WO2016129990A1

WO2016129990A1 - Device for covering a container for containing a gas containing and / or a gas producing substance

Info

Publication number: WO2016129990A1
Application number: PCT/NL2015/050096
Authority: WO
Inventors: Andrea DIAN
Original assignee: Van Weleveld Beheer B.V.
Priority date: 2015-02-13
Filing date: 2015-02-13
Publication date: 2016-08-18

Abstract

The invention relates to device for covering a container for containing a gas-comprising and/or gas-producing substance, comprising: - a central support member; - a covering element extending from the central support member; - at least one floating body disposed close to the outer periphery of the covering element and connected thereto, - first hinge means for pivotally connecting the covering element to the central support member such that the covering element is pivotable between a first position, in which the covering element extends substantially parallel to a longitudinal axis of the central support member, and a second position in which the covering element extends substantially transversely of the longitudinal axis of the central support member. The invention further relates to an assembly of a container for containing a gas-comprising and/or gas-producing substance and a device for covering the container. The invention also relates to a method for arranging a device for covering a container for containing a gas-comprising and/or gas-producing substance.

Description

DEVICE FOR COVERING A CONTAINER FOR CONTAINING A GAS- COMPRISING AND/OR GAS-PRODUCING SUBSTANCE

The invention relates to a device for covering a container for containing a gas-comprising and/or gas-producing substance, comprising:

- a central support member;

- a covering element extending from the central support member;

- at least one floating body disposed close to the outer periphery of the covering element and connected thereto.

Similar devices are known per se. The container may for example containmanure or ooze coming from water treatment plants. By means of covering the container emissions of the manure or ooze can be prevented or at least reduced. Alternatively or additionally the gas may be collected and/or stored under the covering device. .

It is an object of the invention to improve the device of the type described in the preamble. For this purpose the device of the type described in the preamble is characterized in that the device comprises first hinge means for pivotally connecting the covering element to the central support member such that the covering element is pivotable between a first position, in which the covering element extends substantially parallel to a longitudinal axis of the central support member, and a second position in which the covering element extends substantially transversely of the longitudinal axis of the central support member.

With use of the first hinge means the covering element can be moved easily between its first and second position, wherein in the first position of the covering element the device can be easily installed in or removed from the container, because the covering element then extends substantially vertical or parallel to a peripheral wall of the container, and wherein in the second position of the cover element, the cover element extends from the central support member to the peripheral wall of the container.

It is noted that the container may have any desired cross-sectional shape, such as substantially round or rectangular. The covering element preferably has a cross-sectional shape that is adapted to the shape of the container, and can for example also be substantially round or rectangular. In the case of a round container and cover element the cover element is in its second position generally radially outwardly from the central carrying from body.

In another embodiment of the device according to the invention the covering element comprises second hinge means connected at a determined distance from the central support member to the covering element, which second hinge means are configured to divide the covering element into two first peripheral parts pivotally displaceable relative to each other such that the two first peripheral parts are displaceable between a first, folded position, in which the inner surfaces thereof extend at an angle greater than 180° relative to each other and in which during use of the device at least one peripheral part of the two peripheral parts extends substantially flat on and parallel to the substance, and a second, str aightened position in which they extend substantially in one plane and in which during use of the device they extend substantially obliquely upward relative to the substance from a peripheral wall of the container to the central support member, and wherein during use of the device the two first peripheral parts are configured to displace from their first position to their second through a gas pressure being exerted.

An advantage of such an embodiment is that by applying a gas pressure of a gas that is present in the substance or is produced by the substance the covering element is able to move upwards from its first, folded position to its second, straightened position. In that position, the covering element extends obliquely upwards relative to the substance level, such that under the covering element a space is defined for containing gas. This gas may, if desired, be sucked out of this space, such that the gas can be recovered and used. In the straightened position of the covering element the two first peripheral parts together reach a maximum length, such that the covering element may extend from the peripheral wall of the container up to the central support member and thereby at least almost completely covers the container.

It is noted that, because in its second position the covering element extends substantially obliquely with respect to the substance level, precipitation falling thereon is easily guided obliquely downwards to the circumferential wall of the container. If desired, this precipitate can be collected or directed to the substance.

It is further noted, that the peripheral part that extends on the substance may in particular be the outer peripheral part that is closest to the circumferential wall of the container.

Preferably the second hinge means are disposed on a side of the covering element remote from the substance during use of the device.

As a result thereof the second hinge means will not come into contact with the substance and will not become contaminated by this substance.

In another embodiment of the device according to the invention the at least one floating body extends over substantially the whole outer periphery of the covering element and is configured to extend, in the second position of the two first peripheral parts, between the peripheral wall of the container and the covering element duringuse of the device.

An advantage of this embodiment is that the floating body is able to at least substantially seal the optional gap between the covering element and the circumferential wall of the container. The floating body has a substantially annular shape.

In another embodiment of the device according to the invention the covering element comprises third hinge means connected at a determined distance from the central support member to the covering element, which third hinge means are configured to divide the covering element into two second peripheral parts pivotally displaceable relative to each other such that the two second peripheral parts are displaceable between a first folded position, in which they extend substantially parallel to each other, and a second straightened position in which they extend substantially in one plane, which third hinge means comprise connecting means for connecting the third hinge means to lifting means for raising the device, wherein in a raised position of the device the two second peripheral parts are configured to be located in their first position.

With use of the connecting means, the third hinge means can be connected to the lifting means. When the covering element is lifted by the third hinge means the two second peripheral parts may, preferably automatically, move into their first position. In this position the covering element occupies relatively little space, because the two second peripheral parts extend substantially parallel and overlapping to each other, and as such the device can be lifted in and out of the container in a simple manner. Because the device also comprises said first hinge means, the parallel extending second peripheral parts extend substantially parallel to the longitudinal axis of the central support member in their first position, or, in other words, in use substantially vertical.. When the device is lifted into the container and is arranged onto the substance, the two second peripheral parts may move, preferably automatically, into their second position as a result of the buoyance of the at least one floating body.

It is noted that, when the device comprises both the second and the third hinge means, the covering element comprises in total substantially three peripheral parts.

In another embodiment of the device according to the invention the third hinge means comprise locking means for locking the two second peripheral parts in the second position.

In another embodiment of the device according to the invention the second hinge means are disposed between the third hinge means and the central support member.

In another embodiment of the device according to the invention the central support mem- ber takes a buoyant form.

In another embodiment of the device according to the invention the covering element takes a flexible form.

In another embodiment of the device according to the invention the covering element comprises a number of ribs extending from the central support member and connected to the covering element, wherein:

- the first hinge means are connected to the ribs;

- optionally the second hinge means are connected to the ribs, and

- optionally the third hinge means are connected to the ribs.

