US20090081031A1

US20090081031A1 - Vertical vapor compressor

Info

Publication number: US20090081031A1
Application number: US11/904,318
Authority: US
Inventors: Dennis E. Koopman; Richard Z. Talalaj
Original assignee: Individual
Current assignee: Spirax UltraPure LLC
Priority date: 2007-09-26
Filing date: 2007-09-26
Publication date: 2009-03-26
Also published as: WO2009042004A1

Abstract

A vapor compressor for use with a distillation system, the compressor including a housing defining an interior volume. The housing includes an inlet and an outlet. A shaft has a first end and a second end and extends along a longitudinal axis of the housing. A first compression stage includes a first impeller and a first stator, the first impeller including a first plurality of impeller blades having a first dimension. The first stator includes a first plurality of stator blades having a second dimension. A second compression stage includes a second impeller and a second stator, the second impeller including a second plurality of impeller blades having a third dimension. The second stator includes a second plurality of stator blades having a fourth dimension. The first dimension and the third dimension are measured along corresponding portions of the first plurality of impeller blades and the second plurality of impeller blades, and the first dimension is greater than the third dimension.

Description

TECHNICAL FIELD

The present invention relates generally to vapor compression within a distillation system. More particularly, the present invention relates to a vertically oriented vapor compressor for use in a distillation system.

BACKGROUND OF THE INVENTION

Distillation systems are known in the art as a means for purifying water used in various applications. For example, many pharmaceutical applications dictate that stringent distillate purity requirements and standards be met; standards that are not achieved by the use of public water sources. As such, on-site distillation is frequently utilized.
Existing distillation systems include an evaporator and a compressor. Generally, feed water enters the primary, or feed water, side of the evaporator where the feed water is heated until it transitions from a liquid phase to a vapor phase. The water vapor is then drawn from a vapor chamber of the evaporator by the compressor. The compressor is designed to compress the vapor to a higher energy level and pump the vapor back into a secondary, or distillate, side of the evaporator. The primary and secondary sides of the evaporator are segregated from each other such that the vapor pumped into the secondary side by the compressor is not re-contaminated by the feed water on the primary side. The higher energy vapor in the secondary side of the evaporator condenses to distillate transferring its energy to the feed water on the primary side of the evaporator. Next, the distillate is drawn from the secondary side of the evaporator, such as by distillate pump, and may undergo further operations, such as deaeration, cooling, etc.
Distillation systems of the prior art often have included horizontally mounted, single stage vapor compressors. The use of single stage vapor compressors often requires that the vapor compressor be operated at high rates of revolution, often as high as 12,000 revolutions per minute (RPM), to achieve the desired volumetric flow rate of distillate. As would be expected, operating the compressor at higher RPMs generates greater stresses within the compressor, increases operating noise levels, and increases the consumption of energy. In addition, higher RPMs often lead to increased wear on components of the compressor, such as shaft seals and bearing assemblies that rotationally support the shaft of the compressor. Along with increased maintenance costs due to component wear, a greater potential for contamination of the purified distillate exists due to the increased amounts of wear products from the components, most notably the bearing assemblies.

