Abstract:
A servo-electric actuated sampler can draw samples of fuel liquid from an operating main line. The sampler can run in a fast-loop process whereby liquid is drawn into the sampling system and past an actuated sampler and then out of the system back into main. The system main run a short loop whereby the main fast-flow is restricted, and the actuator and sampler are isolated from the main line flow. When isolated, the sampler discharges liquid into sampling cans. The servo-electric actuator requires a monitored amount of power to draw and discharge fluids. Monitoring of the power requirements of the servo-electric sampler can reveal the status and reliability of the system.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present application includes subject matter disclosed in and claims priority to a provisional application entitled “Servo-Electric Controlled Auto Sampler System” filed May 6, 2016 and assigned Ser. No. 62/332,935 describing an invention made by the present inventor which provisional is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0002]    The present invention relates to the field of measuring and testing fluid and more particularly, the present invention relates to controlled sample testing of fluid flow. 
       2. Description of Related Prior Art 
       [0003]    To comply with Federal Energy Regulatory Commission (FERC) rules and in accordance with the American Petroleum institute (API), it is known and required to take product samples of—historically, for every 80 feet parcel of flowing product. For instance, if there is a flow of 20 feet per second, a sample most be drawn every 4 seconds. Multiple devices designed to accomplish this grabbing of samples from flowing petroleum products. Typical samples may be drawn of 10 cubic centimeters (cc). When multiple samples are taken in a single grabber or sampler, multiple receivers may be used, one for each specific time period. Each sample take can also be known as a grab or bite or sample. For crude oil sampling, die recent issuance of API 8.2 MPMS third edition (2015) determines sampling frequency by using a statistical error basis. More specifically, a minimum of 9064 sample grabs per batch of flowing product gives a desired maximum 0.0.1 margin of error. With variance of batch-size and a fixed volume of the receiver(s), the ability to vary both the grab size and frequency is advantageous when a minimum and/or maximum, collected volume is desired. For instance sampling a 906,400 gallon batch into 4 gallon (15,141 cc) receiver, it is required to collect one 1.67 cc sample per every 100 gallons. Now if 8 gallons was required to be collected, a grab size of 3.34 cc every 100 gallons OR 1.67cc sample per every 50 gallons would meet the requirement. 
         [0004]    As known in the prior art, spring-loaded piston or pneumatic pistons are often manually adjusted to set the sample grab size. 
         [0005]    Present day pump volume regulators include pneumatic piston pumps and spring-loaded volume regulators. For instance, a present day prior art volume analyzer can be driven by a pneumatic piston pump. A bite checker or volume analyzer monitors samples and pump volume. The device includes a single inlet and a single outlet functioning at atmospheric or low pressure. Similarly, overflow purge must travel into a low pressure, or atmospheric pressure, drain pan, tank or sump. Given that the system is pneumatically driven, the system requires a separate pneumatic driver to power the piston pump. Furthermore, the pneumatic driven sampler also relies on air pressure actuation of air valves. Pneumatic driven samplers provide no active control of the speed of the pump nor control of the volume. In effect, the device signals pump actuation and moves through an entire stroke at a speed determined by the power provided by the pneumatic system and friction/resistance therein. The power provided by the pneumatic system can vary based on processing conditions and through the stroke. An optional manual positioned-limited-switch to indicate the end of stroke may also be used to show position of stroke, but this also suffers the flaw of manual oversight requirement. 
