WO1989000284A1

WO1989000284A1 - Sampling device

Info

Publication number: WO1989000284A1
Application number: PCT/AU1988/000217
Authority: WO
Inventors: John Casey
Original assignee: ICI Australia Operations Pty Ltd
Current assignee: Orica Australia Pty Ltd
Priority date: 1987-07-06
Filing date: 1988-06-28
Publication date: 1989-01-12
Anticipated expiration: 1990-01-06
Also published as: FI900059A7; DK104989D0; DK104989A; ZA884806B; AU1989688A; FI900059A0

Abstract

A sampling device and process for sampling process fluid. The sampling device is connected in parallel to a sampling line (1) and a four-port valve (3) is utilised to either allow flow of fluid through a sample collection vessel (7) or allow the sample collection vessel (7) to be off-line and the flow of fluid to continue through the sampling line (1). The sampling device significantly reduces the dead-volume in and emissions from current sampling processes. The sampling device has particular use in sampling of process fluids without interruption of the process.

Description

SAMPLING DEVICE

This invention relates to a sampling device. In order to monitor a manufacturing process it is normal practice to routinely collect specimens from process streams to provide valuable quality control information.

In order that the specimens are useful, it is important that they accurately reflect the composition of the process stream.

Currently-used sampling devices generally comprise a branch line in the process system which terminates at a tap which may be operated so as to deliver a portion of the process line contents to a sample-collecting container. Although this system works well, its operation provides several problems. The fluid in such branch lines is frequently not representative of the process fluid as a whole due to factors such as cooling, reaction and crystallization. Consequently, the branch line must first be purged of its contents prior to sampling. This can lead to difficulties where, for example, the process material is air-sensitive. _ 1 — hazardous or environmentally undesirable. Such problems can be overcome by complex systems of valves, but this solution is undesirable from both financial and reliability points of view.

We have now developed a device which overcomes the above problems and is simple and convenient to use.

Accordingly we provide a fluid sampling device comprising:

a) a sampling line adapted to be connected in parallel with a fluid transfer line carrying the fluid to be sampled;

b) a valve dividing the sampling line into inlet and outlet portions; and

c) collecting'inlet and outlet means adapted to communicate with a sample collection vessel;

and wherein the valve has at least two working positions including at least one position wherein the inlet portion and outlet portion of the sampling line are brought into direct communication via the valve, and at least one position wherein the inlet portion and outlet portion of the sample line are brought into communication with respective collecting inlet means and collecting outlet means. The invention thus provides a fluid sampling device which has at least two working modes. It is an inherent property of our device that when in use it may be operated in a purging mode which permits an unhindered flow of the fluid through the sampling line, or in a sample-collecting mode in which the flow of the sampling line is deviated through a sample collection vessel. It is preferred that the sampling device comprise a sample collection vessel adapted so that in use the vessel cooperates with the collecting inlet and outlet means to provide a substantially airtight seal between collecting inlet and outlet means and interior of the vessel.

In a preferred embodiment, the collecting inlet and outlet means are injection needles and the sample collection vessel comprises a bottle, the opening of which is sealed with a septum. It is particularly preferred that the collection means is provided by a dual needle wherein- one of the needles is located within and essentially parallel to the other. We have found that the use of the dual needle system provides additional safety against leaks from the sample collection vessel. Although our device may be operated efficiently using two separate injection needles, we have found that the use of the dual needle system overcomes several problems with such systems.

The use of a dual needle system allows the area of unsupported septum to be significantly reduced This leads to advantages in reliability. Reducing the area of unsupported septum allows the pressure differential which can be applied across the septum to be increased while retaining the advantages of lea -proof operation. The geometry of a single penetration point of the septum further reduces the risk of failure.

