US1346967A - Method of and apparatus for recovering ammonium chlorid - Google Patents

Description

M. E. MUELLER.

TUS FOR RECOVERING AMMONIUM CHLORlD.

METHOD OF AND APPARA APPLICATION FILED JULY 21 Patented July 20, 1920.

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MAX E. MUELLER, F YOUNGSTOWN, OHIQ.

' Specification of Letters Patent.

Patented July 2o, 192a,

Application filed July at, is e. Serial an. elast c.

to explained and the best mode in which l have contemplated applying that principle, so as to distinguish it from other inventions.

The present improvement relates more particularly to a method of obtaining ammonium chlorid, and other fixed ammonia salts produced in the carbonization oil coal, in the form oi a concentrated solution, and then recovering such ammonium chlorid and my other ammonia salts from such solution.

improvements in apparatus for use in such recovery process are also comprehended. As recognized in such standard texts as Wagners Goal Gas Residuals (page 9%), the

5 ammonia thus combined has heretofore only been liberated by the addition of some stronger alkali, lime, in the form of milk of lime, being usually introduced into the solution for this purpose This process, how- ,ga ever, requires the use oi large quantities of lime, and furthermore the chlorin present is lost. 0n the other hand, to distil from the aqueous condensate from the gas resulting from the carbonization of coal, only the volatile ammonia contained therein, and

then to recover the ammonium chlorid and other non-volatile ammonium salts by con-- centrating the residual liquor by evaporation and crystallization, involves the evapso oration of such a large volume of water that the process is not advantageous.

The object of the present invention accordingly is the provision of a method whereby the greater portion of the nonvolatile ammoniumsalts, together with only a small proportion of the volatile ammonium salts, may be obtained in a relatively concentrated solution separate and apart from the bulky aqueous condensate, which will to hence contain only a small proportion of such non-volatile ammonium salts. From this relatively concentrated solution, ammonium chlorid and other ammonium salts may then be readily recovered by the steps 5a presently to be set forth. The invention also has as its object the recovery of the small proportions of volatile ammonium compounds remaining in the condensate.

To the accomplishment of the foregoing and related ends, the invention, then, consists or the steps and means hereinafter fully described and particularly pointed out in the claims, the annexed drawing and the following description setting forth in detail certain means and one mode of carrying out the invention, such disclosed means and mode illustrating, however, but one oi" rious ways in which the principle ofthe invention may be used.

in said annexed drawing The single figure there appearing is a dIagra-mmatic representation of an approved apparatus designed for the carrying out of my present process.

Referring first bf thus illustrated, the collector main 1 of a number or" coke ovens or retorts (not shown) is connected through one or more pipes 2 commonly known as the cross-over or foul main, with the cooler or condenser 3 in which the gas collected from such ovens or retort-s is cooled, such gas being drawn through the pipes and cooler in question by means of the exhauster or gas pump Before being discharged from the apparatus, the gas passes through a tar extractor 5 where the last of the tar is removed thererrom.

Preferably located at a somewhat lower level than condenser 3 and tar extractor 5 1s a tank 6 which is designed to receive and contam a mixture of tar and aqueous liquor. Apump 7 having its intake connected with said tank is adapted to elevate such mixture of tar and equeous liquor through a branched pipe 8 to collector main 1 and cross-over main 2. This mixture, as it collects in the bottom of said mains 1 and 2 along with any condensation from the gas that may be added thereto, is returned again to tank 6 by means of pipes 9 and 9. It will thus be seen that a circulation of the llquid contents of tank 6 is'maintained by means of pump 7 through pipes 8 and 9 and the intervening portions of mains 1 and 2.

Pipes 9 and 9 are also adapted to be connected through branches 10 and 10 of pipe 1f) with a tank 11 whereby a portion of such circulating liquid can be transferred to said tank and there allowed to stand and separate, following which the aqueous liquor is transferred to an evaporator (not shown).

all to the apparatus r The aqueous and tarry condensates from the condenser 3, exhauster 4 and tar extractor .5 are collected by means of a pipe 12 having suitable branches 12, 12 and 12, and, discharge into a separating tank 13, where, as in the case of tank 11 such aqueous and tarry portions of the condensate are allowed to separate. The tarry portion of the condensate may then be transferred through pipe 14 to tank 6, or by means of a branch pipe 14 direct with the suction line of pump 7. Similarly a portion of the aqueous condensate from said tank 13 maybe transferred by pipe 15 to said tank 6, or through a branch 15 direct to the suction line of pump 7, the main portion of such aqueous condensate being removed from tank 13 through another pipe (not shown); while by means of yet another pipe line 16 having one branch 16 connected near the bottom -of tank 11 and another branch 16 connected near the top of said tank, either aqueous or tarry liquor from said tank can be returned to tank 6.

The method of operation of the foregoing apparatus, in' carrying out my improved method or process, may now be set forth as follows, viz. :Tar, carrying with it a small proportion of aqueous condensate, is pumped from tank 6 by pump 7 through pipe 8 to mains 1 and 2. The water entrained in the tar absorbs from the gas in these mains the non-volatile. ammonia compounds, while at the same time the heat of the gas evaporates some of such water and also liberates most of the volatile ammonia present therein. The major portion of the tar, which is thus sprayed into mains 1 and 2, together with the tar thus condensed from the gas in these mains, is returned to tank 6. The tempera--' ture, however, of such returned tar will obviously be higher than when thus sprayed into said mains, and in order to prevent such temperature from rising to a point where trouble will result from foaming or boiling, a sufficient quantityiof comparatively cool tar which has condensed from the gas in cooler 3, exhauster 4 and tar extractor 5, or which 'has been separated from the aqueous and tarry mixture in tank 13, is added to the circulating system through the appropriate pipe connections. If still further cooling of the tar in such circulating system is required, a portion of the aqueous condensate from said tank 13 may be transferred through pipe 15.

