Metering Check Valve for Fluid Injection

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This is a non-provisional of U.S. Provisional Patent Application Ser. No. 63/671,562, filed Jul. 15, 2024, to which priority is claimed, and which is incorporated herein by reference.

FIELD OF THE INVENTION

This application relates to systems and methods for a volumetric metering of fluids, and more specifically to a check valve that combines the functions of an inline check valve with the capabilities of a rotometer for measuring the flow rate of a fluid as it passes through the valve.

INTRODUCTION

In many processes there is a need to deliver small amounts of a fluid whether it is a gas or liquid into another stream of gas or liquid (i.e., a process). Although the concepts discussed in this disclosure are described in connection with the operations of the upstream oil & gas industry, the same principles apply in many other situations.

In the production of natural gas and crude oil, it is often necessary to inject a small quantity of chemicals, catalyst, or other materials into a production stream. Some examples include the delivery of corrosion inhibitors, hydrogen sulfide scavengers, methane hydrate suppressors and the like. The production stream may be natural gas, distillates, liquid petroleum or a mixture of gas and liquid.

Because the injected/added fluids may be relatively expensive, it is important to deliver a sufficient quantity of product but not an excessive quantity. These products are typically injected at very low rates compared to the quantity of the production stream. Volumes as low as one quart per day to tens to hundreds of quarts per day are not uncommon. Because the production stream is flowing more-or-less continuously, the associated fluid injection must be done more-or-less continuously into the production stream so the added fluid does not end up in a small volume of the production stream thereby starving the bulk of the production stream and overtreating a very small part of it. It is a tribute to the industry that small capacity solar powered reciprocating pumps with inline check valves have become quite efficient and are now ubiquitous for this purpose.

Currently there are numerous approaches to monitoring and controlling the injection rate of the pump. One approach involves measuring or predicting the quantity of liquid in a supply tank. This approach is difficult and imprecise, mainly because the supply tank is very large compared to the quantity of injected fluid or chemical in each pump cycle and any inaccuracy in supply tank measurement massively exceeds pump deliverability so any attempt at accurately measuring the delivered volume from the pump is very difficult. Other techniques involve stroke counting. It is assumed that each cycle of the reciprocating pump piston will deliver a consistent, known volume of liquid. By monitoring the cycles or number of strokes of the pump you can assume this calculated volume has been delivered to the intended point in the process. There are many issues with this concept—the supply of fluid to and from the pump may be blocked, the pump can become ‘air-locked,’ and fluid is unable to enter the piston chamber through the inlet check valve to be discharged into the process, for example. The pump shaft can become uncoupled from the motor and even though the motor is turning or stroking, the pump chamber does not fill and deliver the fluid. The seals around the pump piston shaft can leak and fluid is discharged on the ground or atmosphere instead of being delivered to the desired point. Thus, there is a need for further approaches to monitoring and controlling the injection rate of the pump.

SUMMARY

Disclosed herein is a valve configured to measure a volume of fluid delivered from a pump, wherein the pump comprises a fluid chamber with a reciprocating piston that moves fluid in and out of the fluid chamber and inlet and outlet inline check valves to/from the chamber. The outlet valve may comprise: an inlet configured to receive fluid from the pump, a valve body, a float configured to isolate the inlet from the valve body during a suction stroke of the piston and to open during a delivery stroke of the piston to allow fluid to flow through the valve body, and a transducer configured to measure a distance the float travels as the fluid flows through the valve body, wherein the distance is indicative of a volume of fluid flowing through the valve. According to some embodiments, the valve further comprises a connection configured to connect the valve body to the pump. According to some embodiments, the float comprises a valve plug and a stem. According to some embodiments, the valve body comprises a plug seat, and wherein the valve plug is configured to form a sealing engagement with the plug seat during the suction stroke of the piston. According to some embodiments, the valve body comprises a sleeve comprising an inner wall conical section. According to some embodiments, the valve plug travels within the inner wall conical section as fluid flows through the valve body. According to some embodiments, the valve is configured such that travel of the valve plug within the conical section creates a variable area orifice for flow of fluid through the valve body. According to some embodiments, the stem comprises a magnetic material on at least a portion of the stem. According to some embodiments, the transducer comprises at least one coil. According to some embodiments, the at least one coil comprises a generator coil configured to generate an electromagnetic field within the valve. According to some embodiments, the valve is configured so that as the float moves, the magnetic material creates a time-varying change in the electromagnetic field. According to some embodiments, the transducer further comprises a sense coil configured so that the time-varying change induces a current in the sense coil. According to some embodiments, the current in the sense coil is indicative of the volume of fluid delivered from a pump. According to some embodiments, the transducer comprises a Hall effect sensor or a linear variable differential transformer (LVDT).

