AU2012203239B2 - Improved sampling apparatus and method - Google Patents

Abstract

Abstract According to the present invention there is provided a sampling apparatus for obtaining a sample volume of a liquid from a body of liquid and delivering the sample volume to an external vessel. The means of transferring the liquid to and from the sample cylinder is via a gravity feed, which avoids many of the prior art problems which are characterised by pressure differentials, disturbing the sedimentation of the liquid to be analysed - and complexity of equipment. (Figure 4)

Description

AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION PATENT OF ADDITION TO AU 2009206170 FOR AN INVENTION ENTITLED Improved Sampling Apparatus and Method The invention is described in the following statement:- -2 IMPROVED SAMPLING APPARATUS AND METHOD Related Application The present application is a Patent of Addition to Australian patent 5 application no. AU 2009206170, to Oscillation Pty Ltd. The content of AU 2009206170 is incorporated by reference herein in its entirety. Field of the Invention The present invention relates to an apparatus and method for obtaining a 10 sample volume of a liquid. The apparatus and method are particularly useful for use in the sampling of high temperature and/or potentially harmful or corrosive liquids. The present invention employs a gravity feed system rather than the series of pressure differentials that characterises the prior art. Although the 15 invention will be described hereinafter with reference to its application within the alumina industry, it will be appreciated that it is not limited to this particular field of use. Background of the Invention 20 Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field. Many processes require a sample volume of liquid to be obtained from a larger body of that liquid for analysis. From the analysis of the sample volume 25 calculations can be undertaken to determine/estimate the properties of the liquid in the larger body. For example, a sedimentation test of liquid may be undertaken in which the rate of settlement of particulate matter in the liquid is analysed. In the fields of mining, agriculture and waste water treatment, for example, it is necessary to 30 separate particulate matter from liquid such as water. Removal of the particulate matter is typically achieved via gravitational settlement of the particles, the rate of which is partly dependent on the mass of those particles. In - 3 many cases a flocculant is added to the body of water to induce the particles to aggregate or floc together which serves to increase the mass of the particles and accelerate the rate of sedimentation (and therefore the efficiency of the separation process). 5 As flocculant chemicals are expensive and may have undesirous environmental effects, it is desirable to add only sufficient flocculant to the body of water to achieve the most cost and/or environmentally efficient rate of sedimentation. By taking a sample of the liquid the rate of sedimentation of that sample can be determined (and extrapolated to the rate of sedimentation of the 10 body of liquid) and the amount of flocculant required calculated. In order to obtain an accurate measure of the rate of sedimentation, the sample must be taken carefully, that is, without undue turbulence, to avoid damaging the sample (i.e., by breaking up the aggregated particles), which could lead to skewed calculations. Further, regular samples are taken to enable 15 real-time information relating to the rate of sedimentation, to enable the amount of flocculant to be added to be adjusted as the characteristics of the inflow stream vary. One known problem with sampling liquids in high temperature environments is that a suction force applied to the sample in order to draw the 20 sample from the depth of the sampling tank tends to cause the sample to boil, thereby leading to undesirable turbulence and consequent break-up of the flocculated particles. A complex network of suction and pressure-equalising tubing is both energy and labour-inefficient. It is an object of the present invention to 25 overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. Accordingly, a preferred form of the present invention relates to a relatively simple, gravity-derived method of obtaining a sample - and subsequent gravity-derived means for its return to the bulk fluid from which it was sampled. 30 Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be -4 construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to". Although the invention will be described with reference to specific examples it will be appreciated by those skilled in the art that the invention may 5 be embodied in many other forms. Summary of the Invention According to a first aspect of the present invention there is provided a sampling apparatus for obtaining a sample volume of fluid from a bulk fluid, 10 said apparatus comprising: feed means for transporting said sample volume of fluid from said bulk fluid; a sample chamber for receiving said sample volume; sample means operatively associated with said sample chamber 15 for analysing said sample volume of fluid; drainage means for emptying said sample chamber; and control means to automate and control the interaction of said feed means with said sample chamber; and said sample chamber with said drainage means; 20 wherein said bulk fluid is elevated with respect to said sample chamber and said sample chamber is elevated with respect to said drainage means, said sample volume of fluid thereby transported from said bulk fluid to said drainage means via gravity flow; and wherein the sample chamber operates such that the liquid is not 25 drawn by vacuum, thereby to facilitate operation in high temperature environments without boiling the liquid. In an embodiment, the sample chamber comprises venting means to equalise internal pressure within the chamber. In another embodiment, the feed means comprise a valve selectively operable to allow a predetermined volume 30 of the sample volume of fluid into the sample chamber. Preferably, the predetermined volume is around 3.5 litres.

