EP0730094A1

EP0730094A1 - Variable level suction device

Info

Publication number: EP0730094A1
Application number: EP96301181A
Authority: EP
Inventors: Timothy John Denmeade; Charles Peter Nyilas
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1995-03-03
Filing date: 1996-02-22
Publication date: 1996-09-04
Anticipated expiration: 2016-02-22
Also published as: DE69607779D1; DE69607779T2; CA2170833A1; EP0730094B1

Abstract

A variable level suction device used in conjunction with a transfer pump which transfers high-level radioactive liquid waste from a waste tank. The variable level suction device comprises an hydraulic housing and a telescoping pipe assembly comprising several pipe sections and mounted alongside the support column of the transfer pump. The telescoping innermost pipe section has a suction inlet, and the outermost telescoping pipe section is welded to the hydraulic housing which encloses an impeller assembly of either a submersible canned motor transfer pump or a lineshaft transfer pump. Suction ports in the hydraulic housing are located adjacent to the impeller assembly. Selective operation of the suction ports and the telescoping pipe sections allows the liquid waste to be suctioned either from the bottom of the waste tank or from a selected level in the waste tank between a free surface and a level near the suction inlet of the innermost pipe section of the telescoping pipe assembly.

Description

This patent application is related to two commonly owned and assigned patent applications entitled "A Submersible Canned Motor Mixed Pump" and "A Submersible Canned Motor Transfer Pump" which are being filed concurrently with this patent application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a submersible pump, and more particularly to a variable level suction device used in conjunction with a submersible transfer pump for pumping high-level radioactive fluid from a selected level in a waste tank.

2. Background of Information

A waste tank is used for the treatment and intermediate storage of high-level radioactive fluids and solutions. The waste is generally aqueous with a high concentration of precipitated solids and a small percentage of organic compounds left over from the radiochemical separations processes. A typical waste tank is mounted in a thick-walled concrete cell in order to shield the environment and persons working in the vicinity of the stored fluids against radiation; is approximately 50 to 60 feet deep; and has a diameter ranging from about 75 to about 85 feet with liquid capacities of approximately one million gallons. A motor mixer pump is used to mix or mobilize the liquid waste or sludge at the bottom of the waste tank and a transfer pump is used to remove the liquid waste from the tank and transfer the liquid waste to another tank for reserve or to a separating process where the liquid is separated from the solid radioactive waste which is vitrified and collected in containers which generally are buried in underground concrete vaults.
Present day transfer pumps have an air cooled motor mounted on a mounting flange at the top of the waste tank and have a fixed length shaft with an impeller assembly suspended vertically from the mounting flange and submerged in the liquid waste.
When the waste is transferred from one waste tank to another waste tank, there may be times when it is desirable to decant only the supernatant fluids. In such cases, the fluid is siphoned off of the top surface which is the free surface, or from the intermediate strata within the waste tank. Presently, this operation involves using present-day transfer pumps each having a different length as that discussed hereinabove, or involves removal of the transfer pump and the installation of a scavenger pump which may be one of two types of vertical turbine pumps. The first type of vertical turbine pump has a long rigid shaft which is designed such that it can be readily raised or lowered from the top of the tank to permit proper adjustment of the position of the impeller in the tank. The second type of vertical turbine pump is known as a flexible floating turbine scavenger pump which has a long rigid shaft which incorporates a flexible suction line with an integral float element which maintains the inlet to the suction line near the free surface of the tank level or relative to the supernatant level for siphoning of the waste therefrom.
This process may involve removing the transfer pump, installing the scavenger pump, and then reinstalling the transfer pump. In order to satisfy the environmental requirements and regulations, these pumps must undergo a decontamination procedure or the pumps must be replaced. The removing, decontaminating, handling, reinstalling or disposing of these transfer and scavenger pumps may run as high as a million dollars in labor support and equipment costs.
Waste management for high radioactive materials is constantly searching for ways in which to simplify the process for transferring both the liquid waste and the supernatant fluid from the waste tank and to do this in such a manner that a single device will satisfy this need.
Ideally, this device would be capable of pumping radioactive fluid from any selected level in a selected range of levels from a free surface to nearly the bottom of a waste tank where the sludge or solid particles settle.
Pumps for handling radioactive or hazardous material are disclosed in U.S. Patent Nos. 4,235,569; 4,389,368; and 4,924,898.
U.S. Patent No. 4,235,569 discloses a typical lineshaft pump for pumping radioactive material and which can operate at a discrete level by coupling the appropriate number of shaft sections together. In this type of pump, the motor is located out of the tank and a fluid displacement impeller, mounted in a housing, is totally immersed in the fluid to be pumped. The impeller is connected to the motor through the shaft coupling system consisting of the several shaft sections. A disadvantage to this pump design is that the fluid or liquid cannot be easily pumped at a desirable level in the waste tank without removing the pump and adding or subtracting the number of shaft sections to provide the required length or providing an additional pump, the results of which include one or more of the several disadvantages associated with the prior art as discussed hereinabove.
A further device of the prior art which includes means for varying the length of a pipe is disclosed in U.S. Patent No. 4,030,859. This device is used to circulate the water in a lake, pond or reservoir, and employs a pair of telescoping pipes beneath a mixing chamber whose upper edge is above the surface of the lake, pond, or reservoir. A major drawback of this device is that it cannot be easily adapted for use with a transfer pump in a waste tank containing high-level radioactive liquid waste.
Thus, there remains a need for a pumping device or arrangement which draws the liquid waste from the bottom of a waste tank containing high-level radioactive material and which draws the fluid from a selected range of levels in the waste tank, thereby greatly enhancing the flexibility of the system and reducing operating downtime and expense.

