WO2011048266A1

WO2011048266A1 - Insulation structure and method for insulating a structure

Info

Publication number: WO2011048266A1
Application number: PCT/FI2010/050813
Authority: WO
Inventors: Jari Sistonen
Original assignee: U-CONT Ltd Oy; U Cont Ltd Oy
Current assignee: U-CONT Ltd Oy; U Cont Ltd Oy
Priority date: 2009-10-19
Filing date: 2010-10-19
Publication date: 2011-04-28
Anticipated expiration: 2012-04-19
Also published as: FI20096073A0; SE1250491A1; NO342136B1; NO20120449A1; FI125764B; FI20096073L

Abstract

The invention relates to an insulation structure (21, 31) comprising an inner shell (2) for surrounding a material to be fitted into the insulation structure and at least two insulation volumes (5.1, 5.2, 5.3) with an adjustable thermal conductivity for a medium, arranged outside the inner shell. The invention also relates to a method for insulating a structure (21, 31), the structure comprising an inner shell (2) intended for surrounding a material to be fitted into the structure, which method comprises adjusting the thermal conductivity of at least two insulation volumes arranged outside the inner shell.

Description

INSULATION STRUCTURE AND METHOD FOR INSULATING A STRUCTURE

FIELD OF THE INVENTION The invention relates to an insulation structure and a method for insulating a structure. Particularly, but not solely, the invention relates to an insulated tank and/or storage and a method for adjusting the insulation capacity of a tank and/or storage. BACKGROUND OF THE INVENTION

As known, solid insulators are used as thermal insulators of storages and tanks. Typically, solid materials, such as fiber insulators or solidifying insulation foams, are used as insulation material in such structures. The insulating influence of solid insulation is dimensioned for the intended purpose of use.

The patent application publication US 2007/0181583 discloses a movable fuel tank comprising an inner shell and an outer shell. The purpose of the double wall structure of the tank is to make the tank safer in a forest environment.

SUMMARY

In accordance with a first aspect of the invention, an insulation structure is provided, comprising an inner shell to surround material to be fitted into the insulation structure. The insulation structure comprises at least one insulation volume having adjustable thermal conductivity for a medium, arranged outside the inner shell.

Preferably, the insulation structure comprises an inner shell surrounding a reception volume intended for a material to be fitted into the insulation structure, and the insulation structure comprises at least two insulation volumes for a medium separate from each other and having separately adjustable thermal conductivity, the at least two insulation volumes being arranged outside the inner shell so that the influence of the at least two insulation volumes is directed at significantly different locations of the same reception volume.

In accordance with a second aspect of the invention, a method is providedfor insulating a structure, the structure comprising an inner shell which is intended for surrounding a material to be fitted into the structure. The method comprises adjusting the thermal conductivity of at least one insulation volume arranged outside the inner shell. Preferably, a method is provided for insulating a structure, the structure comprising an inner shell which surrounds a reception volume intended for a material to be fitted into the structure, and the method comprises arranging at least two separate insulation volumes outside the inner shell so that the influence of the at least two insulation volumes is directed at significantly different locations of the same reception volume and separately adjusting the thermal conductivities of the at least two insulation volumes.

Preferably, the insulation structure comprises means for adjusting the thermal conductivity of the insulation volume. The insulation structure may comprise a number of separate insulation volumes which may be separately controllable.

In accordance with some embodiments, an apparatus comprises an insulation structure comprising an inner shell for surrounding a material to be fitted into the insulation structure. The insulation structure comprises at least one insulation volume having adjustable thermal conductivity for a medium, arranged outside the inner shell. The apparatus may comprise means for adjusting thermal conductivity. The apparatus may comprise a control device. The apparatus may comprise temperature sensors for the measurement of a temperature external and/or internal to the insulation structure.

Preferably, an inner surface of the inner shell opens in the direction of the material intended to be stored within the insulation structure. Preferably, the insulation structure comprises an outer shell which is fitted outside the inner shell and has an outer surface. Preferably, a space formed between the outer surface of the inner shell and the inner surface of the outer shell is at least partly formed as an insulation volume. Preferably, the insulation volume is at least partly fitted around the inner shell.