-5 In an embodiment, the drainage means comprise a valve selectively operable to evacuate, or substantially evacuate the sample chamber. In an embodiment, the sample chamber further comprises cleansing means associated with the control means, thereby to facilitate cleanout of the sample chamber 5 following evacuation of the sample chamber via the drainage means. In an embodiment, the cleansing means comprises a cleaning solution supply operable to flush a cleaning solution though the sample chamber. In an embodiment, the bulk fluid is sourced from a header tank. In an embodiment, the drainage means is fluidly communicable with a 10 bulk treatment tank, or "thickener". Preferably, the apparatus is adapted for use in with high temperature, corrosive liquids such as those characterising the alumina industry. In an embodiment, the high temperature liquid is between about 60 and 105 0 C and/or the liquid has a pH of about 1, or of about 14 - or of anywhere in between. 15 Accordingly and preferably, the internal surfaces of the apparatus that contact with the sample fluid are substantially non-corrodible. In an embodiment, the feed means is a conduit comprising a vent, thereby to substantially equalise the pressure within the conduit. In an embodiment, the sample means are adapted to analyse 20 predetermined characteristics of the sample fluid, for instance, temperature, turbidity, pH, etc. According to a second aspect of the present invention there is provided a method for sampling a volume of fluid from a bulk fluid, said method comprising the steps of: 25 transporting or inflowing said sample volume of fluid from said bulk fluid to a sample chamber for receiving said sample volume; analysing said sample volume of fluid using sample means operatively associated with said sample chamber; emptying said sample chamber via a drain; wherein 30 said sample means is operated via control means to automate and control the inflow and emptying of said sample volume of fluid; - 5a wherein said bulk fluid is elevated with respect to said sample chamber and said sample chamber is elevated with respect to said drainage means, said sample volume of fluid thereby transported from 5 said bulk fluid to said drainage means via gravity flow; and wherein the sample chamber operates such that the liquid is not drawn by vacuum, thereby to facilitate operation in high temperature environments without boiling the liquid.

-6 In an embodiment, the method further comprises step of venting the sample chamber to equalise internal pressure within said chamber. In an embodiment, the step of transporting is associated with a valve selectively operable to allow a predetermined volume of the sample volume of fluid into 5 the sample chamber. Preferably, the predetermined volume is around 3.5 litres. In an embodiment, the drain is associated with a valve selectively operable to evacuate, or substantially evacuate the sample chamber. In an embodiment, the sample chamber further comprises cleansing means associated with the control means, thereby to facilitate cleanout of the sample chamber 10 following evacuation of the sample chamber via said drainage means. In an embodiment, the cleansing means comprises a cleaning solution supply operable to flush a cleaning solution though the sample chamber. Preferably, the bulk fluid is sourced from a header tank. In an embodiment, the drain is fluidly communicable with a bulk 15 treatment tank, or "thickener". In an embodiment, the method is adapted for use in with high temperature, corrosive liquids such as those characterising the alumina industry. In such industries, the high temperature liquid is between about 60 and 105 0 C and/or said liquid has a pH of about 1, or of about 14. Other pH values are also applicable to the present invention. 20 In an embodiment, any internal surfaces that contact with said sample fluid are substantially non-corrodible. In an embodiment, the transportation takes place in a conduit comprising a vent, thereby to substantially equalise the pressure within the conduit. In an embodiment, the sample means are adapted to analyse 25 predetermined characteristics of the sample fluid, for instance, temperature, turbidity, pH, etc. According to a third aspect of the present invention there is provided a sample, when taken from a volume of bulk fluid by a method as defined according to the second aspect of the present invention. 30 The "parent" application, AU 2009206170, provides a sampling apparatus for obtaining a sample volume of a liquid from a body of liquid and delivering the sample volume to an external vessel, the apparatus including: a -7 sample chamber adapted to be located below a liquid surface level of the body of liquid; a sample inlet from which liquid from the body of liquid can enter the sample chamber; a sample outlet providing for fluid communication between the sample chamber and external vessel; a sample chamber pressure adjustment 5 means operable to adjust pressure in the sample chamber; wherein operation of the sample chamber pressure adjustment means is used to apply a positive pressure to the sample chamber to thereby cause the sample volume to be evacuated from the sample chamber to the external vessel via the sample outlet. The sample inlet may include an inlet valve selectively operable to open 10 the sample chamber to allow fluid flow between the body of liquid and sample chamber and to close the sample chamber to prevent fluid flow between the body of liquid and sample chamber. The sample chamber pressure adjustment means may include a sample chamber atmosphere valve by means of which the sample chamber can be 15 opened to atmospheric pressure and a sample chamber pressure valve through which compressed gas can be directed into the sample chamber. The external vessel may include an external vessel pressure adjustment means. The external vessel pressure adjustment means may include an external vessel atmosphere valve by which the external vessel can be opened to 20 atmospheric pressure and an external vessel pressure valve through which compressed air can be directed into the external vessel. The sampling apparatus may further include a sample controller, the sample controller configured to charge the sample chamber with at least the sample volume by opening the sampling apparatus to atmospheric pressure and 25 opening the sample inlet. Opening the sampling apparatus to atmospheric pressure may include opening the sample chamber atmosphere valve and opening the external vessel atmosphere valve. The sample controller may be configured to evacuate the sample volume from the sample chamber to the external vessel via the sample outlet by closing 30 the sample chamber atmosphere valve, closing the sample inlet, opening the external vessel atmosphere valve, and applying compressed gas into the sample chamber via the sample chamber pressure valve.

