Fluid Sampling Device

Abstract

A fluid sampling device for sampling fluids in a fluid process vessel through a port in a wall of the vessel, the sampling device comprising a flexible tube with an open end in fluid communication with the fluid process vessel, means to attach the sampling device to the process vessel, wherein at least a portion of the flexible tube is adapted to extend into the process vessel, wherein the length of the flexible tube extending into the process vessel is at least 5 times the outer diameter of the flexible tube.

Claims

1. A fluid sampling device for sampling fluids in a fluid process vessel through a port in a wall of the vessel, the sampling device comprising a flexible tube with an open end in fluid communication with the fluid process vessel, means to attach the sampling device to the process vessel, wherein at least a portion of the flexible tube is adapted to extend into the process vessel, wherein the length of the flexible tube extending into the process vessel is at least 5 times the outer diameter of the flexible tube, wherein the portion of the flexible tube extending into the process vessel is substantially linear.

2. A fluid sampling device in accordance with claim 1, wherein the portion of the flexible tube extending into the process vessel is substantially linear when in use.

3. A fluid sampling device in accordance with claim 1, wherein the fluid sampling device comprises means to attach the sampling device to the process vessel.

4. A fluid sampling device in accordance with claim 1, wherein the fluid sampling device comprises a valve to open or seal a port in the process vessel.

5. A fluid sampling device in accordance with claim 1, wherein the flexible tube is indirectly or directly in fluid communication with the valve.

6. A fluid sampling device in accordance with claim 5, wherein the fluid sampling device comprises a spacing element between the valve and the flexible tube.

7. A fluid sampling device in accordance with claim 6, wherein the spacing element is a substantially rigid tube in fluid communication with the valve and in fluid communication with the flexible tube.

8. A fluid sampling device in accordance with claim 1, wherein the flexible tube is polymeric.

9. A fluid sampling device in accordance with claim 8, wherein the polymer has high chemical resistance and high heat resistance.

10. A fluid sampling device in accordance with claim 8, wherein the polymer has low permeability.

11. A fluid sampling device in accordance with claim 8, wherein the polymer has a low coefficient of friction.

12. A fluid sampling device in accordance with claim 8, wherein the polymer is a fluoropolymer.

13. A fluid sampling device in accordance with claim 12, wherein the fluoropolymer is selected from the group comprising perfluoroalkoxy (PFA), polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), ethylene-tetrafluoroethylene (ETFE), polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polychlorotrifluoroethylene, polyethylenetetrafluoroethylene and polyethylenechlorotrifluoroethylene.

14. A fluid sampling device in accordance with claim 1, wherein the length of the flexible tube extending into the process vessel is between 5 and 100 times the outer diameter of the flexible tube.

15. A fluid sampling device in accordance with claim 1, wherein, the length of the flexible tube extending into the process vessel is between 50 mm and 1000 mm.

16. A fluid sampling device in accordance with claim 1, wherein, the internal diameter of the flexible tube is 5 mm and 50 mm.

17. A fluid sampling device in accordance with claim 1, wherein, the wall thickness of the flexible hose is between 1 mm and 5 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Further features of the present invention are more fully described in the following description of a non-limiting embodiment thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawing in which:

[0068] FIG. 1 is a cross sectional view of a fluid sampling device in accordance with an embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

[0069] Throughout the specification, unless the context requires otherwise, the word solution or variations such as solutions, will be understood to encompass slurries, suspensions and other mixtures containing undissolved solids.

[0070] Throughout this specification, unless the context requires otherwise, the word comprise or variations such as comprises or comprising, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0071] Those skilled in the art will appreciate that the invention described herein is amenable to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in the specification, individually or collectively and any and all combinations or any two or more steps or features.

[0072] It is known to use tapping points in many industrial settings. Routine maintenance is required on them. In the Bayer process, areas more prone to rapid scaling are those in the green liquor part of the circuit from digestion through to heat exchange and washers (such as post digestion clarifier underflows, thickener and washer underflows and overflows, security filtration and green liquor storage.) and require frequent drilling and exercising of ball valves to prevent any significant failures. Scale can grow rapidly inside the valve, resulting in blockages or seizures, which can cause undesirable process disruptions.

