US542932A - Gael kellner - Google Patents

Description

(No Model.) 2 Sheets-Sheet 1.

0. KELLNER. PROGESS 0F PRODUCING GELLULOSE No. 542,932. Patented July 16, 1895.

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(No Model.) 2 Sheets-Sheet 2. 0. KELLNER.

PROCESS OF PRODUCING GELLULOSE.

Patented July 16, 1895.

NITED STATES PATENT rrrent PROCESS OF PRODUCING CELLULOSE.

SPECIFICATION forming part of Letters Patent No. 542,932, dated July 16, 1895.

Application filed December 5, 1891. Serial No. 414,206. (No specimens.) Patented in England July 31, 1891, No. 12,970, and in Austria-Hungary December 8,1891,No.33,685 and No. 56,889-

To all whom it may concern.-

Be it known that I, CARL KELLNER, a subject of the Emperor of Austria-Hungary, residing at Vienna, in the Province of Lower Austria, in the Empire of Austria-Hungary, have invented certain new and useful Improvements in the Process of Producing Cellulose by Means of Sulfurous Acid, (for which I have obtained Letters Patent in Austria-Hungary, dated December 8, 1891, No. 33,685 and No. 56,889, and in England, dated July 31, 1891, No. 12,970,) and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters of reference marked thereon, which form a part of this specification.

This invention relates to the manufacture of cellulose by the sulfite process, and more especially to the treatment of the sulfite solution prior to its introduction into the boiler or digester.

In the conversion of fibrous materials into cellulose by the sulfite process the sulfite solution has prior to this my invention been introduced into the boiler or digester, together with the fibrous material,in acold condition,

and then heated either directly by the injection of steam or indirectly by means of a heater-coil in the digester or a heating-j acket encompassing the digester. This mode of heating the digester contents from a normal to an operative temperature takes, as is well known,a comparatively long time, which may be considered as lost time, since no practical function or operation takes place untilthe sulfite-liquor has been heated to the required temperature. On the other hand, during this operation monosultite of calcium in considerable quantities is formed, due, no doubt, to the separation under action of heat of a portion of the lime-solvent-i. a, the sulfurous aoid-whereby a portion of the lime is set free.

' prevented during the heating of the sulfite solution from a normal to the required tem- 5o perature at which there is a sufficient pressure in the digester to prevent the separation of the sulfurous acid in the form of a gas. The formation of calcium monosulfite is not only detrimental in that it forms a non-conductive crust upon the digester-walls if the digester is heated externally or upon the surfaces of the heater-coils when the digester is heated internally, requiring a greater amount of caloric to heat the contents, while the monosulfite has a detrimental action upon the cellulose in that the latter becomes more or less discolored, thereby increasing the labor and expense of bleaching.

' My invention has for its object to obviate these disadvantages by removal of all or nearly all of the monosulfite that is usually formed in heating a charge of sulfite solution from a normal to the required effective temperature before admitting the liquor to the digester, which I efiect by heating the sulfite solution in a separate vessel to the desired temperature, allowing the calcium monosulfite to subside, and then transferring the hot solution to the digester containing the material to be converted into cellulose.

It is obvious that by means of this mode of procedure the solution in the digester can be readily maintained at or raised to the desired temperature and 'a sufficient pressure estab lished within thedigester to prevent the further separation of sulfurous acid from the sulfite solution'and consequently a further formation of calcium monosulfite.

same as a solvent for the separated calcium monosulfite.

In the accompanying drawings I have illustrated heaters of simple construction, by means of which the sulfite solution may be heated before its introduction into the digester and the sulfurousacid gases evolved during the heating recovered and utilized as a solvent for the calcium monosulfite formed during such heating.

Figure l is a central vertical section of an upright heater with condenser. Fig. 2 is a longitudinal central sectional elevation; and Fig. 3, a transverse section of a horizontal heater, the condenser being omitted.

Referring to Fig. 1, the uprightheater consists of a boiler a, containing a steam-coil b, to which steam is admitted through the valved pipe 0, the water of condensation being collected in a suitable trap e, connected with theopposite terminal of the coil 1) through a valved pipe (1. At its upper end the heater has a manhole normally closed by a cover m, provided with a pressuregage, the heater having, also, a thermometer t at its upper and lower ends, respectively. In the bottom of the heater is provided a valved purge-pipe n, so that the apparatus may be cleansed from time to time, the sulfite solution being introduced through valved pi pe f and discharged through valved pipe g. At its upper end the heater is connected by a valved pipe h with one terminal of a condenser-coil j, the other terminal of the coil beingconnectcd bya pipe 7" with a suitable receiver for the products of condensation.

