An articulated screw rotor and sensor apparatus incorporating same

Abstract

An articulated screw rotor fluid pipe insert comprising at least two screw rotor segments connected in an end-to-end configuration by an articulated joint, each screw rotor segment comprising at least one helical flight about a central shaft.

Description

[0001] AN ARTICULATED SCREW ROTOR AND SENSOR APPARATUS INCORPORATING SAME

[0002] Technical Field of the Invention

[0003] The present invention relates to monitoring of fluid pipes. In particular, the invention relates to monitoring of the properties of fluid with a fluid pipe using a sensing fibre. The present invention further relates to an apparatus and a method for monitoring fluid flow and / or pressure in a fluid pipe as well as a network comprising one or more pipes monitored using the apparatus or the method of the present invention.

[0004] Background to the Invention

[0005] Many modem services rely upon a network of pipes to carry or distribute fluids. Examples include fresh water, waste water and sewage, and fuels such as oil or gas. It is common to monitor the operation of the network and the condition of pipes. In this manner, blockages, leaks or other issues can be identified and scheduled for repair.

[0006] Fibre sensing is a technique that uses the changes in the properties of a fibre, or sensing fibre, to make measurements of the fibre’s environment, such as pressure, temperature, strain, and vibrations (acoustics). As fibres can be made relatively cheaply, they can be ran over long distances and then used to make measurements at different points along their length. This makes them very useful for data collection activities where power or access is limited, such as along buried pipes or in remote areas. This can assist in the monitoring of pipe networks such as fresh water, waste water and sewage, and fuels such as oil or gas. It is common to monitor the operation of the network and the condition of pipes. In this manner, blockages, leaks or other issues can be identified and scheduled for repair.

[0007] In order to make measurements, light pulses are coupled into a sensing fibre. The external environment and conditions of the sensing fibre affect backscattered light pulses generated as the light pulses travel through the sensing fibre. These backscattered pulses can then be detected and used to make a measurement of a property of interest at different points along the sensing fibre. There are a number of different techniques that can be employed such as distributed acoustic sensing (DAS) (or distributed vibration sensing (DVS)), distributed strain sensing (DSS) and distributed temperature sensing (DTS). This technique is also further described in WO2019 / 166809A1.

[0008] A current limitation of widespread monitoring systems is the cost of deployment of highly distributed sensors. This can involve significant capital and labour costs. Additionally, it can be difficult to arrange an adequate power supply for a sensor to operate. At present these are very dispersed and infrequently located, meaning the full realisation of the benefits of highly distributed sensors cannot be achieved.

[0009] Another limitation is that backhaul of data on a real time basis is problematic, finite battery capacity means that sensor data is often only transmitted once per day (typically via radio, where power consumption is high), or if land lines are used this can be at very high operational (circuit rental) cost.

[0010] It is therefore an object of embodiments of the present invention to at least partially address the above issues.

[0011] Summary of the Invention

[0012] According to one broad aspect of the present invention, there is provided an articulated screw rotor fluid pipe insert comprising at least two screw rotor segments connected in an end-to-end configuration by an articulated connection, each screw rotor segment comprising at least one helical flight about a central shaft.

[0013] According to a further aspect of the present invention, there is provided an articulated screw rotor fluid pipe insert for a fluid pipe having an internal diameter, Dpipe, the articulated screw rotor fluid pipe insert comprising at least two screw rotor segments connected in an end-to-end configuration by an articulated connection, each screw rotor segment comprising at least one helical flight about a central shaft wherein a length of each screw rotor segment is no greater than Dpipe.

[0014] Providing an articulated screw rotor fluid pipe insert as defined allows a rotor of a length which is greater than an internal diameter of a fluid pipe, to be inserted into and removed from a fluid pipe.

[0015] According to another aspect of the present invention, there is provided a sensing apparatus for monitoring a fluid pipe, the apparatus comprising: at least one sensing fibre provided within the pipe; a light emitter for introducing light pulses with particular characteristics into the fibre; a light detector module configured to detect backscattering of the light pulses from the sensing fibre in multiple different sensing modes and output a detector output signal in response thereto; at least one an articulated screw rotor fluid pipe insert configured to generate characteristic acoustic events at a rate indicative of fluid flow velocity; and a fluid flow processing unit configured to process the detector output signal to extract a component of the detector output signal derived from said characteristic acoustic events from the detector output signal so as to monitor flow velocity.

[0016] According to yet another aspect of the present invention, there is provided a power generation and flow sensing apparatus for a fluid pipe, the apparatus comprising: a) an articulated screw rotor fluid pipe insert configured to rotate in response to fluid flow within the fluid pipe; b) A rotation rate detector configured to detect the rotation rate of the an articulated screw rotor fluid pipe insert and output a signal indicative thereof; c) A generator module driven by the articulated screw rotor fluid pipe insert and comprising a rotator element and a stator element, wherein relative movement between the rotator element and stator element against electromagnetic resistance generates an output electrical current; and d) A switching module configured to switch the apparatus between an active mode where the flow rotor is coupled to the generator module and a passive mode where the flow rotor is not coupled to the generator module.

[0017] The articulated screw rotor fluid pipe insert may be that of either of the aspects described herein. In the context of the present application, the term ‘fluid’ in relation to a fluid pipe or conduit may refer to any material, liquid or gaseous, including fuels such as oil or gas or associated distillates, additionally in industrial uses which may include mining and similar, the invention may more specifically refer to a primarily water-based fluid, such as potable water, pre-treatment water, wastewater or water-based slurries.

[0018] Similarly, in the context of the present application, the term ‘pipe’ or ‘conduit’ may refer to any fluid conduit used to convey a fluid (gas, liquid or a mixture including a slurry) between two points, spaced apart at or below local ground level. In particular, the ‘pipe’ or ‘conduit’ may traverse at a relatively regular displacement from local ground level, without requiring the ‘pipe’ or ‘conduit’ to be horizontal. Thus, the terms “pipe” and “fluid pipe” may be used interchangeably.

[0019] The fluid pipe in which the sensing arrangement is provided may be a single unbranched length of pipe. In such embodiments, the sensing fibre may run along the pipe from one end to the other. In other such embodiments the sensing cable may run in a loop from one end of the pipe to be monitored to the other end and back again.

[0020] The fluid pipe in which the sensing arrangement is provided may comprise a branched network of pipes or part of a branched network of pipes. In such embodiments the sensing cable may run in a loop from an entry point to the far end of each branch in turn.