Also disclosed herein is a system for measuring a volume of fluid delivered from a pump, wherein the pump comprises a fluid chamber with a reciprocating piston that moves fluid in and out of the fluid chamber and inlet and outlet inline check valves to/from the chamber the system comprising: a valve comprising: an inlet configured to receive fluid from the pump, a valve body, a float configured to isolate the inlet from the valve body during a suction stroke of the piston and to open during a delivery stroke of the piston to allow fluid to flow through the valve body, and a transducer configured to measure a distance the float travels as the fluid flows through the valve body, wherein the distance is indicative of a volume of fluid flowing through the valve, and control circuitry configured to receive data from the transducer and determine the volume of fluid delivered by the pump based on the data. According to some embodiments, determining the volume of fluid comprises determining a data set indicative of the travel of the float as a function of time. According to some embodiments, determining the volume of fluid further comprises integrating the data set. Methods of using the valves and other systems described herein are also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an embodiment of a system for providing a fluid to a pipeline.

FIG. 2 shows the operation of a reciprocating pump.

FIG. 3 shows an embodiment of a flow meter check valve.

FIG. 4 shows a plot of displacement of a float in a flow meter check valve as a function of time.

FIG. 5 shows an embodiment of a workflow for calibrating a flow meter check valve.

DETAILED DESCRIPTION

Aspects of this disclosure relate to systems and methods for overcoming the problems described above. Specifically, the disclosure relates to a flow meter check valve that can be connected to the discharge side of a reciprocating action pump to monitor, analyze, calculate and control the flow of fluid through the pump. It should be noted that the exact mode of operation of the fluid delivery systems and methods described herein are subject to considerable variation. They may use the operating approach of any of those disclosed in U.S. Pat. Nos. 4,322,972; 4,538,445; 4,856,343; 5,199,307; 7,263,448, 11,644,019 and the like, or may be used independent of aspects described in those patents.

FIG. 1 illustrates an embodiment of a fluid delivery system 100 wherein a fluid or composition in a tank 102 is delivered to a pipeline 104 which may carry a stream of produced fluid, for example, or may be configured for injection into a well. Oil field chemical tanks are typically cylindrical and horizontally positioned as shown in FIG. 1, but this is a matter of custom and convenience.

The tank 102 has a bottom outlet 106 which is typically an externally threaded nipple (not shown) having a manual shut off valve (not shown) threaded onto the nipple. The outlet 106 is connected to a valve 108, which may comprise an electrically actuated valve operator 110. Alternatively (or additionally) the valve 108 may be operated manually. The system 100 comprises a column 112, which may be configured as a measuring tube or sight glass. The column 112 is connected via a fitment 114. A pressure gauge 116 may be inserted into the fitment 114 and configured to measure the height of liquid in the column 112. As the column is vented back to the tank 102 via conduit 118, the height of liquid in the column is indicative of the height (and thus, volume) of liquid in the tank 102. In the drawing, the dashed lines 120 and 122 represent the fluid levels in the column and in the tank, respectively. Thus, data from the pressure gauge 116 may be used to indicate the inventory of the chemical (or formulation) contained within the tank. The data from the pressure gauge may also be used to calibrate the volumetric measurements of the liquid delivered, as explained further below.

The system 100 comprises a pump 124, which may be a reciprocating pump.

Embodiments of the pump 124 comprise a flow meter check valve 126, which is described in more detail below. Here it should be mentioned that the flow meter check valve 126 is configured to provide real-time measurements of the volume of fluid that is delivered with each discharge stroke of the pump 124.