In another embodiment of the device according to the invention the device comprises con- necting means for connecting gas outlet means for discharging gas during use of the device from a space defined between the covering element and the substance. In another embodiment of the device according to the invention the device comprises an opening with a closing element, which closing element is displaceable between a first position, in which the closing element leaves the opening clear, and a second position in which the closing element closes the opening, which closing element comprises floating means such that the closing element is configured during use of the device to float on the substance and due to its buoyancy is configured to be situated in its first position in the first position of the two peripheral parts and to be situated in its second position in the second position of the two peripheral parts.

It should be noted, that the first, second, and third hinge means only have been called so to indicate the difference between them. The device can for example also only comprises the first and third hinge means and no so-called second hinge means. It is further noted that the first peripheral parts and second peripheral parts only have been called so to indicate the difference between them. The device could for example also comprises only the second peripheral parts and no so called first peripheral parts.

The invention also relates to an assembly of a container for containing a gas-comprising and/or gas-producing substance and a device for covering the container as claimed in any of the claims 1-12, wherein the container comprises a bottom and a peripheral wall extending upward from the bottom, wherein the device is disposed in the container and the covering element extends in its second position from the central support member to the peripheral wall of the container.

The invention further relates to a method for arranging a device for covering a container for containing a gas-comprising and/or gas-producing substance as claimed in any of the claims 1- 12, comprising the steps of:

(a) lifting the device into the container in the first position of the covering element, and subsequently

(b) displacing the covering element to its second position.

Hereafter, further aspects, embodiments and advantages of the device according to the invention will be described. The device may comprise any of the aspects and embodiments described below, and in any combination.

The invention provides in the possibility to win at low temperature fermentation usable gases and at the same time reduce for example nitrogen emissions. Herewith the loss of heat can be reduced by applying for example insulating covering material or install two or more covering layers.

In the state of the art are a variety of seals described, including floating covers, whereby also harsh but generally materials of construction materials are used with a flexible textile structure which gas closing properties are created by means of single or multiple layers thermoplastic coatings. These lightweight, often self-floating materials are strained, whether or not reinforced with belts fastened to the container walls possibly supported by a central column. Known examples of floating seals with flexible materials are shaped by means of, inter alia, surrounded with foam and / or air-filled tubes. Wherein these also function as a floating body and fix the shape of the cover.

The floating cover submitted in this application for patent distinguishes itself by a pressure-controlled deformability of the device in its entirety, wherein hinged ribs extend from a central floating body up to the container wall. Due to the dimensioning of the ribs, the device can be modeled for most common container shapes. Essential is that larger deformities, as there are egg-shaped containers, can be absorbed through corresponding rib length differences and less frequent seen abnormalities or container wall profiles such as corrugated sheet steel containers by means of the flexibility of a surrounding floating body. The buoyancy and weight of the device can be adjusted with two types of floating bodies. A central support member filled up with for example aerated concrete and a type for example made of fiber-reinforced foil. Whereby this latter type may be applied at the bottom side of the floating cover as compartments between the ends of the ribs. And the surrounding drop-shaped flexible floating body with the round side facing the container wall, may be divided into compartments. The compartments below the device at the end of the ribs and the surrounding floating body have in common that they are substantially filled with a liquid combined with anything floating. The outer ring is formed by a flexible foil of for example sliced strips of which the long sides are connected to the layers at the wide end of the outer peripheral part creating a stiffly border. The surrounding floating body will get pinched at an intermediate container and the liquid seal due to methane formation excessive gas pressure between the surrounding reinforced stiffly edge of the device and the container wall. The filling consists of for example an environmentally-safe anti-freeze liquid and cubes of foam material with a preferably closed cell structure. Another example of this floating filler is hollow plastic spheres. The fill fluid has such a chosen volume that, at straightening of the ribs it accumulates on the underside between the substance and covering element. The floating foam cubes for example neoprene foam rubber weighing for example 50 kg / m³ accumulate especially in the ring on top of the liquid applied in part higher than the driving level of the covering element. Here, the outer surrounding floating body gets kidney shaped and forms a flat side at the container wall. And thus, a substantially gas- tight seal between the device and container wall is realized. This construction results in a drastically improved seal against unwanted emissions compared to well-known gas-filled outer rings. In particular, for containers filled with substances with a higher dry matter. The construction is also suitable for the use in containers with pipes and / or with mixer columns on the inner walls. By means of a bow-construction pointing towards the central support member and a uniform third outer floating body enclosing the turning circle of a for example wall-disposed mixer which is left out from the periphery circle of the device provides in a minimum contact surface of the substance with the outside air and it is prevented that the gas pressure and with the aid thereof mediated working position of the device get lost.

The device can be stabilized in its position by means of from the container top placed flexible tightrope connected to for example an at the container bottom disposed fixation and a guide eye with a guide tube through the covering element disposed on one of the ribs tips. In case of a filled up container it may be sufficient to descend for this purpose a weight configured with mounting eye to be placed along the container wall. But which preferably at the next vacancy gets replaced by an eye disposed in the container bottom.

Application of covers on containers is in general in order to meet regulations with respect to emissions of among others methane gas and ammonia. As for reasons of odor reduction and in order to avoid mixing of the container contents with rainwater. The latter entails transport advantages when spreading the manure or digestate container contents. The floating covers are usually built without center column and may therefore also without the need to empty the container be lifted in the container. Floating covers meet with German regulations because of their low gas content, the so called "Storfallverordnung" dictating restrictions to the maximum volume of gas storage at for example biogas plants.

A floating cover does not have any static effect for the construction of the container. This has a cost advantage for the calculation and is because of this result in favor of the floating cover in comparison to wall-disposed covers. Containers constructed with a bottom too thin for placing a middle column or thin- walled metal containers can be durable closed with floating covers.

Because, in comparison with the standard "tensile structure-type" cover by what is meant the on the container edge tensioned mostly combined with middle column flexible roofs, the floating covers are not disposed under permanent tension, and the gas pressure and wind forces are in case of this invention compensated by the weight and flexibility of the floating bodies and / or the pivoting action of the ribs the mostly in the flexible covering material processed fibers or yarns are under less elongation stress, which also affects the structure of the mostly thermoplastic coatings and thus reduces the life expectancy of the tensile structure covers. The lifetime expectation of a floating cover is for this reason at equivalent material use longer.

In Germany are about 7000 biogas installations that have to meet with the so called "Storfallverordnung" regulation. At the same time the surveillance on the minimal covered retention time is increased. Tensile structured covers with middle column have because the variable distance between substance and cover an equivalent gas volume. Generally in Germany currently operating biogas plants do not meet with the mandatory number of days of closed fermentation. These circumstances result in a significant market potential for floating covers, this in addition to the applications of sludge's filled containers of water treatment plants and agricultural companies. Wherein the application of the invention as described above is thought to the latter and for existing agricultural containers.

The device is intended primarily as a beginning for further processing of whether or not separated manure or digestate taking into account both environmental guidelines and financial feasibility.