[0021] The branched network may be any suitable branched network of fluid pipes. In one example, the branched network is a district metered area of a water supply network.

[0022] In some embodiments, a sensing apparatus may be adapted to monitor multiple pipes under test. In such embodiments, each pipe to be monitored may be a single unbranched length of pipe or each pipe to be monitored may be branched network of pipes or part of a branched network of pipes. In further such embodiments, some pipes to be monitored may be single unbranched lengths of pipe and other pipes to be monitored may be branched networks of pipes or parts of branched networks of pipes.

[0023] In one form, the articulated screw rotor fluid pipe insert is located in the fluid flow for rotation according to the fluid flow. In some embodiments, more than one articulated screw rotor fluid pipe insert may be provided in a fluid pipe. In some such embodiments, a single sensing fibre may be provided for each articulated screw rotor fluid pipe insert. In other embodiments, a single sensing fibre element may be provided for multiple articulated screw rotor fluid pipe inserts.

[0024] The articulated screw rotor fluid pipe insert may be mounted for rotation about an axis which is parallel to the direction of fluid flow in the fluid pipe.

[0025] The articulated screw rotor fluid pipe insert may be installed through an access opening in a pipe. Such access openings are often located on an upper side of a pipe favouring a vertical entry and the articulation of the articulated screw rotor fluid pipe insert may then allow the articulated screw rotor fluid pipe insert to orient substantially parallel to the fluid flow direction. In concert with lower flow velocities, for instance in water pipes, this may be advantageous as the diameter of a helical flight on the articulated screw rotor fluid pipe insert may be limited to the diameter of an access opening in the pipe (where such may be in the range 100mm to 200mm), but the length of the articulated screw rotor fluid pipe insert may be greater than the internal diameter of the fluid pipe.

[0026] The articulated screw rotor fluid pipe insert may be downstream of any nearby in-line valves in the fluid pipe.

[0027] The articulated screw rotor fluid pipe insert may be fixed in position within the fluid pipe such that the fluid flow moving past the helical articulated screw rotor fluid pipe insert drives rotation of the articulated screw rotor fluid pipe insert.

[0028] Any number of segments may be used in the articulated screw rotor fluid pipe insert. The number of segments used may primarily be determined according to the length of the segments, the length of any connection arrangement provided between the segments and a required overall length of the articulated screw rotor fluid pipe insert.

[0029] The overall length of the articulated screw rotor fluid pipe insert may be varied according to power generation requirements. A longer articulated screw rotor fluid pipe insert may increase power generation for example but it may be more difficult to start of rotation, particularly in a low flow velocity environment. The overall length of the articulated screw rotor fluid pipe insert may be longer than the inner diameter of the fluid pipe.

[0030] The dimensions of the articulated screw rotor fluid pipe insert may be determined according to power generation requirements. In one form, the power generation possible using an articulated screw rotor fluid pipe insert may be a function of the helical flight dimensions (pitch, outer diameter and flight height (the difference between the outer diameter of the central shaft and the outer diameter of the helical flight)), the central shaft dimensions and / or overall length of the articulated screw rotor fluid pipe insert. In an embodiment, the outer diameter of the helical flight may be defined by the inner diameter of an entry port on the fluid pipe through which the articulated screw rotor fluid pipe insert is introduced into the fluid pipe.

[0031] Each screw rotor segment may have any number of helical flights on the central shaft. One helical flight may be used on each screw rotor segment. The helical flights of the segments used in an articulated screw rotor fluid pipe insert preferably cooperate in driving rotation of the articulated screw rotor fluid pipe insert in the fluid flow. The helical flights of the segments used in an articulated screw rotor fluid pipe insert may be aligned to maximise rotation under the fluid flow.

[0032] The articulated screw rotor fluid pipe insert may be formed from any suitable material including but not limited to metals such as stainless steel or polymers. Use of such commonly available materials can ensure the cost of the articulated screw rotor fluid pipe insert is minimised. The articulated screw rotor fluid pipe insert material can be selected so that the rotor has a relatively low mass. This can assist start of rotation in a low flow velocity environment.

[0033] In another form, the articulated screw rotor fluid pipe insert may be or comprise an articulated Archimedes screw rotor with at least two Archimedes screw rotor segments or portions articulated relative to one another.

[0034] The articulated screw rotor fluid pipe insert may extend along a fluid pipe length forming a horizontal axis rotor.

[0035] An end segment may be provided for the free end of the articulated screw rotor fluid pipe insert. The end segment may be provided with an articulated connection at one end only. The articulated connection may be provided on the end of the central shaft, allowing articulated connection to an adjacent segment and / or to a connection arrangement. The central shaft may have a blind or closed end at the opposite end of the end segment to the articulated connection.

[0036] One or more intermediate segments may be provided between the end segment and the mount for the articulated screw rotor fluid pipe insert. Each intermediate segment may be provided with an articulated connection at both ends. The articulated connections may be provided on the end of the central shaft, allowing articulated connection to an adjacent segment and / or to a connection arrangement, and / or to the mount.

[0037] As explained, the segments may connect directly together, or a connection arrangement may be provided between adjacent segments to connect them together. The provision of a connection arrangement may increase the distance between the helical flights of adjacent segments, allowing the outer diameter of the helical flights to be maximised but allowing increased articulation, and / or clearance between the helical flights of adjacent segments.

[0038] The articulated connection between adjacent segments and / or the connection arrangements may be any type which allow the segments and / or the connection arrangements to hinge relative to one another whilst connecting the segments and / or the connection arrangements for rotary motion together. The articulated connection may comprise a universal joint (single or multi-section universal joint), a constant velocity joint or any other means. As an example, a spring may be provided as the connection or as a part of the connection as this may allow the segments to hinge relative to one another whilst providing for rotary motion together.

[0039] Where provided, a connection arrangement may comprise a length of shaft with an articulated connection at both ends. As mentioned above, the connection arrangement may increase the distance between adjacent segments to provide increased angular clearance during insertion and removal.

[0040] Each segment may include at least one helical flight about a central shaft. The central shaft may be elongate. The central shaft may be hollow. The ends of the central shaft may be sealed to prevent fluid entering the central shaft. Provision of a hollow central shaft may provide buoyancy to at least partially counteract the mass of the helical flight and any connection / connection arrangement.