Embodiments of the system 100 comprise a control unit 128 that can be configured to control various operations of the system. The control unit may comprise a Human-Machine Interface (HMI). An HMI is a user interface or dashboard that connects a person to a machine, system, or device. While the term can technically be applied to any screen that allows a user to interact with a device, HMI is most commonly used in the context of an industrial process and/or may be comprised of buttons, keys, an LCD display, etc. The control unit comprises control circuitry that may be embodied as one or more microcontrollers, microprocessors, central processing units (CPUs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), etc. The control circuitry may be configured to execute code, causing the control unit to perform various aspects of the functionality described below. The control unit may comprise storage media, which may generally be any type of computer readable media, for example, solid state memory. The storage media may comprise computer code, which, when executed by the control circuitry, configures the control unit to perform the functions described herein. The control unit 128 may be configured to communicate commands and/or data between various components of the system via communications paths 130. The communications paths may comprise one or more data busses, wires, cabling, etc., as is known in the art, and may be configured to communicate according to communications protocols known in the art. According to some embodiments, the control unit 128 may comprise a telemetry unit 132, which may be configured to communicate data and/or commands between the control unit and a remote location. The telemetry unit may be configured to communicate via a cellular network, a satellite network, or the like. Though not shown in the drawing, the system may further comprise a power source/system, which may typically comprise one or more batteries and/or solar panels, windmills, or the like, for remote deployment of the system. The power system provides power source/system for the pump, the control unit, the sensors and actuators, and the like.

As mentioned above, aspects of the disclosure relate to a flow meter check valve that can be connected to the discharge side of a reciprocating pump. FIG. 2 illustrates aspects of the operation of a typical reciprocating pump, which will be familiar to a person of skill in the art. The pump includes an inlet check valve (also referred to as a suction valve), which comprises an inlet check float, and an outlet check valve (also referred to as a delivery valve), which comprises an outlet check float. During the suction stroke of the pump's piston, the inlet check valve is open and the outlet check valve float closes off the outlet check valve, allowing the piston's action to draw fluid into the chamber. During the compression stroke (also referred to as the delivery stroke), the outlet check valve opens to allow the fluid to be expelled from the chamber and the inlet check valve float closes off the inlet check valve to prevent fluid from flowing backwards. In the illustration, both the inlet check valve float and the outlet check valve float are illustrated as balls. However, many other configurations and shapes of check valve floats are known in the art. Some embodiments of check valves may include springs (not shown) to bias the movement of the check valve floats, as is known in the art. It should be noted that the flow meter check valves described herein may be used with pumps having other configurations than the one illustrated. For example, some pumps include a diaphragm that isolates the chamber from the piston. Embodiments of the disclosed flow meter check valves may be used with any pump configuration of a reciprocating nature that features a suction cycle and a delivery cycle or of a continuous delivery system that utilizes an inline check valve to prevent backflow of fluid from the receiving process.

FIG. 3 illustrates an embodiment of a flow meter check valve 300. According to some embodiments, the flow meter check valve may replace a conventional outlet check valve of a conventional pump. The flow meter check valve comprises a valve body 301 comprising a main valve body housing 302, which includes an inlet, which may comprise a process connection 304 for connecting to the pump. According to some embodiments, the process connection 304 may be a 0.25-inch MNPT connection, for example. The main valve body housing 302 is configured to connect to a sensing element 306, for example, via another process connection 308, the intention of which is to firmly hold the sensing element in relation to the valve body. The sensing element may be configured with one or more generator coils 307 and one or more sense coils 309, the function of which will be described below. According to some embodiments, the sensing element may be configured to slip onto the valve body housing 302. According to some embodiments, the sensing element can be replaced, for example in the cases of failure, without having to replace the rest of the valve/meter.

The main valve body housing 302 may also be configured to connect to an outlet process connection/stem guide assembly 310, for example, via another process connection 312. The annulus 311 of the outlet process connection/stem guide assembly 310 may operate as a stem guide, as described further below. The outlet process connection/stem guide assembly 310 may comprise threads or other process connection 313 for connecting to downstream piping and equipment. The threads 313 may comprise a 0.25-inch FNPT connection, for example. In the illustrated embodiment a gasket 314 is situated between the main valve body and the outlet process connection.

