Condenser with reading device and automatic ordering of the liquid level

FRENCH REPUBLIC

PATENT OF INVENTION

P. V. no. 64,287

International Classification

No. 1.482.406

F 25 j SERVICE

INTELLECTUAL INDUSTRIELLE of the

Society said: ARTHUR D. LITTLE, INC. residing in the United States-^ [...][...] ;

V ~ / [...] > v r Demanded 6 June 1966, to 14^{m h 59,} to Paris.

[...] 17 April 1967 by stopped.

(Bulletin official A property industrial, no. 21 of the 26 May 1967.)

(Patent application deposited in the United States of America 11 June 196S, under the no. 463,174, the names of mm. Arthur Holder Post Jr and Walter Henry Hogan.)

A condenser

reading device and automatic control of the

liquid level and more particularly to a device

capable of reading the level of a cryogenic liquid

in a condensing system high pressure

where a cryogenic liquid is separated from a pure gas.

The helium gas is a relatively rare gas, and it is

economically desirable in many cases

recover the gas after use for reuse

subsequent. Recovery often leaves a gas

helium contaminated with air and it becomes necessary to

to purify it again before it is supplied to

a refrigerator or liquefying apparatus.

The purification of the helium then extract

contaminants and providing a pure helium gas.

Activating purification device pre-

covere at high pressures, for example 126

to about^{140 kg/cm} 2, to improve the first

capabilities of the purification, and then to send

the purified gas directly into bottles of

high pressure gas storage.

The air, the main contaminant in a mixture

air-pressurized helium gas, condenses and is

liquefied nitrogen temperatures liquid to

a equilibrium vapour pressure

an atmosphere of about with the liquid in the

condenser. Therefore, it is appropriate and desirable

extracting a major part of air helium

contaminated by cooling and condensation

before passing it through absorbers carbon

activated charcoal for extracting the remaining portion

contaminants. By eliminating as much air that it

helium is possible prior to its introduction into

absorbers at the activated charcoal, it is

possible to reduce the load on the absorbers and

minimize reactivation of the device-

positive. The air liquefaction and condensation

are normally conducted by bringing the mixed

air-helium to exchange their non-contact heat

direct liquid nitrogen. Thus [...] -

trust and condense the air almost wholly so

as helium contains less than 1% of air. The helium gas can then be passed into a absorber system charcoal to remove residual air.

II is problematic for handling the air-helium mixture at high pressures, particularly for determining the level of the liquid air to a condenser wherein it can be observed visually, and for discharging the liquefied air from a container maintained at high pressures. The apparatus of the present invention is automatic and continuous readings the level of the liquid air condensed in the pressurized vessel, and when the level rises to a predetermined point, actuate a bleed valve for removing most of the liquid air. A small amount remains in the pressure vessel to create a seal liquid seal.

The present invention relates to:

The improved apparatus for condensing the liquid air from a high-pressure cold helium and withdrawing liquid air condensed thereby to prevent undesirable action of the liquid within the box, or transfer of liquid in the absorber layer. The embodiment of an apparatus of the type described providing a continuous indication of the level of a cryogenic liquid within the pressure vessel and for discharging the liquid when it reaches a predetermined level within the box.

The embodiment of an apparatus for safe operation that reduces the load applied to the wells activated charcoal and allows unattended continuous operation.

Other features and advantages of the present invention shall become apparent from the following description which will follow made facing the accompanying drawings and giving as illustrative, but not limiting, one embodiment of the invention. On the drawings,

Figure 1 is a schematic of the equipment [...] pressurised helium in an apparatus' type of re-helium;

Figure 2 is a view in side elevation and partially in cross section of a condenser incorporating an indicating apparatus and liquid control according to the invention;

Figure 3 is a detailed sectional view to larger scale of the lower part of the apparatus of Figure 2;

Figure 4 is a sectional view taken on the line 4-4 of Figure 3;

The figure S is a detailed view in cross-section of the middle portion of the apparatus of Figure 2;

Figure 6 is a sectional view taken on the line 6-6 of Figure S;

Figure 7 is a detailed view in cross-section of the upper part of the apparatus of Figure 2 ; and, Figure 8 is a schematic view, control circuits that perform the automatic withdrawal of the accumulated liquid when it has reached a predetermined level.

