Insulation panel, method of manufacturing and use thereof

Abstract

The insulation panel (100) comprises an envelope (20) within with a core (10) of compressed microporous insulation material is provided. The envelope (100) comprises a first and a second facer (21, 22), which are united at a side into a flange (30). The flange (30) is provided with a first edge (31) and a second edge (32). The first edge (31) constitutes a removable closure, which can be removed at a later stage to enable elongation of the core (10) of compressed microporous insulation material and therewith bending of the insulation panel (100) to be arranged at a curved surface of an object.

Description

[0001] Insulation panel, method of manufacturing and use thereof

[0002] FIELD OF THE INVENTION

[0003] The invention relates to an insulation panel comprising an envelope and a core of compressed microporous insulation material within said envelope, which insulation panel extends in a first main direction and a second main direction and has a thickness wherein said envelope comprising a first facer and a second facer that are mutually attached on opposed sides of the insulation panel in said first main direction and in said second main direction, which microporous insulation material comprises an inorganic insulation powder, an opacifier and a fiber.

[0004] The invention further relates to a method of manufacturing such an insulation panel, and to the use thereof.

[0005] BACKGROUND OF THE INVENTION

[0006] Insulation panels of such microporous insulation material have been known and produced industrially for almost 50 years. The term 'microporous' is used herein to identify porous or cellular materials in which the ultimate size of the cells or voids is less than the mean free path of an air molecule at NTP, i.e. of the order of 100 nm or smaller. A material which is microporous in this sense will exhibit very low transfer of heat by air conduction (that is, due to collisions between air molecules). Such microporous materials include aerogel, which is a gel in which the liquid phase has been replaced by a gaseous phase in such a way as to avoid the shrinkage which would occur if the gel were dried directly from a liquid. A substantially identical structure can be obtained by controlled precipitation from solution, the temperature and pH being controlled during precipitation to obtain an open lattice precipitate. Other equivalent open lattice structures include pyrogenic (fumed) and electro-thermal types in which a substantial proportion of the particles have an ultimate particle size less than 100 nm. Any of these materials, based, for example on silica, alumina, other metal oxides, or carbon, may be used to prepare a composition which is microporous as defined above. An opacifier that is used to opacify heat radiation is typically added, as well as some fiber, for instance glass fiber. Optionally a binder may be added to provide increased strength, in which case a heat treatment may be necessary in order to cure the binder.

[0007] Panels consisting of a core of microporous insulation material contained within an envelope in which is created a tensile strain have particularly good handleability and are described, for example, in GB-A-1 350 661. In the described process, an envelope is formed consisting, for example, of two rectangular sheets of porous woven glass cloth located on top of one another and sewn together around three sides. Powdered microporous insulation material is poured into the envelope and the envelope is then sealed completely. The resulting filled envelope is then subjected to compaction between opposing plates of a press, during which operation there is a build up of pressure within the envelope as the air within the insulation material is expelled through the woven glass cloth. A tensile strain is thereby created in the glass cloth envelope. Bonding of the envelope to the compacted insulation material occurs as a consequence of particles of the insulation material penetrating pores in the glass cloth of the envelope. The taut glass cloth provides rigidity for the resulting panel, which is substantially inflexible and unable to be subsequently wrapped around any curved object, such as a pipe.

[0008] It has also been proposed to provide a porous envelope of cotton, instead of woven glass fabric, to provide a flat panel which is somewhat less rigid, with the slight resultant flexibility enabling the panel to be shaped to fit some contoured surfaces. However, such cotton fabric has hitherto been of woven form, in the same way as glass cloth, and the resulting panel could not be described as flexible to the extent of being able to be wrapped around a pipe of, for example, about 219 mm diameter.

[0009] Various means have been adopted to make panels which are more flexible. The panels may be made to conform to an irregular shaped surface by a sewing operation through the panels to cause the envelope material on one major surface to become stitched to envelope material on the opposite major surface. The compacted microporous insulation remains contained between the surface covering sheets of the envelope material. The sewing operation through the panel may be carried out to produce a rectangular lattice pattern such that a quilted form of panel results. Similarly, an overstitched form of a panel may be produced. Flexible panels in quilted form and overstitched form are commercially available under the tradename Microtherm® Quilted and Overstitched from Promat in Belgium. However, these prior art methods of quilting and overstitching involve complex manufacturing processes. Moreover, the thickness of quilted and overstitched flexible panels is normally available in the thickness range from 3 to 10 mm, and up to 15 mm thickness upon request. In order to arrive at sufficient insulation, a customer may need to apply a plurality of layers of these materials.