         [0006]    Other current volume regulators include spring-loaded volume regulators. Spring-loaded volume regulators typically me an atmospheric or low pressure drain. A drain typically leads to a remote container which may or may not be under atmospheric pressure, for proper disposition (e.g. to a tank, to be injected back into pipe line, sent to a flare etc.). Given the spring-loaded nature of the system, sample size is limited to a very small size and a small range. In order to achieve a larger volume sample size with a spring-loaded volume regulator, additional volume regulators must be used. Spring-loaded volume regulators rely on process pressure to compress the spring—and overcome friction to draw the low sample and also rely on gravity and the energy consequently stored in the spring for discharging of the sample down into a can. One drawback of spring-loaded volume regulators is the typical use of a 3-way valve which can close suddenly and deadhead the system in a fast loop. In order to achieve required flow rates and volume, sometimes these valves on the discharge side will be required to close swiftly and thereby interrupt the product flow thereby causing a jolt in the product flow to deadhead the system. Product in the sampler can also stagnate and therefore require periodic purging to clear out the system. Purging is achieved by multiple cycling of the valve and regulator several times to clear out the system. Similar to pneumatic systems, overflow and purge is placed into a sump or drain at atmospheric or low pressure. Spring-loaded volume regulators can only dump to atmospheric or low pressure vessels, typically under 15 pounds per square inch (psi), and depend on spring force, gravity, the viscosity of the liquid, and restriction of the plumbing. Spring-loaded volume regulators also suffer from the lack of any active control of speed or volume. Speed in such systems is determined by opening of the 3-way valve and the pressure from the flow input. Spring-loaded, systems also suffer from friction that can develop in the system and prevent or limit the discharge and thereby affect sampling. 
         [0007]    Therefore, there exists a need for controlled sampling. 
         [0008]    It is therefore a primary object of the present invention to provide regulated sampling of flow. 
         [0009]    It is another object of the present invention to provide a servo controlled variable draw sampler. 
         [0010]    It is yet a further object of the present invention to provide a measured draw sample of product flow. 
         [0011]    It is yet a further object of the present invention to provide controlled injection of sampling cans. 
         [0012]    It is yet another object of the present invention to monitor sample draws. 
         [0013]    These and other objects of the present invention will become apparent to those skilled in the art as the description thereof proceeds. 
       SUMMARY OF THE INVENTION 
       [0014]    The auto sampler system of the present invention utilizes a servo-electric pump for drawing samples of flow and moving such samples into sampling cans. The auto sampler of the present invention can work on a fast loop off of a main. By allowing the entire fast loop flow to enter and exit the sampler, this ensures a fresh representative sample is available at all times. The auto sampler is adaptable for direct crude sampling or direct pipeline draw, and can handle constant pressure applications such as natural gas liquids (NGL). By using a servo-electric sample pump, the servo can drive a desired speed and position to get the particular sample required. The servo-electric sample pump can be scalable for varied volumes and pressures of flow to produce desired sample sizes. Furthermore, the servo-electric sample pump has the advantage of allowing a constant velocity steady grab that can be paced to meter as is necessary, at a constant rate if required. Furthermore, the servo can be programmed for predefined index grabs of the same or varied grab sizes. 
         [0015]    By using the servo, the system can determine how much volume is being drawn, and the viscosity of the inflow based on the amperage required to drive the servo-electric. The auto sampler of the present invention can integrate existing programmable logic controllers. The valving in the auto sampler of the present invention can use any various valving, including pneumatic hydraulic, or electric, operated valving to coordinate with the servo-electric pump sampling. In addition, to calibrate or provide redundancy to the servo sampling, weigh scales can be provided under sampling cans to verify weight of collection samples. Monitoring of power needed to drive the hydraulic arm and/or servo-electric actuator can help understand operation of system, potential issue or problems with connections or components, etc. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The present invention will be described with greater specificity and clarity with reference to the following drawings, in which: 
           [0017]      FIG. 1  illustrates a prior art pneumatic actuated sampler. 
           [0018]      FIG. 2  illustrates a prior art spring actuated sampler. 
           [0019]      FIG. 3  illustrates a diagram of a sample system embodiment of the present invention. 
           [0020]      FIG. 4  illustrates a diagram of a working sampler system embodiment of the present invention. 
           [0021]      FIG. 5A and 5B  demonstrate the electric actuator in closed and open position, respectively. 
           [0022]      FIG. 6  demonstrates a diagram of actuator arm distance in a grab sequence. 
