LIQUID RING ROTATING CASING STEAM TURBINE AND METHOD OF USE THEREOF

Abstract

A rotating liquid ring rotating casing gas turbine (10) has at least one liquid ring rotating casing (13) having an eccentrically mounted impeller (11) adapted to rotate within a surrounding liquid ring (14) so as to form chambers (15) of successively increasing volume between adjacent vanes of the impeller. A working fluid formed by high pressure gas is injected into the impeller where the chambers are narrow via a fluid inlet (19) within a static axial bore (23) of the impeller so as to rotate the impeller and in so doing the gas expands isentropically. A fluid outlet (20) within the static axial bore of the impeller and fluidly separated from the fluid inlet allows the working fluid to escape at low pressure and low temperature.

Claims

1-24. (canceled)

25. A liquid ring rotating casing gas turbine, comprising: a casing mounted for rotation about a first axis and having an inner cylindrical surface surrounding a liquid ring that is warmer than the gas so as to inhibit condensation of the gas upon contact with said liquid ring; an impeller mounted for rotation eccentrically in said casing about a second axis parallel to and spaced from said first axis, said impeller forming a static axial bore; said impeller having a plurality of vanes spaced from each other around said core with each vane extending outwardly from said bore to a tip in a radial direction with respect to said second axis such that the vanes form multiple chambers that are directed towards and lie within said inner cylindrical surface; a gas inlet within the static axial bore of the impeller for injecting a gas at high pressure into the impeller where the chambers are narrow so as to rotate the impeller and in so doing to expand said gas essentially isentropically within a plurality of said chambers so that said gas at least partially undergoes a gas-to-liquid phase change in the impeller to convert heat to work; and a gas outlet within the static axial bore of the impeller and fluidly separated from the gas inlet for allowing the gas to escape at low pressure and low temperature without being compressed.

26. The turbine according to claim 25, including a mechanical coupling between the impeller and the casing.

27. The turbine according to claim 25, wherein said gas is adapted to condense upon direct contact with a cold liquid condenser located outside the turbine.

28. The turbine according to claim 25, wherein in use the fluid changes phase from gas to liquid without the need for compression.

29. The turbine according to claim 25, wherein the liquid ring is immiscible with water.

30. The turbine according to claim 25, wherein the liquid ring is water or oil or brine.

31. A heat engine comprising the rotating liquid ring rotating casing gas turbine according to claim 25.

32. The turbine according to claim 25, further including: a first pump coupled to a source of cold water for spraying cold water into the condenser thereby condensing the gas exiting from the fluid outlet of the turbine, a second pump coupled to a reservoir containing liquid forming the liquid ring, said second pump being configured to pump said liquid to the turbine, a third pump for pumping water to the source of cold water, and a heater coupled to an outlet of said reservoir for heating the first liquid prior to feeding to the turbine.

33. The turbine according to claim 25 which includes a condenser for condensing gas escaping from said gas outlet so as to subject the gas to a change in phase from gas to liquid at low pressure whereby the gas escaping from the gas turbine is changed to a liquid at low pressure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0033] FIG. 1 is a Temperature-Entropy diagram for the conventional Rankine cycle useful for explaining where the invention departs from conventional steam turbines;

[0034] FIG. 2 shows schematically a cross-section of a LRRC steam turbine having an external steam condenser according to a first embodiment of the invention;

[0035] FIG. 3 shows schematically a cross-section of a LRRC steam turbine having an internal steam condenser according to a first embodiment of the invention;

[0036] FIG. 4 is a block diagram of a heat engine employing the LRRC steam turbine of FIG. 1;

[0037] FIG. 5 is a block diagram of a heat engine employing the LRRC steam turbine of FIG. 3; and

[0038] FIG. 6 is a pictorial perspective view of a heat engine according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0039] In the following description of some embodiments, identical components that appear in more than one figure or that share similar functionality will be referenced by identical reference symbols.