[0010] A further proposal to render panels flexible is known from US5,792,540. It is therein proposed to use an envelope of porous stretchable material, at least in part, i.e. for one of both facer layers. With this proposal, the panel with a thickness of up to 15 mm may be draped around a pipe, having, for example, a diameter of about 219 mm. This thickness is at best marginally larger than the maximum thickness of the quilted or overstitched form. However, this seems to come at the price of limited temperature stability. The porous stretchable material is essentially a knitted fabric consisting of interlocked loops of polyamide fibers. However, polyamide fibers and other polymer fiber material have only limited temperature stability. Many customers use insulation of microporous material that comprises an inorganic insulation powder at applications that require high temperature stability. Operation temperatures in the range of 400 to 800°C are common, for which reason Promat sells Microtherm® products with temperature stabilities of up to 1000°C and up to 1200°C. Moreover, use of inflammable products is often a requirement. Polyamide or other polymeric fibers do not meet these requirements, and hence their use is to be avoided or at least to be minimized.

[0011] SUMMARY OF THE INVENTION

[0012] It is therefore an object of the invention to provide an insulation panel comprising microporous insulation material which is or can be rendered flexible and which further is stable at temperatures in the range of 400 to 800°C or higher to meet customer requirements of operation. Preferably, such an insulation panel can be made in a thickness larger than the thicknesses of quilted or overstitched panels. Further objects relate to the manufacture of such a panel and the use thereof around or against an object with a curved surface, such as a pipe.

[0013] According to a first aspect of the invention, an insulation panel is provided that comprises an envelope and a core of compressed microporous insulation material within said envelope, which insulation panel extends in a first main direction and a second main direction and has a thickness wherein said envelope comprising a first facer and a second facer that are mutually attached on opposed sides of the insulation panel in said first main direction and in said second main direction, which microporous insulation material comprises an inorganic insulation powder, an opacifier and a fiber. The envelope comprises a flange on at least one of said opposed sides of the insulation panel in said first main direction, said flange embodied by said first and second facer material, wherein said first and second facer material are fixed to each other by means of a closure on a first and a second edge of said flange in said first main direction, said first edge delimiting said core of microporous insulation material, wherein the closure on the first edge of the flange is removable.

[0014] According to a second aspect of the invention, a method of manufacturing such an insulation panel is provided comprising the steps of (1) providing an envelope that comprises a first and a second facer, said envelope is provided with at least one flange and at least one opening, wherein said flange is defined by means of a removable closure mutually connecting said first and said second facer; (2) inserting microporous material into said envelope via said opening, said microporous material comprising an inorganic insulation powder, an opacifier and a fiber; (3) compressing said microporous material into a core of microporous material, and (4) closing said opening of the envelope to obtain the insulation panel.

[0015] According to a third aspect of the invention, a method of arranging an insulation panel at a curved surface is provided, comprising the steps of: (1) providing the insulation panel of the invention; (2) removing the removable closure, (3) pressing said insulation panel with a press, so that the core of microporous insulation material elongates into said opened flange, therewith obtaining a deformed insulation panel; and (4) fastening said deformed insulation panel at the curved surface.

[0016] In the invention, the envelope of the insulation panel is provided with a flange. The first edge of the flange is arranged as a removable closure, which may be removed after manufacture of the insulation panel (in the factory) or before installation of the panel (at the site of the customer or at the site of installation). Under exertion of pressure, the core of microporous material will deform and especially elongate. Therewith, it is rendered flexible, or at least sufficiently flexible to be draped around a pipe or at another curved surface, such as a curved surface of a - typically cylindrical - vessel, the curved surface of a cone, etcetera. The inventor had initially thought that the core of microporous material would fully break and become useless under the exerted pressure. However, it was surprisingly found that the microporous material gets elongated without fracture that would render the deformed panel useless. In fact, it was generally understood in the art that compressed microporous material is no longer flowable due to its adhesion to the facer layers of the envelope.