SUMMARY OF THE INVENTION

The present invention has met the above needs.
The present invention employs a variable level suction device which may be used in conjunction with a transfer pump for pumping radioactive fluids or liquid wastes from a selected level in a selected range of levels from a free surface to nearly the bottom of a waste tank. The apparatus preferably involves an impeller assembly of a transfer pump which is positioned near the bottom of the tank. The variable suction device, preferably, comprises adjustable suction conduit means in the form of a telescoping pipe assembly which comprises several vertical telescoping pipe sections mounted alongside a column assembly of the transfer pump. A suction inlet is in the innermost pipe section, and the outlet is located in the outer most pipe section which is welded to an hydraulic housing. The hydraulic housing preferably encases the housing of an impeller assembly of a lineshaft transfer pump or of a submersible canned motor transfer pump and allows suction to be drawn from suction ports in the hydraulic housing or from the telescoping pipe assembly. Suction ports are located in the hydraulic housing in close proximity to a suction inlet of the impeller assembly. Preferably, the telescoping pipe sections are mounted around a guide rod which in cooperation with the structure of the pipe sections centers the conduit means and provides vertical tracking and alignment of the pipe sections. A drive unit, which, preferably, involves a chain and sprocket device is connected to the innermost pipe section and acts to raise and lower the several telescoping pipe sections relative to the hydraulic housing.
Opening of the suction ports which are located adjacent to the impeller assembly and raising of the telescoping pipe sections such that the inlet of the innermost pipe suction is above the free surface of the fluid allows the liquid waste to be drawn into the impeller assembly from the bottom of the waste tank and up through a discharge conduit for discharge out of the transfer pump. Closing of these suction ports and adjusting the telescoping pipe sections to position the inlet of the innermost pipe section in a selected level of the radioactive fluid, including the free surface, allows the fluid to be drawn from this level in the waste tank.
It is, therefore, an object of the present invention to provide a single, simple means for pumping radioactive fluids from any selected range of levels in a waste tank.
It is a further object of the present invention to provide a means for pumping radioactive liquid waste from the bottom of a waste tank and for pumping the radioactive liquid from the free surface and from intermediate surfaces between the free surface and discrete levels relative to the bottom of the waste tank.
A still further object of the invention is to provide a device which operates in conjunction with a transfer pump for pumping radioactive liquid waste from selected levels in a waste tank, which eliminates the need for additional types of pumps and, thus, reduces the high operating costs typically associated with prior pumping processes.
A further object of the present invention is to provide a simple design for a multi-level pump suction device which is adaptable to any length transfer pump in any size of waste tank.

