GB2584844A

GB2584844A - Sampling probe and vaporiser

Info

Publication number: GB2584844A
Application number: GB1908617.2A
Authority: GB
Inventors: Knight Jeremy
Original assignee: JDSE Ltd
Current assignee: JDSE Ltd
Priority date: 2019-06-17
Filing date: 2019-06-17
Publication date: 2020-12-23
Anticipated expiration: 2039-06-17
Also published as: GB2584844B; GB201908617D0

Abstract

A sampling probe 18 and vaporiser 16 for sampling liquid natural gas from a container such as a pipeline 12. Probe has a sampling bore 36 in fluid communication with a fluid inlet 40. The inlet is a critical orifice to enable vaporisation of fluid by a vaporiser assembly 50. The inlet passes into a vaporisation chamber which has a fluid outlet, forming a vaporised fluid flow path. The vaporiser assembly may be a heat exchanger 52 and heating means in communication with exchanger. The element may be formed as an elongate cartridge. The vaporiser assembly may be an insert to the body, which may be attached by a flanged insert. The assembly and body may be insulated and may be insulated by an insertable sleeve of insulation 48. The assembly may further have a drivable valve 17 to open and close the critical orifice/inlet, the valve being in thermal communication with the heat exchanger. There may also be a driving means to actuate the valve. The sample probe may have baffle 20 to direct fluid flow towards the inlet. The fluid inlet may be an orifice plate. The body may include a pipeline-mountable flange 38 for connecting to an access port of a pipeline.

Description

Sampling Probe and Vaporiser The present invention relates to a sampling probe and vaporiser, preferably but not necessarily exclusively for a vaporising a sample of liquefied natural gas from a pipeline. The invention further relates to a liquefied natural gas sample vaporisation system. A 5 method of providing a liquefied natural gas sample vaporisation system is also provided.

Natural gas, whilst predominantly comprised of methane, is a mixture of different gaseous hydrocarbons, typically with a range of boiling points, as well as small percentages of other compounds. For ease of transport and storage, the natural gas is typically liquefied by being cooled to approximately -168°C. It can then be transported in its liquid state in ships, road tankers, and/or pipes to be used, for instance, as a fuel source for power stations.

It is desirable to monitor the composition of liquefied natural gas, particularly at transfer points, to measure its energy content, calorific value, and other relevant properties. It may also be further desirable to monitor the composition to see that it does not contain unacceptable compounds, such as sulphides or mercury. This monitoring can be achieved by withdrawing a sample of the liquefied natural gas from the pipe, vaporising the sample, and then analysing it.

In order to retrieve an accurate measurement of the liquefied natural gas, instant vaporisation must occur. If slow heating of the sample occurs, the more volatile components of the liquefied natural gas will begin to vaporise, causing fractionation can occur. Consequently, the analysed components are not necessarily representative of the liquefied natural gas from the pipe, as the fractionation results in altered concentrations at the point of analysis.

One of the contributing factors associated with premature slow heating of the sample 25 liquid is via the valve which isolates the sampling and analysis system from the process. If the valve is hotter than the liquefied natural gas then heat will be transmitted into the sample, and fractionation can occur.

The present invention seeks to provide a sampling probe and vaporiser, having an integral sampling probe body, which can be installed directly onto the container with minimal exertion on the user's part.

According to a first aspect of the invention, there is provided a sampling probe and 5 vaporiser for vaporising a sample of liquefied natural gas from a container, the sampling probe and vaporiser comprising: a container connector having a vaporiser body having a vaporisation chamber, fluid inlet in communication with the vaporisation chamber, a fluid outlet, and a vaporised-fluid flow path extending from the vaporiser chamber to the fluid outlet, the fluid inlet being a critical orifice dimensioned to enable vaporisation of fluid 10 passing into the vaporisation chamber; a vaporiser assembly to enable vaporisation of fluid passing through the fluid inlet critical orifice and into the vaporisation chamber; and a sampling probe body extending from the container connector, the sampling probe body having a sampling bore which is in fluid communication with the fluid inlet.

A combined sampling probe and vaporiser assembly has not been realised to date, given the difficulties of thermalisation of the fluid inlet of the sampling probe body by the vaporiser. The thermal isolation of the vaporiser assembly within the body of the vaporiser mitigates this problem, allowing for the construction of a single unit which can be easily bolted or otherwise connected onto a main liquefied natural gas pipeline or sample tank.

