WO2015112523A1

WO2015112523A1 - Pump system with flow control

Info

Publication number: WO2015112523A1
Application number: PCT/US2015/012124
Authority: WO
Inventors: Benjamin MINTEER; Alex P. BRINKMAN; Don Miles WILBUR; Trevor N. Iund
Original assignee: Caterpillar Inc.
Priority date: 2014-01-24
Filing date: 2015-01-21
Publication date: 2015-07-30
Also published as: US20150211529A1

Abstract

A pump system (10) is provided including a power source (12), a pump (14) and a transmission (15). First and second sensors (28, 30, 32, 34) are configured to respectively provide information indicative of at least one actual first operating condition relating to the pump (14) and to information indicative at least one operating condition relating to the transmission (15). A controller (26) is configured to adjust the power source (12) or the transmission (15) based on an output flow rate of the pump (14). The controller (26) is configured to perform a first comparison of the first operating condition and a predetermined first operating condition and a second comparison of the second operating condition to a predetermined second operating condition and based on the first and second comparisons determine if the controller should continue to adjust the power source (12) or the transmission (15) based on the output flow rate of the pump (14).

Description

Description PUMP SYSTEM WITH FLOW CONTROL

Technical Field

This patent disclosure relates generally to pump systems and, more particularly, to pump systems with flow control.

Background

A slurry pump is a type of pump that increases the pressure of a liquid/solid particulate mixture. Slurry pumps are widely used to transport raw minerals and ore (e.g., coal, sand, oil, etc.), waste material (e.g., sewage), and refined products. One application for such slurry pumps is oil or gas well cementing systems. Part of the process of preparing an oil or natural gas well for further drilling, production or abandonment involves pumping cement into place in a wellbore. Well cementing systems typically use a power source (e.g., an engine or electric motor) connected through a transmission to a fixed displacement pump. The transmission provides a direct mechanical connection from the power source to the pump. In these configurations, the power source is typically operated at a constant speed to provide a single flow rate of cement from the pump for each available gear ratio.

One problem with a conventional slurry pump system involves flow rate consistency. In particular, as a load on the pump changes due to changing conditions at an associated well or mine (e.g., due to a density change or plugged hose), the flow rate of slurry from the pump will likewise fluctuate. Typically, the operator manually adjusts the engine governor and transmission control settings to achieve and maintain the desired pump flow and pressure. Given the variability associated with well cement and the well cementing process, it is very difficult for the operator to manually control cement flow and pressure throughout the entire cementing process.

An attempt to address fluctuations in pump flow rate is described in U.S. Patent No. 6,033,187 that issued to Addie on March 7, 2000 ("the Ί87 patent"). Specifically, the Ί87 patent discloses a way to determine an instantaneous pressure produced by a slurry pump. Using this pressure, along with an overall total pipeline resistance, an optimal operating speed of the pump may then be determined. This speed may then be controlled, for example by changing the output ratio of the gear box (if available), to improve stability of the pumping system.

Although the system of the Ί87 patent may be adequate for some applications, it may also suffer from drawbacks. In particular, it may be difficult and time consuming (or not even possible) to change the output ratio of the gear box. In addition, this change may only provide step-wise adjustment in pump speed, which may lack fine control necessary for some operations. Further, the gear box required to provide the desired ratio(s) may be large, heavy, and expensive.

Summary

In one aspect, the disclosure describes a pump system including a power source, a pump and a transmission configured to operatively connect an output rotation of the power source to an input rotation of the pump. A first sensor is configured to provide information indicative of at least one actual first operating condition relating to the pump. A second sensor is configured to provide information indicative at least one operating condition relating to the transmission. A controller is in communication with the first sensor and the second sensor. The controller is configured to the power source or the transmission based on an output flow rate of the pump. The controller is configured to perform a first comparison of the first operating condition and a predetermined first operating condition and a second comparison of the second operating condition to a predetermined second operating condition and based on the first and second comparison determine if the controller should continue to adjust the power source or the transmission based on the output flow rate of the pump.

