Method for production of solutions for sulfite pulping of wood

FIELD: woodworking industry.

SUBSTANCE: water medium, which comprises cooking base, is treated with gas mixture that contains sulfur dioxide. For this purpose device is used with tangential supply of water medium, which is equipped with porous element that separates it internal space into two longitudinal cavities. Gas mixture is supplied along one side of element and further to water medium through its pores under pressure of 0.6-1.2 MPa, and water medium is supplied along another side of element under pressure that is 0.04-0.06 MPa lower than pressure of gas mixture. Water medium is supplied in the form of main and additional flows. Water medium after its treatment with gas mixture is exposed to floatation cleaning with application of inertial gaseous part of processing products as flotator. Blower products from cooking boilers are supplied into water medium in process of its floatation cleaning.

EFFECT: increased efficiency of process and simplified process.

4 cl, 1 dwg, 3 ex

 

The invention relates to the technology of preparation of solutions for the cooking of wood in sulfite method using different types of cooking base or mixtures cooking bases and can be used in the pulp and paper industry.

Known method of preparing solutions of sulfur dioxide and bisulfite magnesium, ammonium and sodium, as well as monosulfite sodium implemented in bubble absorption column equipped with sieve plates. The method includes preparing an aqueous solution or suspension of the cooking grounds, the filing of a solution or suspension from the top of the device, the infeed into the apparatus of a gas mixture containing sulfur dioxide, the output of the apparatus with an aqueous phase products of interaction of the base and sulfur dioxide, as well as exhaust gas containing sulfur dioxide. In this way you can get a 120 m3/h raw cooking solution by weight in bubble columns 7000 kg ("Technology of pulp and paper production. Reference materials". Volume I (Part 1). Str-316, St. Petersburg, publishing house of St. Petersburg state forest technical Academy (SPbSTU), 2002).

The closest in technical essence and purpose is a method, implemented in the tower pressure is supplied by a nozzle. In this way the total pressure of the gas mixture fed to the tower SN is zu, 0.15 MPa. Aqueous medium containing a base, comes top of the tower. The performance of the system by this method 2200 m3/day (to 91.6 m3/h) raw cooking solution. The mass of metal structures 10.8 tons, the weight of the lining 30 tons, the weight of the nozzle 30 so ("Technology of pulp and paper production. Reference materials. Volume I (Part 1). P. 320, St. Petersburg, publishing house of St. Petersburg state forest technical Academy (SPbSTU), 2002).

The drawback of both these methods is their low performance per unit mass of plants, as well as the instability of the ratio of concentrations of the components of the solution during its preparation.

The positive results of the use of the present invention are to increase productivity per unit of mass used setup, easy to adjust characteristics of the cooking solutions in the process of preparing the composition and concentration of components, as well as the possibility of using the inert part of the gas mixture in high-performance flotation clean cooking solutions without the cost of compression of floating gas. This part in the performance on the cooking acid 120 m3/h is more than 8000 nm3/h of nitrogen mixed with about 3-6% oxygen.

These positively the e results are achieved, however, a method for preparation of solutions for sulfite pulping of wood by treatment in a mass transfer apparatus of the aqueous medium containing the cooking base, a gas mixture containing sulphur dioxide at high pressure mixtures according to the invention using the apparatus with a tangential feed of the aquatic environment, equipped with a porous element that divides the internal space into two longitudinal cavity, the gas mixture is fed on one side of the element and then into the aquatic environment through its pores under the pressure of 0.6-1.2 MPa, and the water environment served on the other side of the element under pressure 0.04-0.06 MPa below the pressure of the gas mixture. The aquatic environment it is advisable to apply as primary and secondary flows. The aquatic environment after processing gas mixture is subjected to flotation treatment use as a floatation agent inert gaseous side products. In the aquatic environment during its flotation cleaning serves food waste flow from the digesters.

