US1942760A - Process for making pulp from fibrous material - Google Patents

Process for making pulp from fibrous material Download PDF

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Publication number
US1942760A
US1942760A US635673A US63567332A US1942760A US 1942760 A US1942760 A US 1942760A US 635673 A US635673 A US 635673A US 63567332 A US63567332 A US 63567332A US 1942760 A US1942760 A US 1942760A
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United States
Prior art keywords
liquor
digester
cooking
gases
wood
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Expired - Lifetime
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US635673A
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English (en)
Inventor
Kreiszler Otto
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American Lurgi Corp
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American Lurgi Corp
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C1/00—Pretreatment of the finely-divided materials before digesting
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C7/00—Digesters
    • D21C7/14—Means for circulating the lye

Definitions

  • This invention relates to a process for making 'pulp from fibrous material.
  • the irregular composition of the liquor resulting from the relic and the re-e nployment of the relieved gases and v liquids, also has an important influence on the length of the cooking process, thereby causing 9o irregular working loads throughout the entire series of operations, including the raising of steam, preparation of the liquor and wood material and so forth. Finally, the relieving of the gas and liquor is attended with special losses of material.
  • the process of the present invention enables these defects to be overcome. It consists in that, although the digester is fully charged with wood at the outset, it is no longer completely filled with liquor, the amount of the latter being reduced approximately by the quantity necessarily removed during the cooking process by the expulsion of liquor and gas, in the method of working hitherto pursued. It has been ascertained that, by operating according to the process of the present invention, the quality of the cellulose does not sufier in any way but, on the contrary, is substantially improved inasmuch as, at the commencement of cooking, such'portions of, the wood as are not covered by the liquor are not subjected to any damage.
  • the preferred method of penetrating with liquor the wood that is exposed in the upper part of the digester before cooking commences consists in pumping the digester full of liquor at the outset. It .is preferable to keep the pump running until the pressure in the digester has risen to about 3 atmospheres, or to a degree corresponding to the normal maximum working pressure of 5 atmospheres or more.
  • the, liquor in excess over the limit according to the present invention is drawn oil, for example from the lower part of the digester without opening the top part of the digester, after which the cooking is commenced.
  • the liquor to be withdrawn prior to cooking may, however, be taken from any other part of the digester, such as at the top or the middle.
  • the requisite pressure drop for the outflow of liquor from the digester can be produced by means of a pump, or the like, or the vacuum set up in'the upper part of the digester through the withdrawal of liquor may be wholly or partially nullified by admitting gases into the digester, preference being naturally given to gases which are favourable for the cooking process, such as sulphur dioxide, relief gases from other 'peratures, such as 125 0.,
  • the first withdrawal of gas commencedat a temperature of 70-80 0.
  • this measure helps to lessen the increase of pressure in the digester, because, under the increased liquid pressure in the lower part of theidigester, larger quantities of gas are cumstance also increases the strength 01 the liquor to a certain extent, thereby naturally facilitating the cooking process.
  • a point that must be regarded as a particular advantage of the invention is that the heat supplied to the digester is solely expended in effecting the cooking process. It will be evident that, in consequence, and because smaller quantities of liquor have to be heated, the heat consumption for each cooking is very favourable. Moreover, under such optimum conditions of the consumption of heat and liquor, all the dig'esters in a mill can be arranged and operated so that each works independently and the (strength of liquor, temperature and pressure) liquors are used, the
  • the return of the gases from the upper part of the digester into the cooking process can be effected by known devices, such as compressors, turbo-blowers or injectors.
  • injectors can be operated, for instance, by the steam which has to be employed for the cooking in any case.
  • the'gas-return pipe can be conin the most favourable manner.
  • the liquor itself can also be circulated. in known manner, either from below upwards, or vice versa, or vertically or laterally from the centre outwards,,and the return of the gases can also be arranged in the same manner. Of course, in all these cases, there is nonecessity for the liquor circulation and the return of the gases to be combined.
  • the circulation of the gases and liquor in the process according to the invention also contributes substantially to maintaining the concentration of sulphur dioxide in the liquor, up to the end of the cooking process, at a level hitherto unattainable by employing initial liquors of the same concentration.
  • the initialliquor contained 4.1% of sulphur dioxidefthe, S01: content of the end liquor still amounted to 2%.
  • the removal of the relief gases can also be considerably accelerated by increasing, with the aid 01' known conveying devices, such as injectors, blowers or compressors, the inherent positive pressure by which the gases are conveyed from the digester that is to be relieved to the point of utilization.
  • the digester can be made ready for the draining ofl of the charge by admitting water or similar liquids and thereby completely displacing the gases present in the digester. In such case no alteration is needed in the conveying device or in the utilization of the gases.
  • the pipe 19, fitted .with the strainer 18 and throttle 20, serves for drawing off liquor from the digester.
  • the gauge 21, fitted with the cooks 22 and 23 serves for inspecting the height of liquor in the digester.
  • 24 is the inlet and 25 the outlet of the digester.
  • Steam can be introduced into the digester through the pipe 26, whilst the pipe 28 can be employed for charging the digester with liquor.
  • These pipes also are provided with throttles, 27 and 29 respectively.
  • the pipe 30, with valve 31, serves to admit water into the digester. Gases can be led out of the digester through the pipe 32, provided with valve 33.
  • the digester 1 with a capacity, for example, of 225 cu. metres, is charged with chips, either by gravity from the chip bin overhead, or by means of a mechanical filling apparatus, the outlet having first been closed.
  • the valve 29 is then opened and liquor is admitted into the digester through the pipe 28, the inlet 24 being left open. when the digester has been completely filled with liquor, and the interstitial until a pressure of, for sample 3 atmospheres, or