[0073] In FIG. 1, there is shown a cross-sectional view of an embodiment of a fluid sampling device, depicted as a tapping point assembly 10 attached to a process vessel 12. The tapping point assembly 10 comprises a flexible PFA tip 14, with an open end 15, an adaptor 16 to retain a portion of the tip, an isolating ball valve 18, fittings 20 as required depending on the application and a tube 22 as required connected to equipment.

[0074] The tapping point assembly 10 is attached to the boundary surface 24 of the process vessel 12. In the embodiment of FIG. 1 a body 26 of the tapping point assembly 10 is welded to a port 28 in the boundary surface 24. The body 26 comprises preferably an annular shaped base, the welded joint being between the peripheral surface of this base portion and the edge of the port.

[0075] In use, fluid from the process vessel 12 enters the tapping point assembly 10 through the open end 15 of the flexible tip 14. The flexible tip 14 is not permeable to the fluid.

[0076] Flexible PFA tubes in accordance with the present invention have been installed at locations throughout a Bayer circuit.

[0077] Four tubes were installed on tapping points in a thickener overflow launder tank (medium fluid velocity) and remained substantially scale free for the time frames shown below, comparing favourably to standard tapping points which generally require cleaning after 40-50 days.

TABLE-US-00002 TABLE 2 Tube performance. Tube length (mm) Length:Diameter Ratio Days without blockage 100 7 394 200 15 322 300 23 72* 400 30 395 *Failure not related to PFA tip scaling. The tank under trial went offline for overhaul.

[0078] Three tubes were installed on tapping points in a D tank (high fluid velocity) as shown below in Table 3.

TABLE-US-00003 TABLE 3 Tube performance. Tube Length:Diameter Days without Location length (mm) Ratio blockage Level Gauge 75 5 156.sup.1 Clarity Meter 75 5 296.sup.2 Liquor Analyser 75 5 296.sup.2 .sup.1one maintenance activity required .sup.2three maintenance activities required

[0079] Four tubes were installed on tapping points in a D tank (high velocity) as shown below in Table 4.

TABLE-US-00004 TABLE 4 Tube performance. Tube Length:Diameter Days without Location length (mm) Ratio blockage Level Gauge 100 7 105 Liquor Analyser 100 7 92.sup.1 Level Gauge 100 7 92 Liquor Analyser 100 7 92 .sup.1one maintenance activity required

[0080] A D-tank is to be understood as a tank between a thickener overflow and security filtration. In a typical Bayer circuit, liquor may have a residence time of 0.5 hr to about 2 hr.

[0081] Standard tapping points installed in similar environments had a maximum lifespan of 24-35 days.

[0082] A further tube was installed on a thickener underflow with a 100mm protrusion as shown below in Table 5.

TABLE-US-00005 TABLE 5: Tube performance. Tube length (mm) Length:Diameter Ratio Days without blockage 100 7 56

[0083] Standard tapping point installed in similar environments had a maximum lifespan of about 14 days.

[0084] It is known to use/install probes in industrial circuits for regular analysis of fluid properties. Such probes remain in the liquid and depending on the conditions, can be prone to scaling. One application is the use of clarity meter probes on thickener overflow launders. Sampling probes of scale resistant materials or with scale resistant coatings have been tested by the applicant. The applicant's experience that such and sample probe tips do scale over time.

[0085] It is known to use metallic or other rigid probes, tubes or lances that extend into vessels. Such probes can extend by up to 2 m into a vessel. To reduce scaling, stainless steel tips ( diameter) were tipped with PFA which extended out the end of the probe into the vessel by 50 mm to 200 mm. The results showed that all tips of different lengths behaved similarly with significantly reduced rates of scaling. In addition to reducing scaling rates, any scale was simple to remove by distorting (e.g. squeezing) the tip.