US2046284A

US2046284A - Apparatus for producing oxygen of high purity

Info

Publication number: US2046284A
Application number: US740902A
Authority: US
Inventors: George J Boshkoff
Original assignee: Union Carbide and Carbon Corp
Current assignee: Union Carbide Corp
Priority date: 1933-05-18
Filing date: 1934-08-22
Publication date: 1936-06-30
Anticipated expiration: 1953-06-30

Description

June 30, 1936. a. J. BOSHKOFF 2,046,284

APPARATUS FOR PRODUCING OXYGEN OF HIGH PURIfIY Original Filed May 18, 1933 2 Sheets-Sheet 1 INVENTOR June 30, 1936. G. J. BOSHKOFF 2,046,284

APPARATUS FOR PRODUCING OXYGEN OF HIGH PURITY Original Filed May 18, 1935 2 Sheets-Sheet 2 INVENTOR Patented June 30, 1936 HIGH PURITY George J. Boshkofi, Buflalo, N. Y., assignor, by

mesne assignments, to Union Carbide and Carbon Corporation, a corporation of New York Original application May 18, 1933, Serial No.

671,690, now Patent No. 1,985,763, dated December 25, 1934.

Divided and this application August 22, 1934, Serial No. 740,902

5 Claims.

This invention relates to apparatus for producing oxygen of high purity and more particularly oxygen in the liquid phase free from high boiling point materials.

The invention has for its object generally, the provision of improved apparatus whereby oxygen, especially liquid oxygen, may be readily produced in an easy and expeditious manner with rectifying apparatus, whether operated continuously or discontinuously, so as to be substantially free from impurities of the character indicated.

More specifically, it is an object to provide apparatus for the manufacture of oxygen whereby it is produced substantially free from small amounts of hydrocarbons and rare gases ordinarily present in the incoming air, which is employed as the raw material from which the oxygen is to be separated.

It is also an object to provide gas separating apparatus with rectification chambers or columns so arranged that substantially pure oxygen is separated by fractional condensation and evaporation without contamination with undesired high boiling point materials and without interfering with the stability and operative balance in the cyclic operations taking place in the rectification columns or chambers.

It is also an object to provide an additional column or chamber in rectification apparatus which is to be operated in conjunction with the usual second or last chamber of ordinary twocolumn apparatus.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements,-

and arrangement of parts, which will be exemplified in the construction hereinafter set forth and the scope of the application of which-will be indicated in theclaims.

This application is'a division of my application Serial No. 671,690, filed May 18, 1933, issued as Patent No. 1,985,763, granted December 25, 1934.

For a fuller understanding of the nature and objects of the invention references should be had to the following detailed description taken in connection with the accompanying drawings, in which:

Fig. 1 is a fragmentary vertical sectional view showing somewhat diagrammatically a rectification apparatus constructed in accordance with the invention; and

Fig. 2 is a similar view showing a modified arrangement in which the added column, provided in accordance with the invention, is operated separately.

In the manufacture of oxygen for industrial use, it is customary to employ air as the raw material and to separate the oxygen from the air in one or more stages by the rectification of liquid air, the atmospheric air having been compressed and cooled by heat exchangers and expaneled in various stages by steps well known to the art. There are in air, as is well known, certain gas materials of high boiling point which frequently comprise undesirable impurities in oxygen obtained in this manner. Also, where oxygen is to be provided for industrial use, very small amounts of certain hydrocarbons and other 15 undesirable gases may be present as impurities. By the present invention, these relatively high boiling point materials are separated from the liquid oxygen by steps which do not require the input of any more power than is now customarily employed in the operation of the usual rectification cycle.

In the practice of the present invention, the step of rectifying the gaseous mixture in the low pressure rectifying column or chamber is per-' formed in two stages carried out successively. This is advantageously achieved by dividing the low pressure rectifying chamber or column into two parts and operating them in series. This division preferably afiects what would ordinarily be the lower two-thirds of the low pressure rectiiying column of a two-column rectifying apparatus.

Referring now to the drawings and particularly to Fig. 1, l denotes generally the high pressure column or chamber of a rectifying apparatus into which the gaseous mixture to be separated is introduced in a cooled state through the conduit II, the cooling being carried outin any well-known manner, for example, by means of expansion or passage through heat interchangers, or both. This column is also provided with suitable dephlegmating means, for example, perforated partitions l2. The lower end l3 of this column serves as a kettle in which liquid collects and boils, the more volatile products passing upwardly in the column. From this kettle the conduit l4 leads to a distributing head l5 disposed in the upper portion of a low pressure chamber or column l6 preferably disposed above the high pressure chamber .lll. In the lower end of this second chamber is disposed a condenser H which serves to receive the volatile material arising from the chamber in, a substantial portion thereof being condensed and returned to municatesatitslowerendwiththechamberll just above the shelf. The chamber II is also provided with dephlegmating means, here shown aspartitions 2l,similartothoseinchambers ill and it.

