Basic calculations for the mass preparation department. Equipment for the preparation and production of paper pulp General technological scheme of waste paper processing

Ministry of Education of the Russian Federation

Perm State Technical University

Department of TCBP

Group TTsBPz-04

COURSE PROJECT

Topic: "Calculation of the mass preparation department of the paper machine that produces paper for corrugating"

Akulov B.V.

Perm, 2009

Introduction

1. Characteristics of raw materials and finished products

Introduction

Paper is of great national economic importance, and its production. Paper production technology is complex, as it is often associated with the simultaneous use of fibrous semi-finished products of different properties, a large amount of water, heat and electricity, auxiliary chemicals and other resources and is accompanied by the formation of a large amount of industrial waste and effluents that adversely affect the environment. .

Assessing the general state of the problem, it should be noted that according to the European Confederation of Paper Producers (CEPI), since the beginning of the 90s, the volume of waste paper recycling in the world has increased by more than 69%, in Europe - by 55%. With a total stock of waste paper mass estimated at 230-260 million tons, about 150 million tons were collected in 2000, and by 2005 the collection is projected to increase to 190 million tons. At the same time, the average world level of consumption will be 48%. Against this background, the figures for Russia are more than modest. The total resources of waste paper are about 2 million tons. The volume of its procurement has been reduced compared to 1980 from 1.6 to 1.2 million tons.

Against the backdrop of these negative trends in Russia, the developed countries of the world over these 10 years, on the contrary, have increased the degree of state regulation in this area. In order to reduce the cost of products using waste, tax incentives were introduced. To attract investors to this area, a system of preferential loans has been created, in a number of countries restrictions are imposed on the consumption of products manufactured without the use of waste, and so on. The European Parliament has adopted a 5-year program to improve the use of secondary resources: in particular paper and cardboard up to 55%.

According to some experts from industrialized countries, at present, from the point of view of the economy, it is advisable to process up to 56% of waste paper from the total amount of waste paper. In Russia, about 35% of this raw material can be collected, while the rest of the waste paper, mainly in the form of household waste, ends up in a landfill, and therefore it is necessary to improve the system for collecting and harvesting it.

Modern technologies and equipment for the processing of waste paper make it possible to use it not only for the production of low-quality, but also high-quality products. Obtaining high-quality products requires the presence of additional equipment and the introduction of chemical auxiliary substances to improve the mass. This trend is clearly visible in the descriptions of foreign technological lines.

The production of corrugated cardboard is the largest consumer of waste paper and its main component is old cardboard boxes and boxes.

One of the decisive conditions for improving the quality of finished products, including strength indicators, is to improve the quality of raw materials: sorting waste paper by brand and improving its cleaning from various contaminants. The increasing degree of contamination of secondary raw materials adversely affects the quality of products. To increase the efficiency of using waste paper, it is necessary to match its quality to the type of products produced. So, containerboard, corrugating paper should be produced using waste paper, mainly MS-4A, MS-5B and MS-6B grades in accordance with GOST 10700, which ensure the achievement of high product performance.

In general, the rapid growth in the use of waste paper is due to the following factors:

Competitiveness of production of paper and cardboard from recycled raw materials;

Relatively high cost of wood raw materials, especially considering transportation;

Relatively low capital intensity of projects of new enterprises operating on waste paper, in comparison with enterprises using primary fibrous raw materials;

Ease of creating new small enterprises;

Increased demand for recycled fiber paper and board due to lower cost;

Government legislation (future).

It should be noted another trend in the field of waste paper processing - a slow decrease in its quality. For example, the quality of Austrian containerboard is constantly declining. Between 1980 and 1995, the bending stiffness of its middle layer decreased by an average of 13%. The systematic repeated return of the fiber to production makes this process almost inevitable.

1. Characteristics of raw materials, finished products

The characteristics of the feedstock are shown in Table 1.1.

