LU93135B1 - Thermal insulation system - Google Patents

Abstract

The invention proposes a thermal insulation system and method for heat-insulating the surface of a device while protecting it from corrosion, in which the system comprises an insulating layer covering said surface, the insulating layer possibly being to be covered with an outer protective layer, wherein the thermal insulation system comprises at least in certain regions between the surface of the device and the insulating layer an air space in contact with a discrete number of exchange zones with the external atmosphere, the exchange zones with the external atmosphere comprising a polymer membrane permeable to water vapor.

Description

CALORIFUGEAGE SYSTEM

Technical Field [0001] The present invention relates generally to heat insulation.

STATE OF THE ART [0002] Born after the last world war, the field of thermal insulation took off in the wake of the first oil crisis of 1973. It then became of paramount importance to isolate the thousands of meters of pipelines, balloons and tanks of which the oil refining centers are constituted. But also, boilers, steel plants, nuclear power plants, incineration centers with their heat recovery, the food industry have become the main outlets for this area of insulation.

In practice, the insulation of pipes or other industrial process systems involving the transfer of a coolant or coolant must face the following main problems: • optimization of the insulation (thickness and type) to ensure maximum insulation , • mechanical and fire resistance, • lowest possible cost.

The conventional configuration of a thermal insulation is an insulating material attached to its support and a single outer protective shell (stainless steel, steel, aluminum, laminated PVC). This outer shell provides mechanical protection against shocks and ensures airtightness and water to not degrade the insulating layer (further is referred to as the first skin).

As any system ages, water seepage may occur locally due to degradation of the outer sheet, an inadequate implementation of the thermal insulation system (water drop incorrectly positioned screw assembly not sufficiently functional, etc.).

Local water infiltration will result in polluting the insulation reducing its effectiveness and more serious, to create optimum conditions for accelerated corrosion (phenomenon called corrosion underlying the insulation). This is an important and very real problem. It was reported to me that a company like Statoil (Norway) was spending at least 50% of its maintenance budget on repairs due to underlying corrosion problems. .

In practice, this means that the installation must be shut down, the corroded sections replaced or repaired, etc., the costs related to these problems are enormous.

The current solutions are very limited: • increased protection of the subsystem subject to heat insulation, that is to say protection of metal pipes by special paint, resin, etc.. This can limit the damage and delay the corrosion phenomenon, but the causes are still present, moreover the degradation of the insulation following the introduction will have the consequence to increase the heat losses, • holes located on the lower face to make Locally escape an excess of moisture, it is extremely basic as a solution, I also express reservations about the efficiency ..., to be effective it would take a multitude of holes drilled considering that water can condense at a certain moment and evacuate by gravity. A large number of holes also means missing insulation and therefore heat losses.

OBJECT OF THE INVENTION [0009] The object of the present invention is to remedy the above problems and aims in particular to propose a thermal insulation structure allowing the elimination of corrosion under an insulator following an unwanted introduction of water. .

GENERAL DESCRIPTION OF THE INVENTION [0010] With these objectives in view, the object of the invention is the development of a double-skin thermal insulation system with a hybrid metal-membrane polymer system which allows punctually to reject the moisture or vapor of the skin. water to the outside. In particular, the invention proposes in a first aspect, a thermal insulation system for heat-insulating the surface of a device while protecting it from corrosion, wherein the system comprises an insulating layer covering said surface, the layer of insulation which may optionally be covered with an outer protective layer, wherein the thermal insulation system comprises at least in certain regions between the surface of the device and the insulating layer an air gap in contact with a discrete number of exchange zones with the external atmosphere, the exchange zones with the external atmosphere comprising a polymer membrane permeable to water vapor.

In a preferred embodiment, the heat insulating device comprises pipes or conduits for the transfer of heat transfer fluids or refrigerants.

Preferably, the polymer membrane is a unidirectional exchange polymer membrane and it can be expanded or not.

The space for the air gap between the surface of the device and the insulating layer can be made for example by means of spacers, embossings or by means of indentations arranged in the insulation layer of the side of the surface of the device or by any other appropriate means.

The air gap is preferably dimensioned so as to allow a laminar, semi-turbulent or turbulent air displacement regime, particularly laminar to semi-turbulent manner.

In a particularly preferred embodiment, the thermal insulation system is a thermal insulation system to isolate a pipe while protecting it from corrosion, the system comprising a number of insulating units connectable by their ends, each connectable thermal insulation unit. comprising an insulation layer of suitable section for fixing around the pipe with sufficient space for an air gap between the surface of the pipe and the insulating layer, each insulation unit comprising at least one exchange zone with the outside atmosphere, preferably at one of their ends.

