CN111995435A - Method for filling pores in ceramic heat transfer element, and infiltration device - Google Patents
Method for filling pores in ceramic heat transfer element, and infiltration device Download PDFInfo
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- CN111995435A CN111995435A CN202010908440.2A CN202010908440A CN111995435A CN 111995435 A CN111995435 A CN 111995435A CN 202010908440 A CN202010908440 A CN 202010908440A CN 111995435 A CN111995435 A CN 111995435A
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Abstract
The invention discloses a method for filling pores of a ceramic heat transfer element, the ceramic heat transfer element and an infiltration device, and relates to the technical field of ceramics. The method for filling the pores of the ceramic heat transfer element comprises the following steps: immersing the ceramic heat transfer element in an impregnant under a vacuum condition for vacuum infiltration, and then heating and curing the ceramic heat transfer element with the impregnant filled in the air holes; wherein the infiltrant includes a binder and a thermally conductive filler. The ceramic heat transfer element is obtained by filling pores in the sintered ceramic heat transfer element by adopting the filling method, has no internal pore defect and surface crack defect, and has high thermal conductivity and compressive strength. The impregnation device is used for implementing the filling method, and can conveniently carry out vacuum impregnation work on the ceramic heat transfer element, so that air holes in the ceramic are effectively repaired.
Description
Technical Field
The invention relates to the technical field of ceramics, in particular to a method for filling pores of a ceramic heat transfer element, the ceramic heat transfer element and an infiltration device.
Background
At present, the air preheater used by a low-temperature waste heat recovery system in the petrochemical industry is generally made of metal materials, but when flue gas is corrosive, the air preheater made of traditional metal material heat transfer elements obviously cannot meet the use requirements. The mullite ceramic belongs to an inorganic nonmetallic material, and the chemical component of the mullite ceramic is acidic oxide SiO2Mainly resists the corrosion of all inorganic acids except hydrofluoric acid and high-temperature phosphoric acid. The mullite ceramic belongs to a structural ceramic material, has good chemical stability, high hardness, high temperature resistance and wear resistance, and is suitable for being used as a heat transfer element of an air preheater.
However, after the mullite ceramic heat exchange element blank is sintered, a large number of defects of open pores, closed pores and straight through pores exist, and particularly, the defects of the straight through pores cause the problems of medium mixing, leakage and the like of the heat exchanger, so that the application of the heat exchanger is seriously influenced. The conventional method for repairing defects is to improve the performance of the ceramic surface by glazing the ceramic surface and reduce through pores of the ceramic. The method has the disadvantages that (1) the thermal conductivity of the ceramic glaze is low, and the heat transfer capacity of the ceramic element is reduced due to glazing; (2) when the surface of the ceramic heat transfer element is glazed, the pressure in the through air hole of the ceramic is increased, and the glaze cannot completely fill the through air hole of the ceramic, so that the defect of the air hole in the sintered ceramic still exists; (3) the presence of a large number of pores also reduces the mechanical strength of the ceramic heat transfer element.
In view of this, the present application is specifically made.
Disclosure of Invention
The invention aims to provide a method for filling pores of a ceramic heat transfer element, which aims to repair the defects of the pores in the ceramic heat transfer element and increase the thermal conductivity and compressive strength of ceramic.
Another object of the present invention is to provide a ceramic heat transfer element which is free of through-air hole defects therein and has high thermal conductivity and compressive strength.
A third object of the present invention is to provide an infiltration apparatus for vacuum infiltration of a ceramic heat transfer element more conveniently to repair the internal pore defects of the ceramic heat transfer element.
The technical problem to be solved by the invention is realized by adopting the following technical scheme.
The invention provides a method for filling pores of a ceramic heat transfer element, which comprises the following steps: immersing the ceramic heat transfer element in an impregnant under a vacuum condition for vacuum infiltration, and then heating and curing the ceramic heat transfer element with the impregnant filled in the air holes; wherein the infiltrant includes a binder and a thermally conductive filler.
The invention also provides a ceramic heat transfer element, which is obtained by filling pores in the sintered ceramic heat transfer element by adopting the filling method.
The invention also provides an infiltration device for implementing the filling method, which comprises a shell for placing the ceramic heat transfer element, an infiltration agent container and a vacuum pump for vacuumizing the shell; the impregnant container is communicated with the inner cavity of the shell through a communicating pipeline.
