US3743444A - Oil-diaphragm slurry pump - Google Patents

Abstract

The oil-diaphragm chamber of an oil-diaphragm slurry pump is provided with level detection sensors for detecting the oil diaphragm position and an air detection sensor for detecting air quantity in the chamber, and an automatic controller operates in response to detection signals from these detection sensors to operate oil-supplying and oil-discharging valves and thereby to control and maintain the oil diaphragm at a predetermined normal position and to discharge accumulated air from the chamber.

Description

United States Patent [1 1 Kazama et al.

[451 July 3, 1973 OIL-DIAPHRAGM SLURRY PUMP [75] Inventors: Toshlo Kazama; Kazunorl Seki, both l' Exqm'rfer ca.rlton Crqye of Nagaoka, Japan Assistant Exammer-Richard E. Gllck Attorney-Robert E. Bums et al. [73] Assignee: Tamagawa Klkal Klnzoku Kabushlkl Kaisha, Tokyo-to, Japan [22] Filed: Jan. 26, 1972 21 Appl. No.2 220,775 [571 ABSTRACT [30] Foreign Application Priority Data The oil-diaphragm chamber of an oil-diaphragm slurry J 24 1971 J 46 45971 pump is provided with level detection sensors for deune apan tecting the oil diaphragm position and an air detection sensor for detecting air quantity in the chamber, and an [52] 417/92 417/385 47 automatic controller Operates in response to detection signals from these detection sensors to operate oil- 2; 'g' L" 11/00 3 supplying and oil-discharging valves and thereby to Z 7 g g H04 9 control and maintain the oil diaphragm at a predeter- 206 mined normal position and to discharge accumulated air from the chamber.

[56] References Cited 7 UNITED STATES PATENTS 2 Claims, 1 Drawing Figure 1,342,798 6/1920 Farrand 417/99 2o QCONTROLLER/ 200 7 20b IO 1 19 4 B I A s 't u... 7 K r (I'll/Ida Q 5 t i s '6 4,,,, ,w//7,2 .e=-... r 8 t, v a A 6 J R PMENTEB 1"- 3W5 CONTROLLER OIL-DIAPHRAGM SLURRY PUMP BACKGROUND OF THE INVENTION This invention relates generally to liquid-diaphragm type pumps and more particularly to slurry pumps of the oil-diaphragm type for deliverying under pressure liquids containing abrasive particlessuch as slurries of ores. More specifically, the invention relates to a new and advanced system for automatically adjusting the oil-slurry interface and for automatic deaeration in slurry pumps of the above stated class.

In slurry pumps of the piston type and the plunger type, the slurry flows directly into the interiors of the cylinders, whereby the cylinder interiors and other parts are subjected to rapid wear and, therefore, cannot withstand operation over a long time.

As one solution to this problem, liquid-diaphragm type slurry pumps having been developed and are at present being widely used. A slurry pump of this type comprises, essentially, a reciprocating pump for-applying reciprocating motion to a liquid (e.g., an oil) of a specific gravity less than that of the slurry to be pumped, a valve box containing slurry suction and delivery valves, and a vertical oil-diaphragm chamber connected at its upper part via an oil connecting pipe to the cylinder of the reciprocating pump and at its lower part via a slurry connecting pipe to a part of the valve box between the suction and delivery valves.

The lower part of the oil-diaphragm chamber and the slurry connecting pipe are filled with slurry, while the upper part of the diaphragm chamber above the slurry, the oil connecting pipe, and the cylinder of the reciprocating pump are filled with the oil. The difference between the specific gravities of the slurry and the oil maintains the oil above the slurry in the oil diaphragm chamber with an interface between the two liquids. Thus, reciprocating or pulsating motion is' applied to the slurry while the slurry is prevented from infiltrating into the pump cylinder.

Slurry pumps of this type are described in the specifications of Japanese Patent Publication No. l2l3l/l960, U.S. Pat. No. 3,241,496, patented Mar. 22, 1966, British Pat. No. l,l87,9l2, patented Aug. 20, 1970, and South African Patent No. 68/0752, patented May 30, 1969.

Since there is no wearof the'pump cylinder and piston or plunger by the slurry in a slurry pump of this liquid-diaphragm type, the slurry pump is capable of operating with high efficiency in delivering slurry under pressure. In this operation, however, it is necessary to hold the interface between the oil and the slurry in the oil-diaphragm chamber continually at a correct posito discharge the accumulated air. For these reasons, it

has been necessary heretofore to station one or more operational personnel in the pump area at all times.

SUMMARY OF THE INVENTION at the pump and, at the same time, eliminate malfunction. Heretofore, in order to maintain this interface it has been the practice heretofore for the operator to make periodic checks and to open a deaerating valve tioning and trouble arising from lack of operator manpower, the ultimate object being to reduce operational costs.