           [0023]      FIG. 7A  demonstrates the last flow process diagram of an embodiment of the present invention. 
           [0024]      FIG. 7B  demonstrates the short flow process diagram of an embodiment of the present invention as shown in  FIG. 7A . 
           [0025]      FIG. 7C  graphs the grab volume during the sampling taken in process demonstrated during fast flow and short flows of  FIGS. 7A and 7B . 
           [0026]      FIG. 8  demonstrates the fast flow process diagram of an embodiment of the present invention. 
           [0027]      FIG. 9  graphs the power requirement during sampling of a diagnostic monitor of an embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0028]    The present invention includes a novel servo-electric sampling system. Speed and distance of the actuated arm can be monitored and measured, along with the power to drive the actuated arm to draw and dump samples. The actuator can be remotely controlled and programmed to provide specified volumes, timing, and speed of sampling. Additionally, the new servo-electric sampling can include extremely slow draws of samples that are controlled. Feedback and diagnostic systems can signal, report, or otherwise indicate a problem with the system. Furthermore, the system can include additional programming to compensate if an error or issue is detected, for instance a blocked line, malfunctioning can valve, etc. and can be bypassed, repaired, or compensated as needed. 
         [0029]    One aspect of the present invention is the use of a programmable servo electric actuated grabber that can take similar and/or controlled volume varied sample sizes in predetermined or programmable sequences. A linear servo-driven grabber can distinguish variable volume timing and speed for sample grabbing. For instance, if a sample is required, the servo actuator can run at a much slower and more constant pace to draw a sample. This is especially useful when slow grabs or infrequent grabs, or multiple grabs can be drawn together to pull a sample. In such an instance, the servo can draw a long draw (e.g. 20-second draw) into linear actuator, and is not restricted to the speed size or timing of prior art spring-loaded and pneumatic piston bites. For example, the servo-electric drawn actuator can pull at a set rate of one cubic centimeter per second for 50 seconds combining samples for a single dump at a standard constant rate. In such example, a 50 cc sample is obtained. Another feature of the present invention is the programmable sample sizing and speed. Servo-electric pump can be programmed via remote connection to modify sample grabs based on requirements as time goes. 
         [0030]    A typical pipeline includes 20-40 inch main lines that are under lower (less than 100 psi) pressure. However, depending on the product through main line, pressures can range from 30 psi to 2000 psi. The servo electric drawn sampling system of the present invention can currently handle low and very high pressures as high as and beyond 1000 psi and maybe soon constructed to handle pressure in excess of 2000 psi. Furthermore, the system can detect failures of the sampling if, for instance, pressures are beyond capacity or any other failure in the system. This may provide immediate indication that the actuator is not working. Failure may be due to a variety of reasons, such as a difference in required draw force to pull, or failure to draw sample. This can be indicated and communicated to a controller to immediately indicate a problem with the system. This problem can be diagnosed on the fly to correct or repair system, without losing excessive sampling time or opportunities on the sampler. This contrasts prior art systems whereby manual overview for weigh scale on receivers is required to diagnose problems in the system. 
         [0031]    Referring to prior art systems of  FIG. 1  and  FIG. 2 , a pneumatic and spring actuator are shown. Pneumatic power source  1  is provided along air/gas conduit  2 . Inflow  8  allows fluid, from main line to pass under actuator  3 . Pneumatic actuator  3  drives rod  4  to push or pull piston  5  to move seal  6  within system to dump or take sample in cavity  7 . Similarly, in  FIG. 2 , spring provides power to drive piston. 
         [0032]    Referring to  FIG. 3 , actuator  1  provides draw or pull (system pressure is present, usually vacuum conditions are not experienced) to allow flow running past actuator to draw into hydraulic cylinder  3 . Actuator  1  can then force/push sample in actuator through linear actuator into sample receivers  4 . 
