US2240775A - Control system for pipe lines - Google Patents

Description

May 6 1941- i w. G..HE|.-TZEL Erm. 2,240,775

CONTROL SYSTEM FOR *PIPE LINES John Ry Po/son BY/e/ZM ATTORNEY May 6, 1941. w. G. HELTzEL Erm.

CONTROL SYSTEM FOR PIPE LINES Filed April 4, 1938 2 Sheets-Sheet 2 n wm m@ 0eam- ../HH Mmmm n nwwfm l 8 O Gsw/MU MMJR A Mmm/w wim Patented May 6, 1941 CONTROL SYSTEM Foa PIPE LINES- William Gillum Heltzel, Jennings Bryan Harsh' man, and Joh-n Ray Polston, Tulsa, Okla., assignor's to Stanolind Pipe Line Company, Tulsa, Okla., a corporation of Maine Application April 4, 1938, Serial N0. 199,760

4 Claims.

This invention relates to pipe lines, and more particularly to pipe lines for the transportation of fluids for long distances. Still more specifically it relates to a method and apparatus for automatically controlling the pumping rate of a pumping station in such a pipe line.

In the operation of pipe line systems, and especially of such systems for the transportation of crude oil, it is the general practice to maintain a number` of pumping stations along the line a considerable distance apart, in each of which the pumping rate is manually controlled. It has been found necessary in using this system to have tanks located at each station connected to the incoming line to receive the'excess oil when the up-stream station is pumping at a faster rate f than the down-stream station, and conversely to supply oil to the down-stream station when its pumping rate is greater than that of the upstream station. One undesirable feature of this arrangement is the necessity of constantly adjusting the pumping rates at all .of the stations, and another is that the amount of oil in the station tanks fluctuates widely and often, thus resulting in high losses of volatile fractions from the oil in the tanks "by evaporation.

It is anobject of our invention to provide a methodof automatically controlling the pumping rate at a pipe line pumping station so that it is substantially.synchronized with` that of the adjacent up-stream station. Another object is` to provide means for controlling the pumping rate at a pipe line pumpingl station in accordance with the pressure of the incoming fluid. Still another object is to provide an improved -ap- 'fparatus for controlling the speed of an engine by hydrostatic pressure.

Further objects will be apparent `from the following detailed descriptiongreadin conjunction with the drawings, in which:

Figure l shows diagrammatically a pipeline pumping station equipped With'ourimp'rovedcontrol system; and Vj' V 'l Figure 2 shows ,a view 'inf' elevation'fand partly in cross-sectionofavr preferred form l. cffour improved control system. i

Our invention inlits broadest aspects canV best beunderstood -by' reference to Figure 1,`in which III represents a pipe-line -carrying'a flyidffromtthe adjacent up-stre'am pumping'` st tiony to the pumping station'which is representedv by theV figure; Since our invention--is-particularly applicable to'oil pipe lines, although 'not limited thereto, we w'ill hereafterr'efer toJ oil asfthe fluid being pumped." v'I'he-oil-arriving through line III enters f suction header Il, and then passes through suction lines I2, I3, I4 and I5 to pump units'IG, I`l,

I8 and I9, respectively. Valves 20, 2l, 22 and 23 are provided in lines I2, I3, Il and I5, respectively, so that one or more of the pump units may .be shut downwhen the amount of oil to be pumped can be handled by less than all of the units.

Each pump unit consists of a prime mover, such as a Diesel, gasoline or steam engine, or an electric motor, and a pump, which may be of the reciprocating or centrifugal type. The'oil which has hadA its pressure increased by pump units I6, I1, I8 and I9 is discharged through discharge 15, 1ines 24, 25, 26 and 21, and valves 28, 29, 30 and 3l, respectively, into discharge manifold 32,- from which it is further discharged through line 33 to the next down-stream pumping station on the pipe line.

Incoming line I0 is also connected by means of line4 35, `vvhichis controlled by valve 36. Valt/,e36 is of a type which does not allow oil to flow into tank 34 unless the pressure in line I0 exceeds va predetermined value but allows oil to flow from tank 34 into line IIL-when the head ofvoil in the former exceeds thepressure in the latter. A suitable valve for 'this purpose is that describedin U. S. Patent 2,098,014, granted on November 2, 1937, to J. R. Polston.. a 1

