USRE18902E

USRE18902E - method of producing hydrogen sulphide r

Info

Publication number: USRE18902E
Authority: US
Publication date: 1933-07-25

Description

G. LYNN ET AL METHOD OF PRODUCTNG HYDROGEN SULPHIDE July 25, 1933.

. 2 Sheets-Sheet Original Filed May 7% a AT ZNEYJ G. LYNN ET AL 7 July 25, 1933. METHOD OF PRODUCING HYDROGEN SULPHIDE Re. 18,902

i 2 Sheets-Sheet 2 Original Filed May 19, 1930 TTORN EYJ Reissuecl July 25, 1933 UNITEDSTATES PATE K. nnrizennn,

PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA METHOD or rnonucms HYDROGEN SULPHIDE Original No. 1,862,900, dated June 14, 1932, Serial No. 453,592, filed May 19, '1930. Application for reissue filed February 15, 1933. Serial No. 657,756.

This invention relates to the production of hydrogen sulphide by a'simple, inexpensive method, and more particularly to its production from, sulphur by a Wet method particularly adapted for practice in connection with the production of sodium carbonate by the amlnonia'soda process, such improved method also producing as another valuable product sodium thiosulphate or some other sulphuroxygen salt of sodium.

One object of the invention is to simplify and cheapen the production ofhydrogen sulphide and supply a new source of thiosulphate; and another object is to improve the operation of the ammonia soda process by the production for. use in that process of cheap hydrogen sulphide by a method which utilizes the ingoing substances or output products of the ammonia soda process itself.

In the drawings, Fig. 1 represents, somewhatdiagramlmatically, a simple .form of ap paratus for producing hydrogen sulphideaccording to our method; and Fig. 2, is a diagram illustrating practice of the invention in connection with the ammonia soda prop-r,

ess. I

According to the present invention, hydrogen sulphide is produced. by a wet method as the result of a reaction or reactions in the presence of Water between sulphur and a suitable alkali or alkaline substance. Such a method, properly performed, not only produces hydrogen sulphide, but also produces a sulphur-oxygen salt, such as the thiosulphate or sulphate of the particular alkali employed, and may also produce (30 as an additional product, as will appear. The method is therefore suitable for practice for the production of any one or more of the hydrogen sulphide, the CO or the 'thiosulphate, or the like, whichever may be the most important. For convenience, in the present description, the invention will be discussed from the standpoint of primary production of hydrogen sulphide with the CO and thiosulphate or the like referred to as by-products, although not necessarily limited thereto.

The several ingredients or raw materials mixed together are subjected to heat and preferably to a relatively high temperature unlar to the heating arran.

der conditions favorable for complete reactlon, the result being the conversion of practically all of thesulphur, part ofwhich becomes hydrogen sulphide and part thiosul phate or the like. In practice, it is found that a relatively high temperature is preferable because of the reduction in the time for reac-.

tion. Usually, temperaturesabove the normal boiling point of the solution are most satisfactory; although lower temperatures may be employed. For convenience it is.

found desirable to conduct the reaction under pressure greater than atmospheric, thereby enabling temperatures above the normal boiling point of the solution tobe produced and-ma1ntained,-.with resulting rapid action and more nearly complete reaction between the substances under treatment. 1

While the process may be performed. either of pipes '5 joined at their ends to plates 6 enabling the material which is treated to circulate through the pipes- 5, heating steam being circulated through the chamber 1' from the supply pipe 7' to the outlet pipe 8.

'Thc upper part 11 the clr" charging door, communicates by, a pipe 10 with a suitable cendenser h may be of any suitable form, such as a iX condenser. In the arrangement shown, this condenser is constructed in a nner somewhat simi- Rent at bottom of the treating retort. That is to it comprises a casing 11 in. which are two plates 12 connected by a series of tubes 13 within a chamber 1 1, enabling the dischar'g through the pipe 10*to be passed throi the chamber 14 around the tubes 13 to an outlet p pe 15. Cooling water is" circulated through the pipes, flowing into the upper end GEORGE LYNN, or WADSWORTH, ANDEDWARD IE.- ALLEN AND B3 or BARBERTON, OHIO, AssIeNons- T0 rrrrsnunon rLA rneLnssI cola-teeny, or

belew the of the casing from a supplypipe 16, thence the outlet pipe 17, which preferably has a riser 18 for insuring that the condenser shall at all times be full of water. I,

The gas outlet pipe is preferably provided with pressure controlling and maintaining means, such as a valve 19 adjustable to open at a given pressure,a safety relief valve 20 set to blow oil at a somewhat higher pressure, a pressure gauge 21, and a hand valve controlled by-pass 22 to fully open the outlet pipe when desired. Beyond these devices the outlet pipe may communicate with suitable purifying devices" conventionally indicated at 23 and thence witha receiver 24.