In another aspect, the disclosure describes a method of controlling a pump system having a power source, a pump and a transmission configured to operatively connect an output rotation of the power source to an input rotation of the pump. The method includes the step of selectively adjusting the power source or the transmission based on an output flow of the pump. A first parameter indicative of at least one first operating condition relating to the pump is sensed. A second parameter indicative of at least one second operating condition relating to the transmission is sensed. A first comparison of the first actual operating condition and a predetermined first operating condition is performed. A second comparison of the second actual operating condition and a predetermined second operating condition is performed. It is determined based on the first and second comparisons if the power source or transmission should continue to be adjusted based on the output flow of the pump.

In yet another aspect, the disclosure describes a pump system including an engine, a slurry pump, and a transmission configured to operatively connect an output rotation of the power source to an input rotation of the pump. The transmission includes a torque converter fluidly connecting an output of the engine to an input of a gear box. The gear box is mechanically connected to an input of the slurry pump and has a plurality of gear combinations. A first sensor is configured to provide information indicative of at least one first actual operating condition relating to the slurry pump. A second sensor is configured to provide information indicative of at least one actual operating condition relating to the transmission. A controller is in communication with the first sensor and the second sensor. The controller is configured to adjust the engine or the transmission based on an output flow rate of the slurry pump. The controller is configured to perform a first comparison of the first operating condition and a predetermined first operating condition and a second comparison of the second operating condition to a predetermined second operating condition. Based on the first and second comparisons, the controller determines if the controller should continue to adjust the engine or the transmission based on the output flow rate of the slurry pump. Brief Description of the Drawings

FIG. 1 is a schematic side view of an exemplary pump system according to the present disclosure.

FIG. 2 is a schematic diagram of a pump system operatively connected to a well according to the present disclosure.

FIG. 3 is a flow chart illustrating one method of performing a flow control test according to the present disclosure. Detailed Description

This disclosure generally relates to a pump system and associated method that provides a flow control test. With particular reference to FIG. 1, an exemplary pump system 10 is shown. The pump system 10 may include, among other things, a power source, such as an engine 12 operatively connected to a pump 14 by way of a transmission 15, including in this case a torque converter 16 and a gear box 18. The engine 12 may be configured to generate a rotational power output. The torque converter 16 may be configured to transfer at least a portion of the power output to the gear box 18. The gear box 18 may convert the rotation received from the torque converter 16 to a rotation having a different speed and torque, and deliver the converted rotation as an input to drive the pump 14. FIG. 2 is a schematic diagram showing the pump system 10, including the engine 12, transmission 15 and pump 14, operatively connected to a well 19 for pumping a fluid or slurry, such as cement, into the well 19. While aspects of the present disclosure may be described in connection with a well cementing operation, the present disclosure is not limited to that particular application. Rather, the present disclosure can be applied to any application in which a fluid is pumped and is particularly applicable to slurry pumping operations.

The engine 12 may produce a rotational output having both speed and torque components, and may embody an internal combustion engine. For example, the engine 12 may be a diesel engine, a gasoline engine, a gaseous fuel-powered engine, or any other engine apparent to one skilled in the art. The engine 12 may contain an engine block having a plurality of cylinders (not shown), reciprocating pistons disposed within the cylinders (not shown), and a crankshaft operatively connected to the pistons (not shown). The internal combustion engine may use a combustion cycle to convert potential energy (usually in chemical form) within the cylinders to a rotational output of the crankshaft, which may in turn rotate an input of the transmission 15, in this instance the torque converter 16.

The torque converter 16 may be used to transmit power from the crankshaft of the engine 12 to the gear box 18. In one embodiment, the torque converter 16 may be a hydro-mechanical device that allows the crankshaft of the engine 12 to rotate somewhat independently of an input shaft of the gear box 18. In this embodiment, the torque converter 16 includes an impeller (not shown) fixedly connected to the crankshaft of the engine 12, and a turbine (not shown) fixedly connected to the input shaft of the gear box 18. The impeller may be fluidly coupled with the turbine, such that as the impeller rotates, a pressurized flow of fluid may be generated and directed through the turbine, driving the turbine to also rotate. At low fluid flow rates and pressures (or when the pump 14 is heavily and/or suddenly loaded), the impeller may rotate at a higher speed relative to the turbine. However, as the pressure and the flow rate of the fluid conducted between the impeller and the turbine increases (or when the pump 14 is lightly loaded), the rotational speed of the turbine may approach the rotational speed of the impeller. This may allow the engine 12 to rotate at a different speed and torque than the gear box 18, depending on operating conditions, with the difference in speed and torque being accounted for by shearing losses (i.e., heat) within the fluid.