[0040] Referring to FIG. 2, there is shown in schematic cross-section a rotating liquid ring turbine wherein an impeller 11 with radial blades 12 rotates counter-clockwise around static ducts. The impeller is enclosed by a rotating casing 13 that contains a liquid ring 14 and rotates about an axis that is parallel but eccentric to the axis of the impeller so as to form chambers 15 bounded in each case by two blades 16 and the liquid ring. A mechanical coupling such as partially meshing annular gear trains 17 and 18 may be provided between the impeller and the casing so as to rotate the impeller and the casing at a similar rate. Owing to the eccentric positioning of the impeller in the rotating casing, the chambers increase in size in the direction of rotation of the impeller.

[0041] A fluid inlet 19 is provided near where the impeller blades are closest to the internal wall of the casing where the chambers are narrow so as to be wholly immersed in the rotating liquid ring, while at the opposite end (shown toward the bottom of FIG. 2), where the impeller blades are farthest from the internal wall of the casing, there is provided a fluid outlet 20. In use, steam at high pressure is injected into the fluid inlet 19, which is connected to multiple inlet ports in the narrow chambers so as to strike the impeller blades thereby rotating the impeller, and is emitted at low pressure from the fluid outlet 20. In doing so, the steam makes contact with the liquid in the liquid ring, some of which may be ejected from the fluid outlet 20 with the condensed steam. More significantly, oil is allowed to exit via a liquid outlet 21, which is located near the impeller so as to ensure that the impeller blades are completely filled with liquid where the impeller is closest to the internal wall of the casing. The liquid outlet 21 ensures that the depth of the liquid ring does not increase thereby occupying space in the chambers 15 that must be empty so as to allow for the entry of steam. In order to ensure that the volume of liquid in the liquid ring is properly regulated, there is likewise provided a liquid inlet 22 for pumping liquid into the turbine casing 13. The liquid inlet 22 and the liquid outlet 21 allow the oil level and temperature to be controlled dynamically. The fluid inlet 19 and the fluid outlet 20 are both formed in a static axial bore 23 of the impeller 11 and are fluidly separated from each other.

[0042] At the compression zone on the right side of FIG. 2, the rotating liquid radial flow is directed towards the static axial bore 23 of the impeller where the liquid functions as a piston compressor. At the left side of FIG. 2 the radial liquid flow is from the center to the rotating casing and constitutes an expanding zone.

[0043] In a LRRC compressor such as described in US 2009/0290993, gas enters the impeller from the central duct at the lower end in proximity to the compression zone.

[0044] In contrast thereto, in the LRRC turbine 10 shown in FIG. 2, gas enters the narrow chambers of the impeller via the fluid inlet 19 and thereafter expands inside the impeller towards the turbine blades, where the chambers are large. In the process, the gas expands and undergoes a gas-to-liquid phase change and can therefore operate as the working fluid of a Rankine cycle heat engine, thus avoiding the need for a compressor as is necessary in above-mentioned US 2009/0290993. This requires that the working fluid be such as to change phase, preferably after completing its useful work, whereupon it is condensed and discharged. A suitable working fluid is steam.

[0045] FIGS. 2 and 4 depict a LRRC steam turbine 30 according to a first embodiment wherein steam is generated by a steam source 31 such as a flash evaporator and fed via the steam inlet shown as 19 in FIG. 2 to a turbine 10 of the kind described above having a rotating liquid ring formed of oil. It expands inside the impeller on its way downwards 30 towards the expanding section of the turbine. The expanded steam enters the central duct 20, which thus constitutes a fluid outlet (depicted by arrows on the right of the central ducts in FIG. 2). Oil stored in a reservoir 32 is pumped by a pump 33 to an oil heater 34 and the heated oil is injected into the liquid ring fluid inlet shown as 22 in FIG. 2. Any oil that exits from the liquid outlet 21 of the turbine is allowed to replenish the oil in the reservoir 32. Steam exiting from the fluid outlet 20 of the turbine enters an external steam condenser 35 wherein steam is introduced at high pressure into a fluid inlet thereof. A source of cold water, such as cooling tower 36, sprays cold water by means of a pump 37 into the condenser 35 thereby condensing the steam exiting from the fluid outlet 20 of the turbine. The water in the condenser becomes heated owing to the condensation of steam and is pumped back to the cooling tower 36 by a pump 38 where the heat is dissipated to the atmosphere. The condenser 35 must operate under very low pressure in order to ensure efficient condensation. In order to preserve low air pressure, any gases that enter the condenser 35 and cannot be condensed are removed by a vacuum pump 39.