Known rigid floating covers require for installation on a filled-up container a building site next to the container of at least the container dimensions. In practice this is during build-up and certainly during maintenance or dismantling a limiting factor. In addition, weather conditions for assembly, disassembly and emergency interventions especially for the large diameters are due to the wind catching surface problematic. The invention with hinged ribs distinguishes itself in the construction, maintenance, use and dismantling in this with significant benefits. The device can be assembled at an appropriate nearby or even at a larger distance located field and then folded similar to the Knirps folding umbrella. Unfolding during assembly can manually for example by means of drawstrings and a team of technicians.

With the help of the mounting rings (2C1) and possibly for this purpose elsewhere on the ribs disposed rings, combined with a system of assembled tubes connected to a crane a mechanical mounting and demounting can also be realized. A winch placed in a ring of tubes could descend or ascend the floating body according to the wishes to kink the cover in or out.

In addition, the hinge mechanism of the invention also provides in the gastight connec- tion of the device to the container wall.

By means of the weight of the for example aerated concrete filled central floating body the device can also be assembled even in windy conditions or transported to the container to cover it to be lifted after which it can be hoisted into it. Only after the folding-in the container, the compartments and the outer ring are filled with liquid. The self-floating filling element can con- tribute to a safe durable floating product. In several countries within the EU and in particular in Switzerland, agricultural enterprises are supported with grants on investments for covers. A cover as this application describes which can also be folded easily when disassembling are easier eligible for leasing in comparison to stationary products. Known floating covers also face unstable positioning in case of wind and associated vacuum forces. By means of respecting the local weather conditions and adjustment of the device weights in the central support member, the compartments and the surrounding floating body a stable positioning and an improved wind stability can be obtained. Sizing of the central support member the compartments and surrounding floating body can be determent by container diameter and by the local weather conditions. In case of heavy snow the device can be settled down in the resting position by means of depressurizing the space between substance and covering element. The surface of the covering element that is fixed tide on the long ribs of the device settles down and is carried in this position by the substance. In a straightened state, these and the shorter to the central floating body-disposed ribs are carried by gas pressure between the fluid container and the closing parts. For what reason these ribs are intended to ensure the rigidity of closing more than wearing of the structure. The working pressure of the device is to adjusted to a straight line of the ribs in the straightened position. Through winning the emission gases and apply it for example as fuel for vehicles, heating or cooling for example in staples, raising the container input temperature through remaining heat and / or production of electricity the device becomes an investment with the prospect of earnings. By application of the device in agricultural companies in for example low temperature fermentation at for example 20°C and a retention time of for example 120 days reduces emissions and in what manner also a huge source of energy is opened-up. If application of the emission gases is not desired these gasses can also be flared off whereby unlike various known container covers or lack thereof for example methane eventually ends up in the environment.

Furthermore, the Invention seeks to provide for easy installation in such a way that the higher material cost is more than compensated.

At least one of these and / or other objects are achieved with a foil cover of linked parts

1A nailed with ribs, a central support member 2D, a surrounding flexible floating body ID filled up with a liquid and a floating element. Possible between the rib tips on the substance side additional configured with compartments 2Y which are likewise filled with a composition of liquid with small and / or larger pieces of floating material. Wherein the ribs for example are formed out of three or eventually more by means of hinge linked parts. The first shortest parts 21 connected to the central support member 2D are for example U-shaped profiles made for example out of fiber reinforces plastic or hardwood eventually combined with plastic profiles are connected hanging down in resting position and connected to the first hinge according FIG. 2A which ribs on the opposite end are attached to the second hinge Fig. 2B in resting position reaching the container sub- stance. The other for example two longer ribs 2E and 2F lie after installation at rest parallel to the surface of the substance, among others kept floating by means of the outer flexible surrounding body according FIG. 3A made of for example a polyurethane foil and possibly by the compartments 2Y between the rib tips at substance side.

The possible to place central lid 1H (figure 3) connected to a central dome IF directly with the parts 1 A connected or eventual by means of a collar 1 Al form, together with the surrounding floating body a closed floating cover which is straightened on the construction of ribs in resting position preventing that a majority of the gases come out of the container substance and escape into the outside air. The collar 1A1 can be prohibited to get squeezed between the rib tips of 21 and 2E during stretching of the ribs, for example by means of the rubber strip 2B2. The above -described structure comprises long ribs which are connected by preferably corrosion-resistant and at the air side of the covering element disposed hinges. Wherein this covering element disposed between ribs and hinges secures the gas tidiness of the floating device. Together with the shorter, at the central floating body connected for example U-shaped rib and in such a way chosen opposing accordion resembling hinges achieves that the to the ribs attached covering element can fold, unfold or is able to remodel. The hinges can eventual be made off with each other connected uniform shaped profiles in accordance with the appended figures.

After assembly and descend the device into the container and after unfolding of the ribs into the second position the hinges between ribs 21 and 2E get unlocked and the hinges between ribs 2E and 2F get locked for example by means of stainless steel telescoped tubes, rings, nuts and bolts as shown in figure 2A. The composition and dimensions of this connecting material 2Q is selected so that abrasion and sliding for example plastic is avoided and that the hinges can move freely. In case of folding up of the ribs into the first position, as done for example with the purpose to clean the container in stage of emptiness or demounting of the device for other reasons, the hinges have to be adapted in the reverse, thus hinge according figure 2C gets unlocked and hinge according figure 2B is locked.

Hatch or hatches 5B, the cover 5E with floating body 5G including the reinforcement plate, the attached bow 5H have preferably to be removed and also the inflexible, on ribs disposed gas pipe has to be removed before the ribs can be folded into the first position.

The outer ribs 2F can at the opposite end of where according to figure 2B the hinges are attached and reach there close to the container wall be configured with a curved shaped and such dimensioned extension 2G that the end thereof, in a straightened position of the ribs pass by underneath the outer floating body ID and touch the container wall IN. The to the central floating body by means of hinges connected first short ribs 21 made of for example out fiber of reinforced plastic or for example out of hard wood is eventual combined with a plastic U-shaped profile that covers a to the central floating body connected eye or preferable in another embodiment of the device tooled partly rounded delta-shaped plates 2T that are connected to the construction of the central floating body. These plates are shaped in such manner and disposed that the U-shaped ribs in the resting position are not hanging parallel with the rods 2K of the central floating body and / or not perpendicular with the container substance. The angle of the to the central floating body disposed ribs is in such way that in case of accumulating gas pressure the entire construction of ribs and covering element will lift from the container substance and in which circumstances the ribs stretch that far that the surrounding floating body and / or the curved shaped extension 2G touches the container wall. The enclosing of the delta-shaped plate 2T by the U-shaped profile according figure 2A contributes to a stabilized situation of the central floating body in resting position of the floating device. The delta-shaped plate is modeled in such way that in the event of over-filling of the container the ribs 2E and 2F can lift by means of the hinge according figure 2A that far that the substrate can flow over the upper edge of the container. It should be noted that the height of rise of the central floating body is possibly limited for example by means of crosswise tensioned belts disposed on the upper edge of the container of IN or is limited by means of cables as illustr ated in figure 6/6D. The central floating body 2D is filled up with for example aerated concrete of which the specific gravity provides a desired volume of the floating body underneath the substrate surface and the volume above.