The embodiment of the invention provides a method for filling pores of a ceramic heat transfer element, which has the beneficial effects that: the method adopts the adhesive and the heat-conducting filler as the impregnant, immerses the ceramic heat-transfer element in the impregnant under the vacuum condition, adopts the vacuum impregnation method to ensure that the impregnant well enters the through air holes of the ceramic heat-transfer element and then is heated and solidified, and not only can repair the surface defects, but also can repair the internal air hole defects of the ceramic.
It is emphasized that after vacuum infiltration, the average thermal conductivity and the average compressive strength of the ceramic heat transfer element are significantly improved compared to before filling the pores.
The embodiment of the invention also provides a ceramic heat transfer element, which is obtained by filling the pores of the sintered ceramic heat transfer element by adopting the filling method, does not have internal pore defects and surface crack defects, and has high thermal conductivity and compressive strength.
The embodiment of the invention also provides an infiltration device for implementing the filling method, which is characterized in that the ceramic heat transfer element is arranged in the shell, the vacuum degree in the shell is controlled by a vacuum pump, and the infiltration agent in the infiltration agent container is conveyed to the shell by using the communication pipeline to immerse the ceramic heat transfer element. The infiltration device can conveniently carry out vacuum infiltration work of the ceramic heat transfer element, so that air holes in the ceramic can be effectively repaired.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic structural diagram of an infiltration apparatus provided in an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a modified mullite ceramic heat transfer module in an embodiment of the present invention.
Icon: 100-an infiltration device; 1-a ceramic heat transfer element; 2-containing plate; 3-a heater; 4-a shell; 5-compressed gas conveying pipeline; 6-a vacuum pump; 7-impregnant container; 8-a bidirectional pump; 10-a ceramic heat transfer module; 20-a first heat transfer channel; 30-second heat transfer path.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The method for filling pores in a ceramic heat transfer element, the ceramic heat transfer element, and the impregnation apparatus according to the embodiments of the present invention will be described in detail below.
The embodiment of the invention provides a method for filling pores of a ceramic heat transfer element, which adopts a vacuum infiltration method to enable an infiltration agent to infiltrate into straight pores of the ceramic heat transfer element and to repair the pores very well.
The method for filling the pores and the cracks of the mullite ceramic heat transfer element does not need surface glazing and secondary high-temperature sintering, can achieve the purpose of filling the pores and the cracks of the ceramic, can improve the heat conductivity and the overall mechanical strength of the ceramic heat transfer element, is an effective method for filling and repairing the pores and the cracks of the ceramic heat transfer element, and has good application prospect. The method specifically comprises the following steps:
s1, pretreatment
Before the ceramic heat transfer element is treated under vacuum conditions, it is washed and dried to remove impurities and moisture from the surface and pores. Preferably, the drying is performed for 3-5h at 100-120 ℃ to sufficiently remove the moisture in the pores.
This step is a preferable step, and if a ceramic heat transfer element having a clean and dry surface is to be treated, this step may not be performed.
S2, standing in vacuum
The ceramic heat transfer element is kept still for 1-2h under the condition that the vacuum degree is 50-80KPa, and the ceramic heat transfer element is kept still in vacuum before being subjected to vacuum infiltration, so that air in air holes and cracks on the ceramic heat transfer element can be exhausted.
This step is a preferable step, and the effect of pore repair can be further improved by standing in a vacuum state before vacuum infiltration.
S3, vacuum infiltration
The ceramic heat transfer element is immersed in an infiltrant under vacuum conditions for vacuum infiltration, wherein the infiltrant includes a binder and a thermally conductive filler. The inventors have found that the use of a binder and a thermally conductive filler as an infiltrant, in combination with vacuum infiltration, enables the infiltrant to fill very well into the pores inside the ceramic. More importantly, the repairing mode not only can not influence the heat conductivity coefficient of the ceramic, but also can obviously improve the heat conductivity coefficient to a certain extent, and simultaneously can also obviously improve the compressive strength.
It is necessary to supplement that the infiltration agent can be well infiltrated into the pores by vacuum infiltration, which may be due to the capillary action of the straight through pores and cracks of the ceramic heat exchange element, so that the infiltration mixture can infiltrate into the ceramic capillary to completely fill the defects of the straight through pores, cracks, and the like.
Further, the binder is selected from at least one of water glass, organic silicon, phenolic resin and furan resin; preferably, the mass ratio of the binder to the thermally conductive filler is 100: 40-250, preferably 100-150. The inventor finds that the selection of the binder has a remarkable influence on the final treatment effect, the binder adopted in the embodiment of the invention has a better repairing effect on air holes, the heat conductivity coefficient and the compressive strength of the ceramic can be improved to a greater extent, and if other binders except the embodiment of the invention are adopted, the repairing effect cannot be ensured.