Table 1.1. Brand type and composition of waste paper used for the production of paper for corrugating

Waste paper brand
	Kraft paper	Waste paper production: packaging twine, electrical insulating, cartridge, bag, abrasive base, adhesive tape base, and punched cards.
	Non-moisture resistant paper bags	Used bags without bituminous impregnation, interlayer, reinforced layers, as well as residues of abrasive and chemically active substances.
	Corrugated cardboard and packaging	Waste paper and cardboard production used in the production of corrugated cardboard, without printing, adhesive tape and metal inclusions, without impregnation, coating with polyethylene and other water-repellent materials.
	Corrugated cardboard and packaging	Wastes from the production and consumption of paper and cardboard used in the production of corrugated cardboard with printing without adhesive tape and metal inclusions, without impregnation, coating with polyethylene and other water-repellent materials.
	Corrugated cardboard and packaging	Waste paper and cardboard, as well as used corrugated packaging with printing without impregnation, coating with polyethylene and other water-repellent materials.

2. Selection and justification of the technological scheme of production

The formation of the paper web takes place on the wire table of the paper machine. The quality of the paper to a large extent depends on both the conditions of receipt on the grid and the conditions of its dehydration.

Characteristics of PM, composition.

In this course project, a mass preparation department for a paper machine producing paper for corrugating weighing 1 m 2 100 - 125 g, speed - 600 m / min, cutting width - 4200 mm, composition - 100% waste paper will be calculated.

Main design decisions:

UOT installation

Advantages: due to the repeated successive passage of waste from the first stage of cleaning through other stages, the amount of good fiber in the waste is reduced and the amount of heavy inclusions to the last stage of cleaning increases. Waste from the last stage is removed from the plant.

SVP-2.5 installation

Advantages:

· supply of the sorted suspension to the lower part of the body excludes hit of heavy inclusions in a sorting zone that prevents mechanical damages of a rotor and a sieve;

· heavy inclusions are collected in the collection of heavy waste and removed as they accumulate during sorting;

· in the sorting, a semi-closed rotor with special blades is used, which makes it possible to carry out the sorting process without water supply to dilute the waste;

· mechanical seals made of siliconized graphite are used in the sorting, which ensures high reliability and durability of both the seal itself and the bearings.

Parts of the screens that come into contact with the processed suspension are made of corrosion-resistant steel of the 12X18H10T type.

Installation of a hydrodynamic headbox with control of the transverse profile by a local change in the mass concentration

Advantages:

· the range of regulation of the mass of 1 m 2 of paper is greater than in conventional boxes;

· the mass of 1 m 2 of paper can be changed by sections by division of 50 mm, which improves the uniformity of the transverse profile of the paper;

· Zones of influence of regulation are clearly limited.

The method of making paper on flat-grid paper machines, despite the wide distribution and significant improvement in the equipment and technology used, is not without drawbacks. They were noticeably manifested when the machine was running at high speed, and such in connection with the increased requirements for the quality of the paper being produced. A feature of paper produced on flat-grid paper machines is a certain difference in the properties of its surfaces (versatility). The mesh side of the paper has a more pronounced mesh print on its surface and a more pronounced orientation of the fibers in the machine direction.

The main disadvantage of the conventional formation on one grid is that the water moves in only one direction and therefore there is an uneven distribution of fillers, small fibers across the thickness of the paper. In that part of the sheet that is in contact with the mesh, there is always less filler and fine fractions of fibers than on the opposite side. In addition, at machine speeds above 750 m/min, due to the action of the built-in air flow and the operation of the dewatering elements at the beginning of the wire table, waves and splashes appear on the stock loading mirror, which reduce product quality.

The use of dual wire forming devices is connected not only with the desire to eliminate the versatility of the produced paper. When using such devices, the prospects for a significant increase in the speed of the PM and productivity have opened up, because. at the same time, the speed of the filtered water and the filtration path are significantly reduced.

When using double-grid forming devices, such features are improved printing properties, reduced dimensions of the wire part and power consumption, simplified maintenance during operation, and a greater uniformity of the mass profile of 1 m 2 papers at a high speed of the PM. The Sim-Former forming device accepted in practice is a combination of a flat and two-wire machine. At the beginning of the formation of the paper web is due to the smooth removal of water on the forming board and subsequent single adjustable hydrobars and wet suction boxes. Its further molding takes place between two grids, where, first, above the arcuate surface of the waterproof molding shoe, water is removed through the upper grid, and then into suction boxes installed from below. This ensures a symmetrical distribution of fine fibers and filler in the cross section of the paper web and its surface properties on both sides are approximately the same.