Optionally, the vaporiser assembly may comprise a heat exchanger and heating means which is in thermal communication with the heat exchanger.

The heat exchanger provides the bulk of the vaporiser assembly, and is positioned inside the container connector. This allows vaporisation to be conducted immediately on entry into the vapori ser, reducing the risk of slow vaporisation leading to fractionation.

Preferably, the heat exchanger may include at least one heater receiver, the heating means comprising at least one heating element receivably engagable within the or each heater receiver. The or each heating element may be formed as an elongate heater cartridge.

Insertable heaters, such as heater cartridges, allow for the heat exchanger to be heated with minimal cold spots generated, which might otherwise affect the vaporisation process.

It also allows for the generation of a sealed unit which can be provided as the single pipe-mountable device.

Optionally, the vaporiser assembly may be formed as an insert which is receivable into the internal volume of the vaporiser body. The vaporiser assembly may be a flanged insert 5 directly connectable to the vaporiser body.

A pluggable insert for a heat exchanger may simplify the assembly of the vaporiser, allowing for complex vaporisation channel geometry to be machined into the heat exchanger.

The sampling probe and vaporiser may further comprise an insulating member inside the 10 vaporiser body to at least in part thermally isolate the vaporiser assembly from the vaporiser body.

An insulating member positioned inside the vaporiser body will provide a barrier to thermalisation with the walls of the container connector, which could otherwise transmit heat to the fluid inlet.

Optionally, the insulating member may be formed as an insertable sleeve of thermally insulating material.

A sleeve may have an advantageous shape, in that it allows for the flanged insert arrangement of the vaporiser to be readily inserted therein and to be cocooned by the sleeve.

The vaporisation assembly may further comprise a drivable valve element receivable in or through an access port, the drivable valve element having a valve member which is drivable to open and close the critical orifice, the valve member being in thermal communication with the heat exchanger to enable vaporisation of fluid passing through the fluid inlet and into the vaporisation chamber.

A valve in the vaporiser allows for selective control over the fluid flow therein, which may be far more preferable than continuous sampling of the liquefied natural gas flow. The valve member advantageously can then act as a flash vaporisation surface very close to the fluid inlet.

Preferably, the drivable valve element may be formed as an elongate valve spindle which extends through the access port.

An elongate spindle allows for the contacting end of the drivable element with the fluid inlet to be spaced apart from the vaporiser assembly, further reducing the risk of thermal 5 conduction to heat the fluid inlet.

Optionally, the access port may be formed as a central bore through the vaporiser assembly for receiving the valve spindle therethrough.

The provision of the access port through a bore, preferably of the heat exchanger, ensures that a valve moving member can be installed without necessarily breaching the thermal 10 insulation which separates the container connector and the vaporiser assembly. This mitigates the risk of alternative thermal pathways being formed to the fluid inlet.

Preferably, the valve spindle may comprise a concave or convex vaporisation surface.

A concave or convex surface improves the effectiveness of the flash vaporisation on the valve member.

In a preferred arrangement, the sampling probe and vaporiser may further comprise a drive means engaged with the drivable valve element to actuate the drivable valve element between the open and closed conditions. Optionally, the drivable element may be a linearly drivable element.

The vaporisation assembly may comprise a heater coupled to the valve member or the 20 drivable valve element.

It may be advantageous to associate the heater with the valve member directly, rather than relying on heating through the air gap between the heat exchanger and the valve spindle. This will reduce any lag in the heating of the tip of the valve member.

Linear drive transmission allows for the minimum amount of contact between the valve 25 spindle and the fluid inlet, whereas for a rotational drive, there would be more transmission components close to the inlet which might increase the risk of heat transfer.

The sampling probe body may include a baffle thereon for directing fluid flow towards an inlet-proximal portion of the sampling probe body.

The flow-directing baffle has the advantageous effect of directing very cold liquefied natural gas along and around the sampling probe body. This has a cooling effect on fluid 5 already drawn into the sampling bore, and may further reduce the heating effects which may still be in effect due to the proximity of the vaporiser.

The fluid inlet may preferably be formed by an orifice plate.

The provision of a dedicated orifice plate for the fluid inlet allows for simpler machining of the interface between the probe body, and the fluid inlet itself Optionally, the vaporiser body may include a pipeline-mountable flange for directly connecting to a flanged access port of a pipeline.