         [0033]    Referring to  FIG. 4 , the typical grab sequence is illustrated in a fast loop process with at least one, and as many as four or more, sampling receiver(s) (four sampling receivers shown). Flow moves in through fast loop process source  100  from main (not shown) and out exit  199  back into main. Additionally, drainage may occur around top loop  110 , into drip pan  111 , or drain  190 . On a typical grab sequence, actuator  102  is activated through electrical power in  182 , with electric charge, to draw servo-electric pump arm  103  up to pull sample into sample space  104 . Once the sample is taken, the fast loop is closed as three-way control valve  105  is closed to bypass flow through a short loop whereby fluid is drawn, and directed directly from control valve to exit  199 . 
         [0034]    While control valve is closed (short loop), sampling cans are isolated from main line. At this time, any one of sampling valves  121 , 122 ,  123 ,  124  can open to allow sample to flow into one of receivers  131 ,  132 ,  133 ,  134 , respectively. To dump sample, servo draws actuated arm  1 - 5  down to push sample out of sample space  104  through line  140  into a can through one of the can valves that may be opened. Next can valve  121  is closed and flow resumes through horizontal draw line  140  until control valve  105  is then drawn back into original position to allow fast loop continue to flow through process tubing  150 . Because product runs continuously through the sampler during last flow (past control valve  105 , can valves and through top loop in process tubing  150  out exit  199 ), no purge cycle is required as the flow of product itself constantly purges sampling system. Power is provided along power line  182  to supply actuator  101 . Actuator  101  drives rod or arm  115  to move seal  103  and modify sample space  104  to draw or purge sample. Drip pan  111  may be included for over flow or fluid or vapor, etc. Scales  161 ,  162 ,  163 , and  164  may be used with respective cans to provide a backup measurement of the weight of canister content. Vent  162  may be included to provide for gases to escape during fast flow process. 
         [0035]    Considering electric actuated ball valves and “large” 50 cc grab sizes, on a regular draw cycle, it is contemplated that a normal complete cycle time may be approximately 16 seconds whereby the sequence follows through the following; Begins on fast loop a draw cylinder pump (here an estimated 50 cc) acts for two seconds. During fast loop, control valve  105  is open. Next control valve  105  is bypassed 90 degrees for 11 seconds to run fluid in short loop. Can valve  121  opens to can  131  for 3 seconds. Next, cylinder pump  101  actuates arm  115  down to inject or push sample through can valve  121  into can for 2 seconds. Can valve  121  then closes 3 seconds. For the last remaining 3 seconds, control valve  105  returns to normal position to allow fast flow through in standard fashion. In a preferred embodiment, fast loop flows through a ball valve to a 3-way actuated control valve in the inflow process. Flow is run through process tubing  150  into servo actuator  101  or through system to out loop  199  or drain  190 . Each of the can samplers is actuated through a 3-way actuated can valve to allow the receiver (or can) access to the injected flow as it is injected via servo pump. The electro server provides a metered sample grabber or actuated arm to draw and push sample flow. 
         [0036]    Referring now to  FIGS. 5A and 5B , servo-electric actuator is shown as linear device for drawing samples. A preferred electric actuator is that provided by EXLAR particularly the EL30series. The preferred servo drive is provided by A-M-C. Electric actuator draws hydraulic cylinder to function as driven piston pump. Electric actuator  101  is connected via coupling to hydraulic cylinder  108 . Actuator  101  draws rod  115  along coupling to move hydraulic cylinder  108 . An anti-rotation device  107  may also be used to ensure that actuator functions properly. The anti-rotation device prevents the lead screw from turning with the internal motorized nut to ensure proper operation of the linear actuator. As seen in the example shown in graph of  FIG. 6 , extension distance is shown on the vertical axis and time is shown on the horizontal axis. At time zero, grab starts where servo extension is initially at 6 inches (closed) and over 1.25 seconds draws up to open at approximately 2⅛th inch, to pull in sample. For approximately a quarter of a second, the servo actuator is open to allow waiting for input during dwell time. After dwell time, servo draws down from 2⅛th inch to 6 inches to purge and inject flow sample into receiver can. The linear actuator has returned to home position. 