In this course project, a flat mesh machine was adopted, consisting of: a console table, a chest, mesh-turning and mesh-guiding shafts, a suction couch shaft, a forming box, dehydrating elements (hydroplank, wet and dry suction boxes), scrapers, mesh straighteners, mesh stretchers, sprinkler systems, walkways service.

In the paper industry, the choice of cleaning and sorting equipment is also of great importance. Pollution of the fibrous mass has a different origin, shape and size. Depending on the density, the inclusions found in the mass are divided into three groups: with a density greater than the density of the fiber (metal particles, sand, etc.); with a density less than the density of the fiber (resin, air bubbles, oils, etc.); with a density close or equal to the density of the fiber (chips, bark, fire, etc.). The removal of the first two types of contaminants is the task of the cleaning process and is carried out at the FEP, etc. The separation of the third kind of inclusions is usually a task of the sorting process carried out in sorts of various types.

Cleaning of the mass at the FEP is carried out according to a three-stage scheme. Modern FEP designs have a completely closed system, operate with backpressure at the waste outlet, when used in front of the PM, they are also equipped with mass deaeration devices or work together.

Pressure screens are closed type screens with hydrodynamic blades used for such and coarse screening of pulp. A distinctive feature of this type of sorting is the presence of blades of a special profile designed for cleaning sieves.

Sorting type UZ - single-carrier with hydrodynamic blades, located in the zone of the sorted mass. These screens are mainly used for fine screening of UHC-cleaned stock immediately before the paper machine. Sorting type STsN are installed for sorting waste from the knotter.

3. Calculation of the material balance of water and fiber on a paper machine

Initial data for calculation

Corrugating Paper Composition:

Waste paper 100%

Starch 8 kg/t

The initial data for the calculation are presented in Table 3.1

Table 3.1. Input data for calculating the balance of water and fiber

Name of data	Value
1. Paper composition for corrugating, %
waste paper
2. Dryness of the paper web and mass concentration in the course of the technological process,%
waste paper coming from the pool of high concentration
in the receiving pool of waste paper
in the machine pool
in pressure overflow tank
at the third stage of centric cleaners
at the 2nd stage of centrikliners
waste after III stage of centric cleaners
waste after II stage of centric cleaners
waste after the 1st stage centric cleaners
knotter waste
vibration sorting waste
for vibration sorting
sorted mass from vibration sorting to the recycled water collector
in head box
after the preliminary dehydration section
after suction boxes
after couch shaft
cut-offs and marriage with couch-shaft
after the press part
marriage in the press
after the dryer
marriage in the drying part
marriage in decoration
after rolling
after slitting machine
in a couch mixer
in pulpers
reverse marriage after thickener
from the concentration regulator of the recycling pool
3. The amount of paper rejects from paper production, net, %
in finishing (from machine calender and rolling)
in the dryer
in the press section
cut-off and wet marriage with couch - shaft
4. The amount of sorting waste from the incoming mass,%
from knotter
from III stage centric cleaners
from II stage centric cleaners
5. Concentration of circulating water %
from couch shaft
from the press part, squeezed water into the drain
from the press part, water from washing the felts into the drain
from suction boxes
from the pre-drainage area to the under-grid water collector
from the preliminary dehydration section to the recycled water collector
from the thickener to the surplus recycled water collector
6. Mass overflow,%
from the headbox
from pressure overflow tank
7. Cellulose consumption per sublayer, kg
8. The degree of fiber trapping on the disc filter,%
9. Consumption of fresh water, kg
for defoaming in the headbox
for mesh washing
for washing cloths
for cutoffs
to the thickener

Longitudinal - cutting machine

Freewheel b/m

dry marriage in pulper

The amount of dry waste is 1.8% of the net output, i.e.