Preferably, an outer surface of the insulation volume is formed by the outer surface of the outer shell. Preferably, the outer surface of the insulation volume is at least partly arranged within the sphere of influence of the varying temperature of the environment. Preferably, the outer surface of the insulation volume is at least partly arranged within the sphere of influence of the temperature of a soil layer. In many cases, the temperature is even within the soil layer. In some cases, the temperature of a soil layer is evenly cool. In some cases, the temperature of a soil layer is evenly warm or hot. Preferably, the outer surface of the insulation volume is at least partly arranged within the sphere of influence of the temperature of groundwater. In some cases, the temperature of groundwater is evenly cool. The heat transfer of the insulation structure may be enhanced by locating at least part of the insulation volume in the area of flowing groundwater. At least part of the insulation volume or volumes may be located in the sphere of influence of a water system or a spring. The spring may be a cold or a hot spring.

Preferably, the outer surface of the insulation volume is arranged at least partly in the open air. Preferably, a collector of thermal radiation, such as a solar collector, is arranged on the outer surface of or outside the insulation volume to enhance heat transfer. The insulation structure may also be heated by other means, such as electric resistors or circulation of liquid. Circulation of liquid may also be used for cooling. The outer surface of the insulation volume may comprise a color or surface roughness enhancing heat transfer. The outer surface of the insulation volume may be matte-like.

Preferably, a mixing device for mixing the content of the insulation structure is arranged inside the insulation volume to enhance heat transfer. The mixing device may comprise a rotatable propeller or a pump. In accordance with some embodiments, the insulation structure is fitted into a tank and/or storage. The tank and/or storage may be of the self-supporting type. The tank and/or storage may be movable. The tank and/or storage may be of the container type. The tank and/or storage may comprise a cylindrical, spherical or angular form and a combination of at least some of these.

The tank and/or storage may be on ground level. The tank and/or storage may be partly or entirely underground. Preferably, at least part of the portion of the insulation structure above ground is equipped with an insulation volume having adjustable thermal conductivity for a medium, fitted outside the inner shell. Some underground part of the insulation structure may be equipped with a solid insulator. One end or both ends of a cylindrical tank may be equipped with a solid insulator. If there is an instrumentation cabinet or similar in connection with the end or shell of the tank, this area of the outer shell is not in direct connection with open air. The area of the outer shell of the tank and/or storage which is not directly in the sphere of influence of the varying temperature of the environment may be equipped with a solid insulator. Preferably, the insulation structure comprises a wall surrounding the material to be stored. The insulation structure may comprise an insulation volume having adjustable thermal conductivity for a medium, arranged in a wall outside the inner shell of the wall directed towards the material to be stored. Preferably, the wall comprises an outer shell, and the insulation volume is fitted between the inner and the outer shell of the wall.

The means for adjusting thermal conductivity may comprise at least one of the following: a medium pressure adjustment means, a medium density adjustment means, a medium amount adjustment means, a control device for conducting the medium into and/or out of the insulation volume, an adjustment means for adding the medium to the insulation volume and/or reducing the medium in the insulation volume, a pressure measurement means, a temperature measurement means. The means for adjusting thermal conductivity may comprise at least one of the following: an underpressure pump, a vacuum pump, a material transfer pump, a pressure pump, a pressurized gas source, a pressurized gas tank, a charging valve, a drain valve.

Preferably, the insulation structure comprises a control device. The control device enables controlling the means for adjusting thermal conductivity. The control device enables conducting the medium into and out of the insulation volume. The temperature inside the tank/storage may be measured. The temperature outside the tank/storage, i.e., the temperature of the environment may be measured. One or several temperature sensors may be arranged for measuring the temperature outside the insulation structure. One or several temperature sensors may be arranged for measuring the temperature inside the insulation structure. The temperature sensor(s) may be connected to the control device. The pressure in the insulation volume may be measured. One or several pressure sensors may be arranged in the insulation volume as a pressure measurement means.

The measured temperature and/or pressure values may be processed in the control device. An adjustment value for controlling an adjustment means may be determined in the control device on the basis of the measured temperature and/or pressure values. The control device can be used to conduct the medium into or out of the insulation volume depending on the temperature of the environment and/or of the contents of the insulation structure. Preferably, the insulation structure comprises a control device for controlling an adjustment means so that when the temperature of the environment is lower than that of the contents of the tank, the gaseous medium is reduced in the volume to cool the contents. Preferably, the insulation structure comprises a control device for controlling an adjustment means so that when the temperature of the environment decreases, a gaseous medium is reduced in the volume. Preferably, the insulation structure comprises a control device for controlling an adjustment means so that when the temperature of the environment is higher than that of the contents of the tank, a gaseous medium is reduced in the volume to heat the contents.

