US2398817A

US2398817A - Method of separating gases or the like

Info

Publication number: US2398817A
Application number: US365415A
Authority: US
Inventors: Nelson C Turner
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-11-13
Filing date: 1940-11-13
Publication date: 1946-04-23
Anticipated expiration: 1963-04-23

Description

I April 1946. N. c. TURNER 2,398,817

METHOD OF SEPARATING GASES OR THE LIKE v I Filed NOV. 13, 1940 2 Sheets-Sheet l April 23,1946. N. c. TURNER METHOD OF SEPARATING GASES OR THE LIKE Filed Nov. 13, 1940 2 Sheets-Sheet 2 INVENTOR.

W C 7M BY W M I AM PM... Apr. 23, 1946 UNITED STATE METHOD OF SEPARATING GASES OR THE LIKE Nelson C. Turner, Tulsa, Okla.

Application November 13, 1940, Serial No. 365,415

' 7 Claims.

This invention relates to a method of separating case's. vapors or liquids, particularly light hydrocarbon gases or vapors such as ordinarily occur in natural gas, the method hereinafter described bein: particularly intended for laboratory analysis, although it may also be utilized for industrial gas fractionation.

The method of separating light hydrocarbon gases most generally employed consists in the condensation of the hydrocarbons at low temperatures by cooling, with liquid air, and then fracpoint between two successive hydrocarbons is often ill-defined and leaves much to human jud ment in the determination of the volume of the component which has been distilled.

In accordance with the present invention, the use of liquid air or other low temperature cooling medium is dispensed with. The method invention employee a substance capable of adsorbing the gases which are to be separated and means for driving the pure gas fractions from said adsorbing material in the sequence in which they are released by fractional distillation.

The present invention provides sharper separation between the individual components of the gas than was possible heretofore. It also provides a much more rapid analysis which in some instances may be completed in about one-fifth oi the time required by the low temperature fractionating method.

The invention will become more apparent from a consideration of the accompanying drawings in which like reference characters designate like parts and in which:

Fig. 1 is a diagrammatic view of apparatus for separating gases embodying the principles of this invention;

Fig, 2 a side elevational view partially in section oi a fractionation column;

Fig. 3 a view diagrammatically illustrating a portion of the fractionating column and adjust-' able heating means therefor;

Fig. 4 a diagrammatic illustration of an adjustable manometer coupled to a plurality of electronic relay control circuits; and

Fig. 5 a diagrammatic view of a fractionating umn to unusual problems.

column and mechanically adjustable heater and mercury container.

With reference to Figs. 1 to 3 inclusive of the drawings, the numeral I designates a gas fractionating column having progressively reducing cross-sectional areas forming chambers of such proportion that the internal cross-sectional area at the outlet end 2 is only a small percentage of the internal cross-sectional area of chamber 3 at the inlet or entrance end of the column. The column may be provided with this 4 for rapid heating and cooling.

The fractionating column I is filled with an adsorbing material such as activated cocoa-nut shell charcoal I, Fig. 3, and a heating means such as an electrical heater 5 is provided to drive the gases out of the adsorbent material. Heater 5 is movable vertically of the column, as shown in Fig. 5, it being shown in the extreme bottom position in Figs. 1 and 5, and moved slightly upward in the position of Fig. 3, the heat being applied locally beginning at the large end of the column;

Mercury from a movable reservoir 6 is introduced part-way into the heated zone ofthe column to bring it to the boiling point, and its vapors are employed to' clean the adsorbent charcoal of the adsorbed gases. As the adsorbent in the lower zones is freed of gases, the heater 5 and mercury reservoir 6 are raised to a fresh portion of the packing to successively drive off the gases in succeeding zones. The heater is movable with the mercury container by means of a yoke 6 and a motor drive.

In Fig. 5,the mercury container 6 is of annular form and movable on a column 6. It is supported by a cable 6 passing around pulley 6 down through the column and around pulleyt a drive drum 6 and a spring biased take-up drum 6 Drum 6' is driven by a motor 6 which is controlled by an electronic relay 59, Fig. 4.

The mercury container 6 is connected by a fiex ible conduit 6 to the bottom of the fractionatina column I. Valved connections 6 and 6* of Fig. 3 are provided, one for admission of samples and the other for the purpose of flushing-out the sampling lines.