[0041] Each segment may be neutrally buoyant. The fluid flow in the fluid pipe may act to centralise the articulated screw rotor fluid pipe insert within the fluid pipe and / or stabilise the articulated screw rotor fluid pipe insert during rotation.

[0042] The at least one helical flight may be solid. The at least one helical flight may have any slope, pitch, height and / or outer diameter. The design parameters of the at least one helical flight may be optimised to balance the weight of the segment (and / or the articulated screw rotor fluid pipe insert overall) whilst maximising the conversion of the fluid flow in the fluid pipe into rotation of the articulated screw rotor fluid pipe insert.

[0043] A mount may be provided, connected to one end of the articulated screw rotor fluid pipe insert to mount the articulated screw rotor fluid pipe insert within the fluid pipe. The mount may also be used for insertion and removal. The mount may be an elongate shaft or similar. The mount may extend into or through a fluid pipe entry / exit fitting. The mount may transmit rotation of the articulated screw rotor fluid pipe insert outside the fluid pipe if desired. For example, a pressure seal may be provided to seal about the mount. A pressure seal may allow live insertion and removal of the articulated screw rotor fluid pipe insert whilst fluid is flowing in the fluid pipe.

[0044] A number of connection arrangements may be provided between the mount and the first segment of the articulated screw rotor fluid pipe insert. This may allow greater clearance or articulation at entry / exit.

[0045] The articulated connection and / or connection arrangement may further comprise a damping link. The damping link may be provided to minimise or buffer any relative movement (apart from rotation) between adjacent segments and / or connection arrangements. One or more segments in the articulated screw rotor fluid pipe insert may experience ‘fluttering’ dependent upon the fluid flow characteristics within the fluid pipe, for example in turbulent or variable flow conditions. This fluttering is undesirable as it may detract from or disrupt rotation of the articulated screw rotor fluid pipe insert. The provision of a damping link may dampen any such undesirable movement. In one form, the damping link may be or include an elastomeric body or sleeve, but any appropriate damping link may be provided, for example, including but not limited to resilient members, springs or the like.

[0046] A launch tube may be provided to introduce to and / or remove the articulated screw rotor fluid pipe insert from the fluid pipe. The launch tube may attach to a fluid pipe entry / exit fitting. The launch tube may remain attached during operation of the articulated screw rotor fluid pipe insert. In one embodiment, a flange fitting may be provided on the launch tube corresponding to the flange fitting on the pipe entry / exit fitting. The launch tube may be dimensioned to accommodate the outer diameter of the articulated screw rotor fluid pipe insert relatively closely. The launch tube may have an inner diameter to correspond to the inner diameter of the pipe entry / exit fitting.

[0047] The articulated screw rotor fluid pipe insert may remain in the launch tube when removed from the fluid pipe to protect the helical flights of the segments.

[0048] The sensor apparatus may additionally comprise a static component, wherein interaction between the articulated screw rotor fluid pipe insert and the static component generates the characteristic acoustic event.

[0049] As mentioned above, the characteristic acoustic event may be detected by the sensing fibre.

[0050] The interaction between the articulated screw rotor fluid pipe insert and the static component may occur at a particular rotor orientation. The interaction between the articulated screw rotor fluid pipe insert and the static component may generate the characteristic acoustic event only when the articulated screw rotor fluid pipe insert is rotating. For example, the interaction may only occur once the articulated screw rotor fluid pipe insert is rotating at a substantially steady state in the fluid flow and not for example, at startup.

[0051] The static component may be or may project from a mount upon which the articulated screw rotor fluid pipe insert is provided. In suitable embodiments, the static component may be a tube through which the at least one sensing fibre and / or sensing cable may enter or exit the fluid pipe. The interaction between the articulated screw rotor fluid pipe insert and the static component may be direct or may be indirect.

[0052] The detector output signal may comprise multiple channels, each channel corresponding to a particular location along the sensing fibre. Each channel may be defined by reference to the round-trip time for backscattered pulses from the particular location. Neighbouring channels may be defined by the minimum resolvable time interval between backscattered pulses from neighbouring sensing fibre locations. Accordingly, each articulated screw rotor fluid pipe insert location can correspond to a particular channel within the detector output signal. In such embodiments, the fluid flow processing unit may be configured to extract the component of the detector output signal derived from said characteristic acoustic events by reference to a particular channel within the detector output signal. The referenced channel may correspond to the location of a particular articulated screw rotor fluid pipe insert along the length of the sensing fibre. Accordingly, if the location of each articulated screw rotor fluid pipe insert along the length of the sensing fibre is known the component of the detector output signal derived from said characteristic acoustic events can be extracted by reference to the corresponding channel within the detector output signal. In embodiments with multiple flow velocity sensor elements, there may be multiple referenced channels. In such cases, each channel may correspond to the location of an articulated screw rotor fluid pipe insert.

[0053] The fluid flow processing unit may be configured to identify the characteristic acoustic events within the extracted component of the detector output signal. This may be achieved by filtering the extracted component to an acoustic frequency range corresponding to the characteristic acoustic events.

[0054] The fluid flow processing unit may be configured to calculate a fluid flow velocity from the identified the characteristic acoustic events. This may be achieved by determining the repetition rate of the characteristic acoustic events. This may further involve applying a conversion factor or series of conversion factors to the determined repetition rate to thereby calculate the fluid flow velocity. Accordingly, suitable analysis of the sensing fibre can enable calculation of a flow velocity in the fluid pipe at the sensor location, without requiring a local power source for the sensor. The sensing apparatus may further comprise a base module comprising the light emitter and the light detector. The base module may comprise a coupling assembly configured to remotely couple light pulses into the sensing fibre and backscattered light pulses out of the sensing fibre.

[0055] The sensing apparatus may comprise an analyser to analyse the detector output signal. In some embodiments, the analyser may be provided within the base module. In other embodiments, the analyser may be located remotely from the base module. The analyser may interrogate a specific location of the sensing apparatus. The fluid flow processing unit may be integrated into the analyser or may be provided separately to the analyser.

[0056] The at least one sensing fibre may be provided as a part of a sensing cable extending with or within the fluid pipe.

[0057] The pipe fitting may provide an entry / exit point on the fluid pipe for the sensing fibre. The pipe fitting may provide an entry / exit point on the fluid pipe for the tube of the sensor. The pipe fitting may provide entry / exit points on the fluid pipe for the sensing fibre and the tubes of two sensors, each sensor associated with one of the two sensing locations. Thus, the pipe fitting enables simple and efficient connection to the inside of the pipe. The entry / exit points may be standard access openings on the fluid pipe or may be dedicated openings formed for mounting the sensing fibre and / or the tube of the sensor.