Check substance water mass

consumption: to the warehouse 930.00 70.00 1000.00

marriage 16.74 1.26 18.00

Total 946.74 71.26 1018.00

arrival: rewind 946.74 71.26 1018.00

Machine calender and reel (finishing)

dry marriage in pulper

The amount of dry marriage from the calender and reel is 1.50% of the net output, i.e.

Check substance water mass

Total 960.69 72.31 1033.00

Drying part

from the press section

The amount of dry rejects is 1.50% of the net output, i.e.

Check substance water mass

consumption: per calender 960.69 72.31 1033.00

Total 974.64 1329.47 2304.11

We accept that the dryness of the cloths after washing does not change, then with a content of 0.01% fiber in the drains, their total mass will be 4000.40 kg. Fiber loss with these waters is 4000.40-4000=0.4 kg.

Wet scrap from the couch shaft is 1.00% of the net output,

those. at 7.00% humidity

The cutoffs are 1.00% of the net output, i.e.

at 7.00% humidity

on the couch shaft

for suction boxes

The overflow into the under-grid water collector is 10.00% of the incoming mass,

The amount of waste from the knotter is 3.50% of the incoming mass, i.e.

Waste dilution unit for vibration sorting

The amount of waste from vibration sorting is 3.00% of the incoming mass, i.e.

We accept the amount of waste from the III stage of FEP - 2.00 kg. Waste from the III stage of FEP is 5.00% of the incoming fiber

The concentration of recycled water in the collection

Waste from the II stage of FEP is 5.00% of the incoming fiber, i.e.

to the II stage of the UOT

on the knotter

on the I step

Check substance water mass

Overflow is 10.00% of the incoming mass, i.e.

into the pulse mill

into a marriage thickener

in the pool of wet marriage

because then

The degree of fiber capture on the disc filter is 90%, i.e.

on the concentration regulator of the recycled marriage pool

into the composite pool

into pressure overflow tank

machine pool

We calculate starch, with a concentration of 10 g / l

B 4 =800 - 8=792kg

In table. 3.2 shows the consumption of clarified water.

Table 3.2. Clarified water consumption (kg/t)

The excess of clarified water is

Fiber loss with clarified water is

The summary balance of water and fiber is presented in Table. 3.3.

Table 3.3. Summary table of water and fiber balance

Items of income and expense
Fiber + chemical composition (absolutely dry matter):
waste paper
Cellulose per sublayer
finished paper
Fiber with water from presses
Vibration sorting waste
Waste from III stage of centrikliners
Fiber with clarified water
with waste paper
with cellulose on the sublayer
with starch glue
for washing cloth
for cutoffs
for sealing the vacuum chambers of the couch shaft
for sealing suction boxes
for mesh cleaning
for defoaming
to the thickener
in finished paper
evaporates when dry
from presses
with waste from vibration sorting
with waste from the III stage of centrikliners
clarified water

The irretrievable loss of fiber is

Wash fiber is

The consumption of fresh fiber per 1 ton of net paper is 933.29 kg of absolutely dry (waste paper + cellulose per sublayer) or air-dry fiber, including cellulose - .

4. Calculation of stock preparation department and machine performance

Calculations for the mass preparation department of the paper machine producing paper for corrugating:

Weight 1m 2 100-125g

Speed ​​b/m 600 m/min

Cutting width 4200 mm

Composition:

Waste paper - 100%

The maximum calculated hourly productivity of the machine in continuous operation.

B n - the width of the paper web on the reel, m;

V - maximum operating speed, m/min;

q - maximum weight of 1m 2 paper, g / m 2;

0.06 - multiplier for converting minute speed into hourly speed and paper weight.