-8 The sample chamber may include a first sub-chamber and a second sub chamber, the first and second sub-chambers being in fluid communication with each other. The sample chamber pressure adjustment means may be directly connected to the first sub-chamber and the sample outlet may be formed in the 5 second sub-chamber. The sample chamber may be immersed in the body of liquid. The external vessel may include an external vessel outlet through which any liquid in the external vessel may be drained away. The external vessel may include a cleaning solution supply operable to flush a cleaning solution though 10 the external vessel. In another form of the "parent" application, AU 2009206170, there is provided a method for obtaining a sample volume of a liquid from a body of liquid using a sampling apparatus, the sampling apparatus including a sample chamber located below a liquid surface level of the body of liquid and in fluid 15 communication with an external vessel, the method including: charging the sample chamber with at least the sample volume of the liquid by: opening the sampling apparatus to atmospheric pressure; and opening a sample inlet valve through which liquid from the body of liquid can enter the sample chamber; evacuating the sample volume of the liquid from the sample chamber to the 20 external vessel by: closing the sample inlet valve; applying positive pressure to the sample chamber to force the sample volume out of the sample chamber and into the external vessel. The step of opening the sampling apparatus to atmospheric pressure may include opening the sample chamber to atmospheric pressure and opening 25 the external vessel to atmospheric pressure. The step of evacuating the sample volume of the liquid from the sample chamber to the external vessel may include opening the external vessel to atmospheric pressure. The step of applying positive pressure to the sample chamber may include introducing compressed air into the sample chamber. 30 The method may further include: evacuating the sample volume of the liquid from the external vessel; and clearing the sampling apparatus.

-9 The step of evacuating the sample volume of the liquid from the external vessel may include: opening the external vessel to atmosphere; and opening an external vessel outlet through which the sample volume drains from the external vessel. 5 Finally, the step of clearing the sampling apparatus may include: closing the external vessel to atmosphere; opening the sample inlet valve; introducing compressed gas into the external vessel, the compressed gas flushing any residual liquid in the sampling apparatus out through the sample inlet valve. 10 Brief Description of the Figures A preferred embodiment of the invention will now be described with reference to the accompanying Figures, in which: Figure I provides a schematic diagram of a sampling apparatus in accordance with an embodiment of the "parent" invention, AU 2009206170; 15 Figure 2 provides a logical depiction of the control circuitry of the sampling apparatus depicted in Figure 1; Figure 3A provides a flowchart outlining the steps involved in obtaining a sample of a liquid using the apparatus of Figure 1; Figure 3B provides a flowchart detailing the steps involved in charging a 20 sample chamber of the sampling apparatus of Figure 1; Figure 3C provides a flowchart detailing the steps involved in delivering a sample volume from the sample chamber of the sampling apparatus of Figure 1 to an external vessel; Figure 3D provides a flowchart detailing the steps involved resetting the 25 sampling apparatus of Figure 1; Figure 4 shows a generalised layout of a large-scale processing plant, with the header tank elevated (preferably) 3 to 10 metres above the thickener; and Figure 5 shows a flowchart outlining the steps involved in obtaining a 30 sample of a liquid using the apparatus of Figure 4.

