Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Nozzle discharging onto motor runner
Reexamination Certificate
2001-01-31
2003-03-04
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Nozzle discharging onto motor runner
C415S903000
Reexamination Certificate
active
06527513
ABSTRACT:
The present invention relates to turbines suitable for down-hole applications such as bore-hole drilling and driving various down-hole tools.
Conventional turbines for down-hole use generally comprise a longitudinally extending turbine stage array in which the drive fluid passes substantially axially through a multiplicity of turbine stages connected in series. Particular disadvantages of this type of arrangement include relatively low efficiency due to the rapid increase of efficiency losses with increasing number of turbine stages, and the considerable length required to achieve any useful torque levels. Typical commercially available turbines of this type having of the order of 100 to 200 turbine stages, have a length of around 20 m and longer. Such a length presents considerable restrictions on the use of such turbines in non-rectilinear drilling e.g. directional drilling situations, because of restrictions on minimum radius of curvature of kick-off which can be used, as well as in drilling operations using coiled tubing because of the large lubricators required to accommodate the turbine together with the drilling tools and other equipment required. This in turn gives rise to substantial practical problems in the positioning of the injector at a suitable height, above the lubricator.
It is an object of the present invention to avoid or minimise one or more of the above disadvantages and/or problems.
It has now been found that a compact, high power, turbine can be achieved by means of a combined redial impulse and drag turbine in which substantially increased turbine drive output is obtained within a given length of turbine.
The present invention provides a turbine suitable for use in down-hole drilling and the like, and comprising a tubular casing enclosing a chamber having rotatably mounted therein a rotor comprising at least one turbine wheel blade array with an annular array of angularly distributed blades orientated with drive fluid receiving faces thereof facing generally rearwardly of a forward direction of rotation of the rotor, and a generally axially extending inner drive fluid passage generally radially inwardly of said rotor, said casing having a generally axially extending outer drive fluid passage, one of said inner and outer drive fluid passages constituting a drive fluid supply passage and being provided with at least one outlet nozzle formed and arranged for directing at least one jet of drive fluid onto said blade drive fluid receiving faces of said at least one blade array as said blades traverse said nozzle for imparting rotary drive to said rotor, the other constituting a drive fluid exhaust passage and being provided with at least one exhaust aperture for exhausting drive fluid from said at least one turbine wheel blade array.
Preferably the turbine has a plurality, advantageously, a multiplicity, of said turbine wheel means disposed in an array of parallel turbine wheels extending longitudinally along the central rotational axis of the turbine with respective parallel drive fluid supply jets.
In a particularly preferred aspect the present invention provides a turbine suitable for use in down-hole drilling and the like, and comprising a tubular casing enclosing a chamber having rotatably mounted therein a rotor having at least two turbine wheel blade arrays each with an annular array of angularly distributed blades orientated with drive fluid receiving faces thereof facing generally rearwardly of a forward direction of rotation of the rotor, and a generally axially extending inner drive fluid passage generally radially inwardly of each said turbine wheel blade array, said casing having a respective generally axially extending outer drive fluid passage associated with each said turbine wheel blade array, one of said inner and outer drive fluid passages constituting a drive fluid supply passage and being provided with at least one outlet nozzle formed and arranged for directing at least one jet of drive fluid onto said blade drive fluid receiving faces as said blades traverse said at least one nozzle for imparting rotary drive to said rotor, the other constituting a drive fluid exhaust passage and being provided with at least one exhaust aperture for exhausting drive fluid from said turbine wheel blade arrays, neighbouring turbine wheel blade arrays being axially spaced apart from each other and provided with drive fluid return flow passages therebetween connecting the exhaust passage of an upstream turbine wheel blade array to the supply passage of a downstream turbine wheel blade array for serial interconnection of said turbine wheel blade arrays.
Instead of, or in addition to providing a said inner or outer drive fluid passage for exhausting of drive fluid from the chamber, there could be provided exhaust apertures in axial end wall means of chamber, though such an arrangement would generally be less preferred due to the difficulties in manufacture and sealing.
In yet another variant of the present invention, both the drive fluid supply and exhaust passage means could be provided in the casing (i.e. radially outwardly of the rotor) with drive fluid entering the chamber from the supply passage via nozzle means to impact the turbine blade means and drive them forward, and then exhausting from the chamber via outlet apertures angularly spaced from the nozzle means in a downstream direction, into the exhaust passages.
Thus essentially the turbine of the present invention is of a radial (as opposed to axial) flow nature with motive fluid moves between radially (as opposed to axially) spaced apart positions to drive the turbine blade means. This enables the performance, in terms of torque and power characteristics, of the turbines of the present invention to be readily varied by simply changing the nozzle size—without at the same time having to redesign and replace all the turbine blades as is generally the case with conventional axial flow turbines when any changes in fluid velocity and/or fluid density are made. Thus, for example, reducing the nozzle size will (assuming constant flow rate) increase the (fluid jet) flow velocity thereby increasing torque. This will also increase the operating speed of the turbine and thereby the power, as well as increasing back pressure. Similarly increasing flow rate while keeping nozzle size constant will also increase the (fluid jet) flow velocity thereby increasing torque as well as giving an increase in the operating speed of the turbine and thereby the power and increasing back pressure. Alternatively, increasing the nozzle size while keeping the (fluid jet) flow velocity constant—by increasing the flow rate, would increase torque and power without increasing the turbine speed or back pressure. If desired, torque can also be increased by increasing the density of the drive fluid (assuming constant fluid flow rate and velocity) which increases the flow mass.
It will be appreciated that individual nozzle size can be increased longitudinally and/or angularly of the turbine, and that the number of nozzles for the or each turbine wheel blade array can also be varied.
The turbine blades can also have their axial extent longitudinally of the turbine increased so as to increase the parallel mass flow of motive fluid through the or each turbine wheel array, without suffering the severe losses encountered with conventional multi-stage turbines comprising axially extending arrays of axially driven serially connected turbine blade arrays.
Another advantage of the turbines of the present invention that may be mentioned is the circumferential fluid velocity distribution over the turbine blades is, due to the generally radial disposition of the said blades, substantially constant and thus very efficient in comparison with an axial turbine where the velocity distribution varies over the length of the blade and thus losses are caused through hydrodynamic miss-match of fluid velocity and circumferential blade velocity.
The turbines of the present invention also have some significant advantages over positive displacement motors in t
Stewart Kenneth Roderick
Van Drentham-Susman Hector F.A.
Casperson John R
Look Edward K.
Nguyen Ninh
Rotech Holdings Limited
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