This weight contributes, together with the weights of compartments 2Y and surrounding floating body ID to a combination of buoyancy and weight. Weight that is desired to be able to build up pressure wherein the stability of the positioning is ensured and the shape of the surrounding floating body ID joins the container's interior. The aerated concrete is poured into for example a cylindrical foil-bag which is surrounded by a for example flexible plastic plate 2L that is bended into a cylinder at the inside of gets connected to the rods 2K that for example could be made of recycled plastics provided with substantially entailing above the container substance issuing delta-shaped plates. The rods 2K are at both ends fixed to the double ring set 2J that for example are made of plastic or hard wood. These sets of rings could also be made out of stainless steel or a hybrid implementation of plastic and stainless steel.

To realize a stable position of a in such way constructed central floating body the bottom of the fluid dense foil-bag can be filled up with for example have an additional layer 2N with a higher density then aerated concrete, as for example normal concrete that has a density of 2400 kg/m³. In the aerated concrete on the central upper side a space 20 is recessed, for example sealed by means of a reservoir made of plastic material that can be closed tide with for example a screw lid. This is done to create the possibility for adjustment of the operating level by means of weights after placement of the device in resting position. Namely in such a way that the rib 21 disposed to the central floating body at its opposite end, where the hinge according figure 2B is disposed reaches to the surface of the container content. With the result that the at the hinge according figure 2B attached to the middle horizontal rib 2E and hinge according figure 2C with the thereto disposed rib 2F are parallel to the surface of the container contents. The intended properties of the central floating body can be realized in other shapes and with various other materials.

The for example flexible foil cover is tensioned over the long fixed ribs 2E and 2F whereby the distance between these ribs in straightened second position of the device can be limited by means of belts 1C which are disposed on and / or under the covering element. The device can, in addition to the closed surface of connected parts 1A around the central floating body get sealed gas-tight by a dome-shaped also made of for example foil construction IF that covers the central floating body totally. This dome can be configured with a removable gas-tight cover or lid. Such lid 1H then provides access to the central floating body in order for example to do maintenance at possible installed equipment as for example a liquid pump, and to the hinges according figure 2A or the rings that are connected to the central floating body for lifting operations.

The totality of the device with floating bodies ribs and foil construction placed on for example a manure holding container realizes in its resting position that a larger portion of the released gases is retained to escape into open air. This, with exception of the open so dimensioned gap between the surrounding floating body and the inner wall of container IN what allows that the device can descend during emptying of the container freely from the inner wall.

The accumulating gases cause that the foil of for example 800 gram per square meter together with ribs at a pressure from about 0,1 mbar or 1 kg of pressure force per square meter, is lifted of from the container contents. Due to the hinges between the ribs on the central floating body and the locked ribs swerve them in a straightened position until the hinges according figures 2A and 2B are fully straightened and the surrounding floating body and / or the curved extension 2G eventually disposed to the outer ribs touches the inner container wall. Wherein the end of the rib or the extension part move by means of the gas pressure because of the diagonal line length, created by the ribs, between this outer end and the hinge according figure 2A with rib 21 disposed to the central floating body and the sum of its length and the lengths of the horizontal on the container substance resting ribs this end is reaching towards the inner container wall. These lengths of the ribs and segments 1A will have to be dimensioned so that they fit with the container dimensions its shape and eventual shape abnormalities.

During the stretching of the ribs the device forms a calculated angle between the hinge according figure 2A and the tip of the outer ribs 2F. Because of this angle rainwater will get collected between the outer end of the covering element and its surrounding floating body ID that is reaching out of the container substance. For this purpose on points 1J this water can be removed, if desired with the aid of an suction system and optionally be stored before later use. The free space formed by the angle between the device and the container substance can serve by using the space 20 inside the central floating body 2D by installing for example a liquid pump. This to suck up liquid from the container bottom and to spray this over the eventual floating layer of for example manure. Such system could replace a conventional propeller mixer. Whereby the sucking level can be chosen depending on weather there is a sediment or floating material.

The angle of the ribs relative to the container wall also contributes to sliding up of the device in its entirety with the usually daily rising fill level of the container. For emptying the container, the device can be set in the resting position by means of venting the gas pressure. This emptying of containers is usually done periodically according to the applicable regulations.

The stretching of the ribs is limited by means of the hinge construction according the figures 2A and 2B and / or the curved extension piece disposed to rib 2F and the in between available rib lengths. The lifting of the device out of the container liquid and / or the bending of the device in its total can be maximized by means of a pressure regulated gas pump and may be secured with a pressure relief valve. The set maximum pressure is higher than the weight in accordance with the covering element and ribs counted together but smaller than the pressure in which the angle of the ribs increase and / or curve in such way and the central floating body insofar is raised that the surrounding floating body ID and / or the curved extension 2G detach themselves from the container wall. The weight of the above container substance lifted mass will be regulated within the tolerances compensating the pressure fluctuations and external influences. With the result these influences have no effect on the stability of the positioning. Without pressure control the pressure can reach under given conditions 10 mbar or more under which conditions the device could lift itself from the container substance and the construction is put under unwanted tensions. The pressure relief valve may be part of the gas extraction system and / or redundantly placed elsewhere on the device. Such pressure relief valve may consist of a mechanical exhaust valve with 2V and 2W with a corresponding weight. An electronic pressure sensor may provide by means of an electrical signal in an automated control system of for example a gas pump that is connected outside the container.

Furthermore, the invention provides for the possibility of a service opening according figure 5 that can provide access to the container substance. The container substance usually has the property to winnow in floating components 6E and / or sediment 6F and liquid with dissolved constituents. This is the reason why the substance for example by external mixers become homogenized before going on to transport and / or to be spread on the fields. The invention provides a self-opening service opening by reaching the described resting position of the device. To this end, a floating body according figure 5 is placed on the covering element filled up with for example hard foam and foil overwrought beams 5A bearing disposed hinges and hatches 5B made of van for example stainless steel whose dimensions are chosen so that these shutters are not able to open by the pressure prevailing underneath the floating device. A skirt made of for example flexible foil with preferably a dismountable plastic frame 51 that is attached to the underside of beams 5A of the service opening must assure that the underneath de device accumulating gases are prevented to escape into open air through the shutters that are opened in the resting position what would hinder the erection of the device into the straightened position. The floating body 5J equalizes the higher weight of the service opening with respect to the total weight of for example parts 1 A and ribs. Result of which the angle of inclination of the device is ensured. Whereby the frame is shaped so that the skirt and floating bodies seal the space between the device and container contents completely.

