Crossing spiral compressor/pump

Details Crossing spiral compressor/pump Crossing spiral compressor/pump

1999-11-19

2002-03-26

Lopez, F. Daniel (Department: 3745)

Rotary kinetic fluid motors or pumps

Runner has spirally arranged blade or fluid passage

Extending along runner axis

C416S235000

Reexamination Certificate

active

06361271

ABSTRACT:

TECHNICAL FIELD
This invention relates to the general field of compressors and pumps and more particularly to a compressor/pump having a crossing spiral fluid flow path.
BACKGROUND OF THE INVENTION
A crossing spiral compressor/pump is a high-speed rotary machine that accomplishes compression or pressurization of fluid by imparting a velocity head to each fluid particle as it passes through the machine's rotor flow channels and then converting that velocity head into a pressure head in the bore flow channels of a stator housing that function as vaneless diffusers. While in this respect a crossing spiral compressor/pump has some characteristics in common with a centrifugal compressor or centrifugal pump, the primary flow in a crossing spiral compressor/pump is axial with a double helical spin, while in a centrifugal compressor the primary flow is radial with no spin. The fluid particles passing through a crossing spiral compressor/pump travel in a tight pitch helical flow pattern within loosely pitched spiral flow channels on the outside of the rotor and inside the stator housing bore. The rotor flow channels are essentially half circles with their open surface facing outward adjacent to the bore flow channels. The bore flow channels are essentially half circles with their open surfaces facing inward adjacent to the rotor flow channels. The adjacent rotor and bore flow half circle flow channels function together as a combined channel that is essentially circular. Within the combined channels, the fluid particles travel along helical streamlines, the centerline of the helix coinciding with the center of the combined rotor and bore spiral channels. This flow pattern causes each fluid particle to pass through the rotor channels many times while the fluid particles are traveling through the crossing spiral compressor/pump, each time acquiring kinetic energy. After each pass through the rotor flow channels, the fluid particles reenter the adjacent stator housing bore channels where they convert their kinetic or velocity energy into potential or pressure energy. This produces an axial pressure gradient in the rotor and stator housing bore flow channels.
The multiple passes through the rotor flow channels (regenerative flow pattern) allows a crossing spiral compressor/pump to produce discharge heads of up to fifteen (15) times those produced by a centrifugal compressor operating at equal tip speeds. Since the cross-sectional area of the flow channels in a crossing spiral compressor/pump is usually smaller than the cross-sectional area of the radial flow in a centrifugal compressor, a crossing spiral compressor/pump would normally operate at flows which are lower than the flows of a centrifugal compressor having an equal impeller diameter and operating at an equal tip speed. These high-head, low-flow performance characteristics of a crossing spiral compressor/pump make it well suited to a number of applications where a reciprocating compressor, a rotary displacement compressor, or a low specific-speed centrifugal compressor would not be as well suited.
A crossing spiral compressor/pump can be utilized as a turbine by supplying it with a high pressure working fluid, dropping fluid pressure through the machine, and extracting the resulting shaft horsepower with a generator. Hence the terms “compressor/turbine” or “pump/turbine” are used throughout this application. During normal operation, the crossing spiral machine can be converted from a compressor/pump into a turbine by reducing and reversing the discharge head pressure.
Among the advantages of a crossing spiral compressor/pump or a crossing spiral turbine are:
(a) simple, reliable design with only one rotating assembly;
(b) stable, surge-free operation over a wide range of operating conditions (i.e. from full flow with low discharge head pressure to no flow with high discharge head pressure)
(c) long operating life (e.g., 40,000 hours) limited mainly by their bearings;
(d) freedom from wear product and oil contamination since there are no rubbing or lubricated surfaces utilized;
(e) only one stage required compared to multi-stage centrifugal compressor/pump assemblies of equal pressure rise and speed; and
(f) higher operating efficiencies when compared to a very low specific-speed (high head pressure, low flow, and low impeller speed) centrifugal compressor.
On the other hand, a crossing spiral compressor/pump or turbine cannot compete with a moderate to high specific-speed centrifugal compressor, in view of their relative efficiencies. While the best efficiency of a centrifugal compressor at a high specific-speed (low head and high flow) operating condition would be on the order of seventy-eight percent (78%), at a low specific-speed operating condition a centrifugal compressor could have an efficiency of less than twenty percent (20%). A crossing spiral compressor/pump operating at the same low specific-speed and at its best flow can have efficiencies of about fifty-five percent (55%)
The flow in a crossing spiral compressor/pump can be visualized as two fluid streams that first merge and then divide as they pass through the compressor/pump.
While the unique capabilities of a crossing spiral compressor/pump would seem to offer many applications, the low flow limitation severely curtail their widespread utilization.
Permanent magnet motors and generators, on the other hand, are used widely in many varied applications. This type of motor/generator has a stationary field coil and a rotatable armature of permanent magnet(s). In recent years, high energy product permanent magnets having significant energy increases have become available. Samarium cobalt permanent magnets having an energy product of twenty-seven (27) megagauss-oersted (mgo) are now readily available and neodymium-iron-boron magnets with an energy product of thirty-five (35) megagauss-oersted are also available. Even further increases of mgo to over 45 megagauss-oersted promise to be available soon. The use of such high energy product permanent magnets permits smaller machines capable of supplying higher power outputs.
The permanent magnet rotor may comprise a plurality of equally spaced magnetic poles of alternating polarity or may even be a sintered one-piece magnet with radial orientation. The stator would normally include a plurality of windings and magnet poles of alternating polarity. In a generator mode, rotation of the rotor causes the permanent magnets to pass by the stator poles and coils and thereby induces an electric current to flow in each of the coils. In the motor mode, electrical current is passed through the coils, which will cause the permanent magnet rotor to rotate.
SUMMARY OF THE INVENTION
A crossing spiral flow path compressor is a rotary machine having a rotor disposed to rotate within a stator housing bore, with the rotor having a plurality of channels spiraling in one direction and the stator housing bore having a plurality of channels spiraling in the reverse or opposite direction. The rotor and stator housing bore channels would be separated by narrow blades (significantly narrower than the width of the channels) with minimal blocking of backflow around the blades.
The crossing spiral compressor/pump may be integrated with a permanent magnet motor/generator to achieve fluid dynamic characteristics that are otherwise not readily obtainable. The crossing spiral compressor/pump and permanent magnet motor/generator are disposed in a housing with the crossing spiral compressor/pump at one end and typically the permanent magnet motor/generator at the other end. The crossing spiral compressor/pump rotor and the permanent magnet rotor form a common rotor which is rotatable mounted within this housing typically by bearings at the ends of the common rotor. Alternately, the common rotor may be supported by bearings at the ends of the crossing spiral compressor/pump section of the rotor with the motor/generator section of the rotor overhanging the bearing located between the compressor/pump and the motor/generator.
In one embodiment the flow is intro

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