Rotary Gas Compressor

Abstract

Method and apparatus for a compressor for compressing air, gases and vapors isothermally using a liquid stream to compress the gas; the liquid issuing from an impeller intermittently, with the gas being entrained between these liquid pulses and compressed by the liquid; the liquid having high kinetic energy when leaving the impeller and in slowing the kinetic energy is converted to pressure for both the liquid and entrained gas. Also, this compressor may be used advantageously to compress vapors, wherein the liquid is the same fluid as the gas, in which case condensation of the gas to the liquid occurs, and work of compression is reduced.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to devices for compressing gases, air and vapors, in which a liquid is in intimate contact with the gas or vapor to be compressed.

DESCRIPTION OF PRIOR ART

There are numerous devices and machines available for compressing a gas or a vapor. In some of these machines a liquid is rotated inside an eccentric casing, so that the machine rotor will cause the liquid to pulsate and the space between the rotor blades is increased or decreased, and this variation compresses the gas. These machines are called liquid piston type machines. Another device is the jet ejector compressor, where a stream of liquid or gas is used to entrain the gas or vapor to be compressed, and the kinetic energy of the stream is converted in a diverging nozzle to a pressure.

The main disadvantage of the liquid piston type machine is its poor efficiency, since the liquid is rotated in the machine and requires relatively large power input for compressing the gas. In the ejector compressor, the velocity of the liquid stream is limited and it entrains poorly of any gas; therefore the efficiency of the device is very poor. The available kinetic energy in the liquid stream is high, but due to poor entrainment of the gas by the liquid, results for the device are poor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an end view of the compressor casing, showing the exterior.

FIG. 2 is a side view and a section of the casing and the impeller of the compressor.

FIG. 3 is a side view and a section of the impeller, and

Fig. 4 is an end view of the impeller, showing the fluid passages.

DESCRIPTION OF PREFERRED EMBODIMENTS

It is an object of this invention to provide a method and a device for compressing gases or vapors essentially isothermally in which the kinetic energy contained by a liquid stream is used to compress said gas to a higher pressure where the liquid in slowing in speed will increase its pressure and increase the pressure of the gas being entrained in it. Also, it is an object of this invention to provide a method and a device in which the gas may be partially or fully be condensed in the liquid stream thereby lowering the work of compression; this occurring when the gas or vapor being compressed is the same fluid as the liquid; that is, the gas being compressed is the vapor phase of the fluid, and the liquid being used for as the motive fluid is the liquid phase of the fluid.

Referring to FIG. 1, there is shown an end view of the compressor. 10 is the compressor casing, 11 is the liquid inlet, 12 is the gas or vapor inlet, and 13 is the outlet.

In FIG. 2, a side view of the compressor is shown. The impeller 22 is rotated by shaft 28, supported by bearings and sealed by packing 23 and stuffing box 24. Alternately a mechanical seal could be used. The liquid that is used as the motive fluid enters through opening 11, passes through the impeller 22 and leaves the impeller at a high velocity and entering the throat section 21 and from there the diffuser section 29 in the casing 10. After leaving the diffuser at a higher pressure, and at a lower velocity, the gas and liquid mixture is collected in annular space 30, and from there passes out through opening 13. The liquid entrains gas from annular space 31, and the gas enters the annular space from outside through opening 12.

In FIG. 3, the impeller 22 is shown in more detail. 38 is the fluid passage, and 36 is the opening for the drive shaft.

In FIG. 4, the impeller is shown, with 22 being the impeller and 38 being the fluid passage.

In operation, the compressor functions in a manner similar to a jet ejector compressor. A motive fluid is accelerated in a passage in the impeller to a high velocity; this corresponds to the motive fluid nozzle in a jet ejector. However, the fluid stream issuing from the impeller, when it rotates, is not continuous as seen by the compressor casing, since in this particular instance, the impeller has four fluid passages, with solid material between. Therefore, the flow from impeller, as seen by the compressor casing, is pulsating, with empty spaces between the high speed liquid; these empty spaces being filled by the gas from the annular spaces, item 31, FIG. 2, and the gas being rapidly moved with the liquid to the outer annular space 30, and from there to discharge. This pulsating action improves the entrainment of the gas by the liquid, and more fully utilize the kinetic energy available in the liquid stream.

