• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    1452710 Bleaching wood pulp A AHLSTROM OSAKEYHTIO 13 Dec 1974 [20 Dec 1973] 54038/74 Heading DIP A foamed suspension of wood pulp is bleached to remove lignine by treating with alkali solution and oxidising gas at elevated temperature and pressure. The foam is stabilised with 1 kg/ton of pulp of a foaming agent (a polyoxyalkylene-condensate, dodecylbenzene sulphonate, octylphenoxypolyethoxy ethanol or black liquor. The oxidising gas may be oxygen, air, ozone, chlorine, chlorine dioxide or mixtures thereof. Pulp is digested at 1 and washed to remove most of the black liquor. The pulp, oxygen gas and foaming agent are mixed at 3 and sodium hydroxide solution, oxygen and steam added to reactor 8. A pressure reducing valve may be situated between mixer 3 and reactor 8 to expand the bubbles in the foam. The amount of pulp in the foam is up to 15% by wt., e.g. 8 or 10%. The sodium hydroxide may comprise 6% by weight. Specified reactor conditions are temperature 90 or 110‹C, pressure 4 atmospheres for 10 to 30 minutes. The bleached pulp is degassified at 11 and washed at 10. Kappa valves of 14 to 16.5 are obtained. In the embodiment of Fig. 2, not shown the sodium hydroxide and the foaming agent are applied to the pulp simultaneously and then the oxygen is applied.
    公开号:SU850019A3
    申请号:SU742090807
    申请日:1974-12-19
    公开日:1981-07-23
    发明作者:Викинг Сандман Фрей
    申请人:А.Альстрем Осакейтие (Фирма)；
    IPC主号:
    专利说明:

    The invention relates to a method for bleaching cellulose with an oxidizing gas, in particular oxygen in a slit plant, especially when producing a pulp by the sulphate method. Until now, the bleaching of pulp with oxygen was usually carried out by the way that, after washing, almost all the liquid, which between the fibers, was squeezed out, after which the concentration of the pulp was close to 30%. After that, the pulp was mixed with a certain amount of alkali (NaOH solution) of the necessary dL of bleaching, 6 as a result of which pulp concentrations decreased to 25%. Oxygen bleaching is a process that, by means of alkali, water, heat and oxygen, attempts to remove lignin from cellulose fibers. The amount of reagent a (Oij, llaOH) transferred to. a fiber that is directly proportional to the area of the phase surface (the surface of fluid transfer to the fiber), which can be maximally external to the fiber of the fiber, in this case it is assumed that the hair is separated from each other. If the fibers flocculate together, the total contact surface of the fibers becomes Shorter and the required reaction time for removing lignin from the fibers inside the flocculated sludge (flakes) is increased. As a result, there is a perebelka fibers on the outer surface of the flakes, where even fibers: and thus the bleaching of the fibers as a whole has been carried out unevenly. When there is a month of separation of the fibers from each other, uniform bleaching of all the fibers takes place. . A pulp with a high concentration of fibers is very difficult to process, namely, to mix the required amount of alkali with it, since when mixing, the intestine is unevenly distributed. It is also difficult to transport such pulp to the reactor. When using currently known methods, it is impossible to feed it into a large capacity tank and another form; rye flakes. The known method of oxygen bleaching requires a long reaction time, which leads to the need to increase the size of the reactor. Internal and external fibers in the flakes acquire different strengths of viscosity. With an uneven distribution of alkali, this leads to the fact that in some places the desired ret share does not pass to the end. The amount of oxygen required to remove the lignin from cellulose fibers is 1-1.5% by weight of pulp. A 1 m reactor contains approximately 100 kg of wet, loose pulp, i.e. at a fiber concentration of 25% - 25 kg of dry pulp. If the reaction takes place at a pressure of 10 kg / cm, approximately 10 kg of oxygen is required, which is approximately 30 times the required amount. Therefore, the reaction takes place with a very large excess of oxygen. The closest to the proposed technical essence is the cellulose bleaching assembly, predominantly molecular oxygen in an alkaline medium, according to which surfactants are additionally added to the pulp. The addition of surfactants improves the wetting of cellulose with alkali and increases the penetration of alkali and oxygen dissolved in it into the fibers 1. However, this method is not without all the drawbacks noted. .. The purpose of the invention is to eliminate the drawbacks of the known methods. The goal is achieved by the fact that alkaline water-cellulose pulp with a cellulose concentration of 615% is mixed in the presence of an oxidizing gas, in particular, oxygen and a surfactant to form a stable foam. In the implementation of the proposed method, surfactants the formation of oxygen-containing bubbles. When oxygen disperses among the fibers in the form of bubbles, a large contact surface between the oxygen and the fibrous material is created. The method allows the pulp to be mixed with as much oxygen as is required for bleaching (delignification). Since the fibers are well dispersed and favorable conditions are created for the transfer