In the use of this apparatus, the anatrials to be treated are charged into thecha'mber 1 through the door opening at 3. The sulphur may be any form of sulphur, such as raw or native sulphur, with purity depending upon the desired purity of the final products. The alkali or alkalinematerial may be of any suitable or desired form,-butpreferably should be a compound'of oneof'the alkali metals.

For example, the hydrate, carbonate, bicarbonate, sulphide or any suitable equivalent, may be. employed. In each case, one

' product, will be hydrogen sulphide as a gas,

either pure or mixed with C0 forv example; while still another product isa sulphur oxygen salt, such as' the thiosulphate, sulphate or. the like, of the particular alkali em ployed' Assuming then thatfthe retort is charged with su1phur, caustic soda and water, steam is. circulated through the heating chamber and the temperature rises. By proper setting of the'valves l9. and 20, a temperature above the normal boiling point of the solution at atmospheric pressure may readily be produced and maintainedQ, At a suitabletemperature the reaction isquie'kly carried to completion, essentially all otthe sulphurbeing converted either to hydrogen sulphide by combination with the hydrogen of the water or to .thiosuphate by combination with the alkali metal, and oxygen from the water." The reac'tionor reactions may be more or less progressive or by steps, and

"hence are somewhat difiicult or" exact definition. There is apparently a primary stage in which the sulphur'goes into solution as polysulphide, since observation of the reaction in a glass retort indicates molten sulphur initially floating on. the surface and later disappearing with simultaneous darkening of the solution, butsuch reaction is uncertain. In'any event, the reactions possibly may be somewhat as follows:

By reaction (A) part of the sulphur joins the hydrogen on the one hand and part the oxygen on the other to form hydrogen sulphide and S0 respectively. The S0 thereupon reacts as in (B) with the alkali or alkaline substance present for the production of sodium sulphite. But, more than that,

the sodium sulphite continues to react as in (C absorbing additional sulphur with the ultimate production of the thiosulphate, so

that the combined reactions result in the productlon from the lnltial'1ngred1ents,'including water, of hydrogen sulphide and the t sulphate, with additional evolution of CO in case the alkali or alkaline substance is a carbonate or bicarbonate.

From the theoreticalstandpoint, reaction I A ordinaril would not take lace to an removed due to'the boiling, these two effects causing the reaction to go to essential. com- .pletion. The H 8 (andCO if present) accompanied by steannpa'sses to the condenser Where the steam condenses and is permitted to trickle back to the retort, but the H 8 (and CO if present) is permitted to pass oil at the top of the condenser.

The residue, consisting principally of solu* tion' of sodium thiosulphate, may readily be purified by removing impurities in any suitable manner. Some sodium sulphide may be formed and it may be removed by FeSOr or some other soluble salt of a metal forming" an insoluble sulphide. The thiosulphate may be separated its forms. v. V

A suitable operating pressure for use with one hundred twenty-five pounds steam presby crystallizing in one of 'sure in the heating belt, is about sixty pounds per square inch, and the operating temperaturemay be about 350 F. However, the operation is not limited to these conditions, which are satisfactoryif the H S is required ingaseousform, for by-increasing the boilmg temperature and the pressure, the latter can 'bermadeto exceed the liquefaction pressure and the H S can be produced directlv in liquid form without further, mechanical compression. This isparticularly true when the condenser Water isrnade cool enough to maintain in the condenser a temperature at least as low as ordinaryroom temperature, 70 '1 Even lower temperatures are advantageous. Of course, when liquid is desired, it is preferable to avoid having (IQ;

p.resent,'by'using an alkali other than a car- I bonate, such as Na S or NaOI-l. More than;

that, by utilizing these higher boiling term- '10 carbonate or the like, may firstbe furnaced the productmay bee-rushed or ground andperatures and pressures, the method may be carried out tor the production of other'sulphur-oxygen salts of the particular alkali substance as separate ingredients, but sul-- phur and an alkali or alkaline material, such caustic soda, sodium bicarbonate, sodium or fused together with some reaction, and

charged into the hydrogen sulphide genera tor for reaction, as described. "Or, the two materials may be mixed wet, heated and dried, and introduced with or without fusing into the retort. In either case, the reactions and the products are approximately those heretofore described.

As a speoific'instance of practice of the process, 80 grams of caustic soda dissolved in 120 grams of water were treated with 128 {trams of sulphur in an apparatus fitted with a reflux condenser, as described. Boiling was carried on at apressure of sixty pounds per square inch to increase the speed of reaction and for a suiiicient length of time until little or no further hy ,rogen sulphide was evolved. There was some evidence of traces of higher sulphides of hydrogen than H S having been formed. After cooling down, the residue in the r tort was a syrupy, supersaturated solution consist-ing largely of sodium thiosulphate containing small amounts of soluble sulphide and suspended iron suiphide. This was diluted with water and sufl'icient FeSO was added to combine With the soluble sulphide. The solution was filtered hot and allowed to cool, whereupon crystals 1 of a hydrated sodium thiosulphate were produced.

