US3708239A

US3708239A - Means and method of regulating flow from centrifugal pumps

Info

Publication number: US3708239A
Application number: US00183138A
Authority: US
Inventors: M Stahle
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-10-16
Filing date: 1971-09-23
Publication date: 1973-01-02
Anticipated expiration: 1990-01-02
Also published as: DK134197B; DK134197C; SE369217B; AU452721B2; CH533242A; FI51630B; GB1364304A; JPS549321B1; NL166311C; AU3456271A; DE2147147A1; CA931042A; FI51630C; NL166311B; FR2109850A5; NL7113381A; DE2147147B2

Abstract

The flow regulating means includes a regulator shell having a tangentally placed inlet tube at its lower closed end, the upper end being open. The shell is submerged at a level below the normal level of the liquid to be pumped. The shell receives a concentrically disposed suction pipe connected with the intake of a centrifugal pump. In the exercise of the method, when the level of the liquid body is above the shell a predetermined distance, the liquid is drawn downwardly in the shell around the suction pipe, then upwardly through the suction pipe with minimal turbulance so that the pump operates at maximum capacity. When the liquid approaches the top of the shell, an increased volume of liquid enters the tangent inlet tube to produce a vortex which increases in force as the liquid level subsides to cause proportionately decreasing pump capacity, tending to produce an equilibrium between liquid input and pump output.

Description

United States Patent Stahle 1 51 Jan. 2, 1973 s41 MEANS AND METHOD OF 3,024,730 3/l962 Towle ..417 424 L IN L W FROM 3,434,430 3/[969 Berman =1 al. ..415 24 CENTRIFUGAL PUMPS Primary Examiner-C. .l. Husar [76] Inventor: tiarltlinsstitlzhlel, P80. Box 12, Neun- Attorney chafles G140 et M Ito W1 er an 22 Filed: Sept. 23, 1911 [571 ABSTRACT [21] Appl. 183438 The flow regulating means includes a regulator shell having a tangentally placed 1nlet tube at its lower closed end, the upper end being open. The shell is [30] Foreign Application Priority Data submerged at a level below the normal level of the liquid to be pumped. The shell receives a concentri- Switzerland Una/70 cally disposed suction pipe connected with the intake of a centrifugal pump. in the exercise of the method, [52] [1.8. CI. AIS/1, 415/24, 44ll77lll47zld when the level of the liquid body is above the She" a 5 I t Cl Fold 17/00 predetermined distance, the liquid is drawn I7 24 downwardly in the shell around the suction pipe, then 1 e 0 re l 7/ upwardly through the suction pipe with minimal turbulance so that the pump operates at maximum [56] Referenc C'ted capacity. When the liquid approaches the top of the UNITED STATES PATENTS shell, an increased volume of liquid enters the tangent inlet tube to produce a vortex which increases in force 1,460,428 7/1923 Moody ..4l5/1 as the liquid level subsides to cause proportionately l,529.634 3/1925 Nagler .14lS/24 decreasing pump capacity, tending to produce an fr 25i: equilibrium between liquid input and pump output. au ..4l |,9l4,926 6/1933 Pfau .415/24 7 Claims, 3 Drawing Figures MEANS AND METHOD OF REGULATING FLOW FROM CENTRIFUGAL PUMPS BACKGROUND OF THE INVENTION The usual procedure for removing liquid from a pump or other body of liquid, which is being simultaneously filled either intermittently or constantly, is to provide a centrifugal pump having a capacity which exceeds the inflow rate of liquid so that, when the pump is operating, the liquid level recedes. Then, when the liquid surface reaches some selected level, a level sensing switch shuts off the pump. A second switch turns the pump on when a maximum level is reached and the cycle repeats. In many cases, such intermittent electrical control is undesirable, it may be a source of malfunction, it may be an electrical hazard if the liquid is inflammable, or it may be an extra expense.

SUMMARY OF THE INVENTION The present invention is a means and method of regulating flow from a centrifugal pump which overcomes the disadvantages of operating a pump intermittently, and is summarized in the following objects:

First, to provide a means and method of regulating centrifugal pumps which eliminates or minimizes the need or frequency of use liquid level sensing switches or other electrical control, instead, regulation being accomplished by controlling the capacity of the pump, thereby controlling its output rate, so as to match the liquid input rate.

Second, to provide a regulating means and method, as indicated in the preceeding object, accomplishes control without moving parts or electrical elements and at minimal cost.

Third, to provide a regulating means and method as indicated in the preceeding objects, which utilizes a fixed regulator shell surrounding the suction pipe connected with the pump, the shell being open at its upper end and submerged in the liquid to be pumped at a depth below the intended upper level, the shell having a tangently positioned inlet pipe which is operable when the liquid level passes below the upper end of the shell to produce a vortex in the liquid entering the suction pipe, the vortex having the effect of reducing the capacity of the pump, the vortex force increasing as the liquid level subsides causing further reduction in capacity until liquid output counterbalances liquid input.

