The way oxygen delignification of unbleached pulp

 

(57) Abstract:

Usage: in the pulp and paper industry pulp production. The inventive unbleached pulp mass injected alkaline material while reducing the consistency of the pulp to below 10% of the mass. Improve the consistency of the obtained nizkochastotnoi masses up to at least 18% of the mass. Remove the liquid phase and carry oxygen treatment vysokokonkurentnoj pulp. Before you raise the consistency of the pulp nizkobonitetnyh mass combine with alkaline material sufficient for its uniform distribution throughout the fibrous mass. When the oxygen treatment machine vysokokompetentnoe mass, the content of alkaline material at least from 0.8 to 7 wt%, counting on the abs. dry. substance, and the specified amount of alkaline material in generally evenly distributed throughout vysokokonkurentnoj fibrous mass. More than 50% remote liquid phase returns directly to the step of combining with the alkaline material. 10 tab., 1 Il.

The invention relates to a method of processing wood pulp, and more particularly, to a method of oxygen delig the e strength.

The known method of delignification and pulp, including the introduction of unbleached pulp weight of alkaline material to form a consistency 1-15% wt. improving the consistency of the pulp material to 10-45% of the mass. removing the liquid phase, making him the pulp Mat, which is treated with alkali, washed and subjected to an oxygen treatment /1/.

In accordance with the present invention unbleached pulp mass is washed to its original consistency. Then this initial consistency of the pulp is reduced to below about 10 weight. preferably less than 5 weight. getting nizkobonitetnyh mass. The alkaline material is then injected into nizkobonitetnyh mass by combining this nizkochastotnoi mass with such a quantity of alkaline material and thus, in order to achieve a practically uniform distribution of the desired amount of alkaline material throughout the fibrous mass. Such uniform distribution of the alkaline material is sufficient to facilitate improved selectivity of delignification in the process vysokokonkurentnoj oxygen delignification in comparison with that which is achieved when cristou mass or treated with low-consistent mass using only very small amounts of alkali.

To complete processing of the fibrous mass of the alkaline material the consistency of the pulp further increase up to a level of at least approximately 18% receiving vysokokompetentnoe fibrous mass. Stage improve the consistency of the pulp includes pressing or processing by other nizkochastotnoi fibrous mass in order to remove from it pressat containing alkaline material, leaving the desired amount of alkaline material, distributed throughout the fibrous mass.

A certain amount of pressata can be direct deposited in the collection tank so that pressat be able to continuously return or send for recycling directly to the machining stage alkaline material regardless of whether the stage of improving the consistency of periodic or continuous way. All this preset or at least a substantial part thereof, that is more than 50% preferably about 75-95% directly return to the stage nizkochastotnoi processing. The remaining part of pressata can be sent to the apparatus for washing of unbleached pulp or recuperation system to maintain Vodica vysokokonkurentnoj fibrous mass, is at least approximately from 0.8 to 7 weight. in terms of the number of absolutely dry ("AC") of cellulose, more specifically and more often from about 1.5 to 4 weight. for wood southern trees softwoods and from about 1 to 3.8 weight. for wood of firm breeds. Then the fiber is subjected to oxygen delignification, resulting in improved delignification.

The implementation of the present invention allows to simplify the processes of bleaching pulp, which is conducted after vysokokonkurentnoj oxygen delignification of fibrous material treated with an alkaline material. In carrying out such processes use less bleaching chemicals from getting bleached paper products, which has increased strength compared to paper products made in accordance with the usual methods of oxygen delignification vysokokonkurentnoj fibrous mass.

According to another aspect of the embodiment of the proposed method to achieve improved delignification selectivity, which is obvious from the identity data of the content of lignin (i.e. numbers or permanganate numbers) when balaei same parameters for fibrous mass, processed in the usual way. In addition, the embodiment of the method of the present invention enables to obtain a fibrous semi-finished product, which is characterized by a higher degree of whiteness than normal processed by fibrous mass, which are further processed using the same quantities of bleaching chemical.

In accordance with the present invention offers high-quality, high-strength delignification wood pulp Kraft pulp or fibrous masses obtained in the course of conducting other processes of chemical pulping. Preferably the starting material is unbleached pulp mass, which is obtained by cooking wood chips or other fibrous materials in the cooking solution, in particular, through the implementation of the method sulfate pulping or sulfate AO cooking.

In accordance with the invention in the digester serves wood chips and white liquor containing the hydrate of sodium oxide and sodium sulfide. In the digester white liquor is injected in a quantity sufficient for covering practically the whole mass of wood chips. Then the contents of the digester is heated to a temperature and maintained at this tinctions the whole mass of wood chips and almost complete reaction during cooking.

This stage of cooking wood chips usually known as the sulphate method of cooking or sulphate method of cooking, and fibrous mass, which is obtained by implementing this method is called Kraft pulp. Depending on the lignocellulosic starting material results of delignification obtained according to conventional sulfate method of cooking, can be improved with new technology over extended delignification or sulphate AO cooking. Moreover, such techniques are preferable to achieve the highest degree of reduction of the permanganate number of the fibrous mass without compromising strength properties and viscosity of the pulp at the stage of cooking.

