Patent Application
20080181798
The present invention relates to an apparatus and method for powering a fluid pump, and more particularly to an apparatus and method for powering the drive means of a fluid pump.
During drilling operations a number of different types of pumps are used to move and circulate fluids. These pumps all generally operate in the same manner being two or three-cylinder piston pumps whose replaceable pistons travel in replaceable liners that are driven by a crank shaft. In some pumps the crank shaft is itself driven, via gears, by a drive shaft (also sometimes called a pinion shaft). The crank shaft, or the drive shaft as the case may be, is actuated by an engine or a motor. Examples of such pumps used in connection with drilling operations include water pumps, slurry pumps, nitrogen pumps and cement pumps. Another example of such a pump is a mud pump. During drilling operations for oil and gas, a mixture of clays and chemicals and water, is pumped down the drill pipe to lubricate and cool the drilling bit and to flush out the cuttings and to strengthen the sides of the hole. This mixture is commonly referred to as drilling mud. A large reciprocating pump known as a mud pump is used to circulate the drilling mud.
As shown in
The present invention is directed to apparatus and method of powering the drive means of a fluid pump.
Accordingly, in one aspect of the invention, the invention comprises an apparatus for powering the drive means of a fluid pump, the apparatus comprising:
In one embodiment the fluid pump is a mud pump. In another embodiment, the rotor is a hollow rotor, and the drive means of the fluid pump is a drive shaft, and the hollow rotor is adapted to slide onto and attach to the drive shaft. In one embodiment, the rotor is a hollow rotor, and the drive means of the fluid pump is a crank shaft, and the hollow rotor is adapted to slide onto and attach to the crank shaft. In one embodiment, the electric motor is supported by the drive means of the fluid pump.
In one embodiment, the restraint means comprises a torque arm being attached at one end to the electric motor. In another embodiment, there is means for restraining the distal end of the torque arm. In embodiments of the present invention, the motor may be an AC induction electric motor, a DC traction electric motor, DC switch reluctant electric motor or a permanent magnet electric motor. In one embodiment, the rotor is hollow, the interior of the hollow rotor is tapered, and the rotor is attached to the drive means using a taper lock.
In another aspect of the present invention, the invention comprises an apparatus for powering the drive shaft of a fluid pump, the apparatus comprising:
In another aspect of the invention, the invention comprises an apparatus for powering a mud pump, the mud pump having a base and a drive shaft, the drive shaft having a longitudinal axis, the apparatus comprising:
In another aspect of the present invention, the invention comprises a method of powering the drive means of a fluid pump using an electric motor having a rotor and a stator, the method comprising the steps of:
The invention will now be described by way of an exemplary embodiment with reference to the accompanying simplified, diagrammatic, not-to-scale drawings. In the drawings:
Scope
When describing the present invention, all terms not defined herein have their common art-recognized meanings. To the extent that the following description is of a specific embodiment or a particular use of the invention, it is intended to be illustrative only, and not limiting of the claimed invention. The following description is intended to cover all alternatives, modifications and equivalents that are included in the spirit and scope of the invention, as defined in the appended claims.
Definitions
In this patent the following words are intended to have the following meaning:
Description
The present invention is directed to an apparatus for powering the drive means of a fluid pump and to a method of powering a fluid pump. The drive means of a fluid pump can comprise a crank shaft that is rotated to reciprocate the pistons and connecting rods. Alternatively, the drive means may comprise a drive shaft connected to a crank shaft by any suitable gearing system. In this configuration, rotation of the drive shaft results in rotation of the crank shaft which in turn reciprocates the pistons. The present invention may be used with either configuration of drive means.
Use of the invention for powering a mud pump having a drive shaft connected to a crank shaft shall be described below and is shown in the Figures. However, the invention may be used with any fluid pump having just a crank shaft, or having a drive shaft connected to a crank shaft. Although the Figures depict a Gardner Denver™ mud pump, it will be understood the apparatus (10) can be used with any conventional mud pump including without limitation OEM™ pumps, National Oilwell™ pumps, Varco™ pumps and Emsco™ Pumps.
Mud pumps are used on drilling rigs to circulate drilling mud. The mud pump forces drilling mud down the drill string and into the borehole to lubricate and cool the drilling bit and to flush out the cuttings and to strengthen the sides of the hole. Mud pumps typically comprise a large two or three-cylinder reciprocating piston pump that is driven by a drive shaft connected to a crank shaft actuated by an engine or a motor. As shown in
The conventional manner of powering a mud pump (12) consists of the use of an engine or motor that has a shaft connected to a gearing system. The gearing system is in turn connected to the drive means of the mud pump by belts, chains or other means. It can be understood that in such a conventional system the engine or motor powers an intermediary component, namely the gearing system, which in turn powers the drive means of the mud pump. This configuration shall hereinafter be referred to as an “indirect drive system”. In indirect drive systems, the engine or motor is usually either rear or top mounted about the mud pump (12).
The apparatus (10) comprises an electric motor (16) having restraint means. As shown in the Figures, in one embodiment the restraint means may comprise an torque arm (18) that is attached to the electric motor and which extends outwards in a plane that is substantially perpendicular to longitudinal axis of the rotor (A). In one embodiment the weight of the electric motor (16) is supported by the drive shaft (22), or the crank shaft as the case may be, and the purpose of the torque arm (18) is to restrain rotational movement of the stator during operation of the electric motor. As shown in the Figures, the torque arm (18) and motor (16) may have complimentary bolt-holes to facilitate mounting of the torque arm using nuts and locking bolts. However, any other suitable method of releasably mounting the motor (16) to the torque arm (18) as would be employed by one skilled in the art may be selected. Releasable attachment facilitates easy maintenance and removal of the electric motor (16) if required. Alternatively, the electric motor (16) may be produced such that the torque arm (18) forms an integral piece thereof. For example, the torque arm may also serve as an end plate of the motor.
