Improved Apparatus for Use in Treating Wood and other Ligneous Matters by Means of Hydrochloric Acid Gas,
Year: 1884

page_text: Improved Apparatus for Use in Treating Wood and other
Ligneous Matters by Means of Hydrochloric Acid Gas, in
do ahtain Claces therefrom
I, ALEXANDER MELVILLE CLARK, of the firm of A. M. and Wm. Clark, of
53, Chancery Lane, in the County of Middlesex, Fellow of the Institute of Patent
Agents, do hereby declare the nature of the said Invention for IMPROVED Apparatus
FOR USE IN TREATING WOOD AND OTHER LIGNEOUS MATTERS BY MEANS OF
HYDROCHLORIC ACID GAS, IN ORDER TO OBTAIN GLUCOSE THEREFROM and in
what inanner the same is to be performed, to be particularly described and
ascertained in and by the following statement :—
This Invention relates to a combination and arrangement of apparatus for the
treatment of wood and other ligneous matters by means of hydrochloric acid gas,
in order to obtain glucose therefrom.
The apparatus of this Invention which is illustrated in the accompanying
Drawings by way of example may be employed in any of the various processes for
the treatment of ligneous inatters by hydrochloric acid gas and more particularly
in the Daugevillé process for converting wood celluloso into fermentable glucose
and alcohol.
The wood after being cut up and impregnated with the necessary quantity of
liquid hydrochloric acid is subjected to the action of hydrochloric acid gas
in the apparatus represented in Figures 1 to 5 which are respectively a central
longitudinal vertical section, a plan and transverse sections on lines A B, C D
and E F of Figure 2.
The apparatus consists of a lead cylinder which is entirely closed and supported
by iron hoops or rings within a rigid wood framing fixed to end castings having
hollow journals A A mounted in suitable bearings,
The hollow journals are lead lined and connect with the cylinder by a lead pipe.
BB are two manholes for charging the cylinder with the material and C is an

page_text: opening closed by a coned plug faced with indiarubber at which the contents are
discharged.
The cylinder having been supplied with the material to be treated, receives very
slow rotary motion by means of the gearing M, the motion being variable and
diminishing towards the close of the operation, by means of speed pulleys on the
driving shaft.
The gas is introduced into the cylinder through the branch pipe T and is
distributed in the interior by the perforated central pipe D which extends the
whole length of the cylinder and is closed at the end d. The air and afterwards
the gas in excess escapes through the opposite journal and branch pipo T' and is
conducted into an adjoining cylinder, but when one cylinder only is employed, the
pipe T is closed and the gas passes out at T into a condenser. The branch T is
for admitting gas from another apparatus during which time the communication by
branch pipe T with the gas producer is cut off.
▲ shower of cold water is caused to fall upon the cylinder during the entire
operation in order to keep the lead cool and carry off the heat evolved by the
condensation and solution of the hydrochloric acid as well as by the reaction as
fast as it is disengaged.
The duration of the operation-is-about fourteen hours, this time being requisite
for the complete-solution of the cellulose. After this time has clapsed, the supply
of gas is cut off, the plug T is removed so as to adinit air, and liquid is introduced
through pipe T for the purpose of washing the cylinder which is rotated for about
half an hour longer the opening C being downwards, the hand wheel v (whose boss
--nets as a nut for the screwed rod of the plug t) is rapidly turned so as to raise the
plug off its seat and discharge the mixture-of-acid-liquid and wood which has been
treated-into-filters which are provided with a false bottom covered with asbestos
cloth for retaining the fine particles. The liquids thus collected-are-conveyed into
depositing vats those of the strangest quality marking 20° to 22º B being treatedl
separately while the weaker liquids serve for washing purposes in-subsequent.
operations.
The next operation is to recover the hydro-chloric acid contained in the strong
washing liquids. For this purpose the liquids are evaporated in vacuo at a low
temperature in the apparatus represented in Figures 6, 7, 8 which show respectively
a vertical section, plan and part horizontal section on line A B. The apparatus
consists of a cylinder having convex ends, the upper one being furnished with a
done. The apparatus may be made entirely of lead or of east or sheet iron lined
with lead. A worm S is placed in the bottom of the cylinder and the steam for
heating, which is generally the exhaust steam from the engines, enters at e, e and
escapes at 8, 8.
Glazed sight holes g, g are provided for watching the course of the
evaporation. At the top of the dome there is an outlet E for the vapours to pass
to the condenser, which consists of an assemblage of tubes F contained between the
two heads G, G. H is the outlet for the condensed vapours; the water used for
condensing enters at L and passes out at M after circulating around the tubes F.
A powerful air pump is connected with pipe K and extracts the air that part of
the condenser, where the condensation is the most perfect. Adjoining the
condenser are two ve-sels connected to the outlet H, for receiving the condensed
liquids. These vessels which also communicate with the air pump are used
alternately; a cock shutting off the one vessel which may be emptied, while the
other is filling. The branches m, m, m, are for putting the casing in communication
with the interior of the apparatus in order to establish the same pressure and thus
avoid the collapsing of the lead chamber. The operation is completed when the
glucose which remains in the apparatus does not contain more than about 7. per
cent. of its weight of acid. The glucose which is of the consistency of molasses is
discharged from the apparatus at P and the operation recommenced. Instead of
having two vessels in connection with the condenser, for receiving the condensed
acid, the entire apparatus might be placed at a suitable height to obtain a

