I bring to your attention your debut article in a new vein. It gives the general principles of the papermaking machine for a more comfortable entry of the translator in the topic.
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Paper machine Paper Machine) - Multisective aggregate continuous (continuous. ) actions on which from strongly diluted (diluted.) Water fibrous suspension (fibrous suspension.) get paper and some species cardon (board).
Distinguish 2 main types of paper machines: plateful / tables (fourdrinier Machine) used to generate major paper types, and round-the-clock / cylinder (vat Machine)where a limited assortment of paper and cardboard is manufactured. These types have different devices for release. paper masses (paper / Papermaking Pulp or Stock) on the grid (wire.) paper machine and motion (formation.) paper web, the design of the other nodes, as well as the technological process of paper manufacturing similar.
Finished paper mass concentration of about 3-4% with the pump is supplied ( feed) is mass preparatory department (stock Preparation Department) in machine pool (machine Chest), from where it comes to the paper machine. Constant stirring (aGITATION.) Masses in the machine pool achieve alignment the degree of grinding (beating./refining degree) and mass concentrations throughout the volume. Previously it is diluted turning water (white / Back Water) dehydration (dEHYDRATION) paper mass on the grid of the paper machine, to a concentration of 0.1-1.5% and is passed through cleaning (screening.) Equipment - narrowhead ( screen / Strainer.), centricleer (centricleaner), centriskrines (centriscreen.), etc., where various extraneous inclusions and coarse particles of mineral and fibrous origin are removed. From the cleaning equipment, the paper mass enters press box (hEADBOX.), which provides expiration (discharge.) mass with definite speed (rate.) and the same thickness jet (jet.) Over the entire width of the grid.

The paper machine consists of the following main parts:

• grid (wire Section.), where from the diluted suspension is continuously molded paper canvas (paper Web. ) and the first part is removed from it. excess water (excess Water. );
  
• press (press Section.) where dehydration and seal (compacting.) Paper linen:
  
• sushil (dryer Section.), in which the moisture remaining in the paper canvas is removed:
• finished (fINISHING SECTION) where the canvas is subjected to the necessary processing for giving loska. (glaze.), density (dENSITY.), smoothness (smoothness) I. wounds in rolls (wind to Reels ).

Grid part - Infinite mesh, pushed out of the threads of various alloys of copper or synthetic materials. Mesh drive is carried out from gaucher Vala (couch Roll). On new machines having vacuum resetting devices (vacuum Pick-Up Arrangement), drive is also the leading grid shaft. So that the paper mass does not flow, on the edges of the grid are installed restrictive rules (guides). Dehydration of the paper mass and molding of the paper sheets occur due to the free stocking and suction action (sUCTION) Register rollers ( table Roll). To obtain a more homogeneous paper cloth in longitian (machine/gRAIN DIRECTION.) I. transverse directions (c. rOSS DIRECTION ), at the speed of the machine not more than 300 m / min, the register part is sometimes exposed shake (shake) In the transverse direction. Further dehydration occurs over whiserboxes (sUCTION BOX.) under the action of a vacuum created by special vacuum pumps (sUCTION PUMP.). When developing high-grade papers (fine Paper.) Observe them often install light Equant roller (Dandy Roll). Equative roller serving to apply water signs (water Marks.) Called eguuter (Egoutteur.). After that, the paper canvas contains a relatively much moisture (88-90%), to remove which the mesh together with the blade passes over the gauch shaft, which has from one to three suctionery cameras (vacuum Chamber.). Gauch-shaft - perforated hollow cylinder (drum) From bronze alloy or stainless steel (perforation area is about 25% of the shaft surface). Inside the case is a fixed vacuum chamber with graphite seals, which pneumatically pressed to the inner surface of the cylinder. The vacuum chamber is connected to a continuously active vacuum pump. The gauch-shaft completes the molding and dehydration (up to dry 18-22%) of the paper web on the grid of the paper machine.

