US2204169A - Turbine for the expansion of gas to produce refrigeration - Google Patents

Description

June 11, 1940. s. ZERKOWITZ 2,204,169

TURBINE FOR THE EXPANSION 01? GAS TO PRODUCE REFRIGERATION Filed Feb. 15, 1938 2 Sheets-Sheet 1 INVENTOR GUiDO ZERKOW ITZ ATTORNEY June 11, 1940. e. zERKown'z TURBINE FOR THE EXPANSION 01' GAS TO PRODUCE REFRIGERATION Filed Feb. 15, 1938 2 Sheets-Sheet 2 FIG-3.

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\NVENTQR GU I DO ZERKOW 1 T2 ATTORNEY Patented June '11, 1910 PATENT" OFFICE TURBINE non THE EXPANSION or GAS T raonuos nsr-mosas'rron Guido zd-rowm, 'Trieste, Italy, alsignor to Geaellschai't fiir Lindes Eismalchinen A. 6.,

Hollriegelskreuth, near Munich,- Germany Application February 15, 1938, Serial No. 190,508

In Germany February 27, 1987 16 Claims.

I This invention relates to a turbine for the expension of gas to produce refrigeration, and more particularly to an improved turbine for expanding compressed gases at low temperatures in the process of separating gas mixtures by fractional condensation or distillation at low temperature.

This application is an improvement on the apparatus disclosed and claimed in my co-pending application Serial No. 69,543, filed March 18, 1936, now issued as Patent No. 2,165,994.

In said copending application, a high speed expansion turbine is described which consists of one or only a few stages, and which has a rotor of small diameter. turbine is overhung so that the shaft on which the rotor is mounted extends toward one side side of the housing of the turbine. The housing or shell of the turbine is supported by the housing of the driven machine or reduction gear in such manner that the metallic path for the conductlon of heat from the rotor is a minimum. It is also pointed out in the copending application that in order to obtain a desired reduction of temperature by expansion, it is not sufllcient that the turbine have a good efllciency in the customary sense. The customary efiiciency, including the mechanical losses, is onlyof minor importance in the separation of air, for a high internal efllciency alone is not sufllcient in the present case because, as can be readily seen by reference to an entropy diagram, the internal work of a turbine running at low temperatures is increased by heat supplied by the environment, although the final temperature of the expansion is thereby increased. This effect, however, must be avoided in the'present case when producing refrigeration, for not only a high internal efficiency of the turbine but also a perfect thermal insulation must be provided, and since the heat drop which is available is generally small, the losses in the inlet and outlet pipes become very important.

It is a principal object of the present invention to provide a turbine having an increased emciency for the production of refrigeration by the expansion 01' gases. Another object of the invention is to provide a turbine of the class described in said copending application, which is arranged to recover a substantial amount of the energy of the gases flowing from the blades of the rotor. The above and other objects and the novel features of the invention will be apparent from the following description taken in connection with the drawings in which:

The rotor of the expansion I vFig. 1 is a sectional view showing a form of the apparatus applied to a radial flow turbine according to the present invention;

Fig. 2 is a longitudinal sectional view of another form of the apparatus applied to an axial flow turbine according to theinvention;

' Fig. 3 is a fragmentary sectional view of an altternate construction of the outlet connection of either form of turbine;

Fig. 4 is a similar view of another form of outlet connection;

Fig. 5 is a fragmentary sectional. view of an alternative arrangement of the outlet diffuser of either turbine; and I Fig. 6 is a right sectional view taken on the i8 line 8-8 of Fig. 5. I