[0017] In a preferred embodiment, the envelope is provided with a first and a second flange on opposed sides of the envelope in the first main direction. Applying two flanges facilitates that the core of microporous material may get elongated on two sides, thus facilitating a correct movement of the microporous material into the auxiliary spaces provided by the opened flanges. However, preliminary experiments have shown that the technology also works with a single flange. Use of a first and second flange is deemed particularly useful for panels having a longer length in the first main direction, for instance of 800 mm or more, such as 1000 mm or more.

[0018] In addition or instead of the provision of a second flange on the opposed side, the flange may be provided with an intermediate closure, which is again a removable closure. This intermediate closure is arranged between the first edge and the second edge of the flange. In this manner, a customer may decide how much extension is desired, for instance in view of variations in the diameter of the pipes to be insulated. Furthermore, in the event of applying several layers of insulation around a pipe, the circumference at a third or fourth insulation layer will be somewhat larger than the circumference at the pipe surface. The presence of one or more intermediate closures then enables the customer to achieve the correct circumference.

[0019] In a further embodiment, the thickness of the core of microporous insulation material is at least 12 mm. Preferably, the thickness is at least 16 mm, or even at least 20 mm, such as up to 30 mm. Thicknesses of 30 mm or more are also feasible. It will be understood that an increased thickness leads to greater stiffness. Therefore, very big thicknesses of 30 mm or more are recommended for objects with more gradual curves. One may think of pipes with larger diameters, reactor vessels and / or heating vessels and the like. The provision of insulation panels with a larger thickness has the advantage that less layers are needed to arrive at a predefined insulation thickness.

[0020] In a preferred embodiment, the facer layers of the envelope of the insulation panel are made of glass cloth, such as woven glass fabric. For some applications with less requirements on temperature stability cotton, a mixture of glass and cotton or even certain polymers could be used alternatively. The preferred inorganic insulation powder is pyrogenic silica, but mixtures of pyrogenic silica and precipitated silica, pyrogenic alumina or mixtures of pyrogenic silica and pyrogenic alumina may be used as well. Opacifiers are well known, such as titanium oxide, especially in its rutile form, silicon carbide, carbon black, zirconium silicate and the like. Opacifiers and inorganic insulation powders and filler if any are particulate materials which are mixed in dry form with fiber. Suitable fibers include glass fibers, alumina fibers, silica fibers, alkaline earth silicate fibers. Glass fibers are most common, whereas alumina fibers are in use in microporous materials requiring temperature stability of higher than 1000°C. Fillers may be added if so desired. A binder is typically not necessary. Fiber content in the microporous material is for instance from 1 to 8%, such as from 2 to 6% by weight. 3-5% is deemed common. The amount of opacifier is generally up to about 50% by weight, preferably in the range of 10-40% by weight, and it further depends on the selected opacifier. The inorganic insulation powder is preferably present in an amount of at least 50% by weight. The density of the core of compressed microporous material is suitably in the range of 100 and 500 kg / m3, such as in between of 150 to 400 kg / m3, and typically in the range of 200 to 320 kg / m3for a material comprising pyrogenic silica and from 300 to 420 kg / m3for a material comprising pyrogenic alumina. It is deemed an advantage of the present invention that a conventional microporous insulation material may be applied without need for modification. Most preferably, the insulation panel is so-called semi-rigid, such as the insulation panel sold by Promat under the tradename Microtherm® Panel.

[0021] It is an advantage of the panel of the present invention in comparison to flexible panels in quilted or overstitched form that the thermal conductivity of the panel is lower, even at equal thickness and densities. This applies especially to higher temperatures, such as at 600°C. At this temperature the panel form has a mean thermal conductivity of 0.031 W / m.K, whereas overstitched and quilted panel forms have a mean thermal conductivity of 0.038 W / m.K and 0.039 W / m.K respectively. These data are based on a microporous material comprising pyrogenic silica, rutile and glass fibers as commercially available from Promat. While the elongation may slightly increase the thermal conductivity of the panel form, it is foreseen that the increase will be limited. Hence, the panel of the present invention may not merely be more efficient in manufacturing, but also may give better thermal performance than said quilted and overstitched forms, even at equal thickness.