Maximum calculated output of the machine (gross output) during continuous operation per day

Average daily machine output (net output)

K eff - coefficient of efficiency of machine use

K EF \u003d K 1 K 2 K 3 \u003d 0.76 where

To 1 - the coefficient of use of the working time of the machine; at V<750 = 0,937

K 2 - coefficient taking into account the marriage on the machine and the idling of the machine, \u003d 0.92

K 3 - technological coefficient of use of the maximum speed of the machine, taking into account its fluctuations associated with the quality of semi-finished products and other technological factors, for mass types of paper = 0.9

Annual productivity of the machine

thousand tons/year

We calculate the capacity of the pools based on the maximum amount of mass to be stored, the required storage time of the mass in the pool.

where M is the maximum amount of mass;

P H - hourly productivity;

t - mass storage time, h;

K - coefficient taking into account the incompleteness of filling the pool = 1.2.

High concentration pool volume

Composite pool volume

Receiving basin volume

Machine pool volume

The volume of the wet reject pool

Dry waste basin volume

The volume of the reverse marriage pool

The characteristics of the pools are shown in table 4.1.

Table 4.1. Characteristics of the pools

For the correct choice of the type and kind of grinding equipment, it is necessary to take into account the influence of factors: the place of the grinding apparatus in the technological scheme, the type and nature of the grinding material, the concentration and temperature of the mass.

For the processing of dry rejects, a pulper with the required maximum capacity is installed (80% of the net output on the machine)

349.27 H 0.8= 279.42 t

We accept GRVn-32

For marriage from the finish, a hydraulic pulper GRVn-6 is installed

Specifications are shown in table 4.2.

Table 4.2. Technical characteristics of pulpers

Cleaning plants

We accept UOT 25 at the first stage

Specifications are shown in table 4.3

Table 4.3. Technical characteristics of UOT

knotter

We accept SVP-2.5 with a capacity of 480-600 tons / day, technical characteristics are indicated in table 4.4

Table 4.4. Technical specifications

Parameter
Mass productivity according to w.s.v. sorted suspension, t/day, at the mass concentration of the incoming suspension:
The area of ​​the side surface of the sieve drum, m 2
Electric motor power, kW
Nominal passage of branch pipes DN, mm:
Suspension supply
Suspension withdrawal
Removal of light inclusions

vibration sorting

We accept VS-1.2 productivity 12-24 t/day

Specifications are shown in table 4.5.

Table 4.5. Technical specifications

Parameter
Mass productivity according to w.s.v. sorted suspension (paper pulp sorting waste with a sieve hole diameter of 2 mm), t/day
Mass concentration of the incoming suspension, g/l
Sieve area, m 2
Electric motors: - quantity - power, kW
Nominal passage of nozzles DN, mm: - supply of the suspension - removal of the sorted suspension
Overall dimensions, mm
Weight, kg

Calculation of centrifugal pumps

High Concentration Pool Pump:

receiving basin pump:

composite pool pump:

machine basin pump:

wet marriage pool pump:

dry reject pool pump:

mixing pump #1:

mixing pump #2:

mixing pump no. 3:

under-grid water collector pump:

circulating water collector pump:

couch mixer pump:

The main technical and economic indicators of the workshop

Electricity consumption kW/h…………………………………………………………………. .......275

Steam consumption for drying, t……………………………………………3.15

Fresh water consumption, m 3 / t…………………………………………23

water fiber paper machine

List of information sources used

1. Technology of paper: lecture notes / Perm. state tech. un-t. Perm, 2003. 80s. R.H. Khakimov, S.G. Ermakov

2. Calculation of the balance of water and fiber on a paper machine / Perm. state tech. un-t. Perm, 1982. 44 p.

3. Calculations for the mass preparation department of a paper mill / Perm. state tech. un-t. Perm, 1997

4. Paper technology: guidelines for course and diploma design / Perm. state tech. un-t. Perm, 51s., B.V. Sharks

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To category:

Wood pulp production

Thickening of the mass and the device of thickeners

The mass concentration after sorting is low - from 0.4 to 0.7 . Operations in the preparatory department of the paper mill - concentration control, composition and accumulation of some stock in the pools should be carried out with a denser mass. Otherwise, pools of very large capacity would be required. Therefore, a good mass after sorting is sent to thickeners, on which it is thickened to a concentration of 5.5-7.5'. During the thickening of the mass, most of the warm water entering the circulation is separated. This circumstance is of great importance, as it contributes to the maintenance of normal operation on grinders using the hot liquid defibration method.