The present invention makes possible an increase ln'the efllclency of a gas or air turbine for the production of low temperatures by providing a diffuser on the discharge side of the rotor blades. According to the invention, the flow energy of .discharge is recovered by providing a diffuser after the rotor which consists of a passage limited by two stationary coaxial surfaces of revolution between which the driving medium flows. The as sheet metal casing which forms the inner surface of revolution tapers out approximately to a point and extends preferably over a portion only of the length of the diffuser in such a manner that, in flowing through the diffuser, the so driving fluid is addltionallyconducted through the passage formed by the outer surface of rev-v olution alone. By this means there is effected a favorable conversion of energy from the standpoint of flow technique both in the diffuser it- '35 self as well as when discharging from the dif-- fuser into the adjacent piping. The diffuser is arranged adjacent the opposite side of the rotor with ,respect to the bearings. Therefore, it is not necessary to limit its length, audit is possible 40 to select. the most favorable ratio of cross. sectional increase of the passage according to the laws of fluid flow. The ratio of expansion based upon a unit length is preferably selected to correspond to an orifice angle of from four to twelve degrees. The velocity of the driving fluid when discharging from the diffuser can thus be kept as low as desired and, with low heat losses, can be reduced to five to ten meters per second. Through this arrangement, an appreciable por- 59 tion of the velocity energy is recovered when discharging from the rotor.

Diffusers constructed according to the presen invention are suitable for radialiiow turbines as 7 well as for axial flow. turbines as illustrated in .5;

' radial intermediate dividing walls into individual Figs. 1 and 2. When, in radial flow turbines, the flow through the rotor is from the outside toward the axis, which arrangement is especially advantageous for nozzle control, the diffuser also serves for simultaneously redirecting the radial flow into an axial flow. To this end the part of the diffuser channel which simultaneously serves for redirecting the flow is preferably constructed with a smaller orifice angle than the subsequent axial portion in which energy conversion only occurs. The inner casing of the diffuser may be constructed of relatively thin sheet copper, brass, or similar material. However, even the outer casing surface can have a relatively thin wall thickness in most cases because the final or discharge pressure of turbines used to produce refrigeration is, as a rule, only slightly higher than the atmospheric pressure. Therefore, despite a great ratio of expansion, neither the weight nor the heat capacity of the turbine is appreciably increased.

Since the turbine may comprise a single stage while the impact must be made variable, as by varying the number of nozzles in operation, the diffusing chamber according to the invention is preferably subdivided by means of practically passages, each of which corresponds to a group of nozzles. These dividing walls extend along the.

entire length of the diffuser and separate it into several individual passages, each of which may preferably be closed of! individually by means of a shut-oil valve. The number of shut-of! valves, which are preferably located near the discharge end of the diffuser, is arranged to correspond to the number of sets of nozzles or to the supply or regulating valves at the entrance to the turbine.

While the discharge tubes of certain turbines for compressible driving fluids have been constructed in the form of diffusers, such diffusers have a poor ,efliciency due to the fact that a favorable conversion of the velocity energy into pressure energy was impossible because of repeated and irregular redirection of the driving fluid.

Referring now to the drawings and particularly to Fig. 1, a radial flow turbine is shown similar to that shown in Fig. 2 of the copending application previously referred to and described therein. At III is shown the driven device for absorbing or utilizing the power. The turbine casing H is supported upon the housing of device Ill. The hollow shaft I! of the turbine passes through the right side wall of the housing II and is journalled in bearings mounted within the housing ID. The turbine rotor i3 is secured at the left end of the shaft 12. The driving fluid, coming for example from an air separation apparatus indicated at l4 and which is not further illustrated in the interests of clearness, is conducted to the turbine nozzles 30 through the connection IS. The nozzles 30 project the fluid against a ring of blades l6 mounted on the rotor adjacent its rim. The blades l6 project to the left and are disposed parallel to the axis of the rotor, and the fluid flows radially inwardly across the blades leaving them in a radial direction. The diffuser of the present invention consists of an external casingwall l1 and a coaxial internal casing wall I or surface lb. The diffuser, in this embodiment of the invention, fulfills both the task of redirecting the radial flow into an axial flow as well as converting the discharge energy of the driving medium leaving the rotor into pressure energy to the greatest possible extent. Both outer casing wall H and inner casing wall i8 comprise surfaces of revolution symmetrical about the axis of the rotor ii. The inner casing wall it is of conoidal shape and has its base portion adjacent to, but not touching the rotor i3. The wall {8 of the casing has the form of a surface of revolution generated by a curved element revolved about the axis of the rotor and terminating in substantially a point which is substantially on said axis. The casing wall i8 does not extend throughout the entire length of the diffuser. The free-flow cross-section of the diffuser passage is so constructed that the major portion of the energy conversion occurs in the second axial flow portion 32 of the diffuser to the left of the inner surface l8 while the first portion 3! of the passage enclosed between the surface i8 and the outer casing wall I7 is constructed to correspond to a smaller orifice angle and therefore serves mainly for redirecting the driving medium.

