STRICTION

The present disclosure is related to an apparatus and a method handling of a bellow or bladder that has been utilized in a chamber such as for example a vessel for a gaseous chemical. More particularly, the disclosure is related to an apparatus and a method for, in an effective and controlled manner, extracting an inflated bellow or bladder through a constriction bridging a chamber and a compartment.

The bladder may be elastic or substantially inelastic of a type suitable for use as a volume- displacing device in a chamber such as for example an LPG-tank in an LPG transport ship. A bladder or bellows intended for this purpose is disclosed in publication

W02006/033577 A1 which discloses a method related to change of cargo of a transport vessel having at least one fluid container containing a first fluid comprising a liquid phase and a gas phase. A second fluid is introduced into a bladder which is situated inside the fluid container. The expansion or filling of the bladder reduces the internal volume of the fluid container which is available for said gas phase.

The method disclosed in W02006/033577 A1 comprises inter alia the following steps:

- a) ventilating the fluid container by filling the bladder with said second fluid such that the amount of gas phase which is to be vented by an inert gas, is limited to a volume de fined by the internal surface of fluid container and the external surface of the bladder; and

- b) replacing the inert gas, such as for example N2 in said volume with the gas phase of the following cargo. Thus, W02006/033577 A1 discloses an efficient manner in which a gas is ventilated from an enclosure such as a tank. Whilst the bladder is inflated using said gas, a gas on the out side of the bellows or bladder is allowed to escape through at least one aperture, or con duit, and into another area for safe keeping and/or processing. Once the bladder has been completely or nearly completely inflated, almost all of gas on the outside of the bladder is thus displaced though said apertures or conduits.

Publication WO 2014/070021 A1 discloses an apparatus and a method for facilitating purging a vessel by means of an inflatable bellows or bladder. The bladder is connected to a conduit for communicating a fluid into or out of the bladder. The bladder is initially ar ranged in a fluid tight compartment outside the vessel. The compartment is provided with a closable sealing means adapted for selectively bringing the compartment in fluid com munication with the internal of the vessel via an aperture in a portion of the vessel.

The aperture may typically, but not exclusively, be a so-called manhole. At least a portion of the bladder is then brought into the vessel. Thereafter, the bladder is inflated by means of a fluid provided from a fluid source. When the bladder has been inflated, the vessel is cleaned by purging a space which is defined by an internal surface of the vessel and an external surface of the inflated bladder. When the cleaning process has been completed, the bladder is deflated and thereafter brought out of the vessel and back into the compartment.

The bladder used for insertion into a first tank described in W02014/070021 Al, is typi cally folded inside a cartridge when it is inserted into the second adjacent tank prior to use. Upon deployment, the bellows or bladder is typically falling from its cartridge in the second, adjacent tank into the first tank such that the filling end of the bladder is retained inside the second, adjacent tank. The filling end is a narrow portion of the bladder ex tending from its termination point inside the second, adjacent tank into the vessel so that it forms a "neck" on the main bladder, which is intended to inflate in the first tank. The bladder is folded in such a manner so as to avoid twist, which would impede the flow of gas into the bladder once it is dropped into the first tank.

Once the bladder has served its purpose, it is typically deflated as much as possible by means of filling a gas on the outside of the bladder inside the first tank in which it has been deployed. This deflation method, although reliable, is not guaranteed to expel all the gas from the bladder. Thus, the remaining gas inside the bladder must be allowed to escape prior to the bladder entering a collection means inside the compartment.

One of the great advantages of the apparatus and method disclosed in W02014/070021 A1 is that the insertion, inflation, deflation, and removal of the bladder may be remotely controlled without a human having to expose him-/herself to the atmosphere in the ves sel once the bladder has been initially installed in the compartment. This important ad vantage is applicable also for the apparatus according to the present invention.