When two separate needles are used, it is preferable that these needles be approximately parallel. The possibility of leakage during the insertion of these needles through the septum into the sample collection vessel is reduced when the needles are approximately parallel. In a dual needle system, the needles may be coaxial; however, the system will operate efficiently when the needle openings are not precisely concentric. Indeed we have found that the possibility of blockage of the needles by septum material is significantly reduced if the inner needle is not concentric with the outer needle.

In order to further reduce the chances of the needles becoming obstructed by particles of septum material, it is preferred that the end of the inner needle extend beyond that of the outer needle, and that preferably the end of the inner needle be so shaped as to form an acute-angled tip. It is further preferred that the tip of the inner needle be curved towards the axis of the inner needle. Curving the tip of the inner needle reduces the likelihood of coring the septum by the penetration of the needle.

Preferably the outer needle is supported at its end by being connected to the inner needle by means of a support which joins the two needles across the annular gap between them. Such a connection strengthens the dual needle and allows a longer dual needle to be used than would otherwise be possible.

We have found it convenient to join the needles in this manner at the end of the outer needle, preferably using silver solder. Alternatively, the annular gap between the outer needle and the inner needle may be filled, completely sealing the end of the outer needle, and a port provided in the wall of the outer needle to allow a flow of fluid when in use.

In a preferred embodiment, the sampling device of the invention further comprises means for retaining a sample collection vessel in communication with the collecting inlet and outlet means. In a preferred embodiment, the retaining means engages the side of the vessel and provides a lateral restraining force to the vessel, while providing alignment for communication of the vessel with the collecting inlet and outlet means; and whereby the vessel may be brought into communication with the collecting inlet and outlet means by movement of the vessel within the retaining means. Where the collecting inlet and outlet means are needles, a particularly preferred retaining means comprises at least three retaining members essentially parallel to the needles and located such that when the vessel is in position to collect samples, the vessel is held by the retaining members providing alignment for communication of the septum with the needles. The retaining members allow the vessel to engage the needles through the septum. A particularly convenient retaining means comprises a U-shaped guide, providing two retaining members, and a co-acting leg, providing a third retaining member. Preferably the co-acting leg is made of resilient material to allow the vessel to be removably inserted between the U-shaped guide and co-acting leg. More preferably the co-acting leg comprises a foot disposed toward the U-shaped guide to provide a stop for the base of the bottle. In a further preferred embodiment, there is provided a cage adapted to house the sample collection vessel, wherein the vessel is rigidly held, said cage being slidably connected to a retaining means providing means for alignment for communication of the vessel with the collecting inlet and outlet means and whereby the vessel may be brought into communication with the collecting inlet and outlet means by sliding movement of the cage along the retaining means. It will be apparent to those skilled in the art other means for locating the sample collection vessel are useful in conjunction with the present invention. In a further aspect of the present invention there is provided a process for sampling fluid in a fluid transfer line wherein a portion of fluid from the fluid transfer line is diverted through a sampling device wherein the fluid passes through an inlet portion of a sampling line, through a valve, and is returned to the fluid transfer line via an outlet portion of the sampling line wherein the value in a first operating mode diverts the fluid through a sample collection vessel to the outlet portion of the sampling line and in a second operating mode allows- the fluid to communicate with the outlet portion of the sampling line whereby the sample collection vessel is off-line. Preferably in the present process flow of fluid through the sampling line is induced by a pressure differential in the fluid transfer line • across the fluid sampling device. This flow may be facilitated by connecting the inlet and outlet portions of the sampling line to regions of high pressure and low pressure respectively in the fluid transfer line.

It is further preferable that the sample collection vessel is adapted to allow information to be recorded by instrumental techniques.

It will be apparent to those skilled in the art that fluid material may be added to a fluid transfer line using a sampling device according to claim 1 wherein the fluid material to be added to the fluid transer line is initially contained in the sample collection vessel and continuously delivered to the fluid transfer line by diverting the flow of the sampling line, via the valve, through the sample collection vessel. Embodiments of the invention will now be described with reference to the attached drawings In the drawings:-

Fig. 1 is a perspective view of a sampling device of an embodiment of the invention.

