US3816029A - Pumping unit for constant pulseless flow - Google Patents

Abstract

A pumping unit for high pressure operation of the order of 10,000 psi or greater including upwards of 150,000 to 200,000 psi is disclosed which is essentially pulseless in its discharge, has no packing but utilizes plungers with hydrostatic supports and seals, and for this purpose two pumps and/or intensifiers are employed actuated by a cam directly or through fluid actuators for each cylinder. The cam has a constant rate of rise with a faster return rate. The return position is adjustable by a variably positioned stop or pick-off so that one cylinder will overcome compressibility and commence discharging fluid when the other cylinder finishes thereby providing a steady discharge flow rate. A simple low pressure hydraulic circuit and an air actuating circuit are described.

Description

United States Patent 1191 1111 3,816,029 Bowen et al. 1 1' June 11, 1974 [5 PUMPING UNIT FOR CONSTANT 3,181,571 5/1965 Scheffel 417/521 x PULSELESS FLOW 3,354,792 11/1967 Fuchs 92/174 3,612,727 10/1971 Drake 417/388 [75] Inventors; John C. Bowen, Huntington Valley; 3,704,080 11/1972 Cross 417/486 Rush B. Gunther, Abington, both of Primary ExaminerCarlton R. Croyle [73] Assignee; The Durimn Company, Inc. Assistant Examiner-R chard E. Gluck Dayton Ohio Attorney, Agent, or Fzrm-Zachary T. Wobensmnh, 22 Filed: on. 3, 1972 2nd [21] Appl. No.: 294,637 [57] ABSTRACT A pumping unit for high pressure operation of the [52] US. Cl 4 /2 17/339, 4l /5 order of 10,000 psi or greater including upwards of 417/53 2/865, 4l7/569 150,000 to 200,000 psi is disclosed which is essentially f F041) 9/F04b 17/00,F0 13 21/02 pulseless in its discharge, has no packing but utilizes 1 Field 01 Search plungers with hydrostatic supports and seals, and for 417/536, 319, 223, 539; 92/138, 3 this purpose two pumps and/or intensifiers are employed actuated by a cam directly or through fluid ac- [56] Re enc Clted tuators for each cylinder. The cam has a constant rate UNITED STATES PATENTS of rise with a faster return rate. The return position is 2,010,377 8/1935 Sassen 417/539 X adjustable a variakbly Positioned P f f' so 2,471,117 5/1949 Orshansky. 91/481 x that one Cylmder W111 Overcome compresslblllty and 2,546,034 3/1951 Lansing 417/223 X commence discharging fluid when the other cylinder 2,770,984 11/1956 Loecy 1 92/ 13.5 finishes thereby providing a steady discharge flow 2,771,845 11/1956 Eagan 417/458 X rate. A simple low pressure hydraulic circuit and an Soccal't air actuating circuit are described 2,980,024 4/1961 Pope 92/138 X 3,003,428 /1961 Christenson 417/536 13 Claims, 12 Drawing Figures 52 ya/ 4.9 2.9- )4740,4Z 34 33 33 47 4.9

1 1 I 1 26, 1 28 L 1 1 v11: I vcn V'c luuyj-zitu l:p VT 48 4a PATENTEDJUN 11 I974 Q SHEET 30? 5 PATENTEBJUII 1 1 I914 33% ska-2s saw u or s PUMPING UNIT FOR CONSTANT PULSELESS FLOW BACKGROUND OF THE INVENTION pumps to vary the stroke of the pump for volume or other control. Typical structures for this purpose are shown in U.S. Pats. to Denny, No. 2,612,839; Wolf, No. 212,777; Louis, No. 1,649,356; Eagen No. 2,771,845; Sato et al., No. 3,398,691; Dodson et al., No. 3,301,197; Sheen et al., No. 2,613,606; and Thurman, No. 2,863,471.

Saalfrank, in U.S. Pat. No. 2,620,734, undertakes to obtain constant volume fluid delivery but has very complex structure for this purpose.

It has also been proposed to use various packing ma terials in high pressure pumps but none of these has proven satisfactory for continuous operation say for 8,000 hours at nominal speeds of -30 cycles per minute and pressure levels above 10,000 psi.