BRIEF DESCRIPTION OF THE DRAWINGS

A full understanding of the invention can be gained from the following description of the preferred embodiment when read in conjunction with the accompanying drawings in which:

Figure 1 is a cross-sectional view showing the present invention as used with a submersible canned motor transfer pump;
Figure 2 is an enlarged cross-sectional partial view showing in more detail the hydraulic housing of Figure 1 enclosing a lower portion of an impeller assembly of the transfer pump of Figure 1;
Figure 3 is a side elevational partial view of Figure 1 showing in detail the telescoping pipe assembly and the motive means for raising and lowering the telescopic pipe assembly;
Figure 3A is an enlarged cross-sectional view of the portion of the telescoping pipe assembly circled in Figure 3 and labelled "3A";
Figure 4 is a cross-sectional view showing the present invention as used with a lineshaft transfer pump; and
Figure 5 is an enlarged, cross-sectional partial view showing in more detail the hydraulic housing of Figure 4 enclosing a portion of an impeller assembly of the transfer pump of Figure 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to Figure 1, there is shown a submersible canned motor transfer pump 1 which is more fully disclosed in the related patent application entitled "A Submersible Canned Motor Transfer Pump", which patent application is concurrently being filed with this patent application.
Transfer pump 1 is preferably used in a waste tank 3 which is partially shown in Figure 1 and which waste tank 3 is located in the ground. Waste tank 3 contains high-level radioactive liquid waste 5 normally consisting of a fluid and sludge at the bottom of tank 3. The liquid waste may consist of insoluble oxides/hydroxides of aluminum, iron, manganese, and zirconium in water mixtures up to 50% solids by volume. Generally, the liquid waste is first mixed by a mixer pump (not shown) and then drawn out of tank 3 by transfer pump 1.
Transfer pump 1 is comprised of a column assembly 7, motor housing means 9 connected to column assembly 7 and which includes a canned electric motor 11 with radial bearing assemblies 13 and 15 and a thrust bearing assembly 17, and an impeller assembly 18 mounted to motor housing means 9. Impeller assembly 18 is positioned near the bottom 6 of tank 3, and the total length of transfer pump 1 depends on the number and the length of the several pipe sections comprising column assembly 7, as disclosed in the related patent application entitled "A Submersible Canned Motor Transfer Pump".
Electric motor means 11 is the driving means for transfer pump 1, and is comprised of a canned stator assembly and a canned rotor assembly, which prevent the liquid waste from contacting the electrical components of electric motor means 11 and which permit the liquid waste to flow into the annulus formed by the canned stator assembly and the canned rotor assembly to cool the electric motor means 11, as taught in the above related patent application.
Canned motors are well-known in the art and, therefore, further details are not necessary for a full understanding of the present invention.
The stator assembly comprises an outer annular shell 14 and an inner annular stator can 16, both of which are welded to upper and lower annular closure members 19 and 21, respectively. The electrical power supply to electric motor means 11 is supplied to stator assembly by a power cable 23 which extends through upper annular closure member 19.
The rotor assembly comprises a rotor (not shown) in can 25, a shaft 27 extending through and from rotor can 25, journals 29 and 31 connected to the ends of shaft 27, an upper impeller 33 connected on shaft 27, and a lower impeller 35 mounted on the end of shaft 27. The rotor in can 25 may be of the squirrel cage type. Rotor can 25 is welded to shaft 27 to hermetically seal and isolate the components of the rotor from the liquid waste. Upper journal 29 includes the radial bearing assembly 13, and lower journal 31 includes radial bearing assembly 15 and thrust bearing assembly 17. Journals 29 and 31 are, preferably, made of a hard material, such as tungsten carbide, and constitute rotating bearing members 37, 39 with bearing surfaces for radial bearing assemblies 13 and 15, respectively. Radial bearing assemblies 13 and 15 further include a stationary bearing member 41 and 43, respectively, which run against the rotating bearing members 37, 39 of journals 29, 31, respectively on shaft 27, and which bearing members 41, 43 are mounted in annular member 19 and 21, respectively. Static bearing members 41, 43 are preferably made of a hard material, such as tungsten carbide; and undergo a shrink fit process for mounting thereof on annular closure members 19 and 21, respectively.