It is preferred that the entire unit be directly mountable to a pipeline, enabling the user to simply bolt on a full sampling array without further adaptation required According to a second aspect of the invention, there is provided a liquefied-natural-gas sample vaporisation system comprising: a container for containing liquefied natural gas; and a sampling probe and vaporiser preferably in accordance with the first aspect of the invention, the sampling probe and vaporiser being engagable with the container such that the sampling probe body at least in part extends into the container for sampling liquefied natural gas therein.

Optionally, the container is a pipeline for transporting flowing liquefied natural gas, the pipeline having a flanged access port, wherein the flanged access port is below a horizontal plane of the main pipe section.

An angular offset may improve gravitational flow of the liquid natural gas into the neck of the flange to cool the sampling probe body, whilst maintaining a viable angle for a user to install the vaporiser. Furthermore, there may then be the additional benefit that any vapour bubbles formed in the neck of the flange do not flow past the sampling tip, which might otherwise result in heating of the sampled fluid therein.

According to a third aspect of the invention, there is provided a method of providing a liquefied-natural-gas sample vaporisation system, the method comprising the steps of a] providing a sampling probe and vaporiser preferably in accordance with the first aspect of the invention; and N directly mounting the sampling probe and vaporiser to a flanged access port of a pipeline to be sampled.

According to a fourth aspect of the invention, there is provided a vaporiser or regulator for a sampling port of a liquefied hydrocarbon sampling container, the vaporiser or regulator comprising: a container connector having a vaporiser body having a vaporisation chamber, fluid inlet in communication with the vaporisation chamber, a fluid outlet, and a vaporised-fluid flow path extending from the vaporiser chamber to the fluid outlet, the fluid inlet being a critical orifice dimensioned to enable vaporisation of fluid passing into the vaporisation chamber; and a heating assembly to enable vaporisation of fluid passing through the critical orifice and into the vaporisation chamber.

According to a fifth aspect of the invention, there is provided a vaporiser for sampling liquefied natural gas that connects directly onto a process line or containment container for liquefied natural gas without requiring an external sample line or separate isolation valve.

The invention will now be more particularly described, by way of example only, with 20 reference to the accompanying drawings, in which: Figure 1 shows an end view into a liquefied natural gas sample vaporisation system in accordance with the second aspect of the invention, with the interior of the main pipe section being visible; Figure 2 is a side representation of the liquefied natural gas sample vaporisation 25 system of Figure 1, showing a cross-section along line C-C through the main pipe section only; Figure 3 shows a full cross-sectional representation of the liquefied natural gas sample vaporisation system of Figure 1 along line C-C, indicating the sampling probe and vaporiser formed in accordance with the first aspect of the invention; Figure 4 shows an enlarged cross-sectional representation of the sampling probe and vaporiser shown in Figure 3 in box B-B; Figure 5 shows an enlarged perspective cross-section through a second embodiment of a sampling probe and vaporiser in accordance with the first aspect of the 5 invention; and Figure 6 a perspective representation of the sampling probe and vaporiser of Figure 5.

Referring to Figure 1, there is shown a liquefied natural gas sample vaporisation system, referenced globally at 10, which is suitable for sampling liquefied natural gas flowing through, for example, a main pipe section 12, though it will be appreciated that the system 10 can be utilised with other containers such as storage tanks in which there is no flow. The main pipe section 12 has a flanged access port 14 which extends therefrom, here being offset from a longitudinal vertical plane of the main pipe section 12, for instance, by 15°, and is in a most preferred embodiment, positioned below the horizontal plane of the main pipe section 12.

A, preferably pipeline-mountable, sampling probe and vaporiser 16 is provided which is connectable to the flanged access port 14, which has a sampling probe body 18 which extends into a main flow path of the main vaporiser body 12, to collect samples of the liquefied natural gas, preferably into a central third thereof for optimum sampling conditions. A baffle 20 is also illustrated, which directs liquefied natural gas flow into the neck 22 of the flanged access port 14.

The sampling probe and vaporiser 16, preferably having an integrated valve 17, as illustrated in Figures 3 and 4, includes a container connector 24, preferably a pipeline connector as illustrated, formed as a vaporiser body 26 having a pipeline-mountable flange 28a at a first end thereof and a second flange 28b at the opposite end, and a flanged insert 30 which is receivable within the vaporiser body 26.