Alternatively, the torque converter 16 could be another type of fluidic or non-fluidic coupling, if desired. For example, the torque converter 16 could include friction plates coupled to the crankshaft and gear box shaft. The friction plates could be configured to slidingly and rotationally engage each other, and thereby transfer a percentage of the power generated by the engine 12 to the gear box 18. Other configurations of the torque converter 16 may also be possible.

In some embodiments, the torque converter 16 may also include a lockup clutch (generically represented by a box 20 in Fig. 1) disposed in parallel with the impeller and turbine (or friction plates, if so equipped). The lockup clutch 20 may be configured to selectively and mechanically lock the crankshaft directly to the gear box input shaft, such that both shafts rotate at the same speed. The lockup clutch 20, if included, may be activated manually or automatically, as will be described below.

The gear box 18 may include numerous components that interact to transmit power received from the engine 12 (via torque converter 16) to the pump 14. In particular, the gear box 18 may embody a mechanical transmission having one or more forward gear ratios. In some embodiments, the gear box 18 may also include a neutral position and/or one or more reverse gear ratios. In embodiments where more than one gear ratio is included, the gear box 18 may additionally include one or more clutches (not shown) for selectively engaging predetermined combinations of gears (not shown) that produce a desired gear ratio.

The gear box 18, if equipped with multiple gear combinations, may be an automatic-type transmission wherein shifting between gear ratios is based on a power source speed, a maximum operator selected gear ratio, a load from the pump 14, and/or a fluid pressure within gear box 18. Alternatively, the gear box 18 may be a manual transmission, wherein the operator manually engages the desired gear combinations. Regardless of the type of transmission 15, the output of the gear box 18 may be connected to rotatably drive an input shaft of the pump 14.

In one embodiment, each ratio of the gear box 18 may be about 7: 1 or less. In particular, the gear box 18 may be configured to produce an output speed that is about the same as or up to seven times less than an input speed received by the gear box 18. This reduction may typically be too small to accommodate slurry pumping applications with high accuracy. That is, transmissions typically used in slurry pumping applications may require speed reductions of 7: 1 or greater. However, when used in conjunction with the torque converter 16 in its unlocked state (i.e., during a torque converter drive mode), slippage between the impeller and the turbine (or between the friction plates) combines with the ratio reduction of the gear box 18 to produce sufficiently high speed reductions (i.e., reductions greater than about 7: 1).

The pump 14 may be a positive displacement plunger type pump capable of generating an output flow rate of about 10-20 gallons per minute. The pump 14 may be configured to transport a fluid/particle mixture (e.g., oil sands, sewage, petroleum, petrochemicals, cement, etc.). The mixture may enter the pump and be accelerated by the plungers (not shown), causing the mixture to flow outward through the housing. In this configuration, the plungers may be directly driven by the output shaft of the gear box 18 at a speed that is about seven or more times slower than the output speed of the power source 12. It is contemplated that the pump 14 may be a different type of pump, if desired, such as a lobe pump, centrifugal pump or a peristaltic hose pump. The pump 14 may produce an output flow rate dependent on conditions of the fluid/particle mixture (e.g., density, viscosity, etc.), size of the plungers and housing, and the input rotation (i.e., speed and torque) provided by the gear box 18. A controller 26 may be associated with pumping system 10, and configured to regulate the output flow rate of the pump 14. In particular, controller 26 may be configured to receive an indication of, and/or calculate an actual output flow rate of the pump 14, receive from the operator an indication of a desired output flow rate of the pump 14, and responsively adjust operation of the engine 12 or the transmission 15 to reduce an error between the actual and desired output flow rates. The controller 26 may be configured to adjust the speed of the engine 12 by adjusting fueling of the engine 12. With respect to the transmission 15, the controller 26 may be configured to adjust the gear of the transmission 15 and/or the state of the lock-up clutch 20 to reduce the error between the actual and desired output flow rates.