- 10 Detailed Description of the Preferred Embodiment The sampling apparatus and method of the present invention will be described in relation to sampling in the alumina industry. In the alumina industry samples are taken from a high-temperature (around 105 'C) caustic 5 liquid and then analysed to determine the rate of sedimentation particulate matter in the liquid. It will be appreciated that despite this specific application of the invention, the sampling apparatus and method described herein may be suitably used in any industry or process requiring a sample volume of a liquid to be 10 captured from a body of that liquid. One such example is that of refractory materials. Before describing the present invention, it is worthwhile describing, generally, the "parent" invention embodied in AU 2009206170. Figure 1 provides a schematic view of a sampling apparatus 100 in accordance with an 15 embodiment of the "parent" invention. The sampling apparatus includes a sample chamber 102 which is immersed in a body of liquid 104. The body of liquid 104 is, in this instance, held in a tank 106, and has a liquid surface level 108. The sampling apparatus 100 further includes a sample inlet 110 which is 20 controlled by a sample inlet valve 112 which is operable to allow or prevent fluid flow from the body of liquid 104 into the sample chamber 102 and vice versa. As can be seen, the sample inlet valve 112 is located relatively close to the surface level 108. By so locating the sample inlet valve 112 access to the valve 112 (and consequently maintenance of the valve 112) is simplified. 25 Further, by being located relatively close to the surface level 108 the valve 112 is subjected to less pressure than would be the case if it were located deeper in the body of liquid 104, reducing the likelihood of pressure leakage and/or damage to the valve 112. The sampling apparatus is also provided with a sample chamber 30 pressure adjustment means, generally indicated by arrow 114, which is selectively operable to adjust the pressure in the sample chamber 102. The pressure adjustment means 114 includes a sample chamber atmosphere valve - Il 116 which is operable to open the sample chamber 102 to atmospheric air pressure and a sample chamber pressure valve 118 through which pressure can be applied to the sample chamber 102. In this embodiment the pressure is applied via compressed air, and as such the sample chamber pressure valve 118 5 is connected to a compressed air supply 120 for supplying the compressed air and an air regulator 122 by which the pressure of the compressed air supplied through the compressed air pressure valve 118 can be regulated. While the pressure adjustment means 114 has been described and depicted as including two separate valves 114 and 116 it would, of course, be 10 possible to combine these into a single three-way valve if so desired. The sampling apparatus also includes a sample chamber outlet 124 providing fluid communication between the sample camber 102 and an external vessel 126 (and vice versa) via a transfer conduit 128. As can be seen, in the illustrated embodiment the sample chamber 102 15 includes first and second vertical sub-chambers 130 and 132 in fluid communication with each other via a horizontal sub-chamber 134. The sample chamber inlet 110 and sample chamber pressure adjustment means 114 are connected at the first sub-chamber 130 and the sample chamber outlet 124 is connected at the second sub-chamber 132. 20 Alternative arrangements of the sample chamber 102 would, of course, be possible. For example, the sample chamber 102 could be provided as a single (or multiple) straight or coiled tube/pipe arrangement, and may be oriented vertically, horizontally or at any angle therebetween. The location of the sample chamber 102 below the liquid surface level 25 108 allows the sample chamber 102 to be charged with a sample volume of the liquid simply by opening the sample chamber 102 to atmospheric pressure and opening the sample inlet valve 112 (i.e., without requiring additional positive or negative pressure to be applied to the sample chamber 102). While the sample chamber 102 has been depicted and described as being immersed within the 30 liquid in the tank 106, it would of course be possible to achieve this by locating the sample chamber 102 outside the tank 106 (though still below the liquid surface level 108). For example, the sample chamber 102 could be located - 12 outside the tank 106 with the sample inlet 110 passing through the wall (or floor) of the tank 106. Once the sample chamber 102 has been charged positive pressure is applied to the sample chamber 102 by the sample chamber pressure valve 118 in 5 order to evacuate the sample volume into the external vessel 126. During the evacuation under positive pressure not all of the liquid captured in the sample chamber 102 will be delivered to the external vessel 126. As such the volume of liquid captured in the sample chamber 102 (and hence the volume of the sample chamber 102 itself) may need to be greater than the desired sample 10 volume (i.e., the final volume to be delivered to the external vessel 126 and analysed). The external vessel 126 (into which the liquid sample captured in the sample chamber 102 is delivered) includes an external vessel inlet 136 providing fluid communication between the external vessel 126 and the sample 15 camber 102 (and vice versa) via the transfer conduit 128. While the external vessel inlet 136 is depicted as being at the top of the external vessel 126 it could, of course, be located at the bottom (or a side) of the external vessel 126. The external vessel 126 also includes an external vessel pressure adjustment means, indicated generally by arrow 138. The external vessel 20 pressure adjustment means 138 is similar to the sample chamber pressure adjustment means 114 and includes an external vessel atmosphere valve 140 which is operable to open the external vessel 126 to atmospheric air pressure and an external vessel pressure valve 142 through which compressed air can be introduced into the external vessel 126. The external vessel pressure valve 142 25 is connected to a compressed air supply (not shown) and, if desired, may be connected to an air regulator (not shown). Depending on the physical arrangement of the sampling apparatus 100 the external vessel pressure valve 142 may be connected to the same compressed air supply 120 and/or air regulator 122 which provide and regulate compressed air to the sample chamber 30 pressure valve 118. The external vessel 126 also includes a drainage valve 144 operable to drain liquid from the external vessel 126, and a cleaning solution supply valve - 13 146 connected to a cleaning solution source (not shown) by which a cleaning solution (such as water or any other fluid) can be introduced into the external vessel 126. The external vessel 126 is also provided with a liquid level detection 5 means 148 for detecting the liquid level in the external vessel 126 and preventing over-filling of the external vessel 126. As will be appreciated, the external vessel 126 is the vessel from which the sample volume of the liquid is to be analysed. As such, the external vessel 126 may include further or alternative specific features appropriate to the 10 analysis to be undertaken. By way of non-limiting example, and continuing with the alumina industry example where the rate of sedimentation of the liquid is to be measured, the external vessel 126 may be provided with a light source opposite a photo-electric cell by which the rate of sedimentation can be measured. Any other appropriate monitoring and/or analysis device(s) or 15 instrumentation may, of course, also or alternatively be used. Analysis of the sample then takes place; the sampling apparatus is typically submerged to a depth of 2 to 3 metres. However, for larger thickeners, it is conceivable that the sampling apparatus may be submergable up to around 20 metres. 20 The below provides a summary of suitable materials and components of the sampling apparatus 100 in such an environment by way of non-limiting example only. It will be appreciated that different materials and components may be used (and may, in fact, be more appropriate) in different environments. Noting that the sample chamber 102 is submerged in the body of liquid 25 104, the sample chamber may be constructed of 316 stainless steel. As discussed above, the volume of the sample chamber will depend on the sample volume intended to be captured. If, for example, the sample volume is 3.5 L the sample chamber 102 may be provided with two vertical sub chambers 130 and 132 of about 1150 mm long, each having a diameter of about 30 50mm. The horizontal sub-chamber 134 may be approximately 200 mm (also with a diameter of about 50 mm).