Further dehydration occurs in the presses Mechanical spinning under the action of pressure and vacuum by passing the web through several (2-3, less often 4-5) roller presses (roll Press), located consistently (often the first and second press are combined into dual press - tWO-ROLL PRESS). At the same time increase volumetric mass (specific density), thunderstanding properties (strength Properties.), transparency (transparency.) decrease porosity (porosity.) I. absorbing ability (absorption.) Paper. Pressing is performed between woolen Suknov (felt.), which protect still weak paper from destruction, absorb pressed moisture and simultaneously transport the canvas. Each press has its own cloth. On all new high-speed paper machines, bottom shafts are made perforated (perforated) (like gauch trees). They are covered Special rubber (rubber Cover.), which improves dehydration and increases the service life. On some paper machines instead nizhny Whiskers valls (bottom Roll) Install trees with special grooved rifer (gROOVED ROLL.). On powerful paper machines, the lower shafts of the first and second presses are made of suction (similar to the gauch shaft). Often, except for presses with clots, install more smoothing (or offset) presses (second Nip.) Without Sukon for sealing paper and giving it smoothness. Then the bars of paper with dryness up to 45% enters the drying part.

Drying part (The largest in length) consists of rotating heated from the inside of steam and usually located in 2 rows in checked cylinders. The canvas is pressed against the heated surface of the cylinders with the help of Sukon, improving the heat transfer and preventing the warming and wrinkling the surface of the paper during drying. The upper and lower rows of drying cylinders have separate cloths, and one cloth covers several drying cylinders(dryer Drum / Drying Cylinder). The paper canvas moves from the top cylinder to the lower, then to the next upper, etc. At the same time, the paper is dried to a residual moisture content of 5-7%. On modern paper machines in the second half of the drying part, the adhesive twin press press is usually placed ( size Press) For surface sizing paper and applying the surface layer.

Finishing part is a calender ( calender) consisting of 5-10 each other cast iron shafts (cast Chilled Iron Roll). Pre-paper to give it greater elasticity and softness is cooled and somewhat moistened on the refrigeration cylinder (cold water is supplied through the hollow cakes). When moving between shafts from top to bottom, the canvas becomes smoother, compacted and leveled in thickness. The paper is then covered with an endless ribbon into rolls on a forcibly rotating cylinder, to which the roller with the paper covered on it is grid (Reel). To moisture paper with additional finish of it on supercalandra (superCalender.) (To obtain paper with increased smoothness, gloss and volumetric mass) above the roller moisturizing apparatus (reetting Device.). Next, the roll is cut on longitudinal cutting machine (longitudinal Cutter.) On the necessary formats. At the same time, the paper is sorted, cliffs (break) There are arising when it is developed, glued together. When publishing paper in sheets, cutting rolls are supplied to the paper sheet cutting machine - selfless (sheeter / Sheet Cutter).

Purpose, device drying part of BDM and CDM

The process of drying paper and cardboard. Method of calculation

Numbers of drying cylinders, their layout in

Drying

Plan lectures

The characteristic of the drying part, its role in the general process of paper production. Possible methods of paper drying, their advantages, disadvantages. The mechanism of contact drying paper on the cylinders, contact drying factors. Methods for calculating the number of drying cylinders during the warm-up period in the first period, in the second period.

The possibility of eliminating the shrinkage of the paper canvas and the layout of the drying cylinders along the length of the drying part.

Drying part of machines producing sanitary types of paper.

After the presses, the dryness of the paper is usually from 28 to 45%. Further dehydration to finite dryness 92 - 95% occurs on the drying part of the paper machine. The amount of water evaporated here is determined by dry paper coming on the drying part and leaving it. It ranges from 1.3 to 2.5 kg of water by 1 kg of paper, which is about 50 to 100 times less than the amount of water removed on the wet part of the machine.

Of all parts of the paper machine, the drying part is the largest length. The number of drying cylinders, depending on the velocity of the machine, weight 1 m 2 and the type of paper, can be from 60 to 80 (with a diameter of 1500 mm). The weight of the drying part without taking into account the auxiliary equipment is approximately 60-70% of the weight of the high-speed machine, and the cost reaches 50% of the cost of the entire car. Operational costs associated with the work of the drying part are also significant: the cost of steam per drying and ventilation is 5 - 15% of the cost of paper; The power consumed by the drying part is approximately half the power consumed by the machine (without power spent by vacuum pumps). Removing water on the drying part is much more expensive than on the wet part. In this connection, the feasibility of the maximum possible increase in dryness of paper entering the drying part is obvious, since the steam consumption is reduced and the required number of drying cylinders decreases.