This part of the invention provides furthermore in a floating body 5G that in the second straightened position of the device hangs down connected to a for example stainless steel rings 5F and F51 , connected to plate 5E connected to the beams 5A together forming a compartment 5D that is connected to a segment Alby means of closing, what segments eventually are reinforces with belts 1C. Wherein the floating body 5G is positioned in the straightened position in compartment 5D hanging at one side down towards the container substance. At this lower side of the floating body 5G a curved bow 5H of corrosion-resistant material is installed. This bow pushes at stage of decreasing pressure, thereby descending construction of ribs and covering element, from underneath against the hatches 5B of the service make opening them open by its own weight and associated tension of and on the possible by means of belts 1C reinforces segments 1A. Through this opening a mixer-arm can reach the container substance without manual handling or setting food on the device. What in case of other known floating covers can cause objectionable working circumstances and for what reason such covers are less suitable for frequent mix treatments of the substance. By this mechanism, the invention distinguishes itself from any of the known floating cover.

The rigidity of ribs their mutual connection by the belts and the skirt with frame and floaters prevents the device against turbulence of the container substance during mixing through the service opening in its resting position. Due to the construction of skirt with frame 51 configured with floaters 5J the beams 5A hatches 5B and plate 5E creates a space separated from the pressure that prevails between container substance and the device. The service opening can by reason of a possible escalating pressure and potentially causal damage to the above-mentioned construction be configured with its own pressure control valve 5K.

Positioning of the service opening close to the central floating body provides in the biggest distance between the covering element and the container substance but at the same time the smallest available space between the ribs. As the service opening is positioned closer to the surrounding floating body the obverse applies. The dimensions of the opening, in particular the compartment 5D with the therein inserted floating body 5G can be adapted to the available widths and heights.

The size and shape of the device can be adjusted by equal or unequal lengths of ribs. This allows round, square, rectangular and oval containers and optionally to be sealed and in case of exceptional dimensions by pairwise placement. The containers with exceptional shapes as there are with chamfered corner can be sealed by giving the outer contour of the device a modified form with the aid of stiffeners IE placed on the foil in sealed holders which are pressed in their turn by the tension of the foil on the sealed belts 1C and the covenants and hence co rigid closing layers. Whereby the shape is determined by pressure below the device and the wall IN. The stiffeners are optionally adjustable in length. And can be set at assembly to the desired length, or when necessary, be post tensioned.

Preferably, the ribs 2E and 2F have unequal lengths wherein 2E is longer than 2F. This is in the first instance for reasons of the device can get fold up easier when placed in the container but also for cleaning of the container bottom. Sediment such as sand and stone has to be removed periodically. To this end, the central floating body provides with a partially or entirely flat bottom in a stable standing position on the container bottom after being emptied. Thereby are the surrounding floating body and compartments in whole or in part release of the fill fluids. By means of tensioning cables through the rings 2C1 disposed on the hinge according figure 2C and 2B1 according hinge of figure 2B and the blocked stage of hinge 2B by means of a locking pin in the for this purpose provided openings 2B3 and then folding the ribs from for example the container edge the container bottom is assessable in open air for cleaning without removing the device out of the container. Also, to realize the erection of the device for example in case of cleaning the container floor, a mechanized system of tubes and a pulley could be used for lifting. Regarding dangers at work such as occurring gas poisoning are with this invention the conditions easier and above all safer in comparison to any other known container cover.

The invention will now be explained in more detail with reference to embodiments that are shown in the drawing. In the drawings shows:

Figure 1 a schematic perspective view of the device illustrated in a transverse cross-section of a round container with gas outlet system.

Figure 2 a schematic cross-section of the side left symmetric of the device in resting position and the central floating body.

Figure 2A a perspective detail view of the hinge and connection point of rib 21 at a delta- shaped plate 2T illustrating the connecting screws, bolts, pipes and rings 2Q.

Figure 2B. a perspective detail view of the hinge and connection point of rib 21 with rib

2E.

Figure 2C. a detail view of the hinge and connection point of rib 2E with rib 2F.

Figure 3. a schematic cross-section of the symmetric left side of the device in straightened position of the ribs and the central floating body.

Figure 3 A. a schematic cross-section of the outer surrounding floating body ID and compartment 2Y in straightened position of the ribs.

Figure 4. a schematic cross-sectional of the device in raised position of the ribs.

Figure 5. a perspective detail view of a self -opening service opening.

Figure 5A. a schematic cross-section of a self-opening service opening.

Figure 6. a schematic cross-sectional of the device with dome with in the central floating body disposed liquid pump, hose and nozzles.

Figure 7. a schematic perspective view of the device illustrated in a cross-section of a round container with dome and central hatch. In figure 1 the device is shown in a schematic perspective view with straightened ribs. Presented in a simple embodiment, in a cross-section of a round container IN. The covering element is composed of gas-tight pie-shaped for example out of fibre reinforced foil cut segments 1 A whose cutting seams 1AA and 1AB are interconnected for example by means of closing, in such a way that the parts together with the surrounding floating body ID such as the example of figure 1 a round on the size of container IN attuned closed surface is formed.

By cutting uneven chosen lengths 1AA and 1AB enables to create for example rectangular shaped floating devices or covers for other models of containers. The segments 1A can eventually be configured with belts 1C made out of for example woven or braided synthetic yarns made preferable out of fibres with low stretch rates eventually finished with a thermoplastic coating or impregnation. These belts are one or two sides attached to the segment 1A and welded for example perpendicular to the fold line that results when the usually straight-cut lines 1 AA and 1 AB are laid on each other. Positioning of the belts is for example at the ends of the ribs 2F in order to maximize the distance between these ribs and stability of the frame in its entirety. The belt lengths are in accordance with the distance between the cutting lines 1 AA and 1AB so that at straightened position of the device the ribs keep a controlled distance and de segments 1 A form a reinforced straightened flat surface. The belts are also possible, provided close to the hinges according figures 2A, 2B and 2C and the self-opening hatch II. Or to strengthen the device at desired points as for example near to a mixer notch. At attaching the covering element on the frame of ribs 2E and 2F the belt ends arc coincident with the cutting lines 1AA and 1AB the most stable point of the device in order to absorb the forces that are caused by pressure differences and effects of the weather. For reasons of the different use conditions it is necessary for each production to prepare a static analysis in which materials and processing, such as the number of belts that have to be adjusted and to meet with local weather and /or regulations. The in such way formed spider web-like structure in its entirety is surrounded by the teardrop-shaped flexible and watertight finished floating body ID that in figure 3A has been elaborated and will be described. This together with the compartments 2Y at the container substance side near the rib ends and the surrounding floating body ID. Between this surrounding floating body ID and the belts that connect the ends of the ribs 2F my consist of for example plastic manufactured stiffeners IE. The ribs and stiffeners form together with the joined layers, and as a result thereof partly rigid, of flexible covering material the outer contour of the floating cover and thus determine the range of the surrounding floating body ID designed to get pushed against the container inner wall during extension of the ribs. But also to effect the retraction of floating body ID if the device returns in to resting position.