The volume of tar in the circulating system is maintained approximately constant by removing a portion of the circulating liquid either continuously or intermittently through pipe 10 and transferring same to separating tank 11 where the tarry and aqueous portions are allowed to separate out as previously described. The aqueous liquid that thus separates out contains the amsired further to increase the concentration of the ammonium salts in this aqueous liquor in tank 11, a portion thereof may be withdrawn through branch 16 of pipe 16 and added to the circulating system for the p purpose of cooling the tar in tank 6 in place of similar liquor from tank 13 being used for this purpose. To avoid the loss of the small proportion of volatile ammonium compounds, the solution, before evaporation, may be neutralized with hydrochloric acid, or the ammonia of such compounds may be recovered from the vapors from the evaporator by any of the usual methods, as for instance, by passing these vapors through an acid solution.

It .will be seen from the foregoing de scription that I circulate through the mains, from which the gas flows from the carbonizing chambers to the coolers or exhausters, either a tarry or an aqueous fluid, or a mixture thereof, which to this extent resembles current practice. However, in order to obtain a relatively concentrated solution of non-volatile salts, I remove this circulating fluid from such gas mains before the gas is cooled to a temperature at which much water vapor condenses from the gas, and I further keep this circulating fluid separate from the bulk of the aqueous condensate which separates from the gas as the latter is further cooled.

In other words, the fluid, usually consisting of a mixture of aqueous and tarry liquors, which is circulated through the gas mains, is transferred only gradually (either continuously or intermittently) to the tank or reservoir where the tar and aqueous portions are allowed to separate. Such aqueous portion accordingly will contain a high proportion of non-volatile ammonium salts, and it is commercially feasible to recover these by the ordinary process of evaporation and crystallization. Instead of replacing the liquid which has been transferred from the circulating system with a portion of the condensate, either tarry or aqueous or both, which separates from the gas as the latter is further cooled, water may be substituted of the one explained, change being made as regards the steps or mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

my invention may be employed instead,

I therefore particularly point out and distinctly claim as my invention 1-- 1. In a method of recovering ammonium chlorid and other fixed ammonia salts resulting from the carbonization of coal, the steps which consist in repeatedly passing a limited body of aqueous and tarry liquors in contact With the gaseous products of such carbonization, prior to the cooling thereof .and extraction of tar therefrom, the temperature being kept above that at which much water vapor condenses fromsuch gas, and replacing such liquors gradually with similarffesh liquors from the cooling and tarextraction stages.

2. In a method of recovering ammonium chlorid and other fixed ammonia salts resulting from the carbonization of coal, the steps which consist in repeatedly passing a limited body of aqueous and tarry liquorsin contact with the gaseous products of such carbonization, prior to the. cooling thereof and extraction of tar therefrom, the temperature being kept above that at which much water vapor condenses from such gas, withdrawing such liquors gradually as they are added to by condensation from such gas, andv at the same time replacing the same gradually with similar fresh liquors from the cooling and tar-extraction stages;

3. In apparatus for recovering values from coal gases, the combination with the gas main leading to a condenser and tar-extractor, of means adapted to circulate a mixture of aqueous and .tarry liquors through said main, a storage and separating tank, and connections for diverting a portion of such liquors from said circulating means to said tank.

4. In apparatus for recovering values from coal gases, the combination with the gas main. leading to a condenser and tarextractor, of means adapted to circulate a through said main, a storage and separating tank, connections for diverting a portion of such liquors from said circulating means to said tank, and other connections for returning either aqueous or tarry liquor, as desired, from said tank to said circulating means.

5. In apparatus for recovering values from coals gases, the combination with the gas main leading to a condenser and tar-extractor, of means adapted to circulate a mixture of aqueous and tarry liquors through said main, a storage and separating tank, connections for diverting a portion of such liquors from said circulating means to said tank, other connections for returning either aqueous or tarry liquor, as desired, from said tank to said circulating means, and means adapted to supply to said circulating means either aqueous or tarry liquor, as desired, from said condenser and tar-extractor.

6. In a method of recovering ammonium chlorid and other fixed ammonia salts resulting from the carbonization of coal, the steps which consist in repeatedly passing a limited body of aqueous and tarry liquors in contact with the gaseous products of such carbonization, prior to the cooling thereof and extraction of tar therefrom, the temperature being kept above that at which much water vapor condenses from such gas, and replacing such liquors gradually with similar fresh liquors from the cooling and tar-extraction stages, such fresh liquors including substantially all of the tar from the stages in ques tion and only suflicient of the aqueous condensate to maintain a suitable temperature in the circulating liquors.

7. In a method of recovering ammonium chlorid and other fixed ammonia salts resulting from the carbonization of coal, the steps which consist in repeatedly passing a limited body of aqueous and tarry liquors in contact with the gaseous products of such carbonization, prior to the cooling thereof and extraction of tar therefrom, the temperature being kept above that at which much water vapor condenses from such gas, withdrawing such liquors gradually as they are added to by condensation from such gas, and at the same time replacing the same gradually with similar fresh liquors from the cooling and tar-extraction stages, such fresh liquors including substantially all of the tar from the stages in question and only suflicient of the aqueous condensate to maintain a suitable temperature in the circulating 1i uors. I

igned by me, this '15 day of July, 1919. I MAX E. MUELLER.

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