Continuous Flow Multi-Piston Pump

The present disclosure relates to pumps, and in particular, to hydraulic piston pumps.

Industry experts agree that a reliable and efficient method of sludge, slurry, and paste transfer is accomplished with positive displacement, dual, reciprocating piston pumps, such as a poppet valve system.

The poppet valve system uses suction and discharge poppets to control the movement of material from the feed area into the delivery pipeline. This is accomplished with two piston pumps. While one piston pump is discharging material into the pipeline, the other piston pump is sucking material from the feed system. Then, the piston pumps switch roles. The piston pump that was discharging material sucks in material, and the piston pump that was filling up takes over the discharge task. This is an extremely reliable, efficient, and cost-effective way of conveying materials. A disadvantage of this positive displacement, dual, reciprocating piston pump system is that the material stops forward movement while the pistons change directions, and a pulsation can occur in the pipeline. While this does not affect the efficiency of the unit, it can cause noise and unwanted pipeline movement.

A multi-piston pump includes a first pump configured to execute a discharge stroke, a suction stroke, a compression stroke, a hold, and a changeover, a second pump independent from the first pump, the second pump being configured to execute a discharge stroke, a suction stroke, a compression stroke, a hold, and the changeover; and a controller that coordinates operation of the first pump and the second pump so that while the first pump is executing the discharge stroke, the second pump is executing the suction stroke, the compression stroke, and the hold, and the first pump and the second pump execute the changeover simultaneously and while the second pump is executing the discharge stroke, the first pump is executing the suction stroke, the compression stroke, and the hold and the first pump and the second pump execute the changeover simultaneously.

A continuous flow multi-piston pump includes a pair of sequenced and reciprocating hydraulic pumps, driving material rams within material cylinders. The material cylinders intake and exhaust the desired pumping material that produces a continuous volumetric output, including during the changeover between the pumps. Each pump direction and speed is controlled using independent hydraulic direction, pressure and flow controls to maintain material cylinder output through a common pump discharge housing. Each material cylinder has an associated intake control valve (or suction poppet valve) and or associated exhaust control valve (or discharge poppet valve).

In one example, the operational sequence begins with each cylinder retracting to a known calibrated position or initial state. While retracting, the delivery cylinders intake material through open intake control valves, also known as suction poppet valves. The exhaust control valves, also known as discharge poppet valves, remain closed. The first and second delivery cylinders are performing an intake (or suction) stroke. When the delivery cylinder has reached the desired intake position, the intake stroke is complete, and the system waits for the other delivery cylinder to reach the desired intake position.

Once both cylinders have reached the desired intake position, the first delivery cylinder will extend at a desired speed and allowable pressure, known as the pressure stroke, to exhaust material out of the delivery cylinder and into the pump discharge housing. During a pressure stroke, the associated first suction poppet valve is closed and first discharge poppet valve is opened. During the first delivery cylinder pressure stroke, the pressure required to move the first ram is sampled.

While the first delivery cylinder is performing the pressure stroke, the second delivery cylinder applies hydraulic pressure to extend the second ram, at a static compression speed and at an allowable pressure that is about (just below) equal to the sampled pressure from first delivery piston. During the compression stroke, the suction poppet valve and the discharge poppet valve of the second delivery cylinder remain closed. This operation pressurizes the second delivery cylinder to a pressure that is approximately (just below) equal to the first delivery cylinder. Once that pressure is reached in the second delivery cylinder, the second delivery cylinder holds until the first delivery cylinder reaches the changeover position threshold.

When the first delivery cylinder reaches the changeover position threshold, both cylinders are in changeover, and executing the changeover between the first pump and the second pump simultaneously. During changeover, the discharge poppet valve opens for the second delivery cylinder that has completed a compression stroke and was holding, and the first and second delivery cylinders are now both open to the pump discharge housing. As such, the first pump and the second pump are both executing a discharge stroke during the changeover. The second delivery cylinder allowable pressure is raised to the operating system pressure. At an equal pump speed step and time interval step, the first ram speed ramps down and the second ram speed ramps up. As the rate of material flow decreases from the first delivery cylinder, the rate of material flow increases from the second delivery cylinder. When the speed change is complete for both the first material cylinder and the second material cylinder, or if the first material cylinder reaches an end of travel threshold, changeover is complete. The second material cylinder is now performing its pressure stroke at a desired pump speed and allowable pressure. During the second delivery cylinder pressure stroke, the pressure required to move the second ram is sampled.