Y vA small pipe line 31equippedwithvalves'n and 39 connects suction header `II land our im- "proved control device-40, Whichis shown installed on pump-unit I9.- lBy means of this device, 4one embodiment of which will hereinafter be described in. detail, the speed of the engine driving the pump in this unit -is increased as the pressure in suction header II increases, and vice versa, so' that the amount of oil discharged-from the stationis equal to that arriving from the next up-stream-Istation.l It apparent, there.- fore, that when ja Aseries of pipe .line .pumping stations is equipped withcour controlsystem, `.variations in' rate of discharge -from the. up stream station will-.automatically vary -that ,of the successive down-stream stations so, that `no oil n'eed be introduced into`l or:withdra,wn-from the station tanks.- f f ,sw

InV order for the -control systeni-y torunction properly, it is essential that the: pressure atwhich valve 36 allows oil' to flow-into tank. be greater than that' which'exis'ts in suctionj headerl I.; @The actual lpressures-'used maynvaryponsiderably dejpending upon localy conditions,but,v ing., general satisfactory 'operation is vobtained when4 valve 3 6 is set to operate atabout20 .pounds per square inch and control 40 is set to operate when the pressure in suction header ranges from about 3 to about 15 pounds per square inch, with maximum engine speed and therefore maximum pumping rate at the highervalue. If the oil is arriving at the station vat a rate which exceeds its capacity, control `40 increases the pumping rate to capacity, and the pressure in suction header increases to 20 pounds per square inch,

so that valve 36 opens and the excess oil flows into tank 34. If the incoming oil rate then decreases to a value Within the capacity of the station, the pressure in suction header Il falls below 20 pounds per square inch, thus causing valve 36 to close, and then below-15 pounds per square inch, thus causing control 40 to become operative and adjust the pumping rate to the incoming oil rate. If the incoming oil rate falls control. For most purposes, however, automatic control of one.-` pumping unit is ksuilcient to take care of the usual variation in oil flow through al pipe line.

Wel will now describe in detail our improved control apparatus; Referring therefore to Figure -2, cylinder 4| is provided with a chamber 42 at its lower end with an axial opening 43 between the latter and the interior of cylinder 4|. The

- lower-portion of chamber 42 has a horizontally extending bracket 44 and cylinder 4| has a bracket 45 attached thereto so that the control mechanism may be supported in operable' relation to the engine of a pumping unit.

.A pipe connection 46 communicating with chamber 42 is provided with a drain pipe 41, controlled by a valve 48, and avalve 38 which is connected to pipe line 31 leading from. suction header (Fig. 1) A stuffing box 49 is provided travel of piston assembly 56, and a. shield 12 secured by cap screws 66 to prevent inadvertent interference with stop bolts 10.

Upper spring seat 68 hasan axial bore 13 and an upwardly-facing depression adapted to receive ball-bearing 14. A shank 15, which rests upon ball-bearing 14 and extends through an opening 16l in housing 64, has aixed to its upper end an adjusting wheel 11 and adjacent its lower end is provided with a threaded bore 18. Rod 54, which is adapted to pass Without friction through housing 53, tube 63 and bores 5B and 13, is threaded at its upper end and is operably mounted in threaded bore 18. Locking wheel 19 is provided on rod 54 to cooperate with shank 15 to maintain rod 54 in a desired position with respect to shank v15.

The lower portion of rod 54`is also threaded and may be connected by any suitable means to the usual mechanism for changing the speed of a prime mover. For instance, it may be connected at the bottom of chamber 42 which contains packing material held in place and compressed by packing ring 5| and packing gland nut 52. A housing 53 is attached to nut 52 to prevent injury to. rod 54 which will be described in subsequent paragraphs. Cylinder 4| is'tted with a. replace able liner 55, preferably of brass or other metal not readily attacked by crude oil, in which a piston v*assembly 56 is adapted to -move vertically. Piston assembly 56 is composed of a member 51 having a 'vertical bore 58 therethrough and an outwardly threaded raised portion 59 for the reception of leather cup 68, disc 6| and lower spring seat 62. Member 51 also supports a depending vertical tube 63, preferably of brass, which passes through opening 43 with considerable clearance and through stufling box, in which the packing 56-is such that tube 63Jmay slide vertically 'without substantial loss of liquid.

Housing 64 is attached to flange 65, which is f to the throttle of a steam, gasoline or gas engine,

a resistance in an electric motor circuit, ortothe fuel pump of a Diesel engine.l In any case, there must be a force tending to move rod 54 downward Yso that spring 69 is compressed and this may suitably be accomplished by means of a spring in the system.

For purposes of illustration, however, we have shown in Figure 2 an 'arrangement for controlling the speed of a Diesel engine. A lever pivoted at 8| is attached at one end to the lower end of rod 54 by means of link connection 82, and at the other to a link 83 which is in turn attached to a forked lever 84 pivoted at 85. Adjacent link 83, lever 84 engages pins 86 on governor slip collar 81 so that changes in the position of the governor, [which is of a conventional type enclosed by governor bowl 88, moves slip collar 81 and forked lever 84. Adjustable link 89 is attached tothe other end of forked lever 84 and te bau crank so of the fuel pump s l, which regulates the effective length of stroke of the pump plunger, and consequently the speed of the engine and the pumping rate of the unit.

