Introduction

The present invention relates to a hose arrangement for transferring a flowable medium between a first unit and a second unit in a marine environment. The hose arrangement comprises a hose unit comprising a first end portion adapted to be connected to the first unit and a second end portion adapted to be connected to the second unit. The hose unit further comprises a first conduit adapted to transfer the medium and a second conduit arranged around the first conduit so that a closed space is formed between the first conduit and the second conduit.

Prior art

Hose units are used in variously industrial applications, such as marine environment, for transferring a flowable medium between a first unit and a second unit. For example, in off-shore oil production, large amount of flowable medium is produced that needs to be transported for further processing. Large amount of fluids are also used in the production and accordingly needs to be transferred to the production site. Flexible hose units are in particular suitable for transferring flowable medium in a dynamic environment, such as between an oil rig and a vessel.

The flowable medium may be a liquid or a flowable solid, such as powder with grain size that enables it to be transferred using the hose unit. The flowable medium may also comprise a mixture of different phases, such as a slurry of liquid and solids. These solids may be abrasive and result in internal fractures in the hose unit. The medium is for example oil, water, drilling fluid, drilling mud, and etcetera.

A problem with prior art hose arrangements is that it is difficult to quickly detect an operational change of the hose arrangement, such as a small leakage of one of the first and the second conduit during transferring the medium between the two units. Prior art leak detection is based on determining a difference between the amount of the medium transferred from one of the units and the amount received by the other of the two units. In that the hose unit normally is used for transferring large amount of the flowable medium at a high flow rate, a small leakage of the medium is usually not detectable. In particular, it is difficult to detect small a fracture of the hose unit that relates to an internal leakage that is not detectable using external visual inspection. However, such small fracture may, due to the high flow rate in the hose unit, rapidly increase the fracture to an external leakage to the environment. In the worst case scenario, the small fracture may rapidly evolve to a catastrophic rupture of the hose unit with significant leakage of the medium to the surrounding. Apart from the possible environmental consequences of such leakage, special adapted fluids, such as drill fluid, are expensive to replace. Accordingly, in order to avoid such catastrophic leakage of the medium, it is desirable to be able to detect small internal fractures at an early stage and terminate the transfer of medium before the fracture results in a catastrophic rupture of the hose unit.

The operational change may also relates to a separation of two parts of the hose unit that are connected by means of a stress release unit. The separation of the stress release unit occurs when the stress in the hose unit exceeds a certain level. While the separation of the stress release unit is detectable by viewing the hose unit during the operation, it is desirable to detect the separation in a quickly and reliable manner.

WO2010041955A1 discloses a hose system comprising an inner hose, an outer hose and an air filled volume between the inner hose and the outer hose for providing buoyancy to the hose system.

WO2009/082241 A discloses a safety hose for transferring fluids between a floating structure and another fixed or floating structure.

Summary of the invention

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. In particular, an object of the invention is to provide a hose arrangement that enables detection of different operational changes of the hose unit in a quick and reliable manner.

These objects are achieved by means of a hose arrangement for transferring a flowable medium between a first unit and a second unit in a marine environment according to claim 1 , wherein the hose arrangement comprises a hose unit comprising a first end portion adapted to be connected to the first unit and a second end portion adapted to be connected to the second unit, wherein the hose unit further comprises a first conduit adapted to transfer the medium and a second conduit arranged around the first conduit so that a closed space is formed between the first conduit and the second conduit.

The hose arrangement is characterized in that the hose arrangement comprises a loop arrangement comprising an inlet for injecting a gas into the space and an outlet for removing the gas from the space, wherein the hose arrangement comprises sensor means that is adapted to sense the pressure of the gas or an entity dependent on the pressure of the gas that is being conducted in the loop arrangement, and a logic unit adapted to receive information from the sensor means and in dependency of said received information determine a significant change in the pressure or the entity dependent on the pressure that is related to a change in the operational condition of the hose unit.

