The present disclosure relates generally to injecting process fluids into a process and, more specifically to injecting a process fluid such as a slurry into a process stream using a drive fluid.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Pumping of process fluids are used in many industries Process fluids may be pumped with a various types of pumps that are driven by a drive fluid. A slurry is one type of process fluid. Slurries are typically abrasive in nature. Slurry pumps are used in many industries to provide the slurry into the process. Sand injection for hydraulic fracturing (fracking), high pressure coal slurry pipelines, mining, mineral processing, aggregate processing, and power generation all use slurry pumps. All of these industries are extremely cost competitive. A slurry pump must be reliable and durable to reduce the amount of down time for the various processes.
Slurry pumps are subject to severe wear because of the abrasive nature of the slurry. Typically, slurry pumps display poor reliability, and therefore must be repaired or replaced often. This increases the overall process costs. It is desirable to reduce the overall process costs and increase the reliability of a slurry pump.
Direct acting liquid driven pumps have been developed, in which a high pressure drive fluid is used to pressurize a process fluid by direct contact, or separated by a membrane or piston. The known system described below is used for a slurry as the process fluid.
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Pressurized fluid from each cylinder 12, 14 is communicated through the slurry or process fluid outlet ports 18, 22 through respective check valves 36, 38. The check valves 36, 38 open when the pressure within the process portions 32, 34 is greater than the check valve set pressure. High pressure process fluid is communicated from the process fluid outlet ports 18, 22 to a high pressure process 40. The high pressure process 40 may be one of the various types of processes described above.
Each cylinder 12, 14 includes a respective piston 50, 52. The piston 50, 52 divides the respective cylinders 12, 14 into a process fluid portion 32, 34 and a drive fluid portion 54, 56.
The cylinder 12 includes a drive fluid inlet port 58 and a drive fluid outlet port 60. The cylinder 14 includes a drive fluid inlet port 62 and a drive fluid outlet port 64. Fluid is communicated from a high pressure drive fluid reservoir 66 through a three-way valve 68 to the drive inlet port 58, which is in fluid communication with the drive portion 54. High pressure drive fluid is also communicated from the three-way valve 68 to the drive fluid inlet port 62, which is in fluid communication with the drive fluid portion 56.
The drive fluid outlet ports 60, 64 are in communication with a three-way valve 70, which selectively communicates low pressure drive fluid to a low pressure reservoir 72.
Cylinder 12 has a first end 74 which corresponds to a process fluid end, and includes a proximity sensor 76. The cylinder 12 has a second end that corresponds to a drive fluid end 78. The drive fluid end 78 has a proximity sensor 80. The process fluid end 74 also includes the process fluid inlet port 16 and the process fluid outlet port 18. The drive fluid end 78 includes the drive fluid inlet port 58 and the drive fluid outlet port 60.
The cylinder 14 includes a first end 82 that corresponds to a process fluid or slurry end and includes a proximity sensor 84. The cylinder 14 includes a second end 86 that corresponds to drive fluid end. The second end 86 includes a proximity sensor 88. The proximity sensors 76, 80, 84 and 88 detect when the respective pistons 50, 52 are at the respective ends of the cylinders 12, 14.
In operation, high pressure fluid from the high pressure fluid reservoir 66 is selectively coupled to either the drive fluid portion 54 or the drive fluid portion 56, but not both. The pistons 50, 52 are preferably 180° out of phase. That is, when the piston 50 is moving left, the piston 52 is moving right, and vice versa. In
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The present disclosure is directed to a method and system that allows abrasive slurries to be injected into a very high pressure process stream with minimal wear. The system provides high reliability due to the reduced amount of wear.
In one aspect of the disclosure, a system includes a first fluid cylinder having a first process fluid end and a first drive fluid end. The first cylinder comprising a first process fluid inlet port and a first process fluid outlet port disposed at the first process fluid end of the first fluid cylinder and first drive fluid inlet port and a first drive fluid outlet port disposed at the first fluid end of the first fluid cylinder. The first fluid cylinder is oriented vertically. A first liquid fluid interface is disposed between the first process fluid end and the first drive fluid end to divide the first fluid cylinder into a first process fluid portion and a first drive fluid portion. A first pump pumps drive fluid to the drive fluid portion to drive the fluid interface to pressurize the process fluid.