According to this invention, briefly summarized, there is provided an automatic control system for automatically and controllably maintaining the oil diaphragm and extracting air in the oiLdiaphragm chamber of an oil-diaphragm type slurry pump, the control system comprising a level detection device for detecting the position of the oil diaphragm, an air detection device for detecting air quantity within the chamber, oil-supplying and oil-discharging valves, and an automatic controller for operating in response to detection signals from the level detection andair detection devices to operate the oil-supplying and oil-discharging valves and thereby to maintain the oil diaphragm at a predetermined normal position and to discharge air from the chamber.

The nature, principle, utility, and further features of this invention will be apparent from the following detailed description with respect to a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawing, the single FIGURE is a diagrammatic side elevation, in vertical section, showing the essential parts of an oil-diaphragm type slurry pump incorporating an example of the automatic control system according to this invention.

DETAILED DESCRIPTION As described briefly hereinabove, an oil-diaphragm type slurry pump comprises, essentially, a pump device A, a valve box device B, and an oil-diaphragm chamber device C connected therebetween.

The pumpdevice A comprises a plunger pump driving mechanism 1, a plunger 2, and a cylinder 3 in which the plunger 2 operates. The valve box device B comprises a valve box 4, upper (delivery) and lower (suction) valve seats 5 and 6 provided within the valve box, ball valves 7 and 8 for cooperative operation with valve seats 5 and 6, respectively, a slurry suction pipe 9, and a slurry delivery pipe 10. The oil-diaphragm chamber device C comprises a vertical chamber 11, an oil connecting pipe 11 communicatively connecting the upper connecting pipe [3 connecting the lower part of the a chamber to a part between the two valve seats 5 and 6 of the valve box 41, an oil tank 15 disposed above the chamber and connected to the upper part thereof by way of an oil supply valve 14.

By opening the valve 14 to introduce oil 0 from the tank 15 into the upper part of the chamber 11, the oil connecting pipe 12, and the pump cylinder 3, and introducing slurry S into the lower part of the valve box 4, the slurry connecting pipe 13 and the lower part of the chamber 11, an interface L is formed naturally between the oil 0 and the slurry S in the chamber 11 be- More specifically, when the drivingmechanism 1 operates to drive the plunger 2 in its compression stroke toward the left, as viewed in the drawing, the oil in the cylinder 3 is displaced into the diaphragm chamber 11, whereby the interface L is forced downward to apply pressure on the liquid column of the slurry S. This applied pressure is transmitted through the slurry connecting pipe 13 to the slurry between the upper (delivcry) and lower (suction) ball valves 7 and 8 in valve box 4. Consequently, the suction valve 8 is closed, and the delivery valve 7 is raised and opened, whereupon a volume of slurry substantially equal to that of the slurry displaced downward in the diaphragm chamber 11 is discharged into the delivery pipe 10.

During the return stroke of the plunger 2, negative pressure is imparted to the oil 0, which is thereby drawn into the cylinder 3, whereby the interface L is raised to transmit the negative pressure by way of the slurry S in the diaphragm chamber 11 and the slurry in the connecting pipe 13 to the slurry between the valves 7 and 8 in the valve box 4. Consequently, the delivery valve 7 is closed, and the suction valve 8 is opened to permit slurry to be drawn from the suction pipe 9 toward the chamber 11 through the connecting pipe 13.

Thus, the reciprocating motion of the plunger 2 produces a pumping action whereby slurry is drawn from the suction pipe 9 and discharged into the delivery pipe 10.

The aforestated object is achieved in accordance with this invention by providing, in a slurry pump of the above described organization and operation, a control system as described below for automatically controlling the level of the oil-slurry interface L and removing accumulated air in the oil-diaphragm chamber 11.

In the example of this control system as illustrated in the drawing, four sensors 16, 17, 18, and 19 are installed through and supported by the side wall of the diaphragm chamber 11 at respectively specific heights. The lowest sensor 16 is adapted to detect the interface L at its lower limit of fluctuation and is installed at the height position of lowest limit of the interface required for operation. The sensor 17 is adapted to detect the interface L at its set medial position and is installed at the desired normal medial position. The sensor 18 is adapted to detect the interface at its upper limit of fluctuation and isinstalled at the height position of highest limit of the interface'necessary for operation. The highest sensor 19 is adapted to detect the presence of air and is installed in the vicinity of the highest part of the interior of the chamber 11.