Currently, the main method of drying paper on the paper machine is the contact method. In order to avoid the formation of wrinkles (swinging), paper when dried should be pressed with cloves to cylinders.

Heating cylinders is carried out by water vapor. There are designs of drying cylinders heated by organic coolants, gas burners and electric heaters, but they have not yet found wide use.

The contact drying of the paper compared to other methods has a number of essential advantages, to the main of which should include high economic indicators and high quality of the dried web, in particular, high bilateral smoothness. On the drying part ends the cloak of paper canvas. For a good paper sizing, the temperature should be adjusted to 70 - 80 ° C, before the dryness of the paper reaches 50%.

The disadvantages of multi-cylinder drying should include high solid capacity (about two thirds of the mass of the entire car) and insufficient intensity of the process

In parallel with the contact drying, a convective drying of heated air is used in paper and carbonate machines. Despite the fact that with convective drying, energy costs are usually higher than with contact, it finds applied on all modern paper and cardinal machines.

The advantages of the convective method of drying should include the simplicity of constructive performance, the wide possibilities of regulating moisture in the width of the paper web, as well as in some cases, the greater intensity of the process compared to the contact dryer. The highest intensity of drying is achieved when the caps of the speed drying with a nozzle blowing the moving canvas are used.

Along with the contact and convective drying of moving webs, there are also combinations of the first two with drying in power fields, vacuum drying and drying with a heat-mechanical removal of moisture.

Recently, widespread use abroad for drying paper and cardboard has found devices with heat-mechanical deposit moisture. In this case, the drying method occurs not only evaporation of moisture due to heat supply, but also mechanical displacement and replacement of it in the pores of the material with a gaseous agent. Drying with airfront or gas has a very significant intensity. The intensity of drying is achieved about 140 kg / (m 2 × h), which is approximately 10 times higher than the average drying intensity in the multi-cylinder drying part.

In the process of contact drying, the contact heat exchange begins with a hot surface of the drying cylinder with a hot surface of the drying cylinder. A certain amount of heat is also transmitted by radiation, since there is absolutely complete contact between the paper and the surface of the cylinder.

The paper machine is a union of the production sections of a continuous action, as a result of which paper and cardboard are obtained from a fibrous suspension. Distinguish two types of this ...

Paper machine is Combining production sections of continuous action, as a result of which paper and cardboard are obtained from a fibrous suspension. There are two types of this unit: cutlery (with a flat grid) and cylinder (with a round grid).

More common dining paper machineWith which the main types of paper are manufactured.

The main sections of this design are: Grid, press, drying and finishing parts.

Grid part

The grid part is an infinite grid made of synthetic materials or various copper alloys. In this section, a paper canvas from a strongly diluted suspension is molded and the first part of excessive water is eliminated. These stages occur due to the free flow of the suspension and sucking effects of register rollers. In the future, dehydration is carried out with the help of special vacuum pumps.

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Press part

After passing the grid section, the paper cloth with dryness percentage of approximately 18-22% falls into the press section. Here is the removal of excess water with a mechanical spin. The paper is passed through the sequentially located 2-3 roller press under the simultaneous impact of vacuum and pressure. It increases its bulk mass and strength, and absorbing the ability and porosity, on the contrary, decrease. The pressing process occurs between the wool bits, which absorb moisture and transport the canvas, and also perform an important function of protecting the weak paper canvas from destruction. In order to achieve an increase in the density and smoothness of the paper often install additional smoothing presses.

Drying part

In the drying part of the paper, the paper comes with dryness of about 45%. This section of the paper machine consists of rotating cylinders located in a chess and heated steam. At this stage of production, the paper canvas with a sucon is attached to the preheated cylinders, which prevents it from wrinkling and warping. Its movement occurs from the lower cylinder to the top, then again to the lower, located near, etc. Paper in the drying part is dried to a humidity of 5-7%.