As shown in the drawings, the fractionatina column is generally. mounted vertically with its larger end at the bottom. It may, however, be placed in a reclining position or oriented in any other way for special uses in adapting the col- A by-pass tube I, Fig. 1, may be connected into the column at some point along its length to indicate during sampling the progress of the heavier constituents oi the mixture being adsorbed. The by-pass tube is provided with a valve 8 so that the gases may be forced to leave the column through the small outlet end 2, controlled by valve 9, from which the gases pass to enter the condenser l3 from separator I and by a capillary tube. I4 pass to a junction I5 which is connected to the low pressure side of an adjustable manometer l5, Figs. 1 and 4, and from which the gas flows to a volumeter II through a thermal conductivity cell l8 and a temperature equalizing coil 20.

The high pressure side of manometer I5 is connected to separating chamber ill by tubing I 9, but there isno gas flow through I9 because of the liquid seal in the manometer. The gases pass through the thermal conductivity celll8, then through a temperature equalizing coil 20, which is connected to the top of the volumeter ll. The thermal conductivity cell I8, coil 20 and the volumeter ll may be immersed in a constant temperature bath contained in a tank 2|; agas outlet 22 extends from the volumeter, as shown in Fig. 1; or gases may be withdrawn from outlet :2, Fig. 1. v

Fig. 4 shows arrangements of

contacts

61 and 68 of the electronic relay 59 with the manometer.

The manometer I6 for the automatic control of the gas flow during the distillation consists of a U-tube having a bulb I6 and a tube I5", the

- mixture have penetrated the latter having graduations I5. Numerals I6 and I Ii designate the water levels in the manometer which are an indication of the rate of flow of the gases in line ll, Fig. l The bellows adjustment provides for slight variations in rate at which gas flow is maintained, major variations of rate being controlled by changing size of capillary I4, Fig. 1.

The motor 5 which raises, the heater 5 and mercury chamber 6, and the energization of heater 5 is controlled through relays 59 by rate of gas flow through capillary I4 by means of the manometer I 5. in bulb I5 are connected to

contacts

61 and 68 of a pair of relays 59. Electrode II is longer than I2 and controls the motor circuit which moves the heater 5 vertically on the fractionating column I.

The water in the U-tube is electrically connected in the relay circuit by conductor 13.

traversing the ,fractionating column I exceeds a predetermined amount, the level of the water l6 makes contact with terminal Ii and energizes relay 59 to cut out the motor 6 thereby stopping further movement of the heater 5 on the column. If the gas flow nevertheless continues to increase, the level I5 of the water column will contact terminal 12 which, through the electronic relay 59, deenergizes the heater 5. When normal gas flow has been re-established the level Iii drops below the ends of terminals H and I2, and the drive and heating units are again energized to continue normal operation of the fractionating column. a

The operation of the above-described gas trac- Terminals II and I2 disposed When the flowof gases generated by heater 5 pressure.

are adsorbed by the charcoal I and when the column I is filled, as indicated by a change in thermal conductivity of eiiiuent gas, the valve of the connection 6* is shut-0H.

The by-pass valve 8 may be opened during sampling to indicate the progress of the heavier constituents oi the mixture being adsorbed. The sample is drawn oil through the by-pass I until a slight change in the composition of the effluent gas indicates that the heavier components of the packing to the point at which the by-pass begins. then discontinued and distillation of the sample is commenced, with the by-pass valve 8 closed and valve 9 open.

Mercury reservoir 6 is then raised enough to introduce mercury into-the entrance end 3 of the column, and. heater 5 is energized and the gas fractions are driven from the adsorbing charcoal material of the heated portion of the column into the upper sections of the column.

As the body of the adsorbed components is driven up through the adsorbent the tendency of the heavier components to remain behind is sufll ciently pronounced to causethe individual components to separate into layers, each layer consisting of substantially pure component. As the various components are driven through the adsorbent bed by the action of the heater, the stratum between any two adjacent components, which contains substantial quantities of both components, finally reaches a limited minimum thickness dependent upon the relative adsorption characteristics of the two components. In order that the volume of mixed gases in this stratum may be reduced to a negligible value in comparison to the volume'of pure components above and below it, the cross-section of the adsorbent bed at the outlet end of the column is substantially less than the cross-section at the charging end. Since the thickness of the stratum of mixed components is independent of the diameter of the cross-sectional area of the adsorbent bed, the volume or adsorbed components in this stratum will decrease in direct proportion to the crossare delivered from the top of the column.

The separated gases pass out of the column through the condenser I3 and separator, and flow through the capillary tube I 4, past connection block I5 of the manometer I6, and to the thermal conductivity sell I 8 from which they pass to the volumeter II.