By means of measuring the pressure of the gas or an entity dependent on the pressure of the gas that is conducted in the loop arrangement and on basis thereof determining the significant change in the pressure, a change in the operational condition of the hose unit can be detected. Thereby, it is possible to stop the operation of the hose arrangement before change in the operational condition result in a further change in the operational condition, such as a catastrophic rupture of the hose unit.

According to an embodiment of the invention, the logic unit is adapted to determine a first significant change comprising a first decrease in the pressure or an entity dependent on the first decrease in the pressure that is related to a change to a first operational condition comprising a leakage of the second conduit.

When a leakage occurs in the second conduit, parts of the gas is escaping through the opening at the leakage. Thus, not all of the gas that is introduced into the inlet is exiting the outlet of the loop arrangement. Accordingly, the leakage of the second conduit result in that the pressure of the gas that is exiting through the outlet is decreasing compared with normal operation without any leakage. By means of identifying the first significant change that is related to the first decrease in pressure or an entity dependent on the first decrease in the pressure, the change to the first operational condition comprising a leakage of the second conduit can be detected by the logic unit of the hose arrangement.

According to an embodiment of the invention, the hose unit comprises a first portion comprising the first end portion and a second portion comprising the second end portion, and wherein the logic unit is adapted to determine a second significant change comprising a second decrease in the pressure or an entity dependent on the second decrease pressure that is related to a change to a second operational condition comprising a separation of said first portion from said second portion of the hose unit.

According to an embodiment of the invention, the hose unit comprises a stress release unit arranged between said first portion and said second portion adapted to allow the first portion and the second portion to be separated from each other when the hose unit is subjected to stress exceeding certain level.

According to an embodiment of the invention, the stress release unit comprises means for closing the first conduit in dependency of a separation of the first portion and the second portion, and wherein the stress release unit is configured to maintain the loop arrangement without obstruction regardless of a separation of the first portion and the second portion.

When the first portion and the second portion of the hose unit are separated from each other, such as by means of the separation of the stress release unit, in principal all gas introduced into the inlet is released to the atmosphere and in principal no gas is exiting through the outlet. Accordingly, the separation of the first portion of the hose unit from the second portion of the hose unit results in that the pressure of the gas that is exiting through the outlet is decreasing compared with normal operation without any leakage. Moreover, the pressure is decreasing to a larger extent than in the event of a leakage of the second conduit. By means of identifying the second significant change that is related to the second decrease in pressure or an entity dependent on the second decrease pressure, the change to the second operational condition comprising a separation of the two portions can be detected by the logic unit of the hose arrangement.

According to an embodiment of the invention, the logic unit is adapted to determine a third significant change comprising an increase in the pressure or an entity dependent on the increase in the pressure that is related to a change to a third operational condition comprising a leakage of the first conduit.

When a leakage occurs in the first conduit, parts of the medium that is being conducted between the first unit and the second unit are conducted into the spacing through the opening at the leakage. Thereby, the volume of the spacing is restricted by the medium introduced, which results in a pressure increase of the gas being feed in the loop arrangement. By means of identifying the third significant change that is related to the increase in pressure or an entity dependent on the increase in the pressure that is related to a change to a third operational condition, the change to the third operational condition comprising a leakage of the first conduit can be detected by the logic unit of the hose arrangement.

According to an embodiment of the invention, the sensor means comprises pressure sensor means arranged to sense the pressure of the gas that is conducted through the space.

According to an embodiment of the invention, the sensor means comprises a gas volume sensor device arranged to sense the flow of the gas that is conducted through the space.

According to an embodiment of the invention, the sensor means is arranged to sense the pressure of the gas after that the gas has been conducted through the inlet and the outlet.

According to an embodiment of the invention, said space is arranged to collect a leakage of the medium and the hose arrangement comprises a container to which said leakage is adapted to be evacuated and a leakage sensor means for sensing a receipt of said leakage in the container, wherein the logic unit is adapted to receive information from the leakage sensor means and determine a fourth significant change relating to said leakage. The gas of the loop arrangement passes the spacing and is adapted to evacuate a leakage that has been introduced into the spacing and conduct the leakage to the container. The leakage sensor means is adapted to sense the receipt of leakage in the container. The logic unit is adapted to receive information from the leakage sensor means and determine the fourth significant change on basis thereof. By means of identifying the fourth significant change, the change to the fourth operational condition comprising a leakage of one of the first conduit and the second conduit can be detected by the logic unit of the hose arrangement.