The sampling probe body 18 can be seen in more detail in Figure 2. The sampling probe body 18 is formed as an elongate rod which is mounted at or adjacent to the pipeline-mountable flange 28a of the container connector 24, and has a length which is greater than that of the vaporiser body 26 such that a sampling tip 32 of the sampling probe body 18 is therefore positioned in the main flow path of the main vaporiser body 12.

The baffle 20 is arranged to point against the fluid flow, which flows right-to-left in Figure 2. The baffle 20 has a scoop-shaped end which directs liquefied natural gas into the neck 22 to provide a cooling effect to the sampling probe body 18. At a flange-proximal end 34 of the sampling probe body 18, there may be one or more channels therethrough via which liquefied natural gas can pass to improve this cooling effect, preferably at or adjacent to the first flange 28a of the valve housing 24. This provides for more circulation of the liquefied natural gas in the neck 22.

Other baffle geometries may be provided; to provide the improved cooling effect it is merely required that there is some kind of director which directs the liquefied natural gas flow into the neck 22. The baffle 20 could also be removed completely, if heating of the sampling probe body 18 is not expected to be a major concern.

The outer surface of the sampling probe body 18 is preferably smoothed and/or passivated so as to minimise the disruption to the flow of the liquefied natural gas passing thereover. However, in some arrangements, flow diverter elements may be present on the sampling probe body 18, additionally or alternatively 20 to the baffle, to change the flow thereover. For instance, fins or similar elements to minimise forces on the sampling probe body could be considered. Such elements could also provide some of the functionality of the baffle 20.

The full cross-section of the sampling probe and vaporiser 16 can be seen in Figure 3, and a sampling bore 36 of the sampling probe body 18 can also be seen. The sampling bore 36 extends from the sampling tip 32 through the length of the sampling probe body 18, here terminating at a mounting plate 38 of the sampling probe body 18. The mounting plate 38 is directly mounted or mountable to the pipeline-mountable flange 28a of the sampling probe and vaporiser 16, preferably by welding or brazing to prevent leak pathways forming into the container connector 24.

The dimensions of a fluid inlet 40 may be modified by the provision of an orifice plate 42 which is positionable at or on the mounting plate 38 of the sampling probe body 18.

The fluid inlet 40 is preferably formed as a critical orifice, through which flash vaporisation can occur, though non-critical orifices may also work. A critical orifice is an orifice through which critical flow occurs, and is defined as a choke in which the velocity of fluid flow exceeds the velocity of sound in the fluid. This ensures that any disturbance to the fluid stream occurring downstream of the critical orifice cannot be communicated upstream of the critical orifice. Critical flow is preferred, but any appropriate orifice which will result in the fluid being in an appropriate state for vaporisation will be usable within the scope of the present invention.

The fluid inlet 40 may be in contiguous fluid communication with the sampling bore 36, the orifice plate 42 being formed as a top hat structure. A retaining ring 44 may be provided, welded to the pipeline-mountable flange 28a, which holds a seal 46 in place on the orifice plate 42. The seal 46 may therefore act as a valve seat, against which a valve member can operate, as will be described hereafter. It will be appreciated that whilst, from a manufacturing perspective, a multi-component construction may be preferred, the pipeline-mountable flange 28a, sampling probe body 18, orifice plate 42, seal 46 and/or retaining ring 44 may be integrally formed with one another or in any combination thereof It is preferred that, inside the vaporiser body 26, there is provided an insulating member 48, preferably formed as an insertable sleeve of thermally insulating material, which inhibits therm al transfer between the material of the container connector 24 and the inside of the sampling probe and vaporiser 16. A plastics material such as polytetrafluoroethylene, or silicon glass fabric laminate material could be an appropriate insulating material, such as Tufnol (RTM).

A vaporiser assembly 50 is also provided, which includes a heat exchanger 52 and a heating means for heating the heat exchanger 52. The vaporiser assembly 50 and/or heat exchanger 52 is formed as an insert into the container connector 24, such as the flanged insert shown. An insert flange 54 may be directly connectable, for example via welding, to the second flange 28b of the container connector 24 to form a sealed sampling probe and vaporiser 16.

The container connector 24 and heat exchanger 52, preferably inclusive of the insulating 30 member 48, may collectively form a vaporiser unit 56 to control flow through the fluid inlet 40 to a fluid outlet 58 downstream of the fluid inlet 40, and which is directly mountable to the flanged access port 14 of the main pipe section 12.