Fig. 2 is a part section of a sampling device of the invention.

Fig. 3 is a perspective view of a sampling device of another embodiment of the invention.

Fig. 4 is an underneath perspective of a sampling device depicting a retaining means.

Fig. 5 is a perspective view of a sampling device depicting a further retaining means.

Figure 1 shows a sampling device comprising a four port valve (3), connected to which are a sampling line inlet portion (1), a sampling line outlet portion (2), a collecting inlet means (4) and a collecting outlet means (5) . The collecting inlet and outlet means are shown as hypodermic type needles.

In operation the valve may be positioned using the valve handle (6) in a first mode wherein the inlet (1) and outlet (2) portions of the sampling line are in direct communication via the valve (3). This allows the sampling line to be continuously purged, even when the sample collection vessel (7) has been removed from the system. In order to collect a process sample the collecting means (needles (4) and (5) ) are introduced to a collection vessel (7) through a septum (8) which seals the opening of the bottle (7).

In cases where the process material is particularly air-sensitive, the bottle may first be flushed with an inert gas such as nitrogen.

Fig. 2 shows an embodiment of the invention operating in the sample collecting mode. The flow of material has been diverted through the sampling vessel (7) by operation of the valve handle (6) to rotate the valve (3), simultaneously bringing the inlet portion of the sampling line (1) into communication with the collecting inlet means (4) and bringing the outlet portion of the sampling line (2) into communication with the collecting outlet means (5) .

The dotted lines in the valve body show clearly an alternate position of the valve. Thus, when the valve is in the alternate position (the sample collection vessel is off-line) process fluid flows through the sampling line and back into the process line. The sampling vessel (7) may be filled to any level with sampling material, the maximum collection volume being determined by the volume of collection space below the port of the outlet needle (5) and the over pressure of the sample fluid relative to the original sample vessel internal pressure. Once the sample fluid has reached the level of port of collecting outlet means the device will provide continual flow of fluid through the sampling container. This allows a representative sample to be collected over an extended period of time with a minimum of operator supervision. Fig. 3 shows an embodiment of the present invention in which the collection ports are provided by a dual needle. The inner needle (4) provides the inlet collecting means and extends beyond the end of the outlet collection means (5).

At the opening of the outer needle (5) the needles are joined by silver solder (15) which partially fills the circumference of the annulus between them. The smooth tapered join (15) reduces the tendency of the needles to tear the septum and provides higher compression of the septum, making the needle/septum combination leak free.

In Fig. 1, 2 and 4, the retaining means (9) comprises a U-shaped guide (10), having retaining members (11), which are approximately parallel with the needles (4,5), and a co-acting leg (12) which combines with the U-shaped guide to provide a lateral restraining force to the vessel(7).

In Fig. 4, a foot (13) provides a stop for the base of the vessel, preventing the vessel (7) from falling from the end of the retaining means. The foot (13) which forms part of the co-acting leg (12) may also comprise a right angle portion (14) which inhibits excessive lateral movement of the co-acting leg (12).

A vessel (7) may be removably introduced to the guide by forcing movement of the co-acting leg (12).

Figure 5 shows a sample collection vessel (7) housed rigidly within a cage (15) wherein said case (15) is slidably mounted on retaining means (16) via a sliding means (17). There is provided in said case (15) a port (18) for viewing or optically testing the fluid sample. - lo ¬ in order to hold the sample collection vessel (7) in communication with sample collecting inlet and outlet means ((4) and (5) respectively) through the septum (8) there is provided a holding pin (19). The holding pin (19) passes through corresponding apertures (20) and (21) in the sliding means and in the retaining means, maintaining the collecting inlet and outlet means in communication with the sample collection vessel. In use, the sampling line is connected in parallel with a fluid transfer line. The fluid transfer line may be any line through which fluid is caused to flow. The fluid transfer line may be, for example, a process line which is part of a manufacturing process or a flow line in a laboratory scale reaction apparatus.