- 14 The sample inlet valve 112 is also submerged in the body of liquid 104. A particularly suitable valve for this environment is a diaphragm valve which is advantageous in high temperature and caustic environments as they can be manufactured from 316 stainless steel with appropriate high temperature seals. 5 Additionally, the PTFE (Teflon) diaphragm hermetically seals the hazardous fluid from the operating mechanism of the valve. It will be appreciated, however, that any other type of valve (e.g., a ball valve, butterfly valve, solenoid valve, knife gate valve, pinch valve, etc.) may alternatively be used. As noted above, the positioning of the sample inlet valve 112 near to the 10 surface 108 of the liquid is also advantageous as it reduces the chances of pressure damage/leakage to the valve 112. The transfer conduit 128 may be a Teflon hose of approximately 20 mm diameter and from 7 m to 10 m long (though, as noted above, may well vary beyond these bounds depending on the intended use of the apparatus). As will be appreciated, the liquid passing 15 through the transfer conduit 128 may well be a hazardous material at pressure, and as such the transfer conduit 128 may be further reinforced with a stainless steel braid. As will be appreciated, due to the use of positive pressure to evacuate the sample volume of liquid from the sample chamber 102 to the external vessel 20 126, the dimensions of the sample chamber 102 and transfer conduit 128 are of relevance due to the surface area (and consequent surface tension) they provide to the sample volume. The smaller the diameter of the sample chamber 102 and transfer conduit 128 the more efficient will be the evacuation thereof. However, efficiency of evacuation needs to be balanced against the overall design 25 requirements of the apparatus. The componentry of the sample chamber pressure adjustment means 114 and the external vessel pressure adjustment means 138 is quite similar. As these components are not submerged in the tank 106 and do not come into contact with the liquid in the tank, standard valves and components may be 30 used. For example, the atmosphere valves 116 and 140 and the pressure valves 118 and 142 may be pneumatic solenoid valves as are readily commercially available.