In order to vaporiae the liquid which collects inthelowerendoi'chamberilinamannersimilar to that in chamber It, a heating coil is provided in this chamber and the uncondensed gaseous material led oil by the conduit ll supplied thereto through a branch connection II. The liquid obtained by conderkation in coil is supplied by another conduit 26 to the distributing head 2!. Gaseous material, which is substantiallypure oxygen, is led oil. from the chamber I to chamber II through conduit 21, this conduit being provided with a branch 21" for bleeding of! gaseous material when desired.

It is also desirable to transfer gas material from the upper portion of chamber l 6 to an intermediate point in chamber 28. A conduit for eiIecting this is shown at 2'l'.- The uncondensable gas materials which have a very low boiling point, together with the maJor portion of the nitrogen, are preferably led oil. the top. of the chamber 20 by means of a conduit here indicated at 28.."

In operation, when the gaseous mixture supplied to the chamber ll through the conduit II is cooled compressed atmospheric air, liquid collects in the kettle I; which becomes relatively rich in oxygen, since the more volatile constituents, such as nitrogen, are being continually boiled oil! and washed, the condensate being returned by counter washing or refluxing. The

oxygen content of the liquid which collects inthe kettle i3 becomes relatively high, for example,from35to45percent. Whileitisseen that the more volatile constituents, that is, the low boiling point constituents, are continually 're-h moved. the high boiling point constituents which include undesired impurities remain and are passed into the low presure chamber it by way of conduit It with the liquid transfu'red.

In the chamber it, the liquefied gas material of high oxygen content collects in the lower end and is heated,.whereby further volatile constituentsareremoved; Aliquidofveryhighbxygen content, in results,,but still includes the high boiling point impurities. The oxygen portion is here vaporized without carrying oil! anyofthehlahbdlingpointimpurities,

Byoperatingthechamberllinserieswiththes chamber lt,agaseousmaterialcomprisingsub-- stantiallypureoxygenfreefromhighboiling point impurities is withdrawn throuah the conduit 21 and is by counter-current Theupper chamber 36 also has dephlegmating washing, so as to collect about the coil II, substantially all the remaining volatile or low boiling point'material being removed and withdrawn through the connection II. Gaseous material is also conducted by conduit II from the upperportion oi. chamber it to a point near the upper portion oi chamber 20; theoxygen content thereoi, however, is substantially lower than the oxygen content oi the liquid introduced into chamber." through conduit It. In consequence, substantially pure liquid oxygen may be withdrawn fromthe lower portion of this chamber through V the withdrawal connection 21. A withdrawal connection *2! is advantageously. provided for the lower end of chamber it in order tocarry l away when desired the high boiling point impur- 'ities which may collect.

In Fig. 2, a modiiled arrangement of apparatus for carrying out the procms oi the present invention is shown in which the divided low pressure chambers that are operated in series are showna's structurally separated. Here, a high pressure column or chamber is shown at 3|, to which a cooled, compressed, gaseous mixture. is supplied through a conduit 8|. This chamber 35 has dephlegmating means 82 and a kettle II at the lower end, from-which liquid comprising a concentrate ofoxygen is withdrawn through a conduit 34 and supplied to a distributing head in a low pressure chamber or upper column '36 of atwo-column rectifying apparatus. This apparatus may begenerally of conventional design, except that the other chamber is shorter, as it is the lower two-thirds of the conventional upper chamber that is divided to provide a sec- 35 and low pressure chamber ii separated as indicated from that at 86, jun arranged to be operated in c'onJunction therewith.

In the lower end of the upper chamber 36 is disposed a condenser 31 adapted to return condensate to-the lower'chamber l0. Uncondensed gas material is withdrawn through the conduit 38 and supplied to the heat transfer means .45 disposed in the lower end oi the chamber 40.

means 39 and gas withdrawal connections d 41' which communicate with intermediate p0 ts in the chamber It.

