PIPE SECTION FOR INSULATION OF PIPES, ITS MANUFACTURING METHOD AND SYSTEM

One object of this invention is a pipe section for insulation of pipes, consisting essentially of mineral wool which contains at least a binder and possibly also other additives.

A second object of this invention is a manufacturing method for a pipe section of mineral wool for insulation of pipes, wherein a block of cured pipe section, emerging from the production line and consisting essentially of mineral wool which contains at least a binder and possibly also other additives, is brought to its final shape by cutting off its uneven ends.

Another object of this invention is a manufacturing system for a pipe section of mineral wool for insulation of pipes, wherein a block of cured pipe section, emerging from the production line and consisting essentially of mineral wool which contains at least a binder and possibly also other additives, is brought to its final shape by cutting off its uneven ends.

In this application, the term "mineral wool mat" is used in reference to both a conventionally manufactured, still uncured mineral wool mat and a thinner segment (lamella) of the mat obtained by cutting from such a mineral wool mat.

Currently employed manufacturing methods for blocks of pipe section produce lots of material waste. The largest amounts of waste originate from the ends of blocks of pipe section, which are cut off for providing the blocks of pipe section with trimmed ends. This amount of waste is about 10% of the amount of used raw material. This waste material is currently used as a raw material for blowing wool and HT bricks, but some of this material is also shipped to a landfill. The waste originating from machines which produce or process other mineral wool products would be enough for providing a

sufficient amount of raw material for blowing wool and HT brick. If the ends could be completely recycled in the production of blocks of pipe section, the waste load could be reduced considerably. At the same time, less raw wool would be needed for the manufacture of blocks of pipe section.

If the cut-off ends of blocks of pipe section could be completely recycled in a manufacturing method for blocks of pipe section, the transport costs could also be reduced. The cut-off ends would not require shipping or conveying to manufacturing sites for other products away from the manufacturing site of pipe sections by being reusable in the same method or process that creates them.

An objective of this invention is to eliminate the foregoing drawbacks and to present a pipe section, its manufacturing method and system, whereby material waste problems can be mitigated or eliminated almost totally or even completely.

In view of the above objective, the pipe section of the invention is characterized in that at least a part of the mineral wool of the pipe section and/or the binder and/or possible other additives contained in the mineral wool consist of recycled material originating from material wastes produced by the manufacturing process of the pipe section itself.

On the other hand, the method of the invention is characterized in that at least a part of the cut-off ends of the blocks of pipe section, along with all materials contained therein, are reused in at least one previous manufacturing stage of said blocks of pipe section by adding the same on top of and/or to a still uncured mineral wool material.

The system of the invention is characterized in that, in order to reuse the cut-off ends of the blocks of pipe section in at least one previous stage of the process of manufacturing said blocks of pipe section, the system comprises a

conveying device for conveying the cut-off ends to at least one previous stage of manufacture, at least one shredder for tearing the cut-off ends to pieces, at least one shredder having a spreader provided in connection therewith for scattering the shredded pieces to and/or on top of a still uncured mineral wool material.

In addition to the above, the invention relates also to the reuse of mineral wool waste, produced in the manufacture of a pipe section, as raw material in a previous stage of said manufacture for reducing the consumption of raw material and the generation of mineral wool waste.

In one preferred embodiment of the pipe section according to the invention, the recycled material consists of cut-off uneven ends of a cured block of pipe section emerging from the production line of the pipe section itself, consisting essentially of mineral wool which contains at least a binder but possibly also other additives, said ends having been shredded into loose material. The portion of recycled material waste in the total material of a finished pipe section is preferably between 0 and about 15%, more preferably about 5 to 10%.

In one preferred embodiment of the method according to the invention, the cut-off ends of the section blocks, along with all materials contained therein, are reused almost totally or even completely. It is further preferred that utilization of the cut-off ends as a manufacturing material in an earlier manufacturing stage be performed as a continuous process.

In a second preferred embodiment of the method according to the invention, the cut-off ends are recovered, chopped to pieces and returned to an earlier stage of the production line on top of and/or to a still uncured, binder containing mineral wool material for reuse. This can be performed as a continuous process, as well. It is further preferred that the still uncured mineral wool material be in the form of a mineral wool mat or, alternatively,