When changeover is complete, the first delivery cylinder's hydraulic piston side is vented to a hydraulic tank which allows cylinder drift as the discharge poppet valve closes. The discharge poppet valve for the first delivery cylinder is closed. When the first discharge poppet valve for the first delivery cylinder is closed, the first suction poppet valve for the first delivery cylinder is opened. Hydraulic pressure is applied to the rod side of the first drive piston to retract the first delivery cylinder at a rate that is faster than the rate of the pressure stroke of the second delivery cylinder. The first delivery cylinder is now performing an intake, or suction, stroke. The suction stroke will continue until the calibrated retract position or initial state is achieved.

Once the first delivery cylinder suction stroke is complete, the first delivery cylinder suction poppet valve is closed. Hydraulic pressure is then applied to extend the ram of the first delivery cylinder, at a static compression speed, and at an allowable pressure that is about (just below) equal to the sampled pressure from the second delivery cylinder. During the compression stroke, the suction poppet valve and discharge poppet valve of the first delivery cylinder remain closed. This operation pressurizes the first delivery cylinder to a pressure that is approximately (just below) equal to the second delivery cylinder. Once that pressure is reached in the first delivery cylinder, the first delivery cylinder holds until the second delivery cylinder reaches the changeover position threshold.

When the second delivery cylinder reaches the changeover position threshold, both delivery cylinders are in changeover, executing the changeover between the first pump and the second pump simultaneously. During changeover, the discharge poppet valve opens for the first delivery cylinder that has completed a compression stroke and was holding, and the delivery cylinders are now both open to the pump discharge housing. As such, the first pump and the second pump are both executing a discharge stroke during the changeover. The first delivery cylinder allowable pressure is raised to the operating system pressure. At an equal pump speed step and time interval step, the second delivery cylinder speed ramps down and the first delivery cylinder speed ramps up. As the rate of material flow decreases from the second delivery cylinder, the rate of material flow increases from the first material cylinder. When the speed ramp is complete for both the first delivery cylinder and the second delivery cylinder, or if the second delivery cylinder reaches an end of travel threshold, the changeover is complete. The first delivery cylinder is now performing its pressure stroke at a desired pump speed and allowable pressure.

When the changeover is complete, the hydraulic piston side of the second delivery cylinder is vented to a hydraulic tank which allows cylinder drift as the discharge poppet valve closes. The discharge poppet valve for the second delivery cylinder is closed. When the second delivery cylinder discharge poppet valve is closed, the suction poppet valve for the second delivery cylinder is opened. Hydraulic pressure is applied to the rod side of the second drive piston to retract the second delivery cylinder. The second delivery cylinder is now performing a suction stroke. The suction stroke will continue until the calibrated retract position or initial state is achieved. From here the operational sequence for the continuous flow reciprocating twin multi-piston pump repeats.

is a perspective side view of multi-piston pump.is a perspective end view of multi-piston pump.is a schematic block diagram of multi-piston pump.will be discussed together.

Multi-piston pumpincludes first pump PMPand second pump PMP(shown in), frame, discharge pipe, poppet block, feeder, water box, hydraulic power unit (HPU), drive cylinder (DRC) control modules, first linear position sensor L, second linear position sensor L, and accumulator circuit, which includes single accumulator bottleand double accumulator bottle, controller, and user interface.

First pump PMPincludes first drive cylinder DRC(shown in), first delivery cylinder DC(shown in), first discharge poppet valve DPV, first suction poppet valve SPV, and first linear position sensor L(shown in).

