US1137255A - Process of and apparatus for the destructive distillation of wood. - Google Patents

Description

A. CAMERON.

PROCESS OF AND APPARATUS FOR THE DESTRUCTIVE DISTIL LATION 0F WOOD.

APPLICATION FILED SEPT- 26, 1913.

1,137,255. Patented Apr. 27, 1915.

3 SHEETS-SHEET I- A. CAMERON.

PROCESS OF AND APPARATUS FOR THE DESTRUCTIVE DISTILLATION 0F WOOD.

APPLICATION FILED SEPT. 26, 1913.

1 1 37,255. Patented Apr. 27, 1915.

3 SHEETSSHEET 2- A. CAMERON. PROCESS OF AND APPARATUS FOR THE DESTRUCTIVE DISTILLATION 0F WOOD.

. APPLICATION FILED SEPT. 26, 1913. 1 ,137,255, Patented Apr. 27, 1915.

v a SHEETS-SHEET a.

ALEXANDER CAMERON, OF EAST JORDAN, MICHIGAN.

RBOCESS OF AND APPARATUS FOR THE DESTRUCTIVE DISTILLATION OF WOOD.

Specification of Letters Patent.

Patented Apr. 2'7, 1915.

Application filed September 26, 1913. Serial No. 791,891.

To all whom it may concern Be it known that I, ALEXANDER CAMERON, a citizen of the Dominion of Canada, residing at East Jordan, in the county of Charlevoix and State of Michigan, have invented a certain new and Improved Process of and Apparatus for the Destructive Distillat on of Wood, of which the following is a specification.

This invention relates to an improved process of and apparatus for the destructive distillation of wood, and it has for its salient objects to provide for the recovery of a larger percentage of wood alcohol, acetate of lime and other by-products; to provide for the carrying out of the process to-completion at a markedly lower temperature and with equal rapidity, or even more rapidly than in accordance with the best practice heretofore known; to effect a corresponding economy of fuel; toeflect a very large saving in the way of malntenance by reason of the much lower temperature at which the process is conducted; to greatly shorten the len h of time required for cooling the resulting charcoal to a condition in which it may be safel to insure a more uni orm and certain reduction of all parts of the wood to charcoal; and in eneral to provide an improved process an apparatus of the character referred to.

The invention will being had to the accompanying drawings illustrating suitable apparatus for carrying the process into effect, and in which drawings, Figure 1 is a view partly in elevation and partly in section, showingamain. retort housed in, two cooling retorts and a-single so-called buggy or car arranged in one of the retorts; Fig. 2 is an end elevation of one of the buggies embodying my apparatus imrovements; Fig. 3is a plan view of a buggy;

ig. 4: is aside elevation of an end portion of one of the buggies, showing a charge which has been reduced to charcoal; and Fi 5 is a similar view of an end portion of a buggy partly loaded and ready to be shifted mto the retort.

In the destructive distillation of wood as now practised in the most modern way heretofore' known, the wood, commonly in the shape of cord-wood, is piled into metal buggies or cars of openwork construction, and rolled into a long tubular steel or iron rehandled and shipped;

be readily understood. from the following description, reference'.

tort, which is sealed except for the outlets for vapors and gaseous products of distillation. This retort is arranged above a suitable furnace and is bricked in by surrounding walls. After the destructive distillation has been completed by the furnace heat applied to the retort, the buggy containing the charcoal is removed from the retort and wheeled into a cooling chamber or secondary sealed retort, and allowed to partly cool. Inasmuch as it is found in practice that it requires about twice as long to cool the charge down to a temperature where it can be safely exposed to the outer atmosphere as it does to distill it, it is customary to employ a pair of cooling retorts, a partly cooled charge being transferred from the first cooling retort to the second cooling retort, the

two retorts thus serving to accommodate one distilling retort operating continuously, or ractically so.

ccordlng to the old 'practice,the wood to i be reduced was piled into the crate or openwork box of the buggy until the latter was sufficiently near full, and without any attempt to separate the wood into layers, but simply allowing the entire pile to rest upon the bottom of the box and confined against lateral movement by the sides of the crate. As the process of distillation proceeded, the wood shrunk and settled, becoming more and more compact as the process proceeded, un-

til at the conclusion the charcoal was in the .form-of a comparatively dense mass resting upon the bottom of the car.

.The apparatus shown in the drawings herein is. of a common type heretofore known, except only that the buggies are of modified construction, as will hereinafter appear.

Referring to the drawings, 1 designates as a whole the main or distilling retort, which is arranged within a surroundin brick setting 2, leaving the 'end doors 3 an 4 of theretort exposed, and, for better protection against the weather, arranged within a shed or housing designated as a whole 5. Beneath the retort is arranged a furnace comprising a pair of grates 6, 6 arranged at the respective ends of the furnace, an intervening combustion chamber 7, and an overlying arch 8, which is spaced some distance below the lower side of the retort, as shown clearly in Fig. 1. Over each grate is arranged a fuel inlet-pipe or hopper 9, through .which the grates may .be supplied,

The doors 3 and 4 constitute the end walls of the retort, and are hinged as indicated at 3 and I, so that they may be swung open to admit the buggies.