In the case of the use of technology sulfate AO cooking the content of anthraquinone in the cooking solution should be at least about 0.01 weight. in terms of speakers weight being defibrinating wood, preferably the content should be in the range of from about 0.02 to 0.1 weight. The use of anthraquinone in the implementation of sulphate cooking contributes significantly to the removal of lignin without undesirable deterioration of valuable strength characteristics of the remaining who are saving on the cost of chemicals, used in bleaching stages that follow the oxygen delignification of pulp.

It is also possible to use more extended delignification, in particular, methods of Keimir MSS, Beloit RDH and superbatch Sands. The implementation of such technology also provides the ability to remove during cooking additional amount of lignin without degrading such desired characteristics as strength remaining pulp.

As a result of work digester black liquor is formed, containing the reaction products by solubilization of lignin together with unbleached cellulose. By stage of cooking is typically followed by washing to remove most of the dissolved organic substances and chemicals process of cooking with the subsequent recycling, as well as the stage of purification of the mass in which the fiber is passed through a sorting unit for removing bundles of fibers that have not been split during the pulping. Then unbleached pulp is sent to the blow tank.

Unbleached pulp that comes out of the blow tank, served in the washing machine, in which the fiber is washed to achieve p is combined with sufficient amounts of fresh and recirculated alkaline material and incubated for a period of time, sufficient for distribution throughout the fibrous mass of the desired amount of alkaline material. During this treatment, the consistency brownstock pulp reduce and keep to a level of less than about 10 weight. preferably less than about 0.5 weight. Typically, the consistency of the fibrous mass more than 0,5 per cent because of lower consistency is economically disadvantageous for the process in this mode. The most preferred consistency is in the range from 0.5 to 4.5 weight.

You can choose the appropriate number (i.e. concentration and expenditure flows of materials) of the alkaline solution and the duration of the processing of the pulp at this stage to ensure distribution throughout the mass of pulp desired amount of alkaline material. Thus, in particular, an aqueous solution of hydrate of sodium oxide is combined with nizkochastotnoi fibrous mass in an amount which shall be sufficient to achieve a concentration of approximately 0.8 to 7 weight. hydrate of sodium oxide in the fibrous mass in terms of absolutely dry pulp after the stage of increasing the consistency of a Particularly useful source of hydrate of sodium oxide to this end the La, used to introduce or match nizkochastotnoi fibrous mass, and "a number", which is actually administered or held this fibrous mass. To hold the fibrous mass after the stage of improving the consistency desired amount of alkaline material with nizkochastotnoi fibrous mass in the mixer it is necessary to combine more quantity of alkaline material. For example, the quantity of alkaline material that is used (i.e. present) in the mixer, always exceeds the number actually entered (i.e. held in this mass and this mass) in the fiber after raising grease fibrous mass. In addition, the mixer load the entire alkaline material to ensure uniform dispersion of the alkaline material throughout nizkochastotnoi fibrous mass, the amount of which, after the stage of improving the consistency reaches introduced into the fibrous mass quantities desired for vysokokonkurentnoj oxygen delignification this fibrous mass. The preferred amount of the alkaline material, which actually held vysokokonkurentnoj fibrous mA and from about 1 to 3.8% for hardwoods.

Stage nizkokogerentnogo offset includes a uniform combination of unbleached pulp with an aqueous alkaline solution for a period of time of at least about 1 minute, preferably no more than about 15 minutes Phase shift complete, when the aqueous alkaline solution is almost evenly distributed throughout nizkochastotnoi fibrous mass. The duration of such treatment, a minimum of approximately 1 minute is usually sufficient to achieve almost uniform distribution, since this result is generally achieved after about 10 to 15 min of mixing. Although the operation of mixing for longer periods of time does not exert undesirable influence on the progress of the process, such longer periods of mixing does not give any additional enhancing effect with respect to the distribution of alkaline materials throughout the fibrous mass and leads to the need to increase the capacity of the mixing equipment to increase the length of stay therein. Setting this larger equipment increases the capital tetracytamine can be performed in a wide range of temperature conditions. Acceptable temperature range is within from about room temperature to 150oF (66oC), and the preferred temperature range is from about 90 to 150oF (32-66oC). The operation was performed under normal pressure and at elevated.

Depending on the specific process parameters of the delignification reaction the aqueous alkaline solution, which is used at the stage of mixing according to the present invention can be varied in a wide range, the variation amount of the aqueous alkaline material is covered by the scope of the present invention. Any expert in the art it is obvious that the amount of the alkaline solution, which is effective to achieve the objectives of the present invention depends primarily on the desired degree of delignification in the implementation of subsequent stages of oxygen bleach and fortresses that specific solution.

Preferred aqueous alkaline solutions of the present invention must be a solution of hydrate of sodium oxide concentration of approximately from 20 to 120 g/L. These solutions are mixed with low the,5 and 13.5 g/l, preferably amounted to about 9 g/L. for example, as a result of processing within 5 to 15 min of pulp consistency of 3 to 5% at a temperature in the range from 120 to 150oF (49-66oC) in the above concentrations of alkaline material to provide an even distribution of such alkaline material throughout the fibrous mass. In accordance with a preferred variant embodiment of the present invention an aqueous solution of hydrate of sodium oxide should be added to nizkobonitetnyh fibrous mass in a quantity which is sufficient to create a concentration of hydrate of sodium oxide in the range from about 15 to 30 weight. fibrous mass.