Finishing part

In the finishing section there are 5-10 cast-iron bleached shafts located over each other. Pre-moistened with cold water paper moves from top to bottom between shafts. After passing this stage, the paper canvas acquires a flat, smooth surface and a uniform thickness. To prevent crumpled cloth on the roller, wounds into rolls. If necessary, the release of high smoothness paper above the roller is installed additional moisturizing equipment. The obtained rolls further come to the longitudinal cutting machine, where they are cut into parts with the necessary parameters.

Special equipment

The paper machine is also equipped with a large number of automatic devices providing its continuous operation. The task of this additional equipment to adjust the technological parameters of the entire process. For the manufacture of various types of paper canvases, their technically informed parameters are installed, namely the operating speed and width of the machine. The paper machine can be narrow and wide.

Narrow vehicle widths from 1.6 to 4.2 m are mainly intended for the manufacture of special technical, high-quality document paper. Wide Machines with widths of the canvas more than 6 m are used for the production of bag and newsprint. The working speed of the paper machine in the production of newspaper and sanitary paper is significantly higher in the manufacture of high-quality types of papers. The presence of special equipment and automatic devices contributes to the accuracy of the papermaking machine and allows you to reduce the number of serving workers to 3-8 people.

Improving the production process

To further improve the paper production process, it is necessary to change the technology of production, an increase in machine performance due to the width and speed, upgrading the device of the machine and its nodes.

Increase the performance of the paper machine due to speed and widths will help:

• special high-speed streams distributors producing a fibrous suspension on the grid at the speed that is necessary when the grid speed has increased;
• hydras and register rollers that increase moisture removal;
• various types of presses such as hot and multiple presses, press with wide suction chambers;
• fixed in the middle of suction trees, grooved corrugated shafts, sucking vacuum cloth;
• peripheral type with a pneumatic clip of the paper canvases used to wind the roll of 2200-2500 mm in diameter.

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For the drying section of the paper machine, it can also be successfully used: Siphon elimination of condensate, new pair distributor location schemes, higher steam pressure, replacing the drying sucon on the drying grids. At present, there is an active search for new types of drying, in order to replace the traditional view to a more improved, which would increase the uniformity of the drying process and significantly reduce the work area of \u200b\u200bthe drying section. Such new types of drying, as infrared irradiation, blowing hot air, dielectric drying and drying under vacuum have good prospects in the future.

Principle of papermaking machine

The paper machine is used for the manufacture of paper from the fibrous mass by moving the fiber layer, followed by dehydration, pressing and winding into a roll. In Tsarist Russia, such aggregates began to be used from the second half of the XIX century. They differed low performance, weak water separation, manual control. For the repair required a stop of machines, but they had high reliability and simplicity of design. At the Slavish paper factory, such an aggregate was installed in 1864 and worked until the end of the twentieth century.

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Principle of operation of the car

There are 2 types of paper machine: dining room - fibrous mass is distributed on a flat infinite grid and cylinder - with a round grid. Mainly used table aggregates, cardboard and some types of paper are manufactured on the cylinders. The machine is made on the principle of consistently installed continuously active sections:

• grid;
• presses;
• drying;
• finishing.

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In addition, there are many auxiliary systems and mechanisms providing and controlling a continuous cycle of paper manufacturing. The speed of the paper sheets varies from 40 m / min during the production of fine condenser paper, up to 1000 m / min - newspaper. This is a very energy-intensive unit that consumes up to 30 MW of electricity and 45 tons of steam. AUTP is used to control the technological process. At such speeds, it is impossible to manually control and adjust the parameters.

The paper manufacturing process begins with a stage of the preparation of raw materials. For this purpose, a mixing chamber is used, which comes crushed and pre-purified from foreign objects that are not involved in the process (metal, stones, tape, etc.) components of paper - waste paper, rag. If a tree is used, then the pre-prepared chip is boiled in a solution of caustic substances until complete dissolution.

The finished mass is pumped by pumps from the mixing part to the pool of the papermaker. The concentration of the entered medium is 3-4%. A constant mixing of the solution occurs in the tank to maintain the homogeneous state of the paper mass throughout the volume. The flow of circulating water containing the inclusion of cellulose is adjusted by the concentration of the prepared solution to 0.15-1.5%, it is sent to the treatment equipment. This uses nodesters, centrcrins and others. After that, the paper mass through the intake device comes to the grid.