The diagram of the thickener device is shown in fig. one.

Bath. Thickener baths are usually cast iron, sometimes concrete. In old factories, thickeners with wooden baths are found. On the end walls of the bath there is a device in the form of pegs or valves for regulating the level of outgoing circulating water.

Cylinder. The frame of the cylinder is formed from a series of rings resting on slats supported by spokes. A number of cast-iron crosses are mounted on a steel shaft. Chamfers are milled on the circumference of the rings, into which brass rods are installed on the edge along the entire generatrix of the cylinder, forming the cylinder frame. Sometimes brass rods are replaced with wooden ones, but the latter wear out quickly and are impractical.

As the experience of our enterprises shows, bars can be successfully replaced by sheets of perforated stainless steel 4 mm thick with their fastening to specially installed support rims.

A lower brass mesh, called lining, is put on the surface of the cylinder, and on top of it - the upper mesh No. 65-70. Nets consist of warp threads (running along the fabric) and weft threads (going across the fabric).

These cells of the nets, as well as the openings of the sieves, constitute their living section. Sometimes a middle grid No. 25-30 is placed between the upper and lower grids. Special rims are provided at the ends of the cylinder, and on the end walls of the bath there are protrusions corresponding to them, which serve to put on bandages (one for each end of the cylinder). Steel bandages with cloth pads are tightened with bolts, their purpose is to prevent the mass from seeping into the circulating water through the gaps between the cylinder and the bath.

Rice. 1. Scheme of the thickener device: 1 - wooden box; 2 - cast iron bath; 3 - mesh rotating drum; 4 - drive (idle and working) pulleys; 5 - drive gears; 6- receiving (pressure) roller; 7 - inclined plane; 8 - scraper; 9 - mixed pool of condensed mass

Receiving roller. The receiving roller is made of wood or cast iron. The surface of the roller is wrapped with woolen cloth in several turns (layers), and the cloth should be 150-180 mm wider than the length of the roller so that it can be pulled and fixed. Usually used - old cloth from the press rolls of paper machines.

The roller rotates in bearings mounted on levers. A special lifting mechanism, consisting of two flywheels (one at each end of the cylinder), spindles and springs, regulates the degree of pressing the roller against the drum, as well as raising and lowering it.

In thickeners of a later design, the take-up roller is made of metal with a soft rubber lining, and therefore there is no need to wrap it with a cloth.

Scraper. The scraper of the receiving shaft with an adjustable clamp is usually made of wood (from oak wood); he cleans the condensed mass from the roller, which then falls into the mixing pool. Outside the cylinder, in its entire width, there is a shryska pipe with a diameter of 50-60 mm, which serves to wash the mesh from fine fibers.

Cover box. The inlet (pressure) box in front of the bath serves to evenly distribute the mass over the entire width of the cylinder; usually it is made in the form of a funnel. The mass is brought to the box from below and, rising up, gradually "calms down", evenly distributed over the width of the cylinder. Sometimes, to calm the mass, a perforated distribution board with holes 60-70 mm in diameter is installed in the upper part of the box.

It is very important that the liquid mass entering the bath does not fall on the fiber layer deposited on the drum mesh, as in this case it will wash it off, which will significantly reduce the efficiency of the thickener. Therefore, often over the entire width of the cylinder, at a distance of 60-70 mm from its surface, a metal shield bent into a semicircle is installed on top, which protects the cylinder from falling on it of an uncondensed mass.

Some designs of thickeners do not have an overflow box. The mass is fed directly into the lower part of the bath under the switchboard (steel sheet covering the inlet at an angle). Hitting the shield, the mass is evenly distributed over the entire surface of the cylinder.

Due to the difference in the levels of the liquid entering the thickening outside the cylinder and the outgoing circulating water inside the cylinder, the mass is sucked to the rotating cylinder. At the same time, most of the water is filtered through the mesh cells, and the thickened fiber is deposited in an even layer across the entire width of the cylinder, additionally squeezed out by a receiving roller, removed with a scraper, and enters the mixing pool. A small part of the fiber does not pass between the cylinder and the receiving roller, is squeezed out by the latter to the edges of the cylinder and is directed along special water channels along with the entire thickened mass into the mixing pool. The concentration of the mass coming from the gutters is much lower and is usually 1.5-2.5%.