In a second aspect, the invention provides a heat-insulating method for insulating the surface of a device while protecting it from corrosion, comprising the use of a system according to the invention.

In a third aspect, the invention contemplates the use of a thermal insulation system according to the invention to insulate the surface of a device while protecting it from corrosion.

Detailed Description [0018] Other features and characteristics of the invention will become apparent from the detailed description below.

[0019] Preliminaries: the assembly of the outer shell (called first skin) is section by section (unit per unit) in the longitudinal direction with a generally male and female side. There are different types of assemblies or connections, but the invention is not only suitable for types widely used in the industry. On the contrary, the invention can be realized in many ways depending on the type of device to insulate and protect against corrosion.

The explanation for this system and to facilitate the exercise does not include other specific cases, such as risers, valve boxes, etc., but the concept is globally applicable everywhere with a geometric adaptation of the system. metal-polymer membrane assembly.

[0021] Functional description of the system In general, it is necessary to create a channel (an air gap) as close as possible to the pipework allowing air circulation and this continuously to the point where the Moisture will be extracted / exchanged with the outside atmosphere via the membrane, this can be done in various non-exhaustive ways: A) Such as a double metal skin or perforated plastic material around the coolant pipe, spacers or spacers. Embossing in the double skin generates sufficient space for the displacement of an air space in a laminar-semi-turbulent-turbulent regime (Fig. 1). B) This air gap can also be created by indenting the insulation around its circumference (Fig. 2), the spacer system is no longer needed.

The insulation is placed in the case A between the two skins and in the case B between the pipe and the first skin.

It is now necessary to create points of contact between a polymer membrane and the air gap charged with water vapor, this contact will allow the evacuation of the interior to the outside of this excess moisture. The diaphragm works in one direction only and the external moisture can not flow inwards (Fig. 3). The membrane is also the subject of a mechanical protection through the 1st skin, the latter having to have non-deterministic openings (round, square, oval, etc.) to always allow contact outside air - membrane . The membrane may be circumferentially complete or incomplete and longitudinal with respect to the first skin.

The polymer membrane must optimize the following characteristics: • membrane effect and unidirectional exchange with the outside, • insulating factor, with expanded form of the polymer, but not necessarily, • mechanical resistance and fire.

BRIEF DESCRIPTION OF THE DRAWINGS [0026] Other features and characteristics of the invention will become apparent from the appended drawings:

Fig. 1 shows two embodiments of the system according to the invention in longitudinal section.

Fig. 2 shows a variant of the system according to the invention in cross section and longitudinal.

Fig. 3 illustrates the exchange between the air gap and the outside atmosphere.

Claims (10)

1. Thermal insulation system for heat-insulating the surface of a device while protecting it from corrosion, in which the system comprises an insulating layer covering said surface, the layer of insulation possibly being covered with a layer in which the thermal insulation system comprises at least in certain regions between the surface of the device and the insulation layer an air space in contact with a discrete number of exchange zones with the external atmosphere, exchange zones with the external atmosphere comprising a polymer membrane permeable to water vapor. 2. thermal insulation system according to claim 1, wherein the device comprises pipes or conduits for the transfer of heat transfer fluids or coolants. The thermal insulation system of claim 1 or 2, wherein the polymeric membrane is a unidirectional exchange polymer membrane. The thermal insulation system according to any one of the preceding claims, wherein the polymeric membrane is expanded. The thermal insulation system of any preceding claim, wherein the space for the air gap between the device surface and the insulation layer is provided by means of spacers. 6. Thermal insulation system according to any one of the preceding claims, wherein the space for the air gap between the surface of the device and the insulating layer is achieved by means of indentations arranged in the insulation layer. on the side of the device surface. 7. Thermal insulation system according to any one of the preceding claims, wherein the air gap is sized to obtain a laminar air flow regime, semi-turbulent or turbulent, preferably laminar to semi-turbulent. A thermal insulation system according to any one of the preceding claims, which is a lagging system for isolating a pipe, the system comprising a number of end connectable thermal insulation units, each connectable heat insulation unit comprising a thermal insulation layer. insulation of appropriate section for fixing around the pipe with sufficient space for an air gap between the surface of the pipe and the layer of insulation, each insulation unit comprising at least one exchange zone with the external atmosphere, preferably at one of their ends. A heat insulation method for heat insulating the surface of a device while protecting it from corrosion, comprising the use of a system according to any one of claims 1 to 8. 10. Use of a thermal insulation system according to any one of claims 1 to 8 to insulate the surface of a device while protecting it from corrosion.