In such pumps, if some leakage is permitted in order to reduce the friction between the packing and the plunger, erosion due to the fluid occurs with undesired increase in leakage. The action is accentuated if the leaking liquid is water because of its solvent action. Increase of pressure of water, also, does not bring about an increase in viscosity which is sufficient to decrease leakage.

If the packing is tight enough to prevent leakage then the friction between the packing and the plunger becomes so high that small particles of the packing material are torn off. Alternately, material is transferred to the plunger which then rips off larger portions of packing material. In addition to shortened packing life, particles of packing also cause check valve malfunction.

It has been recognized that hydrocarbon oils and certain other fluent materials become more viscous as the pressure is increased, (see Fuchs, U.S. Pat. No. 3,354,792), and this property is utilized in the apparatus of the present invention for centering the pump piston and prevention of process leakage with lubrication while maintaining steady or pulseless liquid delivery.

Other intensifiers have been proposed in U.S. Pats. to Douglas et al., No. 3,234,882 and Newhall No. 2,189,835, but these have various shortcomings as indicated above and are complex in construction.

SUMMARY OF THE INVENTION In accordance with the invention an intensifier pumping unit is provided in which a pulseless flow is obtained, a cam of special configuration being employed and structure associated with the cam gives an adjustable return stroke of the cam follower, the cam directly or through fluid systems with valves controlling the position of the pump pistons, the pistons preferably having a fluid seal utilizing a fluid whose viscosity increases substantially with increase of pressure.

It is the principal object of the invention of provide a pumping unit which has improved operating characteristics including smooth essentially pulseless delivery of a fluid at very high pressure and with freedom from interruption over extended periods of time of the order of 8,000 hours continuous duty at nominal speeds of 20-30 cycles per minute.

It is a further object of the invention to. provide a pumping unit which is relatively simple in construction and reliable in its action and eliminates the necessity for accumulators or for multi-stage and multiple cylinder pumps with complex valving with careful phasing.

It is a further object of the invention to provide an intensifier pumping unit which includes a variable volume pump having a continuous discharge and which can operate at slow speed as well as at high speeds.

It is a further object of the invention to provide a pumping unit of the character aforesaid with reduced tendency to heating and in which cooling is effected by the packing fluid.

Other objects and advantageous features of the invention will be apparent from the description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS The nature and characteristic features of the invention will be more readily understood from the following description taken in connection with the accompanying drawings forming part hereof, in which:

FIG. 1A is a diagrammatic view of a mechanical pumping unit in accordance with the invention;

FIG. 1B is a diagrammatic view of an intensifier pumping unit in accordance with the invention;

FIG. 1C is a diagrammatic view of another intensifier pumping unit in accordance with the invention;

FIG. 2 is a side elevational view of the high pressure cylinders, control valves therefor, cam and return stroke control mechanism in accordance with the invention shown in FIG. 1C;

FIG. 3 is an end elevational view of the structure of FIG. 2 as seen from the line 3-3 of FIG. 2;

FIG. is a horizontal sectional view taken approximately on the line 4-4 of FIG. 2;

FIG. 5 is a horizontal sectional viewtaken approximately on the line 5-5 of FIG. 2;

FIG. 6 is a vertical sectional view taken approximately on the line 6-6 of FIG. 5;

FIG. 7 is a vertical sectional view taken approximately on the line 7-7 of FIG. 5;

FIG. 8 is a diagrammatic view of another form of DESCRIPTION or THE PREFERRED EMBODIMENTS Referring now more particularly to FIGS. 1A and. 10 of the drawings, in which one form of pumping unit is shown diagrammatically, acam 28 is provided.

The shape of thecam 28 and the stroke control structure is described in detail below. Thecam 28 is secured to ashaft 29, driven by acam operating motor 30, an

overload clutch 31 being interposed in theshaft 29. Aspeed controller 32 is provided for themotor 30 so that themotor 30 can be driven at the desired speed and thus determine the rate of feed of the high pressure fluid.

Thecam 28 hasfollowers 26 in engagement therewith carried byguides 33 incylinders 42, thefollowers 26 being urged bysprings 34 into cam engagement. Thecylinders 42 havepump pistons 40 connected to theguides 33.Follower control plates 21 and 22 on threaded adjustingrods 23 are provided to control the return of thefollowers 26 to modify the cam action.

