US2202231A - Process for the carbonization of - Google Patents

Description

May 28, 1940. 'r. RE-ICHERT 2,202,231

PROCESS FOR THE CARBONIZATION OF WOOD AND SIMILAR MATERIALS Filed March 11, 1938 G175 OUTLET SQ g. OXYGEN-FREE G445 INLET G55 OUTLET I gwua/wtob THEOPH/L 17E 619E6 7,-

Patented Me; 28, 1940 2,202,231

PROCESS FOR THE CARBONIZATION OF WOOD AND SIMILAR MATERIALS Theophil Reichert, Brilon Wald, Germany, as-

signor, by mesne assignments, to Chemical Marketing Company Inc.,' New York, N. Y.

Application March 11, 1938, Serial No. 195,415 In Germany March 13, 1937 3 Claims. (01. 202-15) The invention relates to a process for the carundesirable. This speed should not exceed about bonization of wood and similar materials. It 50 cm. per second, and advantageously should especially relates to that type of carbonization not exceed 20 cm. per second. in which all of the heat is supplied to the wood By maintaining the speed thus within a range 5 by heating gases, and no other heating of the of 1 to 50 cm. per second, it is possible to obtain 5 wood is provided. high yields under conditions such that separation Such procedures have presented certain difilof the distillation products is easily possible. culties since the large amounts of gas used make Even predried wood can be thus treated with it difflcult to condense or wash out the distillaexcellent results. In carrying out the operation,

tion products. Where attempts have been made all that is necessary is to provide a number oi 10 to reduce the amount of s, ver at and thermometers at diiferent heights in the retort, a e io in yield have generally resultedand to vary the speed of the circulating gases in The P e invention Provides a manner of accordance with the indications of these theriz ns o S0 85 to Obtain high yields mometers so that the temperatures in the upper while utilizing a relatively small amount of cirlayers are not less t t t, i th carboniza- -15 culating gases so that it is easy to recover the t zmm distillation products of the wood. Example 1 Suitable retorts for use in the process herein disclosed are shown in the drawing. Fig. 1 shows An up sht a ted carbonization retort -10 a retort with an inclination of 60 for the upper with a capaclty of approxlmately 100 cubic wall and 4 for the lower n. Fig 2 shows 55 ters was filled with about 40 cubic meters of wood for the upper wall and 45 for the lower wa1l a moisture COntEnt Of 22%- Hot gases Were In order to carry out t process, it has been introduced at the top of the retort and passed found that the most important feature is the downwardly therethrough. these a es when inlinear speed of movement of the circulating gas having a temperature of 450 C. to 500 as it passes through the wood, and by suit 1 C. The gases were introduced at a rate of about 2 regulation of this linear speed improved results t0 3 p cond, and his rate was mainmaybe obtained regardless of the volume of cartained in such a manner by the observation Of bonization gas per unit of wood passing through thermometers that no temperature diiferences the retort. By suitable adjustment of the linear occurred in the various zones. Carbonization be- 30 speed we havefound it possible to carry out the gan promptly and was completed without percarbonization under the best conditions, regardmitting the operat to st p- Du th a n less of the moisture content of the wood. For period of the carbonization distillation products this purpose it is important that the linear speed escaped at the lower part of the retort at temshould lie within a certain range. peratures between 60 and 150 C. The yield per 35 In the ordinary carbonization of wood by cubic meterof wood was as follows: heated circulating gases the temperature in the I Kilogram carbonization zone, which gradually moves down- Acetic acid 43 to 44 wardly through the mass of wood during the car- Wood alcohol 145 bonization process, is higher than the tempera- Wood t I 639 so ture of the previously carbonized layers above Charcoal 200 the carbonization zone. This is true at very low u arspeeds of t circulating gases, If t The charcoal was uniformly charred throughout. rate of circulation is increased, it will be found Various gases may be used as heating ga 45 that at a certain point the temperature excess Such as t on gases from furnaces or the 45 of the carbonization layer over the upper layers like exhaust Eases te mbus on endisappears. When this point is reached, decreases gines. Also gases produced by the burning of in yield are avoided, and an economical process liquid or dust-like fuels may be utilized as heating is thereby possible. In other words, according gases. Preferably the combustible gases obtained 5 to the invention it is important that the linear from the carbonization are used, partly as cirspeed of the circulating gases should be high culating gases, while another part of these disenough to prevent a greater temperature in the tillation products are burned for heating the circarbonization zone than in the zones thereabove. culating gases. Flushing gases may also be used 0n the other hand, the use of too high a speed as a heat carrier if the temperatures of the carat the ordinary temperature and pressures is bonization material are maintained at least as 55 high as 500 C., and preferably between 550 C. and 750 C.