The condenser 7c is composed of two concentric vessels, between which the condensercoil is arranged, the inner vessel having ports in its walls at its lower end, through which inner vessel the discharge-terminal of the coil is carried. The cooling agent is fed to the inner vessel through pipe Z, thence passes through the ports into the space between the said inner vessel and "the outer vessel and up through the overflow Z.

'lhesulfurous-acid gases a nd vapors evolved during the heating of the sulfite solution are condensed in the condenser 70, and thence flow to a suitable collector, which also collects all non-condensed gases, which latter, as well as the products of condensation, are pumped back or otherwise returned to the heater, when the same is again charged in order to dissolve any calcium monosulfite formed during the heating of the previous charge of sulfite solution.

In order to facilitate the separation of the calcium monosulfite and also to hold the same in suspension as much as possible during the preheating of the solution, and thereby prevent its too rapid deposition, I prefer to provide the heater with an agitator that will keep the monosulfite in motion and prevent its deposition as far as possible, as shown in Figs. 2 and 3. In these figures I have shown a horizontal heater a inclosed within a pro tion between the coil and the trap e. The sultite solution is introduced through a perforated pipep, connected with avalved inletpipe f, and s is what is termed an oil-bag forthe reception of athermometenn being the purge-pipe and g the valved exhaust-pipe.

The operation may be briefly described as follows: The heater is charged with sulfite solution, which is heated, preferably, to a degree higher than its boiling-point, the agitator being kept in motion to prevent the deposition of the monosulfite formed by the decomposition or partial decomposition of the sulfite solution under the action of heat. When the solution has been heated to the desired temperature, the rotation of the. agitator is stopped and the calcium monosulfite separated from the solution is allowed to subside, after which the hot solution is transferred to the digester or digesters previously charged with wood. The gases evolved during the heating ofthe sulfite solution, which consist, chiefly, of sulfurous acid, (80 are conducted to the condenser 70, and from the latter to a suitable storage-vessel, to which are also conducted the gases evolved in the digesters and drawn olf after the reduction of the fibrous material. After the discharge of the hot solution from the heater and before it is again charged with sulfite solution the sulfurous acid from the storage-vessel is introduced into said heater for the purpose of dissolving the calcium monosulfite separated from the previously-heated sulfite solution, after which the heater is or may be again supplied with cold sulfite solution. In this manner I provide against the separation of the calcium monosulfite from sulfite solutions in the digesters, owing to the fact that the sulfite solution is not heated therein from a normal temperature to the boiling-point, during which the monosulfite is chiefly formed, but said solution is supplied to the digester at that or even a higher temperature, so that a sufficient pressure can be maintained within the digesters to prevent the formation of calcium monosulfite. On the other hand, I also utilize the calcium monosulfite, together with the sulfurous-acid gases separated during the heating of the sulfite solutions, by combining the same to form a sulfite solution.

Having thus described my invention, What I claim as new therein, and desire to secure by Letters Patent, is-

1. In the manufacture of cellulose by the sulfite process, the mode of preventing the formation of monosulfite of calcium in the di gesters during the heating of the sulfite solution from a normal to the required temperature, which consists in heating the solution in a separate vessel, separating therefrom the monosulfite of calcium formed during such heating, and introducing the hot solution into the digester, substantially as set forth.

2. In the manufacture of cellulose by the sulfite process, the mode of preventing the formation of monosulfite of calcium in the digesters during the heating of. the sulfite solusame as a solvent for the separated nionosul- I tion from a normalto the required temperafite, substantially as set forth. IO

ture, which consists in heating the solution In testimony whereof I affix my signature in a separate vessel, separating therefrom the in presence of two Witnesses.

5 monosulfite of calcium formed during such CARL KELLNER.

heating, introducing the hot solution into the Witnesses: digester, collecting and condensing the sul- JULIUS GoLDscHMIDT,

' furous-acid gases evolved and utilizing the A. SGHLESSING.

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