The insulating member 48 may preferably shield the entire heating assembly 50 from the vaporiser body 24; however, it will be appreciated that conduction pathways may be permissible if the rate of conduction does not result in heating upstream of the critical orifice. As shown in the Figures, conduction pathways may be permissible, for example, at or adjacent the insert flange 54, if the rate of heating of the orifice plate 42 is negligible based on the cooling at the proximal end 34 of the sampling probe body 18.

The heat exchanger 52 preferably comprises an access port 60 for receiving a drivable element, such as the valve spindle 62 illustrated, a tip of which acts as the actuating valve member 63 as part of the vaporiser assembly 50, and as is best illustrated in Figure 4. The access port 60 may preferably be formed as an elongate central bore through the heat exchange 52, having a seal 64 therein for sealingly engaging with the drivable element. An 0-ring seal 64 is suitable for a valve spindle 62 drivable element.

Whilst the access port is here described as being through the vaporiser assembly 50, and in particular through the heat exchanger 52, it will be appreciated that an access port for a drivable element could be provided as part of the container connector 24 instead.

The heat exchanger 52 also defines a fluid flow path inside the vaporiser unit 56, which allows for vaporised liquefied natural gas to be transported to an analysing station. The fluid flow path in the depicted embodiment comprises a flash vaporisation chamber 66 preferably formed by a void between the internal end of the heat exchanger 52 and the internal surface of the insulating member 48, since the heat exchange 52 is not dimensioned to fill the entire inner volume of the vaporiser unit 56. A path from the flash vaporisation chamber 66 to a vaporiser outlet 58 is formed as a vaporisation channel 68 on the outside of the heat exchanger 52. For manufacturing simplicity, the vaporisation channel 68 is formed on the outer surface of the heat exchanger 52, but it will be appreciated that an internal channel in the heat exchanger 52 would fulfil the same purpose, and may be feasible if the heat exchanger 52 were manufactured using an additive process.

Furthermore, the body of the vaporiser assembly 50 and/or the heat exchanger 52 need not necessarily be cylindrical, but could be polygonal, or similarly geometric. The flow path channel or channels could also be formed by an attachment to a main heat exchanger body, such as by providing fins or ribs on the surface, integrally or not integrally formed.

A heater is provided which is associated with the heat exchanger 52 to form the vaporiser assembly 50. In the depicted embodiment, the heat exchanger has a plurality of elongate receivers 70 which extend into the heat exchanger 52 body, preferably in parallel with the access port 60. Elongate cartridge heaters can then be inserted into the receivers 70 to provide a consistent heating effect therethrough. It will, of course, be appreciated that other heaters could be provided, for instance on the insert flange 54. Since the heat exchanger 52 is formed from a thermally conductive material, the thermal conductance may be sufficient so that cold spots in the vaporiser do no occur.

The valve member 63 of the valve spindle 62 may form a valve for the sampling probe and vaporiser 16. The valve member 63 here has a concave surface 72, best visualised from the enlarged representation of Figure 4, which engages with the seal 46 forming the valve seat at the fluid inlet 40. The valve spindle 62 is associated with a drive means, such as a motor, but which could be a manual actuator, to actuate the valve spindle 62 to drive the valve member 63 between closed and open conditions, preferably in a linear motion.

Whilst the concave surface 72 is illustrated, it will be appreciated that the sealing surface of the valve member 63 could have any geometry which would appropriately close the fluid inlet 40. This could be concave, as in the present embodiment, convex, as discussed in respect of the second embodiment below, flat, pencil or chisel-tipped, or other shapes which will be apparent to the skilled person.

The operation of the valve is therefore as follows. When the valve spindle 62 is in an open condition, as is shown in Figures 3 and 4, liquefied natural gas can flow from the sampling probe body 18, through the sampling bore 36, and into the fluid inlet 40. Liquefied natural gas then passes into the flash vaporisation chamber 66 and directly contacts the hot valve member 63. Flash vaporisation occurs instantaneously, and the risk of fractionation is greatly reduced. The hot valve member 63 therefore acts as the vaporiser, with heat being transferred via the valve spindle 62 via the heat exchanger 52. The vaporised liquefied natural gas can then flow through the vaporisation channel 68 in contact with the heat exchanger 52, so that the sample does not cool and fractionate as it passes towards any analytic equipment downstream of the fluid flow path.