Trust bearing assembly 17 is located adjacent to lower radial bearing assembly 15. Thrust bearing assembly 17 is comprised of a thrust runner 45, and several thrust shoes, some of which are indicated at numerals 47 and 49. Thrust runner 45 through appropriate means is secured to shaft 27, and has a continuous ring member 51 which run against the thrust shoes 47 and 49. Preferably, the bearing surfaces of bearing assemblies 13, 15, and 17 are made of a hard material, such as tungsten carbide or silicon carbide.
The hard-on-hard radial bearing assemblies 13 and 15 employ axial slots (not shown) in the static bearing members 41 and 43 which allow the large particles of the liquid waste which are greater than the clearances in the system to be ground down into smaller particles and/or to be flushed out by the liquid waste without damage to the components of transfer pump 1.
As best shown in Figure 2, located adjacent to thrust bearing assembly 17 and mounted on rotor shaft 27 is impeller assembly 18 which is comprised of upper impeller 33 and lower impeller 35, a diffuser casing 53 which forms a first and second stage diffusion area with impellers 33 and 35, a suction adapter 55, an inlet screen 57, and support fins 59.
Upper impeller 33 is a second stage impeller and is keyed to shaft 27 to prevent rotation relative to shaft 27. Upper impeller 33 is greater in diameter than lower impeller 35, and its diameter is such that it accounts for the hydraulic losses associated with the dumped diffusion casing 53 and a vertical discharge pipe assembly (not shown).
Lower impeller 35 is keyed to shaft 27 to prevent relative rotation therebetween, and is spaced axially from upper impeller 33. The upper shroud of lower impeller 35 is located less than six inches from the inlet of suction adaptor suction adapter 55 of impeller assembly 18. This insures that transfer pump 1 is able to empty tank 3 to below a six inch liquid waste level in tank 3 since it is necessary for the impeller 35 to be completely covered by the liquid waste in order for the impeller assembly 18 to be able to pump the liquid waste 5.
Fins 59 are bolted to suction adapter 55 and act as guides for transfer pump 1 when transfer pump 1 is installed into tank 3, and act to reduce the vortexing of the liquid waste 5 when transfer pump 1 is operated at low liquid waste levels. That is, at low levels, the liquid waste 3 tends to swirl, and fins 59 counteract the whirlpool or swirling effect.
Impeller assembly 18 has two stages where the first staged diffusion area has several vanes, which in cooperation with casing 53 turn the flow of the liquid waste from the lower impeller 35 into the upper impeller 33 which with casing 53 acts as a second stage dumped diffusion area, from which area, the liquid waste flows up into several discharge pipes of a discharge assembly (not shown).
The impeller assembly 18 draws liquid waste into suction adapter 55 through the first stage diffusion area of lower impeller 35 and into the second stage diffusion area of upper impeller 33, where most of the liquid waste is taken up through the several vertical discharge pipes of the discharge assembly (not shown). However, some of the liquid waste is forced upwardly through thrust and radial bearing assemblies 17 and 15, respectively, and through the annulus formed by the stator can 16 and rotor can 25, wherein the large particles are reduced in size by the bearing members of bearing assemblies 15 and 17, and wherein the liquid waste cools electric motor means 11 and cools and/or lubricates bearing assemblies 13, 15, and 17.
The discharge assembly (not shown) communicates with several cylinder sections 61 and 63 of column assembly 7 shown in Figure 1, which cylinder sections 61 and 63 each have a central conduit for receiving and carrying the liquid waste out of transfer pump 1.
Figures 1, 2, 3, and 3A show a variable level suction device 65 which essentially is an adjustable suction conduit means and which encompasses the present invention.