Treated with an alkaline material fibrous mass is sent to spustitelny installation, in which the consistency of the fibrous mass increase, for example, by pressing at least approximately 18 weight. preferably up to about 25-35 weight. According to the above method, the consistency should be increased to 29% More vysokokompetentnoe fibrous mass is fed into the reactor for oxygen delignification 20.

At the stage of improving the consistency of the pulp is also UD is asset return in the process. In the case where the consistency of the pulp fed to the mixer is of the same order (that is, approximately equal to or slightly larger) as the consistency vysokokonkurentnoj fibrous mass that comes out of the thickener, the amount of alkaline material used at the stage of combining, is minimal because all pressat successfully return directly to the mixer, where it is held on the stage alkaline processing nizkochastotnoi fibrous mass. In a mixer add the additional amount of alkaline material required to compensate for the amount that you spend for processing fibrous mass.

For pressata may be provided in the receiving tank. The presence of this receiving tank promotes a smooth, continuous flow process, since the possibility of the accumulation in it of large quantities of pressata ensures uninterrupted flow of pressata containing alkaline material in the mixer regardless of intermittent or continuous receipt of this pressata of the thickener. Thus, the receiving tank is a tank for alkaline material, which is. For example, the capacity of the tank should be approximately 6000 cubic feet (170 cubic meters). This volume is sufficient to manipulate pressata obtained during surgery alkaline processing unit with a capacity of 1000 t mass air drying in the day (MBC/day).

As stated above, the unbleached pulp is washed in the washing machine. Although washing of unbleached pulp, you can use the normal wash setting, using the appropriate source of service water, for this purpose it is advantageous to direct the wash water, which is returned to the process with the other stages. So, for example, use the wash installation with splitting the shower, which serves wash water from individual sources due course.

One part of the filtrate from the wash installation oxygen stages can benefit by its return to the process flow in the wash setting that allows you to reduce the water consumption for the entire process. Preferably this portion of the filtrate to submit to the first shower, mounted in the wash installation. The second shower directs a portion of pressata on the fibrous mass. These portions are used for p is part of the alkaline material in portions of pressata associated with the fibrous material and into the mixer. The wash liquid is directed to heat recovery system to save water in the mixer balance.

Pressat sent to the mixer, it is preferable to use the second shower washing installation, and on stage nizkochastotnoi alkaline processing. This prevents possible loss of alkaline material in the recuperation system, which can occur in the case of the introduction of pressata in leaching install due to "leakage" in the stream withdrawn from the wash installation.

In the case where the consistency of unbleached pulp flowing into the wash installation, of the same order as the thickener, the process can be carried out without any diversion of pressata of the thickener. This creates a vicious cycle in which all pressat returned directly to the mixer. The amount of alkaline material that is "lost" due to the retention of the fibrous mass increased consistency, easy to fill additional quantity of alkaline material added to the mixer or receiving tank. Thus, the quantity of alkaline material may be reduced to a minimum, since there are no losses xeloda consistency brownstock pulp, coming in leaching plant, below the consistency of the fibrous mass in the thickener in the mixer due to the return of pressata gradual accumulation of fluid. To exit this situation, part of pressata should be directed to the heat recovery system installation with the aim of preserving the faucet water balance. Usually directly into the mixer return a significant portion of pressata greater than 50% preferably about 75-95% and the remaining preset line served in the recuperation system installation. The rest of preset can be directed along the line splitting in the shower washing installation.

The flow of pressata can be divided so that part was continuously fed to the mixer, and the part is continuously directed to the washing machine through splitting the shower. However, the percentage of pressata again could be at least 50%, preferably in the range from about 75 to 95% of the total number of pressata in the stream, and the rest falls on pressata in the stream. The washing filtrate from the washing apparatus further directed to heat recovery system installed to save water in the mixer balance. In addition, in the recuperation system is that containing alkaline material fibrous mass is directed into the reactor an oxygen delignification, in which it in accordance with any of a number of well-known methods is introduced into contact with gaseous oxygen. According to the present invention suitable conditions for oxygen delignification include the introduction of gaseous oxygen at a pressure of approximately 80 to 100 pounds per square inch, 5,6-7,0 kg/sq. cm and vysokokonkurentnoj fibrous mass while maintaining the temperature of the fibrous mass in the range of about 90 to 130oC. the Average duration of contact between vysokokonkurentnoj fibrous mass and gaseous oxygen is in the range from about 15 to 60 minutes

After oxygen delignification reactor delignification fibrous mass is directed to the washing apparatus, in which the fiber is washed with water to remove all dissolved organic substances and produce high-quality, slightly coloured pulp. Hence, this pulp can be used for subsequent stages of bleaching with getting fully bleached product.

