US1581671A - Production of pulp and other products from wood - Google Patents

Description

No Drawing.

Patented Apr. 20, 1926.

UNITED STATES PATENT OFFICE.

L INN BRADLEY, or MONTCLAIR, NEW JERSEY, AND EDWARD 2. 11mm, on NEW YORK, N. Y. 1

PRODUCTION OF PULP AND OTHER IFRODUCTS FROM WQOD.

To all whom it may concern:

Be it known that we, LINN BRADLEY and EDWARD P. McKnnrE, citizens of the United States, residing at Montclair, county of Essex, State of New Jersey, and New York city, New York County, State of New York,

respectively, have invented certain new and useful Improvements in Production of Pulp and Other Products from Wood; and wedo 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.

This invention relates to improvements in the treatment of wood for the production of pulp and fermentable sugars therefrom.

In the treatment of wood for the production of fermentable sugars, it has heretofore been proposed to subject the wood to treatment with dilute acid under pressure and at an elevated temperature in order to convert as much as possible of the wood 1nto fermentable sugars. When wood is treated in this way, the wood is so profoundly moditied and changed by the acid treatment that it is no longer of value for the production of pulp, or is of relatively little value for that purpose. Y

When wood is subjected to the ordinary chemical pulp processes, the amount of sugar recovered from the wood is relatively small, and the amount of sugar recovered-is in a dilute solution. For example, in the waste liquor of the acid sulphite pulp process, the sugar content of the waste liquor will only be around 1 or 2%; and the fermentation of this liquor for the production of alcohol from its sugar content is a correspondingly difiicult process requiring the handling of large Volumes of liquor in proportion to the amount of alcohol recoverable therefrom. v

.of pulp therefrom; so that we obtain both a large and considerable amount of fermentable sugar from the wood and substantially a normal yield of ood quality pulp.

The process of t e present inventlon is a I Application filed November 3, 1921. Serial- No. 512,633.

two step or a two-stage process, the first' step or stagewof which comprises treating the wood with a liquor which will break down a part of the wood into fermentable sugar without injuringits pulping properties, and Which will at the same time prepare the wood for the pulp-making process and make the treated wood better adapted and more valuable .for treatment 'in the pulp process. The second step or stage of the process is then carried out upon the preliminary treat ed wood for the production of pulp there from. The fermentable sugars and other extracted constituents are thus obtained as\ a preliminary and separate product of the process; while the wood pulp is obtained as a prlmary final product of the process. Owing to the preliminary treatment of the wood the subsequent pulp-making process is improved as Wlll appear from the further. description of the invention.

vOur investigations of wood indicate that, in addition to the fibres which form the pulp, when the wood is subjected to a chemical pulp process, the wood contains products which are apparently of an intermejury to the pulping properties of the wood,

and even with improvement in the pulpmaking properties. It may be that the constituents of the wood, or certain of such constituents, are. in process of transforma tion from simple sugars (such as are sometimes found in abundance in the sap of certain woods) into the more complex cellulose of the fibres; and that these intermediate products can be broken down or degenerated into simple molecules of fermentable sugars without objectionable injury to the valuable fibres themselves which form the pulp.

Our investigations indicate further that a higher yield of sugar is obtainable from old wood or-wood which has been out for some time than from sound wood freshly cut. It may be in the changes which take place in wood afterthe wood is cut, and particularly where the wood is not thoroughly dried and begins to undergo the slow process ofbreaking down or disintegrating, that the cellulose of the wood breaks downslowly into less complex constitu nts which a higher yield of sugars than freshly cut sound woods.

Our investigations indicate further thatthe constituents which yield fermentable sugars are not directly soluble in water, or are soluble in water only to a limlted extent; but we have found that if the wood is temperatures, its value for pulp-making pur-' poses is lowered. The preliminary treatment accordingly should be regulated as to time, or as to temperature, degree of acidity and time, so as to avoidobjectionable in ury to the pulping properties of the wood, while still breaking down the wood to give a substantial yield of fermentable sugars therefrom.

In preparing the wood for the process it can be chipped in much the same way as for the common chemical pulp making processes. The wood chips can then be treated, for example, with a dilute solution of hydrochloric acid, containing about 1% of hydrochloric acid, and using a sufficient amount of "the liquor to just cover the chips, say 5 to 6 times as much water as chips. For best results the temperature should be kept'well below boiling and preferably over 100 F.', say between 100 F. and 180 F. The liquor can be' tested for its content of-reduc1ng sugars and the treated chips can Qalso be tested for their pulp-making properties, and it can thus be readily ascertained when the sugars have been increasedwlthout injury to the pulp-making properties of the chips.

The solution of su ars and other soluble z constitue'nts-thus produced, by treatment of a single charge of the chips, can be used for treating .a further charge of chips, and

' the sugar-content of the solution thereby increased; and successive charges of chips can be treated -;by the same liquor until a relatively vhigh contentof-fermentable sugars is obtained therein. The treatment-of the chips may, for example, be carried out on the counter-current principle, so that the same char e ofIchips will be subjected to successive iquorswhich may beof the same orof varying composition so that the wood will be progressively acted upon and the amount of fermentable sugars in the l quors 'n'ogressively increased.

During the treatment of the'wood, organic acids may be set free or formed from the wood, and these organic acids may similarly zation of the acidity if necessary or desired,

and made into a molasses or into a thick syrup which can be used, for example, as a stock food, or as an ingredient of stock feed, by compounding with other ingredients such as oil cake or meal from grains, etc.

