US2756562A - Hydraulically actuated surface equipment for pumps - Google Patents

Description

July 31, 1956 R. H. DElTRiCKSON HYDRAULICALLY ACTUATED SURFACE EQUIPMENT FOR PUMPS 2 Sheets-Sheet 1 Filed May 11, 1953 J L w grwc/n'tm Roy H. De/fri (A1500 \iiiik y 1, 1956 R. H. DEITRICKSON 2,756,562

HYDRAULICALLY ACTUATED SURFACE EQUIPMENT FOR PUMPS 2 Sheets-Sheet 2 29 mine 30 Ii ,7 3

Filed May 11, 1953 HEAT EXCHANGE! WATER L l N E5 COM OIL LEVEL (MAX)? PILOT VALVE 5/ 45 UIO DUMP VALVE PUMPING JACK AIR PRESSURE 5 54 37 CONTROLS SHAFT 5 N l s r i eme To MR COMPRESSOR Roy H. Oeifric/rson 2,756,562 Patented July 31, 1956 HY DRAULICALLY ACTUATED'SUR'FACE EQUIPMENT FOR PUMPS Roy H. Deitrickson, Toledo, Ohio, assignor to The National Supply Company, Pittsburgh, Pa., a corporation of Pennsylvania Application May 11, 1953, Serial No. 354,167

8 Claims. (Cl; 60-52) This invention relates to hydraulically actuated surface equipment for pumps of the type frequently used I der or pumping jack in which'th'ere is located a piston that is connected toa pump rod-which usually extends downwardly from the pumping jack and isoperatively linked to the sucker rod' string extending down to the pump itself at the production area level. A hydraulic system for the introduction of working fluid under high pressure into the pumping jack to force the piston upwardly usually includes a mainpump and'ar-r engine for driving the pump, a sump for'provi'ding supply of working fluid, a so-called e'ounterbalanci'rrg tank irrwhi'ch a volume of working fluidis kept under pressure for the storage of energy so that the load on the pump engine can be kept relatively constant duri'ng'both up anddown strokes and the necessary controls, valves and hydraulic lines properly to connect one part of the apparatus with the others.

In a system of this general type various control means must be provided for automatically controlling the connections between the various elements, the operation-of the pump, and the proper pressures and? volumes of both the working fluid and air within the system.

The instant invention: has as its principal object the provision of an automatic fluid level control associated with the counterbalanci-ng tan'kt'o prevent'the' accumulation of an excessive amount'of working fluid .wi'thin the tank and to compensate for leakage of: suchfl-uid from the system and for the purpose of. recirculation, filtering, cooling and cleaning of the oil. In the instant system, a scavenging pump is used which has suction side connected either to the sump or to the: counterbal'ancing, tank depending on the level of fluid. in. the: latter.

It is another object of theinstant invention to provide a hydraulic system. wherein the working fluid. is constantly recirculated. through. filters andheat exchangers and other cleaning and treating apparatuses to: keep it in the proper condition and which 'hasautomatic' means for preventing the accumulation of too large a quantity of such fluid within the energy-storing; counter-balancing tank.

It is yet another object. of this invention to provide apparatus by which a balance of pressure between the pressure of air in the counterbalancing tank and the pressure of this air plus: the weight of a column of fluid is automatically utilized to control the volume of working fluid in the tank, and the invention comprises a novel valve for this purpose.

Other and more specific objects and advantages of the invention will be better understood from thespecification which follows and from thedrawings inwhich:

Fig. 1 is a simplified view, in elevation and on a very small scale, of a surface hydraulic apparatuslfor actuatingthe sucker rod of aproduction pump, certain parts being shown in section.

Fig. 2 is a schematic hydraulic diagram of the main apparatus and lines constituting a surface hydraulic sys temand in particular illustrating the portion of the apparatus embodying the instant invention for automatic fluid level control.

A surface hydraulic system embodying the invention includes a number of conventional structures, the operation of which the invention is designed to facilitate. A surface hydraulic apparatus is designed for the purpose of actuating a piston 10 in its pumping jack 11 which may be erected upon suitable framework 12 extending vertically above a casing 13 of a well. A sucker rod 14 is attached to the piston 10 and extends down the casing 13 where it is connected to the plunger of a pump (not shown) located in the production area of the well. The pumping jack 11 is connected by a main pump line 15 to amain pump 16. The line 15 may be provided with an accumulator pipe 17 (see Fig. l-not shown in Fig. 2) for the purpose of reducing the peak sucker rod stresses by absorbing pulsations in the power fluid beneath the piston 10.