Preferably, the insulation structure comprises a control device for controlling an adjustment means so that when the temperature of the environment increases, a gaseous medium is reduced in the volume. Preferably, the insulation volume is pressure-tight. In accordance with some embodiments, the insulation structure comprises a pressure-tight volume arranged outside an inner shell for a medium to be pressurized and an adjustment means for the adjustable pressurizing of the medium to be fitted into the pressure-tight volume.

Preferably, the adjustment means comprises an underpressure pump for underpressurizing a gaseous medium. Preferably, the adjustment means comprises a pressure pump for overpressurizing a gaseous medium. Preferably, the tank comprises an outer shell, and the insulation volume is fitted between an inner and the outer shell.

Preferably, the medium is fitted to be moved into and out from the insulation volume depending on the temperature of the environment. In accordance with some embodiments, the medium is fitted to be moved into and out of the insulation volume depending on the direction of a change in the temperature of the environment.

The medium to be fitted into the insulation volume having adjustable thermal conductivity may comprise at least one of the following or a mixture of some of the following: a gas, a liquid, a pumpable medium, a viscous medium, air, water, a refrigerant, a constituent of crude oil, a hydrocarbon. Two media may be fitted into the insulation volume. Liquid and gaseous media may be fitted into the insulation volume. A gasifiable medium (e.g., a hydrocarbon, a refrigerant) may be fitted into the insulation volume. Changes to the thermal conductivity of the insulation volume may be effected by changing the pressure and/or amount of the medium. Typically, liquids have a higher thermal conductivity than gases. In order to increase the thermal conductivity of an insulator, the volume portion of liquid in the insulation volume may be increased at the expense of the volume portion of gas. The thermal conductivity of the insulation volume may be increased or enhanced by circulating liquid in the insulation volume. In order to decrease the thermal conductivity of the insulator, the volume portion of gas in the insulation volume may be increased at the expense of the volume portion of liquid. In accordance with some embodiments, when low insulation capacity is required, liquid is placed in the insulation volume, and when higher insulation capacity is required, the liquid or some liquid is removed from the insulation volume and a vacuum is sucked into the insulation volume. The amount of vacuum can be adjusted.

To increase the thermal conductivity, the density of the medium fitted into the insulation volume, such as a gas or a gas mixture, can be increased by increasing the pressure on the medium. Typically, the thermal conductivity of the medium increases when the density of the medium increases. Comparably, inversely, in order to decrease the thermal conductivity of the insulator, the density of the medium fitted into the insulation volume can be decreased by increasing the pressure on the medium, whereby the thermal conductivity of the medium decreases.

A heat conductive/insulating medium can be exchanged in the insulation volume to adjust the thermal conductivity of the insulating/heat conductive structure. The heat conductive/insulating medium in the insulating volume can be entirely exchanged for another medium to adjust the thermal conductivity of the insulating/heat conductive structure.

Preferably, the insulating capacity of the insulation of the tank is adjusted by changing the thermal conductivity of the insulation volume outside the inner shell.

Preferably, the insulating capacity of the insulation of the tank is adjusted by changing the pressure of the insulation volume outside the inner shell. A pressure corresponding to that of the environment can be arranged in the insulation volume.

Preferably, the insulating capacity of the insulation is increased by decreasing the pressure on the medium in the insulation volume. In accordance with some embodiments, an overpressure on the medium in the insulation volume is decreased. The insulation volume may be underpressurized. The underpressure in the insulation volume may be increased. A vacuum may be arranged in the insulation volume.

The value of the pressure arranged in the insulation volume, e.g., underpressure, depends on, among other things, the thickness and shape of the wall of the insulation volume, such as the distance between the inner and outer shell of the insulation volume.

Preferably, the insulating capacity of the insulation is decreased by increasing the pressure on the medium in the insulation volume. In accordance with some embodiments, the underpressure of the medium in the insulation volume is decreased. The insulation volume may be overpressurized. The overpressure in the insulation volume may be increased. The contents of the insulation structure may be cooled by decreasing the insulating capacity of the insulation volume when the temperature of the environment is lower than that of the contents of the insulation structure.