In Fig. 2 is shown a form of the diffuser according to the invention applied to an axial flow turbine. In this embodiment also the diffuser is formed by outer and inner casing surfaces of revolution 41 and 48 respectively. The rotor 43 is mounted adjacent the end of shaft 42 and has radially extending blades 4i secured to its rim. The blades 46 are impacted by the driving fluid projected to the left by the nozzles 90 which are held by the turbine housing 4| adjacent the right hand edges of the blades 46. The housing 4| is also provided with a manifold 49 which supplies the driving fluid to each of the nozzles 50. The fluid is conducted to manifold 49 by the conduit l5. In this embodiment, the inner surface 48 of the diffuser is conical and has a base which substantially covers the left face of the rotor 43. The outer casing wall 41 is also conical in shape terminating with a discharge end 52 of smaller diameter and has an included angle between its generating elements smaller than the corresponding angle of the inner surface 48 so that a desired rate of expansion is obtained. The inner surface tapers to substantially a point and extends to the left for a substantial portion of the length of the diffuser.

In this form of diffuser the major portion of the energy conversion .takes place in the portion 5| included between the surfaces 41 and 44.

piping of the gas separation apparatus. In order that the corrugations thereof will not produce flow losses, there is inserted in the corrugated tube I! a straight smooth lining tube 20 of thin metal which is secured to the casing at one end will complete a gas-tight connection with the turbine housing. In such construction the diffuser wall I! is slidably supported at its discharge end.

In cases where the turbine of either type consists of a single pressure stage only and where the impact is variable or the number of nozzles in use is varied, the diffuser may be modified as shown in Figs. 5 and 6. In this case the diffuser is divided up into several passages by means of intermediate dividing walls 22 which are radially disposed and preferably extend the full length of'the diffuser. Therefore, with partial impact or when less than the full number of nozzles is in operation, the fluid does, not flow through that passage formed by the dividing walls 12 which corresponds to the group of nozzles that are not in operation. Shut-off valves 23 are pref erably provided in each passage in order to close off the passages not in use. The valves 23, as shown, may be of the plate .or butterfly type and be arranged to rotate on radially disposed axes. Thestems 25 of the valves 23 extend radially through the external casing l1 and have handwheels 24 mounted thereon. These shut-off valves are preferably located near the discharge end of the diffuser.

I claim: 1

1. In a turbine for expanding compressed gas at,relatively low temperature to produce refrigeration, said; turbine having a rotor, a discharge diffuser comprising two stationary surfaces of revolution disposed on the discharge side of the rotor, said surfaces forming inner and outer walls of a discharge passage, said inner wall surface tapering to substantially a point located within the diffuser and extending throughout a portion only of the length of the diffuser.

2. Apparatus according to claim 1, in which the rotor of the turbine is overhung and the diffuser is arranged adjacent the side of the rotor opposite the shaft bearings.

3. A turbine for expanding compressed gas at relatively low temperature to produce refrigeration comprising a rotor of small diameter adapted for expanding the gas in a single stage at high velocity of the rotor, ahousing for said rotor, a shaft for said rotor carried in bearings. spaced from said rotor and mounted outside the housing of the rotor on one side only of the rotor; and passage means on the opposite'side of said rotor constructed and arranged for converting the kinetic energy of flow of the gas discharged from the rotor into pressure energy.