According to an embodiment of the invention, the leakage sensor means is arranged at or in vicinity to the container.

According to an embodiment of the invention, the leakage sensor means comprises a liquid sensor that detects receipt of a liquid based on change in conductivity, capacitance, optical interface, and etcetera.

According to an embodiment of the invention, the leakage sensor means comprises a liquid sensor that detects receipt of a liquid based on change in conductivity, capacitance, optical interface, and etcetera.

According to an embodiment of the invention, the leakage sensor means comprises a float in the container, which float is adapted to be displaced between a first and a second position relating to no leakage and a leakage of the medium respectively.

According to an embodiment of the invention, the hose arrangement comprises signalling means for creating an alarm signal and the logic unit is adapted to control the signalling means in dependency of the change in operational condition of the hose unit.

According to an embodiment of the invention, the signalling means is adapted to create the alarm signal in form of one of a visual signal, an audible signal, and a vibration signal, or a combination thereof. The signalling means is for example an indication lamp, a buzzer, a vibration device, and etcetera.

The objects of the invention is further obtained by means of a method according to claim 1 1 for detecting an operational change of a hose unit. The method comprises the steps of:

- conducting a gas through the loop arrangement,

- receiving first information from the pressure sensor means and determining a first pressure or an entity dependent on the first pressure,

- receiving second information from the pressure sensor means and determining a second pressure or an entity dependent on the second pressure, and

- determining if a significant change in the pressure has occurred by comparing the first pressure and the second pressure, or the entity dependent of the first pressure and the second pressure. According to an embodiment of the invention, the method comprises:

- if a significant change has been determined, classifying a type of operational change of the hose unit on basis of the significant change, and

- on basis of the classified type of operational change, determining an operational condition of the hose unit.

According to an embodiment of the invention, the method comprises:

- classifying the significant change as a first significant change if the difference between the first pressure and the second pressure is positive and within a first range, or corresponding difference of the entity dependent of the first pressure and the second pressure, wherein the first significant change is related to a change to a first operational condition comprising a leakage of the second conduit.

According to an embodiment of the invention, the method comprises:

- classifying the significant change as a second significant change if the difference be-tween the first pressure and the second pressure is positive and within a second range, or corresponding difference of the entity dependent of the first pressure and the second pressure, wherein the second significant change is related to a change to a second operational condition comprising a separation of the first portion from the second portion of the hose unit.

According to an embodiment of the invention, the value of the first range is lower than the second range.

According to an embodiment of the invention, the method comprises:

- classifying the significant change as a third significant change if the difference between the first pressure and the second pressure is negative and within a third range, or corresponding difference of the entity dependent of the first pressure and the second pressure, wherein the third significant change is related to a change to a third operational condition comprising a leakage of the first conduit.

According to an embodiment of the invention, the method comprises:

- receiving information from the leakage sensor means, and

- classifying the significant change as a fourth significant change if the information from the leakage sensor means indicates certain degree leakage, wherein the fourth significant change is related to a change to a fourth operational condition comprising a leakage of one of the first conduit and the second conduit

The object of the invention is further obtained by means of use of a hose arrangement according to the invention.

Brief description of drawings In the following is described examples of preferred embodiments illustrated in the accompanying drawings, wherein :

Fig. 1 discloses a hose arrangement according to an embodiment of the invention, where a hose unit extends between a first and a second unit;

Fig. 2 discloses an example of the hose unit in fig. 1 ;

Fig. 3 discloses a cross section of an example of an intermediate portion of the hose unit in fig. 2;

Fig. 4a discloses a cross section of an example of a stress release unit of the hose unit in fig. 2, where the stress release unit is in an engaged state;

Fig. 4b discloses a cross section of the stress release unit in fig. 4a, where the stress release unit is in a disengaged state;

Fig. 5 discloses a schematic overview of the hose arrangement according to an embodiment of the invention;

Fig. 6 discloses a flowchart of a first embodiment of a method for detecting an operational change of a hose arrangement;

Fig. 7 discloses a flowchart of a second embodiment of a method for detecting an operational change of a hose arrangement; and

Fig. 8 discloses a flowchart on the steps of a determining a first, a second, a third and a fourth significant change that is related to a change to a respective first, second, third and fourth operational condition.

