This application is the national phase under 35 U.S.C. Å 371 of PCT International Application No. PCT/IL01/00186 which has an International filing date of Feb. 28, 2001, which designated the United States of America.
This invention relates generally to gasdynamic schemes in turbomachines such as centrifugal compressors used in heat pumps, and more particularly to compact gasdynamic arrangements for high-capacity multistage centrifugal compressors working with water vapor.
Various industrial applications, e.g. desalination, water chilling, and ice-making, require massive production of cold, i.e. cooling large quantities of air, water or other coolant. A known method of absorbing heat, when water is used as coolant, is boiling the coolant water under reduced pressure at the respective low temperature. In order to dispose of the heat contained in the evaporated water, the vapor must be brought to higher temperature and pressure by suitable thermodynamic process and finally be condensed transferring the heat to an available heat sink such as water from a cooling tower. The temperature difference between the compressed vapor and the heat sink, plus some additional temperature drop needed to drive the dynamic heat transfer, all expressed in units of the saturated water vapor at those temperatures, determine the compression ratio (CR) of the compressor powering this process.
From the viewpoint of economics, it is desirable to employ the compression process in a single-stage compressor. But when by reason of various design considerations, a single-stage compressor is impractical, it is then the practice to use two or more compressor stages in series, as disclosed in the U.S. Pat. No. 5,520,008 to Ophir et al. Implementing intercooling of the gas/vapor between stages raises the thermodynamic efficiency of the operation and lowers the consumption of mechanical power.
In the heat pump assembly described in the Ophir et al. patent, use is made of a pair of individual centrifugal compressor units, each having its own impeller shaft and a bearing house therefor, as well as its own motor to drive the shaft. In this arrangement, the two motors are placed on opposite sides of the compressor chamber.
In a multi-stage centrifugal compressor in which the stages are assembled in series, the geometries of the vapor passages must be carefully designed so as to convey in an energy-efficient manner the partially compressed vapors from the discharge zone of a preceding stage at the periphery of its impeller to the central intake port of the succeeding stage. Often, intercooling of vapors between the stages is required in order to attain optimum thermodynamic efficiences. These requirements further complicate the geometry of the vapor passages, and also enlarge the physical dimensions and cost of the heat pump assembly. This is especially true of high throughput heat pump units of large diameters.
Such machines as in U.S. Pat. No. 5,520,008 have been built and are operating well, but a more compact solution is very desirable, in order to reduce cost and facilitate installation and maintenance work in confined spaces, such as service basements and galleries of large hotels, office buildings, shopping centers, etc.
A more compact arrangement is disclosed in DE 1803958A describing a two-stage turbomachine (compressor) with intermediate heat exchangers where the impellers of the two stages are disposed coaxially opposite to each other and constitute one body. The intake duct of the turbomachine is a cylinder or conical pipe coaxial with the impellers and is disposed at the side of the first stage. The discharge flow of the first stage is conveyed by a plurality of first discharge ducts to an annular heat exchanger coaxial with the impellers, embracing the intake duct and disposed also at the side of the first stage. Then the flow makes a sharp turn by 180° into a peripheral annular channel embracing the heat exchanger and is directed to the intake port of the second stage. The discharge flow of the second stage is conveyed by a plurality of second discharge ducts to another annular coaxial heat exchanger ending with a discharge port and disposed between the intake duct and the first heat exchanger, also at the side of the first stage. This arrangement places four coaxial flows and two heat exchanger volumes at one side of the impeller group, which involves high hydraulic losses.
CH 102821 discloses a four-stage turbomachine (compressor) with two parallel shafts driven by one motor by means of a gearbox. The first and the second stage impellers are on one shaft, in opposition, while the third and the fourth stage impellers are on a second shaft. The intake duct is disposed laterally to the first shaft. The discharge duct of the first stage conveys the flow from the periphery of the first impeller to the intake of the second stage along a path approximately following the surface of a torus coaxial with the first shaft, while the discharge flow of the second stage is gathered in a space defined by the same torus and conveyed via one lateral pipe to the intake of the third stage coaxial with the second shaft. This arrangement is asymmetric and does not accommodate heat exchangers or other elements in the flow path between coaxial stages.