The apparatus and method disclosed in W02014/070021 A1 works satisfactorily. Howev er, experiences show that there may be instances in which it is difficult to completely de flate the bladder, i.e., completely remove all the gas inside the bladder before the bladder is pulled from the vessel through the aperture separating the vessel from the compart ment and further onto or into the drum as disclosed in WO 2014/070021 Al. In such in stances the gas trapped inside the bladder will tend to accumulate inside the diminishing volume of the remaining bladder during the pulling process. As the bladder is being pulled through the aperture between the vessel and compartment, the remaining gas volume inside the bladder will tend to inflate the remainder of the bladder being "upstream" of the aperture, i.e., the portion of the bladder still being inside the vessel. This inflated por tion being upstream of the aperture in the vessel will tend to fully block the aperture be tween the vessel and the compartment. If the pulling operation continues, the gas pres sure within the inflated portion of the bladder being upstream of the aperture will increase and represent a high risk of bladder rupture. If, or rather when, such a rupture occurs, the gas from inside the bladder will blend with that of the gas on the outside of bladder inside vessel. A person skilled in the art will appreciate that such a blend of gases is highly undesirable and counterproductive to the intended goal of the invention.

Even though it should be expected that any cutting of the bladder into elongate strips when wound onto or into a collection drum in the compartment during its extraction from the vessel through the aperture should allow for the gas to escape from the bladder, experiences show that this is not always so.

The apparatus and method disclosed in WO 2020/15B852 is intended to alleviate this challenge by cutting slits into portions of the bladder as a response to the resistance ex perienced by the pulling mechanism located above the cutting device. The slits being a plurality of holes or longitudinal slits or any other geometry, are intended to allow the gas emanating from the bladder to escape therethrough during its extraction from the cham ber to the outside chamber. Whilst the apparatus disclosed in WO 2020/153852 is effec tive in bringing about slits in the appropriate section of the bladder, the puckering of the bladder in way reduces the effective opening of the slits through which the gas is allowed to escape. Experiences show that the net result is that effectiveness intended brought about through the implementation of the technique disclosed in WO 2020/153852 is lim ited.

Another phenomenon associated with the exhaustion of the bladder is the pressure drop inside the neck (or rather the portion of the bladder, which at any one time is located in way of the aperture during extraction) caused by the increased fluid velocity through this section during deflation. Although there is a certain stretch in the neck caused by the ex traction of the bladder, the resulting "stiffness" in the neck is too little to withstand col lapse caused by even a moderate gas velocity in this section. Once a collapse situation has occurred, the pressure gradient inside the "neck" must be reversed in order to re establish a fluid flow in the section.

There is a need for an apparatus and a method providing an improved deflation rate of the bladder combined with lower failure rate during operation.

The invention has for its object to remedy or to reduce at least one of the drawbacks of the prior art, or at least provide a useful alternative to prior art.

The object is achieved through features, which are specified in the description below and in the claims that follow.

The invention is defined by the independent patent claims. The dependent claims define advantageous embodiments of the invention. In a first aspect of the invention there is provided an apparatus for facilitating deflation and pulling of a bladder of a bladder assembly through a constriction bridging a chamber and a compartment comprising a bladder pulling mechanism and a bladder assembly cut ting device. The pulling mechanism comprises a guiding device operatively connected to at least two spaced-apart portions of the bladder assembly. The bladder assembly cutting device is configured for splitting at least the bladder of the bladder assembly in at least two portions, the bladder assembly cutting device operating between the spaced apart portions of the bladder assembly, wherein the guiding device is configured for at least temporarily increasing a distance between the split portions of bladder assembly after at least the bladder being subject to the bladder assembly cutting device, thereby facilitating deflation and pulling of the bladder through the constriction. Thus, when cut and directed in this manner, the bladder does not pucker into gradually smaller cross sections than that of the section where it is cut. The net result is that the fluid velocity is kept under control at this critical section.

In what follows, the bladder assembly cutting device will also be denoted bladder cutting assembly, or simply cutting/cleaving device.

In one embodiment, the bladder cutting device is configured to span at least the diame ter, or characteristic section measure, of the constriction through which the bladder is to be extracted. The constriction will hereinafter also be denoted aperture. Preferably, the bladder cutting device being arranged such that it cuts the entire bladder neck during its extraction in a plane parallel or substantially in parallel with the direction of extraction.

It is an advantage if the cut sections of the bladder are evacuated or pulled from the cut ting area at similar, or substantially similar, rate over time so as to ensure the cutting plane remains the same, or substantially the same, as that of the cutting device so that any imbalance of bladder material accumulation at the constriction is avoided.