Detailed description of the invention

Fig. 1 discloses an overview of a hose arrangement 1 according to an embodiment of the invention. The hose arrangement 1 comprises an elongated hose unit 3 for transferring a flowable medium between a first unit 5 and a second unit 7. The hose unit 3 extends between the first unit 5 and the second unit 7. The hose unit 3 further comprises a stress release unit 10, such as a breakaway unit. In fig. 1 , the first unit 5 comprises an oil rig and the second unit 7 comprises a vessel.

The hose unit 3 comprises a first end portion 12 connected to the first unit 5 and a second end portion 14 connected to the second unit 7. In fig. 2, the embodiment of the hose unit 3 in fig. 1 is disclosed in further details, where a part of the hose unit 3 is stored on a storage drum 16.

Fig. 3 discloses a cross section at an example of an intermediate portion 18 of the hose unit 3 in fig. 2. The intermediate portion 18 of the hose unit 3 constitutes a main part of the extension of the hose unit 3. The hose unit 3 comprises a first conduit 20 adapted to guide the medium when the medium is transferred between the first unit 5 and the second unit 7. The hose unit 3 further comprises a second conduit 22 arranged around the first conduit 20 in order to protect the first conduit 20 from fracture due to abrasion or hits to its exterior surface. The second conduit 22 is further arranged so that a closed space 24 is formed between the first conduit 20 and the second conduit 22. The space 24 extends along the extension of the hose unit 3. Preferably, the first conduit 20 and the second conduit 22 comprise a uniform wall thickness along the extension of the hose unit 3. Accordingly, the space 24 is preferably uniformly arranged along the extension of the hose unit 3.

Referring to fig. 1 , 2, 4a and 4b, the hose unit 3 comprises a first hose portion 26 and a second hose portion 28 that are connected with each other by means of the stress release unit 10. The stress release unit 10 has the function to release the connection between the first hose portion 26 and the second hose portion 28 in the event that stress release unit 10 is subjected to a stress that exceeds a certain value. In fig. 4a the stress release unit 10 is in an engaged state, where the first hose portion 26 and the second hose portion 28 are connected. In fig. 4b the stress release unit 10 is in a disengaged state, where the first hose portion 26 and the second hose portion 28 are disconnected from each other.

An example of a cross section of the stress release unit 10 is disclosed in further detail in fig. 4a and 4b. The hose unit 3 comprises a further portion 30 of the space 24 that is adapted to receive the medium in case of a leakage of the first conduit 20. In particular, the further portion 30 of the space 24 is adapted to be arranged at a centre of mass M of the hose unit 3 in its fully extended configuration. Accordingly, when the hose unit 3 extends between the first unit 5 and the second unit 7, the further portion 30 of the space 24 will constitute the lowest point of the hose unit 3. In case of a leakage anywhere along the length of the hose unit 3, the medium will flow to the further portion 30 of the space 24.

The hose unit 3 further comprises a loop arrangement 40 comprising an inlet 42 to the space 24 and an outlet 44 from the space 24. The inlet 42 is adapted to guide a stream of pressurized gas, such as air, into the space 24. The outlet 44 is adapted to guide the gas and possible leakage of the medium out of the space 24.

The injection of the stream of gas is into the space 24 is adapted to pressurize the space 24 to a first pressure P1 . The outlet 44 is arranged extending to an outside that comprises a second pressure P2 that is lower than the first pressure P1 . Accordingly, due to the pressure difference between the space 24 and the outside, possible leakage of the medium will be transferred to the outside by means of the outlet 44 of the evacuation arrangement 40. Preferably, the second pressure P2 relates to the ambient air pressure and the first pressure P1 is set by the rate of injection of the stream of gas.