Further, the heat-conducting filler is at least one selected from graphite micropowder, silicon carbide micropowder and mullite micropowder, preferably graphite micropowder or silicon carbide micropowder, and the particle size of the heat-conducting filler is 2-10 μm. The graphite micro powder or the silicon carbide micro powder as the heat conducting filler can further improve the heat conductivity coefficient of the ceramic, and the repairing effect is better.
Further, controlling the vacuum degree to be 50-80KPa and the temperature to be 80-120 ℃ in the vacuum infiltration process; preferably, the vacuum degree is controlled to be 60-70KPa in the vacuum infiltration process, the temperature is controlled to be 90-110 ℃, the vacuum infiltration time is 0.5-1h, and the liquid level of the infiltration agent is kept to exceed the height of the ceramic heat transfer element by more than 100mm in the immersion process. The inventors were able to fill the internal pores of the ceramic better by further optimizing the degree of vacuum, temperature and time of infiltration.
S4, compressed air pressure impregnation
In the preferred embodiment of the invention, after vacuum infiltration and before temperature rise and solidification, the pressure of the environment where the ceramic heat transfer element is located is restored to normal pressure, then compressed gas is introduced, and the ceramic heat transfer element is immersed for 0.5 to 1 hour under the condition of the existence of the compressed gas. The infiltration agent can further infiltrate into the internal straight through holes of the ceramic by introducing compressed gas, so that the filling effect of the holes is improved.
Preferably, the pressure of the compressed gas is 0.5 to 0.8MPa, and the pressure of the compressed gas is controlled within the above range, so that the infiltrant can be better infiltrated into the inner pores of the ceramic.
S5, heating and curing
And heating and curing the ceramic heat transfer element filled with the impregnant in the air holes to cure and form the adhesive, wherein the curing temperature is 120-260 ℃, and the curing time is 3-6 h. The curing temperature and time can be set according to the choice of the binder, and are preferably controlled within the above range to ensure better curing and molding of the binder and the filler.
S6, post-processing
After being solidified, the surface of the ceramic heat transfer element is cleaned to ensure that the surface is smooth and free of impurities.
The embodiment of the invention also provides a ceramic heat transfer element, which is obtained by filling pores in the sintered ceramic heat transfer element by adopting the filling method; the ceramic heat transfer element may be a ceramic tube or a ceramic honeycomb heat exchange module. The ceramic heat transfer element has no internal pore defects and surface crack defects, and has high thermal conductivity and compressive strength.
Referring to fig. 1, an infiltration apparatus 100 for implementing the filling method includes a housing 4, an infiltration agent container 7, and a vacuum pump 6 for evacuating the housing; the impregnant container 7 is communicated with the inner cavity of the shell 4 through a communicating pipeline, and a containing plate 2 used for containing the ceramic heat transfer element 1 is arranged in the shell 4. The vacuum degree in the housing 4 is controlled by a vacuum pump 6, and the infiltrant in the infiltrant container 7 is conveyed to the ceramic heat transfer element 1 immersed in the housing 4 by a communication pipe. The infiltration device can conveniently carry out the vacuum infiltration work of the ceramic heat transfer element 1, so that the air holes in the ceramic can be effectively repaired.
In some embodiments, the plurality of holding plates 2 in the housing 4 are arranged from top to bottom to form a holding rack for holding the ceramic heat transfer elements 1, and the plurality of ceramic heat transfer elements 1 can be operated in one vacuum infiltration process to improve the working efficiency.
Specifically, the shell 4 may be a shell structure having a heat insulating effect, so as to better control the temperature during the impregnation process and reduce heat loss.
In some embodiments, a heater 3 for heating the inner cavity of the housing 4 is further disposed in the housing 4 to control the temperature in the housing 4 during the vacuum infiltration process and during the temperature-rising curing process. Specifically, the heater 3 may be in the form of a heating pipe, and the specific structure thereof is not limited.
In some embodiments, the infiltration apparatus 100 further comprises a compressed air delivery pipe 5, wherein a discharge end of the compressed air delivery pipe 5 is communicated with the inner cavity of the housing 4, and an inlet end of the compressed air delivery pipe 5 can be connected with an air storage tank for delivering compressed air, such as compressed air.