In one embodiment of the present invention the cut sections of the bladder downstream of the cutting device, i.e., the bladder that has passed the cutting device and has been separated, is lead in opposite direction from the cutting plane. This may be done by lead ing the separated cut sections via combination of guides and rollers such that they are brought onto separate collection means arranged within the compartment some distance downstream the cutting device.

In another embodiment of the present invention the cut sections of the bladder down stream of the cutting device are lead in opposite direction from the cutting plane. This may be done by leading the separated cut sections via combination of guides and rollers such that they are brought onto a common collection device arranged within the com partment some distance downstream the cutting plane.

During its operation the bladder is subject to inflation (commencing the operation) and deflation (finalizing the operation). It should be appreciated that the bladder will normally be shaped in an approximate geometry and oversized volume to that of the chamber in which the bladder is intended for use. From this it follows that the bladder will be provid ed with a "neck" or filling line in way of the adjacent compartment from which it is being launched when commencing the operation.

Once the bladder is fully deployed into the chamber in which it shall operate, it is appre ciated that there is a filling neck fitted inside the compartment initially holding the blad der. As will be disclosed below, the bladder may be initially stored in a cartridge for ex ample of a type disclosed in W02014/070021 Al. Such a cartridge is arranged within the compartment. When starting the operation, a main body of the bladder is dropped from the cartridge into the chamber, while the neck of the bladder is secured to a portion of the cartridge.

Once the bladder has completed its operation, it is deflated and retrieved from the chamber. The deflation and retrieval are initiated by deflation and later followed by re trieval whilst still deflating, i.e., releasing the remainder of the fluid still left inside the bladder. As the full section of the bladder is being pulled through the constriction or aper ture between the chamber and adjacent compartment, an effective area available for fluid flow is restricted by the gathered bladder material over such a relatively small cross section. This restricted effective area increases the fluid velocity and may cause collapse if not restrained. The inventor has found two effective solutions for mitigated or reducing such a collapse: A first solution is to shorten the neck length, and a second solution is to counter the tendency for collapse by means of structural support.

In accordance with the first solution, the guiding device may comprise first guiding ele ments and second guiding elements, the second guiding elements and the cutting device configured for moving between a passive position and an active position, the second guiding elements and the cutting device being closer to the constriction when being in the active position than in the passive position.

The bladder assembly may comprise a cartridge operatively connected to a portion of the bladder, the cartridge being configured for housing the bladder prior to inserting a por tion of the bladder into the chamber and inflating the bladder. In addition to holding the bladder in an orderly manner prior to use, the cartridge may act as a "mouthpiece" through which the fluid flows into a portion of the bladder that has been deployed past the construction. Once deflation of the bladder is initiated, the cartridge has served its purpose and may, like the bladder, be split apart into separate sections along with the rest of the bladder material being retrieved past the restriction.

The cartridge may be splitable by one of, or a combination of the bladder cutting device and the pulling device wherein the bladder is subject to a cutting in combination with a tearing from the pulling device. A combination of cutting and tearing facilitates the sepa ration of the cartridge into portions.

It is an advantage if the bladder assembly further comprises an extendable structural member configured for reducing a risk of the bladder being collapsed when passing through the constriction when being pulled and deflated. Thus, the extendable structural member represents the second solution for mitigation or reducing a collapse of the neck as discussed above. Preferably, such an extendable structural member may comprise at least one coil operatively connected to the cartridge, the coil being configured for exten sion between a retracted first position wherein the coil is housed within the cartridge, and an extended second position wherein the coil extends past the constriction and into the chamber. In one embodiment, the at least one coil may be arranged such that it/they remain fixed to both the cartridge and the guiding device. Preferably, the at least one coil is arranged such that it/they hang supported from the cartridge and into the "neck" of the bladder, to form a helix curve of substantially constant helix angle. In such a preferred embodiment, the at least one coil is deployed for the entire depth of the bladder within the chamber such that the at least one coil remains in the "neck" section of the bladder throughout the entire, or almost entire, retrieval process. The at least one coil may be of a type being similar to that commonly utilized as a "skeleton" in extendable air hoses hav ing a relatively large cross-section area.