Second pump PMPincludes second drive cylinder DRC, second delivery cylinder DC, second discharge poppet valve DPV, second suction poppet valve SPV, and second linear position L(shown in)

Framesupports first drive cylinder DRC, second drive cylinder DRC, first delivery cylinder DC(shown in), and second delivery cylinder DC. First drive cylinder DRCis parallel to second drive cylinder DRC. First delivery cylinder DCis parallel to second delivery cylinder DC. First drive cylinder DRCis connected to first delivery cylinder DC, and second drive cylinder DRCis connected to second delivery cylinder DC. First drive cylinder DRCand second drive cylinder DRCdrive first delivery cylinder DCand second delivery cylinder DC, respectively. First delivery cylinder DCis fluidly connected to first discharge poppet valve DPVand first suction poppet valve SPV. Second delivery cylinder DCis fluidly connected to second discharge poppet valve DPVand second suction poppet valve SPV.

First discharge poppet valve DPVand second discharge poppet valve DPVare in fluid communication with discharge pipe. First suction poppet valve SPVand second suction poppet valve SPVare fluidly connected to poppet block. Poppet blockcontrols first suction poppet valve SPV, first discharge poppet valve DPV, second suction poppet valve SPV, and second discharge poppet valve DPV. Feederis fluidly connected to first suction poppet valve SPVand second suction poppet valve SPV. Feederprovides material to multi-piston pump. Water boxis positioned between first drive cylinder DRCand first delivery cylinder DCand is also positioned between second drive cylinder DRCand second delivery cylinder DC. Hydraulic power unit (HPU)is supported by frameand connected to first drive cylinder DRCby piston line Pand tank line Tand connected to second drive cylinder DRCby piston line Pand tank line T. DRC control modulesare mounted on frameand are connected to HPU. First linear position sensor Lsenses the position of first drive piston DRPand is electrically connected to controller. First linear position sensor Lsends position information of first pump PMPto controller. Second linear position sensor Lsenses the position of second drive piston DRPand is electrically connected to controller. Second linear position sensor Lsends position information of second pump PMPto controller. Accumulator circuitis mounted on frameand includes single accumulator bottleand double accumulator bottle. Single accumulator bottleis mounted on frameand contains a bladder that stores hydraulic fluid. Double accumulator bottleis mounted on frameand comprises two bottles, each bottle containing a bladder that stores hydraulic fluid. Controlleris also electrically connected to user interface.

First pump PMPincludes first drive cylinder DRC, first delivery cylinder DC, first discharge poppet valve DPV, first suction poppet valve SPV, first linear position sensor L, first drive piston DRP, first ram R, first connecting rod CR, first piston to tank orifice PTO, first pressure sensor PS, first temperature sensor TS, first hydraulic speed/flow HS/F, first hydraulic pressure HP.

Poppet blockincludes first suction poppet control solenoid SPCS, first discharge poppet control solenoid DPCS, first suction poppet rod fluid line SPRFL, first suction poppet piston fluid line SPPFL, first discharge poppet rod fluid line DPRFL, and first discharge poppet piston fluid line DPPFL.

DRC control modulesinclude first piston side tank PST, first rod side tank RST, first piston side pressure PSP, first rod side pressure RSP, first piston side tank fluid lines PSFL, first rod side tank fluid lines RSFL, first piston side pressure fluid lines PSFL, and first rod side pressure fluid lines RSFL.

Second pump PMPincludes second drive cylinder DRC, second delivery cylinder DC, second discharge poppet valve DPV, second suction poppet valve SPV, second linear position sensor L, second drive piston DRP, second ram R, second connecting rod CR, second piston to tank orifice PTO, second pressure sensor PS, second temperature sensor TS, second hydraulic speed/flow HS/F, and second hydraulic pressure HP.

Poppet blockalso includes second suction poppet control solenoid SPCS, second discharge poppet control solenoid DPCS, second suction poppet rod fluid line SPRFL, second suction poppet piston fluid line SPPFL, second discharge poppet rod fluid line DPRFL, and second discharge poppet piston fluid line DPPFL.

DRC control modulesalso include second piston side tank PST, second rod side tank RST, second piston side pressure PSP, second rod side pressure RSP, first piston side fluid line PSFL, first rod side tank fluid line RSFL, second piston side tank fluid line PSFL, second rod side tank fluid line RSFL, second piston side pressure fluid line PSFL, and second rod side pressure fluid line RSFL.

