US1484260A - Apparatus for sublimation - Google Patents

Description

Feb; 19', 1924.

H. D. GIBBS APPARATUS FOR SUBLIMATION 1919 2 Sheets-Sheet 1 F iled Jan. 24

- Feb. 19 1924. 1,484,260

H. D. GIBBS APPARATUS FOR SUBLIMATION Filed Jan. 24, 1919 ,E, cs-Sheet 2- Patented Feb. 19, 1924.

UNITED STATES lactate PATEN 1 omcr.

HARRY n. GIBBS, (IF-SAN FRANCISCO, CALIFORNIA, BY iuEsNE AssIemEnrs DEDI- oA'rEn 'ro THE PEOPLE o rHEUNITEn STATES FOR THEIR. FREE; USE AND Em.

JOYMENT.

. urmrus FOB sonnma'rrou.

Application filed .l'anuary 24, 1919. Serial No. 272,902..

ILEn ummn rnn A6! or MARCH 3, 1883, zasu'r. I.., 62 5.

To all whom it may concern:

Be it known that I, HARRY D; GIBBS, a citizen of the United States of America, and an employee of the Department of Agriculture, residing in the city of San Francisco, county of San Francisco, State of California gwhose post-office address is Department of griculture, Washington, D. C.), have invented a new and useful Improvement in 10 Apparatusfor Sublimation.

This application is'made under the act of March 3,1883, chapter 143 (22 Stat., 625), and the invention herein described and claimed may be used by the Government of the United States or any of its oflicers or employees in the prosecut1on of work for 'the Government or by any person in the United States, without payment tome of' any royalty thereon. v The object of my invention is substances that separate frdm'a gas or mixture of gases upon coolin and separate substances tliat are suspended in the gasor are incorporated with the gas 2 at elevated temperatures as part'of the gas phase. e

' The usual method of so purifying such substances is to heat them to a high degree, producing vaporization, and conduct the va- 80 pors, either with or without a current ofair,

into a cooling chamber where the solid particles separate out. 0r the gas is heated first and conducted over the substances to be vaporized'and thus the gas becomes charged 1 85 with the volatile substances. By this process all of the substances that separate from the gas condense in the chamber in a condition in which they are mixed together, either in the form of crystals or powder that 40 settles to the floor of the chamber or collects upon the walls. In some cases a succession of chambers have been employed, these chambers connected witheach other by large openings or doors situated at various places in the partition through which all of the vapors that escape from the 'fir'st chamber pass into the second, and so on. 7

Reference is made to the drawing, where- Figures 1, 2, 3, and 4 represent the rectangular form of apparatus, and Figures 5 and to purify the gas or gases 6 represent the cylindrical form of apparatus. Figure 1 is a cross section on line A-A of Figure 3; Fi re 2 is a cross section on line B-B of igure 4; Figures 315 and 4 represent longitudinal sections of the apparatus; Figure 5' represents a cross section of the apparatus; and Figure'fi represents a longitudinal section. Fig. 7 represents a vertical cross section of a modified type of the apparatus. 7

Further describing my invention with reference to the drawin wherein like nu-' merals denote correspon ing parts throughout: 1 denotes the screens, which may be made of metal cloth, fibers, perforated plates or other construction that provides a multiplicity of orifices, through which the ses. are passed; 2 denotes the outside she I or casing; '3 represents a rod attached to the screens 1 in such a we that the screens can be oscillated or jarre for the purpose'of removing adhering substances; 3,, represents a rod attached to-scrapers 4, arranged in such 'a way that by moving-the rod 3,, the scrapers 4 are dragged back and forth on guide rods 5, across the screens 1 dislodging material from the screens. The material dislod ed from the screens 1 or walls falls to t e bottom and collects in hoppers 6 where it is'removed by drawing slides 7. The gases, charged wit the substances to be separated, enter through the pipe 8, pass through the series of screens 1, and exit through pipe 9. f

