US3092973A

US3092973A - Cryogenic apparatus

Info

Publication number: US3092973A
Authority: US
Inventors: Robert W Hughes
Original assignee: Joy Manufacturing Co
Current assignee: Joy Manufacturing Co
Priority date: 1960-12-05
Filing date: 1960-12-05
Publication date: 1963-06-11
Anticipated expiration: 1980-06-11

Description

June 1963 R. w. HUGHES 3,092,973

CRYOGENIC APPARATUS Filed Dec. 5, 1960 INVENTORZ ROBERT W. HUGHES BYXMW ATTORNEY United States Patent 3,092,973 CRYOGENIC APPARATUS Robert W. Hughes, Greensburg, Pa., assiguor to Joy Manufacturing Company, Pittsburgh, Pa., 2 corporation of Pennsylvania Filed Dec. 5, 1960, Ser. No. 73,729 2 Claims. (Cl. 62-55) This invention relates to cryogenic apparatus and more particularly to means for removing a cryogenic liquid from a vessel containing both a pressurized cryogenie liquid and vapor without permitting loss of vapor from the vessel.

As is known, cryogenic liquids such a nitrogen are produced within a suitable column which is operated under substantial pressure during the rectification process. Such processes are carried out at low temperatures such as on the order of 95 Kelvin and under such conditions slight losses of vapor from the column represent a substantial heat loss to the cryogenic system. Inasmuch as considerable energy input is required to obtain such low operating temperature it is highly desirable from an efiiciency standpoint to prevent such loss of refrigerant capacity. Accordingly, when a cryogenic liquid is desired as an end product it is desirable that the liquid be removed from the column without permitting any loss of vapor from the column. Heretofore it has been general practice to provide a valved exit line which is open to the portion of the column in which the liquid has accumulated so that the cryogenic liquid can be selectively drained from such collecting portion. Such practice has not been satisfactory as considerable vapor is also blown through the exit =line during the draining process due to the operating pressure existing within the column.

Accordingly, one object of this invention is to provide new and improved cryogenic apparatus for removing a cryogenic liquid from a pressurized cryogenic vessel.

Another object of this invention is to provide new and improved cryogenic apparatus for continuously and automatically removing cryogenic liquid from a pressurized cryogenic column.

A more specific object of this invention is to provide I a ballfloat valve operatively connected thereto in acv cordance with the principles of this invention.

Inasmuch as there are a large number of cryogenic columns of various designs for liquefying a gas, mixtures of gases, and mixtures of gases and liquids, and as the principles of this invention are applicable to all such columns, the drawing shows a single column rectification unit 2 as is commonly employed for liquefying the gaseous components of air. Although various gaseous components of air may be suitably liquefied in the rectification column 2, for the purpose of better understanding this invention the description is made with reference to the production of liquid nitrogen in a manner as is well known in the art. It will be realized that columns such as column 2 are commonly referred to as either pressure, fractionating, distillation or rectification columns and that the structure of this invention is operable with all such columns.

As is known, a suitable single column nitrogen generator such as column 2 comprises an elongated pressure vessel which is laterally enlarged at its upper end. A suitable condenser 4 is suitably located within the upper ice laterally enlarged end of the column 2 which comprises a pair of longitudinally spaced plates 6 peripherally sealed to the inner surfaces of the laterally enlarged portion of the column 2 to form a suitable chamber 8 therebetween. A suitable plurality of elongated open end tubes 10 extend through the chamber 8 and through the plates 6 which tubes 10 are peripherally sealed to the plates 6. A suitable liquid nitrogen directing means 12 is provided below the lower ends of the tubes 10. Such construction of the column 2 provides an annular ledge or shelf 7 spaced below the lower ends of the tubes 10 wherein the liquid nitrogen collects and which is commonly referred to as the nitrogen shelf.