The operator of pumping system 10 may be able to input instructions via one or more interface devices located at a control panel that also houses the controller 26. These instructions may include, among other things, a desired output flow rate of the pump 14, a desired gear ratio of the gear box 18, and/or a status of the lockup clutch 20 (e.g., engaged or disengaged). Signals indicative of these instructions may be directed to the controller 26 for further processing.

The controller 26 may further be configured to monitor various operational parameters of the pump system 10. More specifically, the controller 26 may be configured to perform a test on the condition of the pump system 10 by receiving information about one or more actual operational parameters of the pump system 10 and comparing that information to predefined operational parameters. The controller 26 may further be configured to determine from the results of that comparison whether the pump system 10 should continue operating based on flow control.

The actual operational parameters of the pump system 10 that may be used by the controller 26 in performing the test may include information relating to the load on the pump 14 and the conditions in the application in which the pump system 10 is operating, e.g. the well 19 conditions for a well cementing application. The operational parameters relating to the load on the pump 14 and the well 19 condition may include, in one embodiment, the actual flow rate of the pump 14, the system pressure and operating parameters of the transmission 15. In one example, information regarding the actual flow rate of the pump 14 may be communicated to the controller 26 by a sensor 28 associated with the input shaft of the pump 14. In this example, the sensor 28 is a speed sensor and signals generated by the sensor 28 may be used by the controller 26, such as through information provided in the controller 26 on the configuration of the pump 14, to calculate or otherwise determine the actual flow rate of the pump 14. It is contemplated, however, that the sensor 28 could otherwise be configured to directly sense the actual flow rate and/or sense other or additional flow rate parameters (e.g., pressure) that subsequently may be used by the controller 26 to calculate the actual output flow rate, if desired.

Information regarding the system pressure may be provided by a sensor 30, for example, a pressure sensor, arranged and configured to

determining the pressure in the system at a point downstream of the discharge of the pump 14. In one embodiment, the pressure sensor 30 may be arranged directly at the pump 14. Alternatively, the pressure sensor 30 may be arranged somewhere in the discharge line connecting the pump 14 to the particular application load, such as the well 19. If desired, the sensor 30 could otherwise be arranged and configured to sense other or additional system parameters that subsequently may be used by the controller 26 to calculate the actual system pressure.

The information regarding the operating parameters of the transmission 15 that are communicated to the controller 26 may include information about the input and output speeds of the torque converter 16. In the schematic drawing of FIG. 2, information relating to the input speed of the torque converter 16 is provided by a sensor 32 (e.g., a speed sensor) arranged and configured to determine the output speed of the engine 12. While this sensor 32 is shown schematically at the engine 12 in FIG. 2 it should be understood that the sensor 32 could be arranged in other locations including at the torque converter 16. The information regarding the output speed of the torque converter 16 may be provided a sensor 34 arranged and configured to determine the output speed of the torque converter 16. In FIG. 2, this sensor 34 is shown

schematically arranged at the transmission 15. However, it will be appreciated that the sensor 34 may be arranged in other locations. For example, the sensor 34 could be located at the output of the gear box 18 (such as when a torque converter is not provided) or at the input of the pump 14. In particular, information regarding the output speed of the torque converter 16 may be calculated by the controller based on information from the sensor 28 arranged at the input shaft of the pump 14.