Additional advantages of the present invention can be identified during subsequent bleaching delignification lei, including ozone, hydrogen peroxide, chlorine, chlorine dioxide, hypochlorite, and the like. During the conventional bleaching processes using chlorine/chlorine dioxide to improve the degree of whiteness of the pulp treated with an alkaline material according to the above, use significantly reduced the total number of active chlorine in comparison with those used in the bleaching of fibrous masses that were previously subjected to oxygen delignification in accordance with known technologies. Thus, the total number of chlorine-containing chemicals, which are used in accordance with the present invention, less than about 15-35 weight. in comparison with the amount needed for the same source fibrous mass, which has not been treated with an alkaline material at a low consistency of this fibrous mass. Similarly in the case when the processing of fibrous masses should stage the alkali treatment, at this stage require a greatly reduced quantity of alkaline material in comparison with what is spent on the stage of bleaching fibrous masses, who were not evenly combined with the alkaline material at low consistency is positive for 25-40% of the weight. for the pulp treated with alkaline material at low consistency according to the foregoing.

In addition to economic benefits in relation to reduced amounts of chemical required for such processing, the implementation of the method of the present invention can also reduce the amount of environmental pollutants in the case of the use of chlorine, because such a process requires reduced amounts of chlorine. Moreover, due to the reduced number of chemicals used in this part of the system and decreases the number of pollutants of wastewater discharged from the plant to be processed, respectively, reduces the cost of equipment for wastewater treatment and network related savings.

The invention is illustrated by the following examples.

As used in this detailed description, the term delignification selectivity is used to denote the degree of degradation of cellulose in comparison with the relative proportion of lignin remaining in the fibrous mass, and is an indicator of the abilities in implementing such a way to get a solid fibrous mass with low lignin content. Differences Augite, for example, when comparing the ratio between the viscosity of the pulp with a number To or permanganate number. For the embodiment of the present invention, the lignin content in the fibrous mass can be determined either by number or by permanganate number. The difference between these values is quite obvious to any person skilled in the field of technology, so it can optionally translate one parameter to another. In all cases, unless otherwise specified, the number is 40 ml.

The viscosity of the bleached fibrous mass indicates the degree of polymerization of cellulose in bleached fibrous mass, and also characterizes itself fibrous mass. On the other hand, the number K is a measure of the amount of lignin remaining in the fibrous mass. Thus, in the reaction of oxygen delignification, which is characterized by high selectivity, get bleached fibrous mass of high strength (i.e. high viscosity) and low lignin content (i.e. low K).

Example 1. (Alkaline processing vysokokonkurentnoj fibrous mass according to known techniques). Unbleached Kraft pulp and the pulp from the wood the full solution to the consistency of approximately 30-36 wt. having vysokokonkurentnyj Mat brown stock. This Mat unbleached pulp was subjected to further spraying a 10% solution of hydrate of sodium oxide in an amount sufficient to achieve concentrations of hydrate of sodium oxide of about 2.5 weight. in terms of dry weight of the fibrous mass. Next to bring consistency Mat brown stock to approximately 27% in a sufficient amount of added water. Then vysokokonkurentnyj Mat unbleached pulp was subjected to oxygen delignification subject to the following conditions: 110oC, 30 min, oxygen pressure of 80 pounds per square inch, 5.6 kg/sq. see After oxygen delignification of pulp carried out in accordance with this procedure, this mass was subjected to the tests in which it was discovered that her number was 13 (permanganate number 15,2) and viscosity in the complex of Ethylenediamine and copper (EDM) was approximately equal to 14.8 SDR. This subjected to oxygen delignification of fibrous mass is then sent to the bleaching by known techniques. Strength and physical properties as subjected to oxygen delignification of pulp and fully bleached fibrous masses are given respectively in table. 1 and 2.

Examples 2-5. (Nizkochastotnaya alkaline processing fibrous mass). Examples 2-5 illustrate the increase of the degree of delignification and delignification selectivity, which was achieved in the process vysokokonkurentnoj oxygen delignification of fibrous masses subjected to processing with an alkaline material only at low consistency.

Example 2. In the mixer introduced the same kind of unbleached pine Kraft pulp, as that was used in experiment example 1. To bring consistency brownstock pulp in the mixer until about 3 weight. added just the right amount of dilution water. To achieve a 30% concentration of hydrate of sodium oxide in terms of AU the weight of the fibrous mass is added sufficient 10% solution of hydrate of sodium oxide. Unbleached weight and an aqueous solution of Hydra the Oia alkaline material with unbleached weight. Then the mixture of unbleached pulp with an alkaline material subjected to extrusion to the consistency of approximately 27 weight. After pressing, the content of the hydrate of sodium oxide in the fiber was equal to approximately 2.5% as in experiment example 1. Next treated with an alkaline material unbleached mass was subjected to bleaching in accordance with the procedure oxygen delignification, which is described in example 1. Delignification oxygen fibrous mass is then washed to remove organic substances. The number To the obtained oxygen stage fibrous mass was equal to 9 (permanganate number was 10.8) and the viscosity in the EDM - 14,0. Bleached with oxygen fibrous mass was subjected to additional bleaching by known techniques in compliance with the conditions described in example 1. Properties delignification oxygen fibrous mass and fully bleached fibrous mass obtained in the experiment of this example, also shown respectively in the above table. 1 and 2.