[N THE DRAWINGS With reference to the drawings:

FIG. 1 is a top view of a centrifugal pump and the regulating means, with portions in section.

FIG. 2 is a partial side view, partial sectional view thereof, the sectional portions being taken through 2- 2 of FIG. 1.

FIG. 3 is a diagrammatical view illustrating the velocities at the inlet of the centrifugal pump as produced by the regulating means and method in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT A conventional centrifugal pump 1 is provided with a suction pipe 2 having a flared lower end 3. Surrounding the suction pipe 2 is a regulator shell 4, including a cylindrical wall 5 closed at its lower end by a bottom wall 6, the upper end being open. lntersecting the shell wall 5 tangently is one or more inlet tubes 7, having a flared end 8. Liquid entering the shell 4 from the inlet tube 7 rotates in die same direction as the centrifugal pump 1.

The regulator shell 4 is submerged with its upper end a predetermined distance below the intended maximum level of the liquid, indicated by x. The outer and inner ends of the inlet tube 7 are indicated by a" and b" respectively. The internal diameter of the suction pipe 2 is indicated by d" whereas the inside diameter of the shell 4 is indicated by D". The distance from the flared bottom of the suction pipe 2 is approximately the same as the inside diameter of the inlet tube 7.

When the surface of the liquid is in the level indicated by x", the pressure difference between the upper end of the regulator shell 4 and the receiving end of the suction pipe 2 is minimal. Consequently, the pressure difference between 0" and b is also minimal, and no significant flow of liquid occurs through the inlet tube 7; thus, little or no vortex or rotational flow of liquid occurs below the suction pipe 2. Instead, flow is essentially axially downwardly within the regulator shell 4, then axially upwardly in the suction pipe 2 with the result that the pump 1 operates with maximum capacity, delivering the maximum volume of liquid.

Improved operation is obtained by flaring the ends of the suction pipe and inlet tube as indicated by 3 and 8. Also, it is preferred that the suction pipe 2 be spaced from the bottom wall 6 a distance approximating the inside diameter of the inlet tube 7; and that the inside diameter of the suction pipe 2 be greater than the inside diameter of the inlet tube 7.

If the liquid surface subsides from the level .r", reducing the distance between the liquid surface and the upper end of the regulator shell 4, a corresponding loss of pressure occurs at the entrance end of the suction pipe 2. This causes increase in pressure differential between ends a and "b" of the inlet tube 4 so as to increase flow through the inlet tube 7 into the regulator shell 4. Due to the tangential position of the inlet tube 4, which corresponds to the direction of rotation of the centrifugal pump, rotational or vortex movement of liquid within the regulator shell 4 increases, causing a corresponding rotational or vortex movement in the suction pipe 2. As a consequence of this turbulance, the volume of liquid discharged by the pump is reduced. This decrease in pump capacity is proportional to the peripheral velocity of the liquid entering the pump.

Once the level of the liquid subsides below the upper end of the regulator shell, all liquid must enter through the tangential inlet tube 7 causing an increased vortex within the shell until a maximum is reached when the water is a distance Ah" below the upper end of the shell. At some level below 1'', depending upon the rate of input to the liquid body, the capacity of the pump diminishes until its output matches the input of liquid, and tends to maintain the liquid at a constant level, unless the liquid input rate should rise or fall. However, the pump may lag in recovering its capacity permitting the liquid level to rise. in this case, the liquid level will fluctuate between a maximum and minimum level. The relative proportions of regulator chamber and length, suction pipe diameter and length are so determined that the pump does not run dry and thus require priming, [f it is desired to extend the transition zone between minimal to full flow of liquid through the inlet tube 7, the upper end of the shell 4 may be appropriately inclined or slotted.

The effect of the tangential inlet tube 6 may be expressed mathematically. Since V.R equals a constant, rotation generated in the shell will continue inside the suction pipe 2, the peripheral velocity inside the suction pipe being equal to:

V. D/d

where:

V= Peripheral velocity D inside diameter of the shell 4 d= inside diameter of the suction pipe 2 The effect of rotational or vortex velocity is indicated in the triangle of velocities represented in FIG. 3, in which:

B, blade pitch u blade peripheral velocity C,,,, normal maximum water-raising speed C, peripheral velocity of rotating liquid entering the pump C, the reduced water-raising speed acquired by C,,.

The means and method for pumping liquid described works automatically, is simple to manufacture, requires no servicing and on account of the total absence of moving parts, is completely free from false or faulty performance.