Referring particularly to Figure 2, variable level suction device 65 comprises an hydraulic housing 67 essentially encasing the lower portion of impeller assembly 18 including lower impeller 35, and a telescoping pipe assembly 69 which essentially is a suction conduit means. Hydraulic housing 67 contains a suction chamber 71 and suction ports 73. Hydraulic housing 67 forms chamber 71 around lower impeller 35 from which chamber 71, impeller 35 draws its pumped liquid waste, and which hydraulic housing 67 allows suction to be drawn from either the bottom of tank 3 through suction ports 73 or from telescoping pipe assembly 69.
Referring particularly to Figure 1, telescoping pipe assembly 69 consists of several vertical pipe sections 75, 77, 79, and 81. An innermost pipe section 75 has an inlet 83, and the outermost pipe section 81 is welded to hydraulic housing 67 and has an outlet 84, which is in flow communication with the suction chamber 71 formed in hydraulic housing 67.
Telescoping pipe assembly 69 is mounted alongside column assembly 7 and motor housing means 9 of transfer pump 1, and is vertically adjustable via a chain and sprocket assembly 85 (Figure 3) which is driven by a motor 87 (Figure 1) mounted on a mounting flange 89, which flange 89 supports and suspends the several devices used in waste tank 3, including transfer pump 1 in a manner well-known in the art. As is shown in Figure 1, flange 89 also supports electrical connection means 91 for electrical cable 23 and the discharge pipe 61 of column assembly 7.
As shown in Figure 3, a chain 93 is connected to innermost pipe section 75 by way of a bracket 95 which encircles and is welded to the upper outer surface of pipe section 75. Chain 93 is driven around a sprocket 94 connected to outer pipe section 81 and is driven by motor 87 shown in Figure 1. Operation of chain and sprocket assembly 85 expands and retracts pipe assembly 69.
Pipe sections 75, 77, 79, and 81 from the outermost pipe section 81 to the innermost pipe section 75 have decreasing diameters so that pipe sections 75-81, when in a compressed and uncompressed state, fit within each other. The inner end of each pipe section 75, 77, and 79 have a flange and the outer end of each pipe section 77, 79, and 81 have a flange which overlap and cooperate with the flange of pipe sections 75, 77, and 79 to retain pipe sections 75, 77, and 79 within each other when pipe assembly 69 is being expanded vertically upwardly in tank 1 of Figure 1. Figure 3A shows an example of this relationship where an outer flange 78 of pipe section 77 overlaps inner flange 76 of pipe section 75. The diameters or bores of pipe sections 75-81 are relatively small, for example about 2-1/2 to 4 inches, and therefore have close tolerances between each cooperating adjacent pipe section which minimizes leakage through the joints of pipe assembly 69 and which feature, in part, makes the pipe assembly 69 flexible enough to accommodate vast movements of the column assembly 7. Pipe sections 75-81 are concentrically assembled over a guide rod 97. Still referring to Figure 3A, the inner flange 76 of pipe section 75 has a radial rib 80 which is slightly spaced away from guide rod 97. Several of these radial ribs 80 are spaced around flange 76 in a manner similar to that shown in Figure 3A. These radial ribs 80 are provided on the inner flange of pipe sections 75, 77, and 79, and cooperate with guide rod 97 to center pipe assembly 69 and to provide vertical tracking and alignment for bracket 95 and chain 93 in raising and lowering pipe sections 75, 77, and 79 in a telescoping fashion relative to fixed pipe section 81. These radial ribs in each pipe section 75, 77, and 79 are spaced around its respective inner flange such as to provide flow areas in the bores of pipe sections 75, 77, 79, and 81.
From the above, it is appreciated that pipe sections 75, 77, and 79 are extended and retracted within pipe section 81 through operation of chain and sprocket assembly 85 of Figure 3. When being extended, the flange 76 of the inner end of innermost pipe section 75 engages the flange 78 on the outer end of pipe section 77. Further upward movement of chain 93 causes pipe section 77 and 79 to be raised in a similar manner. This process can be continued until all pipe sections 75, 77, and 79 are raised out of fixed pipe 81, while motor 87 holds chain 93 in this fixed position. As is apparent, chain 93 is operated to expand or retract the pipe sections 75, 77, and 79 and then held in a desired position for obtaining a fixed length