In some embodiments, a bi-directional pump 8 is provided on the communication line between infiltrant holder 7 and housing 4 to evacuate the infiltrant after infiltration is complete for elevated temperature curing operations.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
Referring to fig. 2, the ceramic heat transfer module 10 to be processed is a modified mullite ceramic heat transfer element, a first heat transfer channel 20 and a second heat transfer channel 30 are arranged on the modified mullite ceramic heat transfer element in a crossed manner, and after the ceramic module is sintered and molded, a large number of holes, through air holes and microcracks exist in the heat exchange module, so that the first heat transfer channel 20 and the second heat transfer channel 30 on the ceramic heat transfer module 10 are mixed in series, and air hole filling treatment is required.
The embodiment provides a method for filling pores of a ceramic heat transfer element, which adopts the device in fig. 1 and comprises the following steps:
(1) pretreatment: and (3) cleaning the ceramic heat transfer module 10 by using normal-temperature water of 0.5MPa to remove impurities on the surface and in the air holes, and then drying the ceramic heat transfer module in a drying oven at about 110 ℃ for 3 hours to completely remove residual water in the air holes.
(2) Standing in vacuum: the dried ceramic heat transfer modules 10 are sequentially placed on the holding plate 2 of the infiltration device 100, and a certain gap should be ensured between each ceramic module. The vacuum pump 6 of the impregnation apparatus 100 was turned on to maintain a vacuum of 6x104Pa, and keeping for 1h to ensure that air in the air holes of the ceramic module is exhausted.
(3) Vacuum infiltration: selecting 3-micron silicon carbide micro powder as a filler, and water glass as a binder to prepare an impregnant, wherein the mass ratio of the binder to the heat-conducting filler is 100: 25; the prepared impregnant was introduced into the impregnation apparatus 100, and the temperature in the impregnation apparatus 100 was raised from room temperature to 100 ℃ and maintained for 1 hour.
(4) Compressed air pressure infiltration: and (3) closing the vacuum pump, and introducing 0.5MPa of air into the infiltration device for 0.5h to ensure that the infiltration agent is fully pressed into the pores and cracks filled with the ceramic.
(5) Heating and curing: reducing the pressure of the infiltration device to normal pressure, pumping out the residual infiltration agent, and starting to heat and solidify the ceramic heat transfer element after infiltration treatment, wherein the solidification temperature is 130 ℃, and the temperature is kept for 4 h.
(6) And (3) post-treatment: and after the temperature is reduced to the normal temperature, taking out the ceramic heat exchange module, and removing impurities on the surface of the heat transfer flow channel, namely completing the air hole filling treatment of the heat transfer module to obtain the qualified ceramic heat transfer module.
Example 2
This example provides a method for filling pores in a ceramic heat transfer element, which uses the apparatus shown in fig. 1, and is different from example 1 only in that:
(1) pretreatment: and (3) cleaning the ceramic heat transfer module 10 by using normal-temperature water of 0.5MPa to remove impurities on the surface and in the air holes, and then drying the ceramic heat transfer module in a drying oven at about 100 ℃ for 5 hours to completely remove residual water in the air holes.
(2) Standing in vacuum: the dried ceramic heat transfer modules 10 are sequentially placed on the holding plate 2 of the infiltration device 100, and a certain gap should be ensured between each ceramic module. The vacuum pump 6 of the impregnation apparatus 100 was started to maintain the vacuum at 5x104Pa, and keeping for 1h to ensure that air in the air holes of the ceramic module is exhausted.
(3) Vacuum infiltration: selecting 2-micron graphite micro powder as a filler, and furan resin as a binder to prepare an impregnant, wherein the mass ratio of the binder to the heat-conducting filler is 100: 40; the prepared impregnant is introduced into the impregnation device 100, and the temperature in the impregnation device 100 is raised from the normal temperature to 80 ℃ and kept for 0.5 h.
(4) Compressed air pressure infiltration: and (3) closing the vacuum pump, and introducing 0.5MPa of air into the infiltration device for 1h to ensure that the infiltration agent is fully pressed into the pores and cracks filled with the ceramic.
(5) Heating and curing: reducing the pressure of the infiltration device to normal pressure, pumping out the residual infiltration agent, and starting to heat and solidify the ceramic heat transfer element subjected to infiltration treatment, wherein the solidification temperature is 120 ℃, and the temperature is kept for 6 hours.
(6) And (3) post-treatment: and after the temperature is reduced to the normal temperature, taking out the ceramic heat exchange module, and removing impurities on the surface of the heat transfer flow channel, namely completing the air hole filling treatment of the heat transfer module to obtain the qualified ceramic heat transfer module.