The inlet 42 comprises a third conduit 50 and the outlet 44 comprises a fourth conduit 52, see fig. 3. The fourth conduit 52 extends between a first opening 54 to the space 24 and a second opening 56 at the first end portion 12 of the hose unit 3. The third conduit 50 extends between a third opening 58 to the space 24 and a fourth opening 60 at the first end portion 12 of the hose unit 3.

Fig. 5 discloses a schematic overview of the hose arrangement 1 according to an embodiment of the invention. The hose arrangement 1 comprises a compressor device 70 for injecting compressed gas into that the loop arrangement 40. Preferably, the compressor device 70 is adapted to inject a stream of air into loop arrangement 40.

The hose arrangement 1 comprises pressure sensor means 80 that is adapted to sense the pressure of the gas that is being conducted in the loop arrangement 40. The pressure sensor means 80 is for example a piezoresistive pressure gauge, a capacitive pressure gauge, an electromagnetic pressure gauge, a piezoelectric pressure gauge, a potentiometric pressure gauge, a resonant pressure gauge, a thermal pressure gauge and an ionization pressure gauge. The pressure sensor means 80 is preferably arranged to sense the pressure of the gas after that the gas has been conducted through the inlet 42 and the outlet 44. Alternatively, the sensor means 80 comprises a gas volume sensor device arranged to sense the flow of the gas that is conducted through the space 24.

The hose arrangement 1 further comprises a logic unit 82 adapted to receive information from the pressure sensor means 80 and in dependency of said received information determine a significant change in the pressure or the flow of the gas, which significant change is related to a change in the operational condition of the hose unit 3.

On basis of the information from the pressure sensor means 80 or the flow sensor means, the logic unit 82 is adapted to determine a first significant change in the pressure. The first significant change is defined by a first decrease in the pressure of the gas or a first significant change in the gas flow. The significant change in the pressure or the gas flow indicates a change of the operation of the hose arrangement 1 from a normal operation to a first operational condition comprising a leakage of the second conduit 22.

On basis of the information from the pressure sensor means 80 or flow sensor means, the logic unit 82 is adapted to determine a second significant change in the pressure or the gas flow. The second significant change is defined by a second decrease in the pressure of the gas or the gas flow. The second significant change in the pressure or gas flow indicate a change of the operation of the hose arrangement 1 from a normal operation to a second operational condition comprising a separation of the first portion 12 from the second portion 14 of the hose unit 3. The second operational condition typical occurs when the hose unit 3 is subject to a stress exceeding a certain level in which the stress release unit 10 allows the first portion 12 from the second portion 14 of the hose unit 3 to be separated from each other. On basis of the information from the pressure sensor means 80 or flow sensor means, the logic unit 82 is adapted to determine a third significant change in the pressure or flow of the gas. The third significant change is defined by an increase in the pressure of the gas or flow of the gas. The third significant change in the pressure indicates a change of the operation of the hose arrangement 1 from a normal operation to a third operational condition comprising a leakage of the first conduit 20 in which the medium is allowed to be introduced into the spacing 24 of the hose unit 3.

A leakage entering the space is adapted to be evacuated from the hose unit 3 by means of the flow of the gas in the loop arrangement 40. The hose arrangement 1 further comprises a container 90 to which the leakage is adapted to be evacuated. Furthermore, hose arrangement 1 comprises leakage sensor means 92 for sensing a receipt of said leakage in the container 90. The logic unit 82 is adapted to receive information from the leakage sensor means 92 and determine a fourth significant change relating to receipt of the leakage in the container 90. The fourth significant change indicates a change of the operation of the hose arrangement 1 from a normal operation to a fourth operational condition comprising a leakage of one of the first conduit 20 and the second conduit 22.