All of these sensors are connected to a controller 20 to send respective detection signals thereto. The controller 20 contains four controller elements 20a, 20b, 20c and 20d which are connected to the sensors 16, l7, l8, and 19, respectively. Each of these controller elements is, for example, a switching element which, upon receiving the detection signal from the associated level sensor, sends an operating signal to valve actuators 14a and/or 22a for the valves 14 and 22 to open or close the same. As mentioned hereinabove, the valve 14 is an oil supply valve installed in an oil supply line from the oil tank 15 to the upper part of the diaphragm chamber 1 1. The valve 22 is installed in an oil return line 21 provided as a part of the system from the upper part of the chamber 11 to the upper part of the oil tank 15. The oil return line 21 and the oil supply line in which the valve 14 is installed are provided with respective means such as check valves (not shown) to prevent flow of oil therethrough-in directions reverse to those intended (as indicated by arrows). 4

The control system of this invention of the essential organization as describe above operates in the following manner during the operation of the slurry pump as described hereinbefore. First, prior to the slurry pump operation, the supply of oil into the diaphragm chamber 11 is so adjusted that the medial position of the interface L is at the level of the sensor 17. The pump driving mechanism is then started to start normal operation of the slurry pump as described hereinbefore.

However, as the slurry pump is operated over a long period, the level of the interface L gradually moves upward because of occurrences such as wetting of packings and leakage of the oil which cause a decrease in the oil quantity in the chamber 11 and thereby a disturbance of the initial balance between the slurry S and the oil 0.

When the interface level continues to rise and reaches the level of the sensor 18 for detecting the upper limit, the sensor 18 detects this condition and automatically sends a corresponding signal to the controller 20. The controller 20 thereupon operates automatically to generate and send an output to operate the oil supply valve 14 in the direction for opening the same. Consequently, oil is supplied from the tank 15 to the interior of the chamber 1 1, whereby the level of the interface L descends.

When the interface reaches the level of the sensor 17 (i.e., the set medial position), the sensor 17 detects this condition and sends a corresponding signal to the controller 20, which thereupon operates to produce an output which closes the oil supply valve 14. Thus, the interface is automatically adjusted at the predetermined normal medial position.

When, for some reason, the interface L descends and reaches the level of the sensor 16, the sensor 16 detects this condition and operates to send a corresponding signal to the controller 20.The controller 20 thereupon operates in response to this detection signal to produce an output for opening the valve 22, whereby some of the oil in the chamber 11 is returned'to the oil tank 15 .through the line 21 by the compressing action of. the

plunger 2. As a result, the interface level rises, and when it reaches the level of the sensor 17, the sensor 17 sends a signal to the controller 20, which thereupon operates to close the valve 22. Thus, the normal level of the interface L is automatically adjusted to the set normal position.

In this manner whenever the position of the interface L deviates from the correct nonnal position for some reason and reaches a level outside of the range of movement thereof necessary for operation, this condition is detected by either of the sensors 16 and 18, and the detection signal is. sent to the controller 20, whereby the appropriate valve for supplying or discharging oil is automatically opened and then closed,

and the interface is thereby automatically adjusted to its normal position.

Furthermore, when air collects in the diaphragm chamber 11 to reach the set position of the air sensor 19, the air sensor 19 detects this condition and sends a detection signal to the controller 20. The controller 20. operates in response to this signal to open the valve 22 for a short time, whereupon the accumulated air is discharged through the line 21 to the atmosphere.

We claim:

1. In a slurry pump of oil-diaphragm type having an oil-diaphragm chamber in which an oil-slurry interface constituting an oil diaphragm is formed, an automatic control system comprising level detection means for detecting the position of the oil diaphragm, air detection means for detecting air quantity within the chamber, oil-supplying and oil-discharging valves, said valves communicating with said chamber and said oil supplying valve communicating with a source of oil,

and an automatic controller for operating in response to dection signals from the level detection means and the air detection means to operate said valves and thereby to maintain the oil diaphragm at a predetermined normal position and to discharge air from the chamber.

2. In a slurry pump according to claim 1: wherein said level detection means comprises a high limit level sensor, a low-limit level sensor and a normal-level sensor; and wherein said controller is operative to open said oil supplying valve to supply oil into said chamber upon receiving a detection signal from the high-limit level sensor, to open said oil-discharging valve to discharge oil from within said chamber upon receiving a detection signal from the low-limit level sensor, and to close said valves upon receiving a detection signal from the normal level.

Claims (2)

1. In a slurry pump of oil-diaphragm type having an oildiaphragm chamber in which an oil-slurry interface constituting an oil diaphragm is formed, an automatic control system comprising level detection means for detecting the position of the oil diaphragm, air detection means for detecting air quantity within the chamber, oil-supplying and oil-discharging valves, said valves communicating with said chamber and said oil supplying valve communicating with a source of oil, and an automatic controller for operating in response to dection signals from the level detection means and the air detection means to operate said valves and thereby to maintain the oil diaphragm at a predetermined normal position and to discharge air from the chamber.

2. In a slurry pump according to cLaim 1: wherein said level detection means comprises a high limit level sensor, a low-limit level sensor and a normal-level sensor; and wherein said controller is operative to open said oil supplying valve to supply oil into said chamber upon receiving a detection signal from the high-limit level sensor, to open said oil-discharging valve to discharge oil from within said chamber upon receiving a detection signal from the low-limit level sensor, and to close said valves upon receiving a detection signal from the normal level.

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