Track rails 10 are arranged to extend longitudinally through the retort 2, as well as through the cooling retorts or chambers designated as a whole 11 and 12, respectively. The retorts 11 and 12 are in general similar to the retort 1 except that the outside jacketing of brick is omitted.

The distilling retort 1 is provided with one or more outlet pipes 13, which lead to suitable condensing apparatus, not shown.

Now, describing the construction of the buggies, each vehicle is provided with a suitable skeleton base-frame designated as a whole 15, and carried on a pair of wheeled axles 16, the wheels 17 of which are arranged to' traverse the tracks 10 hereinbefore described. The floor of the vehicle is of slatted construction, as shown plainly in Fig. 3; the slats being suitably spaced so as to prevent the charcoal from falling through, while at the same time affording free acccssfor the circulation of air through the door. The sides and ends, designated 18 and 19, are also of slatted construction, being preferably provided with upright slats 20 secured to suitable horizontal strips 21, which are in turn secured-to the corner posts 22 of the box. The slats of the sides and ends are desirably spaced apart more widely than those of the floor, so as to afford i freer circulation of the air and avoid superfluous weight.

T he distinct feature of improvement of the present apparatus resides in providing means whereby the charge of wood is supported in layers so to speak, and prevented from settling down into a single compact mass in the bottom of the buggy. To this end I provide sets of cross bars, severally designated 23, which cross bars are spaced at suitable intervals apart to support the sticks of wood, and eventually come to rest on the horizontal bars 21 of the end walls of the bugg -box. According to the old practice, the wood was piled into the buggies, resting on the bottom, and rising as hi h as was desired. In the use of my present apparatus and in carrying out the improved process herein described, a first layer of wood is piled into the bottom of the boxuntil it rises to a point somewhat above the lower set of end cross-bars 21, whereupon the first set of supporting rods or tubes 23 is inserted so that the several bars or tubes extend through the spaces between the upright slats and rest on top of the wood. The filling in of the wood is then resumed until the pile has risen a short distance above the second set of end cross-bars 21, whereupon a second set of supporting tubes or rods 23 is inserted as before, and

then the remainder of the charge of wood is piled in on top of these. By piling in the wood and inserting the supporting bars in the manner described, I avoid carryin the' entire weight of the upper layers of the wood directly upon the unsupported bars 23; it being obvious that the pieces of wood underneath them and upon which they rest aid in supporting the wood piled in above. \Vhen the distillation takes place, the first stages of the process drive off the free water, thus very greatly reducing the weight of the wood, and at the same time causing it to shrink considerably. Before the wood has shrunk enough to allow the separating rods 23 to descend into bearing with the cross strips 21, the weight of the wood has been greatly reduced, so that the rods are amply strong to support whatever weight comes upon them.

In carrying out my improved process by the use of the apparatus described, I proceed substantially as follows: The retort being hot, a number of buggies loaded with Wood in the manner described are run in to the retort, end to end, and the doors of the retort closed, whereupon the firing is continued to bring about the distillation. The temperature is raised steadily until the vapors of distillation begin to flow freely from the wood, and is then maintained under such control as to insure a continuance of the free flow of vapors. In accordance with the old practice, the temperature was raised steadily from approximately 500 or 550 Fahrenheit (which may be assumed as the temperature at which the retorts would be when the buggies were inserted) until in the course of about four and one-half or five hours the temperature would range well above 800, and often as high as 900. Having reached this temperature of say 850, the firing was so conducted as to maintain the temperature about the same until the distillation was nearly completed; the temperature being allowed to fall perceptibly at about the end of the seventeenth or eighteenth hour. Thereafter the heat of the kiln was in practice found sufiicient to continue the process to a conclusion; the temperature gradually descending so as to approximate 600 at the end of twenty hours.

In accordance with my improved process, the temperature is raised gradually from the time the retort is closed until it reaches approximately 700 Fahrenheit, which will be at the end of about four hours time. At

this time the vapors of distillation begin to run very freely, indeed so great is the evaporation that the temperature within the kiln decreases to a marked extent. In the demonstrative run in which the temperathree hours later the temperature had descended to well below 600, although .an ample flow of vapors had been maintained. From this time, however, it was necessary to increase the fire so as to raise the tem erature, in order to maintain the desired ow, and the temperature had, at the end of the twelfth hour, again risen to about 700. From this point to near the end of the process the temperature remained nearly uniform and slightly above 700; decreasing, of course, when the fires were withdrawn in the last stage of the process.

By making comparative runs under precisely similar conditions as regards apparatus and wood treated, I found that in accordance with my improved process the average temperature was fully 170 lower than under the old process, and that during a long stretch of time in the intermediate part of the process the temperature was approximately 250 below that necessary in the old practice. I also determined that even with these strikingly lower temperatures the charge was completed, 11. e., completely reduced to charcoal, within a period of about twenty hours; this being approximately the same length of time required under the old process. Besides the markedly lower temperature employed in my new process, I found that I recovered a much larger yield of alcohol and of acetate of lime. That is to say; in the demonstrative runs which I have made I secured fully 20% increase of alcohol, and over 32% of increase in the yield of acetate of lime. These results are easily accounted for by the fact that the distillation is effected at markedly lower temperatures. That is to say, the higher the temperature employed, the greater is the percentage of molecular destruction and consequent conversion of the products into permanent gases which cannot be recovered as distillates.