of oxygen into the fibers, the process is quick and gives even results,. The implementation of the sponge allows to obtain a low kappa number, characterizing the residual lignin content in the pulp, while the viscosity remains at a constant level. In the process, either the liquor remaining in the pulp as a result of prior bleaching operations and / or synthetic supereactive substances, such as polyoxyalkylene condensate, dodecylbenzenesulfonate and octylphenoxypolyethosiethanol, can be used as surfactants. Until now, pulp production has sought to prevent the formation of foam as an undesirable phenomenon. Because of this, the liquor was carefully removed from the pulp. In the proposed method, the foam is used to scatter fibers. In addition, foam facilitates pulp transport. Instead of oxygen, air or other gases, for example, ozone, C l, j, Clj + C10,;, or a mixture of gases can be used. In the proposed method, the reaction time can be significantly reduced. It is only 10-20 minutes compared with 30-60 minutes in the known methods. Due to this, the capacity of the bleaching reactor can be significantly reduced. Example. The experimental reactor is filled with pulp, saturated with oxygen and heated with steam, after which the alkali solution is passed. through the pulp. In another case, under the same conditions, bleaching of pulp containing 1% of Teapola (trademark of Shell), a synthetic detergent is carried out, foaming is performed with a mixer. . Before testing, the pulp has the following parameters: ES 29.3; 7; 1086; whiteness 26.5%. After treatment with NaOH solution under the following conditions: Alkali load,% 6 Pressure, atm4 Temperature, s110 Consistency of pulp,% 8 Reaction time, min 15 Pulp has the following parameters: Test 1 Test 2 with foam without foam, 16.5 C 22, 5 g 890. H 985 Whiteness,% 35.7 Whiteness,% 31.1 It is difficult to obtain in the processing method without foam the CG 20 parameter without increasing the consistency of the pulp to a value exceeding 10%. With an increase in the consistency of the pulp, the whitening is uneven. In tests without foam with an alkali load of more than 10% and under the same conditions as in tests of example 1, the following results: without foam 21.2) {, 900; whiteness 31.3%. Example 2 Sulfate pulp containing 1% Theapol is bleached in a reactor. The density of the cellulose layer is 30 cm. During the treatment with oxygen | m, a solution of NaOH is passed through the cellulose,
    The bleaching of a part of the pulp is done in foam mode, the other part is bleached without the formation of foam.
    Before oxygen treatment 9 $ 26.3 g 1049,
     After processing, the results obtained are presented in the table.
    . The results show that the bleaching of cellulose with an oxidizing gas
    in the presence of alkali and surfactant allows to obtain a positive result only if the process takes place in the foam mode,
    权利要求:
    Claims (1)
    [1]
    Invention Formula
    A method of bleaching cellulose with an oxidizing gas in a water-alkaline medium in the presence of surfactants at elevated temperature and pressure, characterized in that, in order to intensify the process and uniform bleaching of cellulose, an alkaline pulp with water concentration of 6-15% is mixed in the presence of an oxidizing gas and surfactant to form a stable foam.
    (Sources of information taken into account during exgi-resti
    1, USSR Copyright Certificate No. 348664, cl. D 21 C 9/10, published. 1971 (prototype).
    类似技术:
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    同族专利:
    公开号 | 公开日
    GB1452710A|1976-10-13|
    BR7410652D0|1975-09-02|
    FR2255419B1|1979-06-01|
    FR2255419A1|1975-07-18|
    DE2460144B2|1977-03-03|
    SE7317221L|1975-06-23|
    NO142128C|1980-07-02|
    SE390549B|1976-12-27|
    JPS5094202A|1975-07-26|
    CA1065105A|1979-10-30|
    ZA747918B|1975-12-31|
    SE390549C|1985-10-17|
    JPS524643B2|1977-02-05|
    FI52878B|1977-08-31|
    NO142128B|1980-03-24|
    FI370274A|1975-06-21|
    IT1027773B|1978-12-20|
    NO744609L|1975-07-14|
    FI52878C|1987-09-24|
    DE2460144A1|1975-07-03|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JPS563214Y2|1978-05-15|1981-01-24|
    US4209359A|1978-10-23|1980-06-24|International Paper Company|Process for removing residual oxygen from oxygen-bleached pulp|
    SE462919B|1979-05-11|1990-09-17|Sunds Defibrator Ind Ab|PROCEDURE TO PERFORM ALKALIE EXTRACTION OF CELLULOSAMASS IN THE PRESENCE OF ACID|
    US4574032A|1979-10-15|1986-03-04|Westvaco Corporation|Process for delignification of lignocellulosic material in the presence of anthraquinone in solution with white and black liquors|
    SE452896B|1985-01-24|1987-12-21|Aga Ab|METHOD OF TREATING CELLULOSAMASSOR|
    SE460202B|1987-03-13|1989-09-18|Aga Ab|SEATED AS TREATMENT OF A MATERIAL WITH A GAS IN A SCIENCE|
    FI89516B|1989-05-10|1993-06-30|Ahlstroem Oy|Foerfarande Foer blekning av cellulosamassa med Otson|
    US5460696A|1993-08-12|1995-10-24|The Boc Group, Inc.|Oxygen delignification method incorporating wood pulp mixing apparatus|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE7317221A|SE390549C|1973-12-20|1973-12-20|SET TO BLOW CELLULOSIC MATERIAL WITH ACID OR FREE ACID CONTAINING GAS IN ALKALIC ENVIRONMENT|
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