for pipe assembly 69, depending on the level in tank 3 in which liquid waste 5 is to be drawn into inlet 83 of pipe section 75. Referring again to Figure 1, motor 87 operates chain and sprocket assembly 85 to progressively raise and lower pipe sections 75, 77, and 79 in and out of fixed pipe section 81 within a range of liquid waste levels in waste tank 3. This range level may be defined as being from a top surface 4, which is commonly referred to as a "free surface" to a bottom surface which may be a couple of feet from the bottom 6 of waste tank 3, depending on the minimum length of telescoping pipe assembly 69 in a compressed state. Impeller assembly 18 must be positioned at least approximately six inches from the bottom of waste tank 3 in order for transfer pump 1 to be effectively operated, and pipe sections 75, 77, and 79 are articulated from a compressed state in pipe section 81 to any elevation starting from the top end of the compressed state up to or above the free surface 4 in tank 3. Even though a chain and sprocket assembly 85 is discussed herein, it will be appreciated that other suitable motive means may be used, such as an hydraulic piston cylinder assembly.
As shown particularly in Figure 2 and as discussed hereinabove, hydraulic housing 67 has suction ports 73, which are located in the lower portion of hydraulic housing 67 and near to the inlet to suction adapter 55 of impeller assembly 18. Suction ports 73 each have a gate 99 which is slidably operated in hydraulic housing 67 through an activator rod 101 welded to gate 99. Actuator rods 101 are interconnected and, are, in turn, connected to an actuator rod 102. Actuator rod 102, as shown in Figure 1, extends vertically alongside column assembly 7 and is operated by a worm-gear 103 driven by motor 105. Each gate 99 is guided in its vertical movement by an angle member 107 which is welded inside hydraulic housing 67.
With particular reference to Figure 1, if liquid waste is to be drawn from the bottom of waste tank 3, assuming impeller assembly 18 is located near the bottom 6 of tank 3, suction ports 73 are opened and telescoping pipe assembly 69 is raised until the inlet 83 in pipe section 75 is above the free surface 4 in waste tank 3 of Figure 1. This creates a suction path from suction ports 73 to suction adapter 55 of the impeller assembly 18, and the liquid waste 3 is drawn up into impeller assembly 18 and through the discharge conduit in pipe sections 61 and 63 of column assembly 7 and out of waste tank 3.
Liquid waste can be drawn from the free surface or from any level between the free surface down to a level where telescoping pipe assembly 69 is in a compressed state and where inlet 83 of pipe section 75 is still able to operate to suction liquid waste sufficiently into hydraulic housing 67. In this case, pipe section 75 is raised or lowered in the desired level, and suction ports 73 in hydraulic housing 67 are closed in order to obtain a closed loop between the suction area of inlet 83 of pipe section 75 and the discharge area through transfer pump 1. The liquid waste 5 is drawn up into pipe assembly 69, into hydraulic housing 67, into impeller assembly 18, and out through column assembly 7. During shutdown operations and all pump operating conditions of transfer pump 1 where the suction inlet 83 of innermost pipe section 75 of telescoping pipe assembly 69 is submerged in the liquid waste 5 of waste tank 3, the level of waste 5 in tank 3 is the same as the level of waste 5 in suction inlet 83. When transfer pump 1 is operating and suction ports 73 in hydraulic housing 67 are closed, transfer pump 1 takes suction from the hydraulic housing 67, which is in communication with suction inlet 83 of telescoping pipe assembly 69.
The developed suction pressure inside hydraulic housing 67 from where pump 1 takes its suction is insignificantly affected, whether pump 1 takes suction through ports 73 in hydraulic housing 67 or through suction inlet 83 of telescoping pipe assembly 69. That is, there is a difference in the pressures when pump 1 is drawing from suction inlet 83 of telescoping pipe assembly 69 and suction ports 73 are closed as compared to when pump 1 is drawing from suction ports 73 and suction inlet 83 of pipe assembly 69 is out of the waste 5 in tank 3. This is attributed to the pressure drop in pipe assembly 69 when pump 1 is drawing waste 5 from above hydraulic housing 67 and ports 73 are closed. However, this pressure drop is minimal; is at its maximum at the longest extension of telescoping pipe assembly 69; and has the least effect on the suction pressure since the static pressure contribution at pump suction increases with the elevation of telescoping pipe assembly 69 in waste tank 3.