Thepump cylinders 42 havevalve heads 47 secured thereto with inlet anddelivery check valves 48 and 49 connected thereto. Theinlet check valves 48 havefluid connections 50 extending thereto from a source of liquid (not shown) to be pumped, such as a catalyst, to very high pressure with pulseless flow.

Thedelivery check valves 49 have aliquid delivery pipe 51 connected thereto for the delivery of the high pressure liquid. Apressure gage 52 may be connected to thepipe 51 for indicating the delivered pressure.

Referring now more particularly to FIG. 1B of the drawings in which another form of the invention is shown diagrammatically, acam 28 is provided as before, secured to ashaft 29 and driven by acam operating motor 30, an overload clutch 3.1 being interposed in theshaft 29. Aspeed controller 32 is provided for themotor 30 so that themotor 30 can be driven at the desired speed and thus determine the rate of feed of the high pressure fluid.

Thecam 28 hasfollowers 26 in engagement there-- with, carried byguides 74, which engagewedges 75 positioned as hereinafter explained, for controlling fourway valves 76 connected to a supply of fluid under pressure and bypipes 77 and 7.8 to opposite sides of fluid operatedpistons 79 influid cylinders 80. Thepistons 79 are connected to pumppistons 40 in apump cylinder 42. Thepump cylinders 42 have inlet anddelivery check valves 48 and 49 connected thereto. Theinlet check valves 48 havefluid connections 50 extending thereto from a source of liquid (not shown) to be pumped, such as a catalyst, under very high pressure with pulseless flow. I

Thedelivery check valves 49 have aliquid delivery pipe 51 connected thereto for the delivery of the high pressure liquid. Apressure gage 52 can be connected to thepipe 51 for indicating the delivered pressure.

Follower control plates 21 and 22 on threaded adjustingrods 23 are provided to control the return of thefollowers 26 to modify the cam action.

Thewedges 75 are connected bycords 82 extendingoverpulleys 83 and connected for movement with thepistons 79 andpistons 40 to provide a servo action with feedback.

Referring now more particularly to FIG. 1C of the drawings in which another form of the intensifier pumping unit is shown diagrammatically, a reservoir tank for liquid such as oil for the low pressure hydraulic circuit is shown with pumps 11 driven by a motor 12 havingsupply connections 13 extending into the liquid in the tank 10. The delivery connections of the pumps 11 are connected by pipes 14 to fourway valves 15 of well known type, operated by valve operating structure such as operating rods 16.Thevalves 15 havereturn pipes 17 to the tank 10 andpressure relief valves 18 can be connected between thepipes 14 and 17 for excess pressure relief.

Thepipes 14 and 17 can have non-retum orcheck valves 19 and 20 therein to prevent reversal of flow therethrough.

The valve operating rods 16 are preferably spring urged by springs 25 to urge theirfollowers 26 into engagement with acam 28. The shape of thecam 28 and the stroke control structure is described in detail below. Thecam 28 is secured to ashaft 29, driven by acam operating motor 30, an overload clutch 31 being interposed in theshaft 29. Aspeed controller 32 is provided for themotor 30 so that themotor 30 can be driven at the desired speed and thus determine the rate of feed of the high pressure fluid.

A servo action is desired and one suitable structure for the purpose utilizes thevalves 15 which determine the delivery to and discharge of liquid from opposite ends ofmotor cylinders 35. Themotor cylinders 35 preferably haveflexible pipes 140 and 17a connected thereto and thecylinders 35 are preferably mounted for reciprocation and to provide a feed back. Each of themotor cylinders 35 has amotor piston 36 therein with apiston rod 37 extending therefrom through one withcontrol valves 15 as referred to above are only required to generate sufficient pressure to keep thecylinders 35 in position.

The pumps 11 have capacity greater than that required to move thepistons 36, 136 at maximum design speed and excess fluid is diverted through the open centers of the spools of thevalves 15 and or throughvalves 18 if high pressure discharge of the pump is blocked or if closed center spools are used invalves 15, 115.

Each of themotor cylinders 35 is shown as having apump piston 40 extending from the end opposite thepiston rod 37. Thepump pistons 40 are each reciprocable in apump cylinder 42 mounted in ahousing 41 on the frame 38. Thecylinders 42 haveconnections 43 which extend from apump 44 for the supply of the lubricating seal fluid for thepistons 40. Afluid return connection 45 is provided for the return of the lubricating seal fluid.