Chamber has a distributing head ll and dephlegmating means 42, conduit 43 being arranged to lead condensate of relatively high nitrogen concentration from an upper shelf in the chamber 30 to the head ll. A conduit 4: leads from the lower end of the heat transfer means 45 to supply gas material, in this case,'condensate, to the head ll. A conduit 48 leads from the top of the chamber It to convey away uncondensed, low boiling point gas materials. 1

In operation, the apparatus shown in 2 operates similarly to that shown in ,Fig. '1. In vconsequence, a liquid having an increased concentration of ongen collects in: the kettle 88 along with the undesired h ilh'bolllng Point impurities. In the upper chamber 36, a liquid 05 collectsabout the condenser 31, which is substantially pure oxygen butior the high boiling point impurities whicharecontainedtherein; Theoxygen content is here vaporized and the gaseous omen and volatile materials are conveyed by gen free of high boiling point impurities. This is withdrawn when desired through the conduit 49.

Since certain changes may be made in the above construction. and different embodiments of the invention could be made wthout departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. Apparatus for producing oxygen substantially free from high boiling point material comprising in combination a high pressure rectifying column having a liquid space at its lower end and a gas space thereabove provided with dephlegmating shelves, a pair of low pressure rectifying columns arranged tobe operated in series having liquid spaces at their lower ends and gas spaces thereabove provided with dephlegmating shelves inserted therein, a plurality of connections between the gas spaces of said low pressure rectifying column, a connection leading from the liquid space of said high pressure column and arranged to discharge in the gas space above the dephlegmating shelves of one of said low pressure rectifying columns, a connection leading from a shelf in said high pressure rectifying column arranged to discharge in the upper portion of the gas space of the other of said low pressure rectifying columns, a condenser in the liquid space of said first-named low pressure rectifying column arranged to receive uncondensed vapors from said high pressure rectifying column, a condenser in the liquid space of said second-named low pressure rectifying column arranged to receive uncondensed vapors from said first-named condenser, and a connection leading from said second-named condenser to the gas space above the dephlegmating shelves of said second-named low pressure rectifying column.

2. Apparatus for producing oxygen substantially free from high boiling point material, comprising, in combination, a high pressure rectifying column, a pair of low pressure rectifying columns, one of said low pressure columns being provided with a vent, a pair of independent connections leading from respectively diflerent points in the gas space of said high pressure column to substantially the same point in the gas space of said vented low pressure column, another connection leading from the liquid space of said high pressure column directly to the gas space of the other of said low pressure columns whereby liquid fractions may be supplied thereto, a pair of condensers disposed respectively in the liquid spaces of said low pressure columns and connected in series in one of said independent connections whereby uncondensed vapors received therein from said high pressure column are successively cooled and supply the heat of fractionation to said low pressure columns, said condensers being arranged to pass the condensate resulting from said cooling to the gas space of said vented low pressure column, and a plurality of common connections dispomd to eflect free commimication between the gas spaces of said low pressure columns at relatively difierent points.

3. Apparatus for producing oxygen substantially free from highboiling point material, comprising, in combination, a high pressure rectifying column, a pair of low pressure rectifying columns, one of said low pressure columns being provided with a vent, a pair of independent connections leading from respectively diiferent points in the gas space of said high pressure column to substantially the same point in the gas space of said .vented low pressure column, another connection leading from the liquid space of said high pressure column directly to the gas space of the other of said low pressure columns whereby liquid fractions may be supplied thereto, heat exchanging means disposed in each of said low pressure columns and connected in series in one of said independent connections leading to the gas space of said vented low pressure column, and common connections arranged to effect free communication betwen the gas spaces of said low pressure columns.

4. Apparatus for producing oxygen substantially free from high boiling point material, com prising, in combination, a high pressure rectifying column, a pairof low pressure rectifying columns, one of said low pressure columns being provided with a vent, a pair of independent connections leading from respectively different points in the gas space of said high pressure column to substantially the same point in the gas space of said vented low pressure column, another connection leading from the liquid space of said high pressure column directly to the gas space of the other of said low pressure columns whereby liquid fractions may be supplied thereto, a pair of condensers disposed in the liquid space of each of said low pressure columns and connected in series in one of said independent connections that lead to the gas space of said vented low pressure column, and a common connection arranged to effect free communication between the gas spaces of said low pressure colunms.

5. Apparatus for producing oxygen substantially free from high boiling point material, comprising, in combination, a high pressure rectifying column, a pair of low pressure rectifying columns, independent connections leading from respectively di'flerent points in the gas space of said high pressure column to substantially the same point in the gas space of one of said low pressure columns, another connection leading from the liquid space of said high pressure column directly to the gas space of the other of said low pressure columns, heat exchanging means disposed in each of said low pressure columns and connected in series in one of said independent connections whereby the uncondensed vapors .passing therein upply the heat of fractionation to said low pressure columns, and a common connection arranged to effect free communication betwen the gas spaces of said low pressurecolumns.

GEORGE J. BOSHKOFF.