The velocity of the liquid waste 5 in pipe assembly 69 is relatively low; for example, less than 5 feet per second, causing the maximum hydraulic loss in pipe assembly 69 to occur when suction inlet 83 is positioned at or near the top or free surface 4 of waste 5 in tank 3. This hydraulic loss is minimal. For example, a 30 foot column of liquid waste 5 in pipe assembly 69 (a hydrostatic pressure of approximately 11 psi) produces less than 1 psi drop in suction pressure in hydraulic housing 67. As the level of waste 5 in tank 3 and the submerged suction inlet 83 are lowered, the pressure losses in pipe assembly 69 diminish and remain relatively small compared to the magnitude of the hydrostatic pressure in hydraulic housing 67.
When transfer pump 1 draws suction through ports 73, the recommended position for suction inlet 83 in pipe assembly 69 is above the free surface 4 in waste tank 3. This assures that pump 1 is drawing suction solely from ports 73. Otherwise, some fraction of suction may be drawn from suction inlet 83. In the raised position of suction inlet 83 out of liquid waste 5, some small amount of suction will be drawn through the gaps formed between each pipe section 75, 77, 79 and 81 relative to each other, however, this amount of suction is relatively small (less than 1%) compared to the main flow of suction through suction ports 73.
As particularly shown in Figure 2, the bottom wall 68 of hydraulic housing 67 is in an inverted "V" configuration which aids in directing the flow of waste 5 into impeller assembly 18.
The lowest suction level for telescoping pipe assembly 69 is limited by the length of the lowest pipe section 81. In general, the lowest suction level for pipe assembly 69 will be a few feet, for example, approximately 3 to 4 feet, above the bottom 4 of tank 3. The lowest suction level for drawing in waste 5 through suction ports 73 in hydraulic housing 67 will be greater than six inches from bottom 4 of tank 3 since impeller assembly 18 should be at least six inches from the bottom in waste 5 in order for pump 1 to function properly.
Figures 4 and 5 illustrates the variable level suction device 69 of the present invention as being used in conjunction with a lineshaft type of transfer pump 111. Device 69 is similar to that of Figures 1-3A, and therefore like numerals designate like components. Transfer pump 111 comprises an electric motor means 113, a column assembly 115, through which a lineshaft 117 extends, and an impeller assembly 119 electrically connected to motor means 113 through lineshaft 117.
As is shown in Figure 4, motor means 113 is mounted on a mounting flange 121 out of and on top of a waste tank 123, where it is air cooled. Column assembly 115 extends into waste tank 123 to position impeller assembly 119 in the liquid waste 125 of waste tank 123. As with the column assembly 7 of transfer pump 1 of Figure 1, the number of pipe segments of column assembly 115 can be selected in order to obtain a desirable fixed length for transfer pump 111 of Figure 4.
When using the device 69 of the present invention, preferably, this fixed length will position impeller assembly close to tank floor 6 for drawing liquid waste from this area while device 69 is operated to draw in liquid waste from an area above hydraulic housing 67 in the manner described hereinabove with regard to device 69 for the transfer pump 1 of Figures 1-3A.
Hydraulic housing 67 encases impeller assembly 119 which is in flow communication with the discharge conduit means extending through column assembly 115, in a manner well-known in the art.
In this embodiment of Figures 4 and 5, variable level suction device 69 is operated in a manner similar to that described hereinabove with reference to Figures 1-3A for the submersible canned motor transfer pump, whereby the liquid waste is drawn through impeller assembly 119 and directly up into and through column assembly 115 of transfer pump 111.
It will also be appreciated that the variable level suction device 69 of the present invention can be used with any type of pump for drawing liquids or fluids out of a container.
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.