[0046] In a preferred embodiment, the liquid ring is formed of a type of oil that is denser than water and immiscible therewith, and may be maintained at a higher temperature than the steam in order to avoid steam condensation on the liquid ring. Since the working fluid is completely immiscible with the oil in the liquid ring, only working fluid (e.g. condensed steam) exits from the fluid outlet 20 into the central static duct 21 in FIG. 1.

[0047] FIGS. 3 and 5 show another embodiment of a heat engine 40 where common features are designated by the same reference numerals as shown in FIG. 4 and operate in like manner. Cold water from a cooling tower 36 is pumped by a pump 41 and sprayed inside the turbine 10 via spray nozzles 42 (shown in FIG. 3), and is used as a steam condenser, thus obviating the need for an external condenser as shown in FIG. 4. The hot water is collected at the oil reservoir 32 as a mixture of water and dense oil and flows to a liquid separator 43 shown in FIG. 5 from where the oil is pumped by a pump 44 back to the turbine and hot water is pumped by a pump 45 back to the cooling tower 36 where it is cooled and returns as cold water to the cold water spray nozzles 42 in FIG. 3. Steam generated by a steam source 31 such as a flash evaporator is fed via the steam inlet shown as 19 in FIG. 3 to a turbine 10.

[0048] In this embodiment, there are three inputs to the turbine since an additional inlet is required for the cold water spray and, as noted, there is thus no need for an external condenser. There is likewise no need for an oil heater, which will in any case be heated by the steam. To the extent that the liquid in the liquid ring is cooler than the incoming working fluid, the working fluid may condense on the liquid ring. This is obviously not desirable since the working fluid in its gaseous state is what drives the impeller. On the other hand, it will be understood that as a result of condensation of the working fluid, the liquid in the liquid ring becomes heated and an equilibrium state is created that impedes further condensation. For this reason, it is believed that water may also be used as the liquid ring.

[0049] While in the embodiment described above, a heated oil ring is proposed in order to avoid condensation of the steam, this may give rise to undesirable mixing forming an oil-water emulsion which may be undesirable.

[0050] Furthermore, reverting to FIG. 2, steam enters the fluid inlet 19 at the upward left side of the turbine and heats the water ring in contact therewith. The heated liquid ring cools during the few milliseconds that it takes to rotate through 2-3 radians (approx. 180) when it approaches the lower end section of the turbine. Consequently, some of the steam is absorbed by the liquid ring and does not generate shaft work.

[0051] For these reasons it is more effective to use a desiccant liquid ring such as brine, which avoids both of these drawbacks. As before, steam enters the fluid inlet 19 and, upon encountering the liquid desiccant ring in the expanding zone, the steam condenses on the liquid interface. The diffusion of water inside the liquid brine is extremely small (approximately 10.sup.9 m.sup.2/s) and the water depth at the brine steam interface will be only several microns. Within a short time interval of only several milliseconds the liquid ring interface will face low pressure steam (at the lower end of FIG. 3) and the water at the brine liquid interface will evaporate to the exit steam. Consequently, only a small fraction of the steam will travel with the liquid ring and the bulk of the steam will expand and induce effective work.

[0052] The invention also contemplates a method for generating shaft work using the turbine as described.