[0022] In one advantageous form, the length of the flange is at most 10% of the length of the core of microporous material, for instance between 5 and 10%. The length is herein expressed as the extension in the first main direction. It is foreseen, that the flange extends over the entire width (i.e. second main direction) of the panel, even though this is not deemed strictly necessary. In the event that the envelope comprises a first and a second flange, the length of each flange may be reduced; the combined length of the flanges could be 10% or 15% of the length of the core of microporous material. The length of said core is understood as the distance of a compartment of the envelope in which the core of microporous material is present prior to elongation of the microporous material during pressing following removal of one or more removable closures. In a further embodiment, the panel may be subjected to steam drying following its compression and the closure of the envelope. Steam drying of microporous material is known per se, see Example 1 of EP0194870A1, and typically involves a treatment with steam in an autoclave during 1 or more hours, which may be followed by a heat treatment, for instance at 125°C during 24 hours. Steam drying will increase the flexural strength and hence facilitate that the material may be deformed without breaking significantly.

[0023] The removable closure may be implemented in different ways. A preferred implementation is deemed the use of sewing to create a seam. An example hereof is stitching resulting in a stitch. This implementation has the advantage of being well-known and industrially implemented for panels of microporous materials. The seam or stitch is based on a thread that can be easily removed. If so desired, the thread may be provided with a handling part. Such handling part may be a loose end, a knot, a loop, a thickened portion, a hanger fixed to an end of the thread, and the like. The handling part may additionally or alternatively include a marker, so as to facilitate where the removable closure can be removed. Beyond the option of a hanger, the end of the thread may for instance be colored. In another implementation, the removable closure may be provided as an adhesive of which the adhesion force diminishes upon temperature increase.

[0024] In view of its properties, the mere removal of the removable closure is not sufficient to let the microporous material flow or elongate. In fact, the core of compressed microporous material is a body. In early patents of the 1970s and 1980s, reference is also made to a block of microporous material. It is only upon application of pressure that elongation will occur. The pressing force of a steel pipe was found sufficient in a preliminary experiment. This fact implies that the removable closure may be removed by the manufacturer of the panel rather than by a customer if so desired.

[0025] It is observed for sake of clarity that any of the above mentioned embodiment and any implementation as specified in the following figure description and / or the dependent claims applies to any and all aspects of the invention, even if not mentioned explicitly.

[0026] BRIEF INTRODUCTION OF THE FIGURES

[0027] These and other aspects of the invention will hereinafter be discussed with reference to the figures, which are purely diagrammatical in nature and not drawn to scale. Equal reference numerals in different figures refer to equal or corresponding parts. Therein:

[0028] Fig. 1 shows in cross-sectional, diagrammatical view a first embodiment of the insulation panel of the invention, wherein the insulation panel is in an initial state;

[0029] Fig. 2 shows in cross-sectional, diagrammatical view the insulation panel of the first embodiment, wherein the insulation panel is in a second, intermediate state;

[0030] Fig. 3 shows in cross-sectional, diagrammatical view a second embodiment of the insulation panel of the invention, wherein the insulation panel is in an initial state;

[0031] Fig. 4a-4c show in diagrammatical view the insulation panel of the first embodiment in three consecutive states: the intermediate state, during pressing an finally arranged on a curved surface in a final state.

[0032] DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

[0033] The figures are not drawn to scale and purely diagrammatical.

[0034] Figure 1 shows in a cross-sectional view an insulation panel 100 according to a first embodiment. The insulation panel 100 comprises an envelope 20, within with a core of compressed microporous insulation material 10 is present. The microporous insulation material is for instance a dry mixture of 3% glass fibers, 33% titanium oxide and the remainder pyrogenic silica. The microporous insulation material has been compressed after its insertion into the envelope, according to methods known in the art and for instance described in US5,792,540. The insulation panel 100 has for instance a length in its first main direction a of 700 mm, and a width in its second main direction of 450 mm. Said extension in the second direction is not shown in the figure. In the illustrated embodiment, the entire panel 100 has the same dimensions in the second main direction. The illustrated insulation panel furthermore has a thickness d, which is in one example 16 mm, but may alternatively be 20 mm or 24 mm or the like. The envelope 20 of the insulation panel 100 comprises a first facer layer 21 and a second facer layer 22. Typically, this is embodied as a woven glass cloth. While reference is made herein to facer layers 21, 22, it is not excluded that the facers comprise more than a single layer. The two facer layers 21, 22 are mutually attached at the edges of the panel 100, in stitched edge 25. While not shown in the figures, it will be understood that such a stitched edge 25 extends on the lateral outside of the insulation panel 100, so as to ensure that the insulation panel 100 is sealed. The manufacture of such stitched edge 25 is by means of sewing. Any other implementation that a stitched edge is not excluded.