Information regarding the load on the pump 14 may be calculated by the controller 26 based on the information monitored regarding the transmission operating parameters including the input speed (e.g., the power source output speed) and output speed of the torque converter 16. In particular, when the lockup clutch 20 is disengaged, the controller 26 may use the information relating to the input speed of the torque converter 16 from sensor 32 (measured as engine speed) and the information about the output speed of the torque converter 16 from sensor 34 to calculate the torque converter 16 output torque using lookup tables or maps relating to the torque converter provided in the controller. The operating parameters of the pump system 10 relating to load on the pump 14 also may be provided or calculated by the controller 26 in other ways. For example, a torque meter may be provided that is arranged and configured to provide information regarding the output torque of the

transmission 15, such as at the output of the torque converter 16 or at the output of the gear box 18.

The operational parameters of the pump system 10 relating to the application in which the pump system 10 is being used, for example the well 19, may include information other than the system flow rate and pressure. For example, the operational parameters may include information relating to the fluid or slurry being pumped. This information could include information relating to the density of the fluid or slurry being pumped. As will be appreciated, other "well" related information also could be monitored and used by the controller 26 in performing the testing used to determine whether to discontinue the flow control. Other operational parameters of the pump system 10 that may be monitored and compared with predetermined values during the testing may include vibration information (gathered, for example, by

accelerometers) and temperature information (gathered, for example, by thermocouples) from the engine 12, transmission 15 or pump 14.

The controller 26 may embody a single processor or multiple processors that include a means for controlling an operation of pumping system 10. Numerous commercially available processors may perform the functions of controller 26. The controller 26 may include or be associated with a memory for storing data such as, for example, an operating condition, design limits, performance characteristics or specifications of pumping system 10, operational instructions, and corresponding fueling parameters. This data may be stored within the memory of controller 26 in the form of one or more lookup tables, as desired. Alternatively or additionally, the controller 26 may perform various calculations using data produced by the various sensors and stored in maps. Various other known circuits may be associated with the controller 26, including power supply circuitry, signal-conditioning circuitry, solenoid driver circuitry, communication circuitry, and other appropriate circuitry. Moreover, as shown in FIG. 2, the controller 26 may be capable of communicating with other components of pumping system 10 such as the engine 12, the transmission 15, the pump 14 and the sensors 28, 30, 32, 34 via either wired or wireless transmission and, as such, controller 26 may be connected to or alternatively disposed in a location remote from power source 12 and/or pump 14.

Referring to FIG. 3 of the drawings, a schematic flow diagram is provided that includes various steps that may be implemented by the controller 26 to provide a test to determine if flow control of the pump system 10 should continue. The test may be automatically directed by the controller 26 periodically or in a continuous cycle while the pump system is operating using flow control. In steps 36, 38 and 40, information is collected relating to one or more operational parameters of the pump system 10 including, for example, the actual pump load, the system flow rate and the transmission 15 operating parameters. This information can be collected by the various sensors provided in the pump system 10 including, for example, sensors 28, 30, 32, 34. Information relating to the operating parameters of the pump system 10 other than or in addition to that shown in FIG. 3 also may be collected such as other information relating to the load on the pump 14, the engine 12 operating condition, the transmission 15 operating condition, the pump 14 operating condition, and the application conditions (e.g., the well 19).

The information relating to the operational parameters of the pump system 10 that is collected in steps 36, 38 and 40 is processed as necessary in step 42. The resultant processed information from step 42 is then used in step 44 to compare the actual operational parameters with predetermined operating parameters. In FIG. 3, the controller 26 compares the actual pump load, flow rate and the transmission operating parameters to predetermined values for the pump load, flow rate and transmission operating parameters. The predetermined operating parameters, like the predetermined operating condition, may be set by specific guidelines, specifications or regulations that are unique to the user of the pumping system, the particular application or a governmental body.