In view of the foregoing, the main object of the invention is to provide novel gasdynamic arrangements particularly suitable for building economically feasible, compact and efficient turbomachines such as multi-stage, high-compression, high-throughput gas or vapor centrifugal compressors for heat pumps, and a novel design of a heat pump particularly suitable for use with such compressors.
In accordance with a first aspect of the present invention there is provided a gasdynamic arrangement for a multi-stage centrifugal turbomachine having an intake duct and a discharge port, comprising:
In a particular embodiment of a two-stage compressor the gasdynamic arrangement comprises:
In accordance with a second aspect of the present invention, there is provided a gasdynamic arrangement comprising an annular condenser chamber disposed concentrically around an intake duct within a heat pump assembly.
Both aspects are aimed at the development of more compact turbomachine designs. In the implementation of the arrangement of the first aspect of the present invention in a two-stage compressor, this is achieved by the usage of a short common shaft supported by a single bearing house situated between the impellers (stages) and driven by a single motor. In the implementation of the arrangement of the second aspect of the present invention in a heat pump assembly, this is achieved by a reduction of the assembly overall length. The employment of both gasdynamic arrangements provides for a highly integrated heat pump assembly, wherein all functional components of the system with the possible exception of the driving motor—multiple compressor stages, evaporator, condenser, intercooling and mist-elimination equipment—are incorporated within a single cylindrical vessel without external ducts. The assembly is characterized by reduced gas/vapor pressure losses, thereby improving the compression ratio and enhancing heat pump economy. The cost of manufacturing this integrated heat pump assembly is considerably lower than the cost of manufacturing an assembly having the same capacity composed of separate units with interconnecting external ducts. The structured configuration of the integrated assembly greatly simplifies its erection at an operating site.
For a better understanding of the invention as well as other objects and features thereof, reference is made to the attached drawings wherein:
In accordance with a first embodiment of the present invention, a heat pump and a two-sage compressor are shown in
The vessel is divided by partition walls 12 and 13 into an evaporator chamber A, a condenser chamber B and a compressor chamber C. The evaporator chamber A is equipped with headers 15 adapted to spread entrant water or other coolant in thin “curtains” with a large surface area to promote its evaporation under partial vacuum conditions.
Evaporator chamber A opens into an intake duct 16 leading into the intake port of the compressor. The inlet of intake duct 16 is covered by a mist eliminator 19 preventing the entrance of water droplets. Intake duct 16 is coaxial with the cylindrical vessel 11, and, together with partitions 12 and 13, defines the annular condenser chamber B. In the condenser chamber B, there is a plurality of nozzles 22 mounted on the cylindrical wall of the vessel 11 and adapted to spray cooling water into the chamber.
Compressor chamber C houses the first and second stages of a centrifugal compressor, both coaxial with vessel 11. Chamber C is subdivided into two cells C1 and C2 by an intermediate partition wall 24 placed between the two compressor stages. The first stage is provided with an impeller 26 rotatable within a stationary shroud 27 and is adapted to discharge partially compressed vapor through an array of diffuser ducts 28 through partition wall 24 and cell C2 toward the intake port of the second compressor stage impeller 29. The annular cell C2 is equipped with means for intercooling or de-superheating the vapor between the two compressor stages such as water spray nozzles 31. In the flow path to the intake port of the second stage, there is provided a mist eliminator 33.
The second stage impeller 29 is rotatable within a stationary shroud 35 and is adapted to discharge compressed vapor through an array of diffuser ducts 37 and apertures in partition wall 24 into the annular cell C1 of the compressor chamber C which opens into condenser chamber B through a discharge port 38.
Impellers 26 and 29 of the first and second stages of the compressor are mounted on a common shaft 40 supported by a bearing house 42 disposed between them. Shaft 40 is coupled to the external motor 10 through a gear box 43. Thus a single motor can concurrently drive both stages of the compressor.