- 15 Further, and as noted above, it would be possible to combine the sample chamber pressure valve 118 and sample chamber atmosphere valve 116 into a single three way valve, and (similarly) the external vessel pressure valve 142 and external vessel atmosphere valve 130 into a single three way valve. 5 Any standard air compressor may be used as the compressed air supply 120 for delivering pressurised air to the pressure valves 118 and 142. Similarly, any standard regulator 122 may be used to regulate the air pressure. If required, the liquid level determination means 148 may make use of optical, ultrasonic, vibration, magnetic, or any other level sensing technology. 10 Broadly, the above description relates to the capture of high temperature process liquids. In particular, the captured sample is then transported under pressure to a controlled chamber for analysis. The present application provides for a variation on the above technique. In large-scale processing plants, the liquid can be transported through an 15 intermediate storage vessel called a "header tank" prior to its main processing destination which is the thickener. These tanks have three main functions: they de-aerate the slurry; they slow down the process speed; and they filter out process surges. Preferably, the header tank is elevated several metres above the thickener. A generalised layout is shown in Figure 4, which is described in 20 greater detail, below. In practise, the Applicant generally mounts their equipment on a walkway on top of the thickener and uses a vacuum technique to capture a sample (as described above in relation to the "parent" invention). Once the liquid rises above approximately 70 C, the sample will start to boil due to the 25 reduced pressure. The above description depicts a technique which uses positive pressure to overcome the boiling problem. Under normal circumstances, the sample apparatus is 2 to 3 metres below the settling cylinder so the hot slurry has to be pumped vertically upwards. 30 The improvement which is subject of the present application is related to a variation of the previous technique. By accessing the header tank, gravity can - 16 be used to capture the sample. The principal of operation is shown in Figure 4 and is now described in greater detail. Whereas the previous embodiment of the invention operates on the principle of drawing a sample from the tank 106 (or "thickener"), the modified 5 process draws the sample prior to it entering the thickener. It is common industry practice to employ a "header tank" within the componentry employed on-site. The header tank is typically employed before the thickener; it filters out infeed product surges. With reference to Figure 4, the header tank is designated the reference 401. Product feed 402 (retaining the 10 alumina industry example employed previously) comprising a hot (e.g., 60-85 "C) and alkaline (e.g., pH -l4) liquid is pumped from its source (not shown) via a conduit into the header tank 401. A sample gate valve 403 beneath the header tank 401 is then opened and the product 402 flows, under gravity, towards the sample cylinder 404. 15 Initially, the sample drain valve 405 will be left open for a short time to ensure the new sample is representative of the process. The drain valve 405 is then closed and the sample 402 will flow into the sample cylinder 404. With the correct height detected via the probe 406, the gate valve 403 is closed. The supply line 407 providing fluid communication between the header 20 tank 401 and the sample cylinder 404 is fitted with a vent 409 to the atmosphere; this equalises the pressure differential resultant of having a hot liquid flow, under gravity, from the header tank 401 to the sample cylinder 404. Moreover, although preferably enclosed, the sample cylinder 404 itself has a vent, which equalises the pressure in the sample chamber. This is 25 important, as equalising the pressure to atmospheric prevents the hot (60-85 "C) liquid from boiling; boiling, of course, disturbs the sedimentation of the liquid and alters the resultant test data. In the example depicted, the volume of the sample cylinder 404 is 3.5 L. However, it will be appreciated that the illustrated invention is amenable to 30 many variations of this volume. Examination/analysis of the product 402 then takes place. The various components of the sampling apparatus are automatically controlled; the broad - 17 principle is depicted according to Figure 2. However, in respect of the present invention in which the various suction and pressure functionality is absent, it will be appreciated that the present process is relatively simplified. Accordingly, the sampling apparatus may be controlled by a sampling 5 controller 202. The sampling controller may be a processor which executes control instructions stored on a memory 204. The memory 204 may be of any type such as one or more RAM modules, one or more EPROMs and/or one or more magnetic or optical discs. The sampling controller 202 will also be provided with additional hardware and/or software as is desired. For example, 10 the sample controller 202 may be provided with input and output devices (e.g., mouse, keyboard, screens and/or speakers) to allow direct interaction with the controller 202 on-site. Alternatively (or additionally) the controller 202 may be provided with communication means such as a network interface controller (allowing access to 15 one or more networks) which allows remote control of the sampling apparatus, as well as the delivery of operational information on the apparatus (e.g., readings from the sampling of the fluid and/or any maintenance information on the apparatus itself) to a remote networked device. The sampling controller 202 is connected to each relevant component of 20 the sampling apparatus. If required the controller 202 may also be connected to an air compressor and/or an air regulator in order to monitor the status of these components and/or control their operation. Connection between the controller 202 and components will typically be wired, however if desired may be wireless 25 (e.g., bluetooth or an alternative wireless communication protocol). As discussed in greater detail below, the sampling controller 202 sends signals to and receives signals from each of the relevant components in order to operate the sampling apparatus. A method of obtaining a sample is now described. Referring to Figure 30 5, an overview of a method 500 involved in obtaining a sample in accordance with an embodiment of the invention is illustrated.