It is preferred that flow through the sampling line be induced by a pressure differential in the fluid transfer line across the fluid sampling device.

The inlet of the sampling line may be located at a point of relatively high pressure which, for example, would occur before (or in) a constriction in the fluid transfer line such as a valve or orifice and the outlet of the sampling line may then be located after the constriction. We have found it particularly convenient to locate the sampling line across a pump so that the flow of fluid through the sampling line is in the opposite direction to the flow in the fluid transfer line, thus utilizing the pressure differential across the pump.

The skilled artisan will be aware of many alternative ways in which a pressure differential may be provided. Hence, in a further embodiment of the invention, there is provided a sampling device as herein described and wherein the inlet and outlet of the sampling line are connected to regions of high pressure and low pressure respectively in the fluid transfer line.

The present invention enables the dead volume inherent in prior art branch line systems to be virtually eliminated. In operation, the sampling line may be thoroughly purged without collecting or wasting fluid and it is not necessary that the sample collecting vessel be on-line. The device eliminates sampling emissions and does not require constant monitoring of the filling level as the collecting mode diverts flow through the vessel without the danger of overflow. Indeed, it may be particularly advantageous to allow large volumes of sample fluid to be diverted through the vessel to obtain a representative sample over an extended period of time.

To remove the sample for testing, the material flow may be rediverted by operation of the valve and the vessel removed.

A further aspect of the invention provides a process for collecting a sample of fluid comprising providing a flow of fluid in a sampling line connected in parallel with a fluid transfer line and diverting the flow in the sampling line through a sample collection vessel. Although the device of the invention is primarily of use in sampling from a fluid transfer line, it may also be used for other purposes such as the obtaining of visual or instrumental information about the fluid or the addition of materials to the fluid transfer line. The sampling device of the present invention has the advantage of allowing visual examination of the process fluid without the need to disconnect the sampling container or waste sample material. As previously described, in operation the contents of the sampling line, once the vessel is filled, are returned to the fluid transfer line. Hence the device of the invention provides a means for adding material to the fluid transfer line. For example, additives such as dopants or tracers may be delivered to the fluid transfer line by placing the additives in the vessel and diverting the flow of the sampling line through the vessel. Over a period of time the contents of the vessel will be flushed into the fluid transfer line.

It will be understood that the nature of the fluid is not narrowly critical as the device of the invention may be used to collect samples in a variety of processes. The fluid may, for example, be a liquid, gas, suspension or a gas/liquid mixture.

Claims

The claims defining the invention are as follows:

1. A fluid sampling device comprising:

a) a sampling line adapted to be connected in parallel with the fluid to be sampled.

b) a valve dividing the sampling line into inlet and outlet portions; and

c) collecting inlet and outlet means adapted to communicate with a sample collection vessel;

and wherein the valve has at least two working positions including at least one position wherein the inlet portion and outlet portion of the sampling line are brought into direct communication via the valve, and at least one position wherein the inlet portion and outlet portions of the sample line are brought into communication with respective collecting inlet means and collecting outlet means.

2. A fluid sampling device according to claim 1 wherein there is provided a substantially airtight seal between collecting inlet and outlet means and interior of the vessel.

3. A fluid sampling device according to either claim 1 or claim 2 wherein the collecting inlet means and the collecting outlet means are injection needles and wherein the sample collection vessel comprises a septum, sealing an opening in the sample collection vessel.

4. A fluid sampling device according to anyone of claims 1 to 3 inclusive wherein the collecting inlet and outlet means are provided by a dual needle wherein one of the needles is located within, and essentially parallel to, the other.

5. A fluid sampling device according to claim 4 wherein the inner needle of the dual needle is not concentric with the outer needle.

6. A fluid sampling device according to either of claims 4 or 5 wherein the end of the inner needle extends beyond the end of the outer needle.

