Method for manufacturing ceramic filter

Abstract

A method of manufacturing a ceramic filter for hot gas filtration, and, more particularly, to a method of manufacturing a ceramic filter for hot gas filtration through a drying process. The ceramic filter manufactured by the method is advantageous in that the pore size thereof can be easily adjusted, and the filtering area thereof can be maximized, thus improving the performance thereof. Consequently, the method of manufacturing a ceramic filter can be usefully used in the filter-related industry because a high-performance ceramic filter can be manufactured at a low cost and at low energy.

Claims

1. A method of manufacturing a porous ceramic filter, comprising: filtering a carrier gas including a ceramic-forming composition in the form of a powder on a surface of a polymer filter body having pores of a first size, the ceramic-forming composition containing ceramic precursor particles of a second size and inorganic and/or organic binder, to form a ceramic-forming composition layer on the surface of the polymer filter body (step 1); and sintering the resultant in step 1, to form a ceramic filter having a pore size of a third size formed by sintering the ceramic precursor particles of the second size, while burning out the polymer filter body (step 2) wherein the second size is bigger than the first size.

2. The method according to claim 1, wherein step 1 is repeated at least 2 times using the ceramic precursor particles of the same size.

3. The method according to claim 1, wherein step 1 is repeated at least 2 times varying the size of ceramic precursor particles and/or the material of ceramic precursor particles.

4. The method according to claim 1, wherein the ceramic precursor particles are silicon carbide (SiC).

5. The method according to claim 1, wherein the inorganic and/or organic binder is mullite (3Al.sub.2O.sub.3.SiO.sub.2), zirconia (ZrO.sub.2), calcium carbonate (CaCO.sub.3), carboxymethyl cellulose, or a combination thereof.

6. The method according to claim 1, wherein the ceramic-forming composition comprises silicon carbide (SiC), mullite (3Al.sub.2O.sub.3.SiO.sub.2), zirconia (ZrO.sub.2), calcium carbonate (CaCO.sub.3), and carboxymethyl cellulose.

7. The method according to claim 6, wherein the ceramic-forming composition comprises silicon carbide, mullite, zirconia, calcium carbonate, carboxymethyl cellulose, and water at a weight ratio of 70˜75:3˜4:3˜4:0.5˜1.0:1˜2:10˜20.

8. The method according to claim 1, wherein the ceramic-forming composition further comprises water.

9. The method according to claim 1, wherein the size of ceramic precursor particles of the second size ranges from 5 μm to 100 μm.

10. The method according to claim 1, wherein the polymer filter body is made of polyester, polypropylene, acryl, polyamide, or polyimide.

11. The method according to claim 1, wherein the filtering step is performed at a rate of from 0.5 m/min to 10 m/min.

12. The method according to claim 1, wherein ceramic-forming composition layer has a thickness of from 1 mm to 10 mm.

13. The method according to claim 1, wherein the sintering is performed at a temperature of from 1400° C. to 1500° C.

14. The method according to claim 1, wherein a heating rate in step 2 of sintering ranges from 3° C./min to 4° C./min.

15. The method according to claim 1, wherein the sintering is performed for from 1 hour to 5 hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view showing a process of manufacturing a ceramic filter according to the present invention.

(2) FIG. 2 shows the figure (A) of a polymer filter body used in manufacturing a ceramic filter, the figure (B) of the manufactured ceramic filter, and the morphology (C) of surface of the ceramic filter observed by a scanning electron microscope.

(3) FIG. 3 is a graph showing the filtration efficiency of the ceramic filter according to the present invention.

DETAILED DESCRIPTION

(4) Hereinafter, the present invention will be described in more detail with reference to the following Examples. However, these Examples are set forth to illustrate the present invention, and the scope of the present invention is not limited thereto.

Examples 1 to 3: Manufacturing Ceramic Filter

(5) FIG. 1 schematically shows a process of manufacturing a ceramic filter.

(6) Specifically, in order to manufacture ceramic filters for hot gas filtration, first, a ceramic composition powder containing silicon carbide, mullite, zirconia, calcium carbonate, carboxymethyl cellulose, and water at a weight ratio of 73.8:3.7:3.7:0.8:1.6:16.4 was injected to pass through a polymer filter body (average pore size: 3 μm, polyester, manufactured by Daesung Filter Tech. Co., Ltd.) together with air through a powder inlet. In this case, silicon carbide having a particle size of 10 μm (Example 1), silicon carbide having a particle size of 25 μm (Example 2), and silicon carbide having a particle size of 50 μm (Example 3) were respectively used. Further, the filtration of the ceramic composition powder was conducted at the rate of 5 m/min, and the thickness of a ceramic composition powder layer was adjusted to 5 mm.

(7) Thereafter, the polymer filter body provided with the ceramic powder layer was sintered at 1450° C. for 2 hours, so as to manufacture a ceramic filter. During the sintering, a heating rate of 3.3° C./min was maintained from room temperature to sintering temperature.

Experimental Example 1: Examination of Structural Characteristics of Ceramic Filter

(8) In order to examine the structural characteristics of the ceramic filter manufactured in Example 2, the surface of the ceramic filter of the present invention was observed with a scanning electron microscope (SEM).

(9) The results thereof are shown in FIG. 2.

(10) In FIG. 2, (A) shows the figure of a polymer filter body used in manufacturing the ceramic filter of the present invention, (B) shows the figure of the manufactured ceramic filter, and (C) shows the results of observing the surface of the ceramic filter with a scanning electron microscope.

(11) From FIG. 2, it was found that a uniform and compact ceramic layer was formed by the manufacturing method of the present invention.

Experimental Example 2: Evaluation of Performances of Ceramic Filter

(12) In order to evaluate the performances of the ceramic filter of the present invention, the filtration efficiency (collection efficiency) of each of the ceramic filters manufactured in Examples 1 to 3 was measured.

(13) In order to measure the filtration efficiency of each of the manufactured ceramic filters, each of the manufactured ceramic filters was mounted on a filter bag testing device, and fly ashes were generated as test particles. The speed of a fluid passing through the filter bag was fixed at 1 m/min, and then the number concentration of dust at the front and rear ends of the ceramic filter was measured by an aerodynamic particle sizer (Model: 3321, TSI Instruments), so as to measure the filtration efficiency thereof.

(14) The results thereof are shown in FIG. 3.

(15) From FIG. 3, it was found that the ceramic filter manufactured using silicon carbide having a particle size of 10 μm to 50 μm could filter fine contaminants with a size of 1 μm or less at a rate of 90% or more.