KR20120086247A - Seamless Cylindrical Metal Fiber Mat and Method of The Same - Google Patents

Abstract

PURPOSE: A seamless cylindrical metal fiber mat and a method for manufacturing thereof are provided to be manufactured for various diameter and height by forming a metal fiber mat to fit the outer diameter of a cylindrical burner. CONSTITUTION: A seamless cylindrical metal fiber mat is installed in the exterior(12) of the distributor plate of a surface combustion burner. A seamless cylindrical metal fiber mat(130) is formed into one body and inserted in the external portion of the distributor plate. The seamless cylindrical metal fiber mat is formed into a knitted mat. The seamless cylindrical metal fiber mat is composed of 18 to 27 wt.% of chrome, 3 to 7 wt.% of aluminum, 0.05 to 0.5 wt.% of zirconium and yttrium, and residual iron.

Description

Seamless Cylindrical Metal Fiber Mat and Method of The Same

FIELD OF THE INVENTION The present invention relates to the manufacture of metal fiber mats for use in cylindrical surface combustion burners, and more particularly, to a seamless cylindrical metal fiber mat such as welds and a method of manufacturing the same.

In general, a cylindrical burner is a burner applied to a heat exchanger of a circular type, as shown in FIGS. 1 and 2, an inner distribution plate 11 and an outer distribution unit provided outside the inner distribution plate 11. A plate (External distributor), a metal fiber mat 13 attached to the outer circumferential surface of the outer distribution plate 12, and coupled to both ends of the inner distribution plate 11 and the outer distribution plate 12, respectively Consisting of a flange 14 and an end cap 15.

In this case, conventionally, the metal fiber mat 13 has been a problem by joining the outer distribution plate 12 by welding. Specifically, as shown in FIG. 3, the metal fiber mat 13 is cut to a length corresponding to the height of the cylindrical burner 10 and the circumference of the outer distribution plate 12, and the metal fiber mat ( 13 is welded (W) to one end of the outer distribution plate 12, and the other end is pulled up tightly so that the metal fiber mat 13 is in close contact with the outer distribution plate 12, and then the initial welding portion ( The attachment was made by welding to W).

However, as described above, when the metal fiber mat 13 is attached by welding, pores of the welded portions W and W 'are blocked, and thus the premixed gas does not pass, there is a problem in that no flame is generated. In addition, when the metal fiber mat 13 is attached, welding is carried out as closely as possible in consideration of the resulting orientation so that the premixed gas does not leak. W ') is located inside the flame surface of the burner, causing repeated problems such as cracking and tearing of adjacent parts due to repeated heating and cooling during prolonged use.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a seamless cylindrical metal fiber mat and a method of manufacturing the same, which can improve the durability and workability by removing the weld.

As a means for solving the above technical problem,

The present invention provides a seamless cylindrical metal fiber mat, wherein the metal fiber mat provided on the outside of the distribution plate of the surface combustion burner is integrally formed in a cylindrical shape and mounted on the outside of the distribution plate in an inserting manner.

In this case, the seamless cylindrical metal fiber mat is preferably a knitted mat.

In this case, it is preferable that the material of the seamless cylindrical metal fiber mat is iron-chromium alloy or stainless steel.

In this case, the iron-chromium alloy may include chromium (Cr): 18 to 27% by weight, aluminum (Al): 3 to 7% by weight, balance iron, and 0.05 to 0.5% by weight of zirconium (Zr) and It is also possible to further contain yttrium (Y).

In addition, the present invention, (a) forming a plurality of irregularities in the longitudinal direction on the metal fiber bundle, (b) knitting the metal fiber bundle into a double tissue, (c) step (b) It provides a method for producing a seamless cylindrical metal fiber mat comprising the annealing treatment of the knitted fabric obtained in (d), (d) flattening the knitted fabric and (e) forming the knitted fabric into a cylindrical shape.

According to the present invention, by removing the weld of the metal fiber mat, it is possible to minimize the loss of the heating surface, to ensure durability, and as a result, to improve the quality.

In addition, since the cylindrical metal fiber mat only needs to be covered on the external distribution plate, the assembly performance is improved, as well as the production time is shortened, and the production cost can be reduced and the automation is also possible.

In addition, since the metal fiber mat is manufactured to the outer diameter of the cylindrical burner, it can be easily applied to the burner having no material loss and having various diameters and heights.