Thepump cylinders 42 havevalve heads 47 secured thereto with inlet anddelivery check valves 48 and 49 connected thereto. Theinlet check valves 48 havefluid connections 50 extending thereto from a source of liquid (not shown) to be pumped such as a catalyst under very high pressure with pulseless flow.

Thedelivery check valves 49 have aliquid delivery pipe 51 connected thereto for the delivery of the high pressure liquid. Apressure gage 52 may be connected to thepipe 51 for indicating the delivered pressure.

Referring now more particularly to FIGS. 2 to 6 of the drawings, there is illustrated structural details of the principal parts of a preferred form of the unit shown diagrammatically in FIG. 1C.

The fixed frame F has thecam shaft 129 mounted thereon carrying thecam 128.

tion, between lines 0 and a includes the beginning of the constant rate of rise, part of which may be effective on thecam followers 126 to whichvalve actuators 116 are connected. The rise portion of thecam 28 or 128 is accordingly in excess of 180 so that as one cylinder overcomes compressibility and commences discharging fluid the other cylinder is finishing thereby assuring a constant pulseless flow.

The return strokes of thecam followers 126 and theirconnected valve actuators 116 is determined byfollower control plates 121 and 122 which are separately adjustable by their threaded adjusting screws 123 carried in portions F2 of the frame F. Thecam followers 126 are carried on follower blocks 127 with which the overload springs 126 are in engagement, theblocks 127 being urged towards each other by follower block springs 133 for engagement with thecam 128 or the camfollower control plates 121 or 122, dependent on the orientation of thecam 128 and the adjusted position of the camfollower control plates 121 and 122.

In FIGS. 2, 3 and 4 one unit comprisingpump housing 141,pump cylinder 142,motor cylinder 135 and fourway valve 115 is disposed above the other related unit with theupper pump cylinder 142 shown as to the right while thelower pump housing 141, and pumpcylinder 142 is shown as to the left.

Flexible pipes 114a and 117a for supply and discharge of lower pressure fluid are shown.

The valve actuators 116 includevalve actuator plates 154 connected thereto to position the spools of thevalves 115 which in turn control the actuation of the motor pistons (not shown) in themotor cylinders 135.

Themotor cylinders 135 are slidably supported at their outer ends on rods 155.on fixedly carried mounting portions of the frame F and at their opposite ends have drivingyokes 156 extending to crossheads 157 mounted in thepump cylinders 142 for reciprocation. The cross heads 157 have thepistons 140 connected thereto for movement within thecylinder housings 141.

Thepump cylinders 142 havepipes 143 extending throughhousings 141 toradial passageways 143a and circumferential passageways 143b around thepump pistons 140 for the delivery of the lubricating and sealing liquid previously referred to. Passageways 145b and 145a communicate withreturn pipe 145.

Thepump cylinders 142 havecylinder heads 147 secured tohousing 141 in which inlet and delivery valves are provided which can be of any suitable type. US. Pat. No. 3,245,429 to Bacino and Bowen, shows suitable valves.

For some designs, and in order to reduce stress concentration at very high pressures, thepump cylinder heads 147 are essentially flat plates with central portions concaved or convexed with straight bore holes 160 and 161 extending therefrom tosockets 162 in which the inlet and delivery valves are located and to which the supply and delivery connections are connected. The bore holes 160 and 161 are in nonintersecting relation to each other and are so disposed as not to be in the same plane.

Referring now to'FlG. 8, another form of servo action is there illustrated with which a feedback is obtained.

Thecam 28, in Place of thefollower 26, is provided with anidler pulley 226, urged byspring 225 into engagement with thecam 28 and which serves as a cam follower.

Theidler pulley 226 has acable 70 extending thereon to an adjustable end connection 71 to provide a zero adjustment. Thecable 70 extends over anidler pulley 72 to a fixedly located four way motorpiston control valve 215 urged in one direction by a spring 225a. The

'idler pulley 72 is carried by amovable pump piston 240 reciprocatory in a fixedpump cylinder 242. The ratio of movement of the idler pulley-follower 226 to thevalve 215 is one to one which provides a smooth and accurate operation.