First drive piston DRPmoves within first drive cylinder DRC, and first ram Rmoves within first delivery cylinder DC. First connecting rod CRextends from first drive piston DRPwithin first drive cylinder DRCto first ram Rwithin first delivery cylinder DC, so that movement of first drive piston DRPproduces corresponding movement of first ram Rin first delivery cylinder DC.

Second drive piston DRPmoves within second drive cylinder DRC, and second ram Rmoves within second delivery cylinder DC. Second connecting rod CRextends from second drive piston DRPwithin second drive cylinder DRCto second ram Rwithin second delivery cylinder DC, so that movement of second drive piston DRPproduces corresponding movement of second ram Rin second delivery cylinder DC.

First drive cylinder DRCis connected to first delivery cylinder DC, and second drive cylinder DRCis connected to second delivery cylinder DC. First delivery cylinder DCis fluidly connected to first discharge poppet valve DPVand first suction poppet valve SPVopposite from first drive cylinder DRC. Second delivery cylinder DCis fluidly connected to second discharge poppet valve DPVand second suction poppet valve SPVopposite from second drive cylinder DRC. First suction poppet valve SPV, first discharge poppet valve DPV, second suction poppet valve SPV, and second discharge poppet valve DPVare fluidly connected to poppet block.

Each of first suction poppet valve SPV, first discharge poppet valve DPV, second suction poppet valve SPV, and second discharge poppet valve DPVinclude a rod having a piston within a cylinder on one end and a trapezoidal valve stopper on the other end. Poppet blockcontrols first suction poppet valve SPV, first discharge poppet valve DPV, second suction poppet valve SPV, and second discharge poppet valve DPV.

Hydraulic power unitis connected to first drive cylinder DRCand second drive cylinder DRCvia DRC control modules. First linear position sensor Lsenses the position of the first drive piston DRPin first drive cylinder DRCand provides a first piston position signal to controller. Similarly, second linear position sensor Lsenses the position of the second drive piston DRPin second drive cylinder DRCand provides a second piston position signal to controller. Accumulator circuitsupplies hydraulic fluid to poppet block.

Controlleris electrically connected to poppet block, DRC control modules, and hydraulic power unit. First piston to tank orifice PTOand second piston to tank orifice PTOare fluidly connected to DRC control modules. First pressure sensor PSand first temperature sensor TSsense pressure and temperature information of first pump PMPand provide pressure and temperature signals to controllerfrom first drive cylinder DRC. Second pressure sensor PSand second temperature sensor TSsense pressure and temperature information of second pump PMPand provide pressure and temperature signals to controllerfrom second drive cylinder DRC. First hydraulic pressure HPand second hydraulic pressure HPprovide control signals to controllerfrom hydraulic power unit.

Poppet blockhas first suction poppet control solenoid SPCS, second suction poppet control solenoid SPCS, first discharge poppet control solenoid DPCS, second discharge poppet control solenoid DPCS.

First suction poppet control solenoid SPCSis connected to first suction poppet valve SPVvia first suction poppet rod fluid line SPRFLand first suction poppet piston fluid line SPPFL. First suction poppet rod fluid line SPRFLis a fluid line connected to and between first suction poppet control solenoid SPCSand the rod side of first suction poppet valve SPV. First suction poppet piston fluid line SPPFLis a fluid line connected to and between first suction poppet control solenoid SPCSand the piston side of first suction poppet valve SPV.

Second suction poppet control solenoid SPCSis connected to second suction poppet valve SPVvia second suction poppet rod fluid line SPRFLand second suction poppet piston fluid line SPPFL. Second suction poppet rod fluid line SPRFLis a fluid line connected to and between second suction poppet control solenoid SPCSand the rod side of second suction poppet valve SPV. Second suction poppet piston fluid line SPPFLis a fluid line connected to and between second suction poppet control solenoid SPCSand the piston side of second suction poppet valve SPV.