[0058] The pipe fitting may comprise a semi-rigid tubular arrangement configured to be inserted into the fluid pipe. The tubular arrangement may be configured to resist a fluid flow within the pipe. The sensing fibre may be provided inside the tubular arrangement. The tubular arrangement may be configured to control placement of the sensing fibre within the fluid pipe. Thus, the sensing fibre position in the pipe is better controlled.

[0059] In other embodiments, the pipe to be monitored may provide entry / exit points and / or tubular arrangements as described above. The pipe fitting may be configured to mount the sensing fibre and one or more sensing locations (e.g. two sensing locations) to an outside of the pipe to be monitored. Thus, the pipe fitting can be simply and easily mountable to the pipe.

[0060] In another aspect of the present invention, there is provided a fluid distribution system comprising one or more fluid pipes and at least one sensing apparatus according to the present invention provided at one or more points within the fluid distribution system; and a system controller wherein each sensing apparatus is connected to the system controller.

[0061] In this manner, the system controller can monitor fluid flow at multiple points within a fluid distribution system.

[0062] The sensing fibre may be provided at least partially inside the pipe. This enables the sensing fibre to conveniently travel between sensing locations and a base module without needing to separately lay or otherwise install the sensing fibre.

[0063] The articulated screw rotor fluid pipe insert may be a multipurpose rotor, provided as a part of a flow sensing apparatus to function as both a flow velocity sensor element associated with the fluid flow within the fluid pipe and having a secondary, power generation function.

[0064] The articulated screw rotor fluid pipe insert may be provided as a power generator only.

[0065] The articulated screw rotor fluid pipe insert may be mounted for rotation relative to at least one flow velocity sensor element, such as a sensing fibre which may function as the rotation rate detector and / or a tube within which the at least one flow velocity sensor element is mounted relative to the fluid pipe.

[0066] Where provided as a part of a flow sensing apparatus and having a secondary, power generation function, the apparatus may be switchable. An articulated screw rotor fluid pipe insert coupled to a generator module to produce electrical current may increase the load on the articulated screw rotor fluid pipe insert which in turn may decrease the accuracy of the articulated screw rotor fluid pipe insert if used at the same time as part of a flow sensor apparatus, because the increased load on the articulated screw rotor fluid pipe insert may adversely affect the relationship between the fluid flow velocity and the rotational speed of the articulated screw rotor fluid pipe insert. The articulated screw rotor fluid pipe insert may be provided in a passive, sensing mode (decoupled from the generator) and be switched to an active, power generation mode by coupling to the generator for periods of time to generate power as required. The switching may preferably be automatic. The switching may be achieved by means of a clutch mechanism or by the disabling of electrical power generation.

[0067] When in the active mode, the rotation rate detector may be deactivated or alternatively may continue to operate, but with the signal identified as being during the active mode. Any fluid flow processing unit may be configured to process the detector output signal to extract a component of the detector output signal derived from the signal indicative of rotation rate of the articulated screw rotor fluid pipe insert from the detector output signal when the apparatus is in the passive mode.

[0068] The generator module may only operate when the apparatus is in the active mode.

[0069] A controller may be provided (in situ or remote) to control the switching according to power required. The controller may switch the apparatus between the active mode and the passive mode according to usage. The controller may switch the apparatus between the active mode and the passive mode according to a duty cycle. The duty cycle may prioritize the active mode over the passive mode. This may mean that the apparatus provides fluid flow information for as long as possible in the active mode to generate electrical current before switching to the active mode and remains in the passive mode for the shortest time possible to measure flow. This can beneficially ensure that the generated electrical power matches or exceeds any power requirements of the present apparatus. Furthermore, intermittent flow sensing may suffice for many monitoring purposes.

[0070] For example, the controller may switch to the passive mode for less than 50% of operating time, less than 40% of operating time, or less than 30% of operating time or less than 20% of operating time or less than 10% of operating time or less than 5% of operating time or less than 2% of operating time.

[0071] The duty cycle may be varied by the controller as required, for example, if there is above normal power usage. The generator module may provide the output electrical current directly to component(s) of the apparatus requiring power and / or to a storage device such as a battery. Providing excess electrical current to a storage device may allow the controller to reduce the active mode as the apparatus may be supplied with electrical power from the storage device. Additionally or alternatively, the storage device may be connected to one or more other sensors or devices for the purpose of providing power to said other sensors or devices.

[0072] The generator module and / or controller may be provided in an all-in-one configuration with the apparatus allowing for simpler installation of the apparatus relative to a fluid pipe.

[0073] The generator module may be located relative to the mounting shaft of the articulated screw rotor fluid pipe insert which mounts the articulated screw rotor fluid pipe insert within the fluid pipe. The generator module may be located within the fluid pipe or outside the fluid pipe or within the launch tube.

[0074] The controller need not be located at the location of the apparatus and may be remotely located. A central controller may control more than one apparatus. A communication pathway may be provided between the apparatus and a controller which is remotely located.

[0075] The rotation rate detector may be a contact detector arrangement to detect rotation rate through physical contact with the articulated screw rotor fluid pipe insert during rotation.

[0076] In another embodiment, the rotation rate detector may comprise a non-contact detector arrangement which may include light reflection by means of an LED or laser source, or by means of an ultrasonic sonar system, with the light or sonar signal powered by electrical current generated by the generator module. In other embodiments, the rotation rate detector may comprise a semiconductor or similar magnetic field detector such as a Hall Effect sensor, or the like.

[0077] In some embodiments, the rotation rate detector may comprise a voltage meter for detecting voltage generated by rotation on the unloaded generator module in the passive mode. Such a voltage developed would be directly proportional to rotational velocity of the articulated screw rotor fluid pipe insert. In particular embodiments, the voltage meter may be a high impedance / high resistance voltage meter. In such cases, if the impedance / resistance is sufficiently high (e.g. > lOkohm) to prevent significant current flow in the generator, then there would be substantially no slowing of rotation rate due to power generation. Accordingly, the generated voltage would be directly related to the free rotation rate of the articulated screw rotor fluid pipe insert and hence the fluid flow rate.

[0078] An acoustic event generator may be provided, associated with the at least one sensing fibre. The acoustic event generator may be a vibration unit, vibrator, sounder or the like.