1 is an exploded perspective view of a cylindrical burner,
2 is an assembly view of the cylindrical burner,
3 is a view showing a metal fiber mat and a method of attaching the same according to the prior art;
4 is a view showing a seamless cylindrical metal fiber mat and a method of attaching the same according to a preferred embodiment of the present invention;
5 shows the combustion principle of a surface combustion burner;
6 is a view illustrating a process of forming a loop when knitting a seamless cylindrical metal fiber mat according to a preferred embodiment of the present invention;
7 is a diagram illustrating a method of manufacturing a seamless cylindrical metal fiber mat according to a preferred embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

4 illustrates a seamless cylindrical metal fiber mat and a method of attaching the same according to a preferred embodiment of the present invention.

As shown in FIG. 4, the seamless cylindrical metal fiber mat 130 according to the preferred embodiment of the present invention is formed in an integral cylindrical shape and mounted to the outside of the outer distribution plate 12. That is, in the present invention, instead of attaching the metal fiber mat to the distribution plate by welding, a method of manufacturing a cylindrical shape according to the diameter and length of the outer distribution plate 12 and covering the outside of the outer distribution plate 12 is performed. The technical characteristics of the present invention include improved durability, ease of assembly, and combustion efficiency.

In this case, as the material of the seamless cylindrical metal fiber mat 130, an iron-chromium alloy having excellent heat resistance is used. Specifically, 18 to 27% by weight of chromium (Cr) and 3 to 7% by weight, preferably It may include 5 to 7% by weight of aluminum (Al) and the balance iron. In addition, zirconium (Zr), yttrium (Y) and the like may be added to the iron-chromium alloy by adding 0.05 to 0.5% by weight, preferably 0.1 to 0.3% by weight. In addition, it is also possible to use stainless steel, in which case it is preferable to use stainless steel 316L.

On the other hand, the seamless cylindrical metal fiber mat 130 is produced by making a bundle of metal fiber to the weight of 0.5 ~ 1.5 g / m of metal fiber of wire diameter 22 ~ 40㎛, so prepared metal fiber mat 1,000 ~ 2500 g It will have a weight of / m 2. In this case, when weaving the bundle of metal fibers at 1.5g / m or more, the thickness of the bundle of metal fibers becomes thick, and when the diameter of the cylindrical metal fiber mat is small, the arrangement of the knitting needles becomes too narrow, so that weaving is difficult, and the knitting needles during weaving are small. If a problem occurs, the metal fiber bundle is less than 0.5g / m, the tensile strength of the metal fiber bundle is weakened and broken when knitting, causing a failure.

In addition, the thickness of the seamless cylindrical metal fiber mat 130 is preferably 1.5 ~ 3.5mm. This is because if the thickness is too thin or too thick as a surface combustion media, it is difficult to produce a stable combustion shape, and it is difficult to apply it as a combustion media of a burner having a performance of TDR (Turn Down Ratio) 10: 1.

In the present invention, the seamless cylindrical metal fiber mat 130 is knitted by a knitting machine. The knitting machine is a kind of circular knitting machine, the needles are arranged in the circumferential direction to knit the metal fiber mat according to a predetermined pattern. In this case, the seamless cylindrical metal fiber mat 130 may have a diameter ranging from Ø50 to Ø300 depending on the application purpose of the cylindrical burner. However, the diameter of these metal fiber mats is usually the most widely used, and it is of course also possible to knit Ø300 or more as necessary.

In this regard, hereinafter, the difference between the woven mat and the knitting mat will be described in detail with reference to the manufacturing method of the present invention employing the knitting mat.

Difference between weave mat and knitting mat

Array geometry

First, weaving mats are woven as wefts and warp yarns cross at right angles, while knitting mats are loopable and form tissues, which are good stretchy and flexible, and have good properties as metal fiber mats for combustion media due to their high air permeability. have.

thickness

In general, weaving mats that can be applied as metal fiber media for combustion are about 1.2 to 1.7 mm thick, and knitting mats can change the organizational structure to a thickness of 1.5 to 3.5 mm. When forming, since the three-dimensional tissue arrangement in the thickness direction can be formed thicker than the woven mat.

5 shows the combustion principle of a surface combustion burner.