The contents of the insulation structure may be heated by increasing the insulating capacity of the insulation volume when the temperature of the environment is higher than that of the contents of the insulation structure.

The insulation structure may be fitted as part of a tank or a storage. The storage and/or tank may be intended for the storage of people, animals or goods. Equipment producing heat may be stored in the storage and/or tank. The storage and/or tank may be a storage of the process and/or food industry or a storage of agriculture. The storage and/or tank may contain, for example, equipment for energy distribution, electricity distribution, water distribution, sewerage, waste treatment, fuel distribution, data transfer or telecommunication networks. By means of the adjustable insulation, the temperature of the material stored in the tank or storage may be adjusted. The temperature of the material being stored may be increased and/or decreased. The temperature of the material to be stored may be kept even. The temperature of the environment, for example, the temperature prevailing in nature, can be used for increasing and/or decreasing the temperature of the material being stored. The variation in the temperature of the environment, for example, variation in daily temperature or seasonal variation of temperature can be utilized in the insulation of the tank. In accordance with some embodiments, by utilizing the daily temperature variation of the environment of the tank, the need for heating and/or cooling can be reduced. Adjustable insulation allows saving energy. The thermal expansion and/or thermal contraction of the material in the tank or storage may be decreased. Changes in the stress state of the structure of the tank may be decreased.

The principle of adjustable insulation, the insulation structure and the method presented in this description may be applied within the scope of, among other things, the process industry and food industry, as well as agriculture. By means of the insulation structure, the temperature of the material stored, the material fed into the process or being processed in the process may be decreased, maintained and increased in an energy-efficient manner.

In accordance with some embodiments, the tanks may be used as a tank for putrefaction, composting and fermentation processes. Thereby, the heating and cooling power obtained from the environment can be used in an energy-efficient manner in such biological processes. In a biological process, heat obtained from outside the tank may be used for activating a process, activating bacterial action, for example. When the process has been activated, the temperature of the contents of the tank may be cooled to maintain a suitable operational temperature for the process by transferring heat outside the tank if the temperature in the process increases excessively, for example, excessively for the action of the bacteria used in the process.

The heat energy available in the environment of the tank/storage may be allowed to transfer in an enhanced manner into the tank and to increase the temperature of the contents of the tank so that the thermal conductivity of the insulation of the tank is adjusted to be higher. The heat energy available within the tank/storage may be allowed to transfer in an enhanced manner outside the tank and to decrease the temperature of the contents of the tank so that the thermal conductivity of the insulation of the tank is adjusted to be lower.

For example, the durability of perishable goods may be improved. The variation in temperature of material to be stored can be reduced. The gasification and/or evaporation of gasifiable or vaporizable materials, such as fuels or waste, may be decreased or increased according to the application. When decreasing the generation of gases, non-desirable emissions to the environment of the tank can be decreased.

The pressure of a gaseous medium may be increased to increase the thermal conductivity of the insulator, and the pressure of the gas may be decreased to decrease the thermal conductivity of the insulator. Decreasing the pressure of the insulating gas to a level lower than the atmospheric pressure is particularly preferable, as even small pressure differences may enable achieving significant differences in the thermal conductivity of the insulator. Heat may be received from the environment into the insulation volume in an adjustable manner and/or heat may be transferred to the environment outside the insulation volume in an adjustable manner. As an example, an insulation structure with which the contents of a tank or storage is insulated against the influence of cold may be adjusted so that the insulator allows the transfer of outside heat into the contents. Correspondingly, an insulation structure insulating against the influence of heat may be adjusted so that the insulator allows the transfer of the heat of the contents in an enhanced manner outside the tank. Known fixed insulation also prevents the transfer of heat when it would be more sensible not to insulate.

Other advantages will become apparent from the following description and claims.

Various embodiments of the present invention will only be or have only been described in connection with one or some of the aspects of the invention. A person skilled in the art will appreciate that any embodiment of an aspect of the invention may be applied in the same aspect and other aspects alone or in combination with other embodiments.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be described in the following by way of example with reference to the appended schematic drawings, where:

Figure 1 shows a tank in accordance with a preferred embodiment of the invention; and

Figure 2 shows a storage which is partially surrounded by a soil layer;

Figure 3 shows a storage comprising two separate adjustable insulation volumes; and

Figure 4 shows a tank comprising separate adjustable insulation volumes, one of which is arranged in the sphere of influence of the temperature of groundwater.