In operation suitably compressed air is suitably supplied to the bottom of the column 2 through a suitable conduit 14 and cold liquid nitrogen refrigerant is suitably supplied ot the nitrogen shelf 7 which liquid nitrogen flows downwardly in the column 2 in countercurrent relationship with the compressed air gas stream rising from the bottom of the column 2. The boiling point of the nitrogen in the gas stream at the operating pressure of the column 2 is lower than that of the oxygen in the gas stream, therefore the oxygen in the gas stream is condensed by the descending nitrogen rain and liquid nitrogen in the bottom of the column 2, which accumulates therein during the operation of the column and this description is with reference to an operating condition rather than a starting condition, evaporates and rises to the top of the column 2. This process results in a nitrogen gas of high purity and a mixture of oxygen enriched liquid air at the bottom of the column 2. The liquid oxygen-air mixture at the bottom of the column 2 is suitably withdrawn through a suitable conduit 16 and through suitable controls, not shown, flows into the boiler condenser 4 at the top of the column 2 through a suitable conduit 18. In operation the pressure of the withdrawn oxygen-air mixture is reduced so as to produce a cold flow through the boiler condenser 4 which flow is discharge from the boiler condenser 4 as eflduent gas through a suitable discharge line 19. By providing the cold boiler condenser 4- the rising nitrogen gas of the supplied air mixture is suitably reduced in temperature so as to con dense and produce liquid nitrogen within the tubes 10 which liquid nitrogen drains gravitationally to the nitrogen shelf 7.

In the operation of the column 2 the incoming air mixture is supplied at a suitable pressure to obtain the, above described operation, such as 5 atmospheres pressure, so that the liquid nitrogen accumulating on the shelf 7 is at the pressure Within the column 2. In accordance with this invention such liquid nitrogen is removable as'a product of the column 2 continuously and automatically without loss of vapor pressure in the column 2 by means of a suitable .ball float valve 20 having-a suitable housing 22 formed to provide a suitable collecting chamber 24. The chamber 24 is suitably connected by means of a suitable conduit 26 to the column 2 at the nitrogen shelf 7 so that the liquid nitrogen on the shelf 7 can flow gravitationally from the nitrogen shelf 7 through the conduit 26 into the chamber 24. With the operating pressure required a certain volume of vapor of the mixture within the column 2 also flows into the chamber 24- with the liquid nitrogen accumulating at the bottom of the chamber 24 and the vapor accumulated thereabove. Thus, the liquid nitrogen 25 in the chamber 24 is at the same pressure and temperature as the column 2. Inasmuch as the production of liquid nitrogen by such a column 2 is a continuous process it will be realized that the liquid nitrogen continuously flows from the nitrogen shelf 7 through the conduit 26 into the chamber 24, accordingly, the conduit 26 is of sufficient cross sectional area to permit also the vapor within the chamber 24 to be in constant communication with the interior of the column 2 including the periods of maximum liquid nitrogen flow through the conduit 26. Thus, over a period of time a substantial quantity of liquid nitrogen 25 will accumulate withinthe chamber 24 so that the liquid level of the nitrogen 25 in the chamber 24 will be constantly rising.

The housing 22 is also provided with a suitable rigid support 28 extending inwardly of the chamber 24 to which a suitable rigid arm 30 is suitably pivotally connected. The arm '30 supports a suitable ball 32 spaced from the pivot connection thereof and. additionally supports an integral plunger 34 intermediate the pivot connection and the ball 32 which is arcuatelymovable around the pivot connection of the arm 39 with the arm 30 as the ball 32 rises and falls within the chamber 24 as the liquid level of the liquid nitrogen changes within the chamber 24. The housing 22 is also provided with a suitable passageway 36 extending from the interior of the housing 22 from the chamber 24 in alignment with the plunger 34 to the exterior of the housing 22 with the outer end of the passageway 36 being suitably connected to a suitable discharge conduit 38 to permit the removal of liquid nitrogen 25. If desired, a suitable manual control 'valve 40 may be placed in the conduit 38 for control purposes such as when removing and positioning containers for receiving the liquid nitrogen 25 from the conduit 36. The ball float valve 20 as shown operates in the conventional manner in that the ball 32 floats upwardly as the liquid nitrogen 25 accumulates in the chamber 24 until the liquid nitrogen 25- increases to a levelso' that when the ball 32 is moved upwardly a sufiicient distance to lift the plunger 34 away from engagement with the inner end of the passageway 36, the passageway 36 is connected to the conduit 38. As'the liquid nitrogen flows through the passageway 36 and (the conduit 38 the'ball 32 descends with the liquid nitrogen 25 as the level of the liquid nitrogen 25 descends to lower the free end of the plunger 34 into engagement with the inner end of the passageway 36 to stop the flow of the liquid nitrogen 25- from the chamber 24. By proper positioning of the ball 32 with reference to the chamber 24 the ball 32 descends to cause the passageway 36 to close before the liquid level of the nitrogen 25 descends to the level of the inner end of the passageway 36. Thus, a'liquid nitrogen seal is provided between the vapor in the upper part of the chamber 24 and the passageway 36 at all times to prevent any loss of vapor.