In one embodiment of the invention, the compartment may be provided with a floor for carrying the cartridge, the floor being provided with an aperture adjustable between a first opening size wherein the cartridge is supported, and a second, wider opening. A pur pose of the second, wider opening is to facilitate splitting of i.a. the cartridge at a blunt angle and without the cartridge "snagging" against a perimeter of the aperture. Thus, the split cartridge is allowed wider space to be stretched apart during a retrieval through the constriction. The first opening size may in one embodiment be substantially zero.

In a second aspect the invention there is provided a method for facilitating deflation and pulling of a bladder of a bladder assembly through a constriction bridging a chamber and a compartment comprising a bladder pulling mechanism and a bladder assembly cutting device. The method comprises:

- providing an apparatus according to the first aspect of the invention;

- activating the bladder pulling mechanism to pull the bladder towards the cutting device to split at least the bladder; and

- at least temporarily increasing the distance between the split portions of the bladder by means of the guiding device.

The method may further comprise lowering second guiding elements of the guiding de vice, and the cutting device towards the constriction when activating the bladder pulling mechanism. This has the effect of reducing a length of the neck of the bladder. A reduced neck has the effect of alleviating the restriction in gas release rate from the bladder caused by both limited area through which to release the gas from the bladder as well as to provide means to improve the internal stiffening in the "neck" section of the bladder during deflation. The net result is improved deflation rate of the bladder combined with lower failure rate during operation.

In the following is described an example of a preferred embodiment illustrated in the ac companying drawings, wherein:

Fig. la shows a principle embodiment of the apparatus according to the invention prior to releasing a bladder into a chamber in the form of a vessel;

Fig. lb shows in larger scale detail A in fig. la;

Fig. 2 shows the apparatus in fig. la after the bladder and a structural member have been released from a cartridge, and filling of the bladder has com menced; Fig. 3 shows the apparatus in fig. 2, but wherein the bladder and the structural member are in the process of being split and pulled out of the vessel, while a fluid content within the bladder being exhausted;

Fig. 4 shows the apparatus in fig. 3, wherein all of structural member and a major portion of the bladder have been retrieved from the vessel; and Figs. 5a and 5b show an embodiment of a floor within the compartment, wherein the floor is provided with an aperture adjustable between a first opening as shown in fig. 5a and a second, larger opening as shown in fig. 5b.

Positional indications refer to the position shown in the figures. Similarly, denominations like upstream and downstream refer to the position shown in the figures.

In the figures, same or corresponding elements are indicated by same reference numer als. For clarity reasons, some elements may in some of the figures be without reference numerals.

A person skilled in the art will understand that the figures are just principle drawings. The relative proportions of individual elements are also strongly distorted. In the figures reference numeral V denotes a chamber in the form of a vessel or tank for holding various fluids, and wherein a cleaning or purging of the vessel is required after emptying a first fluid from the vessel fluid, and before filling a second fluid into the vessel. To facilitate cleaning of the vessel, a bladder or bellow may be utilized, as discussed in W02014/070021 Al.

The vessel V is shown disproportionally small relative to the apparatus 1 according to the present invention. The apparatus 1 is configured inter alia for deflating and pulling of a bladder 3 of a bladder cartridge assembly 3, 11 through a constriction 9, here shown as an aperture 9 in the form of a conduit bridging the internal of the vessel V and the com partment 5. The compartment 5 comprises a bladder pulling mechanism 8 and a movable bladder assembly cutting device 4.

In the embodiment shown in the figures, the bladder pulling mechanism 8 is a drum op eratively connected via a guiding device 6, 6', 10 to two spaced-apart portions of the bladder cartridge assembly 3, 11. In the embodiment shown, the bladder cartridge as sembly is in the form of the bladder 3 having a top portion secured to a splitable cartridge 11, and the guiding device is in the form of rollers 6, 6' for guiding forerunners 10.

The bladder cutting device 4 is configured for splitting or cleaving at least the bladder 3 of the bladder cartridge assembly 3, 11 in two portions, and operates between the spaced- apart portions of the bladder assembly 3. The guiding device 6, 6', 10 is configured for at least temporarily increasing a distance between the split portions of bladder assembly 3, 11 after being subject to the bladder cutting device 4, thereby facilitating deflation and pulling of the bladder 3 through the constriction 9.