In another aspect of the disclosure, a method includes communicating drive fluid into a drive fluid portion of a fluid cylinder having a first end and a second end. The fluid cylinder comprises a process fluid inlet port and a process fluid outlet port disposed at the first end and drive fluid inlet port and a drive fluid outlet port disposed at a second end of the cylinder. The method further includes moving a fluid interface to pressurize process fluid in response to communicating drive fluid to the drive portion, forcing pressurized process fluid from a process fluid outlet port, communicating drive fluid past a valve in the process fluid outlet port, and closing the valve within the drive fluid.
In yet another aspect of the disclosure, a system includes a fluid cylinder having a first end and a second end. The fluid cylinder comprises a process fluid inlet port and a process fluid outlet port disposed at the first end and drive fluid inlet port and a drive fluid outlet port disposed at the second end. A piston is disposed between the first end and the second end to divide the cylinder into a process fluid portion and a drive fluid portion. The piston has a first face within the process fluid portion and a second face within the drive fluid portion. The piston comprises a piston port therethrough. The piston port has a check valve for selectively passing drive fluid from the drive fluid portion therethrough. The first face has a circumferential clearance adjacent to an interior wall of the fluid cylinder. The piston comprises a plurality of channels fluidically coupling the piston port and the circumferential clearance so that drive fluid from the drive fluid portion displaces process fluid from the circumferential clearance.
In a further aspect of the disclosure, a method includes communicating drive fluid into a drive fluid portion of a fluid cylinder having a first end and a second end. The fluid cylinder has a process fluid inlet port and a process fluid outlet port disposed at the first end and drive fluid inlet port and a drive fluid outlet port disposed at a second end of the cylinder. The method further includes moving a piston to pressurize process fluid in response to communicating drive fluid to the drive portion. The piston comprises a piston port therethrough. The method further includes selectively communicating drive fluid from the drive fluid portion though a check valve disposed within the piston port, communicating drive fluid through channels within the piston to a circumferential channel disposed within a process fluid face of the piston and displacing process fluid from the circumferential channel as the piston moves toward the first end.
In another aspect of the disclosure, a method includes communicating drive fluid into a drive fluid portion of a fluid cylinder having a first end and a second end. The fluid cylinder includes a process fluid inlet port and a process fluid outlet port disposed at the first end and drive fluid inlet port and a drive fluid outlet port disposed at a second end of the cylinder. The method also includes moving a piston to pressurize process fluid in response to communicating drive fluid to the drive portion, communicating drive fluid through an axial groove in an interior wall of the fluid cylinder adjacent to the first end, communicating drive fluid through the axial groove when the piston when the piston reaches the axial groove and stopping movement of the piston toward the first end.
In another aspect of the disclosure, a system includes a first fluid cylinder having a first piston dividing the first fluid cylinder into a first process portion and a first drive fluid portion. The first drive fluid portion includes a first drive fluid inlet port and a first drive fluid outlet port. The system further includes a second fluid cylinder having a second piston dividing the second fluid cylinder into a second process portion and a second drive fluid portion. The second drive fluid portion includes a second drive fluid inlet port and a second drive fluid outlet port. A first three way valve is coupled to a high pressure drive fluid source and the first drive fluid inlet port and the second drive fluid inlet port. The first three way valve has a first state coupling the high pressure drive fluid source to the first drive fluid inlet port, a second state coupling the high pressure drive fluid source to the second drive fluid inlet port and a first dead zone state not coupling the high pressure drive fluid source to either the first drive fluid inlet port or the second drive fluid inlet port. The system also includes a second three way valve coupled to a low pressure drive fluid reservoir and the first drive fluid outlet port and the second drive fluid outlet port. The second three way valve has a first state coupling the first drive fluid outlet port to the low pressure drive fluid reservoir, a second state coupling second drive fluid outlet port to the low pressure drive fluid reservoir and a second dead zone state not coupling the low pressure drive fluid reservoir to either the first drive fluid outlet port or the second drive fluid outlet port. A first valve is coupled between the first three way valve and a high pressure drive fluid source. A second valve is coupled between the drive fluid outlet and the second three way valve. A third valve is coupled between the three way valve and second drive fluid inlet port. A fourth valve is coupled between second three way valve and the drive fluid reservoir. A first proximity sensor or a flow meter generates a first proximity signal corresponding to a first proximity of the first piston relative to the first drive fluid inlet port. A second proximity sensor or the flow meter generates a second proximity signal corresponding to a proximity of the second piston relative to the second drive fluid inlet port. A controller is coupled to the first valve, the second valve, the third valve and the fourth valve. The controller switches the first three way valve to the first dead zone state in response to the first proximity signal. The controller gradually opens the first valve or said second valve when the first three way valve is in the first dead zone state and gradually opens the third valve or the fourth valve when the second three way valve is in the second dead zone state.