First discharge poppet control solenoid DPCSis connected to first discharge poppet valve DPVvia first discharge poppet rod fluid line DPRFLand first discharge poppet piston fluid line DPPFL. First discharge poppet rod fluid line DPRFLis a fluid line connected to and between first discharge poppet control solenoid DPCSand the rod side of first discharge poppet valve DPV. First discharge poppet piston fluid line DPPFLis a fluid line connected to and between first discharge poppet control solenoid DPCSand the piston side of first discharge poppet valve DPV.

Second discharge poppet control solenoid DPCSis connected to second discharge poppet valve DPVvia second discharge poppet rod fluid line DPRFLand second discharge poppet piston fluid line DPPFL. Second discharge poppet rod fluid line DPRFLis a fluid line connected to and between second discharge poppet control solenoid DPCSand the rod side of second discharge poppet valve DPV. Second discharge poppet piston fluid line DPPFLis a fluid line connected to and between second discharge poppet control solenoid DPCSand the piston side of second discharge poppet valve DPV.

DRC control modulesinclude first piston side tank PST, first rod side tank RST, first piston side pressure PSP, first rod side pressure RSP, second piston side tank PST, second rod side tank RST, second piston side pressure PSP, second rod side pressure RSP, all of which are modules fluidly connected to hydraulic power unit.

First piston side tank PST, first rod side tank RST, first piston side pressure PSP, and first rod side pressure RSPare also fluidly connected to first drive cylinder DCR. First piston side tank fluid line PSFLis a fluid line connected to and between first piston side tank PSTand the piston side of first drive cylinder DRC. First rod side tank fluid line RSFLis a fluid line connected to and between first rod side tank RSTand the rod side of first drive cylinder DRC. First piston side pressure fluid line PSFLis a fluid line connected to and between first piston side pressure PSPand the piston side of first drive cylinder DRC. First rod side pressure fluid line RSFLis a fluid line connected to and between first rod side pressure RSPand the rod side of first drive cylinder DRC. First piston to tank orifice PTOis fluidly connected to first piston side pressure PSP. First linear position sensor Ldetermines the position of first drive cylinder DRCand first delivery cylinder DC.

Second piston side tank PST, second rod side tank RST, second piston side pressure PSP, and second rod side pressure RSPare fluidly connected to second drive cylinder DCR. Second piston side tank fluid line PSFLis a fluid line connected to and between second piston side tank PSTand the piston side of second drive cylinder DRC. Second rod side tank fluid line RSFLis a fluid line connected to and between second rod side tank RSTand the rod side of second drive cylinder DRC. Second piston side pressure fluid line PSFLis a fluid line connected to and between second piston side pressure PSPand the piston side of second drive cylinder DRC. Second rod side pressure fluid line RSFLis a fluid line connected to and between second rod side pressure RSPand the rod side of second drive cylinder DRC. Second piston to tank orifice PTOis fluidly connected to second piston side pressure PSP. Second linear position sensor Ldetermines the position of second drive cylinder DRCand second delivery cylinder DC.

First drive cylinder DRCdrives first delivery cylinder DC. Second drive cylinder DRCdrives second delivery cylinder DC. First discharge poppet valve DPVopens and closes to discharge material from first delivery cylinder DRC. First suction poppet valve SPVopens and closes to input material to first delivery cylinder DC. Second discharge poppet valve DPVopens and closes to discharge material from second delivery cylinder DC. Second suction poppet valve SPVopens and closes to input material to second delivery cylinder DC.

First discharge poppet valve DPVand second discharge poppet valve DPVare in fluid communication with discharge pipesuch that material is discharged from first delivery cylinder DCand second delivery cylinder DCthrough discharge pipe.

Poppet blockhydraulically controls first suction poppet valve SPV, first discharge poppet valve DPV, second suction poppet valve SPV, and second discharge poppet valve DPVusing hydraulic fluid from accumulator circuit. Accumulator circuitsupplies hydraulic fluid to extend or retract first discharge poppet valve DPV, first suction poppet valve SPV, second discharge poppet valve DPV, and second suction poppet valve SPVbased on signals from first suction poppet control solenoid SPCS, second suction poppet control solenoid SPCS, first discharge poppet control solenoid DPCS, and second discharge poppet control solenoid DPCSof poppet block.