As shown in FIG. 5, combustion in the surface combustion burner occurs at the surface of the mat, which is divided into a combustion zone and a cooling zone. Specifically, the combustion region is a portion where actual combustion occurs and becomes a high temperature of 1,000 ° C., and the cooling region cools the upper portion that becomes high temperature by combustion without the actual combustion as the premixed gas passes through. As such, in the case of the surface combustion burner, since a cooling zone is formed at the bottom of the mat, heat transfer does not occur inside the burner, so that it is maintained below the spontaneous ignition temperature of the premixed gas. As a result, the durability of the mat and the protection of parts can be obtained. . Therefore, when the air permeability is also the same, the thicker the mat, the wider the cooling area is secured and durability can be improved.

However, in the case of the woven mat, there is a method of weaving by increasing the thickness of the metal fiber in order to increase the thickness of the mat, but if the thickness of the metal fiber is increased in this way, the density of the metal fiber per unit area becomes too high, so the air permeability is reduced and the thickness of the mat It is not possible to increase it by more than 2mm. Knitting mats, on the other hand, have the same metal fiber density per unit area because the loop forming method is organized three-dimensionally in space rather than on a plane like a woven mat, but the volume per unit area increases, so that air permeability is similar to that of the woven mat. There is an advantage to increase the thickness while maintaining.

This property allows for the durability of the metal fiber mat, which is responsible for the combustion section in terms of combustion media, for example, a wide TDR characteristic, etc. For this reason, there are more knitted metal fiber mats in combustion equipment such as high efficiency condensing boilers. Is being applied.

Combustion performance

The performance index indicating burner performance is the TDR (Turn Down Ratio). The TDR represents the ratio of the highest output and the lowest output that can be realized in the burner. The larger the TDR, the more calorie control is possible in one burner, so that it can be applied to a high efficiency combustion system.

In surface-burning burners, metal fiber mats act as flame holders, providing a wider combustion area for knitted fabrics that form loops and have three-dimensional tissue structures. Specifically, in the case of high load combustion, the flow rate of the premixed gas increases with increasing flow rate. As the flow rate increases, the flame rises on the surface of the mat.In the case of the knitted mat, the thickness of the knit mat is thick and the loop structure has a three-dimensional shape. Can be. On the other hand, in the case of low load combustion, combustion is formed in the mat, and since the combustion region is wider than the woven mat, abnormal combustion such as rust salt does not occur, and combustion is possible in a region of a lower output range.

Heat deformation

Since the surface of the metal fiber mat of the surface combustion burner becomes a high temperature of 1,000 ° C. or more, the metal fibers constituting the metal fiber mat also increase during combustion. In the case of the woven mat, since the metal fibers are in a planar arrangement and there is no elasticity, when they are stretched by heat, they are separated from the distribution plate (perforated plate) attached to the mat, and the cooling area is not formed normally. Backfire occurs.

However, in the case of knitted mats, metal fibers have a three-dimensional array, and the mats themselves have good elasticity, and they are pulled and attached to maintain a certain tensile force when attached to a distribution plate. Therefore, even if the metal fiber increases due to the heat deformation has the advantage that it is not spaced apart from the distribution plate. In addition, since the cooling region is relatively large, since the metal fibers corresponding to the cooling region of the mat hold the upper region where combustion proceeds without stretching, the phenomenon of easy separation does not occur.

As described above, the knitting mat has superior durability and thermal properties compared to the woven mat, and in view of the above characteristics, the present invention adopts a knitting mat. Hereinafter, a method of manufacturing a seamless cylindrical metal fiber mat according to the present invention will be described. It demonstrates concretely.

Manufacturing method

Pretreatment

First, the metal fiber bundle may be used by forming irregularities at intervals of 0.3 mm to 50 mm in the longitudinal direction to prevent the individual metal fibers from falling out and improve the entanglement. When the bundle of metal fibers is stretched in the longitudinal direction during the weaving or knitting process, it is desirable to form the unevenness before weaving the fabric to improve the entanglement because the metal fiber strands may fall out if the entanglement is not good.

Unlike ordinary fibers, metal fibers have a low elongation, and thus are subjected to a tensile force in the longitudinal direction during the weaving of the fabric. When excessive tensile force is applied, the metal fiber bundle is broken or the knitting needle is broken. Therefore, in the present invention, by forming irregularities in the metal fiber bundle at regular intervals, artificial elongation is added to prevent the metal fiber bundle or the knitting needle from being broken.

Knitting

Knitting in the present invention is to apply a circular knitting machine to knit a cylindrical knitted fabric having no weld seam of the specified dimensions. Since the bundle of metal fibers is thick, it is impossible to knit with a normal fiber knitting machine, and it is impossible to knit the tissue tightly so that normal combustion can be achieved. In addition, there should be no separation from the distribution plate due to heat deformation in the properties that the knitting mat for the surface combustion burner should have.