In another aspect of the disclosure, a method includes operating a three way valve having a first state communicating fluid therethrough, a second state communicating fluid therethrough and third state not communicating fluid therethrough. The method further includes communicating drive fluid to a fluid cylinder through incoming piping in the first state. The method further includes detecting a piston proximity to a drive fluid end of a drive fluid portion of fluid cylinder and generating a proximity signal, and in response to the proximity signal, switching the three way valve to the third state. The method further includes opening a bypass valve to equalize a first pressure in a drive portion of the fluid cylinder to correspond to a second pressure in the incoming piping or outgoing piping. Also after opening the bypass valve, switching the three way valve to the second state is performed.
In another aspect of the disclosure, a system includes a first fluid cylinder having a maximum operating pressure and a second fluid cylinder disposed around the first fluid cylinder forming an annular space therebetween. The second fluid cylinder includes a first end and a second end. A fixed mount is coupled to the second fluid cylinder disposed near the first end. A roller mount is coupled to the second fluid cylinder disposed near the second end. The annular space is at a pressure equal to or greater than the maximum operating pressure.
In another aspect of the disclosure, a method includes communicating drive fluid to an annular space between a first fluid cylinder having a maximum drive fluid operating pressure and a second fluid cylinder disposed around the first fluid cylinder to form the annular space therebetween, communicating drive fluid to the annular space, maintaining about the maximum drive fluid operating pressure within the annular space while moving a piston toward a first end of the first fluid cylinder, fixedly mounting a second end of the second fluid cylinder, roller mounting the first end of the second fluid cylinder to allow the second fluid cylinder to move relative to a roller.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical or. It should be understood that steps within a method may be executed in different order without altering the principles of the present disclosure.
The following description is set forth with respect to a slurry injection system. However, other types of process fluids may be injected into a process using a drive fluid according to the teachings of the disclosure.
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In this example, the low pressure tank 120 and pump 106 and 170 have replaced the high pressure fluid reservoir and the low pressure reservoir 72 of
In the prior system, position sensors were used to sense the location of the pistons and to generate a command to control the three-way valves. The flow meter 122 measures the amount of high pressure drive fluid entering the fluid cylinder 12 from a time when the three-way valve 68 opens. When a preset amount of flow is reached, which may correspond to a volume slightly less than the cylinder, a state change is commanded for both the three-way valves 68 and 70. The flow meter 124 may be used to measure the amount of drive fluid leaving the cylinders 12, 14. If there is a difference between the amount of flow that enters the cylinder and that which leaves the other cylinder, then the piston may not be returning to the expected position. The amount of flow into or out of a cylinder may be adjusted until flow equalization is obtained, based on a measurement of the two flow meters.
A controller 132 may be in electrical communication with the flow meter 122, the valve 102, the pump 106, the three-way valve 68, the valve 108, the valve 112, the valve 116, the three-way valve 70 and the flow meter 124. The controller 132 is also in fluid communication with the proximity sensors 80, 88. The flow meters and the proximity sensors are used to perform the same function, and thus, either the flow meters or the proximity sensors may be used to generate a signal that corresponds to the proximity of the first piston relative to the first drive fluid inlet port and/or the first drive fluid outlet port, and a second proximity of the second piston relative to the second drive fluid inlet port or the second drive fluid outlet port. The controller 132 monitors the movement of the piston by either the proximity signal or by the flow meter signals. When one of the pistons is proximate to the drive fluid end, this indicates to the controller that the three-way valve must be switched so that the piston can move in the opposite direction. In response to the piston being proximate to the drive fluid end of the cylinder, the three-way valves are switched to a dead zone state. For the first piston, either valve 102 or 108 are slowly and controllably opened to equalize the pressure between the drive portion and the associate piping. If the fluid cylinder 14 is proximate the drive end, the three-way valve 70 is placed into a second dead zone state while either valve 112 or 116 are controllably and slowly opened to equalize the pressure between the drive portion and the piping 114 or the piping 118, respectively.