The main valve body contains a flow element sleeve 316, which is configured to contain a float 318. The flow element sleeve inner wall comprises a conical section 317, the importance of which will be discussed below. The float 318 comprises a valve plug body 320, and a stem 322, in the illustrated embodiment. According to some embodiments, the stem 322 is made of a nonferrous material, such as a polymeric material, ceramic, titanium, or the like. A magnetic marker 324 is configured upon or within the stem of the float. The magnetic marker may or may not comprise a ferrous material, such as iron, or an iron compound infused into or otherwise adhered to the stem. According to other embodiments the entire stem may be magnetically active and may act as the “marker,” i.e., the linear movement of the entire stem is measured. A spring 326 may be configured upon the stem.

During the suction stroke of the pump's piston, the valve plug body 320 is maintained in a plug seat 328 of the main valve body and/or the flow element sleeve. In the illustrated embodiment, a plug seat gasket 330 is provided to prevent backflow of fluid during the suction stroke. During the compression/delivery stroke of the pump, fluid flows through the check valve 300 in the direction indicated in the drawing and pushes the float body upward. This forms a gap between the inner wall 319 of the flow element sleeve and the valve plug body 320. Since the inner wall 319 of the flow element sleeve is conical, the area of that gap increases as the valve plug body rises higher in the flow element sleeve, providing a variable area orifice for the flow of fluid through the check valve. The height that the valve plug body rises during the compression/delivery stroke is a function of the tension of the spring 326 (which is ideally constant), the density and viscosity of the fluid being delivered, and the volumetric flow rate of the fluid. Accordingly, the behavior of the valve plug body is similar to the operation of a rotameter, which is used to measure volumetric flow rates. The behavior of rotameters is described in the art. Since the travel of the valve plug body within the conical flow element sleeve depends on properties of the fluid, some embodiments may use interchangeable flow element sleeves or springs that may be tailored to the particular fluids to be delivered. For example, if the user intends to pump a highly viscous fluid or a dense fluid, they may choose one particular flow element sleeve or spring, whereas they may select a different flow element sleeve or spring for a less viscous or less dense fluid.

The inventor has realized that the travel of the valve plug body within a conical flow element sleeve can be used to monitor the amount of fluid delivered with each compression/delivery stroke of the pump. Embodiments of the flow meter check valves described herein operate on the principle of using a transducer to sense/measure such travel of a valve plug body/float within the check valve and relate that measurement to the volume delivered. In the illustrated embodiment, the transducer comprises generating coil 307, the sense coil 309, and the magnetic marker 324. Current through the generating coil is used to generate an electromagnetic field (EMF) within the annulus 311 of the stem guide assembly 310 as shown in the illustration. As the magnetic marker 324 is pushed through the EMF by the motion of the float, it influences the EMF so that the EMF changes (i.e., warps or deflects). The time-varying change in the EMF induces a current in the sense coil 309. The magnitude of the current depends on the motion of the magnetic marker within the stem guide assembly and can thereby be used to determine the distance the stem of the float moves within the stem guide, which in turn, is related to the volume of fluid delivered through the check valve. The inventor has determined that this measurement is sensitive to fractions of a millimeter of travel of the float and has a response time on the order of milliseconds.

FIG. 4 illustrates a plot of the displacement of a float of a flow meter check valve as a function of time while the pump is running. The rising edges of the peaks occur during the delivery stroke of the piston. The area under the curve for each peak is correlated to the volume of fluid delivered during a cycle of the pump's piston. Accordingly, once the operation of the flow meter check valve is calibrated to the particular fluid being delivered, as explained further below, the electrical reading from the sense coil 309 can be used to indicate the volume of fluid delivered in each stroke and over time. According to some embodiments, the control circuitry of the control unit may be configured to receive data from the transducer and calculate the volume of fluid delivered with each stroke and/or the volume delivered over time. For example, the control circuitry may be configured to determine the displacement of the float as a function of time (e.g., as shown in FIG. 4) and to integrate the displacement as a function of time to determine the volumetric flow rate. The control circuitry and volume algorithms may include various averaging techniques, e.g., box car averaging, etc.