The operation of the process was not obvious since it was to be expected that the exothermic reaction would occur to an increased degree under such conditions. It was furthermore feared that the surfaces of the pieces being carbonized would be so unfavorably influenced by the strong carbonization reaction that proper carbonization would be impossible. Furthermore, a breaking up of the carbonization material was to be expected which would produce a considerable decrease in the value of the charcoal obtained. Also, and most important, such a process would apparently produce a decrease in the yield of the distillation products which are very sensitive to higher temperature, especially in the presence of a catalytic material such as charcoal. However, according to the invention, noneof these results arises, but on the contrary, a high yield is obtained.

Furthermore, since the carbonization can be carried out more quickly the apparatus in which it is carried out may be used oftener. The process is applicable to wood, lignin, peat or other raw materials of vegetable origin.

Example 2 A heat-insulated carbonization retort with a capacity of 100 cm. was filled with wood having a moisture content of 20.5%. Carbonization gas from a preceding operation was heated in a superheater and passed downwardly through the material so that it was heated to from 550 C. to 600 C. The linear speed of the heating gases was kept at 1 to 2 cm. per second. The distillation products were freed in condensers from tar, wood, vinegar and the like, and in washing towers from. wood alcohol. The combustible gases remaining were partly recirculated, and partly burned for heating the recirculating gases. The

yields per cubic meter were as follows:

Kilograms Acetic acid "44 to 45 Wood alcohol- 15 Wood tar--- 63.5

Charcoal 200 these retorts cannot be completely fllled so that spaces occur therein which trap the'gases and cause improper circulation. This prevents the constant movement of the gas at the desired velocity and thus makes it diillcult to maintain the temperature equal in the carbonizing layer and the layers thereabove. According to the present invention such a disadvantage is avoided by making the upper part of theretort in the form of a frustum, for example, a'conicalfrustum, the upwardly converging wall of which forms with the horizontal an angle of at least and preferably and Such retorts can be filled uniformly and completely with wood or other carbonization material. As shown in Fig. 1, the top part of theupper section may be in the shape of a frustum of a cone. However, as shown in Fig. 2, this upper part may be also in the form of a curved surface, such as a spherical segment, a paraboloid and the like. Various other shapes may be provided as long as the walls where they meet the vertical walls form the proper angle.

It has also been found that improved results can be obtained in my process if the lower downwardly converging walls of the retort are given a suitable angle, preferably an angle of 40 to 50 with the horizontal. Such a shape makes it possible for the material in the retort to slide out completely when the door in the bottom is opened to permit the removal of the charcoal.

While I have described herein some embodiments of my invention, I wish it to be understood that I do not wish to limit myself thereby except within the scope of the appended claims.

I claim:

1. A process for carbonizing cellulosic material of vegetable origin to produce high yields of acetic acid.and alcohol, which comprises filling a retort the upper portion of the walls of which forms an upwardly converging angle of between 50 and 65 with the horizontal with such material, and passing hot oxygen-free gases downwardly through such material at a velocity of below 50 cm. per second, the velocity being so regulated that the temperature in the carbonization zone is not greater than that in the zones thereabove, and the temperature of the material being carbonized being maintained between about 500 C. and 750 C.

2. In a process as claimed in claim 1, the lower walls of said retort forming a downwardly converging angle of from 40 to 50 with the horizontal.

3. A process as claimed in claim 1, in which said velocity does not exceed 20 cm. per second.

THEOPHlL REICHERT.

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