Example 3
This example provides a method for filling pores in a ceramic heat transfer element, which uses the apparatus shown in fig. 1, and is different from example 1 only in that:
(1) pretreatment: and (3) cleaning the ceramic heat transfer module 10 by using normal-temperature water of 0.5MPa to remove impurities on the surface and in the air holes, and then drying the ceramic heat transfer module in a drying box at about 120 ℃ for 3 hours to completely remove residual water in the air holes.
(2) Standing in vacuum: the dried ceramic heat transfer modules 10 are sequentially placed on the holding plate 2 of the infiltration device 100, and a certain gap should be ensured between each ceramic module. The vacuum pump 6 of the impregnation apparatus 100 was started to maintain the vacuum at 8x104Pa, and keeping for 2h to ensure that air in the air holes of the ceramic module is exhausted.
(3) Vacuum infiltration: selecting 10-micron mullite micropowder as a filler, using phenolic resin as a binder to prepare an impregnant, wherein the mass ratio of the binder to the heat-conducting filler is 100: 100; the prepared impregnant is introduced into the impregnation device 100, and the temperature in the impregnation device 100 is raised from the normal temperature to 120 ℃ and kept for 1 hour.
(4) Compressed air pressure infiltration: and (3) closing the vacuum pump, and introducing 0.8MPa of air into the infiltration device for 0.5h to ensure that the infiltration agent is fully pressed into the pores and cracks filled with the ceramic.
(5) Heating and curing: reducing the pressure of the infiltration device to normal pressure, pumping out the residual infiltration agent, and starting to perform heating and curing treatment on the ceramic heat transfer element after infiltration treatment, wherein the curing temperature is 260 ℃, and preserving heat for 3 hours.
(6) And (3) post-treatment: and after the temperature is reduced to the normal temperature, taking out the ceramic heat exchange module, and removing impurities on the surface of the heat transfer flow channel, namely completing the air hole filling treatment of the heat transfer module to obtain the qualified ceramic heat transfer module.
Comparative example 1
This comparative example provides a method for filling pores in a ceramic heat transfer element using the apparatus of FIG. 1, differing from example 1 only in that: the adhesive replaces the water glass with polyvinyl alcohol, the proportion of the adhesive and the filling material is unchanged, and the thermal conductivity and the compressive strength of the ceramic heat transfer module are hardly improved after infiltration because the viscosity of the polyvinyl alcohol is low and volatile components exist.
Comparative example 2
This comparative example provides a method for filling pores in a ceramic heat transfer element using the apparatus of FIG. 1, differing from example 1 only in that: the binder replaces the water glass with methyl cellulose, the proportion of the binder and the filler is unchanged, and the heat conductivity and the compressive strength of the ceramic heat transfer module are hardly effectively improved after infiltration.
Test example 1
The ceramic heat transfer members after filling in examples 1 to 3 and comparative example 1 were tested for compressive strength and average thermal conductivity by a conventional method, and the results were as follows:
the average normal temperature compressive strength of the ceramic heat transfer element not filled was 58MPa, the average normal temperature compressive strength of the ceramic heat transfer element after filling in example 1 was 65MPa, and the average normal temperature compressive strength corresponding to examples 2 to 3 and comparative example 1 was 66 MPa.
The average thermal conductivity of the ceramic heat transfer member not to be filled was 7.5W/(m · K), the average thermal conductivity of the ceramic heat transfer member after filling in example 1 was 9.5W/(m · K), and the average thermal conductivity corresponding to examples 2 to 3 and comparative example 1 was 9.6W/(m · K).
Test example 2
Example 1 the morphology of the interior and surface of the ceramic before and after filling was tested. Before vacuum infiltration, the ceramic heat transfer element has macroscopic crack defects on the outer surface and visible air hole defects inside, and the pressure resistance is less than or equal to 0.2 MPa. After vacuum infiltration, the outer surface is smooth, the inner texture is compact, and the pressure resistance is more than or equal to 1.0 MPa.
In summary, the method for filling pores of a ceramic heat transfer element provided by the invention adopts the adhesive and the heat conductive filler as the impregnant, the ceramic heat transfer element is immersed in the impregnant under the vacuum condition, and the impregnant well enters the through pores of the ceramic heat transfer element by adopting the vacuum impregnation method and then is heated and cured, so that the surface defects and the internal pore defects of the ceramic can be repaired. After vacuum infiltration, the average thermal conductivity and average compressive strength of the ceramic heat transfer element are significantly improved compared to before pore filling.