In the preferred embodiment of the invention the condenser is a pressure vessel of elongate material in which is introduced a mixture air-helium precooled, and wherein the liquid air is condensed and withdrawn. A lightweight float whose response is extremely responsive to the level of the liquid air, to move a small core through a device capable of determining the position of the core and actuating a valve in the line by which liquid may be drawn, when the latter has reached a predetermined height. Therefore, the level of the liquid is continuously sensed and controlled, and the apparatus may be operated continuously without monitoring.

Figure 1 shows a schematic drawing of a typical re-helium using a condenser according to the present invention.

On Figure 1, the condenser carries the reference 10. It is dipped in liquid nitrogen 11 held in a cradle 12 properly isolated and thermally protected. The air-helium coming from the compressor 13 is carried by the pipe 14 in the condenser. The pipeline 14 passes through a heat exchanger 15 to isolated circuits wherein the gas mixture is pre-cooled before being finally cooled by the liquid nitrogen which surrounds the conduit. Helium gas from the capacitor and containing less than 1%of air under pressures to 140 kg/ [...] 126, is then transported by the pipe 17 in a scrubber to activated charcoal 18 which, as the condenser, is immersed in liquid nitrogen. The cold purified helium is then transported by the pipe 19 in the heat exchanger 15 where it drops its negative calories at inlet gas impure and from there is conveyed to a storage device of suitable helium by means of the pipe 20.

The condenser comprising the reading device and liquid level control according to the invention is shown in and all partially in cross-section on Figure 2. To show details of the apparatus, the designs in enlarged cutting of Figures 3 to 7 are divided into three parts. Referring that Figures 3,5 and 7 when assembled to examine the integer reconstructs detailed drawing of the condenser.

On Figure 2 see that a case elongated pressure 25 is provided for use as a the main condenser housing. The housing condenser is appropriately constructed with stainless steel with a diameter of about 50 mm. Condenser However a housing of any size can be produced. It is naturally required that the casing 25 of the condenser is manufactured from a material capable of retaining a structure resistant to the temperatures of liquid nitrogen, to support the pressure of the fluids it contains. The housing condenser is naturally sealed at its two ends, and near the bottom of one of the sides there is provided a fluid inlet conduit 26 which can be fixed appropriately to the main line 14 re-system (Figure 1). A the upper end of the housing is located a pipe 27 for discharging the helium from of the helium gas. This suitably includes an adapter which makes it possible to the easily attached to the pipe 17 (Figure 1) that carries the helium to the charcoal absorbers 18. A line liquid purge 28 is located at the bottom of the housing of the main condenser 25 and includes a valve 29 actuated by a solenoid or other suitable device as is illustrated in the exposed corresponding to Figure 8.

Inside the casing 25 of the main condenser and through its top, is a guide tube 30 formed of a pressure connection piece and wherein moves from bottom to top a float 32 very light. The float is responsive to the level of the liquid air in the pressure vessel. A core tubing 33 is connected to the top of the float 32 and on the tubing core is fixed to a core (not shown in Figure 2). The core in turn moves vertically within a reading device 35 responsive to the vertical position. This reader in turn is used to actuate the solenoid opens and closes the valve 29. The end of the top of the pipe ends by a plug adapter 37.