The pump 16 is driven by a shaft 18 (Fig. 2) extending through a shaft tunnel 19 (Fig. l) and connected by suitable clutch means (not shown) to an engine 20.

The pump 16 also is connected by a main tank line 21 to the bottom of a counterbalancing tank generally indicated at 22'. The counterbalancing tank 22 is mounted upon legs 23 and provided with a shut oif valve 24.

In addition: to the main pump 16 the present system includes a constantly driven scavenging pump 25 which "is connected by a scavenging pump output line 26 through an oil filter 27 and heat exchanger 28 to a tank return line 29. The'tank return line 29 is attached to a spray nozzle 30 located at the top of the tank 22 and through which working fluid returned to the tank by the scavengin-g pump 25 is sprayed onto the interior surface of the tank 22. Spraying the working fluid onto the interior surface of the tank 22 at its top provides for thorough washing over the surface of the tank 22 so that the rust and oxidation inhibitors introduced into the working fluid may prevent corrosion and condensation on the inner surfaces of the tank 22.

The scavenging pump 25 has an input line 31 which is connected through an upwardly openable check valve 32 to a main sump 33. The top of the pumping jack 11 also is connected by a line 34 to the sump 33 so that leakage past the jack piston is returned to the sump. Since the hydraulic system operates under a substantial pressure as hereinafter described, leakage is bound to occur at various points, and it is the function of the scavenging pump to make up for these losses.

An air compressor 35 is connected by a line 36 to the upper portion of the tank 22 and functions to maintain pressure within the tank 22.

In general, the apparatus operates as follows: During an up stroke the pressure maintained within the tank 22 forces working fiuid through the line 21 to the main pump 16. The pump 16 raises the pressure on the fluid and pumps it through the main line 15 into the pumping' jack 11. The high. pressure working fluid thus introduced into the pumping jack 11 beneath the piston 10- raises the piston 10 lifting the sucker rod 14 and the column of production fluid located in the casing 13 or in the tubing (not shown) within the casing 13 and delivering a quantity of the production fluid to the top of the well and to the production fluid manifold (not shown) whence it is led to storage or further treatment.

Upon the completion of an up stroke caused by the introduction of high pressure working fluid beneath the pumping jack piston 10, suitable reversing valves are actuated and the fluid within the pumping jack 11 flows back through the main line 15 to the main pump 16 and then with higher pressure added by the main pump 16 is pumped back into the counterbalancing tank 22.

By suitable air pressure control means generally indicated at 37 in Fig. 2 and connected to the tank 22 by an air pressure control line 33, the air pressure within the tank 22 is maintained at a desired level by controlling the operation of the air compressor 35. The pressure within the tank 22 is calculated according to the equation P P r+2 c the pressure to be supplied by the counterbalancing tank. Using these figures, the air pressure control means 37 is so adjusted as to control the air compressor 35 to maintain an average pressure of 400 p. s. i. in the tank 22.

On the up stroke the 400 p. s. i. pressure provided by the tank 22 is added to the additional pressure provided by the main pump 16 in order to overcome the 200 p. s. i. pressure of the sucker rod 14 and the 400 p. s .i. pressure of the column of production fluid, a total of 600 p. s. i. Therefore, the main pump 16 must supply a pressure of 200 p. s. i. On the down stroke the weight of the sucker rod 14 causes a 200 p. s. i. pressure on the input side of the pump 16 and the pump must again add 200 p. s. i. in order to pump the fluid back into the tank 22, the tank pressure being maintained at 400 p. s. i. Thus energy is stored in the tank 22 on the down stroke by the action of the pump and extracted to assist the pump 16 in performing the work of the up stroke.

In the present system, during such operation the scavenging pump 25 also is constantly pumping to draw make-up working fluid from the sump 33 through the check valve 32 to pump it through the output line 26, oil filter 2'7 and heat exchanger 28 to the tank line 29 and into the tank 22. While the scavenging pump 25 delivers a higher pressure than the pressure within the tank 22 so that the make up fluid can be introduced into the tank 22, the volume delivered by the scavenging pump is relatively small. It produces, however, a recirculation of all of the fluid in the system thus filtering and cooling the fluid to keep it in good condition.

When, as frequently occurs, the scavenging pump has been pumping fluid into the tank 22 continually for some time the level of working fluid within the tank 22 may rise above a maximum desired level. Apparatus embodying the instant invention is designed to prevent the level of working fluid from reaching a point above such a desired maximum. It will be appreciated that the level of fluid in the counterbalancing tank is constantly moving up and down and the liquid therein is highly agitated due to the rapidity with which it is withdrawn and returned. Thus, ordinary liquid level controls are inadequate to determine the maximum fluid level, and some device not subject to the rapid and turbulent fluctuations must be used.