From the comparison of examples 1 and 2 it can be noted that in the procedure of example 2, get delignification oxygen fibrous mass with a higher degree of delignification the CSO method of example 1, when the alkaline material is used for processing vysokokonkurentnoj fibrous mass. Furthermore, the use of nizkochastotnoi alkaline treatment of the pulp as described in example 2, allows to achieve a high degree of delignification without significant changes in mechanical properties. This results in increased selectivity of delignification.

Due to the reduced numbers To fibrous masses, resulting in experiment example 2, the implementation of subsequent stages of bleaching can be adjusted in such a way as to obtain a fibrous mass with a higher degree of delignification. Therefore, the implementation stages of such bleaching of pulp requires less bleaching agents (which can be seen from the data table. 4) or the time of bleaching than in the case of the fibrous mass, which was not subjected nizkochastotnoi treatment with an alkaline material.

Example 3. The fibrous mass of the softwood (pine), obtained by the method similar to the above example 2, compare with the one that was obtained in the usual way (i.e. without phase nizkochastotnoi alkaline processing) as in uh is but to process only vysokokonkurentnoj fibrous mass, sent on subsequent oxygen delignification was 45 pounds/ton of absolutely dry mass (lb/ton) of 20.4 kg/t or 2.3% of this consumption of alkali average reduce the number To around the reactor for oxygen delignification was 10% At the same flow rate of hydrate of sodium oxide, used for processing only nizkochastotnoi fibrous mass before vysokokonkurentnoj oxygen delignification average reduction in the delignification was equal to 13 units: 30% increase to what is achieved by conventional technology.

The average number K and the viscosity of conventional fibrous masses were equal, respectively, 12,1 14,4 SDR. For the method nizkochastotnoi treatment with an alkaline material, the average number of K at the same viscosity (14,0 SDR) was equal to 8.8, which means increasing the selectivity of delignification by approximately 41% (1,69 against 1,19) as shown in the table. 5.

The characteristics of the individual Department to fibrous masses, obtained in accordance with the above method nizkochastotnoi alkaline treatment, compared with the characteristic fibrous masses obtained in the usual way.

The results are presented in Nina subsequent stages of bleaching was reduced by approximately 1/3 (i.e. 69.4 lb/ton against 46.6 lb/ton). In addition, the flow rate of the hydrate of sodium oxide for the implementation stage of the alkali treatment also reduced by about 1/3 (24 lb/t, compared to 35 pounds/ton). The consumption of chlorine dioxide in the final stages of bleaching was reduced by approximately 1/6 (9 lb/t against 10.6 lbs/tons)

Example 4. Comparative tests similar to the above, in example 3 was conducted using the pulp from hardwoods. Again it was found that the application of the processing method, when the alkaline material is injected only in nizkobonitetnyh fibrous mass in contrast to a conventional processing method, in the course of the reaction of oxygen delignification achieved significantly greater reduction in the number K. the Flow rate of the hydrate of sodium oxide in oxygen delignification of hardwoods is 27 lb/t, and 12.2 kg/t or 1.4% In the implementation of known technology reducing the number of the on the stage of delignification was approximately 5% At the same flow rate of hydrate of sodium oxide in the implementation of the method described above nizkochastotnoi processing the average decrease in the number amounted To approximately 7,3% that is, the increase was equal to almost 50%

The average number K and the viscosity of the mass of others who have achieved the number To, equal to 6, and the viscosity of 17.7. In addition, the number K at the same viscosity as in the case of normal processing of the pulp with an alkaline material (16 SDR), was equal to 5.8. When this is achieved approximately 40% increase in the selectivity of delignification (2,95 against 10), as it is obvious from the data table. 6.

The selectivity of delignification can also be expressed in changes of viscosity against data change To the brown stock and delignification fibrous masses. When compared to fibrous masses, who were treated with an alkaline material only at a low consistency, processed by the conventional methods there is a greater increase in the selectivity of delignification in a higher degree the delignification. To change the number To 4% average change in viscosity was 4 SDR for fibrous masses obtained by the conventional methods. In contrast, change the number To the same viscosity changes in fibrous masses, obtained by the method nizkochastotnoi processing fibrous mass was 7% If to Express this result in data degree of selectivity, the selectivity for processed nizkochastotnoi able fibrous mass was equal to 1,BR> Comparison of characteristics subjected to oxygen delignification in a separate Department fibrous masses, obtained by the above nizkochastotnoi treatment with an alkaline material, consumption of bleaching chemicals with similar characteristics to the fibrous mass, the obtained oxygen delignification by the conventional methods, are given in table. 6.

The data table. 6 show that the total consumption of active chlorine in the chlorine stage was reduced by approximately 1/6 (i.e. 34.9 lb/ton against 41.6 lb/ton), while the need for alkali on stage alkaline processing has been reduced by more than 29% (i.e., 13.3 lb/ton versus 18.9 lb/ton) compared with previously known techniques. The consumption of chlorine dioxide in the final stages of bleaching decreased by more than 14% (i.e., 4.7 lb/ton against 5.5 lb/tons) In regard to viscosity and the degree of contamination of the final fibrous mass, they were almost identical.