While a particular'embodiment of this invention has been shown and described, it is not intended to limit the same to the details of the construction set forth, but instead, the invention embraces such changes, modifi cations and equivalents of the various parts and their relationships as come within the purview of the appended claims.

lclaim:

l. A method of regulating the withdrawal of liquid from a body of liquid utilizing a centrifugal pump having a maximum output exceding the inflow of liquid to the liquid body, the method characterized by:

a. causing an essentially vortex-free flow of liquid to the pump when the surface of the liquid body is above a predetermined level, thereby to produce maximum output from the pump tending to cause the surface of the liquid to subside;

b. and causing increased vortex-flow of liquid to the pump as the surface of the liquid subsides below the predetermined level, thereby to produce a decreasing output from the pump until the surface level ceases to subside.

2. A method as defined in claim 1, wherein;

a. essentially vortex-free flow is caused moving the liquid axially downwardly between a pump suction pipe and a surrounding shell and then upwardly to the pump through pipe;

b. vortex flow 'is caused by introducing liquid tangently into the bottom of the shell below the inlet to the pipe.

3. Means for controlling the surface level of a body of liquid which receives a inflow of liquid, comprising;

a. a centrifugal pump aving a maxlmum output in excess of the liquid inflow;

a first means operable to produce an essentially vortex-free flow to the pump, when the surface of the liquid body is above a predetermined level, thereby to produce a maximum output from the pump tending to cause the surface of the liquid to subside;

. a second means operable to produce increasing vortex-flow to the pump, as the surface of the liquid subsides below the predetermined level, thereby to produce a decreasing output from the pump tending to match the inflow of liquid.

4. A controlling means as defined in claim 3,

wherein:

a. a suction pipe depends from the pump and terminates in an inlet submerged in the body of water;

b. the first means is a shell surrounding the suction pipe, having a closed lower end spaced below the suction pipe inlet as well as below the intended lower level of the liquid body and an open upper end below the intended level of the liquid body whereby flow of liquid into the upper end of the shell tends to produce flow of essentially vortex free-liquid to the suction pipe;

c. the second means is at least one tangently disposed inlet near the bottom of the shell tending to produce increasing vortex flow into the suction pipe as the liquid level subsides.

5. A controlling means as defined in claim 4,

wherein:

a. the inlet end of the suction pipe is spaced above the bottom of the shell a distance approximating the inside diameter of the inlet tube.

6. A controlling means as defined in claim 4,

wherein:

a. the inside diameter of the suction pipe is larger than the inside diameter of the inlet tube.

7. A controlling means as defined in claim 4,

wherein:

a. the inlet ends of the suction pipe and inlet tube are flared.

i b i i i

Claims

1. A method of regulating the withdrawal of liquid from a body of liquid utilizing a centrifugal pump having a maximum output exceding the inflow of liquid to the liquid body, the method characterized by: a. causing an essentially vortex-free flow of liquid to the pump when the surface of the liquid body is above a predetermined level, thereby to produce maximum output from the pump tending to cause the surface of the liquid to subside; b. and causing increased vortex-flow of liquid to the pump as the surface of the liquid subsides below the predetermined level, thereby to produce a decreasing output from the pump until the surface level ceases to subside.

2. A method as defined in claim 1, wherein; a. essentially vortex-free flow is caused moving the liquid axially downwardly between a pump suction pipe and a surrounding shell and then upwardly to the pump through pipe; b. vortex flow is caused by introducing liquid tangently into the bottom of the shell below the inlet to the pipe.

3. Means for controlling the surface level of a body of liquid which receives an inflow of liquid, comprising; a. a centrifugal pump having a maximum output in excess of the liquid inflow; b. a first means operable to produce an essentially vortex-free flow to the pump, when the surface of the liquid body is above a predetermined level, thereby to produce a maximum output from the pump tending to cause the surface of the liquid to subside; c. a second means operable to produce increasing vortex-flow to the pump, as the surface of the liquid subsides below the predetermined level, thereby to produce a decreasing output from the pump tending to match the inflow of liquid.

4. A controlling means as defined in claim 3, wherein: a. a suction pipe depends from the pump and terminates in an inlet submerged in the body of water; b. the first means is a shell surrounding the suction pipe, having a closed lower end spaced below the suction pipe inlet as well as below the intended lower level of the liquid body and an open upper end below the intended level of the liquid body whereby flow of liquid into the upper end of the shell tends to produce flow of essentially vortex free-liquid to the Suction pipe; c. the second means is at least one tangently disposed inlet near the bottom of the shell tending to produce increasing vortex flow into the suction pipe as the liquid level subsides.

5. A controlling means as defined in claim 4, wherein: a. the inlet end of the suction pipe is spaced above the bottom of the shell a distance approximating the inside diameter of the inlet tube.

6. A controlling means as defined in claim 4, wherein: a. the inside diameter of the suction pipe is larger than the inside diameter of the inlet tube.

7. A controlling means as defined in claim 4, wherein: a. the inlet ends of the suction pipe and inlet tube are flared.