DETAILED DESCRIPTION

In the following description, like references refer to similar parts. It should be noted that the figures are not to scale in all cases and that they mainly serve the purpose of illustrating embodiments of the invention.

Figure 1 shows a tank 1 , comprising an inner shell 2 and an outer shell 3 fitted outside the inner shell. An inner surface 2' of the inner shell 2 defines a reception volume 4 of the tank 1 for the material to be stored. The inner surface 2' of the inner shell 2 opens in the direction of the material intended to be stored within the tank 1. The material to be stored may be any substance or material, preferably flowing material, such as a gaseous, liquid, semi-solid, pumpable, viscous, powdery or granular material. The material to be stored is not, as such, intended to be limiting for the invention. Figure 1 does not show the opening of the tank for transferring the material between the inside and outside of the tank 1. Figure 1 does also not show connections, e.g., for the material to be stored, measurement means for material amounts, a service door or the like, typically belonging to tanks. Metal and plastic materials have been used as the material of the tank.

In Figure , the space defined by an outer surface of the inner shell and an inner surface of the outer shell is formed as an insulation volume 5, which entirely surrounds the inner shell. More or less of medium has been fitted to be located in the insulation volume 5 through a channel 6. The insulating capacity of the tank 1 is arranged to be adjustable so that the thermal conductivity of the insulation volume 5 can be adjusted.

In Figure 1 , an outer surface 3 of the tank has been arranged within the sphere of influence of the varying temperature of the environment, preferably in the open air.

In the tank 1 , an insulation structure comprises a double shell structured wall 2, 3, which surrounds the material to be stored. The insulation volume 5 having adjustable thermal conductivity is fitted between the shells 2, 3.

In connection with the tank 1 , which is presented as an example of the insulation structure, a vacuum pump 7, suitable for adjusting the pressure of the medium, the density of a medium and the amount of the medium, is arranged as an adjustment means 7 of the thermal conductivity of the insulation volume 5. The operation of the vacuum pump 7 is controlled by means of a control device 8. The communication between the vacuum pump 7 and the control device 8 is indicated by 8'.

Optionally, the internal temperature of the tank 1 may be measured with a first temperature sensor 9, which is preferably located within the inner shell 2 and the measurement information of which is communicated to the control device 8 (dashed line 9'). Optionally, the temperature external to the tank 1 , i.e., the temperature of the environment, may be measured with a second temperature sensor 10, which is preferably located outside the outer shell 3 and the measurement information of which is communicated to the control device 8 (dashed line 10'). The measured temperature values may be processed in the control device 8. In the control device, an adjustment value for controlling the vacuum pump 7 may be determined on the basis of measured temperature values. The control device enables conducting the medium into and out of the insulation volume 5 depending on the temperature of the environment.

The pressure information of the insulation volume 5 is communicated from a pressure sensor 14 located in the insulation volume 5 to the control device 8 (dashed line 14').

The medium may be conducted into and out of the insulation volume 5, depending on the temperature of the environment. When the temperature of the environment is lower than that of the contents of the tank 1 , a gaseous medium may be reduced in the insulation volume 5 to cool the contents. When the temperature of the environment decreases, the gaseous medium may be reduced in the insulation volume 5. When the temperature of the environment is higher than that of the contents of the tank 1 , the gaseous medium may be reduced in the insulation volume 5 to heat the contents. When the temperature of the environment increases, the gaseous medium may be reduced in the insulation volume 5.

The tank 1 comprises an underpressure-tight insulation volume 5 arranged outside the inner shell for a gaseous medium to be pressurized. The medium to be fitted into the insulation volume 5 may be underpressurized in an adjustable manner by means of the vacuum pump 7. To increase the thermal conductivity of the insulation volume 5, the density of the medium fitted into the insulation volume, such as a gas or a gas mixture, can be increased by increasing the pressure on the medium. Comparably, inversely, in order to decrease the thermal conductivity of the insulator, the density of the medium fitted into the insulation volume 5 can be decreased by increasing the pressure on the medium, whereby the thermal conductivity of the medium decreases.

The insulating capacity of the insulation of the tank can be adjusted by changing the pressure of the insulation volume 5. A pressure corresponding to that of the environment can be arranged in the insulation volume. The insulating capacity of the insulation volume 5 may be increased by decreasing the pressure on the medium in the insulation volume. The insulation volume may be underpressurized. The underpressure in the insulation volume may be increased. A vacuum may be formed in the insulation volume.