Between the ribs it is possible on one or more places to mount a self-opening service opening II in order to reach the container substance. To achieve this opening-up, use is made of the stretching movements of the ribs and is specified in detail in Figure 5. At the surface of the device is furthermore visible a pit 1J provided to place a submersible pump for drainage of rainwater also visible at top side is the gas extraction joint and the gas extraction outlet pipe IK. The at stretching of the ribs realized slope effects that rainwater is drained towards the surrounding floating body ID. From the deepest point of the surface 1J the rain water should be pumped out.

After positioning of the device in the container one or more external gas drain pipes IK can be connected, to realize fixation for example supported by the ribs. The inclined position of the device causes not only rainwater to flow off across the covering element but also that condensation in the gas pipeline between the upper connection point 1F1 for example with dome IF and the connection point with the vertical part of the gas pipeline IK is flowing in the direction of the container wall. In the simplified embodiment of Figure 1 with a for the different positions of the device shaped skittle by connected ends Al has connection 1F1 a distance to the container substance in accordance with a connection 1F1 with dome IF. This distance to the central floating body and the inclining position of the ribs and the above the skittle is in such a construction, the danger of clogging by formation of foam considerably smaller in comparison to floating covers in which these and consequently the gas joints have contact with the surface of the container substance. A flexible vertical gas line can be connected to the gas line parallel to the ribs. The horizontal line can thereby using spacers pass over at a so desired height of the covering element that this connection point on a vertical flexible along the container inner wall carrying gas pipe stands at such a height that the associated for example flexible condensate drain not get clogged or only in exceptional cases with foam. It is to note that the current along the inner, vertical section of the gas outlet pipe has a direct condensate outlet connection through the floating device.

The vertical for example coil wire containing flexible gas outlet pipe can move up and down over the container edge by means of a roller system 1M. For reasons of the created more length by this movement outside along the container may a piping system 1L be placed which also serves as an anti-lock water drain. The flexible gas pipe can be connected by means of cable ties and weights lLb. And this for example in mice staircase alignment of the hollow tubes may lay down. Wherein the weights that are preferably positioned in the tubes ILA let the pipeline go down in a gutter. Wherein in each driving level of the device the gas pipe on the container outer side obtains a continuous descending line. The container wall height and thereby to compensate height differences of the device determine the number of parts ILa and / or the distance between them. The end of the flexible gas tube is connected to for example a firm gas pipe that goes underground and there is connected to for example a condensate outlet pit.

Figure 2 shows a schematic cross-section of the left side symmetric of the device and the central floating body with ribs in resting position. Detail drawings 2A, 2B and 2C of the hinging parts are added thereto. In this drawing figure 2A shows the said first hinge means, figure 2B the said second hinge means, and figure 2C the said third hinge means. Located central in the container is a cylindrical floating body 2D that is filled with for example aerated concrete 2X with a specific gravity of for example -700 kg/m³. Because of this specific gravity such floating body is able to carry -300 kg/m³ per cubic meter of supplanted container substance. Unencumbered a aerated concrete filled floating body float approximately 2/3 below and 1/3 above the substance surface level. The cylindrical shaped floating body has been manufactured with for example two layers of stainless steel or plastic curved segments that are linked with bolds forming a closed rings 2J. The two by for example by bolt connected rings can be connected to each other with for example there in-between eight evenly distributed possibly made out of plastic or hard wood rods 2K. A flexible plastic sheet 2L fixed between the ring-sets 2J is closing-of the rods 2K at the inside. Plate 2M closes possibly reinforced with beams the cylinder bottom, causing the thus formed hollow cylinder only remains open at the upper side. This space can be filled up liquid-tight with for example a foil made flexible cylinder shaped bag 2Z that fits tide at the sidewall 2L and bottom 2M. This bottom can, for the sake of driving stability be configured an additional ballast 2N. This ballast can be of normal concrete with a density of - 2400 kg / m³. The weight of the ballast 2N together with that of the other used materials as there are the rings 2J is compensated by the cutout 20 in the aerated concrete 2X and that is closed tide for liquids by for example a bucket-shaped closing 2P. This space can be used as desired, to lower the positioning of the device by means of weights so far that for example the ribs 2E and 2F in resting position of the device lay down horizontal with the surface of the container content. A protective closing of the filling material of the central floating body can be achieved with a water tide resin and lid 2S. The remaining raw materials have been selected for being resistant to the container contents. Each of the rods might have a delta-shaped plate 2T that can be disposed on that part of the rod that reaches out above the container substance, and in such positioning that the sharpest edge stands at equal level with or above the upper ring set 2J of the floating body. The angle of this sharp edge is specific and connected by a hinge according figure 2A with the U-shaped rib 21 with thereto by means of hinge according figure 2B for example T-shaped rib 2E and by means of blocking hinge, that can be realized with for example two T-shaped profiles 2C2 and a U-shaped profile 2C3 bridge-part according figure 2C connected to an also for example T-shaped rib 2F possibly provided with an extension 2G at its opposite end. With a construction as this of for example a set of 8 ribs assembled with a flexible covering element that in conjunction with all ribs will lift at increasing pressure between the container substance and this cover as shown in Figure 6. To achieve adjustment of the desired working height of the device it is possible to provide mounting positions at the rods at various heights for the delta-shaped plates. The profiles can be reinforced with stainless steel strips or be rounded at those places where material may accumulate from the container substance. Closing valve 2V is connected to a pipe 2W with a hinge that is disposed on the flexible covering element being in open communication with the container substance. Because of the weight of the valve is the pressure tolerant set above the working pressure.

Figure 3. shows a schematic cross-section of the left symmetric side of the device in the second straightened position of the ribs and the central floating body. The at the central floating body 2D disposed delta-shaped plate 2T by means of hinge of figure 2A and attached rib 21 stands in a straight inclined position wherein by means of the hinge in figure 2B with the associated rib 2E which is attached to the at the opposite end locked hinge of figure 2C and associated rib 2F have reached a similar inclined position whereby the surrounding floating body located between the ridged multiple layer frame 3 AC and connected elements 1 A and the container wall squeezes and it eventually placed extension 2G touches the container wall IN. The aggregate weight of essentially the fill liquid substance in the compartments 2Y and the weight of the central floating body 2D compensate the pressure built up under the covering element. This pressure does not rise further than the selected weight of so far for example a pressure sensor or valve 2V/2W allows. The on the ribs 2E and 2F connected parts 1A preferably by nails 1C1 on the overlapping band ends 1C and connected thereto parts ID, IF and 1H are raised by the accumulated pressure between container substance and the device structure. Whereby, for the reason of higher length of the diagonal of the three connected ribs in straightened position between the hinge according figure 2A and the outer opposite end of rib 2F in comparison to the length of this same diagonal between 2A and the outer opposite end of rib 2F in resting position of the device moves, in case of accumulating pressure the surrounding floating body ID in the direction of the container wall until it squeezes against the container wall and the outer end of extension part 2G touches it. In an embodiment without extension 2G the surrounding floating body changes shape up to the ribs are fully straightened wherein the weight of the compartments 2Y the further rise of the rib-ends should hinder.