Example 5. To illustrate the effect nizkochastotnoi processing of alkaline material on the fiber prednisoloni delignification and promote the overall effectiveness of reducing the permanganate number of the total output of the product the op is agentname numbers unbleached Kraft and as-masses.

The results obtained are given in table.7.

For the case of regular unbleached Kraft pulp with permanganate number 28,1 treated with hydrate of sodium oxide (2.4% of the weight of pulp after pressing) at 3% consistency for 5 min initial permanganate number decreased by 1.6 units constituting the fibrous mass after treatment of 26.5. This indicates 9.6% of the common reducing permanganate number, which was achieved after the alkali treatment and oxygen delignification (permanganate number -12,0). The yield on the entire stage nizkochastotnoi alkaline treatment was equal to 99.5% of the Approximately half of the losses (0.5% ) product yield may be due to loss of lignin, while the rest is accounted for hydrocarbons. The total yield of product after oxygen delignification has accounted for 95.2%

The same source unbleached mass was subjected to processing by the hydrate of sodium oxide (2.1% of the weight of pulp after pressing) at 3% consistency for 15 minutes Initial permanganate number decreased by 0.6% reaching 27,5. This indicates the assistance of a General reduction of permanganate number after nizkochastotnoi alkaline treatment and kislorodny 98,7%

For the case of unbleached Kraft/AO-mass low permanganate number, treated with hydrate of sodium oxide (2,11% by weight of pulp after pressing) at 3% consistency for 5 min permanganate number decreased by 1.3, reaching 20,3. This reduction of the permanganate number indicates 10% common drop permanganate number after oxygen delignification (permanganate number 8,9). This was not observed in almost any loss of yield on all stages of the alkali treatment. The total yield of product after oxygen delignification was equal to 96.7% In the second oxygen delignification the same source of unbleached Kraft/AC-masses were achieved the same permanganate number of 8.1 and yield of 97.2 per cent

This example 5 shows that during nizkochastotnoi alkaline processing fibrous mass is not an appreciable level of delignification. This example also shows that no matter the duration of treatment with an alkaline material at a low consistency within approximately 15 minutes, However, examples 2-5 additionally show that nizkochastotnaya alkali treatment leads to a significant Lortnoc delignification, in comparison to what is achieved in the processing of fibrous masses in the usual way. This example shows also that the proposed method is effective in the case of unbleached pulp with low permanganate number, when it is desirable to achieve very low permanganate number without any substantial increase in viscosity.

Uniform distribution of alkaline material throughout the fibrous mass on stage nizkokogerentnogo combination provides a more optimal connection of the fibers of the fibrous mass with the alkaline material than is possible under any known technology. This leads to improved selectivity of delignification during subsequent oxygen delignification, namely, that delignification unbleached weight gain strength and a degree of delignification, which usually exceeds achieved according to known techniques. In addition, at this unexpected perfection reaches the selectivity of delignification in the reaction of oxygen delignification.

In the case where the alkaline material is injected only in vysokokompetentnoe fibrous mass, as is the case in conventional techniques, without things is achieving only 50% delignification, that is, the reduction of the permanganate number of the fibrous mass. A practical embodiment of the present invention makes it possible to achieve reduction to the original pulp weight more than 50% and usually at least about 60% during oxygen delignification almost without any damage to the pulp part of the fibrous mass. At desire it is possible to achieve this reduction by 70% or more.

For example, when applying for a stage oxygen delignification depending on the specific type of wood and the method of pulping, which is subjected to a specific type of wood, the number of K for a given fibrous masses are in the range from about 10 to 26. After delignification, the number reduced To about 5-10. For fibrous mass of the softwood number is usually in the range of 20-24 (target is 21) before delignification, whereas after delignification numbers are in the range of 8-10. For fibrous pulp from hardwoods to delignification number is 10-14 (target) is 12.5), and after delignification numbers, usually achieved by implementation of the proposed method, are 5-7.

Fiber is after delignification it exceeds approximately 13 (usually 14 or more for softwoods and 15 or more for hardwoods). Usually such a change in viscosity from that to delignification, insofar as after delignification could be about 6 centipoise or less. Moreover, it was found that to reduce the number To approximately up to 17% change viscosity to change the number To turns out to be permanent.

Thus, the implementation stage nizkokogerentnogo combining with the alkaline material can improve the selectivity of delignification with increase in the delignification of at least 20% in comparison with that achieved in the implementation of known methods of delignification. Preventing damage to the cellulose component of the fibrous mass is evident from the minimal changes of viscosity of the pulp from the one that was to delignification, to the one that was after delignification with oxygen.

Example 6. The data obtained and shown in examples 2-5, together with numerous other data that were predicted and obtained, in graphical form found the owl reflected in the drawing for the pulp from softwood. The drawing shows also the graphs that result from the combination of data for the actual testing, as well as mnogoe softwoods in the implementation of the previously known method of processing fibrous mass, described in example 1.