The quality of the material is made depends on the synchronization of the speeds of the mesh and the expiration of the suspension. The lagging for moving mass from the grid should not exceed 5-10%. The deviation of the parameters in one or the other side leads to an uneven distribution of fibers along the area of \u200b\u200bthe mesh and their orientation towards the movement of the web. This is reflected on the density, homogeneity and strength of manufactured products.

Paper formation

The leaf tump is a filtration process, in which water removed, a fibrous layer is formed. After passing the register part of the mesh table, a canvas with a mass concentration of about 3% is formed. Upon reaching such values, the "bay mirror" ends and the concepts of "paper, paper canvas" and its dryness are introduced. The process of motion is most intensively in the register part located in the first third of the table. The errors allowed at this stage will no longer be corrected during the manufacture of paper and will be a defect.

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The quality of the papers and the position of the fibers relative to the direction of flow movement depend on the nature and concentration of the mass, the speed of the mesh and the expire of the colloidal solution, the intensity of water filtration. In turn, these parameters depend on and are determined by the appointment of manufactured products.

In some cases, it becomes necessary to increase the speed of dehydration of the web, for example, to prevent flocculation, that is, the formation of fiber bunches. The concentration of mass is largely affected by the flow of this process. At low values, active water filtration occurs, which largely reduces the likelihood of flocculation.

On the other hand, too abundant water supply leads to a flushed of fibers, especially small fractions. Intensively, this process occurs in the initial stage of leaf formation. Ultimately, this leads to a decrease in the content of the filler in the lower (grid) side of the sheet. This defect is eliminated by reducing the filtering rate.

Changing the intensity of water supply occurs with increasing sheet thickness and filter resistance. This leads to the need to apply forced methods of dehydration of the fibrous layer. For this, suction boxes are applied. They create a vacuum with special pumps, allowing to remove moisture, which did not have time to drain in the initial stage of paper.

The grid table ends with a device called suction gauch. A 30-70 kPa vacuum is supported in its camera, which makes it possible to effectively suck moisture. Under the gauch-shaft is a bath in which water drops and a discharge of the so-called wet marriage. These are the cut-off edges of the paper canvase, breakfasts from the press part, the contents of the grid table when the paper breaks. A mixer, located in the bath, transmits a mixture to pumping pumps that return the solution into the receiving tank to recycle.

Press part

After the gauch shaft, the paper canvas with dryness 15-20%, a vacuum transmitting device is transmitted to the press part of the paper machine for further mechanical dehydration. It usually consists of 2-3 dual-hole presses. The upper shaft is made of granite, lower - metallic, lined with rubber. Between them, together with the paper blade, the cloth moves, protecting the surface of the wet paper from damage.

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The design of the press mechanism allows the use of a consistent passage of different sides of the canvas between the shafts. This ensures uniform smoothing of both sides of the paper. To remove the fibers sticking to the canvase, a cloth is used. After the consistent passage of the press part, the dryness of the paper is 30-40%.

In this section of the machine, not only dehydration occurs, but also the seal of the canvas. At the same time, the area of \u200b\u200bcontact and the grip between the fibers increases. In addition, paper properties change: the strength increases, the porosity decreases, transparency increases, etc. The press part should work with full load, since the increase in dryness by 1% allows to reduce the steam consumption for the drying cylinder heating by 5%. The intensification of these processes can significantly reduce the overall energy consumption, which ultimately affects the cost of products.

Drying paper web in the press part is 10 times cheaper than in the dryer. Of the total remote water, about 95% falls on the net, 3-4% per press, and the rest is on the drying. Therefore, the first 2 parts are called wet. To remove the remaining 1-2% moisture, most of the energy intended for dehydrating the paper canvases.

Drying part

This section of the machine consists of 2 rows of sequentially unfolded cylinders covered by drying cloth. The device of the drying cylinder is a hollow cylindrical container heated from the inside by steam. The pressure of the working medium is 0.35 MPa. The diameter of the drying cylinder is 1500 or 1800 mm and depends on the type of paper manufactured.