3 represents the shaft thatrevolves and carries the scrapers 4that move against the, screens 1 so as to dislodge material from the screens 1' and thus keep the orifices open. The scrapers 4 are fitted with bristles 5, of wire or other material forming a brushing surface. The scrapers 4 in their revolution loosen the material collected upon the screens 1 or circumference of the apparatus. This material falls to the bottom of the cylinder and collects in hoppers 6 whereit can be removed by moving slides 7. The vapors carrying the materials to be separated enter through the (pipe 8, pass through a series of screens 1, an exit throu h pipe 9. To further illustrate t eoperation of my process as carried out with eitherone of through melted pht pheric 'air through gases, nitrogen, carbon ases, is passed over or alic anhydri'de, whereby the gas becomes charged with the dloxide or similar phthalic anhydride in the vapor phase, the

sition of some of the amount of phthalic anhydride carried by the gas being dependent upon the temperature of the gas, which should be above 150 centigrade. This gas, charged with the vapors of phthalic anhydride, is passed into the apparatus through the opening 8 and successively into the compartments separated from each other by the series of screens. The first compartment, C in F igure 3, is maintained by the heated gas stream at a temperature of approximately 100 centigrade. In this compartment a certain amount of heat is lost from the gas and the least volatile substances crystallizing out upon the screens and upon the walls of the apparatus. The gas stream flows through the screens 1 into compartment C where a further quantity of heat is lost from the gas and solid substances crystallize out upon the screens 1 and 1,, and the walls of this compartment. A further quantlty of heat is lost from the gas in this compartment and it passes through-the screens 1 into the compartment 0,, where it is further cooled and other solid substances crys tallize. The exit gases are carried off through the outlet 9, shown in Figure 4. When the material crystallizing upon the screens tends to clog the orifices, the handle 3 can be moved to oscillate or jar the screens and remove the adhering material. In Figure 4 the rakes 4 moving across the screens 1 are moved by handle 3. The material as it flows from the screens in the various compartments collects in hopper 6, Where it is removed by drawing slides 7.

The same procedure is em loyed with the cylindrical apparatus descri ed in Figures 5 and 6. The gasescharged with phthalic anhydride enter at the orifice 8 and pass through the screens 1 1 1 1,, into the first compartment C where a certain amount of cooling takes place with the depophthalic anhydride. The gases then .pass through screens 1 into the compartment C where afurther cooling and precipitation takes place, and so on successively into the compartments C C C through screens 1,, 1 1

The phthalic anhydride ordinarily manufactured by the air oxidation process is contaminated by naphthalene and the separation of these two constituents is very easily efi'ected by this apparatus, the phthalic anhydride separating out into pure form in the first compartment, while the naphthaprocedure 1n the case practice of my invention.

adjacent to the orifices.

Lee-ease lene separates out in the ments.

In describing in an example descri ing the steps of the complete process, it being understood that while all of the steps are not novel, they have not been heretofore employed in connection with the novel steps, for which reason they have not accomplished the results obtained in the latter compartprocess I shall first give en a current of gas is passed over or through mixtures with various volatile compounds the as will take up the volatile substances, and the proportion of volatile substances taken up will depend upon the nature of the substances, the gas, and the temperature, both of the substances themselves and of the gas. On cooling the gas some of the constituents separate out, the substances having the highest melting, sublimation and boiling points usually separating out first. I have found out that when the current of gas is charged with these volatile substances and it is caused to move through small orifices, the least volatile constituents separate or congregate or crystallize on the edges or Crystallization and separation from the vapor phase is thus assisted by the orifices and the passage of the gas through the orifices. I do not wish to confine myself to the use of any particular gas, for I have found atmospheric air, furnace gases, flue gases, carbon dioxide, water vapor, and various other vantageously employed.

The orifices may numbers in approximately the same plane in a sheet, plate or screen composed of metal, fiber or other substances, orthe aggregation of orifices may be attained by M19 use of gauze, screen or cloth woven of 'wire or spun fibers, or any material producing a partition permeable to gases.

gases may be adbe arranged in large.

I have also found that a multiple arrangearranged in circles or in segments of circles,

in spheres or parts of spheres, concentrically, or otherwise, or in any. figure of revolution, or warped or bent surfaces or form of a partition constructed of material permeable togases. arrangement of orifices possesse advantage any- I have found that onev or a permeable partition into a-third com- .tus.

The air current may be charged with the volatile constituents in various ways, for

iasaaco' example, by heating the material in a vessel and passing the air over or through the heated material; by feeding the solid or molten material into the air stream or passing the air stream over or through baflles containing the materialto be volatilized.

The air stream thus. charged is passed into the first compartment where it loses a- .portion of its heat and precipitates a portion of the materials carried. From the first compartment itpasses through the orifices,

screensor permeable partition into the second compartment, where the process of coolmg and precipitation of particles continues. and from this compartment it may be passed through another series of orifices or screens partment and so on into, and through, any number of compartments desired.