Due to the stretching movement over the entire circumference the device diameter increases as well the extent of the device in its entirety causing that the surrounding floating body as shown in figure 3A get squeezed between the very end of the ribs 2F and the by means of the stiff eners IE reinforces joined layer border around the straightened cover surface wherein a substantially gas-tight seal of the container IN is realized.

In figure 3 A is a cross section of the surrounding floating body ID in this position with straightened ribs and compartment 2Y in detail displayed. The part 3AA is preferable made of strips flexible and abrasion resistant waterproof material for example manufactured out of a with yarn reinforced polyurethane or PVC foil connected to each other and then joined with the outer long ends of parts 1A. This in such a way teardrop shaped floating body may be divided into compartments and reach by stretching of the ribs the round inner container wall. On which tangent plane possibly a second layer of abrasion resistant flexible material 3AB can improve the life expectancy of this part. The from one or a plurality of strips made part 3AA is for example by means of hot air welding connected to the sides of 3AC either at the air sides and / or substance sides at the edges of parts 1 A. To compensate the difference in peripheral of the outer periphery and the inner periphery of the surrounding floating body are for example wedges welded or for example a belt is either on or between the long sides is sealed considering a contraction between the parts to connect and the belt. Compensation can also to be realized by means of a heated welding foot combined with feed-in difference between the belt and the body to seal. Advantage of this processing is that the belt contributes to the rigidity of the outer border. The diameter of the formed tube can possibly be double the distance of the tip of part 2G and the tip of 2F. For the purpose of the insertion in the surrounding part 3AA of floating elements 3 AD made of for example bits cellular rubber and the liquid 3AE which is composed of for example water and an environmental safe antifreeze an at least hand large opening 3EF can be configured with for example a threaded cap. For drainage of the filling liquid as required during intervention activities are outlets 3AG disposed within reach of the filling fittings 3EF. The compartments2Y are possibly made out of the same foil type as the connected segments 1A and are located between the tips of the ribs 2F near to the surrounding floating body. Each of them also configured with a filling fitting or valve 3EF and outlet 3AG.

The volume of the surrounding floating body ID and compartments 2Y and their inserted quantity floating element has to be calculated for each single surface to cover considering that the for example cellular rubber blocks and the central floating body have to assure the floating properties of the entire device. The pressure between de device according figure 1 and the container substance 3AH is maximized by means of a sensor controlled gas pump placed somewhere in the system. The working pressure meets or is higher than the weight of the covering element and the frame of ribs counted together and can raise that far that a limited part of the central floating body and the surrounding body get lifted from the container substance.

Figure 4. Shows a schematic cross-section of the device in fully raised position of the ribs. As well as the hinges according to figure 2 A and figure 2B that contribute to the objective of the stretching of the ribs contribute the hinges of figure 2B and figure 2C, this last one here unlocked and both assembled with for example U-shaped profiles to installing the device, for container bottom cleaning and during removal out of the container.

After assembling the device on an open field located nearby the container to cover the entire device can be lifted and transported and then descend on the substance in the container. To this end, the hinges that are shown in Figure 2B are lifted by means of mounting ring 2B 1 for example manual at stage of emptiness by means of cables or with help of a crane in case of a filled up container, whereupon the hinges to lock shall be provided with nuts and bolts. The hinges according to figure 2C can be unlocked by removing one of the two sets screws, pipes and nuts similar to figure 2A before the lifting operation is started. Depending upon the filling level of the container a raised position of the ribs can be achieved either manual by means of cables and the mounting rings 2C1, with assistance of a crane or by means of a mechanized system. For this a cable 4B is connected to the double ring set 2J by means of the mounting rings 2J1 reaching through the central lid 1H of dome IF making the free hanging device steady against wind due to the weight of the central floating body. Cables 4B and an equal number of cables 4A as the number of rib-sets can be joined at a crone hanging underneath and become connected to the crane cable.

Figure 5. shows a perspective detail view of the self -opening service opening with the hatches closed. This service opening is used in the first instance to provide a mixer-arm an entrance to the container substance. The opening is positioned between two ribs 2E or 2F. This rectangular or eventual conical shaped component is surrounded by belts 1C in order to realize reinforcement for segment 1A. In resting position of the device the entire construction of the opening is carried by the container substance. Namely by the buoyancy of the beams 5A and the floating body 5J made of for example cellular rubber wrapped with a flexible water tight coated fabric. This flexible material might have thermoplastic properties what allows to weld the individual segments into one solid component that can be connected to the segment 1A and belts 1C and / or frame 51. Perpendicular to the ribs therefore, in parallel with the belts 1C are three of these beams positioned and two beams are in parallel of the ribs forming together two

compartments 5C and 5D. This floating body comprises at the top side of compartment 5C one or preferably a pair of equal made out of for example stainless steel hatches 5B connected to the floating body by means of hinges disposed parallel to the ribs on the floating beams. The hatches are possibly sealed gastight by means of one side adhesive cellular rubber tape. The weight of the hatches is chosen in such a way or are made heavier so that they won't open up by themselves at a for example 4 kgf/m² device working pressure. The compartment 5D is sealed gas tight by the surrounding floatable beams and the on these beams disposed for example stainless steel plate 5E. This plate 5E is configured with mounting rings 5F at the substance side that function for mounting a dobber fitting inside the compartment 5D that has a buoyancy or force larger than the weight of both hatches 5B to be used for lifting the hatches. Next to side of beam that separates the compartments 5C and 5D the dobber is configured with a for example stainless steel shackle 5H that is shaped to open the hatches while the device is moving into the resting position by means of the dobber getting lifted and pushing the hatches open at their touching edges. Conversely, with increasing pressure between the container substance and the device the dobber will hang down by means of its own weight lowering the shackle and closing the hatches. To this end, the angle of the opening of the hatches delimits and is a skirt with frame 51 with floats 5J made out of flexible self- floating material disposed at the substance side of the device. This serves to prevent gas at stage of opened up hatches to escape in open air what would hinder the desired buildup of pressure underneath the device. The skirt encloses to this purpose the floaters of the service-opening and reaches lower than the substance surface in both resting and straightened position of the device. The pressure within the space of the skirt, hatches and container substance is possible controlled by an independent from the device working pressure operating sensor or pressure control unit 5K.

Such service-opening mechanism is valuable for the use of the device because operators are not obliged to go and walk on the device in case of required frequent mixing to open up any hatches. This distinguishes both the device as well the service opening from any other known model of floating covers for containers.