it is also preferred that the still uncured mineral wool material be made up of shredded wool (this applies in the case of constructing a pipe section in a space between an inner core and an outer mould). In the event that the employed uncured mineral wool comprises a mineral wool mat, it is preferred that chopped, cut-off ends be spread across said mineral mat prior to winding it around a core and working it substantially into the shape of a pipe section. The chopped, cut-off ends are preferably spread over said mineral wool mat substantially across its entire breadth, yet in such a way that no chopped, cut-off ends at all shall be spread over the leading and trailing portions of the mat. In order for the chopped mineral wool material to remain stuck on the mat upon its winding, it is preferred that the chopped mineral wool material be pressed, e.g. with a press roll, against the mineral wool mat prior to the winding. The cut-off ends are chopped to pieces with the size of preferably about 3-15 mm. The chopping is preferably performed by tearing the same first to coarse pieces and subsequently to finer pieces. The shredding to finer pieces can be preferably performed in a joint operation with the spreading of recycled material on top of and/or to the still uncured mineral wool material. The fire safety of a pipe section can be enhanced by using an additive in the form of a fire retardant. It is also preferred that, in addition to recyclable materials, there will be other additives and/or fire retardants supplied from outside the manufacturing process of the pipe section, either separately, in a composition or in a mixture with the reusable chopped ends. Examples of additives useful as fire retardants are gypsum, slaked lime, calcium carbonate, calcium sulphate hemihydrate, dolomite, aluminium hydroxide, aluminium sulphate, magnesium hydroxide, magnesium carbonate, montmorillonite, bentonite. Examples of additives useful as fire retardants which expand at a high temperature are vermiculite, perlite, pumice, as well as various types of expansible clay.

The system of the invention, in one preferred embodiment thereof, is provided with a shredder which consists of a coarse shredder and a fine

shredder. In the system of the invention, the conveying device can preferably be a belt conveyor or a tube system.

In another preferred embodiment of the system according to the invention, said still uncured mineral wool material being in the form of a mineral wool mat, the spreader is arranged above the still uncured mat of mineral wool material, and that downstream of the spreader in the traveling direction of the mat is disposed a press roll for pressing the material spread across the mat to a secure contact with the surface of the mat for keeping it there when winding the mat around a core in the actual section forming process.

The invention will now be described more closely with reference to the accompanying drawings, in which

fig. 1 shows in a schematic view one system implementing the method of the invention, and

fig. 2 shows in a schematic view another system implementing the method of the invention.

In the solutions depicted here by way of examples, the employed mineral wool mat comprises a thinner mat (3) obtained by cutting from a conventionally manufactured and still uncured mineral wool mat, emerging directly from a basic wool line and containing a binder and a fire retardant.

In the system shown in fig. 1, blocks 1 of pipe section are brought to the final shape thereof by cutting off uneven ends 2 thereof in the final manufacturing stage of the blocks 1 of pipe section by means of cutters 4a and 4b.

The cut-off ends 2 are conveyed by belt conveyors 5, 6 to a store 7, which is arranged above a belt conveyor 8 conveying a still uncured mineral wool mat

3 prior to a winding operation 9 of the mineral wool mat 3. The store 7 has a downward converging circumference and comprises both a coarse shredder 10 for the coarse shredding of cut-off ends and a combined fine shredder/spreader 11 for comminuting a coarse-shredded material 12 and scattering the same on top of the mineral wool mat 3 traveling below the fine shredder/spreader 11.

The fine shredder/spreader 11 spreads the fine-shredded material 13 by a lateral action over the mat 3. This is further depicted by showing the coated mat of fig. 1 in a close-up a, in which the mat is seen from above. The shredded material 13 spread over the mat 3 is next pressed by a press roll 14 disposed on the belt conveyor 8 to a secure contact with the surface of the mat 3. The mat 3, coated with shredded material, is advanced further by a second belt conveyor 15 to a winding operation 9 taking place around a core 16, the manufacture of the block 1 of mineral wool section proceeding from here forward in a conventional manner.

Depicted in fig. 2 is another example of a practical application of the invention, in which the process is otherwise identical to that shown in fig. 1, except that, in this case, coarse shredder 10 is not disposed in the store of cut-off ends 2 as in the example of fig. 1, but is present as a separate unit at the bottom end of a drop pipe 17 right next to the end of a belt 5 carrying the cut-off ends 2 away.

A material 12, coarsely shredded by the coarse shredder 10, falls down on a second belt conveyor 18 by which the coarsely shredded material 12 is carried into a store 19. The downwardly 14 converging store 19 has its bottom end provided with a combined fine shredder/spreader 11 for scattering the comminuted material on top of the mineral wool mat 3. Henceforth, the manufacturing process of a block 1 of pipe section to be produced is consistent with the solution shown in fig. 1.

In the practical examples shown in figs. 1 and 2, the shredded material is spread over the mineral wool mat 3 evenly across its entire breadth, yet with no material spread over the leading and trailing portions of the mat 3. This enables providing a good internal and external surface for the block of pipe section and the added wool remains invisible between the wound-up layers. These particles must be pressed slightly against the mineral wool mat 3, as otherwise such particles do not remain stuck on top of the mat 3 in the process of winding.

The amount of raw material can be reduced by as much as the shredded material is increased. The portion of shredded material, in other words the cut-off ends 2, is about 15% of the consumption of raw material. The present invention of ours makes it now possible that machines for making blocks of pipe section would no longer have to produce waste wool at all.