SUMMARY OF THE INVENTION

According to one aspect, the present invention provides a vapor compressor for use with a distillation system, the compressor including a housing defining an interior volume. The housing includes an inlet and an outlet. A shaft has a first end and a second end and extends along a longitudinal axis of the housing. A first compression stage includes a first impeller and a first stator, the first impeller including a first plurality of impeller blades having a first dimension. The first stator includes a first plurality of stator blades having a second dimension. A second compression stage includes a second impeller and a second stator, the second impeller including a second plurality of impeller blades having a third dimension. The second stator includes a second plurality of stator blades having a fourth dimension. The first dimension and the third dimension are measured along corresponding portions of the first plurality of impeller blades and the second plurality of impeller blades, and the first dimension is greater than the third dimension.
Another aspect of the invention provides a vapor compressor for use with a distillation system, the compressor including a housing defining an interior volume. The housing includes a cylindrical sidewall, an inlet and an outlet. A shaft has a first end and a second end and extends along a longitudinal axis of the housing. A first compression stage includes a first impeller and a first stator, the first impeller including a first plurality of impeller blades. The first stator includes a first back plate, a first plurality of stator blades and a first cylindrical sidewall extending upwardly from the first back plate, thereby defining a first cylindrical volume. The first impeller is disposed within the first cylindrical volume of the first stator. A second compression stage includes a second impeller and a second stator, the second impeller including a second plurality of impeller blades. The second stator includes a second back plate, a second plurality of stator blades and a second cylindrical sidewall extending upwardly from the second back plate, thereby defining a second cylindrical volume. The second impeller is disposed within the second cylindrical volume of the second stator. The longitudinal axis of the vapor compressor is vertically oriented.
In accordance with a further aspect, the invention provides a vapor compressor for use with a distillation system, the compressor including a housing defining an interior volume. The housing includes a cylindrical sidewall, an inlet and an outlet. A shaft has a first end and a second end and the shaft extends along a longitudinal axis of the housing. A first compression stage includes a first impeller and a first stator, the first impeller including a first plurality of impeller blades. The first stator includes a first back plate defining a first central aperture and a first cylindrical sidewall extending upwardly from the first back plate, thereby defining a first cylindrical volume. The first impeller is disposed within the first cylindrical volume of the first stator. A second compression stage includes a second impeller and a second stator. The second impeller includes a second plurality of impeller blades, each second impeller blade including a blade tip extending upwardly therefrom. The second stator includes a second back plate and a second cylindrical sidewall extending upwardly from the second back plate, thereby defining a second cylindrical volume. The second impeller is disposed within the second cylindrical volume of the second stator. The blade tips of the second plurality of impeller blades extend upwardly through the first central aperture of the first stator.
Other objects, features and aspects for the present invention are discussed in greater detail below. The accompanying drawings are incorporated in and constitute a part of this specification, and illustrate one or more embodiments of the invention. These drawings, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, to one of ordinary skill in the art, is set forth more particularly in the remainder of this specification, including reference to the accompanying drawings, in which;

FIG. 1 is a perspective, cross-sectional view of a vertically oriented vapor compressor in accordance with an embodiment of the present invention;

FIG. 2 is a perspective, exploded view of the vapor compressor as shown in FIG. 1;

FIG. 3 is an exploded perspective, partial cross-sectional view of a compression stage of the vapor compressor as shown in FIG. 1;

FIG. 4 is a bottom perspective view of a deflector plate of the vapor compressor as shown in FIG. 1; and

FIG. 5 is a perspective, cross-sectional view of the vapor compressor as shown in FIG. 1, indicating the flow path of fluid through the compressor.

Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

It is to be understood by one of ordinary skill in the art that the discussion herein is a description of exemplary embodiments only, and is not intended as limiting of the broader aspects of the present invention, which broader aspects are embodied in the exemplary constructions.
FIGS. 1 and 2 illustrate a vertically oriented, centrifugal vapor compressor 100 in accordance with the present invention. Vapor compressor 100 includes multiple stages of stators 102 a, 102 b and 102 c and impellers 104 a, 104 b, 104 c and 104 d mounted about a shaft 106 within an interior volume defined by a housing including a housing body 108, a housing top plate 118, and a housing bottom plate 120. As shown and as discussed in greater detail below, each of impellers 104 a-104 c is rotatably received, or nested, within a respective one of stators 102 a-102 c, which are stacked within housing body 108. The bottom impeller 104 d is not received within a stator in the illustrated embodiment.
Housing body 108 includes a radially extending top flange 110 and a radially extending bottom flange 112 extending outwardly from the uppermost and lowermost peripheries, respectively, of housing sidewall 111. A top plate 118 defines an inlet 122 for receiving vapor from an evaporator (not shown) of a distillate system. A bottom plate 120 includes a recessed portion 126 and a flange portion 128 extending radially outward from the lower portion thereof. Bottom plate 120 also defines a central aperture 130 (FIG. 2) and an annular recess 132 adjacent shaft aperture 130. As shown, shaft 106 extends through aperture 130 for rotation with respect to the housing. Annular recess 132 is configured to receive a steam seal 134 which is secured in annular recess 132 by a steam seal cover 135. An outlet 136 extends tangentially from sidewall 111 of housing body 108. Outlet 136 is arranged and configured to facilitate pumping distillate and compressed vapor from compressor 100 back into the distillate side of the evaporator.
As best seen in FIG. 3, each stator 102 a-102 c includes a stator plate 138, a plurality of blades 142, and a cylindrical sidewall 150. Stator plate 138 defines an outlet aperture 140 that allows the passage of vapor from one compression stage of vapor compressor 100 to the next. Outlet aperture 140 is sized to rotatably receive an inducer 194 formed by blade tips 188 of the impeller of the following compression stage, as discussed in greater detail below. Each blade 142 includes a proximal end 146 adjacent outlet aperture 140 and a distal end 148 adjacent sidewall 150. During operation, when viewed from the top of vapor compressor 100, shaft 106 rotates in a clockwise direction, as indicated by arrow 101. As such, vapor passing through stator 102 will also be induced to rotate in clockwise direction 101. Because distal end 148 trails proximal end 146 of each blade 142 when viewed in a clockwise manner, the plurality of blades 142 facilitates the flow of vapor and distillate from sidewall 150 toward outlet aperture 140, where it moves to the following compression stage. Note, the blade height is the distance between the top and bottom edges of each blade. Blade height can be varied from each compression stage to the next, as discussed in greater detail below.
In the illustrated embodiment, each of impellers 104 a-104 d includes a bottom plate 156, a top plate 158, a plurality of blades 160, an impeller hub 164 and a mounting brace 178. Bottom plate 156 defines a central aperture (not shown) that is configured to receive impeller hub 164. Top plate 158 defines a central aperture 170 that is configured such that a blade tip 188 of each blade 160 extends therethrough, the plurality of blade tips 188 forming an inducer 194 of impeller 104.
As best seen in FIG. 3, the configuration of each blade 160 ensures that as impeller 104 is rotated by shaft 106 in clockwise direction 101, a proximal end 186 of each blade 160 that is adjacent central aperture 170 precedes a distal end 190 of the blade in the direction of rotation 101. As such, proximal end 186 engages vapor and distillate passing through central aperture 170 and “slings” the vapor and distillate outwardly away from the center of impeller 104 toward the outer periphery of the impeller.
Each blade 160 also preferably includes a blade tip 188 extending forwardly and upwardly from the top edge of proximal end 186 in the direction of rotation 101 of the impeller. Collectively, the plurality of blade tips 188 forms an inducer 194 for the corresponding impeller 104 and is configured to facilitate movement of vapor and distillate from one compression stage to the next. Distal end 190 of each blade 160 is bent slightly in the direction opposite of the direction of rotation 101. This facilitates the movement of the fluid outwardly from impeller 104 and into the stator 102 in which it is nested. Note, the blade height is the distance between the top and bottom edges of each blade. Blade height can be varied from each compression stage to the next, as discussed in greater detail below.