[0035] According to the invention, the insulation panel 100 is provided with a flange 30. The flange 30 is part of the envelope 20, in the sense that it is formed from the first and the second facer layer 21, 22. Thereto, the first and the second layer are mutually connected. This connection is done at their opposed first edge 31 and second edge 32. The first edge 31 is arranged closer to the core of compressed microporous insulation material than the second edge 32. In fact, the first edge forms in the shown, initial state of the insulation panel 100, a delimitation of a compartment in which the core of microporous material is present. The second edge 32 is the ultimate edge of the insulation panel 100. The first edge 31 is implemented in a manner that it forms a removable closure. This means that a customer or an employee in a factory is able to remove said closure without damaging or destroying the insulation panel 100 or part thereof. In one preferred implementation, the first edge is made as a seam or stitch by sewing. The seam would normally extend into the second direction, parallel to the shown portion of the stitched edge 25.

[0036] Figure 2 shows the same insulation panel 100 in a second, intermediate state. In this intermediate state, the removable closure at the first edge 31 has been removed. As a consequence, the flange 30 is no longer just a flange, but may open up to provide an auxiliary space 35. It is observed that the drawn shape of the auxiliary space 35 is shown for sake of illustration and does not necessarily correspond to physical reality. It could be that the auxiliary space 35 is just minimal and that the first and second facer layers 21, 22 are still adjacent to each other. As the core 10 of compressed microporous insulation material acts as a single body, there is not a tendency of this core to displace into the auxiliary space.

[0037] Fig. 4a-4c show diagrammatically, how the insulation panel 100 may be transferred from its second, intermediate state into its final state, as shown in Fig. 4c. In this final state, the core 10 of compressed microporous insulation material has been elongated and fills the auxiliary space 35 in part of in its entirety. Typically, the elongated core 10 would fill the auxiliary space 35 in its entirety, i.e. to extend to the second edge 32 of the flange 30. However, dependent on for instance exerted pressure, thickness of the core 10, the chosen microporous material, this may not need be the case always.

[0038] Fig. 4a shows the second intermediate state of the insulation panel 100, and ready for the pressing that will lead to deformation. Thereto, a press or pressing object 200 is put onto the insulation panel 100, which itself lies on a table 250. The pressing object 200 is in this illustrated embodiment a pipe, and preferably a pipe of steel, other metal or alloy or any other material such as ceramics. In the preferred embodiment shown, the pressing object 200 is the same as the object at which curved surface the deformed insulation panel 100 is to be arranged. This is however not deemed strictly necessary.

[0039] Fig. 4b shows the insulation panel 100 during the pressing operation. Therein, the pressing object 200 rolls over the insulation panel 100, and as shown in Fig. 4b, the insulation panel 100 is wrapped around the pressing object 200. In order for the wrapping, the insulation panel 100 may be attached to the pressing object 200, for instance at one edge of the insulation panel 100. The arrow indicates the first main direction and furthermore indicates how the core 10 of microporous insulation material will be elongated into the auxiliary space 35.