The sizing of the fluid passages and the calculations pertaining to same are fully described in thermodynamics literature for jet ejectors and for steam injectors. The space of the passage 38 in FIG. 3, would be either converging for liquids that do not vaporize when leaving the passage; or the passage could be diverging at its outlet for fluids that will vaporize either partially or fully when leaving the passage. Of the non-vaporizing liquids, water would be an example, and of the partially vaporizing types, butane would be an example, both at atmospheric temperatures, and at low pressures. As illustrated in FIGS. 2-4, passageways 38 comprise a converging section nearest the center of the impeller but are at least non-converging at the discharge section. Preferably, the at least non-converging section is a diverging section for better taking advantage of the energy available in the motive fluid to effect higher effluent velocities thereof.

The fluid passages shown in FIG. 4, item 38, can be radial as illustrated, or be forward or backward curved, depending on the fluid used or the shape of the passages. Also, the throat section 21, FIG. 2, may have vanes of proper shape to prevent circular motion of the fluid after it leaves the impeller. Vanes of this type are commonly used in turbines and pumps and are not described herein. Number of fluid passages in FIG. 4 is indicated to be four, but this number would be as required when calculations are made pertaining to the size of the passages, and the frequency of pulses of liquid required to maintain suitable pressure and volume relationships inside the compressor; also, the rotational speed of the impeller would enter into these calculations.

Normally, the amount of liquid as compared to the amount of gas or vapor, is large. Therefore, when compressing a gas, the heat of compression from the gas is transferred to the liquid, resulting in a temperature increase for the liquid, as well as the gas. This temperature increase is much less than it would be for the gas alone, resulting in nearly isothermal compression, and therefore reduced work of compression, as compared to isentropic compression that is often used in rotary compressors. Also, if a liquid that will expand in the impeller is used, with an expanding fluid passage, the temperature of the motive fluid is lowered, and the fluid velocity greatly increased, resulting in much better efficiency for the compressor; this is similar to the function of converging-diverging diverging nozzles in jet ejectors.

The operation of the compressor may be inferred from the above descriptive matter. A liquid source is connected to the impeller inlet, and a gas or vapor source is connected to the gas inlet, FIG. 1, 11 and 12, respectively. Discharge from the compressor is from 13, FIG. 1. A suitable power source, such as an electric motor, is connected to shaft 28, FIG. 2, causing the shaft to rotate. The liquid is accelerated by the action of the impeller, and as it passes through the annular space 31, FIG. 2, in pulsating flow, it entrains the gas and carries it to annular space 30, and from there to discharge.

Materials of construction for the compressor would be similar to those used to make pumps for pumping liquids. Cast iron, steel, bronze, brass, stainless steel and various plastics could be used.

Claims

What is claimed new is as follows:

1. A machine for compressing gaseous fluid and having the major components of:

a. an impeller for accelerating a motive fluid to a high velocity; said impeller having a plurality of passageways that comprise respective initially converging sections as the passageways extend outwardly from the center of said impeller and at least non-converging sections exteriorly of said converging sections; said non-converging sections defining the discharge passageways of said impeller for more effective use of the available energy of said motive fluid which has been accelerated to high velocity whereby a motive fluid may be partially vaporized at the decreasing pressure due to said high velocity to attain even higher velocities for more effective entrainment of said gaseous fluid; and

b. a casing for the compressor, said casing including a diffuser section for slowing the high speed mixture of fluids and converting the kinetic energy of the stream to pressure, said diffuser section containing a throat section where the mixing of the motive fluid from the impeller and the vapor to be compressed occurs, and a plurality of suitable annular spaces disposed peripherally exteriorly of said impeller respectively for the entering gaseous fluid and for the mixture of motive fluid and gaseous fluid and respective apertures for the entering gaseous fluid and the effluent mixture of fluids.

2. The machine of claim 1 wherein said at least non-converging section is diverging.