A working fluid level sensing pipe 39 is connected to the tank 22 at the maximum fluid level. The line 39 extends downwardly in order to provide for a head of fluid in the pipe 39 and is connected to a fluid level pilot valve generally indicated at 40 leading to a chamber 41 beneath a pressure responsive member such as a diaphragm 42. The chamber 41 beneath the diaphragm 42 communicates through a port 43 with a pocket 44 in the bottom of the pilot valve 40. The pocket 44 is connected to a line 45. Any suitable diaphragm actuated valve such as a plunger 46 extending downwardly from the diaphragm 42 and into the pocket 44 may serve as a valve for the line 45.

In the preferred form, a chamber 47 above the diaphragm 42 is connected by a short line 48 to the air line 38 leading to the tank 22 so that the pressure on the upper side of the diaphragm corresponds to the pressure in the tank. The line 48 may be so designed as to constitute a trap in order to prevent droplets of working fluid carried out of the tank through the air line 38 from accumulating in the chamber 47 above the diaphragm 42.

Air pressure within the tank 22 thus is applied to the upper side of the diaphragm 42 holding the valve plunger 46 down in valve closing position and preventing the flow of any fluid out of the lower chamber 41 into the line 45. A small coil spring 49 may be placed above the diaphragm 42 in order to add its thrust to the pressure of the air in the line 38 to hold the diaphragm 42 and the plunger 46 down. There is, in addition a pressure down on valve 46 due to the differential area created by the seated valve, the pressure being equal to the area of the valve times the air pressure on the diaphragm (which air pressure is the same on both the upper and lower sides).

When the level of working fluid within the tank 22 reaches the point of connection of the pipe 39, the pipe 39 is filled with the Working fluid. The pressure created by the head of fluid is added to the pressure within the tank 22 (also present in the lines 38 and 48 and above the diaphragm 42) and, being applied beneath the diaphragm 42, it moves the diaphragm 42 upwardly lifting its valve plunger 46 and opening the line 45. The working fluid in the line 39 flows into the line 45 and into a fluid dump valve 50 beneath a valve piston 51 lifting the piston 51 and its plunger 52 to place a tank branch line 53 in communication with a scavenging pump intake branch line 54. When these two lines are placed in communication the constantly operating scavenging pump now withdraws Working fluid from the main line 21 and pumps it directly into the scavenging pump output line 26 and the upper tank input line 29. The presence of the working fluid in the line 54 at the counterbalancing tank pressure closes the check valve 32 and no additional fluid is withdrawn from the sump 33 while the fluid dump valve 50 is open; the fluid in the tank 22 being directly recirculated.

This direct recirculation of fluid out of and into the counterbalancing tank 22 by the scavenging pump 25 continues as long as the maximum level of working fluid in the tank 22 remains above the connection point of the fluid level sensing line 39 so that fluid can flow into the pipe 39. When an up stroke of the pumping jack, for example, causes the withdrawal of a sufficient quantity of working fluid from the tank 22 to lower the working fluid level, no further working fluid flows into the line 32 and the head of fluid in the line 39 alone holds the pilot valve 40 open so that the valve 40 does not operate at each stroke. During all of the time when the pilot valve 40 is held open fluid is bled from the line 45 through a bleeder valve 55 directly to a sump line 56. During this time also leakage is occurring in the remainder of the system and is not being made up by the scavenging pump. Therefore, when the level of fluid in the tank 22 drops below the level of the connection of the fluid sensing line 39, no further fluid flows into the line 39 and the fluid in the line 39, the pilot valve 40 and the line 45 gradually bleeds away through the bleeder valve 55 and sump line 56. After a period of time controlled by the setting of the bleeder valve 55 the pressure within the line 45 drops to such a point that the pilot valve stem 46 is thrust downwardly into closing position.

When the pilot valve 40 closes, continued bleeding of fluid past valve 50 soon causes this valve to close also and the scavenging pump 25 no longer can draw work ing fluid through the lines 53 and 54 and the check valve 32 opens so that fluid is withdrawn from the sump 33 by the scavenging pump 25, and direct recirculation from and to the counterbalancing tank ceases until the level therein again rises enough to fill pipe 39 to such a point that the weight of the column of liquid therein causes the valve 40 to open.

