Field of the Invention

This invention relates to fluid pumps and also monitoring systems for fluid pumps.

The invention has been devised particularly, although not necessarily solely, for centrifugal pumps.

Background Art

The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.

Centrifugal pumps are often used to pump slurries along flow lines in slurry processing operations. If the slurry flow rate falls below its settling velocity, the solids settle in the flow line, causing a blockage. Operation of a centrifugal pump with a blocked suction line or a blocked discharge line is most undesirable. With such a blockage, slurry may cease to flow, or at least being adversely retarded in its flow, through the pump, resulting in a remnant volume of the slurry being confined within the pump. The impeller of the centrifugal pump, however, continues to rotate and so spins in the confined volume f slurry within the pump. This action generates heat within the confined slurry, which can raise the pressure within the pump casing if sufficient heat cannot be dissipated by the pump. In certain instances, liquid within the slurry can turn into superheated steam. If the resulting pressure cannot be dissipated prior to casing failure, the pump may explode. Fatalities have been recorded when people have been in close proximity to the pumps operating under such conditions. The greater use of mechanical seals and variable speed drives on slurry pump equipment has further increased the risk of explosion.

Before the use of mechanical seals to reduce shaft leakage, most pumps were fitted with gland packing. Although it was possible for pumps containing gland packing as the shaft seal to explode, the packing often 'blew out' before the casing exploded.

Variable speed drives are now commonly used to optimise the transfer of slurry, pumping it at just above the settling velocity, which is usually the most efficient way of transferring the solids: If a variable speed drive slows to a point where the pump no longer creates the fluid velocity to prevent the solids settling in the flow line, the risk of explosion is greatly increased.

There have been various proposals to mechanically dissipate the pressure prior to risk of explosion. Such proposals, including pressure relief valves, bursting disks, and melting rings, have not proved to be cost-effective and can be difficult to maintain.

It is against this background, and the problems and difficulties associated therewith, that the present invention has been developed.

Disclosure of the Invention According to a first aspect of the invention there is provided a pump for processing a fluid comprising a body defining a suction inlet and a discharge outlet, and means responsive to a prescribed temperature condition associated with the pump.

- Preferably, the fluid comprises slurry. Preferably, the temperature condition is the temperature of the fluid being processed by the pump.

In another arrangement, the temperature condition is the temperature of at least one component of the pump.

Preferably, the temperature is the temperature of the fluid located within the pump between the suction inlet and the discharge outlet of the pump.

Preferably, the pump comprises a pump casing.

Preferably, the means responsive to a prescribed temperature condition are mounted on the pump casing. Preferably, the pump casing is adapted to receive a casing liner. Preferably, the casing liner is a replaceable casing liner.

Preferably, the means responsive to a prescribed temperature condition are mounted on the pump casing liner. Preferably, the means responsive to a prescribed temperature condition is in heat exchange relation with the pump casing liner.

Preferably, the means responsive to a prescribed temperature condition comprise a temperature sensor.

Preferably, the temperature sensor comprises a temperature measuring device. Preferably, the temperature measuring device comprises a resistance temperature detector.

Preferably, the temperature sensor is adapted to operate an indication system. Preferably, the indication system comprises an alarm.

Preferably, the temperature sensor is adapted to interrupt operation of the pump. Preferably, the pump comprises a centrifugal pump.

Preferably, the body comprises a pump casing defining a volute chamber and an impellor accommodated in the volute chamber.

Preferably, the means responsive to a prescribed temperature condition are mounted on the volute chamber. Preferably, the pump further comprises a throat bush.

Preferably, the means r sponsive to a prescribed temperature condition are mounted on the throat bush.

Preferably, the prescribed temperature condition associated with the pump comprises an abnormal operating temperature for the pump. Preferably, the abnormal operating temperature for the pump comprises a temperature at which operation of the pump is approaching undesirable state.

Preferably, the abnormal operating temperature for the pump is indicative of obstructed fluid flow. According to a second aspect of the invention there is provided a system for monitoring the operation of a pump which comprises a body having a suction inlet and a discharge outlet, the monitoring system comprising a means responsive to a prescribed temperature condition associated with the pump, said means being operable to initiate action in relation to operation of the pump. Preferably, the action comprises actuation of an indication system and/or interruption of the operation of the pump.

Preferably, the indication system comprises an alarm.

Preferably, the temperature condition associated with the pump is indicative of obstructed fluid flow through the pump. According to a third aspect of the invention there is provided a method of pumping a fluid comprising the steps of operating a pump to pump the fluid and monitoring the operation of the pump to detect a prescribed temperature condition associated with the pump.

Preferably, the prescribed temperature condition associated with the pump comprises an abnormal operating temperature for the pump.

Preferably, the abnormal operating temperature for the pump comprises a temperature at which operation of the pump is approaching undesirable state.