' 4. A turbine for expanding compressed gas at relatively low temperature to produce refrigeration comprising an overhung rotor of small diameter and adapted. for expanding the gas in radial stages at high velocity of the rotor, a housing for said rotor, a shaft for said rotor carried in bearings spaced from said rotor and mounted at one side of the rotor and outside of the housing of the turbine; and passage means adjacent the side of the rotor opposite the shaft bearing constructed and arranged for converting the kinetic energy of flow of'the gas discharged from the rotor into pressure energy.

5. A turbine for expanding compressed gas at relatively low temperature to produce refrigeration comprising an overhung rotor of small diameter provided with blades and adapted for expanding the gas in a single stage at high velocity of the rotor; a housing for said rotor; a shaft for said rotor carried in bearings spaced from said rotor and mounted outside the housing of the turbine; and a diifuser disposed adjacent said rotor adjacent the side opposite the shaft bearing to receive gas discharged from the blades of the rotor, said difluser comprising a discharge passage having walls arranged to provide an expansion of gas at a rate that effects the desired conversion of the energy of flow into pressure energy. 4

,6. A turbine for expanding compressed gas at relatively low temperature to produce refrigeration comprising an overhung rotor of small diameter adapted for expanding the gas in radial flow stages at high velocity of the rotor; a housing for said rotor; a shaft for said rotor carried in a bearing spaced from said rotor and mounted outside the housing of the turbine; and dis! charge means adjacent the side of the rotor opposite the shaft bearing for redirecting the radial flow of the gas into axial flow and for converting the energy of flow of the gas discharged from the rotor into pressure energy. q -7. In apparatus including a turbine for expanding compressed gas at relatively low temperatures to produce refrigeration for delivery to cold gas receiving means, said turbine having a rotor provided with blades, a discharge diffuser disposed adjacent the discharge side of the rotor to receive and conduct gas discharged from the rotor blades, said diffuser having inner and outer casing walls, said inner casing wall extending throughout a portion only of the length of the diffuser and tapering to substantially a point within the passage formed by the outer casing wall, and means for effecting a gas-tight connection between said turbine and the cold gas receiving means while 8. In apparatus including a turbine for expand ing compressed gas at relatively low temperatures to produce refrigeration, said turbine having a rotor provided with blades, a discharge diffuser disposed adjacent the discharge side of the rotor to receive and conduct gas discharged from the rotor blades, said diffuser having inner and outer casing walls, said inner casing wall extending. throughout a portion only of the length of the diffuser and tapering to substantially'a point within the passage formed by the outer casing wall, and an expansion joint adjacent the discharge end of said diffuser, said joint comprising a corrugatedgas-tight outer sleeve and a smooth thin-walled lining secured at one end only thereof to the casing.

9. In apparatus including a turbine for ex panding compressed gas at relatively low temperatures to produce refrigeration for delivery to cold gas receiving means, said turbine having a housing and a rotor'providedwith blades therein, a discharge diffuser disposed adjacent the discharge side of the rotor to receive and conduct gas discharged from the rotor blades, said diffuser having inner and outer casing walls, said inner casing wall extending through a portion only of the the length of the diffuser and tapering to subdiffuser being freely slidable to the corrugated tube.

10. In apparatus including a turbine for expanding compressed gas at relatively low temperatures to produce refrigeration, said turbine comprising gas inlet nozzles, and a rotor having blades opposite said nozzles, a discharge diffuser disposed adjacent the discharge side of the rotor to receive and conduct gas discharged from the blades thereof, said diffuser having inner-and outer casing walls, said inner casing wall extending through a portion only of the length of the diffuser and tapering to substantially a point within the passage formed by the outer casing wall, and radial partitions disposed in said diffuser for dividing said diffuser lengthwise into a plurality of passages, each of said passages being arranged to conduct gas discharged from a group of nozzles of the turbine.