Claims

Apparatus for pumping fluid from a selected level in a selected range of levels from a free surface to a bottom of a container (3), said apparatus comprising:
submerged pump means (1) positioned adjacent said bottom of said container;

adjustable suction conduit means (65) having inlet means and outlet means (84), said outlet means being in communication with said submerged pump means;

positioning means (85)connected to said adjustable suction conduit means to adjustably position said inlet means to said selected level of said fluid in said container; and

a discharge conduit (61) extending from said submerged pump means out of said fluid,

said submerged pump means drawing said fluid at said selected level in said selected range through said inlet means of said adjustable suction conduit means for discharge of said fluid through said discharge conduit of said submerged pump means.
The apparatus of Claim 1 wherein said discharge conduit is suspended from above said container and extends downward toward said bottom, and supports said submerged pump means adjacent said bottom of said container.
The apparatus of Claim 2 wherein said adjustable suction conduit means is extendable and retractable by said positioning means.
The apparatus of Claim 3 wherein said adjustable suction conduit means comprises a telescoping pipe assembly (69) having a plurality of telescoping pipe sections (75, 77, 79 and 81), an inner one of which has said inlet means and an outer one of which has said outlet means, and wherein said positioning means comprises means (85) for extending and retracting said telescoping pipe sections to adjustably position said inlet means at said selected level of said fluid.
The apparatus of Claim 4 wherein said positioning means further includes guide means (78, 76) guiding said telescoping pipe sections along a substantially vertical path.
The apparatus of Claim 5 wherein said guide means comprises a substantially vertical rod (97) around which said telescoping pipe sections are mounted.
The apparatus of Claim 6 wherein said means for extending and retracting said telescoping pipe sections comprises motive means (113) mounted above said free surface and drive means (117) connected to said motive means and to at least one telescoping pipe section.
The apparatus of Claim 7 wherein said drive means comprises a flexible member guided in a loop by said motive means and an idler near said submerged pump means and connected to said at least one telescoping pipe section.
The apparatus of Claim 6 wherein said submerged pump means further comprises impeller means and motor means connected to said impeller means for driving said impeller means, and
wherein said adjustable suction conduit means further comprises:

hydraulic housing means (67) in flow communication with said outlet means (84) of said outer one of said pipe sections of said telescoping pipe assembly, and having a suction chamber and encasing said impeller means of said submerged pump means,

suction port means in said hydraulic housing means adjacent to said impeller means, and

means for selectively opening and closing said suction port means and

wherein said outlet means of said adjustable suction conduit means is structured to communicate with said suction chamber above said suction port means of said hydraulic housing means.
The apparatus of Claim 9 wherein said means for selectively opening and closing said suction port means comprises:
slidable gate means;

actuator rod means connected to said slidable gate means; and

drive means mounted above said free surface for operating said actuator rod means and for vertically sliding said slidable gate means.
The apparatus of Claim 1 wherein said submerged pump means is a submersible canned motor transfer pump; wherein said fluid is radioactive waste, and, wherein said container is a waste tank.
The apparatus of Claim 1 wherein said submerged pump means is a lineshaft transfer pump; wherein said fluid is radioactive waste and; wherein said container is a waste tank.
The apparatus of Claim 1 wherein said adjustable conduit means comprises a plurality of telescoping pipe sections.
The apparatus of Claim 13 wherein said positioning means includes guide means guiding said telescoping pipe sections in a substantially vertical path.
The apparatus of Claim 14 wherein said guide means comprises a substantially vertical rod around which said telescoping pipe sections are vertically slidable.
The apparatus of Claim 15 wherein said positioning means includes chain drive means for vertically sliding said telescoping pipe sections along said substantially vertical rod.