page_text: barometric outflow column by prolonging the pipe H. The hydrochloric acid
recovered is of a strength of 15° B. and is utilised for producing the gas necessary
for acting on the wood in the cylinders previously described in reference to
Figures 1. to 5.
In order to produce this gas hydrochloric acid is caused to fall on to concentrated
sulphuric acid raised to a temperature of 135° C.; from this mixture the whole of
the hydrochloric acid gas disengages and the dilute sulphuric acid is run off for the
purpose of being concentrated for use again for the production of more gas. For
this purpose the two apparatus next described are employed. The apparatus
represented in Figures 9 to 12 is for the production of hydrochloric acid gas and
that represented in Figures 13, 14 and 15 is for the continuous concentration in
vacuo of the dilute sulphuric acid. The apparatus may be constructed entirely of
lead or of cast iron lead lined.
The apparatus for the production of hydrochloric acid gas represented in vertical
section at Figure 9., horizontal section in Figure 10, in elevation in Figure 11. and
plan in Figure 12, consists of a domed cylinder containing an inner cylindrical
chamber A.
The two compartments thus formed contain worms 8, 8¹ and have sight holes
9, 9, 9, at which to watch the progress of the operation.
Above the level of the liquid the lining is not in contact with the iron easing
but sufficient space is left between them for a steam coil D which also encircles the
dome; this coil keeps the lead at a certain temperature and thus prevents the
condensation of hydrochloric acid gas upon the sides of the apparatus.
The apparatus for concentrating the sulphuric acid comprises an evaporating
chamber and a condenser.
An outlet E at the top of the dome communicates between the evaporator and
the condenser. The latter may either be an injection condenser as in Figure 13
or a surface condenser like that shown in Figure before described. fffare
sight holes for watching the progress of the evaporation. S is a heating coil
placed as near the bottom of the evaporator as possible, the steam enters at e and
escapes at 8. O is the connection for the air pump and P is a hanging shield for
preventing the abstraction of the liquid by the pump. The entire apparatus
Figure 13 is placed at a suitable height to obtain a barometric out flow column
through F of the water of condensation. By this means accidents which might bo
caused by the water returning into the boiling sulphuric acid are prevented.
A thermometer is placed at T to indicate the temperature of the acid in the
evaporating chamber. The two apparatus Figures 9 and 13 being charged with a
suitable quantity of sulphuric acid at 58° or over, the acid is heated to 135° in the
disengaging chamber and to from 110° to 120° in the apparatus for concentrating
the sulphuric acid. The hydrochloric acid is introduced in the midst of the
sulphuric acid by the dip pipe ab Figure 9 and whatever may be the degree of
concentration of the hydrochloric acid, the whole of the gas which it contains
instantly becomes disengaged and escapes through the outlet G to the attacking
cylinders before described, after passing through series of pipes or stone-ware
vessels for the purpose of retaining any aqueous vapor which may be carried along
with it. The dilute sulphuric acid overflows at H into the annular space
surrounding the inner compartment A and flows out at K after making such a
circuit as will enable the last traces of the gas to escape. The dilute acid enters
at L into the concentrating apparatus Figure 13. The circulation from one
apparatus to the other in this direction is due to the difference of pressure and is
regulated by a cock. The return of the concentrated sulphuric acid to the gas
producer is effected by a special pump which takes the acid from M Figure 13 and
delivers it at N Figure 9, the speed of said pump being regulated according to the
quantity of hydrochloric acid Howing into the gas producer. The combination of
these two apparatus permits of obtaining a continuous and regular production of
hydrochloric acid gas without waste of the sulphuric acid.

page_text: Having now particularly described and ascertained the nature of the said
Invention, and in what manner the same is to be performed, I declare that what
I claim is:
The employment of the apparatus herein described combined and arranged as
hereinbefore specified and illustrated in the Drawings, for the treatment of ligneous
matters by means of hydrochloric acid gas for the purpose of obtaining glucose
therefrom.