Figure 5A. shows a schematic cross-section of the self-opening service opening with opened hatches. The dimensions of the compartments and the height of the skirt has to be determent for each single device to produce. For containers with a mixer placed at the bottom a service opening with four floating beams, one compartment 5C and hatches 5B is sufficient. The mixer at the container bottom could for example be configured with a shackle comparable with 5H shaped to open up the service opening at approaching the bottom during emptying the container. Conditional for the functioning of the opened hatches is that the device is not twisting around on the container substance that could be caused by wind or during operation of the mixer-arm. In case of for example a round containers may be provided therein by using a cord 6G and a mounting ring at one of the ribs 2F with gas closing grommet.

Figure 6. Shows a schematic cross-section of the device with a central dome in which the central floating body 2D is configured with fluid pump 6A, nozzles 6B and supply hose 6C. In the cutout 20 of the central floating body 2D is fluid pump 6A applied with a thereon connected hose 6C that is eventually configured with a filter. This fluid pump' s hose is pumping from a desired level of the container IN the liquid and sprays it via the for example seven nozzles over the container substance surface. The level of the inlet that eventually is configured with a filter 6C1 is eventually adjustable in position by means of a winch and cable placed on the container wall that is connected to the hose via a gas tight throughput in the floating device.

The anchorage 6D through cables and mounting rings at for example the container bottom and the central floating body 2D minimize the rising level of the floating device. In case of a too high fill level of the container or foaming the device won't get damaged in spite of the fastenings 6D. In such an event will hinge according to Figure 2A not impede the further rise of the ribs and hence also the covering element. Under such conditions hinge according to Figure 2B will nod and therewith release the curved extension 2G and / or the surrounding floating body ID and thereto attached straight ribs from the container wall getting space to move freely along the wall. The liquid excess, or foam may end thereby flowing over the container edge without damaging the device or eventually even push over the edge. Due to this capability this device distinguish itself not only from other know floating covers either fixed shaped or flexible but also from the none- floating types that are fixed to the container wall either with or not configured with a column. In biogas installations is foaming a recurring problem causing frequently irreparable damage to the costly covers.

Figure 7. is a schematic perspective view of the device as shown in figure 1 illustrated with a dome IF and a central lid 1H. The dome is made of connected pie -piece like shaped segments but cut with rounded lines 1 AC, here illustrated in line with 1 AA and rounded line IAD illustrated in line with straight line 1AB of figure 1. In practice and preferable these lines will skip in order to avoid here unwanted thickness and stiffness of multiple connected layers. The convex connected lines 1 AC and IAD form a dome shape of flexible material that can be configured with disk- shaped lid which construction covers the central floating body in resting position of the ribs. The third cutting line is connected to the fitting topped segments of Al or with a collar 1A1 according figure 2B. This design with dome is preferred above the design of figure 1 in which the required space is shaped cut out in one piece with the segments 1A. In order to provide access to the central floating body lid 1H is connected to the tips of the segments.

It is noted, that the invention is not restricted to the above described embodiments, but also comprises to other variants within the scope of the hereto appended claims.

Claims

1. Device for covering a container for containing a gas-comprising and/or gas-producing substance, comprising:

- a central support member;

- a covering element extending from the central support member;

- at least one floating body disposed close to the outer periphery of the covering element and connected thereto,

characterized in that the device comprises first hinge means for pivotally connecting the covering element to the central support member such that the covering element is pivotable between a first position, in which the covering element extends substantially parallel to a longitudinal axis of the central support member, and a second position in which the covering element extends substantially transversely of the longitudinal axis of the central support member.

2. Device as claimed in claim 1, wherein the covering element comprises second hinge means connected at a determined distance from the central support member to the covering element, which second hinge means are configured to divide the covering element into two first peripheral parts pivotally displaceable relative to each other such that the two first peripheral parts are displaceable between a first, folded position, in which the inner surfaces thereof extend at an angle greater than 180° relative to each other and in which during use of the device at least one peripheral part of the two peripheral parts extends substantially flat on and parallel to the substance, and a second, straightened position in which they extend substantially in one plane and in which during use of the device they extend substantially obliquely upward relative to the substance from a peripheral wall of the container to the central support member, and wherein during use of the device the two first peripheral parts are configured to displace from their first position to their second through a gas pressure being exerted.

3. Device as claimed in claim 2, wherein during use of the device the second hinge means are disposed on a side of the covering element remote from the substance.

4. Device as claimed in claim 2 or 3, wherein the at least one floating body extends over substantially the whole outer periphery of the covering element and is configured to extend, in the second position of the two first peripheral parts, between the peripheral wall of the container and the covering element during use of the device.

5. Device as claimed in any of the foregoing claims, wherein the covering element com- prises third hinge means connected at a determined distance from the central support member to the covering element, which third hinge means are configured to divide the covering element into two second peripheral parts pivotally displaceable relative to each other such that the two second peripheral parts are displaceable between a first folded position, in which they extend substantially parallel to each other, and a second straightened position in which they extend substantially in one plane, which third hinge means comprise connecting means for connecting the third hinge means to lifting means for raising the device, wherein in a raised position of the device the two second peripheral parts are configured to be located in their first position.

6. Device as claimed in claim 5, wherein the third hinge means comprise locking means for locking the two second peripheral parts in the second position.

7. Device as claimed in at least claims 2 and 5, wherein the second hinge means are disposed between the third hinge means and the central support member.

8. Device as claimed in any of the foregoing claims, wherein the central support member takes a buoyant form.

9. Device as claimed in any of the foregoing claims, wherein the covering element takes a flexible form.

10. Device as claimed in claim 9, wherein the covering element comprises a number of ribs extending from the central support member and connected to the covering element, wherein:

- the first hinge means are connected to the ribs;

- optionally the second hinge means are connected to the ribs, and

- optionally the third hinge means are connected to the ribs.

11. Device as claimed in any of the foregoing claims, comprising connecting means for connecting gas outlet means for discharging gas during use of the device from a space defined between the covering element and the substance.

12. Device as claimed in any of the foregoing claims 1-11 and 2, comprising an opening with a closing element, which closing element is displaceable between a first position, in which the closing element leaves the opening clear, and a second position in which the closing element closes the opening, which closing element comprises floating means such that the closing element is configured during use of the device to float on the substance and due to its buoyancy is configured to be situated in its first position in the first position of the two peripheral parts and to be situated in its second position in the second position of the two peripheral parts.

13. Assembly of a container for containing a gas-comprising and/or gas-producing substance and a device for covering the container as claimed in any of the claims 1-12, wherein the container comprises a bottom and a peripheral wall extending upward from the bottom, wherein the device is disposed in the container and the covering element extends in its second position from the central support member to the peripheral wall of the container.

14. Method for arranging a device for covering a container for containing a gas-comprising and/or gas-producing substance as claimed in any of the claims 1-12, comprising the steps of:

(b) displacing the covering element to its second position.