We will now describe the operation of our cony trol system in connection withA the embodiment shown in Figure 2. Valve 38 is opened and valve 48 closed so rthat the pressure in suction header is `transmitted through line 31, valve 38, chamber 42 and opening 43 into cylinder 4|, in which it is exerted against piston assembly 56, causing the latter to move upward and compress spring 69. Upper spring seat 68 and thereforerod consequently tend to move upward, but this motion is opposed by aforce acting downward on rod 54, which may be that exerted by a spring in an obvious manner, but which in the embodiment shown is the force exerted by the governor in bowl 88 when it is displaced from its normal positionfor a particular engine speed acting through slip collar 81, pins 86, lever 84, link 83, lever 80 and lipkr8'2. This force increases with the displacement Vof rod 54, so that a given displacement of piston assembly 56 causes a much smaller displacement of rod 54. It is seen therefore that an increase in pressure in suction to the bell crank $8 through linkv82, lever 88,`

link 83, lever 84 and link 89, thereby increasing the eifective stroke of fuel pump 8|, the speed of the engine, and the pumping rate of the unit so as to compensate for the increased flow of oil to the station.

The characteristics of spring 69 depend upon the particular conditions under which the control is to operate. In one .installation of the type shown on a pumping unit equipped with a Dieselengine having a minimum speed of 186 R. P. M. and a maximum speed of 257 R. P. M. at full load, this variation in speed is obtained when rod 54 moves three-eighths of an inch, and the force whichmust be overcome to cause this movement is 285 pounds. `The area of piston assembly 56 is 23.8 square inches, so that the entire movement is obtained when the pressure in cylinder 4| varies from 0 to about 12 pounds per square inch. Spring 69 compresses about one inch for each 69 pounds exerted on it, and con-` sequently is compressed about 4% inches as the pressure in cylinder 4I is varied over this range. The total travel of piston assembly 56 is therefore about 41A inches, and the stop bolts 10 are adjusted so as to limit the piston travel to this value and avoid overworking the engine. In this installation the height of cylinder 4l is such that the pressure therein is 3 pounds per square inch less than in suction header Il, so that when the pressure in suction header Il varies from 3 to 15 pounds per square inch, the pres- Cil sure in cylinder 4I varies from zero to 12 pounds Y per square inch.

Another feature of our improved control device is the ease with which it may be changed over to manual adjustment. To accomplish this, it is only necessary to close valve 38, open valve 48 so as to relievethe pressure in cylinder 4| and allow piston assembly ,56 to rest uponV the lower end thereof, turn adjusting wheel 11 until the engine speed and pumping rate are at the desired value, and lock wheel 11 inplace with locking wheel 1s.

While we have described our invention in connection with a specific embodiment thereof, we do not desire to be limited thereto, but only 1 by the scope of the following claims.

We claim:

1. In a control system for pipe line pumping I said piston, and means actuated by said control member for regulating the speed of .said prime mover.

2. In a control system for pipe line pumping stations including a prime mover, a pump driven by said prime mover and a iluid inlet to said ated by said piston for moving said control meml ber, means for urging said control member against said resilient means, and means actuated by said control member for regulating the speed of said prime mover.

3. In a control system for pipe line pumping stations including aprime mover having a govvernor, a pump driven by said prime mover and a fluid `inlet to said pump, the combination which comprises a cylinder, a piston adapted toreciprocate within said cylinder, means for subjecting one face of said piston to the pressure in said fluid inlet, whereby said piston moves in accordance with said pressure, a control member, a spring actuated by said piston adapted to move said control member, means actuated by said governor for urging said control member against said spring, and means actuated by said control member for regulating the speed of said prime mover.

4. In a control system for pipe line pumping stations including a prime mover, a pump driven by said prime mover and a fluid inlet to said pump, the combination which comprises a cylindrical chamber, a piston adapted to reciprocate within said chamber having an axial opening therethrough and a depending axial tube of a length such that its lower end-extends below the bottom of said chamber, means for subjecting the lower side of said piston to the pressure in said uid inlet, an elongated control member extending through said tube and said axial opening in said piston, a spring actuated by said piston tendingto raise said control member, means for urging said control member against said said cylinder, means for. subjecting one face of spring, and means actuated by the lower portion of said control member for regulating the speed of said prime mover.v

WILLIAM Grimm HELTZEL. JENNINGS BRYAN JOHN RAY roLs'roN.

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