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The number of cylinders depends on the type of product produced and the speed of the machine. For the manufacture of condenser paper, 5-8 drums are installed, and for newspaper and sages - 50-80. Drying cylinders are combined in 3-5 independent groups, which allows separate adjustment and maintenance of temperature in separate blocks. Paper and Sukon Movement Scheme ensures heating and evaporation of moisture not only with its contact with the heating surface of the drying cylinder, but also during the free stroke. The use of an individual drive for each of the groups allows you to synchronize the speeds of neighboring blocks to ensure the bumping movement of the paper web.

Each group provides for the installation of a drying cylinder for Sukon, intended not only to absorb moisture, but also transporting the paper web along this part of the unit. In the machines with a high speed of the paper movement, the drying part is completely covered with a cap, allowing to maintain heat without additional use of energy. It is equipped with a system forced ventilation and heat exchanger-recuperators. Heated wet air, before will be thrown into the atmosphere, heats the supplied medium to its heat, which is fitted on the heat exchanger and enters the canvas blowing.

Depending on the type of paper produced, the temperature of the cylinders is 80-115 ° C. In the process of drying, 1 kg of paper is removed to 2.5 liters of moisture, which is 60-80 times less than on the grid and press parts of the machine. The increase in the heating rate of the drums accelerates the drying process, so it must be carried out at maximum values \u200b\u200bof this parameter that does not affect the quality of the finished product. In the drying caps of high-speed machines, a nozzle blowing the canvas with heated air is used. This accelerates the dehydration process and reduces energy costs.

The finishing part consists of Calandra and Nakat. It is installed between the drying part and rolling and consists of 5-8 horizontally located shafts. The lower is driven and provide the passage of paper between them. At the same time, it is additionally compacted and smoothed. On the roll, the paper is formed into rolls by weight or diameter and in the future goes on the cutting.

On this process of paper production ends. The use of advanced technologies and automation of the manufacturing process, at the speed of movement of the canvas 1000 m / min and more, allowed to reduce the maintenance of the unit to 5-8 people.

The papermaker BDM-10 is designed to produce various types of paper: wallpaper, printed, for food packaging. In the manufacture of paper, the paper machine is an independent unit, the main nodes of which are installed strictly consistently along the mounting axis.

Technical characteristics of paper machine

The technical characteristics of the papermaker BDM-10 is given in Table 2.1. The general scheme of BDM-10 is shown in Figure 2.1

Table 2.1 - Technical Specification BDM-10

Name of parameter	Value
Width of the canvas, mm: On the russian Edged width
Products - paper base for wallpaper mass, g / cm2
Performance, kg / hour
Speed, m / min: By driving Auxiliary
Limit of stable control of the electric drive
Performance when working out the calculated type of paper weighing 150 g / m2, kg / hour
Linear load in the lower grip of the shafts of Calandra, KN / M: From the weight of the shafts with the removal console parts The greatest when working with an additional clamp
The minimum length of the grids 1 of the drying group after modernization, m: Upper

Figure 2.1 - Paper Machine Scheme BDM-10:

1 - pressure box; 2 - grid part; 3 - press part; 4 - drying part; 5 - calender; 6 - Nakt

Composition of papermaking machine

BDM includes: pressure box, grid, press and drying parts, calender and rolling. It also belongs to the machine swimming pool for mass, equipment for its purification, pumps for water supply and mass, vacuum pumps, marriage processing devices, equipment for circulation lubrication, supply and exhaust ventilation system, regulating and measuring instruments, etc. 1. The circuit of the pressure drawer of the closed type is presented in Figure 2.2.

Figure 2.2 - Pressure box:

1 - collector-flow distributor; 2 - perforated stove; 3- perforated shafts; 4 - case of a box; 5 - front wall; 6 - slot control mechanisms; 7 - defoamer; 8 - Airbag

Press box is designed:

To distribute the stream of suspension when sculpting the machine with the same consumption and speed by the width of the molded canvas;

Transmit a suspension to the graduation slot without falling out of the fibers and without the appearance of transverse jets;

Return a fibrous suspension with a certain speed with high-intensity turbulence and a small scale to the grid of the machine.