[0079] The acoustic event generator may be configured to output characteristic acoustic events at a rate indicative of the fluid flow rate determined by a non-contact detector. These characteristic acoustic events can then be detected, extracted and / or processed using the sensing fibre in a corresponding manner to direct interactions.

[0080] In other embodiments, an acoustic event generator may be configured to output acoustic signals whereby the acoustic frequency of the acoustic signals is indicative of non-contact detector output signals. Typically, such acoustic signals may be in a range of between 100Hz to 1kHz. Where a voltage meter is provided, the acoustic signals may be generated in response to a voltage controller oscillator connected to the voltage meter. This can thereby directly scale the voltage meter output to an acoustic frequency output.

[0081] In other embodiments, the acoustic event generator may be configured to output acoustic signals indicative of non-contact detector output signals. Such acoustic signals can be detected and extracted using the sensing fibre as described above. Subsequently, the acoustic signals may be decoded to recreate the non-contact detector output signals. This can thereby facilitate the non-contact detector output signals being transmitted over the sensing fibre for processing at a remote location.

[0082] With the provision of a generator module to produce output electrical current, this allows one or more secondary sensors which utilise electrical current to operate. Any type of secondary sensor may be provided. The secondary sensor may have any suitable configuration to sense a property to be measured. For example, a fluid flow speed, fluid flow direction, fluid temperature and / or fluid pressure sensor could be provided. The secondary sensor may be associated with an acoustic event generator to associate with the at least one sensing fibre. The fluid flow processing unit may be configured to process the detector output signal to extract a component of the detector output signal derived from any one or more secondary sensor from the detector output signal so as to monitor a desired property of the fluid in the fluid pipe.

[0083] The output of any secondary sensor may be monitored outside of the fluid pipe.

[0084] The output of any secondary sensor may be converted into a sensor output such as a suitable pulsed frequency. Such a pulsed frequency may be preferentially in the range 250Hz to 2kHz.

[0085] Any one or more sensors may be powered up and down as required. This may allow a reduction in overall power consumption but still provide quasi real-time sensor readings. However, the provision of an articulated screw rotor fluid pipe insert or similar to generate electrical current based on fluid flow, may allow any secondary sensing apparatus to operate at all times, providing true real-time sensor readings.

[0086] The skilled person will appreciate that except where mutually exclusive, a feature described in relation to any one of the aspects, methods, examples or embodiments described herein may be applied to any other method, aspect, example, embodiment or feature. Further, the description of any aspect, method, example or feature may form part of or the entirety of an embodiment of the invention as defined by the claims. Any of the examples described herein may be an example which embodies the invention defined by the claims and thus an embodiment of the invention.

[0087] Detailed Description of the Invention

[0088] In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0089] Figure 1 is a side elevation view of an articulated screw rotor fluid pipe insert of an embodiment in the operating position within a fluid pipe. Figure 2 is a side elevation view of the configuration illustrated in Figure 1 with showing insertion / removal of the articulated screw rotor fluid pipe insert using a launch tube.

[0090] Figure 3 is a side elevation view of an articulated screw rotor fluid pipe insert of another embodiment in the operating position within a fluid pipe.

[0091] Figure 4 is a side elevation view of the configuration illustrated in Figure 2 with a throughbore valve for live insertion / removal of the articulated screw rotor fluid pipe insert.

[0092] Figure 5 is a schematic block diagram of a sensing apparatus for monitoring the condition of a fluid pipe as used in the present invention.

[0093] Figure 6 a schematic block diagram of a processing arrangement, according to the prior art, for the sensing apparatus of figure 17.

[0094] Figure 7 is a schematic block diagram of the control architecture of for switching the flow rotor between active and passive modes.

[0095] Figure 8 is a schematic diagram of a switching module arrangement according to an embodiment.

[0096] An articulated screw rotor fluid pipe insert 3 for a fluid pipe 2 having an internal diameter, Dpipe, is illustrated in Figures 1 to 4.

[0097] The articulated screw rotor fluid pipe insert 3 illustrated comprises four screw rotor segments (three intermediate rotor segments 300 and one end rotor segment 301) connected in an end-to-end configuration by articulated connection arangements 307. Each screw rotor segment (300, 301) illustrated comprises a helical flight 302 about a central shaft 303. As illustrated, the length 304 of each screw rotor segment (300, 301) is no greater than Dpipe.

[0098] As shown, the articulated screw rotor fluid pipe insert 3 may located in the fluid flow for rotation according to the fluid flow. The fluid flow direction is shown by 305. The fluid flows past the articulated screw rotor fluid pipe insert 3 which rotates due to the helical flights 302. The articulated screw rotor fluid pipe insert 3 is mounted for rotation about an axis which is parallel to the direction of fluid flow 305 in the fluid pipe 1 as shown in Figure 1 which shows the operation position.

[0099] The articulated screw rotor fluid pipe insert 3 may be installed and / or removed through an access opening in a pipe entry / exit fitting 306 on the fluid pipe 2 as shown in Figure 2. Such access openings are often located on an upper side of a pipe 2 as shown in Figure 2, favouring a vertical entry. The articulation of the articulated screw rotor fluid pipe insert 3 may then allow the articulated screw rotor fluid pipe insert 3 to orient substantially parallel to the fluid flow direction 305. In concert with lower flow velocities, for instance in water pipes, this may be advantageous as the diameter of a helical flight 302 on the articulated screw rotor fluid pipe insert 3 may be limited to the diameter of an access opening in the pipe (where such may be in the range 100mm to 200mm), but the length of the articulated screw rotor fluid pipe insert may be greater than the internal diameter of the fluid pipe, Dpipe.

[0100] The articulated screw rotor fluid pipe insert 3 may be fixed in position within the fluid pipe 2 such that the fluid flow moving past the helical articulated screw rotor fluid pipe insert 3 drives rotation of the articulated screw rotor fluid pipe insert 3. Although the articulated screw rotor fluid pipe insert 3 may be used as a part of a fluid flow velocity apparatus, the articulated screw rotor fluid pipe insert 3 of the illustrated embodiments is associated with an altemator / generator 230 for power generation based on the rotation driven by the fluid flow.

[0101] In Figure 1, the alternator / generator 230 for power generation is located outside the fluid pipe 2, whereas in Figure 3, the alternator / generator 230 for power generation is located within the fluid pipe 2 between the mounting rod 308 and the articulated screw rotor fluid pipe insert 3.