11. In apparatus including a turbine for expanding compressed gas at relatively-low temperatures to produce refrigeration, said turbine comprising gas inlet nozzles, and a rotor having blades opposite said nozzles, a discharge diffuser disposed adjacent the discharge side of the rotor to receive and conduct gas discharged from axially relatively the blades thereof, said diffuser having inner and outer casing walls, said inner casing wall extending through a portion only of the length of the diffuser and tapering to substantially a point within the passage formed by the outer casing wall, radial partitions disposed in said diffuser for dividing said diffuser lengthwise into a plurality of passages, each passage conducting gas discharged from a group of nozzles of the tur-" bine; and stop valves disposed in said passages adjacent the discharge end of the diffuser whereby the passage corresponding to a group of noz-. zles not in use may be closed off.

12. In apparatus including a turbine for expending compressed gas at relatively low temperatures to produce refrigeration, said turbine having a rotor provided with blades; a discharge diffuser disposed on the discharge side of the rotor to receive and conduct gas discharged from the blades thereof, said diffuser having inner and outer casing walls, said inner casing wall extending through a portion only of the length of the diffuser and tapering to substantially a 13. A turbine for expanding compressed gas at relatively low temperature to produce refrigeration comprising an overhung rotor of small diameter adapted for expanding the gas in a sin-- gle stage at high velocity of the rotor; a housing for said rotor; a shaft for saidrotor carried in bearings spaced from said rotor and mounted outside the housing .of the turbine, said shaft extending toward one side of the rotor; and a discharge difluser disposed adjacent the opposite side of the rotor from that toward which the shaft extends, said diffuser comprising two stationary coaxial surfaces of revolution forming inner and outer walls of a discharge passage, and said inner wall surface tapering to substantially a point located within the diffuser.

14. A turbine for expanding compressed gas at 5 relatively low temperature to produce refrigeration comprising nozzles arranged in groups; an overhung rotor of small diameter, said rotor being provided with blades opposite said nozzle .adapted for expanding the gas in a single pressure stageat high velocity of the rotor; a housing for said rotor; a shaft for said rotor carried in bearings spaced from said rotor and mounted outside the housing of the rotor, said shaft extending toward one side of the rotor; a diffuser disposed adjacent the side of the rotor opposite to the side toward which the shaft extends, said diffuser comprising two stationary coaxial surfaces of revolution forming inner and outer walls of a discharge passage, and said inner wall surface tapering to substantially a point within the diffuser; radial partitions disposed in said diffuser for dividing said. diffuser lengthwise into a pluralty of passages, each of which conducts gas discharged from a group of nozzles of the turbine; and shut-off valves disposed in said passages adjacent the discharge end of the diffuser.

15. A turbine for expanding compressed gas at relatively low temperature to produce. refrigeration comprising nozzles arranged in groups; an overhung rotor of small diameter, said rotor being provided with blades opposite said nozzle adapted for expanding the gas in radial stages at high velocity of the rotor, a housing for said rotor; a shaft for said rotor carried in bearings spaced from said rotor and mounted outside the housing of the turbine, said-shaft and bearings being disposed at one side of the rotor; a diffuser disposed adjacent the opposite side of the rotor, said difluser having inner and outer walls forming a discharge passage, said inner wall surface tapering to substantially a point located within the difluser; radial partitions disposed in said diffuser for dividing said diffuser lengthwise into a plurality of passages; each passage conducting gas discharged from a group of nozzles of the turbine; and means for connecting a discharge conduit to said turbine to receive the gas discharged therethrough, such means being arranged to allow expansion and contraction of said diffuser. 5

16. A turbine for expanding compressed gas at relatively low temperature to produce refrigeration comprising an overhung rotor of small diameter adapted for expanding the gas in a single stage at high velocity of the rotor; a housing for said rotor; a shaft for said rotor carried in bearings spaced from said rotor and mounted outside 1 the housing of the turbine, said shaft extending toward one side of the rotor; and a discharge diffuser disposed adjacent the opposite side of the rotor from that toward which the shaft extends; said diffuser comprising two stationary coaxial surfaces of revolution forming inner and outer walls of a discharge passage; said inner wall surface tapering to substantially a point located 55 within the diffuser, and the axis of rotation of said surfaces of revolution being in alignment with the axis of said rotor.

GUIDO ZERKOWITZ'.

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