The grid part is designed to form a paper web with a suspension concentration of 0.1 - 1.3%. The fiber filtering process from the suspension and molding of the canvas on the grid part occurs at a relatively short portion of the table and is determining in obtaining quality paper indicators. The main element of the grid part is one endless grid, stretched between shafts. The grid part of the BDM is shown in Figure 2.3.

Figure 2.3 - Grid part:

1 - pressure box; 2 - breast shaft; 3 - forming drawer; 4 - hydroplane box; 5 - wet suction box; 6 - register shaft; 7 - suction box; 8 - suction shaft; 9 - presenter; 10 - Networking; 11 - Networking shaft; 12 - Set Matching; 13 - Mesh.

The pressing mechanism is determined by the amount of water removed and the uniformity of the paper linen. Dehydrating ability depends on the contact zone of shafts and on the number of these zones. When pressing, the structure of the web also changes, the structure of paper will increase, its thickness, density, air permeability, opacity and other properties will change. In the press part should be provided: 1) the maximum dehydration of the paper sheet to obtain a given physicomechanical properties; 2) uniform moisture content of the width of the width; 3) Bearing cloth wiring with minimal sections of free stroke.

The press part of the paper machine is shown in Figure 2.4.

Figure 2.4 - Press part of the paper machine:

1 - grain shaft; 2 - suction shaft; 3 - shaft rubberized; 4 - sleek shaft; 5 - presenter; 6 - suction shaft; 7 - clamping shaft; 8 - Gunner shaft; 9 - Suknopravka; 10 - SUKNOTAYA; 11 - Sukno

The drying part is designed for dehydration (drying) of the paper canvase. The drying part consists of drying cylinders heated by steam. They are placed in a checkerboard in two tiers. On the drying cylinders, the paper canvas passes, alternately in contact with the bottom and upper cylinders, then the other surface. Sukon tension and their editing are carried out by robes, clunk and suction rollers equipped with the necessary mechanisms. Sukon drying is provided by closet cylinders and suction rollers.

The diagram of the drying part is shown in Figure 2.5.

Figure 2.5 - Drying part:

Calander is designed to achieve the required smoothness, density and uniformity of the thickness of the canvas while other quality indicators are met as given limits. Calandon consists of: metal shafts; the beds in which the bearings housings and the trees levers are placed; Drive for rotation of the bottom shaft; The mechanism of lifting and device of additional clips of shafts. The drive shaft transmits the rotational movement of adjacent shafts thanks to friction forces.

Below is the Calandra scheme in Figure 2.6.

Figure 2.6 - Calandine:

1 - the mechanism of clips and lifting shafts; 2 - bed; 3 - intermediate shafts; 4 - lower (indigenous) shaft

Figure 2.7 - Ranat:

1 - coiled roll; 2 - bed; 3 - the cylinder of the commission; 4 - tambourine roller; 5 - receiving levers; 6 - Pneumatic cylinder Tambura: 7 - Resection roller; 8 - refueling rope; 9 - the cylinder of the rotation of the receiving levers; 10 - cylinder of the drive of the main levers; 11 - main levers; 12- brake device roll; 13 - damper

Ranat is designed for uniform and dense winding of a paper canvase in rolls. The higher the quality and uniform density of the winding of rolls, the better the cutting process on longitudinal-cutting machines. Scheme is shown in Figure 2.7.

Ranat includes: the cylinder of the commission; Tambourous shafts; receiving levers; Workers levers, holding a tambour shaft winding the web, and the mechanisms of the drive of the rotation of the receiving and working levers.

Description of the papermaking machine

Basic operations: accumulation of paper mass; scab in mass on the grid; molding paper cloth on the grid; pressing; drying; Machine trim and paper winding into roll 3.

Prepared paper weight with a concentration of 2.5 - 3.5% is supplied to the machine pool with a circulation device. For better concentration, it is additionally crushed with conical and disk mills. Next, the mass of 0.1 concentration is 1.3% is supplied to the pressure box.