Preferably, the insulating capacity of the insulation is decreased by increasing the pressure on the medium in the insulation volume. In accordance with some embodiments, an underpressure of the medium in the insulation volume is decreased. The insulation volume may be overpressurized. The overpressure in the insulation volume may be increased.

The thermal conductivity of the insulation volume may be increased by circulating liquid in the insulation volume. What was presented in the general section of this description may be applied to the adjustment of the thermal conductivity of the insulation volume 5 of the tank 1. Figure 2 shows a storage 11 , comprising an inner shell 2 and an outer shell 3 fitted outside the inner shell. An inner surface 2' of the inner shell 2 defines a reception volume 4 of the tank 1 for the material to be stored. The inner surface 2' of the inner shell 2 opens in the direction of a material intended to be stored within the storage 11. As for the tank 1 , the material to be stored may be any substance or material, preferably flowing material, such as gaseous, liquid, pumpable, viscous, powdery or granular material. The material to be stored is not, as such, intended to be limiting for the invention. Figure 2 does not show an opening for transferring the material between the inside and outside of the storage 11.

In figure 2, the space defined by an outer surface of the inner shell and an inner surface of the outer shell between them is formed as an insulation volume 5, which partially surrounds the inner shell 2. The insulation volume 5 is defined by a partition 15, which is fitted in a pressure-tight manner between the inner and the outer shell. The space between the inner shell and the outer shell is partitioned so that the insulation volume 5 having adjustable thermal conductivity is on one side of the partition 15, on the upper side in the case of Figure 2, and on the other side is a department of fixed insulation 13. More or less of medium has been fitted to be located in the insulation volume through a channel 6. The insulating capacity of the tank 1 is arranged to be adjustable so that the thermal conductivity of the insulation volume 5 can be adjusted.

The storage 11 is located partially within ground level 12, surrounded by a soil layer 16. The above-ground part of the storage 11 is equipped with an insulation volume 5 having adjustable thermal conductivity for a medium, fitted outside the inner shell 2. The shell part of the storage 11 below ground level 12, which is not directly within the sphere of influence of the varying temperature of the environment, is equipped with a fixed insulator 13.

A vacuum pump 7 suitable for adjusting the pressure of the medium, the density of the medium and the amount of the medium has been arranged as an adjustment means 7 of the thermal conductivity of the insulation volume 5 in connection with the storage 11 presented as another example of the insulating structure; the operation of the vacuum pump 7 is controlled by a control device 8 as in Figure 1.

The pressure information of the insulation volume 5 is communicated from a pressure sensor 14 to the control device 8 (dashed line 14').

What was presented in the general section of this description and in connection with the description of Figure 1 may be applied to the adjustment of the thermal conductivity of the insulation volume 5 of the storage 11 of Figure 2.

The temperature inside the storage 11 may be measured with a first temperature sensor 9, and the temperature outside the storage, i.e., the temperature of the environment, may be measured with a second temperature sensor 10. The measured temperature values may be processed in the control device 8. In the control device, an adjustment value for controlling the vacuum pump 7 may be determined on the basis of the measured temperature values. The control device enables conducting the medium into and out of the insulation volume 5 depending on the temperature of the environment.

Figure 3 shows a storage 21 , which comprises two insulation volumes 5.1 and 5.2 separated from each other with a partition 15, the thermal conductivity of the insulation volumes 5.1 and 5.2 being adjustable. The storage 21 deviates from the storage 11 of Figure 2 in that the insulation volume 5.2 having adjustable thermal conductivity has been fitted in place of the fixed insulator 13. A first pressure sensor 14.1 is arranged in the first insulation volume 5.1 , from which the pressure information of the insulation volume 5.1 is communicated to a control device 8 (dashed line 14.1 '). A second pressure sensor 14.2 is arranged in the second insulation volume 5.2, from which the pressure information of the insulation volume 5.2 is communicated to the control device 8 (dashed line 14.2').