As shown in the drawing, the implementation of the previously known method of example 1 allows after oxygen delignification to achieve typical properties of the fibrous mass, as determined by the schedule indicated in the figure labeled "conventional technology". It is desirable to maintain the strength of the fibrous mass, as determined by viscosity at higher levels of viscosity, while providing effective delignification, as it is determined to reduce the number To. the Drawing shows that when data values of the viscosity in accordance with the schedule that corresponds to the present invention, improved delignification (reduced number) can be achieved by treatment with an alkaline material nizkochastotnoi fibrous mass, whereas according to the schedule for conventional technologies are achieved lower delignification and value of viscosity.

Example 7. To further illustrate the possibility of achieving uniform distribution of the alkaline material in the fibrous mass in accordance with the method of the present invention were conducted the following laboratory tests. Prepared unbleached pine fibrous mass with the number To 19 and a temperature of 60oC for respectively 1 and 15 minutes After that, the consistency of the pulp was increased to 27% and it was found that the content of the hydroxide of sodium in it was approximately equal to 0.67% of This fibrous mass was sent to the reactor for oxygen delignification at a pressure of 80 pounds per square inch, 5.6 kg/sq cm, which was passed at a temperature of 110oC for 30 min without further addition of alkaline material.

After that, another two samples of unbleached fibrous pulp, the consistency of each of which accounted for 3% of treated introduction it is estimated that approximately 35% of hydrate of sodium oxide and aged at a temperature of 60oC for respectively 1 and 15 minutes Later the consistency of the pulp was increased to 27% while keeping the content of the hydrate of sodium oxide in the fibrous mass to 3% and then this fibrous mass was sent for oxygen delignification at a pressure of 80 pounds per square inch, of 5.6 kV/sq. cm. and at a temperature of 110oC for 30 min without adding additional quantities of alkaline material. The results obtained are summarized in the following table. 8.

Samples E-H treated fibrous mass retain significantly more (then) large quantity of hydrate of sodium oxide. Reducing the number To samples E-H fibrous mass was equal to at least approximately 55.3 per cent while reducing the number K in the samples a-D were significantly lower, amounting in the best case, 11.3%, So, anyway, in the samples (E-H), processed in accordance with the present invention, increased by approximately 49.6% more than in the comparative samples.

Using the same unbleached fibrous mass this example, the above test was repeated with making the following changes (see tab. 8A).

For each case changes the processing time of the hydrate of sodium oxide was 2 and 15 minutes As indicated above, the consistency of unbleached fibrous mass was almost the same (3,5% against 3%).

The results obtained are given in table. 9.

With the introduction in nizkobonitetnyh fibrous mass increased quantities of hydrate of sodium oxide in vysokokonkurentnoj fibrous mass held in a much higher quantity of hydrate of sodium oxide. Due to this increased the number of hydroxide sodium reduction To result in samples P-M is at least approx is), prepared in accordance with the proposed method achieves a higher degree of delignification in comparison with associated with them samples of at least 41,9% As stated above, this is due to increased amounts of hydrate of sodium oxide, held vysokokonkurentnoj fibrous mass with uniform mixing and distribution of the appropriate quantity of hydrate of sodium oxide in the entire nizkochastotnoi fibrous mass.

1. The way oxygen delignification of unbleached pulp, which includes the introduction in the unbleached pulp weight of alkaline material to reduce the consistency of the pulp below 10 wt. and education nizkochastotnoi mass, increase the consistency of the pulp to at least 18 wt. removing the liquid phase and the oxygen treatment vysokokonkurentnoj pulp, characterized in that before you raise the consistency of the mass nizkobonitetnyh mass combine with alkaline material sufficient for its uniform distribution throughout the fibrous mass, and oxygen treatment machine vysokokompetentnoe weight with the alkaline material is at least 0.8 7 wt. counting on absolutely vysokokonkurentnoj fibrous mass, and more than 50% of the removed liquid phase returns directly to the step of combining with the alkaline material.

2. The method according to p. 1, characterized in that remote part of the liquid phase return for washing of unbleached pulp before wednes it alkaline material.

3. The method according to p. 1, wherein the unbleached pulp mass is used with consistency, equal to or greater than the consistency vysokokonkurentnoj pulp and almost all remote liquid phase returns to the step of combining with the alkaline material.

4. The method according to p. 1, characterized in that it additionally produce the accumulation of a specified number of remote liquid phase for continuous return it directly to the step of combining with the alkaline material.

5. The method according to p. 1, characterized in that it further rinse treated with oxygen pulp with the formation of the flow of flushing water and return part of the flow of wash water to the washing of unbleached pulp before the introduction into it of the alkaline material.

6. The method according to p. 1, characterized in that when combining the alkaline material with nizkochastotnoi pulp mass, the latter is used with consistency, equal to 3 to 5 wt.

7. The method according to p. 1, characterized in that PE, characterized in that to improve delignification selectivity reduce the Kappa number, vysokokonkurentnoj pulp more than 50 without significant damage to the components of this mixture.

9. The method according to p. 1, characterized in that to improve delignification selectivity reduce the number vysokokonkurentnoj pulp from 10 to 26 to delignification and from 5 to 10 after delignification.