Inasmuch as the principles of ball float valves are well known, the valve 20 maybe of any desired construction to obtain the above desired operation. For the purposes of this invention the arm 30 is pivotally connected to the support 28 at one end so that the arm 30 moves through a given arcuate path with reference to the housuse for transferring a cryogenic fluid from a high pressure 1. A cryogenic apparatus comprising, a cryogenic column being thermally operable to remove energy from a selected gaseous constituent and form a liquid product of such constituent, means in said column for accumulating such liquid product, said column being operable within a range of pressures and temperatures which continually causes a portion of such liquid product to return to such gaseous state, a chamber, conduit means connecting said chamber with said accumulating means, said chamber being located so that such liquid product gravirationally flows through said conduit to said chamber, said conduit being of sufiicient cross sectional area to accommodate flow of such liquid product from said accumulating means to said chamber and to accommodate flow of such liquid product in a gaseous phase from said chamber to said accumulating means, and control means in said chamber responsive to the level of such liquid product for permitting flow of such liquid product from said chamber to a remote location.

2. A cryogenic apparatus comprising, a cryogenic column being thermally operable to remove energy from 'a selected gaseous constitutent and form a liquid product of such constituent, means in said column for accumulating such liquid product, said column being operable within a range of pressures and temperatures which continually cause a portion of such liquid product to return to such gaseous state, a chamber being located at a lower level than said accumulating means, conduit means connecting said chamber with said accumulating means for permitting gravitational flow of such liquid product to said chamber, said conduit means being operative to maintain substantially the same pressure and temperature in said chamber as in said column thus causing evaporation of a portion of such liquid product in said chamber, said conduit means being of sufficient cross sectional area to accommodate flow of such liquid product from said accumulating means to said chamber and to accommodate flow of such liquid product in a gaseous phase from said chamber to said accumulating means, and control means in said chamber responsive to the level .of such liquid product in said chamber for permitting flow of such liquid product from said chamber to a remote location.

References Cited in the file of this patent UNITED STATES PATENTS 2,041,725 Podbielniak May 26, 1936 2,198,142 Wade Apr. 23, 1940 2,346,253 De Motte Apr. 11, 1944 2,896,415- Shanley July 28, 1959 2,941,376 Messerli June 21, 1960

Claims

1. A CRYOGENIC APPARATUS COMPRISING, A CRYONGENIC COLUMN BEING THERMALLY OPERABLE TO REMOVE ENERGY FROM A SELECTED GSSEOUS CONSTITUENT AND FORM A LIQUID PRODUCT OF SUCH CONSTITUENT, MEANS IN SAID COLUMN FOR ACCUMULATING SUCH LIQUID PRODUCT, SAID COLUMN BEING OPERABLE WITHIN A RANGE OF PRESSURES AND TEMPERATURES WHICH CONTINUALLY CAUSES A PORTION OF SUCH LIQUID PRODUCT TO RETURN TO SUCH GASEOUS STATE, A CHAMBER, CONDUIT MEANS CONNECTING SAID CHAMBER WITH SAID ACCUMULATING MEANS, SAID CHAMBER BEING LOCATED SO THAT SUCH LIQUID PRODUCT GRAVITATIONALLY FLOWS THROUGH SAID CONDUIT TO SAID CHAMBER,