[0102] Although four segments 300, 301 are shown in the Figures, any number of segments may be used in the articulated screw rotor fluid pipe insert 3. The number of segments 300, 301 used may primarily be determined according to the length of the segments, the length of any connection arrangement 307 between the segments 300, 301 and the required overall length of the articulated screw rotor fluid pipe insert 3. The overall length of the articulated screw rotor fluid pipe insert 3 may be varied according to power generation requirements. A longer articulated screw rotor fluid pipe insert 3 may assist start of rotation in a low flow velocity environment. As shown, the overall length of the articulated screw rotor fluid pipe insert 3 may be longer than the inner diameter of the fluid pipe, Dpipe.

[0103] Without wishing to be limited by theory, the power generation possible using an articulated screw rotor fluid pipe insert 3 may be a function of the helical flight 302 dimensions (pitch, outer diameter and flight height (the difference between the outer diameter of the central shaft 303 and the outer diameter of the helical flight 302)), the central shaft 303 dimensions and the length of the articulated screw rotor fluid pipe insert 3. In use, the outer diameter of the helical flight 302 may be limited by the inner diameter of an entry port 306 on the fluid pipe 2 through which the articulated screw rotor fluid pipe insert 3 is introduced into the fluid pipe.

[0104] Each screw rotor segment 300, 301 may have any number of helical flights on the central shaft but a single helical flight is used on each screw rotor segment 300, 301 of the illustrated embodiment. The helical flights 302 of the segments 300, 301 used in the articulated screw rotor fluid pipe insert 3 preferably cooperate in driving rotation of the articulated screw rotor fluid pipe insert 3 in the fluid flow 305. The helical flights 302 of the segments 300, 301 used in an articulated screw rotor fluid pipe insert 3 may be aligned to maximise rotation under the fluid flow.

[0105] The articulated screw rotor fluid pipe insert may be formed from any suitable material including but not limited to metals such as stainless steel or polymers. Use of such commonly available materials can ensure the cost of the articulated screw rotor fluid pipe insert is minimised. The articulated screw rotor fluid pipe insert material can be selected so that the rotor has a relatively low mass and / or buoyancy. This can assist start of rotation in a low flow velocity environment.

[0106] In the illustrated form, the articulated screw rotor fluid pipe insert 3 is configured as an articulated Archimedes screw rotor with four Archimedes screw rotor segments articulated relative to one another. As shown, the end segment 301 may be provided at the free end of the articulated screw rotor fluid pipe insert 3. The end segment 301 shown is provided with an articulated connection at one end only. The articulated connection is provided on the end of the central shaft 303 of the end segment 301, allowing connection to a connection arrangement 307. The central shaft 303 shown in the Figures includes a blind or closed free end at the opposite end of the end segment 301 to the connection arrangement 307.

[0107] The intermediate segments 300 shown are provided between the end segment 301 and the mounting rod 308 for the articulated screw rotor fluid pipe insert 3. Each intermediate segment 300 has articulated connection is provided at both ends, on the end of the central shaft 303 of the intermediate segment 300, allowing connection to a connection arrangement 307.

[0108] The provision of a connection arrangement 307 may increase the distance between the helical flights 302 of adjacent segments 300, 301 as shown in Figure 2, allowing the outer diameter of the helical flights 302 to be maximised but allowing increased articulation, and / or clearance between the helical flights 302 of adjacent segments.

[0109] The articulated connection between adjacent segments and the connection arrangements 307 shown may be any type which allow the segments 300, 301 and / or the connection arrangements 307 to hinge relative to one another whilst connecting the segments 300, 301 and / or the connection arrangements 307 for rotary motion together.

[0110] The illustrated connection arrangements 307 comprise a length of shaft with an articulated connection at both ends.

[0111] Each segment 300, 301 shown includes a helical flight 302 about a central shaft 303. The central shaft 303 is elongate and hollow. The ends of the central shaft 303 may be sealed to prevent fluid entering the central shaft. A hollow central shaft 303 may provide buoyancy to at least partially counteract the mass of the helical flight 302 and any connection / connection arrangement 307. In the illustrated embodiment, each segment 300, 301 is neutrally buoyant. The fluid flow in the fluid pipe 2 may act to centralise and stabilise the articulated screw rotor fluid pipe insert 3 within the fluid pipe 2 during rotation.

[0112] The helical flight 302 of the illustrated embodiments is solid. The helical flight 302 may have any slope, pitch, height and / or outer diameter, optimised to balance the weight of the segment (and / or the articulated screw rotor fluid pipe insert overall) whilst maximising the conversion of the fluid flow in the fluid pipe 2 into rotation of the articulated screw rotor fluid pipe insert 3.

[0113] As shown, a mounting rod 308 is provided, connected to one end of the articulated screw rotor fluid pipe insert 3 to mount the articulated screw rotor fluid pipe insert 3 within the fluid pipe 2. The mounting rod 308 is also be used for insertion and removal as shown in Figure 2.

[0114] The mounting rod 308 shown is an elongate shaft or similar, extending into or through a fluid pipe entry / exit fitting 306. The mounting rod 308 may transmit rotation of the articulated screw rotor fluid pipe insert outside the fluid pipe to an alternator / generator 230 as shown in Figure 1.

[0115] A pressure seal arrangement 309 may be provided to seal about the mounting rod 308. The pressure seal 309 may allow live insertion and removal of the articulated screw rotor fluid pipe insert 3 whilst fluid is flowing in the fluid pipe 2.

[0116] A string 310 of connection arrangements 307 are provided between the mounting rod 308 and the first segment 300 of the articulated screw rotor fluid pipe insert 3 in the illustrated embodiments. This may allow greater clearance or articulation at entry / exit.

[0117] As mentioned above, Figure 2 shows insertion and removal of the articulated screw rotor fluid pipe insert 3. A launch tube 311 is provided to introduce to and / or remove the articulated screw rotor fluid pipe insert 3 from the fluid pipe 2. The launch tube 311 illustrated attaches to the fluid pipe entry / exit fitting 306. The launch tube may remain attached during operation of the articulated screw rotor fluid pipe insert 3.

[0118] In the illustrated embodiment, a flange fitting 312 may be provided on the launch tube 311 corresponding to a flange fitting 313 on the pipe entry / exit fitting 306. The launch tube 311 may be dimensioned to accommodate the outer diameter of the articulated screw rotor fluid pipe insert 3 relatively closely. The launch tube 311 may have an inner diameter to correspond to the inner diameter of the pipe entry / exit fitting 306 as shown in Figures 2 and 4.