The apparatus (10) also has means to restrain movement of the end of the torque arm distal from the electric motor (19). The means may comprise an attachment with the fluid pump itself and the end of the torque arm may be attached to mud pump (12) by bolts, welding or other suitable means. However, having regard to the fluctuating torque loads placed on the torque arm (18), it is preferred, but not essential, to implement a configuration that allows for a small degree of free play. In the embodiment shown in the Figures, the end of the torque arm (19) is inserted between two restraining members (25) mounted to the base of the mud pump (23). The restraining members may simply comprise stopper blocks welded to the mud pump (12). There is a small gap between the edges of the torque arm (18) and the stopper blocks. This allows minor amounts of movement but restrains rotation of the stator (21) and the motor (16) as a whole. The means for restraining the end of the torque arm (18) may also comprise a single stopper block that is notched to accommodate the end of the torque arm. In further embodiments, the means for restraining the torque arm can comprise a spring-loaded attachment or a stopper block, or blocks, constructed of an elastomeric polymer.
The torque arm (18) can be made from any suitable material, but it must be strong enough to withstand the torque forces placed on it by virtue of the rotating motor rotor (20) coupled to the drive shaft (22) during pumping operations. Iron alloys and steel alloys have been found to be suitable. As shown in the Figures, in one embodiment, the torque arm (18) may be shaped like a tennis racquet having a shaft (17) and a hollow upper portion (19) through which the drive shaft (22) of the mud pump (12) may project to attach to the rotor (20) of the electric motor (16). However, such suggestion of shape is not intended to be limiting of the invention claimed herein, and any functional shape may be used. Although the Figures show the torque arm (18) extending down in a substantially vertical orientation, it can be understood that the torque arm (18) may extend in any direction and can releasably engage any suitable portion of the mud pump (12).
The electric motor (16) comprises a stator (21) and a rotor (20) that rotates inside the stator on a bearing system. Any suitable electric motor may be used, including without limitation, an AC induction motor, a DC traction motor, a DC switch reluctant motor or a permanent magnet motor. In one embodiment, because there is no gearing system being utilized, the electric motor selected must be able to generate sufficient torque for the intended application. The electric motor is connected to a source of electricity such as a generator using insulated cables, or any other suitable means commonly employed by those skilled in the art. There may preferably be an air gap between the rotor (20) and the stator (21). In one embodiment, a hollow bore electric motor is used which has a hollow rotor.
The electric motor may have an optional coolant system, if required (not shown in the Figures) for cooling the electric motor. The coolant system can be a liquid-cooled system or an air-cooled system, or both, depending on the needs of the electric motor. In one embodiment employing a liquid cooled system, coolant is held in a reservoir and is then pumped through filters to a coolant hose that supplies the stator (21). The coolant is circulated through the stator (21) through tubes drawing heat from the stator (21). The heated coolant is removed from the stator (21) using a return hose or tube, or a plurality of hoses, and is cooled using a cooling radiator or shell and tube cooler system. After being cooled, the coolant is returned to the reservoir. The system has a pump to circulate the coolant and has flow, and temperature controls and monitors. Dependant on the operation climate, the coolant may be a water/glycol mix, and may include a corrosion inhibitor.
In another embodiment, the stator (21) and rotor (20) can be air cooled by force blowing large volumes of air across these components. An inlet can be created using a plate at one side of the stator (not shown in the Figures) and an outlet may be created at the other end in a similar manner. Air that has been filtered to remove debris and particles is passed across the stator (21) and rotor (20) using a fan from the inlet to the outlet, thereby cooling the motor.
As shown in
As shown in
It will be understood that with the rotor (20) directly attached to the drive shaft (22), rotation of the rotor (20) will cause corresponding simultaneous rotation of the drive shaft (22). Accordingly, the apparatus (10) constitutes a direct drive system wherein the drive means of the fluid pump is directly driven without the need for intermediary gears, belts or chains. The direct drive system of the present invention has relatively fewer components, requires relatively lower levels of maintenance and has a relatively lower cost of production. It can be understood that if the drive means of the fluid pump comprises a crank shaft alone, the rotor may be attached to a crank shaft in the manner described above.
Although a hollow bore electric motor is particularly suitable, an electric motor having a solid shaft type rotor may also be used to practice the present invention. The solid rotor shaft may be coupled with the end of the drive shaft (22), or crank shaft as the case may be, by any suitable means such as bolted coupler. Additional support can be provided to support the weight of the electric motor if required. Such support may be provided by struts attached to the fluid pump, or by other suitable support mechanisms. In one embodiment, the torque arm (18) may be adapted such that it supports the weight of the electric motor (16).
More than one electric motor may be employed if higher levels of horsepower are required. For example, in one embodiment an electric motor may be mounted on both ends of the drive shaft (22). Generally, horsepower requirements of approximately 1600 horse power and higher require the use of more than one motor.
The motor (16) is optionally shrouded with guard plates (not shown in the Figures), which may be constructed from any suitable metallic material including twin plate steel.
The present invention is also directed to a method of powering the drive means of a fluid pump using an electric motor in a direct drive system. Employing the principles demonstrated in the apparatus (10), the method involves attaching the rotor of the electric motor to the drive shaft (22) or crank shaft of the fluid pump (12) and then and supplying electrical power to the electric motor (16) whilst restraining the electric motor to prevent rotation of the stator (21).
As will be apparent to those skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the scope of the invention claimed herein.