Hydraulic power unit (HPU)is controlled by controllerbased upon inputs from user interfaceand sensor inputs from linear position sensors Land L, pressure sensors PSand PS, and temperature sensors TSand TS. HPUcontrols flow of hydraulic control fluid through DRC control modulesto control the direction and speed of movement of drive pistons DRPand DRPand rams Rand R. In addition, controllercontrols operation of poppet suction valves SPVand SPV, and discharge valves DPVand DPVthrough poppet block.

First suction poppet valve SPVand first discharge poppet valve DPVopen and close based on input from first suction poppet control solenoid SPCSand first discharge poppet control solenoid DPCS. When first suction poppet control solenoid SPCSis activated by controller, hydraulic fluid from accumulator circuitis delivered to first suction poppet valve SPV. When first discharge poppet control solenoid DPCSis activated by controller, hydraulic fluid from accumulator circuitis delivered to first discharge poppet valve DPV. When first suction poppet control solenoid SPCSis not activated, hydraulic fluid from accumulator circuitis not delivered to first suction poppet valve SPV. When first discharge poppet control solenoid DPCSis not activated, hydraulic fluid from accumulator circuitis not delivered to first discharge poppet valve DPV.

Second suction poppet valve SPVand second discharge poppet valve DPVopen and close based on input from second suction poppet control solenoid SPCSand second discharge poppet control solenoid DPCS. When second suction poppet control solenoid SPCSis activated by controller, hydraulic fluid from accumulator circuitis delivered to second suction poppet valve SPV. When second discharge poppet control solenoid DPCSis activated by controller, hydraulic fluid from accumulator circuitis delivered to second discharge poppet valve DPV. When second suction poppet control solenoid SPCSis not activated, hydraulic fluid from accumulator circuitis not delivered to second suction poppet valve SPV. When second discharge poppet control solenoid DPCSis not activated, hydraulic fluid from accumulator circuitis not delivered to second discharge poppet valve DPV.

First piston side tank PSTand first rod side pressure RSPare activated or inactivated by controllerat the same time, while first rod side tank RSTand first piston side pressure PSPare activated or inactivated by controllerat the same time and opposite from first piston side tank PSTand first rod side pressure RSP. Second piston side tank PSTand second rod side pressure RSPare activated or inactivated by controllerat the same time, while second rod side tank RSTand second piston side pressure PSPare activated or inactivated by controllerat the same time and opposite from second piston side tank PSTand second rod side pressure RSP. Controllercoordinates activation of poppet blockwith hydraulic power unitand DRC control modulessuch that first delivery cylinder DCand second delivery cylinder DCmove in conjunction with first suction poppet valve SPV, first discharge poppet valve DPV, second suction poppet valve SPV, and second discharge poppet valve DPVto result in suction or discharge by first delivery cylinder DCand second delivery cylinder DC, respectively, to result in continuous flow through discharge pipe.

For example, controllermay send signals to HPUand accumulator circuitfor second delivery cylinder DCto execute a suction stroke based on linear position information from first linear position sensor Land second linear position sensor L. HPUactivates second rod side pressure RSPand second piston side tank PSTvia hydraulic control fluid. As such, HPUalso uses hydraulic control fluid to activate first piston side pressure PSPand first rod side tank RST. Second drive piston DRPin drive cylinder DRCmoves in response to the hydraulic fluid and delivery cylinder DCexecutes a suction stroke. At the same time, controller signals to poppet blockto activate second suction poppet control solenoid SPCSso that hydraulic fluid from accumulator circuitmoves to second suction poppet valve SPV. As a result, hydraulic fluid moves into the rod side of the cylinder of second suction poppet valve SPV, causing the rod to move such that the valve stopper moves. Second suction poppet valve opens and material enters second delivery cylinder DC.

First delivery cylinder DCand second delivery cylinder DCoperate independently from each other so that the flow from discharge pipeis continuous and near constant. As a result, there is no pulsation in the flow from discharge pipe.

are a flowchart of continuous flow processshowing steps-. Continuous flow processbegins with initiation of startup operation at stepin.

At step, continuous flow system values are initialized by controller. Stepis the first step in the start-up cycle of multi-piston pump, which initiates the continuous flow pump logic at controller.