Preferably, the abnormal operating temperature for the pump is indicative of obstructed fluid flow. Brief Description of the Drawings

The invention will be better understood by reference to the following description of one specific embodiment thereof, as shown in the accompanying drawings in which: Figure 1 is a schematic side view of a pump according to the embodiment;

Figure 2 is a fragmentary view, on an enlarged scale, of the pump;

Figure 3 is a front view of a frame plate liner insert forming part of the pump; and

Figure 4 is a cross-sectional view on line 4-4 of Figure 3. Best Mode(s) for Carrying Out the Invention

The embodiment shown in the drawings is directed to a centrifugal pump 10 intended particularly for applications involving slurries.

The centrifugal pump 10 comprises a pump body 1 1 defining a pump casing 13 incorporating a volute chamber 15, and a discharge outlet 17. An impeller 19 is rotatably supported within the pump body 1 1. A suction inlet 21 is provided in the pump body 1 through which the fluid can enter the impeller 19 along the rotating axis. The centrifugal pump 10 operates in known manner, with the slurry entering the impeller 19 being accelerated by the rotating impeller and flowing radially outwardly into the volute chamber 15 from where it discharges through the outlet 17.

In the arrangement illustrated, the pump casing 13 incorporates a pump casing liner 23 (also known as a frame plate insert) which can be removed and replaced when worn, as is well known for centrifugal pumps used in applications involving slurries. The pump 10 is typically installed in a flow line for a slurry processing application, with the suction inlet 21 coupled to a suction line section of the flow line and the discharge outlet 17 coupled to a discharge line section of the flow line.

The centrifugal pump 10 according to the embodiment incorporates a system 30 for monitoring the operation of the pump to detect, and initiate action, in relation to, an obstruction of flow through the pump, typically arising as a consequence of a blockage or other obstruction in the suction line or the discharge line. In the event of such an obstruction, slurry can stagnate within the volute chamber 15 of the pump 10 and the temperature of the stagnant slurry increases as the rotating impeller 19 spins within the slurry.

The monitoring system 30 comprises a means 31 responsive a temperature condition associated with the pump. Such means 31 comprises a temperature sensor 33. In this embodiment, the temperature sensor 33 comprises a temperature measuring device such as a resistance temperature detector. The temperature sensor 33 may be operable to actuate, an indication system (not shown) such as an alarm if the temperature being monitored attained a prescribed temperature condition. The temperature sensor 33 may also be operable to interrupt operation of the pump 10 upon attainment of the prescribed temperature condition or upon an increase in the temperature to a predetermined extent beyond the prescribed temperature condition. With the latter arrangement, the indication system would provide an indication of the presence of an obstruction without necessary interrupting operation of the pump, thereby identifying the need for some remedial action. If the problem is not remedied and the temperature continues to rise, the operation of the pump would be interrupted once the temperature has risen the predetermined extent beyond the prescribed temperature condition.

In the arrangement illustrated, the temperature sensor 33 is installed in a boss 35 formed integrally in the frame plate insert 23. The temperature sensor. 33 is connected to the remainder of the monitoring system 30 by terminal wire 37. With this arrangement, the temperature sensor 33 is not directly exposed to slurry within the pump 10 _r but rather is exposed to heat generated within the slurry as a consequence of heat transfer from the slurry through the frame plate insert 23. The centrifugal pump 10 operates in known manner to pump slurry along the flow line from the suction line section to the discharge line section. If the slurry flow rate falls below its settling velocity, solids can settle in the flow line, thereby causing a blockage. The blockage can lead to the slurry ceasing to flow, or at least being adversely retarded in its flow, through the centrifugal pump 10. Notwithstanding the blockage, the impeller 19 continues to rotate and so spins in the confined slurry within the pump. This action, provided a "paddle wheel effect", generating heat within the confined slurry. The monitoring system 30 detects if the temperature rises to a point where remedial action is required and initiates such action if necessary.

From the foregoing, it is evident that the present embodiment provides a simple yet highly effective arrangement for preventing operation of the centrifugal pump 10 in a potentially, dangerous condition occurring through an obstruction (such as a blockage) resulting in slurry ceasing to flow, or at least being adversely retarded in its flow, through the centrifugal pump.

It should be understood that the scope of the invention is not limited to the scope of the embodiment described.

In the embodiment described, the temperature sensor 33 is located on the frame plate insert 23 of the pump 10. Other arrangements are, of course, possible. By way of example, the temperature of any pressure retaining component of the pump could be monitored; for instance, the temperature sensor could be mounted on the pump casing, the throat bush or within the volute chamber.

Further, the invention is not necessarily limited to centrifugal pumps. The invention may have application to other pumps where as potentially dangerous condition could arise through a blockage or other obstruction to the flow of fluid being pumped. Still further, the invention is not limited to handling of slurries. The invention may have application to the handling of any appropriate fluid, including liquids (such as water) having essentially no or little solids content.

Modification and improvements can be made without departing from the scope of the inventions Throughout the specification arid claims, unless the context requires otherwise, the word "comprise" _, or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.