Referring now to FIG. 9, another form of servo action is illustrated with which a feed back is obtained.

Thecam 28 has acam follower 326 in engagement therewith. Thefollower 326 is carried on a lever which is normally held against movement by spring stops 76 which may serve as a fulcrum, or the barrels of the spring stops 76 may be attached to therack 81. Thelever 75 is pivotally connected to rack 81, guided byguide rollers 77 with which apinion 78 is in engagement. Arack 79 in engagement with thepinion 78 is held byguide roller 80 and is connected to thecross head 357 to which thepump piston 340, movable inpump cylinder 342, is attached. Thepinion 78 is mounted on and positions amovable valve 315 for motor cylinder positioning.

The mode of operation will now be pointed out.

The pumps 11 are operated by the motor 12, themotor 30 is operated to rotate thecam 28, 128, lubricating seal fluid is supplied by thesources 44, and fluid for pumping is available in thepipe 50.

The movement of thecam 28, 128, is effective to control the positioning of thevalves 15, to supply pressure fluid for the lower pressure hydraulic circuit to actuate thecylinders 35, 135. It will be noted that in FIGS. 1B and 1C the load on thecam 28, 128 is small.

Thecam 28, 128 has a constant rate of rise during the discharge or delivery stroke and upon the return stroke the camfollower control plates 121 and/or 122 become effective, dependent upon their setting, to arrest the return of the pistons. Thepistons 36, 136 will remain at a constant position until thefollowers 26, 126 are again picked up by the advancing rate of rise portion of thecam 28, 128. The adjustment of the camfollower control plates 121 and 122 will determine the length of the stroke of thepump pistons 40, 140 so that when the proper adjustment is made the delivery of pumped liquid by onecylinder 142 will commence just as the delivery from theother cylinder 142 is being completed so that substantially pulseless liquid delivery will be effected.

The adjustment of the cam follower control plates permits adjustment of variable compressibilities of the same fluid at different pressure levels or the variable compressibility of different fluids at the same pressure level.

The use of a hydrocarbon oil, mineral oil or other fluent material having lubricating qualities and the characteristic of becoming substantially more viscous with pressure applied thereon, supplied from thesource 44 through thepipes 43, 143 has been found effective to center thepump pistons 40, 140 and to seal the process fluid against leakage.

Such fluent materials are effective to provide a barrier seal because they heat up as they are subjected to shear when the pistons move. The small amount of heat changes the fluid flowing characteristics of the material and provide a thin film of fluid material for lubrication surrounded by non-moving viscous material which acts as a seal.

Not only is the function of lubrication served, but the use of packings which erode or are eroded is avoided at high pressures of the order of 45,000 psi and higher. Additionally, astraight bore cylinder 142 is achieved thereby reducing stresses to a minimum.

We claim:

1. Pumping apparatus comprising a fluid pump having a pair of cylinders each with a reciprocatory piston and inlet and delivery valves for supply of fluid to said cylinders for pumping by each of said pistons and delivery from said cylinders to a common discharge pipe, and means for actuating said pistons, said means comprising a rotary cam having on its exterior a constant rate of rise portion in excess of 180 for actuation of said pistons in overlapped relation to effect continuous pulseless flow from said cylinders and to said discharge pipe, and means for modifying the action of said cam to accommodate changes in compressibility of the fluid being pumped. 2. Pumping apparatus as defined in claim 1 in which an adjustable speed driving means is provided for rotating said cam. 3. Pumping apparatus as defined in claim 2 in which an overload clutch is interposed in said driving means. 4. Pumping apparatus as defined in claim 1 in which said means for modifying the action of said cam comprises at least one control member for adjustable positioning contiguous to said cam to modify the action of the rise portion of said cam.