[0040] Fig. 4c shows the pressing object 200 with the insulation panel 100 wrapped around it. It is now visible, that the auxiliary space 35 has been filled up by the elongated core. Therewith, the insulation panel 100 is in its final state. In the illustrated configuration, the insulation panel forms a single turn around the pressing object 200, with the stitched edge 25 and the second edge 32 of the flange approaching each other. While it is deemed preferred to generate a single turn instead of one and a half turn, the latter arrangement is not excluded. However, a single turn facilitates to provision of a further insulation panel thereon as a second turn in a most uniform manner. In case that a further insulation panel would be applied on the first turn, it is deemed preferably that the opposed edges 25, 32 will be located at a different position, so as to prevent alignment of the edges and creating of a kind of heat bridge or leakage line where insulation is absent or reduced. It is evidently not excluded that such a further insulation panel is of a different type that the insulation panel 100 wrapped around the object 200 as a first turn. Such insulation panel of a different type may be an insulation panel of microporous insulation in a different form, but alternatively an insulation panel comprises different material such as mineral wool. Moreover, it is not excluded that another insulation panel would be present between the object 200 and the insulation panel 100 applied as a first turn. Such other insulation panel could for instance be another, more flexible insulation panel of microporous material, such as an overstitched panel, a flexible insulation panel or the like. In case that there would be merely a single insulation panel 100 wrapped around the object 200, some overlap of the edges of the panel is deemed preferable. The insulation panel 100 can then be fastened to the object 200 in manner known in the art.

[0041] Fig. 3 shows the insulation panel 101 of a second embodiment. In this second embodiment, the insulation panel 101 is provided with a first flange 30 and a second flange 130 on opposed sides of the insulation panel, i.e. with the core 10 of compressed microporous insulation material in between of the flanges 30, 130. The second flange 130 has a first edge 131 and a second edge 132. Again the first edge 131 constitutes a removable closure, whereas the second edge 132 constitutes a permanent closure with the function to seal the insulation panel 101.

Claims

8Claims1. Insulation panel comprising an envelope and a core of compressed microporous insulation material within said envelope, which insulation panel extends in a first main direction and a second main direction and has a thickness wherein said envelope comprising a first facer and a second facer that are mutually attached on opposed sides of the insulation panel in said first main direction and in said second main direction, which microporous insulation material comprises an inorganic insulation powder, an opacifier and a fiber, wherein the envelope comprises a flange on at least one of said opposed sides of the insulation panel in said first main direction, said flange embodied by said first and second facer material, wherein said first and second facer material are fixed to each other by means of a closure on a first and a second edge of said flange in said first main direction, said first edge delimiting said core of microporous insulation material, wherein the closure on the first edge of the flange is removable.

2. Insulation panel as claimed in claim 1, wherein the closure on the first edge is embodied as a seam, for instance a stitch.

3. Insulation panel as claimed in claim 1 or 2, wherein the panel has a thickness in the range of 12 to 50 mm.

4. Insulation panel as claimed in any of the preceding claims, wherein the inorganic insulation powder is selected from the group comprising pyrogenic silica, pyrogenic alumina, precipitated silica, precipitated alumina and mixtures thereof.

5. Insulation panel as claimed in any of the preceding claims, wherein the core of microporous insulation material has a density in the range of 100 to 500 kg / m3, preferably 200 to 420 kg / m3, which density is measured prior to removal of said removable closure on the first edge of the flange.

6. Insulation panel as claimed in any of the preceding claims, wherein the flange has a length in the first main direction, which is from 2 to 20%, preferably from 3 to 10% of a length of said core of microporous material, when measured prior to removal of said removable closure on the first edge of the flange.

7. A method of manufacturing an insulation panel as claimed in any of the preceding claims, comprising the steps of:Providing an envelope that comprises a first and a second facer, said envelope is provided with at least one flange and at least one opening, wherein said flange is defined by means of a removable closure mutually connecting said first and said second facer;Inserting microporous material into said envelope via said opening, said microporous material comprising an inorganic insulation powder, an opacifier and a fiber;Compressing said microporous material into a core of microporous material, and Closing said opening of the envelope to obtain the insulation panel.

98. A method of arranging an insulation panel at a curved surface, comprising the steps of:Providing the insulation panel as claimed in any of the claims 1 to 6;Removing the removable closure, andPressing said insulation panel with a press, so that the core of microporous insulation material elongates into said opened flange, therewith obtaining a deformed insulation panel;Fastening said deformed insulation panel at the curved surface.

9. The method as claimed in claim 8, wherein the press is a curved object such as a pipe.

10. The method as claimed in claim 9, wherein the curved surface is a surface of said curved object.

11. A curved insulation panel obtainable with the method as claimed in any of the claims 8 to 10.

12. A curved object insulated with the curved insulation panel as claimed in claim 11.

13. An insulation panel obtained by removal of at least one removable closure from the insulation panel as claimed in any of the claims 1 to 6.

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