Method of preparation of raw cooking acid is carried out in a mass transfer apparatus consisting of a hollow body in the form of a tube with a bottom and a lid, equipped with a tangential feed of the water environment and a porous element located inside the tube and dividing the internal space into two longitudinal cavity, communicating is between an exclusively through the pores of the element, means feeding the aqueous phase in the form of two streams and the gas mixture respectively in the outer and the inner cavity, means of output of products of processing of the aquatic environment of the gas mixture.

View cross-section of the device shown in the drawing, where 1 is the wall of the pipe body, 2 - porous element consisting of several sealed interconnected lateral sides of the sections, 3 - mounting sections of the sides to each other, 4 - external cavity to the water environment 5 - tool tangential feed of the water environment in the cavity 4, 6 - the means of supplying additional water flow protection, 7 - cavity for a gas mixture of 8 - tool feed gas mixture into the cavity 7.

The process is as follows. The main flow of aqueous medium containing the cooking base in solution or in suspension, is fed under pressure tangentially to use 5 in the external cavity 4. To enhance the rotational movement of the fluid flow, it is expedient in the cavity under pressure to submit tangentially at several points along the axis of the housing using the 6 additional quantity of the water environment. Upon receipt of the cooking solution with a mixture of salts of two types of bases, such as sodium and magnesium, additional thread can serve as a means of feeding in the aquatic environment specified number vtoro what about the Foundation. Upon receipt of a solution of magnesium salts of sulphurous acid additional thread can be the solution of sulfite or acid magnesium bisulphite solution of sulphurous acid. With the additional flow in the water system can also be submitted coagulants and flocculants required for effective flotation clean cooking solutions.

The inner cavity 7 serves under a pressure of 0.6-1.2 MPa gas mixture containing, for example, from 15 to 18% of sulfur dioxide, 79% nitrogen and 3-6% oxygen. The pressure of the gas environment in the inner cavity 0.02-0.06 MPa higher than the pressure of the water environment in the external cavity of the apparatus. This pressure differential provides the filtering process gases from the internal cavity through the pores of the partitions in the external cavity, i.e. in the flow of the water environment. The gases flow from the porous elements in the form of tiny bubbles, which are washed away by the fluid flow and dissolve in it. In the presence of water environment Foundation with a given concentration is a reaction between sulfur dioxide and the substrate with the formation of salts of sulfurous acid of a given composition. The solubility of gases in water system at elevated pressures (0.6 to 1.2 MPa) is significantly higher than their solubility at normal pressure. Accordingly, when high concentrations of dissolved sulfur dioxide is sharply accelerated the whole process.

Using featur is imago method and device described above may fast and accurate control of the following process parameters without stopping: the pressure of the gas mixture and consequently the rate of supply of sulfur dioxide through the pores partitions into the liquid phase and the formation of a solution of salts of sulfurous acid, flow rate of liquid medium and the intensity of its rotation without changing the fluid pressure, and composition of the cooking bases in the aquatic environment inside the apparatus. With proper choice of these parameters have the solution with a given component content in a single pass, i.e. without recirculation of the water environment. Regulation of the process parameters is carried out at the pH of the liquid phase at the outlet of the device.

Upon receipt of salts of sulfurous acid in the proposed method, the salt solution is withdrawn from the apparatus at high pressure in the form of a gas-liquid system, which is sent under this pressure in the dispenser in the chamber of the flotation. The water pressure is reset to normal and the chamber volume gas-liquid mixture flows in the form of the aqueous phase, saturated fine bubbles of nitrogen, and small amounts of oxygen, which go up, capturing suspended in the liquid phase coagulopathies particles. These particles are separated from the salt solution with the foam layer.

In the flotation machine serves well as liquid and gaseous products of blow-offs taken from the digesters in the process of cooking wood. In the end you get a cooking solution with specified characteristics: the type or species of the cooking base and their end is Tracia, the content of bound and free sulfur dioxide.