The cylindrical portion of impeller hub 164, which defines a shaft aperture, is inserted through the central aperture (not shown) of bottom plate 156. Mounting brace 178 is passed downwardly over impeller hub 164 such that the cylindrical portion is received in the central aperture of mounting brace 178. Each blade 160 is positioned on back plate 156 and each arm 180 of mounting brace 178 is configured to provide support to proximal end 186 of a respective blade 160. Top plate 158 is positioned on the top edges of the plurality of blades 160. The plurality of blade tips 188 extends forwardly through central aperture 170 of top plate 158. As such, the plurality of blade tips 188 extends slightly into stator 102 (FIGS. 1 and 5) of the preceding stage through outlet aperture 140 of stator 102.
Referring again to FIG. 1, a top end 202 of shaft 106 extends into the interior volume of the compressor housing and is contained therein in its entirety. Top end 202 of shaft 106 supports the components contained within the interior volume while bottom end 204 of shaft 106 (FIG. 2) supports those components of compressor 100 that are external to the housing. As best seen in FIG. 1, preferably, four compression stages are disposed within the housing. The first compression stage includes stator 102 a and impeller 104 a, the second compression stage includes stator 102 b and impeller 104 b, the third compression stage includes stator 102 c and impeller 104 c, and the fourth compression stage includes only impeller 104 d. Each impeller 104 a-104 c is received within its corresponding stator 102 a-102 c. Also, each impeller 104 a-104 c is keyed to shaft 106 such that as shaft 106 is rotated in clockwise direction 101 during operation, each impeller 104 a-104 c similarly rotates in clockwise direction 101 within its respective stator 102 a-102 c. Impeller 104 d of the fourth compression stage is similarly keyed to shaft 106 by an impeller key. Stators 102 a-102 c are non-rotatably supported within the housing body. Similarly, the impeller hubs of the various compression stages are separated from each other by a plurality of shaft spacers. As previously noted, the interior volume of the housing is separated from the outside environment by steam seal 134 that is secured in annular recess 132 of bottom plate 120 by steam seal cover 135 (FIG. 2).
A deflector plate 220 is non-rotatably secured to bottom end 204 of shaft 106 adjacent the outer surface of bottom plate 120. As best seen in FIG. 4, deflector plate 220 is disk-shaped and defines a central aperture 222 through which shaft 106 is received. A key slot 226 for receiving a key 228 (FIG. 1) is formed in central aperture 222 and non-rotatably secures deflector plate 220 to shaft 106. A plurality of blades 224 extend radially outwardly from the central portion of deflector plate 220 and assist in transferring heat from shaft 106 to the ambient environment, thereby mitigating the transmission of heat along shaft 106 to the remaining external components of vapor compressor 100. Deflector plate 220 is disposed within a housing 216 that includes an outer wall 218 extending between a top flange 217 and a bottom wall 219. A plurality of cooling apertures 221 are defined by outer wall 218 to allow the free flow of air through the housing and facilitate the detection of leaks.
A cylindrical bearing housing 230 rotatably supports bottom end 204 of shaft 106. Bearing housing 230 includes a top flange 232 extending radially outwardly therefrom and a first annular recessed portion 234 defined by the inner periphery of the top end of bearing housing 230. Top flange 232 is non-rotatably secured to bottom wall 219 of housing 216. First annular recessed portion 234 is configured to receive a front (top) bearing 236 that is secured therein by a front seal lock 238 that is secured to bottom wall 219 of housing 216. Bearing housing 230 also defines a second annular recessed portion 240 about the inner periphery of its bottom end. Second annular recessed portion 240 is configured to receive a rear (bottom) bearing 242 that is secured in place by a rear seal plate 244 that is non-rotatably secured to the bottom portion of bearing housing 230 such as by threaded fasteners. A bearing spacer 241 is also received in second annular recessed portion 240 and assists in maintaining rear bearing 242 in the proper position. Various embodiments of the compressor can be either driven by a motor connected directly to shaft 106 or indirectly belt driven by a remote motor.
Vapor compressor 100, and components thereof, can be constructed of varying materials, such as steel, stainless steel, plastic, aluminum, ceramic, or any other material that may be passive to the distillate being produced. The material selected may be dependent upon the end use for which the distillate is extended, such as drinking water, pharmaceutical manufacturing, or other process related industries. In addition, various manufacturing processes can be used in constructing the components of the vapor compressor, many of which are dependent upon the selected materials. For example, casting, injection molding, machining, sintering, or other various fabrication methods could be used. One skilled in the art would be able to select the appropriate manufacturing techniques based on the desired materials of construction and the like.