It should be noted that cutting device 4 may be configured for cutting the bladder assem bly 3, 11 into more than two portions, for example three or four portions. It should also be noted that in one embodiment the cutting device 4 may be configured for cutting only the bladder 3 of the bladder cartridge assembly 3, 11. In such an embodiment, the car tridge 11 itself may be split by tearing along perforation lines 11' as will be discussed be low. Fig. la shows the apparatus 1 according to the invention prior to releasing the bladder 3 into the vessel V. The apparatus 1 is arranged on top of an aperture 9, such as a conduit bridging the internal of the vessel V and the compartment 5. A conduit like this may be similar to a so-called manhole. The aperture 9 form a restriction between the internal of the vessel V, and the compartment 5. The aperture 9 comprises a closable sealing means 7 which in fig. la is in a closed position to prevent fluid communication between the in ternal of the vessel V and the compartment 5 of the apparatus 1. The sealing means 7 may be a valve of a type known per se.

The bladder 3 is stored folded within the cartridge 11 and is connected to forerunners 10 forming part of the guiding device which also comprises rollers 6, 6'. The forerunners 10 are connected to the bladder pulling mechanism, here in the form of a drum 8. As will be discussed in more detail below, the guiding device 6, 6', 10 is configured for providing a radial pulling force component to facilitate "tearing" apart the portions of the bladder 3 that has been subject to the cutting device 4 and split as best seen in fig. 4. The radial pulling force component may also effect splitting of the cartridge 11.

The bladder cartridge assembly 3, 11 is set to rest on a variable geometry floor 14 as shown in figures 5a and 5b to enable lowering of the cutting device 4 and movable guide rollers 6' assembly during later retrieval, as is shown through figures 3 and 4. The variable geometry floor 14 is configured for adjusting a size of an aperture therein between a first opening size as shown in fig. 2, and a second opening size, see figures 3 and 4, being larg er or wider than the first opening size. The purpose of providing the larger second open ing size is to facilitate splitting of the cartridge 11 and the bladder 3 at a blunt angle and without the cartridge 11 and the bladder 3 "snagging" against a perimeter of the aperture of the floor 14. Thus, the split cartridge 11 and the bladder 3 is allowed wider space to be stretched apart during a retrieval through the constriction. In one embodiment (not shown), the first opening size may be substantially zero, i.e., the floor 14 being substan tially closed.

Guide rollers 16 are arranged below the floor 14. A primary purpose of the guide rollers 16 is to guide the bladder 3 past the periphery of an opening in the floor 14 when the bladder 3 is pulled from the vessel V and into the compartment 5, as shown in figures 3 and 4. Without the guide rollers 16 and the wide opening of the aperture of the floor 14 as shown in figures 3 and 4, the cartridge 11, the bladder 3 and the structural member would be prone to snagging against the perimeter of the opening of the floor 14 while being pulled out from the vessel V.

Fig. lb shows in a larger scale detail A in fig. la, and shows a view of the cartridge assem bly 3, 11 wherein the bladder 3 is packed inside a cartridge 11. The cartridge 11 is splita- ble along a perforation line 11' such that when the forerunners 10, which is connected to the cartridge 11, are subject to a tension from the collection drum 8 and being pulled to wards the collection drum 8, the cartridge 11 splits along said perforation line 11'.

The cartridge assembly 3, 11 is further provided with an extendable structural member 12 arranged in a top portion thereof. In the embodiments shown in figures 2 and 3, the ex tendable structural member 12 is in the form of two coils. The extendable structural member 12 is operatively connected the forerunners 10 such that it will follow the fore runners 10 when these are being pulled toward the collection drum 8 once the bladder 3 is being retrieved subsequent its intended use. The extendable structural member 12 may be made from a material configured to be split by the cutting device 4.