The grid part serves to slow down and molding a paper web to remove the excess moisture from the paper mass. When the grid passes through its maintaining register rollers and hydroplacs, the paper mass is dehydrated to a concentration of 2-4%. Further dehydration occurs on suction boxes under the action of vacuum to a concentration of 8 - 1.2%. Also dehydration occurs on the gauch-shaft under the action of a vacuum in the suction chamber. The dryness of the paper canvase after the grid part is 12 - 22%.

Further, the paper canvas enters the press part, where it is dehydrated to dryness 30 - 42%. The press consists of two shafts, of which the lower is suction. Between the press shafts, an infinite, supported by soft rollers cloth, which transports the paper canvas. The molded canvas automatically vacuum transmitting device is transmitted to a cloth press part. The press part makes it possible to ensure the passage of paper, where the cloth is constantly maintained, therefore, allows you to carry out puppy paper wiring into the press part.

The drying part of the BDM consists of drying cylinders heated by steam. They are placed in a checker, in two tiers. When the drying part is passed, the paper canvas, in contact, first with the bottom cylinder, and then with the upper one, then the other surface. The tension of Sukon and their editing are carried out at the expense of the guards, clunrics and suction rollers. Suchness after the drying part is 92 - 95%, and the temperature is 70 to 90 ° C. At the end of the drying, refrigeration cylinders are installed. When cooled, the paper absorbs moisture and moisturizes 1 - 2%. Further, the paper canvas passes through the machine calender for sealing and rising smoothness consisting of eight shafts. Caalender machine is equipped with a presser, lifting and slight mechanism. Further, when Calandine passages, paper is wound on tambourines into a roll with a diameter of up to 2500 mm. Recycle is made using special mechanisms and devices. In the future, paper cuts on specialized machines and is cheated.

drying paper machine

In the drying part of the paper machine, the paper sheet is dehydrated to a finite dryness of 92 - 95%. During the drying process, 1.5 - 2.5 kg of water per 1 kg of paper is removed, which is about 50 to 100 times less than on the grid and press parts of the machine. When drying at the same time, further sealing and rapprochement of fibers occurs. As a result, the mechanical strength and smoothness of the paper increases. From the drying mode, bulk weight, absorbing ability, breathability, transparency, shrinkage, moisture resistance, degree of sizing and paper painting are dependent.

The drying of the paper on the drying cylinder consists of two phases: on the heated surface of the cylinder under the cloth and on the free stroke site, i.e. when the paper canvas moves from one cylinder to another. In the first phase, under the cloth, the main amount of moisture evaporates: on low-speed machines up to 80 - 85%, on high-speed up to 60 - 75% of all moisture, evaporated in the drying part of the car. In the second phase, in the sections of the free move moisture evaporates on both sides of the paper due to heat absorbed by paper in the first phase of the drying. In this paper, depending on the speed of the machine undergoes a decrease in temperature by 4 - 15 ° C. When the temperature drops, the drying speed is reduced, especially on the low-speed machines, since they drop the temperature of the paper canvas is greater than on the high-speed machines. With an increase in the velocity of the machine, the amount of evaporated water on the free stroke of paper increases. With a decrease in the amount of water in the paper canvas, the drying intensity on the free plot is down.

The temperature of the drying cylinders increases gradually, which contributes to improving the quality of the paper and the completion of the crunch process. At the end of the drying part, the surface temperature of the cylinders is reduced, as the high temperature at a small paper humidity acts on the fiber destructively.

The wet paper canvas, directed with the press part of the paper machine, is refilled between the heated surface of the first drying cylinder and the drying grid (cloth). At the initial section of the movement, the drying mesh (cloth) accompanies the dried canvas in the free plot between the upper drying cylinders and the lower vacuum rollers. This is a feature of this paper blade refueling scheme. This refueling reduces the risk of paper cloth break.

The drying cylinders are hermetically closed with a ventilation cap, from which the removal of spent wet air is removed. A portion of the exhaust air in the heater is mixed with fresh shop air, heats up in the calorifer and the duct air duct is supplied to the drying part of the BDM through the air distribution channels. Exhaust and workshop air, water from a scrubber, headed for general ventilation of the workshop. Dried to conditioned paper linen after processing in the calender is wound into the roll roll.