Operation

A distillation system typically includes an evaporator (not shown) having a primary, or feed, side and a secondary, or distillate, side that are segregated from each other. The feed side is configured to receive the liquid that is to be distilled and retain the liquid therein while it is heated to the point that it passes from a liquid phase to a vapor phase. The vapor travels upwardly through the evaporator, typically passing through a series of baffles to remove entrained droplets, to the uppermost portion, or vapor dome, of the evaporator. Next, the vapor is drawn from the vapor dome of the evaporator, such as by vapor compressor 100 of the present invention.
As best seen in FIG. 5, vapor, indicated by the flow arrows, is drawn into vapor compressor 100 through inlet 122 of top plate 118. Inducer 194 a, which comprises the plurality of blade tips 188, of impeller 104 a is arranged and configured to draw the vapor into impeller 104 a as shaft 106 is rotated in clockwise direction 101. Vapor drawn into impeller 104 a at proximal end 186 of blades 160 will be induced, or “slung,” outwardly along the respective blade 160 toward distal end 190 of blade 160. As the vapor is accelerated outwardly along each blade 160, the velocity of, and the pressure exerted on, the mass of vapor passing through impeller 104 a is increased. Upon exiting impeller 104 a, the vapor enters stator 102 a of the first compression stage.
As well as increasing the velocity and pressure of the vapor mass, impeller 104 induces the mass of vapor to rotate in the direction of operation 101. Therefore, as the vapor mass enters stator 102 a and is drawn downwardly through vapor compressor 100, the vapor mass encounters distal ends 148 of the plurality of stator blades 142. The curvature of each blade 142 causes the mass of vapor to flow inwardly along the plurality of blades 142 from distal ends 148 to proximal ends 146 that are positioned adjacent outlet aperture 140. In addition to being urged downwardly through vapor compressor 100 by impeller 104 a of the first compression stage, the mass of vapor is also pulled downwardly through the vapor compressor by impellers 104 b-104 d of the subsequent compression stages. As the mass of vapor moves along the plurality of blades 142 to outlet aperture 140, inducer 194 b of the second compression stage entrains the vapor mass into impeller 104 b of the second compression stage where the velocity and pressure of the vapor mass are further increased. The operation of the second compression stage and the third compression stage are the same as that of the first compression stage, and are therefore not further described.
As the vapor mass moves downwardly through subsequent compression stages within vapor compressor 100, the volumetric flow rate and the pressure exerted on the vapor mass are increased, causing the vapor mass to begin to transition from the vapor phase back to the liquid phase, resulting in purified distillate. As the vapor mass transitions into distillate, the overall volume of the mass of vapor and distillate is reduced. As such, the size of subsequent compression stages can be reduced. For example, in the embodiment shown, the blade heights of impellers 104 a and 104 b are greater than the blade heights of impellers 104 c and 104 d. Similarly, the blade heights of stators 102 a and 102 b are greater than the blade height of stator 102 c. However, alternate embodiments of vapor compressor 100 include compression stages that are all of the same size.
In this embodiment, the fourth compression stage includes impeller 104 d, but not a corresponding stator. Inducer 194 d of impeller 104 d moves the mass of distillate and vapor into impeller 104 d where further acceleration and compression occurs. Upon exiting impeller 104 d, the mass of distillate and vapor enters the lower volume of housing 108 and moves in clockwise direction 101 about recessed portion 126 of bottom plate 120 until it eventually exits vapor compressor 100 through outlet 136. After exiting vapor compressor 100, the fluid enters the distillate side of the evaporator (not shown) where it passes heat energy to liquid on the feed side of the evaporator. As energy is removed from the vapor mass and transferred to the feed side of the evaporator, the vapor mass further condenses into distillate. Next, the distillate is drawn out of the distillate side of the evaporator for any further operations that remain in the distillation process.
During operation, vapor compressor 100 can achieve a given volumetric flow rate while operating at a lower RPM than a typical single-stage compressor since vapor compressor 100 induces increases in pressure and flow rate through multiple stages, rather than just one. Reduced operating RPMs may lead to reductions in operating noise, energy consumption, and wear of the various components of the compressor. Reduction of wear of the various components also reduces the possibility that those wear products will eventually migrate into the distillate.
As previously noted, the interior volume of vapor compressor 100 is separated from the external environment by steam seal 134. However, if any leakage from the interior volume does occur, deflector plate 220 is rotatably secured to shaft 106 beneath steam seal 143. Any vapor and/or distillate passing through steam seal 134 along shaft 106 encounters deflector plate 220 prior to reaching the various other external components. Because deflector plate 220 is rotationally fixed to shaft 106, as it rotates, it will cause any condensation that reaches it to be “slung” outwardly away from shaft 106. In moving the high temperature vapor/distillate away from the shaft, deflector plate 220 helps to ensure that heat therefrom is not transmitted along the shaft. Additionally, rotation of deflector plate 220 causes shaft 106 to be cooled in its vicinity by the movement of ambient air caused by the movement of blades 224 of the deflector plate. As such, deflector plate 220 mitigates the migration of heat along shaft 106 from the internal volume of the vapor compressor 100 to the external components.
Bearing housing 230 is secured to the bottom wall of housing 216. Housing 216 functions as a void between the internal volume of vapor condenser 100 and the lubricants located within bearing housing 230. As such, any vapor/distillate that leaks past steam seal 134 enters the void formed by housing 216. Similarly, any leakage of lubricants or wear products past front bearing 236 also enter the void formed by housing 216. In addition to facilitating the detection of leaks, the void formed by housing 216 also helps prevent the migration of wear products from bearing 236 into the distillate and vapor compressor 100, as well as the entry of distillate into bearing housing 230.
While preferred embodiments of the invention have been shown and described, modifications and variations thereto may be practiced by those of ordinary skill in the art without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments may be interchanged without departing from the scope of the present invention. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention as further described in such appended claims.