[0119] Figure 5 is a schematic illustration of a sensing apparatus 100 which may include or be associated with an articulated screw rotor fluid pipe insert 3 as hereinbefore described. The sensing monitoring apparatus 100 comprises a base module 110 connected to one end of a sensing fibre 15 provided within a pipe 2. The sensing fibre 15 can be of a pre-set length or may be provided to a length corresponding to that of the fluid pipe 2 to be monitored. If the pipe 2 comprises a branched network, the length of the sensing fibre 15 can be selected to correspond the length of fibre required to loop around all branches of the network to be monitored.

[0120] The base module 110 comprises a light emitter 111 (such as a laser) and a light detector 112 to detect backscattered light and output a detector output signal in response to the detected backscattered light. The base module further comprises a local optical coupling assembly 113 configured to couple the emitter 111 and the detector 112 to the sensing fibre 15.

[0121] The detector output signal comprises multiple channels, each channel corresponding to a particular location along the sensing fibre. Each channel may be defined by reference to the round-trip time for backscattered pulses from the particular location. Neighbouring channels may be defined by the minimum resolvable time interval between backscattered pulses from neighbouring sensing fibre locations. By analysing the detector output signal, indications can be obtained of the condition of the pipe and / or events occurring within or in the vicinity of the pipe.

[0122] The detector 112 typically comprises a photosensor configured to output signals in response to detected backscattered light. Optionally, the detector 112 can also comprise a phase module configured to extract phase information from the photosensor output and thereby generate a detector output signal including phase information. In such cases, each detector output signal channel contains phase information related to the phase of the detected backscattered light from the particular fibre location. As illustrated in Figure 6, the apparatus 100 is connected to a flow processing unit 121, and an analyser 122, in this instance cloud based. One or more users 123 can receive processed data from analyser 122, as required or desired. The skilled person will appreciate that the flow processing unit 121 can be integrated into the analyser 122. The skilled person will also appreciate that the flow processing unit 121 and / or the analyser 122 can each be provided in the base unit 110 or in the cloud.

[0123] As is described schematically in Figure 7, in use, the articulated screw rotor fluid pipe insert 3 illustrated in Figures 1 to 4 may be coupled to a generator module 201 by a switching module 202. The generator module 201 is configured to generate electrical power from rotary motion. A typical generator module, as is known in the art, comprises a rotator element (not shown) and a stator element (not shown), wherein relative movement between the rotator element and stator element against electromagnetic resistance generates an output electrical current. The switching module 201 is configured to switch the apparatus between an active mode where the flow rotor 3 is coupled to the generator module 202 and a passive mode where the flow rotor 3 is not coupled to the generator module 202. Accordingly, in the active mode, the flow rotor 3 drives the rotor element of the generator 202 and electrical power is generated. In the passive mode, the flow rotor 3 does not drive the rotor element of the generator module 202 and no electrical power is generated. Any excess electrical current generated during the active mode can be provided to a local power storage device 204, typically a battery.

[0124] In use, the switching module 201 can be operated in response to a controller 205. This allows the operation of the switching module 201 to automated where appropriate. In particular, this allows the apparatus to operate at a desired duty cycle between active and passive modes.

[0125] In passive mode, the flow rate can be monitored using any detector arrangement. If appropriate, detectors such as relay 30, magnetic field detector 31, light transceiver 32 or sonar transceiver 34 can be powered by the storage device 204. Similarly, a vibrator or sounder 28, 32 to deliver acoustic energy to a sensor fibre or a tube through which the sensor fibre extends or into the fluid pipe itself which is then detected by the sensor fibre can be powered using the storage device where required. In one implementation, the apparatus may run primarily in active mode and periodically switch to passive mode. This allows the apparatus to primarily act as a generator and then occasionally act as a flow sensor. This beneficially ensures that the apparatus has sufficient power to carry out flow sensing whenever in passive mode. It also ensures that

[0126] Operating primarily in active mode also allows any surplus generated power to be stored in the storage device. Where there is available power in the storage device 204, the controller 205 may be configured to control the supply of that power to one or more additional devices 210. In the schematic illustration, the additional devices 210 may include secondary sensors such as a pressure sensor. The skilled person will appreciate that multiple additional sensors 210 could be provided as required or desired.

[0127] A possible switching module arrangement is illustrated in Figure 8. Figure 8 shows alternator 230 for generating power which may be coupled to articulated screw rotor fluid pipe insert 3 as explained above. The alternator 230 may include a device to generate pulses during rotation, which could be magnetic (with Hall Effect or similar sensing), or non-contact IR / ultrasonic switch for example.

[0128] Also shown in Figure 8 is a switch 231 which switches alternator output to charge a battery 232 to store electrical charge for later use, or high impedance / resistance voltage sensor 233. The switch 231 shown is a pulse- width modulated switch between a power generation mode and flow velocity sensing mode as discussed above. The pulse width may be fixed or modified remotely.

[0129] In Figure 8, the energy generation switching profile 234 may provide a greater time period for energy generation whereas the voltage sensing profile 235 is the inverse of energy generation switching profile 234.

[0130] The high impedance / resistance voltage sensor 233 will preferably provide a scaled voltage output relative to flow velocity when no power is being generated and the rotor is rotating freely in the flow velocity sensing mode as discussed above.

[0131] As mentioned above, the switching may occur as a result of a remote trigger input 236 to switch 231. When in the flow velocity sensing mode, the high impedance / resistance voltage sensor 233 may transmit data as acoustic energy 238 for remote detection by a DAS analyser via transmitter 237 or by other means 239, such as fibre data cable, fixed land lines, radio or similar.

[0132] Figure 8 also shows a transmitter 240 associated with the alternator 230, to transmit data from which rotational velocity to fluid flow velocity may be derived remotely. Again, this data may be transmitted as acoustic energy 238 for remote detection by a DAS analyser or by other means 239, such as fibre data cable, fixed land lines, radio or similar.