The sugar solution can also be subjected to fermentation for the production of alcohol therefrom. The solution may thus be neutralized, in case its acidity is too high for fermentation, and yeast then added, to-' gether with suitable yeast food, and the solution subjected to fermentation for a sufiicient time in order as much as possible to convert the fermentable sugars into alcohol. The alcohol can then be removed by distillation and the residual liquor can then be concentrated and used as a stock food or as an ingredient of stock feed.

The wood chips which have been subjected to the preliminary treatment will be of a uniform moisture content and will be already saturated with water or with the dilute acid liquor so that they are less apt to The wood chips can be cooked by the common chemlcal processes, such as the acid sulphite process, the soda process, and the so-called sulphate process. Owingto the preliminary removal of a part of the wood substance by the preliminary treatment, the amount of cooking material required can be somewhat reduced,.and the cooking oper-. ation can be more easily carried out. The residual liquors from the pulp-making process will also be materially improved and will differ in character from the usual residual liquors in that they will, be .free from, ,or materially lower in, fermentable sugars and constituents removed. by the preliminary 4 and characteristic properties is obtained, as

well as a residual liquor of characteristic properties. So also, even where the charge of wood in the digester is larger than can be satisfactorily treated by the soda process (owing to the limits of concentration of caustic soda which can be used) the chips can nevertheless be satisfactorily treated by the sodium sulphite liquor inasmuch as the strength of the cooking liquor can be increased to an extent which will completely cook the chips even with a greatly increased charge of chips in the digester. I

The process of the present invention can be carried out on different kinds of woods both coniferous and deciduous, for example, such woods as spruce, poplar, etc. and woods which, by the ordinary pulp making processes, yield only small amounts of fermentable sugars in the residual liquors, can be utilized as sources of fermentable sugars as.

well as for the production of pulp therefrom. The preliminary treatment of the wood for the recovery of fermentable sugars therefrom may take place in large vats of Wood or concrete; while the pulp-makingprocess may be carried out in the usual pulp digesters. The steam from the blow-pits may be utilized to advantage in heating the water used for the preliminary treatment, for example, by passing this steam through a heat exchanger in heat interchanging relation with the water used for the preliminary treatment.

It will thus be seen that thepresent invention enables wood to be used for the production of pulp therefrom, with advantage to the pulp-making process, and that in addition it enables fermentable sugars to be obtained as a separate product and in a form well adapted for use; and that the treatment of the wood for the recovery of fermentable sugars and for the recovery of pulp are so carried out that the pulp-making properties of, the wood are not destroyed or injured, but rather im roved. The residual liquors will also be 1mproved because of their decreased content of organic matter in solution so that, for example, in the pulpmaking process in which a normal sodium liquor can-be used over again to better advantage in the treatment of further charges of chips for the production of'pulp therefrom. I

Instead of sodium sulphite, potassium sulphiteor a mixture of these two may be used for the production of the cooking liquor of the pulp making process.

We claim: 4 1

'1. The method of treating Wood which comprises subjecting the woodto a preliminary treatment with a hot aqueous acid V liquor to break down and convert a part of the normally water-insoluble wood constituents into fermentable sugars without cooking the Wood or injuring the pulping properties of the wood, separating the fermentable sugars, and subsequently subjecting the wood to a chemical pulpemaking operation.

2. The method of treating wood which comprises subjecting wood chips to treatment with a hot aqueous acid liquor with an aqueous liquor to break down and convert a part of the normally water-insoluble wood constituents into fermentable sugars -without cooking the wood or injurin the pulp-making properties or the wood 0 i s.

3. The method of treating wood whlch comprises subjecting wood chips to treatmentwith a hot aqueous acid liquor to break down and convert a part of the normally water-insoluble wood constituents into fermentablesugars without injuring the pulpmaking properties. -of-the wood "chips and subjecting further charges of the woodchips to treatment with the aqueous liquor until a liquor concentrated in-lfermentable sugars is obtained.

4. The method of treating -=wood-whichcomprises subjecting the wood to a preliminary treatment with a dilute acid liquor to break down and convert a part of the wood into fermentable sugars without cook-: ing the wood or injuring the pulp-making properties of the wood separating the resulting sugar solution from'the wood, and then subjecting the Wood to a chemical pulp making operatlon.

5. The method of treating wood which comprises subjecting the wood to a preliminary treatment to break down and convert a part of the wood into fermentable sugars without injurying the pulping properties of the wood, separating the fermentable sugars, and subsequently cooking the wood with a non-acid cooking liquor consisting essentially of normal alkali-sulphite.

6. The method of treating wood which comprises subjecting wood chips to treatmentwith a hot a ueous liquor at a temperature below the oiling point until normally water-insoluble wood constituents are broken down and converted into fermentable sulphite cooking liquor is used, the cooking sugars without injuring the pulping propertics of the wood, separating the-resulting solution of fermentable sugars, and,subsequently subjecting the wood. to a pulpmaking operation with a non-acid cooking liquor containing sodium sulfite.

7 The method of treating wood which comprises subjecting wood chips to treatment with a hot dilute acid solution containing a small amount of a mineral acid at a temperature between about 100 and 180 F., removing from the Wood chips the re-' sulting solution and. subsequently subjecting the wood chips to a chemical pulp-making' operation.

8. The method of treating wood which ment with a hot dilute acid solution containing a small amount of a. mineral acid at a temperature between. about 100 and 180 F,,'rem0ving from the Wood chips the resulting solution and subsequently subjecting the wood chips to a chemical pulp-making operation with a cooking li nor-con- Eisting essentially of normal so ium sul- In testimony whereof we affix oursignatures.

LINN BRADLEY. EDWARD P. MoKEEFE.

comprises subjecting wood' chips to treat-