The material collecting on the screen or on the orifices may be removed by shaking 1 or jarring the screens or by scraping or brushing by hand intermittently or cont1nuously by well The material fallingfrom the-screens and condensing in the various compartments may be removed from time to time by means of chutes in the bottom of the compartment or it may be scraped from the floors of the compartment through openings placed in the side or bottom walls.

To further illustrate my process I will give the preferred procedure in the case of phtha-lic anhydride. In the manufacture of this compound by the catalytic air oxidation process the phthalic anhydride may be contaminated by greater or lesser quantities of naphthalene, naphthaquinones and other substances. The s stream containing these substances is made to enter the first chamber at a temperature of approximately 120C. The temperature of this chamber is maintained at a range between 80 C. and 120 C. The permeable partition separating this chamber from the second is made of wire cloth of mesh that may be one-quarter of an inch to one inch in size. I do not wish to confine myself to wire mesh of this size for in some instances larger or smaller mesh may be desirable. The rate of the gas stream passing through this permeable partition may be approximately three'cubic feet of gas per minute for each square foot of surface in the screen separating the filst and second compartments. In some cases the gas stream may be greatly increased with corresponding increase in theamount of the substances purified in a given time. Large of known mechanical device.

phthalic anhydride crystals separate .and form on the screen. These may fall to the floor of the compartment or may be shaken or scraped from the screen and from time to time removed from the compartment.

Impurities of various nature, including naphthalene and naphthaquinone and some pthalic anhydride, pass with the air stream into the second compartment, which is preferably larger than the first and separated from the thirdcompartment by a similar screen or permeable partition. In the sec- 0nd compartment an impure phthalic anhy- 4 dride condenses and in the third compartment the larger proportion of the naphthalene and some phthalic anhydride condense.

If the air current is very rapid andthe tem- 1 perature of the third compartment remains too high to insure a good condensation, a fourth or a fifth compartment may be provided, each increasing in size over the preceding, thus aflording more rapid cooling and slowing the rate of passage of the gas through the screens. As an example of some of the useful applications of this process, I will cite 1. The separation of phthalic anhydride.

from naphthaquinone, toluic acid, naphthalene and other impurities.

2. The separation of anthracene'pressed cake into its various constituents whereby carbazole, anthracene, and phenanthrene are obtained in a higher state of purity.

3. Benzoic acid from chlorbenzoic acid I mitting theescape of the residues, screens in'the casing between the. introducing and escape-permitting means, brushes acting against the screens, means for effecting a complete relative rotation between the.

screens andbrushe's, and means operating over the bottom between the screens for separately collecting the materials condensed and deposited in'the difi'erent compartments formed by the screens and separately discharging the same from the casmg.

2. In condensing-linechanismof the character set forth the combination with a cas-' ing, ofmeans for introducing vapors to be condensed into the casing, means for permitting the escape of the residues, screens in the casing between the introducing and escape permittinggmeans, brushes acting against the screens, means for effecting a relative movement between the screens and brushes, and means operating over the botmitting the escape of the residues, screens in the casing between the introducing and escape permitting means, and means for removing the condensed materials from the screens and means for separately collecting the materials condensed and deposited in the different compartments formed by the screens, and separately discharging the same from the casing.

4; In condensing mechanism of the character set forth the combination with a casing, of means for introducing vapors to be condensed into the casing, means for per-- mitting the escape of the residues,screens 1n the casing between the introducing and escape permitting means, means for removing the condensate from the screens, and means operating over the bottom between the screens for separately collecting the materials condensed and deposited in the different compartments formed by the screens, and separately discharging the same from the casing.

5. In apparatus of the character set forth,

thecombination with a casing, of means for introducing thereinto 1n the vapor phase and at a temperature sufficiently highlto maintain the least volatile materials in said vapor phase, a mixture of materials that respectively condense under different temperature conditions, outlet means for per-' tures at different points, a plurality of screens in the casing located at 'diiferent points across the path ofthe vapors between the introducing and outlet pointsand substantially defining said different zones, means for dislodging the materials from the screens and causing the same to be individually deposited at different points, and

means for permitting the separate individ ua'l withdrawal of the condensed materials from the casing. j

6. In apparatus of the character set forth, the combination with a casing having portions of consecutively increasing capacity, of means for introducing materials of different characteristics in the vapor stage into a portion of relatively small capacity, means for effecting the separate condensation of such materials,respectively, in the said different portions of the casing, and means permitting the discharge of the residue from a portion of relatively great capacity.

In testimony whereof, I affix my signature in the presence of two subscribing witnesses.

HARRY. D. GIBBS. Witnesses:

L. A. SKINNER, COURTNEY Conovnn.

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