- 18 While the method 500 is described with specific reference to the sampling apparatus above, it will be appreciated that the method may also be used with alternative apparatus. Further, the process is described below as a fully automated method controlled by the sampling controller, e.g., 202, 5 however it would be equally possible to undertake at least some of the steps manually. In step 501 the sample cylinder 404 is charged with a sample volume of liquid from the header tank 401. In step 502, the sample volume of liquid 402 is analysed as required. 10 Sampling apparatus and methods are, however, often used (either manually or automatically) to obtain periodic samples of the liquid in order to maintain up to date information regarding the liquid. To allow for this continual periodic sampling the sampling apparatus is reset in step 503 to allow a new sample volume of the liquid 402 to be collected (i.e., by returning to step 501). 15 To charge the sample chamber, a simple gravity flow from the header tank 401 to the sample cylinder 404 occurs upon opening the sample gate valve 403. In the example application (the alumina industry) the sample will typically be analysed to determine the rate of sedimentation of the particles in 20 the liquid. This may be done, for example, by providing the sample cylinder 404 with a light source and complementarily placed photoelectric cell. When the sample volume of the liquid 402 is delivered, the particles suspended in the liquid will prevent the light from the light source from activating the photoelectric cell. As sedimentation occurs the sample volume will gradually 25 become clearer until the light can reach and activate the photoelectric cell. By measuring the time between delivery of the sample volume and activation of the photoelectric cell the rate of sedimentation of the sample volume can be calculated/extrapolated. In alternative applications the sample volume may, for example, be 30 analysed to determine chemical composition, chemical concentration, temperature, pH levels, density, turbidity, and/or any other relevant characteristic of the liquid/particles in the liquid.

- 19 To reset the sampling apparatus, the liquid 402 is drained under gravity into the thickener 410 via the sample drain valve 405. The pressure is equalised via the vent 409. When the system drains, it is desirable to remove everything from both the sample cylinder 404 and the supply line 407. The vent 408 5 ensures that the supply line 407 drains fully. Cleaning means (not shown) may then operate upon the internal surface of the sample cylinder 404. This may be in the form of a hot water shower, which drains either to the thickener 410 via the valve 405, or to an external waste outlet (not shown). However, as one skilled in the art will readily 1o appreciate, other cleansing methods, for instance, a soaking method, are applicable to the present invention. The particular materials and components used in the sampling apparatus will, of course, depend on the environment in which the apparatus is to be used. As noted above, one possible use of the apparatus is for sampling in the alumina 15 industry which provides particularly harsh conditions. In the alumina industry, the liquid is sodium hydroxide (NaOH) having a pH approaching 14, and is high temperature (up to 105 C). This liquid is both itself highly corrosive and produces a highly corrosive atmosphere. Further, the rapid corrosion in such an environment produce an effect called scaling - a build up on the surface of 20 materials submersed in the liquid. The scaling is extremely difficult to remove and as such the apparatus is designed in anticipation of scaling occurring. In order to ensure optimal gravity flow from the header tank 401 to the thickener 410, the header tank is preferably mounted between 3 and 10 m above the thickener. 25 All control sequencing is achieved through automatic electrical control, as described above. In the previous embodiment, the sample apparatus was filled using differential pressure with the sample intake point was below the sample cylinder. Now with gravity feed, the sample intake point is above the sample cylinder. 30 As this new process does not require capture and then transportation, the sample cylinder has also become the sample apparatus. This approach helps solve many other peripheral problems including maintenance, cleaning and the -20 transportation of hazardous chemicals under pressure. Such high temperature process applications are very prone to scale build up which is an ongoing site problem well known to those skilled in the relevant art. It will be appreciated that the latest embodiment of the invention has 5 several process advantages over the first embodiment. According to the first embodiment, practitioners normally use vacuum to capture a sample. Once the process goes above about 70 0 C the sample will start to boil due to the reduced pressure. The first embodiment of the invention then applies a positive pressure to overcome the boiling problem. However, no such issues are encountered 10 using the revised embodiment described above. It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention. 15