In another instance, where the invention varied from eighty pounds to one hundred thirty pounds, the pressure being increased as the process continued, because during the later stages the yield or gas flow reduces and a higher temperature is desirable to speed the process and tends to increase the rate of yield. The pressure of the gases developed, to wit, hydrogen sulphide and carbon dioxide, varied from sixty to ninety pounds, and the rate of production was from five to ten cubic feet per minute.

The method described is of particular advantage in connection with the ammonia soda process, where it is the practice to supply to the circulating liquids a small proportionof hydrogen sulphide for thepur pose of correcting the tendency of. small quantities of iron to discolor the final prodnot. The eflect of the hydro-gen sulphide may either beto precipitate FeS and there by remove it in the settling operations,or to some extent coat the innersurfaces of the containers with a-film of FeS and thus assist in preventing corrosion. ,Whatever may be the efliect, a small proportion of hydrogen sulphide is always employed. In practice this material has commonly been introduced into the system by use of crude ammonia containing a relatively high hydrogen sulphide content, for which ammonia it is usually necessary to pay a premium; AC1 cording to the present invention, any 'ordi- -naryammonia with a low hydrogen sulphide content may be employed', with consequent reduced ammonia cost, and the hydrogen sulphide may be produced by our method and be introduced separately to the apparatus. As a consequence, the hydrogensulphide content of the liquor is wholly inin hydro en sulphide. b

According to our scheme ofoperat-ion, as

represented diagrammatically in Fig. 2, a portion of the'alkali carbonate produced by the plant, either the bicarbonate or the normal carbonate, is diverted and is introduced into the hydrogen sulphide generator or retort R for treatment under proper conditions with water and sulphur for the production ofhydrogen sulphide and CO This retortis operated in the manner before described, its product being H S and CO and sodium thiosulphate. The gases are led back. into the system at any suitable place, such as to the absorber A, although the particular place is immaterial. There is no economic loss 'of CO By operating the hydrogen sulphide retort Rwith a production value in step with the requirements for hydrogen sulphide, the Fe correcting value always may be manipulated to keep pace withfvariations in conditions and always independently of or to take account of variations in the ammonia composition.

The thiosulphate produced as a by-prodnot has a value of approximately $40.00 a ton in the open market today, and of course may be refined and its value'thereby recovered. Obviously, therefore, the invention not only improves the practice of the amk monia soda process by divorcing the hydrogen sulphide content from the ammonia inp '95 tage of hydrogen sulphide and falling too i low when the ammonia'is lean put,but also enables sodiumthiosulphate to be produced as a valuable by-product.

Whatweclaimisz, 4, 1. The method of producing hydrogen sulphide from sulphur and an alkali substance consisting in heating togethersulphur and alkali substance in the presence-of ater at a temperature and pressurehigh enough so that the hydrogen sulphide thereby pro duced liquefies Without further compression.

2. A method consisting inheatin'g togeth er sulphur andan alkali substance in the mal boiling point of Waterand at a pressure presence of Water at a. temperature above the normal boiling point ofwater and ate. pressure aboveatmospheric, thereby producing hydrogen sulphide and a sulphur containing compound of the alkali employed, and con- 7 tinuing the reaction at such temperature and pressure until the sulphur containing com: pound'becomes a sulphur-oxygen salt V 3. A method consisting in heating together sulp'hurand an alkaline substancein the presence ofwater at a temperature above the norabove atmospheric, thereby producing a vapor containing, ,amongother things, hy-

drogen sulfide gas, fractionally'condensmg i sulphate;

the vapor and returning the aqueous condensate, to thereby separate the hydrogen sulfide,

and continuing the reaction at'the said temperature and pressure until the alkali metal is converted to thiosulphate.

4. A modified ammonia soda process, consisting in diverting a part of the alkali carbonate, subjecting the same to heat in the presence of Water and sulphur, thereby forming carbon dioxide and hydrogen sulphide, and introducing the carbon dioxide and hydrogen sulphidev thereby formed to the ammonia soda cycle. V

. v5. modified ammonia soda process, consisting in diverting a part of the alkali carbonate, subjecting the same to heat in the presenceof Water and sulphur, thereby forming as gas a mixture of carbon dioxide and hydrogen sulphide and also forming a sulphur-oxygen salt of the alkali, introducing the mixture of carbon dioxide and hydrogen sulphide gases to the ammoniasoda cycle, and recovering the sulphur-oxygen salt as thio- .GEORGE LYNN.

EDWARD lM ALLEN. BRAZIERK. BEECHER.