To close the valve, the valve spindle 62 is actuated towards the seal 46 forming the valve 5 seat, closing off the fluid inlet 40. No liquefied natural gas then flows through the fluid inlet 40 and onto the fluid flow path. The valve can then be opened again by linearly actuating the valve spindle 62 away from the fluid inlet 40. The contact between the valve member 63 and the orifice plate 42 or seal 46 is minimal, and is only sufficient to close the fluid inlet 40. As such, thermal conduction from the valve member 63 to the fluid inlet 10 40 is very small, and therefore the risk of boiling of the liquefied natural gas sample in the sampling probe body 18. The presence of the insulating member 48 also serves to isolate the heat exchanger 52 from the orifice plate 42, and therefore additional conduction pathways extending along the container connector 24 to the critical orifice do not form.

The advantages of this arrangement are related to the temperature isolation of the various components. For effective vaporisation, it is not desirable to allow the vaporiser to cool. However, it is very undesirable for thermal transfer through the sampling probe body 18, which could potentially result in alteration of the composition of the sampled liquefied natural gas as some constituents boil too early.

The hot valve member 63 provides a surface against which the liquefied natural gas sample can quickly flash vaporise on entry into the flash vaporisation chamber 66. The hot valve member 63 also has minimal contact with the fluid inlet 40, and therefore thermal conduction pathways are very limited.

The insulating member 48 provides a thermal barrier between the container connector 24 and the heat exchanger 52. This limits the heating of the sampling probe body 18 through the direct connection of the pipeline-mountable flange 28a of the container connector 24 to the flanged access port 14 of the main pipe section 12. The void which forms the chamber 66 inside the vaporiser unit 56 also provides a thermal break between the heat exchanger 52 and the orifice plate 42 and/or retaining ring 44, so that the fluid inlet 40 does not become heated.

The only point of contact via which thermal conduction can occur is where the valve member 63 contacts the seal 46 and/or orifice plate 42. The seal 46 and/or orifice plate 42 itself can be formed from a material having a low thermal conductivity, to mitigate the thermal transfer to the liquefied natural gas sample in the sampling bore 36.Notwithstanding, the baffle 20 on the sampling probe body 18 further acts to counteract any heating effect produced by the valve spindle 62 being in contact with the orifice plate 42, since cold liquefied natural gas is diverted up the neck 22. This cools the mounting plate 38, which in turn provides a cooling effect to the orifice plate 42 and fluid inlet 40.

The orientation of the sampling probe and vaporiser 16 is also important. If, instead of the standard vertical configuration of sampling apparatus as is used in the art, the sampling probe and vaporiser 16 is instead mounted to the main pipe section 12 below a horizontal plane thereof, then there will be many advantages.

Firstly, warmer liquefied natural gas bubbles will not collect in the neck 22 of the flanged 15 access port 14. The warmer bubbles will rise and escape, thereby not imparting a heating effect to the sampling probe 18.

Secondly, the injection of the liquefied natural gas sample into the flash vaporisation chamber 66 against the direction of gravity will create a naturally turbulent flow inside the flash vaporisation chamber 66 and therefore on the fluid flow path. This will encourage mixing of the vaporised sample, and will actively prevent post-vaporisation fractionation prior to analysis.

An alternative sampling probe and vaporiser configuration is shown in Figure 5, the liquefied natural gas sample vaporisation system being indicated globally at 110. Identical or similar components to those described in respect of the first embodiment of the sampling probe and vaporiser will be referenced using identical or similar reference numerals, and further detailed description will be omitted for brevity.

The sampling probe and vaporiser 116 has a container connector 124, preferably having an insulating member 148 within which is housed the heat exchanger 152. A flash vaporisation chamber 166 is then formed between the heat exchanger 152 and the insulating member 148 at or adjacent to the orifice plate 142.

The sampled liquefied natural gas is drawn through the sampling probe body 118 towards the fluid inlet 140, whilst the baffle 120 directs cooling gas across the base of the sampling probe body 118 to maintain the low temperature at or adjacent to the heated valve member 163. It is noted that the channels 174 through the baffle 120 as previously described are illustrated in respect of the present embodiment.

The valve member 163 of valve 117 here has a convex surface, and therefore the very tip thereof contacts the fluid inlet 140 with a very small contact area. When the valve member 163 is retracted via the valve spindle 162, the fluid inlet 140 is opened, and liquefied natural gas can enter the flash vaporisation chamber 166. Flash vaporisation then can immediately occur on the surface of the valve member 163.