Claims (20)

1. A sampling apparatus for obtaining a sample volume of fluid from a bulk fluid, said apparatus comprising: 5 feed means for transporting said sample volume of fluid from said bulk fluid; a sample chamber for receiving said sample volume; sample means operatively associated with said sample chamber for analysing said sample volume of fluid; 10 drainage means for emptying said sample chamber; and control means to automate and control the interaction of said feed means with said sample chamber; and said sample chamber with said drainage means; wherein said bulk fluid is elevated with respect to said sample 15 chamber and said sample chamber is elevated with respect to said drainage means, said sample volume of fluid thereby transported from said bulk fluid to said drainage means via gravity flow; and wherein the sample chamber operates such that the liquid is not drawn by vacuum, thereby to facilitate operation in high temperature 20 environments without boiling the liquid.

2. An apparatus according to claim 1, wherein said sample chamber comprises venting means to equalise internal pressure within said chamber. 25

3. An apparatus according to claim 1, wherein said feed means comprise a valve selectively operable to allow a predetermined volume of said sample volume of fluid into said sample chamber. 30

4. An apparatus according to claim 1, wherein said drainage means comprise a valve selectively operable to evacuate, or substantially evacuate said sample chamber. - 22

5. An apparatus according to claim 1, wherein said sample chamber further comprises cleansing means associated with said control means, thereby to facilitate cleanout of said sample chamber following evacuation of said 5 sample chamber via said drainage means.

6. An apparatus according to claim 1, wherein said bulk fluid is sourced from a header tank. 10

7. An apparatus according to claim 1, adapted for use in with high temperature, corrosive liquids such as those characterising the alumina industry.

8. An apparatus according to claim 1, wherein said high temperature liquid is 15 between about 60 and 105 0 C and/or said liquid has a pH of about 1, or of about 14.

9. An apparatus according to claim 1, wherein said feed means is a conduit comprising a vent, thereby to substantially equalise the pressure within 20 said conduit.

10. A method for sampling a volume of fluid from a bulk fluid, said method comprising the steps of: transporting or inflowing said sample volume of fluid from said 25 bulk fluid to a sample chamber for receiving said sample volume; analysing said sample volume of fluid using sample means operatively associated with said sample chamber; emptying said sample chamber via a drain; wherein said sample means is operated via control means to automate and 30 control the inflow and emptying of said sample volume of fluid; wherein said bulk fluid is elevated with respect to said sample chamber and said sample chamber is elevated with respect to said drainage - 23 means, said sample volume of fluid thereby transported from said bulk fluid to said drainage means via gravity flow; and wherein the sample chamber operates such that the liquid is not drawn by vacuum, thereby to facilitate operation in high temperature 5 environments without boiling the liquid.

11. A method according to claim 10, further comprising the step of venting said sample chamber to equalise internal pressure within said chamber. 10

12. A method according to claim 10, wherein the step of transporting is associated with a valve selectively operable to allow a predetermined volume of said sample volume of fluid into said sample chamber.

13. A method according to claim 10, wherein said drain is associated with a 15 valve selectively operable to evacuate, or substantially evacuate said sample chamber.

14. A method according to claim 10, wherein said sample chamber further comprises cleansing means associated with said control means, thereby to 20 facilitate cleanout of said sample chamber following evacuation of said sample chamber via said drainage means.

15. A method according to claim 10, wherein said bulk fluid is sourced from a header tank. 25

16. A method according to claim 10, adapted for use in with high temperature, corrosive liquids such as those characterising the alumina industry.

17. A method according to claim 10, wherein said high temperature liquid is 30 between about 60 and 105 0 C and/or said liquid has a pH between about 1 and about 14. - 24

18. A method according to claim 10, wherein transportation takes place in a conduit comprising a vent, thereby to substantially equalise the pressure within said conduit. 5

19. A sample, when taken from a volume of bulk fluid by a method as defined according to any one of claims 10 to 18.

20. A sampling apparatus according to claim 1; a method according to claim 10 10; or a sample according to claim 19, substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples. 15 Dated this 2 7 th day of October 2014 Shelston IP Attorneys for: Oscillation Pty Ltd