The test method was performed using connected in series on the main stream of the liquid phase three mass-transfer apparatus of the type ADT, converted to allow separate tangential feed in an external cavity of each of the two streams of water environment, means submission to the apparatus through the bottom of the gas mixture. Apparatus is also provided means for measuring the pressure of the gas and liquid phases, means for sampling the liquid phase pH. The tests used a gas mixture of sulfuric furnace containing 15% of sulfur dioxide, 79% nitrogen and 6% oxygen. Solutions or suspensions of grounds with a predetermined concentration was prepared by known methods.

The following examples illustrate the proposed method.

Example 1. Prepare a solution of soda ash with its content in terms of sodium oxide of 1.94%. This solution in the apparatus serves the primary and secondary flows under pressure of 0.54 MPa. The gas mixture is fed into the machine under a pressure of 0.6 MPa. At the exit of the device get wet bisulfite solution containing only sulfur dioxide 3,4%associated 2,0% and having a pH value of 5.6. After mixing the boiling solution in the flotation cell with the specified amount of the liquid phase and the products of blow-offs taken from the digesters in p is acesse cooking, get cooking solution with the content of total sulphur dioxide 3,2%associated SO21.5% and a pH of 2.5.

Example 2. Preparing a suspension of magnesium hydroxide and feed it into the machine under pressure of 1.18 MPa primary and secondary flows. The gas mixture is fed under pressure of 1.2 MPa. At the outlet of the flotation cell after mixing gas-liquid products with the products of the waste flow from digesters receive bisulfite cooking solution with the content of total sulphur dioxide 5,19%related to 2.66%, the bases in terms of magnesium oxide of 1.66%, the pH of the solution to 4.5.

Example 3. Prepare bisulfite cooking solution on a mixed magnesium-sodium base at a ratio of magnesium oxide: sodium oxide = 9:1. The main flow of the suspension of magnesium hydroxide, sodium base in the form of soda ash is served in a mass transfer apparatus with the additional flow. The pressure of the water environment in the apparatus 0.84 MPa, the gas mixture of 0.9 MPa. At the outlet of the flotation cell after mixing with the products of blow-offs get cooking solution with content just SO25,5%, linked to 2.67%, pH 2.3.

To match the performance of the method and, accordingly, the installation and the way the prototype recalculated experimental data for examples on the performance of 100 m3/H. To ensure that this performance of the proposed method is sufficient and the user device with the cross-sectional area of the internal cavity, the equivalent section of the pipe with a diameter of 210-240 mm Maximum weight industrial unit in this case will not exceed 3000 kg At the same time provides the specified part of the cooking acid and its stability.

1. The method of obtaining solutions for sulfite pulping of wood by treatment in a mass transfer apparatus of the aqueous medium containing the cooking base, a gas mixture containing sulphur dioxide at high pressure mixture, characterized in that use the apparatus with tangential feed water environment, equipped with a porous element that divides the internal space into two longitudinal cavity, the gas mixture is fed on one side of the element and then into the aquatic environment through its pores under the pressure of 0.6-1.2 MPa, and the water environment served on the other side of the element under pressure 0.04-0.06 MPa below the pressure of the gas mixture.

2. The method according to claim 1, characterized in that the aquatic environment serves as the primary and secondary flows.

3. The method according to claim 1, characterized in that the aqueous medium after processing gas mixture is subjected to flotation treatment use as a floatation agent inert gaseous side products.

4. The method according to claims 1 and 3, characterized in that the aqueous environment during its flotation cleaning serves food waste flow from the digesters.



 

Same patents:

The invention relates to the pulp and paper industry and can be used in the production of bisulfite pulp

FIELD: pulp-and-paper industry.

SUBSTANCE: part of solution with pH 3.0-5.0 is brought into contact with sulfur dioxide until acidic (pH 1.5-3.5) bisulfite solution is obtained. Solution is then subjected to interaction with lump brucite fraction 10-150 mm until pH 3.0-5.0 and percentage of bound sulfur dioxide 47-55% are attained.

EFFECT: increased workability of process due to reduced equipment dimensions because only a small apparatus is required, which can be loaded with brucite at any time periodically or continuously.

1 tbl, 2 ex

FIELD: paper-and-pulp industry.