The embodiment of the invention also provides a ceramic heat transfer element, which is obtained by filling the pores of the sintered ceramic heat transfer element by adopting the filling method, does not have internal pore defects and surface crack defects, and has high thermal conductivity and compressive strength.
The embodiment of the invention also provides an infiltration device for implementing the filling method, which is characterized in that the ceramic heat transfer element is arranged on the containing plate in the shell, the vacuum degree in the shell is controlled by a vacuum pump, and the infiltration agent in the infiltration agent containing device is conveyed to the shell by using the communication pipeline to immerse the ceramic heat transfer element. The infiltration device can conveniently carry out vacuum infiltration work of the ceramic heat transfer element, so that air holes in the ceramic can be effectively repaired.
The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Claims (10)
1. A method of filling pores in a ceramic heat transfer element, comprising: carrying out vacuum infiltration on the ceramic heat transfer element in an infiltration agent under the vacuum condition, and then heating and curing the ceramic heat transfer element with the air holes filled with the infiltration agent;
wherein the infiltrant includes a binder and a thermally conductive filler.
2. The method of filling pores of a ceramic heat transfer element according to claim 1, wherein the binder is at least one selected from the group consisting of water glass, silicone, phenol resin, and furan resin;
preferably, the mass ratio of the binder to the thermally conductive filler is 100: 10-100, preferably 100: 40.
3. The method for filling pores of a ceramic heat transfer element according to claim 1 or 2, wherein the heat conductive filler is at least one selected from graphite fine powder, silicon carbide fine powder and mullite fine powder, preferably graphite fine powder or silicon carbide fine powder;
preferably, the particle size of the thermally conductive filler is 2 to 10 μm.
4. The method for filling the pores of the ceramic heat transfer element according to claim 1, wherein the vacuum degree is controlled to be 50-80KPa and the temperature is controlled to be 80-120 ℃ in the vacuum infiltration process;
preferably, the vacuum degree is controlled to be 60-70KPa and the temperature is controlled to be 90-110 ℃ in the vacuum infiltration process;
preferably, the time for vacuum infiltration is 0.5 to 1 hour.
5. The method for filling pores in a ceramic heat transfer element according to claim 4, wherein the ceramic heat transfer element is allowed to stand for 1 to 2 hours under a vacuum degree of 50 to 80KPa before the ceramic heat transfer element is vacuum-infiltrated;
preferably, the level of infiltrant is maintained above the height of the ceramic heat transfer element by more than 100mm during immersion.
6. The method for filling the pores of the ceramic heat transfer element according to claim 4, wherein before the temperature rise and solidification are carried out after the vacuum infiltration, the pressure of the environment where the ceramic heat transfer element is located is restored to normal pressure, then compressed gas is introduced, and the ceramic heat transfer element is immersed for 0.5 to 1 hour in the presence of the compressed gas;
preferably, the pressure of the compressed gas is 0.5 to 0.8 MPa.
7. The method for filling the pores of the ceramic heat transfer element as claimed in claim 1, wherein the curing temperature in the temperature-raising curing process is 120-260 ℃, and the curing time is 3-6 h;
preferably, after being cured, the surface of the ceramic heat transfer element is cleaned.
8. The method of filling pores of a ceramic heat transfer element according to claim 1, wherein before the ceramic heat transfer element is treated under vacuum conditions, cleaning and drying are performed to remove impurities and moisture in the surface and pores;
preferably, the drying is performed at 100-120 ℃ for 3-5 h.
9. A ceramic heat transfer element obtained by pore-filling a sintered ceramic heat transfer element by the filling method according to any one of claims 1 to 8;
preferably, the ceramic heat transfer element is a ceramic tube or a ceramic honeycomb heat exchange module.
10. An infiltration apparatus for carrying out the filling method according to any one of claims 1 to 8, comprising a case for placing a ceramic heat transfer element, an infiltrant holder, and a vacuum pump for evacuating the inside of the case; the impregnant container is communicated with the inner cavity of the shell through a communication pipeline;
preferably, a containing plate for containing the ceramic heat transfer element is arranged in the shell;
preferably, a heater for heating the inner cavity of the shell is further arranged in the shell;
preferably, the device further comprises a compressed air conveying pipeline, and the discharge end of the compressed air conveying pipeline is communicated with the inner cavity of the shell;
preferably, a bidirectional pump is arranged on the communication pipeline between the impregnant container and the shell;
preferably, the containing plates in the shell are arranged from top to bottom to form a containing rack for containing the ceramic heat transfer elements.
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