As indicated by arrows, water vapor generated in evaporator chamber A is drawn by a suction force produced by the compressor to the first stage intake via mist eliminator 19 and intake duct 16. The first stage impeller 26 partially compresses the vapor and discharges it to second stage intake via diffuser ducts 28 and cell C2, through mist eliminator 33. In cell C2, partially compressed vapor is de-superheated by cool water sprayed from nozzles 31 or by suitable heat exchange surfaces (not shown in
The second stage impeller 29 completes vapor compression and sends the vapor to cell C1 of compressor chamber C via diffuser ducts 37. Next, vapor enters annular condenser chamber B and is condensed there by means of cooling water sprayed from nozzles 22. The heated cooling water leaves condenser chamber B through outlet 44. The chilled water is pumped through outlet 45.
The flow path of the vapor between compressor stages is organized in a unique gasdynamic arrangement shown in
Reverting to
This configuration substantially reduces the cost of manufacturing and installing the assembly, simplifying to a significant degree the erection and maintenance of the assembly at its site of service. It also minimizes gas/vapor pressure losses, thereby improving the compression ratio and the efficiency of the assembly.
The assembly as a whole can be made even more compact by placing a suitably designed electric motor between the two impellers instead of the bearing house, the shaft line and the external motor.
Another embodiment of a heat pump assembly of the present invention is shown in
A second partition wall 54 is introduced, with apertures P1′ and P2′ similar to apertures in partition wall 24. The peripheral discharge zone of impeller 48 is connected to apertures P1′ on partition wall 54 by a crown-like array of diffuser ducts 57 similar to ducts 28. Ducts 37, from the peripheral discharge zone of second impeller 29 to apertures P2 on partition wall 24, are extended to apertures P2′ on the second partition wall 54.
A new cell C3 is defined between partition walls 24 and 54 adapted to convey compressed vapor from third stage impeller 48 via diffuser ducts 57 to the intake port of first stage impeller 26. Intercooling spray heads 61 may be accommodated in the new cell C3, in which case an intermediate partition wall 63 carrying mist eliminators 65 is introduced in the flow path, and diffuser ducts 57 are extended to intermediate partition wall 63.
From gasdynamic point of view, impellers 48, 26, and 29 should now be designated first, second, and third stage impellers, respectively. It can be readily seen from the above that more stages may be introduced in exactly the same manner downstream of intake duct 16.
While there have been shown preferred embodiments of the invention, it is to be understood that many changes may be made therein without departing from the spirit of the invention. Thus, the assembly, instead of containing within the cylindrical vessel a multi-stage centrifugal compressor, may contain in concentric relation with the vessel a single stage compressor.
Number | Date | Country | Kind |
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136921 | Jun 2000 | IL | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IL01/00186 | 2/28/2001 | WO | 00 | 9/11/2003 |
Publishing Document | Publishing Date | Country | Kind |
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WO01/98665 | 12/27/2001 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
2674404 | Wieseman | Apr 1954 | A |
2746269 | Moody | May 1956 | A |
2770106 | Moody | Nov 1956 | A |
2793506 | Moody | May 1957 | A |
3011322 | Tanzberger et al. | Dec 1961 | A |
3165905 | Ware | Jan 1965 | A |
3447335 | Wheeler et al. | Jun 1969 | A |
4125345 | Yoshinaga et al. | Nov 1978 | A |
4454720 | Leibowitz | Jun 1984 | A |
4896515 | Endou | Jan 1990 | A |
5520008 | Ophir et al. | May 1996 | A |
5857348 | Conry | Jan 1999 | A |
Number | Date | Country |
---|---|---|
102 821 | Jan 1924 | CH |
252 609 | Jan 1948 | CH |
1 803 958 | Jun 1969 | DE |
932 307 | Mar 1948 | FR |
Number | Date | Country | |
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20040050090 A1 | Mar 2004 | US |