The whole liquefied natural gas sample vaporisation system 110 is illustrated in Figure 6. The manual drive handle 176 which is connected to the valve spindle 162 can be seen, which allows for a user to manually open or close the valve, though this could also be pneumatically, electrically, or hydraulically operated. The external valve outlet 158 can also be seen, which has a connector, preferably a screw-threaded connector, for engaging with a pipe manifold to an analysis system. One or more electrical couplings 178 may also be provided, which allow for, for instance, connection of a power source to the heating means and/or to one or more temperature sensors which are internal to the valve housing 124.

Whilst the present invention is described in respect of the sampling of liquefied natural gas, it will be appreciated that any gas for sampling where it is undesirable to heat the sample prior to vaporisation could find utility within the present invention.

Whilst the sampling probe and vaporiser is described as being a fully mountable sampling probe and vaporiser, it will be appreciated that it may be possible for the sampling probe body to be demountably engagable. In this scenario, a vaporiser, exclusive of the sampling probe body, could in theory be provided.

Furthermore, though the valve arrangement is herebefore described as being mounted to a flanged access port of a pipeline for the measurement of flowing liquefied natural gas, it will be appreciated that the techniques described would be equally applicable in the context of sampling liquefied natural gas from a static storage container, such as a tank or reservoir. No baffle would be required in this scenario, since there is no fluid flow to redirect to towards the probe body.

Additionally it may be possible, in future container configurations, that a critical orifice could be engaged directly onto the outer body of the pipeline. In this scenario, the valve could then be directly mounted to the pipeline, and could even be integrally formed 10 therewith as part of an all-in-one sampling system.

Whilst a heat exchanger having a plurality of heating cartridges is herebefore described, it may additionally or alternatively be possible to provide a valve spindle or drivable element which is directly heated, for example, by insertion of a cartridge heater into the drivable element directly. This would allow for direct conduction of heat to the valve mcmbcr, rather than relying upon heat transfer through the air gap between the heat exchanger and the valve spindle. Said heater could alternatively be positioned directly in the valve member, with electrical wiring passing through the valve spindle.

The arrangement has thus far been described in the context of a vaporiser. However, other heated fluid control equipment could also benefit from the present invention.

For example, it may be desirable for there to be provided a thermally-controlled regulator assembly, particularly in the transport or storage of liquefied petroleum gas. Liquefied petroleum gas does not need to be maintained at such a low temperature as liquefied natural gas in order to remain in the liquid phase. As such, there is less of a burden on the user to maintain a thermal barrier between the sampling probe and any valve member of the regulator. It is still, however, desirable for the valve member to be maintained at a high temperature for the regulator arrangement in order for the liquefied petroleum gas to be raised to temperature rapidly, which again, would potentially result in fractionation of the sample to be analysed inside the regulator body.

The regulator may, instead of a fixed-dimension orifice, have a valve inlet which is dimensionally-adjustable, for instance, based on a pressure differential between regulator chambers. Within the regulator, there may be a diaphragm which is engagable with a valve pin, the orifice changing in dimeter as the pressure changes.

As such, it may be feasible to provide a thermally-controllable valve for a sampling port of a, preferably liquefied hydrocarbon, sampling container, in which the valve member is maintained at a high temperature with respect to the valve housing. When the sample is introduced into the valve, its temperature will be rapidly raised, avoiding many of the issues associated with sample fractionation.

The apparatus therefore realises a sampling probe and vaporiser which is provided as a preferably unitary device which can be mounted directly onto a flanged access port of a main pipe section. This negates the need to provide a separate vaporiser downstream of, in particular, a fluid control valve of the system significantly reduces the assembly complexity of the liquefied natural gas sample vaporisation system.

The words 'comprises/comprising' and the words 'having/including' when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of examples only, and various 25 other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.