Additional lines and apparatus, some shown in the drawings, as, for example, an air chamber 58, air compressor control line 59 and other apparatus not shown in the drawings, is provided for accomplishing conventional controls and operation cycles well understood in the art, the instant invention being solely concerned with automatic fluid level control instigated by excessive fluid level in the tank and operative to effectuate recirculation thereof, providing for cleaning, cooling and other treatment of the working fluid as well as eventual lowering of the working fluid level.

What I claim is:

1. In a hydraulic system for operating a pump, a counterbalancing tank, a working fluid sump, a constantly operating scavenging pump having its outlet connected to said counterbalancing tank, a pressure responsive normally closed pilot valve that is subjected to and opened by extra fluid pressure present only when the contents of said counterbalancing tank exceed a predetermined maximum level, and a second valve opened by said pilot valve and operable when open to connect the suction side of said scavenging pump to said counterbalancing tank to recirculate fluid thereto, the suction side of said scavenging pump being connected to said working fluid sump when said second valve is closed.

2. Apparatus according to claim 1 and means to bleed away said extra fluid pressure from said pressure responsive valve when open.

3. In a hydraulic system for operating a pump, a counterbalancing tank, a working fluid sump, a constantly operating scavenging pump having its outlet connected to said counterbalancing tank, a pressure responsive normally closed pilot valve having one side subject to air pressure in said tank and its opposite side subject to such air pressure and to an extra pressure created by fluid in said tank only when the contents of said counterbalancing tank exceed a predetermined maximum level, and a second valve opened by said pilot valve and operable when 0pc". to connect the suction side of said scavenging pump to said counterbalancing tank to recirculate fluid thereto, the suction side of said scavenging pump being connected to said working fluid sump when said second valve is closed.

4. Apparatus according to claim 3 and means to bleed fluid from the side of said pilot valve subject to fluid pressure.

5. In a hydraulic surface system for vertically reciprocating a well rod, which system includes a hydraulic cylinder, a rod piston in said cylinder, a pump in communication with said cylinder at a point on the working side of said piston, :a counterbalancing tank in series with said pump :and said cylinder and an engine for driving said pump, for pumping working fluid from said tank into said cylinder and from said cylinder into said tank -for raising and lowering said piston, the improvement in means for controlling the level of working fluid in said tank comprising, a fluid line connected to said tank at the maximum level desired for the working fluid therein, an air line connected to said tank at a level substantially above the maximum level of such working fluid, valve means connected to both said fluid and air lines and responsive to the balance of pressure resulting from fluid in said fluid line and air in said air line for opening said valve means, a third line connected to said valve means and in communication with said fluid line when said valve is open, a dump valve connected to said third line and actuated to open by fluid pressure therein, a sump, 1a scavenging pump constantly driven by said engine andhaving an output pressure above the pressure maintained in said tank, an output line connecting said scavenging pump to said tank, an input line having a check valve :and connecting the suction side of said scavenging pump to said sump, a branch line connecting the bottom of said tank to said dump valve, and a second branch line connecting said dump valve to the suction side of said scavenging pump between said check valve and said .pump, said branch lines being in communi cation only when said dump valve is open, whereby fluid is pumped from said sump into said tank by said scavenging pump when said dump valve is closed and recirculated through said branch lines and said pump to said tank when said dump valve is open.

6. Apparatus according to claim 5 in which said fluid line extends downwardly from said counterbalancing tank and said valve means is located at .a level below said counterbalancing tank whereby said valve means is responsive to the head of working fluid in said fluid line.

7. Apparatus according to claim 5 and an adjust-able 'bleeder valve connected to said third line between said valve means and said dump valve, whereby the pressure of fluid in said fluid line, and said third line is reduced through said bleed er valve.

.8. Apparatus for controlling the maximum level of liquid in a tank under controlled, constant air pressure in which liquid is rapidly withdrawn and replaced, comprising a dump valve for said tank, a pressure responsive member subject on one side to the air pressure in said tank and subject on a second side to such air pressure and to an additional pressure created by liquid in a vertical liquid level line connected to said tank at such maximum level, a pilot valve that is opened by said pres sure responsive member in response to the head of liquid in said liquid level line for connecting said liquid level line to said dump valve for applying tank pressure through said liquid level line for opening said dump valve and for holding said dump valve in open position, and means operable when said pilot valve is open to discharge liquid creating such additional pressure at a controlled rate from said liquid level line.

References Cited in the file of this patent UNITED STATES PATENTS 1,056,044 Muchk-a Mar. 18, 1913 1,547,429 Ludeman July 28, 1925 1,766,666 Meyer June 24, 1930 2,393,119 Paasche Jan. 15, 1946 2,586,410 Williams Feb. 19, 1952

Images