[0133] The transmitters 237, 240 may transmit data in any format, not limited to pulse data (in which pulse rate may be indicative of rotation speed, with a higher pulse rate representing a higher rotation speed for example), or frequency data (in which the frequency of the signal may be indicative of rotation speed, with a higher frequency representing a higher rotation speed for example). If transmitted as frequency data, the data frequencies may be in a range of between 100Hz to 1kHz. In such embodiments, this can be achieved by connecting the output of the high impedance / resistance voltage sensor 233 to a voltage controlled oscillator. This can thereby directly scale the voltage sensor 233 output to an acoustic frequency output.

[0134] The one or more embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

CLAIMS1. An articulated screw rotor fluid pipe insert comprising at least two screw rotor segments connected in an end-to-end configuration by an articulated connection, each screw rotor segment comprising at least one helical flight about a central shaft.

2. An articulated screw rotor fluid pipe insert for a fluid pipe having an internal diameter, Dpipe, the articulated screw rotor fluid pipe insert comprising at least two screw rotor segments connected in an end-to-end configuration by an articulated connection, each screw rotor segment comprising at least one helical flight about a central shaft wherein a length of each screw rotor segment no greater than Dpipe.

3. An articulated screw rotor fluid pipe insert as claimed in claim 2 mounted for rotation within the fluid pipe about an axis parallel to a direction of fluid flow in the fluid pipe.

4. An articulated screw rotor fluid pipe insert as claimed in claim 2 or claim 3 fixed in position within the fluid pipe such that the fluid flow moving past the helical articulated screw rotor fluid pipe insert drives rotation of the articulated screw rotor fluid pipe insert.

5. An articulated screw rotor fluid pipe insert as claimed in any one of the preceding claims wherein each screw rotor segment has a single helical flight6. An articulated screw rotor fluid pipe insert as claimed in any one of the preceding claims wherein the at least one helical flight of respective screw rotor segments are aligned to maximise rotation under the fluid flow.

7. An articulated screw rotor fluid pipe insert as claimed in any one of the preceding claims wherein the articulated screw rotor fluid pipe insert is or comprises an articulated Archimedes screw rotor with at least two Archimedes screw rotor segments articulated relative to one another.

8. An articulated screw rotor fluid pipe insert as claimed in any one of the preceding claims further comprising an articulated connection arrangement witha length of shaft and an articulated connection at both ends provided between adjacent segments to connect them together.

9. An articulated screw rotor fluid pipe insert as claimed in any one of the preceding claims wherein the central shaft of at least one of the segments is hollow and sealed to prevent fluid entering the central shaft.

10. An articulated screw rotor fluid pipe insert as claimed in any one of the preceding claims wherein each segment is neutrally buoyant.

11. An articulated screw rotor fluid pipe insert as claimed in any one of the preceding claims comprising an end segment provided at a free end of the articulated screw rotor fluid pipe insert and one or more intermediate segments connected by an articulated connection between the end segment and a mount for the articulated screw rotor fluid pipe insert.

12. An articulated screw rotor fluid pipe insert as claimed in claim 11 wherein the central shaft of the end segment comprises a blind or closed end at an opposite end of the end segment to the adjacent intermediate segment.

13. An articulated screw rotor fluid pipe insert as claimed in claim 11 or claim 12 wherein each intermediate segment is provided with an articulated connection at both ends.

14. An articulated screw rotor fluid pipe insert as claimed in any one of claims 11 to 13 wherein the mount is connected to one end of the articulated screw rotor fluid pipe insert to mount the articulated screw rotor fluid pipe insert within the fluid pipe.

15. An articulated screw rotor fluid pipe insert as claimed in claim 14 wherein the mount extends into or through a fluid pipe entry / exit fitting.

16. An articulated screw rotor fluid pipe insert as claimed in claim 15 wherein a pressure seal is provided to seal about the mount.

17. An articulated screw rotor fluid pipe insert as claimed in any one of claims 11 to 16 further comprising a string of articulated connection arrangements, each with a length of shaft and an articulated connection at both ends is providedbetween the mount and a first segment of the articulated screw rotor fluid pipe insert.

18. An articulated screw rotor fluid pipe insert as claimed in any one of the preceding claims wherein the articulated connection further comprising a damping link.

19. An articulated screw rotor fluid pipe insert as claimed in any one of the preceding claims further comprising an electrical power generator mounted thereto.

20. An articulated screw rotor fluid pipe insert as claimed in any one of the preceding claims further comprising a launch tube dimensioned to accommodate an outer diameter of the articulated screw rotor fluid pipe insert closely to insert the articulated screw rotor fluid pipe insert into / remove the articulated screw rotor fluid pipe insert from the fluid pipe.

21. A sensing apparatus for monitoring a fluid pipe, the apparatus comprising: a. at least one sensing fibre provided within the pipe; b. a light emitter for introducing light pulses with particular characteristics into the fibre; c. a light detector module configured to detect backscattering of the light pulses from the sensing fibre in multiple different sensing modes and output a detector output signal in response thereto; d. at least one an articulated screw rotor fluid pipe insert as claimed in any one of the preceding claims configured to generate characteristic acoustic events at a rate indicative of fluid flow velocity; and e. a fluid flow processing unit configured to process the detector output signal to extract a component of the detector output signal derived from said characteristic acoustic events from the detector output signal so as to monitor flow velocity.

22. A power generation and flow sensing apparatus for a fluid pipe, the apparatus comprising:a. an articulated screw rotor fluid pipe insert as claimed in any one of the preceding claims configured to rotate in response to fluid flow within the fluid pipe; b. A rotation rate detector configured to detect the rotation rate of the articulated screw rotor fluid pipe insert and output a signal indicative thereof; c. A generator module driven by the articulated screw rotor fluid pipe insert and comprising a rotator element and a stator element, wherein relative movement between the rotator element and stator element against electromagnetic resistance generates an output electrical current; and d. A switching module configured to switch the apparatus between an active mode where the flow rotor is coupled to the generator module and a passive mode where the flow rotor is not coupled to the generator module.

23. A power generation and flow sensing apparatus as claimed in claim 22 wherein an overall length of the articulated screw rotor fluid pipe insert is varied according to power generation requirements.

24. A fluid pipe system comprising an articulated screw rotor fluid pipe insert as claimed in any one of claims 1 to 20, a sensing apparatus as claimed in claim 21 or a power generation and flow sensing apparatus as claimed in claim 22 or claim 23.

25. A fluid pipe system as claimed in claim 24 wherein the articulated screw rotor fluid pipe insert is insertable into and removable from the fluid pipe via an entry / exit point on the fluid pipe extending transversely to a longitudinal fluid pipe axis.

Images