Claims

Claims 1. A sampling probe and vaporiser for a vaporising a sample of liquefied natural gas from a container, the sampling probe and vaporiser comprising: a container connector having a vaporiser body having a vaporisation chamber, fluid inlet in communication with the vaporisation chamber, a fluid outlet, and a vaporised-fluid flow path extending from the vaporiser chamber to the fluid outlet, the fluid inlet being a critical orifice dimensioned to enable vaporisation of fluid passing into the vaporisation chamber; a vaporiser assembly to enable vaporisation of fluid passing through the fluid inlet critical orifice and into the vaporisation chamber; and a sampling probe body extending from the container connector, the sampling probe body having a sampling bore which is in fluid communication with the fluid inlet.
2. A sampling probe and vaporiser as claimed in claim t, wherein the vaporiser assembly comprises a heat exchanger and heating means which is in thermal communication with the heat exchanger
3. A sampling probe and vaporiser as claimed in claim 2, wherein the heat exchanger 20 includes at least one heater receiver, the heating means comprising at least one heating element receivably engagable within the or each heater receiver.
4. A sampling probe and vaporiser as claimed in claim 3, wherein the or each heating element is formed as an elongate heater cartridge.
5. A sampling probe and vaporiser as claimed in any one of the preceding claims, wherein the vaporiser assembly is formed as an insert which is receivable into the internal volume of the vaporiser body.
6. A sampling probe and vaporiser as claimed in claim 5, wherein the vaporiser assembly is a flanged insert directly connectable to the vaporiser body.
7. A sampling probe and vaporiser as claimed in any one of the preceding claims, further comprising an insulating member inside the vaporiser body to at least in part thermally isolate the vaporiser assembly from the vaporiser body.
8. A sampling probe and vaporiser as claimed in claim 7, wherein the insulating member is formed as an insertable sleeve of thermally insulating material.
9. A sampling probe and vaporiser as claimed in any one of the preceding claims, wherein the vaporiser assembly further comprises a drivable valve element receivable in or through an access port, the drivable valve element having a valve member which is drivable to open and close the critical orifice, the valve member being in thermal communication with the heat exchanger to enable vaporisation of fluid passing through the fluid inlet and into the vaporisation chamber.
10. A sampling probe and vaporiser as claimed in claim 9, wherein the drivable valve element is formed as an elongate valve spindle which extends through the access port.
11. A sampling probe and vaporiser as claimed in claim 10, wherein the access port is formed as a central bore through the vaporiser assembly for receiving the valve spindle 20 therethrough.
12. A sampling probe and vaporiser as claimed in any one of claims 9 to 11, wherein the valve member comprises a concave vaporisation surface.
13. A sampling probe and vaporiser as claimed in any one of claims 9 to 11, wherein the valve member comprises a convex vaporisation surface.
14. A sampling probe and vaporiser as claimed in any one of claims 9 to 13, wherein the vaporisation assembly comprises a heater coupled to the valve member or the drivable 30 valve element.
15. A sampling probe and vaporiser as claimed in any one of claims 9 to 14, further comprising a drive means engaged with the drivable valve element to actuate the drivable valve element between the open and closed conditions.
16. A sampling probe and vaporiser as claimed in any one of claims 9 to 14, wherein the drivable element is a linearly drivable element.
17. A sampling probe and vaporiser as claimed in any one of the preceding claims, wherein the sampling probe body includes a baffle thereon for directing fluid flow towards an inlet-proximal portion of the sampling probe body.
18. A sampling probe and vaporiser as claimed in any one of the preceding claims, wherein the fluid inlet is formed by an orifice plate.
19. A sampling probe and vaporiser as claimed in any one of the preceding claims, wherein the vaporiser body includes a pipeline-mountable flange for directly connecting to a flanged access port of a pipeline.
20. A liquefied natural gas sample vaporisation system comprising: a container for containing liquefied natural gas; and a sampling probe and vaporiser as claimed in any one of the preceding claims, the sampling probe and vaporiser being engagable with the container such that the sampling probe body at least in part extends into the container for sampling liquefied natural gas therein.
21. A liquefied natural gas sample vaporisation system as claimed in claim 20, wherein the container is a pipeline for transporting flowing liquefied natural gas, the 25 pipeline having a flanged access port, wherein the flanged access port is below a horizontal plane of the main pipe section.
22. A method of providing a liquefied natural gas sample vaporisation system, the method comprising the steps of: a] providing a sampling probe and vaporiser as claimed in any one of claims 1 to 19; and N directly mounting the sampling probe and vaporiser o a flanged access port of a pipeline to be sampled.
23. A vaporiser or regulator for a sampling port of a liquefied hydrocarbon sampling container, the vaporiser or regulator comprising: a container connector having a vaporiser body having a vaporisation chamber, fluid inlet in communication with the vaporisation chamber, a fluid outlet, and a vaporised-fluid flow path extending from the vaporiser chamber to the fluid outlet, the fluid inlet being a critical orifice dimensioned to enable vaporisation of fluid passing into the vaporisation chamber; and a heating assembly to enable vaporisation of fluid passing through the critical orifice and into the vaporisation chamber.