Figures 3 and 4 are detailed sections of the lower portion of the condenser according to the invention. The fluid inlet conduit 26 enters the pressure housing 25 (by the means of seals to the pressure), and includes a portion 40 arranged vertically for directing mixture down to air supply and j [...] relied of helium gas which butts against a shield plate 41. The shield plate is to prevent the incoming gas from spilling through the discharge line or purge 28 when the latter is opened to draw the liquid air. The discharge of helium with the liquid air is undesirable because it results in unrecoverable losses He by this pathway. The pipeline section 26 which passes into the inside of the pressure vessel is carried by a float support 43 which also serves to limit the lowest position of the float 32. The liquid air 44 accumulates in the bottom of the pressure vessel while the helium diffuses through it and enters the volume 45 around the guide tube from which it exits the condenser through the pipe 27. The guide tube 30 is held in alignment by use of the spacer 47 (see Figure 4). The float 32 is sealed at the lower end with the end plate 48 to provide the necessary buoyancy. The float is made of a very thin walled tubing for that its weight is as low as possible while still retain its structural integrity. The outer wall of the float 32 is coated with a very thin layer of polytetrafluoroethylene to reduce the sliding friction and prevent binding. A slight clearance 49 (of the order of 0.6 mm on the diameter about) is reserved between the outer wall of the float 32 and the inner wall of the guide tube 30. The game is sufficient to allow a small amount of liquid surround the float.

Figure 5 is a cross section of the central part of the apparatus. In fact, it demonstrates the portion of the feature which is sensitive to the portion of the float and in the description of the part of the device in Figure 7 may also be not reporter. The length of the float 32, as shown in Figure 2 is less than the length of the guide tube and the float is attached at its upper end to a smaller element or core pipe 33 through the cover plate of the top 52 of the float 32. Between the outside wall of the core pipe 33 and the inner wall of the guide tube 30 exists an annular space 53 which communicates with the volume chamber 45 through the orifices 55 (see Figure 6).

The device, which is shown in Figures 5 and 7 is used for reading the position of the float within the condenser is a linear differential transformer, known in the prior art and available commercially. Referring that the figures 5 and 7 show a housing made of two concentric tubes 56 and 57 sealed by the bottom and top by caps 58 and 59 respectively, which are seals epoxy resin formed in situ. It is permanently mounted on the guide tube 30. Said transformer consists of primary and secondary windings wound. Conductors input 61 and 62 are connected to the primary windings 60, and output conductors 64, 65, 66 and 67 are connected to the secondary windings 63. The connections of the conductor cables with the control circuit are the subject of the description of the circuit shown in Figure 8.

A magnetic core 68 is attached to the core pipe 33 by a pin 69 which passes through the core pipe and attached to said core. The core pipe is open at the end of its top to equalize the pressure within the float with the condenser pressure, and it is mounted by means of holes drilled therein at the end of a sensitive spring 72. The upper end of the spring 72 is in turn slid through a pin 73 to which it is attached, the latter being fixed on a support plate 74. The support plate is supported in turn, on a flange machined in an adapter 76 sealingly secured in the upper end of the guide tube. The adapter is threaded and attached in a pressure-tight fashion against a plug 77 provided with a suitable screw -78. Notably, when removal of the plug 77 of the adapter, the entire assembly of the float as the core and the spring can be easily removed and reinserted of the guide tube.

Figure 8 represents a suitable circuit of the linear differential transformer connected to the apparatus. The input connectors 61 and 62 of the primary are connected to a source of suitable power supply (not shown) and a solenoid 96 is likewise connected by conductors 79 and 80 to a source of suitable power supply (not shown). The conductors 65 and 66 connected to the secondary windings of the transformer feed a common conductor 81 and a measuring apparatus 90. The conductors 64 and 67 are of the same connected by the rectifiers 84 and 85, and the capacitors 86 and 87 to the measuring instrument 90. The instrument is in turn connected by a potentiometer variable at a sensitive relay 94 which actuates the solenoid 96. Finally, a display switch 97 manually actuating the take off valve 29 (Figure 1). The core 68 by moving vertically within the transformer acts on the current intensity, and the system is adapted such that when the current reaches the relay 94 by the driver 64 to excite a winding of the relay, the latter remains excited by a magnetic latch until the current in the conductor 67 reaches the same level of energy, at that time the conductor 67 excites the other winding of the relay to overcome the force exerted by the first magnetic latch. Thus the valve 29 (fig. 2) which is operated by the solenoid 96 remains open until the core, and therefore the level of the liquid air, are lowered a predetermined point.

It is naturally possible in the frame of the present invention to use any other means, that it either electromagnetic or other, -to determine