Claims

1. A vapor compressor for use with a distillation system, comprising:

a housing defining an interior volume, the housing including an inlet and an outlet;

a shaft having a first end and a second end, the shaft extending along a longitudinal axis of the housing;

a first compression stage including a first impeller and a first stator, the first impeller including a first plurality of impeller blades having a first dimension in a direction parallel to the longitudinal axis of the housing, the first stator including a first plurality of stator blades having a second dimension in a direction parallel to the longitudinal axis of the housing; and

a second compression stage including a second impeller and a second stator, the second impeller including a second plurality of impeller blades having a third dimension in a direction parallel to the longitudinal axis of the housing, the second stator including a second plurality of stator blades having a fourth dimension in a direction parallel to the longitudinal axis of the housing;

wherein the first dimension and the third dimension are measured along corresponding portions of the first plurality of impeller blades and the second plurality of impeller blades, and the first dimension is greater than the third dimension.

2. The vapor compressor of claim 1, wherein the second dimension and the fourth dimension are measured along corresponding portions of the first plurality of stator blades and the second plurality of stator blades, and the third dimension is greater than the fourth dimension.

3. The vapor compressor of claim 1, wherein the longitudinal axis of the vapor compressor is vertically oriented.

4. The vapor compressor of claim 3, wherein the first end of the shaft is located within the internal volume defined by the housing and the second end of the shaft is disposed outside of the housing.

5. The vapor compressor of claim 4, wherein the first impeller and the second impeller are non-rotatably fixed adjacent to the first end of the shaft.

6. The vapor compressor of claim 4, wherein the second end of the shaft is rotatably supported by a bearing assembly disposed outside of the housing.

7. The vapor compressor of claim 6, further comprising:

a shaft aperture defined by the housing, the shaft passing through the shaft aperture; and

a seal received in the shaft aperture, the seal being disposed around the shaft;

wherein the bearing assembly and the seal are separated by an axial spacing portion of the shaft.

8. The vapor compressor of claim 7, further comprising a deflector plate fixed to the axial spacing portion of the shaft between the seal and the bearing assembly, the deflector plate rotating with the shaft.

9. The vapor compressor of claim 8, wherein the deflector plate includes a plurality of blades.

10. The vapor compressor of claim 1, wherein the first stator includes a first bottom plate and a first sidewall, the sidewall extending upwardly and defining a first cylindrical volume with the first bottom plate, wherein the first impeller is disposed within the first cylindrical volume of the first stator.