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In step 810, the piston proximity to the drive fluid end of the cylinder is detected. As mentioned above, the proximity of the drive fluid to the end of the cylinder may be determined by a proximity sensor signal, or by determining the flow of fluid into, out of, or both, of each of the drive fluid cylinders. In step 812, a three-way valve is switched to a dead zone state in response to the proximity signal indicating the end of the cylinder has been reached. In step 814, a bypass valve is slowly opened while the three-way valve is in a dead zone state. The bypass valves are illustrated in
In step 818, the state of the three-way valves is changed to a non-dead zone state. That is, fluid is then communicated to or from the three-way valve in step 820.
The system uses two fluid cylinders 12, 14 that operate directly opposite to each other. That is, as one fluid cylinder is filling with drive fluid, the other fluid cylinder is removing drive fluid. In operation, the first fluid cylinder is receiving fluid from the drive fluid source while the second fluid cylinder is removing drive fluid and communicating the drive fluid to the drive fluid reservoir. When the proximity sensor is reached at the first fluid cylinder, both three-way valves are placed in a non-fluid communicating state. Pressure is relieved using the bypass valve. For example, the bypass valve 108 opens and bypass valve 112 opens. By opening bypass valve 108, the drive fluid is equalized to the fluid in the outgoing piping 110, so that when the bypass valve 70 communicates fluid to the fluid reservoir from the first fluid cylinder 12, the pressure is slowly equalized. Likewise, the bypass valve 112 is slowly opened so that the fluid cylinder is exposed to the pressure in the incoming piping 114. After the second fluid cylinder 14 reaches the proximity sensor 88, the opposite takes place. That is, the valves 102 and 116 are opened to expose the respective cylinders to the pressure in the piping 104 and 118.
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A controller 210, such as a programmable logic controller or another type of control unit, may be used to control the actuation of the three-way valves 68, 70. The actuation of the three-way valves 68, 70 may be performed in response to signals from one or more flow meters. Because the pistons have been eliminated, precisely monitoring the position of the pistons within the cylinders as performed above is not required. For example, if the fluid interface moves beyond the cylinder volume, such as into the piping below the check valves, no damage occurs to the system. In this example, an RPM counter 212 may be used to communicate the amount of fluid to the controller 210. This may eliminate the need for the flow meter 122. A second flow meter 214 measures the flow of slurry or process fluid into the cylinders. To maintain equal pumping of drive fluid and slurry, the controller 210 may be programmed to admit equal amounts of drive fluid and process fluid such as slurry. The flow meter 214 is in electrical communication with the controller 210.
The system 10′″ may allow the system to be overpumped with drive fluid as described below. That is, more drive fluid may be pumped than process fluid, to allow the process fluid to be cleaned from the check valves. This will allow the check valves to open and close in relatively pure drive fluid. Because the fluid in the process fluid is diluted by overpumping the drive fluid, pump 24 may continuously circulate process fluid from the tank 26 to minimize the dilution of the slurry. A control valve 216 may regulate the flow of slurry and pressure in the circulation loop. The control valve 216 may also be in communication with the controller 210.
In this example, it is desirable to gradually flow the incoming and outgoing drive fluid and the incoming and outgoing process fluid to avoid interrupting the fluid interfaces 204, 206.
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In step 1612, the high pressure drive fluid is communicated to a second end of the cylinder. In
In step 1614, a fluid interface is formed between the slurry or process fluid and the drive fluid. The fluids may be slowly added to prevent mixing, and to encourage the formation of the fluid interface. As will be described below, smooth inlet surfaces may be used to prevent the inlet flow from mixing.
In step 1616, the fluid interface is forced to move by increasing the amount of drive fluid, and therefore the pressure, in the cylinder. In an overpumping condition, the fluid interface is forced past the outlet check valve at the process fluid end so that when the check valve is closed, the check valve operates within the relatively clean drive fluid.
In step 1618, the outlet valve or check valve is closed when the drive fluid is adjacent to the check valve. That is, the fluid interface is downstream of the check valve. This allows longer operation of the check valves.
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An accumulator 1834 may be incorporated into the system and may be fluidically coupled to the annular space 1818. The accumulator 1834 helps insure proper functioning of the check valve 1820 by allowing some flow into the annular space.
Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.
This application is a non-provisional application of provisional application 62/111,270, filed Feb. 3, 2015 and 62/261,936, filed Dec. 2, 2015, the disclosures of which are incorporated by reference herein.
Number | Date | Country | |
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62111270 | Feb 2015 | US | |
62261936 | Dec 2015 | US |