5. Pumping apparatus as defined in claim 1 in which operating members are provided for said fluid delivery and discharge valves interposed between said valves and said cam, and said means for modifying the action of said cam comprises at least one slidably mounted control member for engagement with said operating members to modify the action of the return portion of said cam. 6. Pumping apparatus as defined in claim 1 in which said means for actuating said pistons comprises fluid pressure actuated means having reciprocatory members for actuating said reciprocatory pistons, and

control means for said fluid actuated means includmg pressure fluid supply means, and a fluid delivery and discharge valve to which said supply means is connected controlled by said rotary cam and said modifying means. 7. Pumping apparatus as defined inclaim 6 in which said cam has a follower in engagement therewith, and

a feedback connection is provided between said piston and said follower. 8. Pumping apparatus as defined in claim 1 in which said fluid pressure actuated means includes fixedly mounted members and movable members connected to each of said pump pistons, and said movably mounted members and said fluid delivery and discharge valves are mounted for move ment together. 10. Pumping apparatus as defined inclaim 6 in which said control means includes follower members engaged with said cam and to which said fluid delivery and discharge valves are connected, and resilient members for positioning said follower members. 11. Pumping apparatus as defined in claim 10 in which I said resilient members urge said follower members into engagement with said cam. l2. Pumping apparatus as defined in claim 10 in which resilient overload release members are provided in engagement with said follower members.-

13. Pumping apparatus comprising a fluid pump having a pair of cylinders each with a reciprocatory piston and inlet and delivery valves for supply of fluid to said cylinders for pumping by each of said pistons and delivery from said cylinders to a common discharge pipe, and

means including a single rotary cam having on its exterior a constant rate of rise portion in excess of for actuating said pistons in overlapped relation to effect constant pulseless flow from said cylinders at a predetermined compressibility of the fluid being pumped.

Claims (13)

1. Pumping apparatus comprising a fluid pump having a pair of cylinders each with a reciprocatory piston and inlet and delivery valves for supply of fluid to said cylinders for pumping by each of said pistons and delivery from said cylinders to a common discharge pipe, and means for actuating said pistons, said means comprising a rotary cam having on its exterior a constant rate of rise portion in excess of 180* for actuation of said pistons in overlapped relation to effect continuous pulseless flow from said cylinders and to said discharge pipe, and means for modifying the action of said cam to accommodate changes in compressibility of the fluid being pumped.

2. Pumping apparatus as defined in claim 1 in which an adjustable speed driving means is provided for rotating said cam.

3. Pumping apparatus as defined in claim 2 in which an overload clutch is interposed in said driving means.

4. Pumping apparatus as defined in claim 1 in which said means for modifying the action of said cam comprises at least one control member for adjustable positioning contiguous to said cam to modify the action of the rise portion of said cam.

5. Pumping apparatus as defined in claim 1 in which operating members are provided for said fluid delivery and discharge valves interposed between said valves and said cam, and said means for modifying the action of said cam comprises at least one slidably mounted control member for engagement with said operating members to modify the action of the return portion of said cam.

6. Pumping apparatus as defined in claim 1 in which said means for actuating said pistons comprises fluid pressure actuated means having reciprocatory members for actuating said reciprocatory pistons, and control means for said fluid actuated means including pressure fluid supply means, and a fluid delivery and discharge valve to which said supply means is connected controlled by said rotary cam and said modIfying means.

7. Pumping apparatus as defined in claim 6 in which said cam has a follower in engagement therewith, and a feedback connection is provided between said piston and said follower.

8. Pumping apparatus as defined in claim 1 in which means is provided for preventing fluid leakage along said piston, said means including a fluid supply connection to said piston intermediate its ends, and means for supplying to said fluid supply connection a fluent material whose viscosity increases with pressure applied thereon.

9. Pumping apparatus as defined in claim 6 in which said fluid pressure actuated means includes fixedly mounted members and movable members connected to each of said pump pistons, and said movably mounted members and said fluid delivery and discharge valves are mounted for movement together.

10. Pumping apparatus as defined in claim 6 in which said control means includes follower members engaged with said cam and to which said fluid delivery and discharge valves are connected, and resilient members for positioning said follower members.

11. Pumping apparatus as defined in claim 10 in which said resilient members urge said follower members into engagement with said cam.

12. Pumping apparatus as defined in claim 10 in which resilient overload release members are provided in engagement with said follower members.

13. Pumping apparatus comprising a fluid pump having a pair of cylinders each with a reciprocatory piston and inlet and delivery valves for supply of fluid to said cylinders for pumping by each of said pistons and delivery from said cylinders to a common discharge pipe, and means including a single rotary cam having on its exterior a constant rate of rise portion in excess of 180* for actuating said pistons in overlapped relation to effect constant pulseless flow from said cylinders at a predetermined compressibility of the fluid being pumped.

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