The control device 8 may control a vacuum pump 7 to separately adjust the first insulation volume 5.1 through a first channel 6.1 and the second insulation volume 5.2 through a second channel 6. 2. As an example of the operation of the storage, heat energy may be conducted to the contents of the storage 21 from the environment above ground level 12 during warm weather, advantageously enhanced by solar radiation (for example, by decreasing the insulating capacity of the insulation volume 5.1), and even coolness may be obtained from the soil layer 16 to cool the contents (for example, by decreasing the insulating capacity of the insulation volume 5.2). As another operational example of the storage, heat energy may be conducted from the contents of the storage 21 to the environment above ground level 12 during cold weather, preferably winter (e.g., by decreasing the insulating capacity of the insulation volume 5.1). Therefore, the temperature of the contents of the storage 21 may be controlled in an energy-efficient manner.

Figure 4 shows a tank 31 comprising three separate adjustable insulation volumes 5.1 , 5.2 and 5.3. The structure having adjustable insulating capacity shown in Figure 4 comprises a cylindrical tank 31 installed in a vertical position. In connection with the first insulation volume 5.1 and second insulation volume 5.2, reference is made to the description of Figure 3. A third insulation volume 5.3 is arranged below the second insulation volume, separated by a second partition 15' and arranged within the sphere of influence of the temperature of groundwater in a groundwater layer 18. The boundary between a soil layer 16 closer to ground level 12 and the groundwater layer 18 is highlighted with a dashed line 17. A third pressure sensor 14.3 is arranged in the insulation volume 5.3, from which the pressure information of the insulation volume 5.3 is communicated (dashed line 14.3') to a control device 8, which is not shown in Figure 4.

The control device 8 may control a vacuum pump 7 to separately adjust the first insulation volume 5.1 through a first channel 6.1 , the second insulation volume 5.2 through a second channel 6.2 and the third insulation volume 5.3 through a third channel 6.3.

By way of example, in some conditions, the temperature may be about +6-+25°C in the above-ground environment of the tank 31 , about +6°C in the soil layer 16 and about +4°C in the groundwater layer 18. The contents stored in the tank may be a milk product. The contents of the tank 31 may be maintained at the temperature of about +6-8°C as follows:

a) when temperature decreases, the contents is heated by means of the insulation volume 5.1 by increasing the thermal conductivity of the insulation volume 5.1

(optionally, the thermal conductivity of the third insulation volume 5.3 is also decreased),

b) the temperature is maintained by means of the second insulation volume 5.2, and

c) when the temperature of the tank contents increases, the contents of the tank is cooled by means of the third insulation volume 5.3 by increasing the thermal conductivity of the insulation volume 5.1 (optionally, the thermal conductivity of the first insulation volume 5.1 is also decreased). A mixing device 19 may be arranged in the reception volume 4 of the tank 31 to mix the contents of the insulation structure and to enhance the heat transfer between the contents and the outside of the tank. The mixing device may comprise a rotatable propeller. Doors of the tank are indicated by reference number 20.

A temperature sensor or sensors may be arranged in connection with the soil layers in figures 3 and 4, which may be used to measure measurement information to be communicated to the control device 8 and to be processed by the control device 8 to generate an operating signal for an adjustment device 7.

At least two insulation volumes arranged to be separate from each other and having separately adjustable thermal conductivity may be arranged in an insulation structure to be modernized. The insulators or some of the insulators of an insulation structure that has been in use (e.g., a tank, storage or container) may be replaced by the insulation volumes presented in this description, arranged to be separate and having separately adjustable thermal conductivity.

As an example of arranging an insulation structure outside the inner shell at least two flexible insulation bags or sleeves may be mentioned, arranged to be separate from each other, having separately adjustable thermal conductivity, arranged outside the insulation structure and shaped in accordance with the shape of the insulation structure. The insulation sleeve or bag has preferably an adjustable insulation volume arranged between two walls. The insulation bag or sleeve may be filled with a medium. The insulation bag or sleeve may be installed around a tank or a container. Insulation bags or sleeves may be installed side by side so that the influence of at least two insulation volumes is directed at significantly different locations of the reception volume of the insulation structure intended for a material to be fitted into the insulation structure.

In accordance with some preferred embodiments, at least two insulation volumes arranged to be separate from each other and having separately adjustable thermal conductivity are arranged in at least two different environments so that significantly different temperatures are directed at the insulation volumes in the different environments. Thereby the temperature of the material to be fitted into the insulation structure can be adjusted between the (extreme) temperatures of said at least two different environments. In this way, the temperature of the material inside the insulation structure may be adjusted even without external energy. The adjustment of the temperature of the material to be stored may be effected very cost-efficiently by utilizing the adjustable thermal conductivities of the insulation volumes located within the sphere of influence of different environments.