In step 46, the controller 26 may determine if the actual pump system operating parameters are within defined limits of the predetermined parameters from step 44. The criteria for determining whether the pump system 10 passes the test can be based on whether one or more of the actual operating parameters exceed or fail to reach the predetermined operating parameters as determined in step 44. If it is determined that the operating parameters are within the defined limits in step 46, the method may proceed back to step 44 and the test cycle is repeated with updated information on the pump load, flow rate and/or transmission parameters. If it is determined that the pumping system has failed the test in step 46, the method may proceed to step 48 and the controller will exit the flow control routine, i.e. discontinue flow control of the pump system 10. Upon discontinuing flow control, the controller may be configured to direct the pump system into a safe operating mode. Industrial Applicability

The present disclosure is applicable to any type of pump system used in an application to generate a flow of fluid. The disclosed pumping system may be particularly applicable to slurry pumping applications involving relatively dense fluid/particle mixtures. As noted previously, one exemplary application for the pump system 10 is a cementing application. In a cementing application, a relatively dense cement slurry is directed into a well bore by the pump 14 during drilling of the well. This slurry displaces drilling fluids in the bore, and forms a casing for the bore as the drilling progresses. In order for the integrity of the casing to be maintained, the flow rate of the slurry into the well bore must be tightly controlled relative to the drilling process.

To initiate operation of the pump system 10 during the cementing process, the operator may input, via the control panel, a desired output flow rate of the pump 14, a desired ratio of the gear box 18, and a desired state of the lockup clutch 20. While pumping the cement slurry into the well bore, the actual output flow rate of pump 14 may be monitored by way of the sensor 28.

Specifically, signals generated by the sensor 28 may be directed to the controller 26 and, based on the values of these signals, the controller 26 may calculate or otherwise determine the actual output flow rate of pump 14. The controller 26 may then determine an error as a function of the actual and desired output flow rates. For example, controller 26 may determine a difference between these flow rates.

If the supply of cement slurry is too fast, relative to advancement of drilling within the well bore, the excess slurry may interfere with the drilling. Similarly, if the supply of cement slurry is too slow, the drilling may outpace casing formation. Accordingly, the controller 26 may be configured to reference the difference between the actual output flow rate and the desired output flow rate with the lookup table stored in memory to determine if a change in the speed of the engine 12, the transmission gear and/or the state of the lockup clutch is required to properly support the drilling operation. A new fuel setting of the engine 12, transmission gear or lockup clutch state may then be determined that produces the required change in speed, and the controller 26 may issue a command to the engine 12 to operate at the new fuel setting.

The test performed by the controller 26 to determine if the flow control should continue can help protect the pump system 10 from damage by, for example, directing it into a safe operating mode when the controller determines that one or more operational parameters are not within predetermined limits. Circumstances in which the flow control could be discontinued due to failure of the test performed by the controller could include a clogged cement line or a significant increase in the density of the cement being pumped into the well.

It will be appreciated that the foregoing description provides examples of the disclosed system and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.

Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

1. A pump system (10), comprising :

a power source (12);

a pump (14);

a transmission (15) configured to operatively connect an output rotation of the power source to an input rotation of the pump;

a first sensor (28, 30, 32, 34) configured to provide information indicative of at least one actual first operating condition relating to the pump

(14);

a second sensor (28, 30, 32, 34) configured to provide information indicative at least one operating condition relating to the transmission (15); and

a controller (26) in communication with the first sensor (28, 30, 32, 34) and the second sensor (28, 30, 32, 34), the controller (26) being configured to adjust the power source (12) or the transmission (15) based on an output flow rate of the pump (14), the controller (26) being configured to perform a first comparison of the first operating condition and a predetermined first operating condition and a second comparison of the second operating condition to a predetermined second operating condition and based on the first and second comparisons determine if the controller (26) should continue to adjust the power source (12) or the transmission (15) based on the output flow rate of the pump (14).

2. The pump system (10) according to claim 1 wherein the first operating condition comprises a pump flow rate.

3. The pump system (10) according to claim 1 wherein the first operating condition comprises a pump discharge pressure.

4. The pump system (10) according to claim 1 wherein the second operating condition is a transmission output speed.

5. The pump system (10) according to claim 1 wherein the second operating condition is a transmission input speed.

6. The pump system (10) according to claim 1 wherein the transmission (15) includes a torque converter (16) fluidly connecting an output of the power source (12) to an input of a gear box (18), the gear box being mechanically connected to an input of the pump (14) and having a plurality of gear combinations.

7. The pump system (10) according to claim 6 wherein the second operating condition is a torque converter output speed.