7. A fluid sampling device according to any one of claims 4 to 6 wherein the end of the inner needle extends beyond the end of the outer needle and wherein the end of the inner needle is so shaped as to form an acute-angled tip.

8. A fluid sampling device according to claim 7 wherein the tip of the inner needle is curved towards the axis of the inner needle.

9. A fluid sampling device according to any one of claims 4 to 8 wherein the outer needle is supported at its end by being connected to the inner needle by means of a support which joins the two needles across the annular gap between them.

10. A fluid sampling device according to any one of claims 4 to 8 wherein the annular gap between the outer needle and the inner needle is filled, completely sealing the end of the outer needle, and a port is provided in the wall of the outer needle to allow a flow of fluid.

11. A fluid sampling device according to claim 3 wherein the injection needles are substantially parallel.

12. A fluid sampling device according to any one of claims 1 to 11 wherein there is provided a sample collection vessel retaining means and wherein said retaining means provides alignment for communication of the vessel with the collecting inlet and outlet means.

13. A fluid sampling device according to claim 12 wherein the retaining means provides a lateral restraining force to the vessel and wherein the vessel may be brought into communication with the collecting inlet and outlet means by movement of the vessel within the retaining means.

14. A fluid sampling device according to any one of claim 3 to 11 wherein there is provided a sample collection vessel retaining means, wherein said retaining means provides alignment for communication of the vessel with the collecting inlet and outlet means and wherein the retaining means comprises at least three retaining members and wherein said retaining members are essentially parallel to the needles.

15. A fluid sampling device according to claim 14 wherein the retaining means comprises a U-shaped guide, providing two retaining members and a co-acting leg, providing a third retaining member.

16. A fluid sampling device according to claim 15 wherein the co-acting leg is made of resilient material whereby allowing the vessel to be removably inserted between the U-shaped guide and co-acting leg.

17. A fluid sampling device according to claim 14 wherein there is provided a cage adapted to house the sample collection vessel wherein the vessel is rigidly held, said cage being slidably connected to a retaining means providing means for alignment for communication of the vessel with the collecting inlet and outlet means and whereby the vessel may be brought into communication with the collecting inlet and outlet means by sliding movement of the cage along the retaining means.

18. A process for sampling fluid in a fluid transfer line wherein a portion of fluid from the fluid transfer line is diverted through a sampling device wherein the fluid passes through an inlet portion of a sampling line, through a valve, and is returned to the fluid transfer line via an outlet portion of the sampling line wherein the value in a first operating mode diverts the fluid through a sample collection vessel to the outlet portion of the sampling line and in a second operating mode allows the fluid to communicate with the outlet portion of the sampling line whereby the sample collection vessel is off-line.

19. A process according to claim 18 wherein flow of fluid through the sampling line is induced by a pressure differential in the fluid transfer line across the fluid sampling device.

20. A process according to claim 19 wherein the inlet and outlet of the sampling line are connected to regions of high pressure and low pressure respectively in the fluid transfer line.

21. A process for sampling fluid in a fluid transfer line according to any one of claims 18 to 20 wherein the sample collection vessel is adapted to allow information to be recorded by instrumental techniques.

22. A process for adding fluid material to a fluid transfer line using a sampling device according to claim 1 wherein the fluid material to be added to the fluid transfer line is initially contained in the sample collection vessel and continuously delivered to the fluid transfer line by diverting the flow of the sampling line, via the valve, through the sample collection vessel.

23. A sampling device substantially as hereinabove defined with reference to any one of figures 1 to 5 inclusive.

24. A process for sampling fluid in a fluid transfer line utilizing a sampling device substantially as hereinabove defined with reference to any one of figures 1 to 5 inclusive.

25. A process for adding fluid material to a fluid transfer line utilizing a sampling device substantially as hereinabove defined with reference to any one of figures 1 to 5 inclusive.