To facilitate release of the bladder 3 from its storage position within the cartridge 11, the bladder 3 may be folded in an "accordion-form" within the cartridge 11. Thereby, the bladder 3 will deploy from the cartridge 11 when being released through a removable bottom cartridge seal 13 of a type known per se. In one embodiment the bottom car tridge seal 13 may for example be a sheet or film being removed when securing the car tridge 11 holding the bladder 3 to the floor 14. In one embodiment the sheet or film is teared up by the floor 14 when the opening size of the floor is changed from its first size to its second size, as discussed above. Thus, upon release from the cartridge 11, the blad der 3 falls by gravity through its own neck, which in turn is attached to the periphery of the splitable cartridge 11. Since the splitable cartridge 11 is connected to the forerunners 10 and the bladder 3 is connected to the cartridge 11, the bladder 3 will be retracted to gether with the cartridge 11 and the extendable structural member 12 when subject to a pull by means of the forerunners 10 towards the collection drum 8.

In fig. 2, the bladder 3 has been released into the vessel V from the compartment 5. The bladder 3 is being filled with a fluid from inside the compartment 5. It should be appreci ated that the compartment 5 is in fluid communication with a source of compressed fluid (not shown) during filling of the bladder 3. When deploying the bladder 3 from the car tridge 11 into the vessel V, the structural members 12 extends from a top portion of the cartridge 11 to which it is secured, inside the neck of the bladder 3 secured to an inside the cartridge 11, and into the bladder 3 within the vessel V. The top of the neck or "filling line" of the bladder 3 is attached to the top of the splitable cartridge 11 such that the bladder 3 is open to fluid entry from the compartment 5. Attached to the top of the splitable cartridge 11 is, as mentioned above, the extendable structural members 12 and the forerunners 10. The extendable structural members 12 urges the neck of the bladder 3 radially towards the splitable cartridge 11, thereby ensuring that the neck of the blad der 3 remains in an open, expanded position during filling fluid into the bladder 3.

Fig. 3 shows an embodiment of the apparatus 1 according to the invention in a situation where fluid from within the bladder 3 is being exhausted from inside the bladder 3 and into the compartment 5. It should be appreciated that the compartment 5 is provided with a means (not shown) for communicating fluid to an outside of the compartment 5, for example to a fluid collecting means or to the atmosphere.

In fig. 3, the second guiding elements 6' and the cutting device 4 have moved from its passive position shown in fig. 2, to its active position being closer to the aperture 9 bridg ing the compartment 5 and the internal of the vessel V. Thereby, an effective length of the neck of the bladder 3 is reduced during its exhaustion and extraction. In one embod iment, the movable guide rollers 6' and cutting device 4 is prevented from moving from their passive position (as shown in figures la and 2) to its active position as shown in fig. 4 until the adjustable aperture of the floor 14 has been adjusted from its first, small open ing size as indicated in fig. 5a, to its second, large opening size as indicated in fig. 5b.

Further in fig. 3, a rotation of the collection drum 8 has started as indicated by arrow R, and the forerunners 10 running via the guide rollers 6, 6' are pulled towards the collec- tion drum 8 with a force sufficient to allow the splitable cartridge 11 to be split and pulled onto the collection drum 8 along with a portion of the bladder 3 and ditto from the coiled structural members 12. The bladder 3 is now in a position for continuous retrieval from the vessel V through the restriction or aperture 9 via the guide rollers 16 below the floor 14, the cutting device 4 and the second, movable rollers 6' such that the forerunners 10 gradually are made up by or replaced by the split sections of the bladder 3 and a por tion of the coiled structural members 12, as indicated in fig. 4.

In fig. 4, all of structural member 12 and a major portion of the bladder 3 have been re trieved from the vessel V and spooled onto the drum 8. When all of the bladder 3 has been pulled out of the vessel V and spooled onto the drum 8, the drum 8 comprising the split bladder 3, structural member 12, and the cartridge 11, may be brought out of the compartment 5, and replaced with an empty drum 8 ready for subsequent use. After clos ing the sealing means or valve 7 of the aperture 9, the vessel V is ready for a new load of fluid.

It should be noted that a cleaning or purging process of the vessel V is commenced when the bladder 3 is fully inflated within the vessel V, as disclosed in WO 2014/070021 A1 dis cussed above.

Figures 5a and 5b discloses an example of a variable geometry floor 14 wherein, wherein an opening of the floor 14 is controlled by means of lamellar diaphragms 15 in the form of displaceable, semi-circular disks. The two squares indicate maximum and minimum open ings of the floor 14.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embod iments without departing from the scope of the appended claims. In the claims, any ref erence signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.