 1% or less in consideration of the drying efficiency.
_{Sample 5 has a higher content of alumina (Al 2} O ₃ ) after firing than sample 4, and it is considered that this contributes to suppressing the occurrence of cracks. In view of this, it can be said that the content of alumina in the ceramic member after firing is more preferably 23 to 27% as a weight percentage.

Samples 4 and 5 have a porosity of 4% or less, preferably 1% or less, and are formed into a tubular shape to have a porosity of 45 to 65%. It was found that the member can be suitably used as a flow path member because it is excellent in drying efficiency during repeated use and does not cause a large pressure loss due to the difficulty of cracking.

<Other embodiments>
The ceramic member of the present invention is preferably formed into a tubular shape, but the concept of a tubular shape also includes a square tubular shape. Further, the ceramic member of the present invention is not limited to a tubular shape, and may be molded into, for example, a solid pellet shape.
The low thermal expansion material contained in the ceramic member of the present invention may be one that does not contain petalite and is composed of only one or both of β-eucryptite and β-spodium.
The flow path member of the present invention is not limited to the petroleum refining apparatus, and may be applied to various columns such as a deodorizing apparatus, a dehydrating apparatus, and a chromatography. Further, the fluid flowing in the flow path member is not limited to a liquid, but may be a gas. Further, the ceramic member of the present invention may contain a material other than a clay binder, a low thermal expansion material, and clay, or may have a function as a catalyst carrier.

10 ... Flow path member 20 ... Ceramic member

Claims (7)

Ri extruded sintered der comprising a clayey binder and a low thermal expansion material of the lithium aluminosilicate-containing,
It is filled in the flow path member, has a surface in contact with the fluid flowing in the flow path member, has a porosity of 4% or less, and has a porosity of 4% or less.
The clay binder contains at least feldspar, pottery stone, and clay as raw materials, and silica (silicon oxide) and alumina (aluminum oxide) as at least components.
The extruded sintered body is a ceramic member containing a composition of SiO 2 65 to 75%, Al ₂ O ₃ 18 to 27%, and Li _{2 O 1 to} 1.3% in terms of oxide weight percentage. The ceramic member according to claim 1, which is formed into a tubular shape. The ceramic member according to claim 1 or 2, wherein the low thermal expansion material has an average particle size of # 46 to # 400. The ceramic member according to any one of claims 1 to 3 , wherein the low thermal expansion material contains petalite. Claims that the mixing ratio of the raw materials is 50 to 90% of the clay binder, 10 to 50% of the low thermal expansion material, and 0 to 30% of clay (excluding those contained in the clay binder) in terms of weight percentage. Item 2. The ceramic member according to any one of Items 1 to 4. The ceramic member according to any one of 1 to 5, which has a porosity of 1% or less. A flow path member filled with the ceramic member according to any one of claims 1 to 6.
A flow path member characterized in that the porosity in the filling space of the ceramic member is set to be 45 to 65%.

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