         [0037]    As can be seen on  FIG. 7A-7C , a typical grab sequence  300  with a single grab per cycle is shown. It is estimated that a single grab per cycle is applicable when draw times allow for servo actuator to act to pull requisite sample. As can be seen green line in  FIG. 7A , when 3-way control valve  305  is open for sampling system, flow  320  draws through process line  350  past servo actuator  301 . Linear actuator  302  and servo controlled actuator  302  draw sample into metered grab sampler  304 . One specific feature of the present invention includes the continued flow along  320  in from main  310  and out through exit back to main  399 , while going past servo actuator  301  and past sampling can valve  321  to allow flow to continue through system around in counter-clockwise. In  FIG. 7A , system is considered that fast loop as main flow  320  runs in and out of the system though main process tubing  350 . When 3-way control valve  305  is opened, the fast loop is opened to allow flow to be directed through the sampler from the fast loop. Note also this purges the sampler every time 3-way control valve  305  is opened for fast loop sampling. As seen in  FIG. 7B , at such time as sample is necessary to be drawn into actuator for sampling in grabber, 3-way control valve  305  is closed and last loop is restricted. Flow  390  continues in the from main source  310  bypassing the sampler and out exit  399 . When 3-way control valve  305  is closed, servo actuated grabber  301  can purge or inject flow via flow line  320  through opened 3-way can valve  321  into sampling can  331 . 
         [0038]    As can be seen in  FIG. 7C , the flow of a simple one grab per cycle is shown. Referring to  FIG. 7C , on the vertical axis is volume, on the horizontal axis is time. Line  345  demonstrates the volume in the grab cylinder and the section  342  demonstrates the volume of sample in the container. Each sample grab is shown as a diagonal rising line over time as a grab  340  is drawn into cylinder. Horizontal lines  341  on line  345  demonstrate when 3-way control valve is closed to allow injection into receiver, container, or can (any receptacle container capable of holding sampled material suffices for “can” herein. Note: The words receiver and can are both used in this disclosure, and a receiver can allude to any receiving device, and a “can” can refer to a holding device, in which a “can” can act as a receiver, and a receiver can be comprised of a “can”). This is also known as dump to receiver. In such way, receiver can volume can include predetermined amounts of sample, over time, for testing. 
         [0039]    If sample grab rates required are too quick or too short to allow time for the valve actuation, the sample pump cylinder can be used to continually draw sample at a specific pace. Once a specific number, or required volume, or required number of samples, is in actuator  301 , the system can dump several grabs together at once into a single can, e.g.  331 . As shown in  FIG. 7A , flow  350  includes draw into servo actuated grabber  301  for multiple grabs during fast loop flow  300 . Arm  302  is drawn up partially with each grab sequence. As shown in  FIG. 7B , 3-way control valve  305  is closed, ending fast loop, as flow  351  enters  310  and directly exits  390 . Electro servo actuator  301  can thereby dump through 3-way can valve  321  into container  331 . 
         [0040]    As shown in diagram of  FIG. 8 , volume of grab is on the vertical access and time on the horizontal access, the diagonal line  445  indicates the multiple grabs that are collected in the cylinder at once and the horizontal line  446  shows when 3-way control valve is closed to allow dumping into receiver can. Receiver container volume  447  is demonstrated in area below the line  445 . 
         [0041]    One significant feature of the servo-electric actuated auto sampling is the ability for diagnosis and programmable control of sampling for consistent volume requirements, or varied flow viscosity or material. As shown in diagram on  FIG. 9 , modelled is a servo drive controller as it draws actuator to grab a sample. Diagnostic capability graph  500  shows extension distance is on the vertical axis where grab in cylinder is at home position  501  and draws into retracted grab position  502 . Motor current  503  (or power required) demonstrates the amount of power required to move actuated linear actuator from home position  501 to grab position  502 . The amount of current for power required to draw actuator pump from home to retracted grab position tells us many things about the viscosity of the material drawn for sampling, any defects in the actuator pump, defects in the associated valving or plumbing or the amount of volume drawn. 