The leakage sensor means 92 is for example a liquid sensor that detects receipt of a liquid based on change in conductivity, capacitance, optical interface, and etcetera. Alternatively, the leakage sensor means 92 comprises a float that is adapted to be displaced between a first and a second position relating to no leakage and a leakage of the medium respectively. According to an alternative embodiment, the evacuated medium is transferred back to its original source, such as a tank.

Preferably, the leakage sensor means 92 is configured to measure an amount of the medium and the logic unit 82 is adapted to determine an extent of the leakage of the medium based on information from the leakage sensor means 92 over time.

In the disclosed embodiment, the hose arrangement 1 further comprise a separation unit 94 in fluid communication with the outlet 44 and means for discharging medium that has been evacuated from the space 24. The separation unit 94 is adapted to separate the medium from the gas. In fig. 5, the hose arrangement 1 comprises a further container 96 and a discharge conduit 98 that is adapted to guide medium from the separation unit 94 to the further container 96 further in the event of extensive leakage that has been evacuated from the space 24.

The hose arrangement 1 further comprises signalling means 99 for creating an alarm signal and the logic unit is adapted to control the signalling means 99 in dependency of the change in operational condition of the hose unit 3. The signalling means 99 is for example adapted to create the alarm signal in form of one of a visual signal, an audible signal, and a vibration signal, or a combination thereof. The signalling means 99 is for example an indication lamp, a buzzer, a vibration device, and etcetera.

In fig. 6 a flowchart of a first embodiment of a method for detecting an operational change of a hose arrangement 1 is disclosed.

The method comprises, in a step 1 10, conducting a gas through the loop arrangement 40, and in a step 120, receiving first information from the pressure sensor means 80 and determining a first pressure or an entity dependent on the first pressure, such as the gas flow, and thereafter in a step 130, receiving second information from the pressure sensor means 80 or corresponding sensor means and determining a second pressure or corresponding second entity. The method thereafter comprises, in a step 140, determining if a significant change in the pressure exists by comparing the first pressure and the second pressure, or first entity and second entity dependent on the first pressure and the second pressure. The steps of 120-140 are preferably iterated over time of the operation of the hose arrangement 1 .

In fig. 7 a flowchart of a second embodiment of a method for detecting an operational change of a hose arrangement 1 is disclosed. The second embodiment in fig. 7 differs from the first embodiment in that the method further comprises the steps of, in a step 150, if a significant change has been determined, classifying a type of operational change of the hose unit 3 on basis of the significant change. The method further comprises, in a step 160, on basis of the classified type of operational change, determining a change of the operational condition of the hose arrangement 1 .

Fig. 8 discloses further details on step 150 comprising the steps of a determining a first, a second, a third and a fourth significant change that is related to a change to a respective first, second, third and fourth operational condition. It shall be understood that the invention according to the embodiment in fig. 7 comprises one or any combination of the steps 152, 154, 156 and 1 58 to be described in the following.

The method comprises, in a step 152, classifying the significant change as a first significant change if the difference between the first pressure and the second pressure is positive and within a first range, or alternative based on corresponding first entity and second entity dependent on the first pressure and second pressure. The first significant change is related to a change to a first operational condition comprising a leakage of the second conduit 22.

The method further comprises, in a step 154, classifying the significant change as a second significant change if the difference between the first pressure and the second pressure is positive and within a second range, or alternative based on corresponding first entity and second entity. The second significant change is related to a change to a second operational condition comprising a separation of the first portion 12 from the second portion 14 of the hose unit 3.

The method further comprises, in a step 156, classifying the operational change as a third significant change if the difference between the first pressure and the second pressure is negative and within a third range, or alternative based on corresponding first entity and second entity dependent on the first pressure and second pressure. The third significant change is related to a change to a third operational condition comprising a leakage of the first conduit 20.

The method further comprises, in a step 158a, receiving information from the leakage sensor means 92, and in a step 158b, determining if a fourth significant change relating to if a leakage is present. The method comprises, in a step 158c, if a fourth significant change has been determined, classifying the operational change as a fourth operational condition comprising a leakage of one of the first conduit 20 and the second conduit 22.

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 embodiments without departing from the scope of the appended claims. In the claims, any reference 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. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.