10. The method according to p. 1, wherein the unbleached pulp mass use of softwoods, and the quantity of alkaline material introduced into the mass is 1.5 to 4 wt.

11. The method according to p. 2, wherein the unbleached pulp mass use of hardwoods, and the quantity of alkaline material introduced into the mass is 1 to 3.8 wt.

 

Same patents:

The invention relates to pulp and paper production and can be used for thickening (dewatering, concentration) of the fibrous pulp

The invention relates to the pulp and paper industry

The invention relates to the pulp and paper industry, in particular to a method of bleaching cellulosic staple fiber without the use of chlorine with ozone according to the three-step method consisting of bleaching with oxygen in the presence of hydrogen peroxide (EOR-step), bleaching with ozone (Z-stage) and peroxide bleaching (P-step)

The invention relates to the field of pulp and paper production and is intended for use in the production of bleached pulp

The invention relates to the production of bleached fibrous semi-finished and can be used to obtain bleached Kraft pulp for various purposes in the cooking apparatus of periodic action

FIELD: pulp and paper industry.

SUBSTANCE: disclosed is bleached craft fiber from conifer species wood cellulose with high content of alpha-cellulose and higher brightness and whiteness.

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19 cl, 12 tbl, 7 ex

FIELD: production of cellulose fibers; obtaining the product in form of dried separated fibers of cellulose.

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9 cl, 12 dwg, 3 tbl, 3 ex

FIELD: pulp-and-paper and chemical industry.

SUBSTANCE: method involves preparing mixture of wet fibrous pulp and gaseous transportation agent; feeding resultant mixture into tubular reactor; feeding mean concentration fibrous semi-finished product into elevated tank and mechanically fluidizing for imparting fluidity upstream of pump impeller; feeding into pressing chamber for condensing to high concentration by squeezing and removing liquid; dispersing into fibers; providing fluidizing by mixing with transportation agent; pumping out to further processing station. Apparatus has elevated tank for receiving of fibrous semi-finished product, built-in screw with feeding coils; mechanical liquefier, pump impeller for pumping out of liquefied pulp into pressing chamber equipped with barometric tube for discharge of squeezed liquid and vacuum tube for removal of non-condensed gases. Dehydrating part of screw is mounted within pressing chamber. Apparatus is further provided with pulp mass plug, disperser, mixing chamber, and transportation pipeline. All functional mechanisms are mounted on single shaft which is fixed on pin of drive electric engine.

EFFECT: increased efficiency of process.

5 cl, 2 dwg

FIELD: paper industry.

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38 cl, 5 dwg

FIELD: textiles, paper.

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12 cl, 6 dwg, 4 tbl

Paper making method // 2384661

FIELD: textile, paper.

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17 cl, 2 tbl, 3 ex

FIELD: textiles, paper.

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EFFECT: device improves the performance of pulp processing due to reducing of fiber content in the filtrate, and reducing the risk of clogging of a suspension of pulp.

12 cl, 5 dwg

FIELD: textiles, paper.

SUBSTANCE: device comprises a pressing roller, which is located with the ability to rotate during operation and which has a perforated outer surface for dewatering of cellulose pulp. The fixed guiding surface is located at a distance from the perforated outer surface of the pressing roller and forms essentially a closed tank. Passage for the pulp is formed between the perforated outer surface of the pressing roller and the fixed guiding surface, so that during the work the pulp is moved in the direction of rotation and at the end of the passage for the pulp it is pressed in the place of squeezing. At that the radial distance between the fixed guiding surface and a corresponding pressing roller is generally increasing in the direction of the place of squeezing, so that the tank moves apart in the direction of the place of squeezing. Also near to the place of squeezing the fixed guiding surface has no holes for leaking out fluid, so that the pressure that is created at the place of squeezing is not lost.

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9 cl, 5 dwg

FIELD: textiles, paper.

SUBSTANCE: invention relates to a device for washing and dehydration of the pulp stock, which comprises the first and second rotatable squeezing rollers (102, 104) having a permeable outer surface (106, 108), and a housing which comprises a bath (114, 116, 118) in which the squeezing rollers (102, 104) are mounted, where between the squeezing rollers (102, 104) the contact area (112) of the press is defined in which the pulp stock is squeezed. The bath (114, 116, 118) comprises a first side element (114) of the bath and a second side segment (116) of the bath. The device comprises a first pulp stock distribution device (126) for distribution of the pulp stock over the first squeezing roller (102), and a second pulp stock distribution device (128) for distribution of the pulp stock over the second squeezing roller (104), where at least the first pulp stock distribution device (126) is mounted on the first side element (115) of the housing thereby the first pulp stock distribution device (126) can be taken from the first squeezing roller (102) with the first side element (115) of the housing when it is moved from its closed position to its open position.

EFFECT: invention enables to access to different parts of the device and to carry out maintenance work.

13 cl, 2 dwg

FIELD: textiles, paper.

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EFFECT: improvement of the device.

10 cl, 3 dwg

FIELD: machine building.

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EFFECT: structure of a press is compact and simple and provides easy access to mass that may stuck between a drum and a guide plate so that the press can be quickly cleaned at possible shutdowns.

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