  • the valves 20, 22 and 23 are closed, and cooking is commenced by starting the liquor pump 2 and opening the valve 17 in the steam pipe 16.
  • the steam for cooking, or additional steam for that purpose can be admitted into the digester by opening the valve 27 in the pipe 28.
  • the pump 2 draws the liquor in through the intake branches 5 and pipe 4, from the upper part of the digester, and forces it through the pipe 6 and perforated head '7 into the bottom of the digester.
  • the gases collecting in the upper part of the digester are drawn of! through the pipe 9 and injector 8 and are mixed with the circulating liquor in saidinJector and also in the pipe, being more or less completely absorbed by the liquor,
  • the'valve 33 may be opened, to allow gas to escape through the pipe 32 and relieve the digester pressure,
  • This pipe 32 also serves for carrying oif the gases after the cooking is finished. During this latter relieving of the gases, water can be admitted into the digester thi'ough the pipe 30. when the digester pressure has fallen to a sufflcient extent, the pulp is discharged through the outlet 25, and the digester is temperature for a fresh charge.
  • FIG. 3 shows the course of the to the invention.
  • a process for making pulp from fibrous material with sulphite liquor which comprises charging the digester before cooking begins with a quantity of liquor which is smaller than usual by the amount that would otherwise have to be removed by relieving and blowing-oil, without reducing the quantity of wood charged into the digester, and irrigating the wood above the level of the liquor with cooking liquor and thereupon carrying out the cooking in the usual manner.
  • a process for making pulp from fibrous material with sulphite liquor which comprises charging the digesterfbefore cooking begins with a quantity of liquor which is smaller than usual by the amount that would otherwise have to be removed byrelieving and blowing-oil, without reducing the quantity of wood charged into the digester, and irrigating the wood above the level of the liquor with cooking liquor at the commencement of the cooking process.
  • a process for making pulp from fibrous material with sulphite liquors which comprises filling the digester full of both wood and cooking liquor before cooking commences, drawing off so much oi the liquor as would otherwise have to be removed by relieving and blowing-on, thereupon commencing cooking and circulating the liquor and returning thagases from the upper part of the digester into the cooking liquor.
  • a process for making pulp from fibrous material with sulphite liquors which comprises filling the digester full oil both wood and cooking liquor before cooking commences, subjecting the liquor to pressure, drawing off so much of the liquor as would otherwise have to be removed by relieving andblowing-ofl, thereupon commencing cooking and circulating the liquor and returning the gases from the upper part of the digester into the cooking liquor.
  • a process for making pulp from fibrous maerial with sulphite liquors which comprises filling the digester full of both wood and cooking liquor before cooking commences, subjecting the liquor to a pressure which can be increased to the maximum permissible working pressure of the digester, drawing off so much of the liquor as would otherwise have to be removed by relieving and blowing-oil, thereupon. commencing cooking and circulating the liquor and returning pressure p in the digester the gases from the upper .part of the digester into the cooking liquor.
  • a process for making pulp from fibrous material with sulphite liquors which comprises filling the digester full of both wood and cooking 'material with sulphite liquors which comprises filling the digester full of both wood and weak cooking liquor before cookingcommences, drawlog off so-much of the liquor as would otherwise have to be removed by relieving and blowingofi', thereupon commencing cooking and circulating the liquor and returning the gases from the upper part of the digester into the cooking liquor.
  • a process for making pulp from fibrous material with sulphite liquors which comprises filling the digester full of both wood and cooking liquor containing 2 to 4% sulphur dioxide before cooking commences, drawing ofl so much of the liquor as would otherwise have to be removed by relieving and blowing-off, thereupon commencing cooking and circulating the liquor and returning the gases from the upper part of the digester into the cooking liquor.
  • a process for making pulp from fibrous material with sulphite liquors which comprises filling the digester full of both wood and weak digester liquor, drawing ofi so much of the liquor as would otherwise have to be removed by relieving and blowing-off, thereupon commencing cooking at a low maximum cooking temperature and circulating the liquid without circulating the gases.
  • a process for making pulp from fibrous material with sulphite liquors which comprises filling the digester full of both wood and strong cooking liquor, drawing on so much of the liquor as would otherwise have to be removed by relieving and blowing-off, thereupon commencing cooking and circulating the liquor and only returning the gases from the upper part of the digester into the cooking liquor when the temperafure reaches 120-130 C.
  • Process according to claim 11 distinguished by the fact that the cooker first is filled entirely before the cooking operation both with the material to be cooked and with the liquor, and then only is the reduced liquor filling produced before the cooking begins.
  • Process according to claim 13 distinguished by the fact that the cooker first is filled entirely before the cooking operation both with the material to be cooked and with the liquor, the latter being under pressure, andthen only is the reduced liquor filling produced with production of a partial vacuum in the upper cooker chamber filled with material to be cooked, before the cooking begins.
  • Process according to claim 11 distinguished by the returning of expelled gases and of the liquor from the upper part into the lower part of thecookingchamber by a pump inwhich both the gas and the liquor lines are arranged inside the cooker and the two are connected together by a jet apparatus fed by the liquor pipe, whereby the gases are drawn oii from the space above the liquor level and moved with the aid of the jet apparatus fed by the liquor pipe inside OTTO EISSLER.

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  • Paper (AREA)
US635673A 1932-02-17 1932-09-30 Process for making pulp from fibrous material Expired - Lifetime US1942760A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1942760X 1932-02-17

Publications (1)

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US1942760A true US1942760A (en) 1934-01-09

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US (1) US1942760A (enrdf_load_stackoverflow)
FR (1) FR750769A (enrdf_load_stackoverflow)
NL (1) NL39617C (enrdf_load_stackoverflow)

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Publication number Publication date
FR750769A (fr) 1933-08-18
NL39617C (enrdf_load_stackoverflow)

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