11. A vapor compressor for use with a distillation system, comprising:

a housing defining an interior volume, the housing including a cylindrical sidewall, an inlet and an outlet;

a first compression stage including a first impeller and a first stator, the first impeller including a first plurality of impeller blades, the first stator including a first back plate, a first plurality of stator blades and a first cylindrical sidewall extending upwardly from the first back plate, thereby defining a first cylindrical volume, the first impeller being disposed within the first cylindrical volume of the first stator; and

a second compression stage including a second impeller and a second stator, the second impeller including a second plurality of impeller blades, the second stator including a second back plate, a second plurality of stator blades and a second cylindrical sidewall extending upwardly from the second back plate, thereby defining a second cylindrical volume, the second impeller being disposed within the second cylindrical volume of the second stator,

wherein the longitudinal axis of the vapor compressor is vertically oriented.

12. The vapor compressor of claim 11, wherein the first compression stage is disposed between the inlet and the second compression stage.

13. The vapor compressor of claim 12, wherein the first cylindrical sidewall of the first stator and the second cylindrical sidewall of the second stator are adjacent to and concentric with the cylindrical sidewall of the housing.

14. The vapor compressor of claim 11, wherein the first back plate of the first impeller defines a first central aperture, each second impeller blade of the second impeller includes a blade tip extending upwardly therefrom, wherein each blade tip of the second plurality of impeller blades extends upwardly into the first central aperture of the first stator.

15. The vapor compressor of claim 11, wherein a first height of each of the plurality of first impeller blades is greater than a second height of each of the plurality of second impeller blades, wherein the first height and the second height are measured from a top edge to a bottom edge of the first impeller blade and the second impeller blade, respectively, in a direction parallel to the longitudinal axis of the housing.

16. The vapor compressor of claim 11, wherein the first end of the shaft is located within the internal volume defined by the housing and the second end of the shaft is disposed outside of the housing.

17. The vapor compressor of claim 16, wherein the second end of the shaft is rotatably supported by a bearing assembly disposed outside of the housing.

18. The vapor compressor of claim 17, further comprising:

19. The vapor compressor of claim 18, further comprising a deflector plate non-rotatably fixed to the axial spacing portion of the shaft between the seal and the bearing assembly, the deflector plate rotating with the shaft.

20. A vapor compressor for use with a distillation system, comprising:

a first compression stage including a first impeller and a first stator, the first impeller including a first plurality of impeller blades, the first stator including a first back plate defining a first central aperture and a first cylindrical sidewall extending upwardly from the first back plate, thereby defining a first cylindrical volume, the first impeller being disposed within the first cylindrical volume of the first stator; and

a second compression stage including a second impeller and a second stator, the second impeller including a second plurality of impeller blades, each second impeller blade including a blade tip extending upwardly therefrom, the second stator including a second back plate and a second cylindrical sidewall extending upwardly from the second back plate, thereby defining a second cylindrical volume, the second impeller being disposed within the second cylindrical volume of the second stator,

wherein said blade tips of the second plurality of impeller blades extend upwardly into the first central aperture of the first stator.

21. The vapor compressor of claim 20, wherein a first height of each of the plurality of first impeller blades is greater than a second height of each of the plurality of second impeller blades, wherein the first height and the second height are measured from a top edge to a bottom edge of the first impeller blade and the second impeller blade, respectively, in a direction parallel to the longitudinal axis of the housing.

22. A vapor compressor for use with a distillation system, comprising:

a vertical shaft having a first end located in said housing and a second end outside of said housing, the shaft being rotatably driven at said second end;

at least one compression stage located in said housing, said compression stage including an impeller rotatable with the shaft; and

at least one bearing assembly located outside of said housing and supporting said shaft for rotation.

23. The vapor compressor of claim 22, further comprising:

24. The vapor compressor of claim 23, further comprising a deflector plate fixed to the axial spacing portion of the shaft between the seal and the bearing assembly, the deflector plate rotating with the shaft.

25. The vapor compressor of claim 24, wherein the deflector plate includes a plurality of blades.