The description given above provides non-limiting examples of some embodiments of the invention. It is apparent to persons skilled in the art that the invention is not confined to the details presented above, but that the invention may also be implemented in other equivalent ways.

Some features of the embodiments presented may be utilized without employing other features. The above description must be regarded as an explanatory account describing the principles of the invention and not as limiting the invention. Thus the scope of the invention is only limited by the appended claims.

Claims

1. An insulation structure (1 , 11 , 21 , 31) comprising an inner shell (2) which surrounds a reception volume (4) intended for a material to be fitted into the insulation structure, characterized in that the insulation structure comprises at least two insulation volumes (5, 5.1 , 5.2, 5.3) for a medium separate from each other and having separately adjustable thermal conductivity, which at least two insulation volumes are arranged outside the inner shell (2) so that the influence of the at least two insulation volumes is directed at significantly different locations of the same reception volume (4).

2. An insulation structure as claimed in claim 1 , characterized in that the insulation structure comprises a means for adjusting the thermal conductivity of the insulation volume (7).

3. An insulation structure as claimed in claim 2, characterized in that the means for adjusting the thermal conductivity (7) is selected from the group: a medium pressure adjustment means, a medium density adjustment means, a medium amount adjustment means, a control device for conducting the medium into and/or out of the insulation volume, an adjustment means for adding the medium to the insulation volume and/or reducing the medium in the insulation volume, a pressure measurement means (14), a temperature measurement means (9, 10), an underpressure pump, a vacuum pump, a material transfer pump, a pressure pump, a pressurized gas source, a pressurized gas tank, a charging valve, a drain valve.

4. An insulation structure as claimed in any one of claims 1 to 3, characterized in that the insulation structure comprises a control device (8) for controlling the thermal conductivity adjustment means.

5. An insulation structure as claimed in any one of claims 1 to 4, characterized in that the space formed by an outer surface of the inner shell (2) and an inner surface of an outer shell (3) between them is at least partly formed as an insulation volume.

6. An insulation structure as claimed in any one of claims 1 to 5, characterized in that the insulation structure comprises at least two insulation volumes separate from each other that are controllable separately.

7. An insulation structure as claimed in any one of claims 1 to 6, characterized in that at least one of the following is fitted into the insulation volume (5, 5.1 , 5.2, 5.3) as a medium: a gas, a liquid, a pumpable medium, a viscous medium, air, water, a refrigerator, a constituent of crude oil, a hydrocarbon, and, preferably, the medium is suitable to be exchanged to replace another medium in the insulation volume.

8. An insulation structure as claimed in any one of claims 1 to 7, characterized in that the insulation structure is fitted into a tank and/or a storage.

9. A method for insulating a structure (1 , 11 , 21 , 31 ), the structure comprising an inner shell (2) which surrounds a reception volume (4) intended for a material to be fitted into the insulation structure, characterized in that the method comprises arranging at least two insulation volumes (5, 5.1 , 5.2, 5.3) that are separate from each other outside the inner shell (2) so that the influence of the at least two insulation volumes is directed at significantly different locations of the same reception volume (4) and separately adjusting the thermal conductivities of the at least two insulation volumes (5, 5.1 , 5.2, 5.3).

10. A method as claimed in claim 9, characterized in that the thermal conductivity of the insulation volume is adjusted by changing at least one of the following properties of a medium fitted into the insulation volume: density, pressure, thermal conductivity.

11. A method as claimed in claim 9 or 10, characterized by fitting a gaseous medium into the insulation volume and decreasing the thermal conductivity of the insulation volume by decreasing the pressure in the insulation volume.

12. A method as claimed in any one of claims 9 to 11 , characterized in that an underpressure, preferably a vacuum, is formed in the insulation volume.

13. A method as claimed in claim 9 or 12, characterized by fitting a gaseous medium into the insulation volume and increasing the thermal conductivity of the insulation volume by increasing the pressure in the insulation volume.

14. A method as claimed in any one of claims 9 to 13, characterized in that the method comprises receiving heat from the environment in an adjustable manner inside the insulation volume and/or transferring heat in an adjustable manner to the environment outside the insulation volume.

15. A method as claimed in any one of claims 9 to 14, characterized in that the medium or part of the medium is exchanged to another medium in the insulation volume to adjust the thermal conductivity of the structure.