The fact that the process can be conducted at the relatively low temperatures described must, I think, he explained by the arrangement of the charge within the buggies in layers, 71. 6., in such manner that the heat readily permeates all parts of the mass uniformly almost from the very beginning of the process. This uniform distribution of the heat is of great importance not only in protecting certain portions against overheating and consequent loss of yield, but also in bringing about a uniform reduction of the wood to charcoal in a minimum length of time. I have found that with my improved method there is no uncarbonized wood left in the buggy at the end of the process, whereas under the old practice it was very common to find chunks of partially carbonized wood, notwithstanding the process had been conducted at the much higher range of temperatures. This uniform reduction of the wood to charcoal isan item of fieat importance, inasmuch as the charcoal s a strong tendency to ignite when it is exposed to the outer air, which tendency is much stronger if the charcoal is not perfectly carbonized. Moreover, the fact that the charcoal at the conclusion of the process, as conducted in accordance with my improvements, is in the condition of separated layers, insures a much more rapid and uniform cooling down of the charcoal when it is transferred to the cooling retorts, so that on the whole the process is materially shortened, as well as im roved generally.

Itwill be understoo that after the distillation has been completed in the distillation retort, the retort is opened and the buggies transferred to the next cooling retort, the same as in the prior art practice, and after being there partly cooled, againtransferred to the final cooling retort, where the cooling is completed sufiiciently to permit the mass to be exposed to the atmosphere without danger.

It will be understood from the foregoing description that the salient feature of my improvement resides in the discovery that by separating the charge into layers or comparatively small bodies to which the heat has free access, the distillation may be effected at very much lower temperatures without prolonging the time, and with improved results in the way of increased yields, more rapid cooling of the charcoal, etc. It will be understood therefore that the rocess is not limited to the use of thespecific apparatus herein shown and described, although that apparatus is admirably adapted for carrying out the process.

I claim as my invention:

1. The improvement in the art of destructively distilling cord-wood, which consists in arranging the wood in orderly-piled adj aoent superimposed layers, the under side of each upper layer and the upper face of the lower layer being exposed to permit air to circulate in contact with said adjacent side and face, inclosing the charge in a sealed retort, progressively destructively distilling same by the application of controlled supplies of externally applied heat, and progressively effecting a separation of said layers by permitting said layers to shrink in thickness independently during the distillation process in order to form distinct bodies of charcoal with circulation spaces between them.

2. The improvement in the art of destructively distilling cord-wood, which consists in cording the wood in overlying proximate layers having their adjacent surfaces exposed and separated by inchoate circulation spaces, and carried by a common support, inclosing the charge on said support in a sealed retort, progressively distilling the same by the application of controlled supplies of externally applied heat, and effecting progressive separation of said layers and a evelopment of said circulation spaces to an effective value by substantially confining the movement due to shrinkage to the respect'ive layers.

3. In charcoal burning apparatus, the combination of a sealed retort, a plurality of incombustible cross-members adapted to divide the charge of wood into horizontal layers vertically spaced apart from each other, said members at the commencement of the process being in contact with both layers between which they are interposed, and a plurality of opposed supports adapted to engage said cross-members and support said upper layer upon shrinkage of said lower layer during the distillation process.

4. In charcoal burning apparatus, the combination of a sealed retort, a plurality of incombustible cross-members interposed between two horizontal layers of WOOd to be distilled and supported at the commencement of the process by the bottom layer, and a pair of opposed supports adapted to engage said cross-members and to support said members and said upper layers upon shrinkage of the lower layer during the distillation process.

5. In apparatus for destructively distilling wood, the combination of a sealed retort, -a wheeled skeleton car provided with laterally extending supports at two of its opposed sides, and a plurality of detached incombustible cross-members adapted to be interposed between horizontal layers of wood supported on said car and at the commencement of the process adapted to be supported by the lower layer of wood out of contact with said opposed supports, but long enough at each of their ends to project from between said layers and engage said supports upon shrinkage of said lower layer during the distillation process.

6. The improvement in the art of destructively distilling cord-wood, which consists in disposing the wood in a plurality of contiguous superposed distinctly sectionalized bodies having their adjacent surfaces exposed relatively to each other carried by a suitable common portable support, inclosing the charge in a sealed retort, applying heat thereto and utilizing the shrinkage of wood during the distillation process to effect a substantial separation of said bodies of wood and form comparatively large circulation passages between said bodies, and removing the charge into a cooling medium whereby the cooling of said charge is hastened by the previous formation of said circulation spaces.

ALEXANDER CAMERON.

Witnesses:

NELSON CRANDALL, JAY J. TROMBLY.

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