SUBSTANCE: method is intended for use in production of cellulose fabricated from fibrous intermediate products via treatment with magnesium-based bisulfite cooking liquor using regenerated chemicals. Method is accomplished as follows. Solution containing magnesium bisulfite and magnesium monosulfite is prepared in system of regeneration of chemicals and heat from exhausted lyes at 60-70°C. Resulting solution is then saturated with sulfur dioxide in the form of gas emissions and/or condensates formed during cooking cellulose and concentrating exhausted lyes to form magnesium bisulfite and sulfurous acid solution. Preparation of the solution is effected at pH 4.5-5.0 and bound sulfur dioxide content 51.0-55.0%, while saturation of resulting solution with sulfur dioxide is effected to pH 2.8-4.5 and bound sulfur dioxide content 47.0-51.0%.

EFFECT: increased feasibility of method due to simplified technology and reduced operational expenses.

1 tbl, 2 ex

FIELD: pulp-and-paper industry, in particular cellulose production.

SUBSTANCE: sulfur dioxide is brought into reaction with magnesia raw material (e.g. cake brucite ) with grade of 50-600 mm and initial pH 1.5-2.5. Process is carried out up to pH 2.8-3.5 and content bonded sulfur dioxide 47.0-49.5 % followed by separation of exhaust gas from solution. One-step process is carried out at 70-900C.

EFFECT: method of improved processibility due to decreased number of process steps.

1 tbl, 3 ex

The invention relates to the pulp and paper industry and can be used in the manufacture of pulp on a mixed basis of the hardwood intended for printing, writing paper, sanitary paper types and generatenode

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The invention relates to the pulp and paper industry and can be used in the production of semichemical pulp

The invention relates to a method for production of cellulose and can be used in the pulp and paper industry in the manufacture of sulphite pulp with a lower content of resins and fats

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The invention relates to the pulp and paper industry and can be used in the production of pulp from hardwood

FIELD: paper industry.

SUBSTANCE: device comprises hollow cylindrical body with tightly attached bottom and cover. Body contains at least two porous elements, which are equipped with facilities for fixation to body, cover plug, facilities of tangential supply of liquid phase inside body, facilities of gas supply inside body, facilities for withdrawal of products of gas dissolution in water medium. All porous elements are equipped with facilities of tight fixation of them to each other by lateral sides and by end sides to bottom of body and cover-plug, and altogether they create tight regular volumetrical body, which creates longitudinal external and internal cavities in its internal space together with body walls, being communicated to each other only through pores of elements for separate supply of water medium and gas accordingly. Axis of internal cavity matches axis of body.

EFFECT: simplified manufacturing of device elements, unification of porous elements, simplified assembly of device and its maintenance.

4 cl, 3 dwg

Method of pulping // 2368716

FIELD: textiles; paper.

SUBSTANCE: method refers to sulphate pulping and can be used in pulp and paper industry. The method comprises cooking hardwood chip in alkaline cooking liquor in the presence of organic additive. SAA of non-ionic type - OS-20 compound is used as additive. This is a mixture of polyoxyethylene glycolic esters of higher fatty alcohols. Additive consumption during the process makes 0.02-0.15% of absolutely dry wood weight.

EFFECT: acceleration of delignification process, increase in sulfate cellulose softness and ecological processes, pulldown of common and hazardous resin content in cellulose and high degumming provision.

2 tbl, 4 ex

Method of pulping // 2368716

FIELD: textiles; paper.

SUBSTANCE: method refers to sulphate pulping and can be used in pulp and paper industry. The method comprises cooking hardwood chip in alkaline cooking liquor in the presence of organic additive. SAA of non-ionic type - OS-20 compound is used as additive. This is a mixture of polyoxyethylene glycolic esters of higher fatty alcohols. Additive consumption during the process makes 0.02-0.15% of absolutely dry wood weight.

EFFECT: acceleration of delignification process, increase in sulfate cellulose softness and ecological processes, pulldown of common and hazardous resin content in cellulose and high degumming provision.

2 tbl, 4 ex

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