The volumeter may be adapted for use in measuring very small amounts of gas or for metering corrosive gases or for. other specialized applications. It may be provided with a saturating chamber where the gas is bubbled through a quantity of the sealing liquid to minimize errors introduced by.varying humidity of the samples under observation. It may also be provided with a safety chamber to prevent drawing the liquid back into the inlet line in case of reversal of As previously explained, the manometer I 5 controls the rate 01' gas flow by controlling movement of the heater and the heat supplied to the fractionating column through the relays 58 in the The sampling is manner shown in Fig. 4. The normal rate of flow, as established by the capillary [4 operating manometer I 6, may be varied by adjustment of.

the bellows I 6 by screw I6 if desired.

The volumeter measures the total volume of gas passing out of the column during the time between consecutive changes in composition. From a record of the volumes of the various fractions as measured and the temperature and barometric pressures, the volume percentage of the various components may be calculated. The outlet connection 2'4." provides for the collection of isolated fractions in their purified state.

After completion of distillation of a sample, the column is preparedfor the next run by lowering the mercury reservoir and heater to. their initial positions at the bottom of the column. While the mercury is being lowered, some gas such as air or hydrogen is allowed to enter the column through the connection I l. The use of hydrogen rather than air is helpful in the analysis of natural gases and other similar samples since it is readily displaced and permits the sampling to proceed at a greater rate. In cases where these gases might interfere with the analysis of the sample, the column may be sealedduring the lowering of the mercury reservoir and the sample admitted to the evacuated column. An especially constructed column in which the mercury reservoir could be lowered approximately one meter below the sample inlet connection would be necessary for useof this vacuum technique.

By means of. the reduction in' area or the column the bulk of the adsorption of gases is made to occur near the entrance end and a long chamber is provided substantially free of the heavier components of gas mixture for refractionation and further purification of the fractions aS they approach the outlet end. The mercury entering the bottom of the column not only drives the adsorbed gases out of the adsorbent but also seals theadsorbent material during distillation so that readsorption of gases from another portion of the column cannot take place during the distillation.

Means other than the electric heater may be employed for driving the gases out of the adsorbent. However, the electric heater and the movable mercury reservoir are found to be very practical because when the heat is applied locally, beginning at the large end of the column, the mercury from the movable reservoir is introduced part-way into the heated zone where it is brought to the boiling point and the vapors clean the adsorbent of the adsorbed gases. As the adsorbent in this zone is freed of gas, the heater and mercury level are raised to a fresh portion of the packing.

The unique construction of the column consisting of consecutive chambers of reducing areas either continuously or in steps, as shown in the drawings, results in the bulk of adsorption of gases occurring near the entrance or enlarged end of the long chamber which is maintained substantially free of the heavier components of the gas mixture for refractionation and further purification of the fractions as they approach the outlet end.

It will be evident to those skilled in the art that the method of adsorption and expulsion of gases by a fractionating column, as herein disclosed. may be practlced with various forms of auxiliary equipment for measuring the volume or physical properties of the gases.

I claim: 1. The method of separating gases or vapors which comprises charging the gases or vapors into one end of an elongated container, applying heat progressively from one end to the other of the container to expel the gases from the adsorbent material, and replacing the expelled gases with another vapor to prevent readsorption of the expelled gases.-

2. The method of separating gases or vapors which comprises charging the gases or vapors into one end of an elongated container, applying heat progressively from one end to the other of the container to expel the gases from the adsorbent material, and filling the free volume between the granules of the adsorption material with mercury after the heat has been applied.

3. The method of separating gases which comprises passing the gases or vapors through a unitary mass of adsorbent material contained in an enclosed space of gradually reducing cross-sectional area and heating said adsorbent material progressively from the large to the reduced area of the mass to separate the adsorbed components into fractions of the gases in the sequence in which they are released by the distillation.

4. The method of separating gases which comprises passing. the gases or vapors through a unitary mass of adsorbent material contained in an enclosed space of gradually reducing crosssectional area, heating said adsorbent material progressively from the large to the reduced area of the mass to separate the adsorbed components into fractions of the gases in the sequence in which they are released by the distillation, and

progressively sealing the heated end of the mass to prevent readsorption of the released gases.

5. The method of separating gases which comprises passing the gases or vapors through a unitary mass of adsorbent material contained in an enclosed space of gradually reducing cross-sectional area to separate the components into stratum or fractions of the gases, and applying heat progressively to the different stratum of the gases to release them in the sequence of their occurrence. I

6. The method of separating gases which comprises'passing the gases or vapors through a mass of adsorbent material contained in an enclosed space of gradually reducing cross-sectional area to separate the components into stratum or fractions of the gases, applying heat progressively to the different stratum of the gases to release them in the sequence of their occurrence, and regulating the rate of heat application to the different stratum torelease the fractions of the gases at a substantially constant rate of flow.

7. The method of separating gases which comprises filling a mass of adsorbent material contained in an enclosed space ,with hydrogen or