Therefore, in the present invention, it is possible to knit with a thick metal fiber bundle, and configured to have a double-structured knit fabric structure in order to increase resistance to heat deformation. In other words, the metal fiber knitted fabric has a double structure so that the two-stage fabric included in the cooling zone can catch the one-stage portion that is heated to a high temperature, thereby improving heat resistance, and the premixed gas passes through. The longer the path is, the more extensive the combustion is possible.

6 is a view showing a process of forming a loop when knitting a seamless cylindrical metal fiber mat according to a preferred embodiment of the present invention.

Specifically, as shown in (a) of FIG. 6, the first end has a loop formed at the lower nose of the first needle and the upper nose of the second needle, and as shown in FIG. Loops are formed and knit in the lower nose of needle 1 and the lower nose of needle 2.

The metal fiber mat knitted in this way has a distinction between the front and the back. Usually, the first end is a flame part in which a flame is formed, and the second end belongs to a cooling zone, and thus the high temperature is formed because the thermal strain is hardly generated. It serves to hold the thermal deformation of the end, and to form a turbulent flow in the flow of the premixed gas to ensure the combustion time so that the premixed gas is completely burned on the mat surface.

After treatment

In the knitting process as described above, the residual stress due to the tensile stress (Stress) is left in the metal fiber, this residual stress degrades the mechanical properties such as tensile strength to reduce the durability of the metal fiber mat. Therefore, in the present invention, the annealing treatment after knitting to remove the residual stress to restore the mechanical properties.

In this case, the annealing process is to heat the mat to 500 ~ 600 ℃ and then slowly cooled to remove the residual stress. Heat during annealing is heated by indirect heating because the discoloration occurs when the flame touches the product. In the present invention, as shown in Figure 7 while maintaining the inside of the heating chamber 110 at the annealing temperature constant while the metal fiber mat 130 passes between the mesh conveyor 120 inside the heating chamber 110, residual stress Due to this, the dried portion is flattened, and the thickness and the surface of the metal fiber mat 130 are kept constant through a leveling process 140 during the cooling after the heating. In this case, the rolling process is usually made within 0.2 ~ 1mm, and when the rolling is completed is wound around the roll using a rewinder 150 or cut to a suitable length to produce a cylindrical according to the length and diameter of the cylindrical burner.

Preferred embodiments of the present invention have been described in detail above with reference to the drawings. The description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention.

Therefore, the scope of the present invention is represented by the following claims rather than the detailed description, and all changes or modifications derived from the meaning, scope, and equivalent concepts of the claims are included in the scope of the present invention. Should be interpreted as

10: cylindrical burner 11: internal distribution plate
12: outer distribution plate 13: metal fiber mat
14 flange 15 end cap
110: heating chamber 120: mesh conveyor
130: Seamless Cylindrical Metal Fiber Mat
140: Leveling 150: Rewinder

Claims (6)

In the metal fiber mat installed outside the distribution plate of the surface combustion burner,
Seamless cylindrical metal fiber mat, characterized in that made of an integral cylindrical shape mounted on the outside of the distribution plate. The method of claim 1,
The seamless cylindrical metal fiber mat is a seamless cylindrical metal fiber mat, characterized in that the knitting mat. The method according to claim 1 or 2,
The seamless cylindrical metal fiber mat is a seamless cylindrical metal fiber mat, characterized in that the iron-chromium alloy or stainless steel. The method of claim 3, wherein
The iron-chromium alloy is chromium (Cr): 18 to 27% by weight, aluminum (Al): 3 to 7% by weight, seamless cylindrical metal fiber mat, characterized in that the balance iron. The method of claim 4, wherein
The iron-chromium alloy is a seamless cylindrical metal fiber mat, characterized in that it further comprises 0.05 to 0.5% by weight of zirconium (Zr) and yttrium (Y). A method of manufacturing a metal fiber mat consisting of an integral cylinder,
(a) forming a plurality of irregularities in the longitudinal direction on the bundle of metal fibers;
(b) knitting the bundle of metal fibers into a double tissue;
(c) annealing the knitted fabric obtained in step (b);
(d) flattening the knit fabric; And
(e) forming the knitted fabric into a cylindrical shape;
Seamless cylindrical metal fiber mat manufacturing method comprising a.

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