Also, the electrical signal may be used to detect a fault or problem with the pump. For example, at the point 402 in FIG. 4 the float does not completely return to its rest position in the plug seat. This may indicate that debris has prevented the valve plug body from completely sealing the output valve. According to some embodiments, the system may be configured to issue alert if such event occurs. For example, if the deviation of the return of the signal to the baseline exceeds a predefined threshold, then an alert may be issued.

It should be noted that other transducers for measuring the displacement of the float, stem, and/or valve plug body during the cycling of the pump are within the scope of the disclosure. For example, a portion of the float may comprise a magnetic material and a Hall effect sensor may be used to detect its position. Alternatively, a linear variable differential transformer (LVDT)-type sensor may be used to detect the position of the float's stem within the stem guide. Other embodiments may use an optical sensor, such as a time-of-flight sensor, or the like.

As mentioned above, the data from the flow meter check valve (e.g., the area under the curve shown in FIG. 4) may be calibrated to provide a direct measurement of the fluid delivered by the pump. This calibration may be needed to account for the fluid properties (i.e., viscosity) of the particular fluid, as well as the particular operating conditions of the system. FIG. 5 illustrates an embodiment of a protocol 500 for calibrating flow meter check valve. This protocol may be executed using the control unit 128 (FIG. 1), for example. For example, the control unit may be configured with a calibration mode and may be configured to provide instructions to a user for performing the calibration and for entering appropriate information. According to some embodiments, the calibration protocol may be performed by the control unit without user intervention. According to some embodiments, calibration protocol may be performed remotely, via the telemetry link with a remote location.

The calibration protocol is described here and in FIG. 5 with respect to the system 100 illustrated in FIG. 1. It will be appreciated, however, that similar calibration procedures may be used with systems that differ from system 100 in various ways. At step 502, the pump is either turned off or is otherwise isolated from upstream components of the system. At step 504, an initial volume of fluid is transferred from the tank 102 to the calibrated column or chamber of a known volume 112. In the system 100, this may be achieved by opening the valve 108. Once a desired volume of fluid is added, the valve 108 is closed to isolate the column from the tank. The initial volume should be noted. According to some embodiments, the volume may be determined using the pressure sensor 116. According to some embodiments, the user may enter the initial volume into the control system. Alternatively, the control system may simply read the initial volume from the pressure measurements. At step 506, pumping is initiated. At step 508, readings from the flow meter check valve are correlated to the volume of fluid pumped from the column 112. During the process the control system receives and processes the measurements from the flow meter check valve. For example, the control system may be configured to compute the area under the displacement curve (see, e.g., FIG. 4). These area measurements may be correlated with the volume/pressure measurements from the pressure sensor 116, for example. The control system may be configured to determine a mathematical calibration curve (e.g., a linear relationship, polynomial relationship, etc.) relating the area measurements and volume measurements from the column, for example. These calibration measurements may be performed for a defined period of time, for a given amount of volume delivered, and/or until a predetermined fit or correlation coefficient is achieved. Once the appropriate stop conditions are reached, the calibration routine may be terminated, and the determined calibration relationship may be stored in memory of the control unit. According to some embodiments, the control unit may switch to a measurement mode for providing real-time measurements of volumetric flow.

In the embodiments described above, aspects of the operation of the flow meter check valve, such as its determination of volumetric flow, calibration, system health monitoring, etc., were described as being partially or wholly performed using the control circuitry/control unit 128 of the system 100 (FIG. 1). However, it should be appreciated that embodiments of the flow meter check valve may be configured with its own control circuitry/programming for executing some or all of these functions, either partially or in total. For example, embodiments of the flow meter check valve may be configured with control circuitry configured to perform the calibration routine(s), and/or analyze the transducer data to determine the volumetric flow. Equipment monitoring circuitry within the flow meter check valve may be configured to monitor the operation of the pump and detect faults, as described above.

Although particular embodiments of the present invention have been shown and described, it should be understood that the above discussion is not intended to limit the present invention to these embodiments. It will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention. Thus, the present invention is intended to cover alternatives, modifications, and equivalents that may fall within the spirit and scope of the present invention as defined by the claims.