         [0042]    When it is known how much and the characteristic shape of power curve over time is used to operate linear actuator, any differentiation in magnitude and characteristic of power required to operate grabber will tell us that something has changed in the system. Typically the change will be due to some sort of defect in the sampling system. 
         [0043]    Referring again to  FIG. 9 , at time “0” actuator position  510  is in home position  501  and pump is drawn via pump position indicator  510  to retracted grab position  502 . As can be seen in line  503 , amperage or power required in home position  501  is at a minimum. When actuator is drawn into retracted grab position  502  the amount of current or power rises substantially to draw back linear actuator (following amperage line  503 ). The maximum level at which amperage reaches upon full draw of actuator demonstrates the maximum power required to make the draw. The area under the power fine  503  tells us the total power required to make a specific draw. Between grabs if the amount of power required to make any particular grab is different from the others or if over time the amount of power required to make any grab increases (or decreases), this can tell us if there is either a defect in the system, clogged line change in flow material, etc. 
         [0044]    When actuator is in retracted grab position  502  (follow position line  510 ), the power required to maintain that position as shown in amperage line  503  is fairly constant. During dump (follow line  511 ), or pump to a receiver can at trigger input  520 , power required decreases substantially, or is drawn into the reverse direction (below zero as indicated, at amperage line lower section  531 ), to power the dumping in opposite direction as actuator is forced to move arm down back into home position. Similarly, the amount of power required in the reverse direction can tell us about the amount of material grab in the sample as well as the viscosity of the material, as well as any defects along the dumping line system. The controller can be configured to monitor the electric current of a normal sequence, to define magnitude and shape of changes, and thereby determine whether or not the electric current profile over-time indicates any physical change in the system. By demonstrating a change in the amount of power required for the servo-electric to actuate the grabber, problems can be diagnosed remotely via message signal from the servo-electric to some type of controller that thereby communicates on-site to a monitor or off-site via electronic communications. 
         [0045]    An additional feature is that the servo-electric actuator grab can allow for an expanded system with varied bites taken over longer periods. Whereas prior art samples are typically collected every 6 hours over the 24-hour day, an expanded electro servo driven auto sampler can include an expanded system that can reduce the number of times that samples must be collected. For instance, in expanded system of the present invention with multiple containers for programmed specified samples, the number of samples removed manually from the system can be reduced to once per day, etc., to comply with FERC and API requirements. 
         [0046]    Optionally, weigh scales can be used to measure and determine the amount of sample taken in the sampling containers or cans. These can be used to determine failure if not enough weight is detected in a container and thereby alert of failure. The weigh scale is optional because the servo-electric driven actuator can include feedback, as discussed, in the power required to draw the sampler actuator, and thereby determine the volume amount viscosity etc. of sampling without need for a weigh scale. The present invention with the monitored servo electric driven sampler can detect the amount of sample without weigh scales. Weigh scales can be used as a redundancy for determining issues or failures, in the sampling system. 
         [0047]    An additional feature of the servo-electric, drawn auto sampling system is the ability to power a draw or pull of sample in addition to the push or injection into can or dump into can at varied pressures. Prior art systems are built for low pressure (under 100 psi) typically at atmosphere. For instance, when natural gas liquids (NGLs) consist of compressed gas, samples need to be drawn under pressure. An advantage of the electro mechanical actuator is that the force of piston into the can can be done under a constant pressure or under varied pressure systems. 
         [0048]    The servo-electric driven actuator provides consistent and constant feedback of the speed of the draw and power required. This gives an indication of flow data remotely via electronic communications. Using the electro mechanical driven system, mote information can be drawn about the performance of the system as well as the features of the sample drawn. Multiple different product flows through pipe can be drawn through the fast flow system with the same actuator of the present invention programmed to handle varied viscosities and material sample.