The specific thickening area and thickener productivity are taken according to the data obtained during the thickening of a similar product. If there are no such data, then the sedimentation rate of the solid phase of the pulp is preliminarily determined.

When thickening ore products, thickeners are usually calculated from the condition that grains no larger than 3–5 microns are lost in the drain. With the thickening of coal sludge, this limit rises to 30 - 40 microns.

The specific area of ​​thickener deposition per 1 ton of solid hourly output is calculated by formula (5.1):

where R and and R k - liquefaction in the initial and in the final (condensed) product; To is the utilization factor of the thickener area ( To= 0.6÷0.8); ν is the settling rate.

The total required thickening area is determined by the formula (5.2):

F=Q ∙ f or (5.2)

where F- total required thickening area, m 2; Q– hourly capacity of the thickener in terms of solids, t/h; g - specific productivity during the thickening of various concentrates, t / (m 2 ∙ h).

Thickener diameter D by expression (5.3):

(5.3)

According to the technical characteristics of the thickeners, the brand and type of the thickener are found. The selected thickener is checked according to the condition - the particle fall rate must be greater than the drain rate ( v o > v sl).

The settling rate for fine particles is calculated using the Stokes formula (5.4):

, (5.4)

where g- free fall acceleration, 9.81 m / s 2; d- particle size, m (particle diameter, the size of which is allowed as losses during discharge (3-5 microns); δ and ∆ are the density of the solid and liquid phases; μ – coefficient of dynamic viscosity, 0.001 n∙s.

The drain rate is determined from expression (5.5):

(5.5)

where ν s is the discharge speed, m/s; W c - the amount of discharge according to the water-slurry scheme, m 3 / day; F c is the area of ​​the selected thickener, m2.

If the conditions are not met, it is necessary to increase the area or use flocculants, or it is necessary to choose a thickener with a larger diameter.

test questions

1. What types of thickeners do you know?

2. What is the difference between center and peripheral drive thickeners?

3. Device and operation of thickeners with peripheral drive.

4.Advantages of thickener with sludge thickener.

5. Device and operation of lamellar thickeners.

6. Advantages of plate thickeners.

7. What provides a buried feed inlet thickeners with a suspended bed.

8.Stokes formula and its application.

10. Under what conditions is the selected thickener checked?

Man is constantly concerned with how to make life easier for himself. Take a look around you, think about what items in everyday life you would not have done without. Everyone will have their own long list. But it’s safe to say that there is a place on the list for both toilet paper and disposable napkins. In Russia, toilet paper began to be produced only in 1968, and before that they did not know about its existence and did very well without it.

What are toilet paper and disposable tissues made of?

Paper for the manufacture of disposable napkins and paper is made using special technologies. Cellulose and waste paper are raw materials for their production. They can be used separately or mixed. A special paper mass is made from the prepared raw materials, and toilet paper and disposable napkins are already made from it.

Lad-M offers all the necessary equipment:

YTS Series Cylindrical Screen

DRUM (HORIZONTAL) HYDRAULIC PUPPER

VERTICAL PRESSURE SCREENING

VERTICAL LOW CONCENTRATION HYDRAULIC PUPPER

VERTICAL PERMANENT HYDRAULIC PUPPER OF MIDDLE CONCENTRATION

VERTICAL LOW CONCENTRATION CONTINUOUS HYDRAULIC PUPPER

VIBRATION SORTING

VORTEX CLEANER FOR EASY INCLUSIONS

HIGH CONCENTRATION HYDRAULIC PULLER ZGS

SCRAPER

In the production of any paper, paper pulp is considered to be an aqueous suspension containing the necessary substances for making paper.

The production process of paper and napkins takes place in several stages:

• It all starts with the preparation of the mass itself - this is the first stage;
• The second stage is the manufacture of paper products from it.

Paper pulp can not be made from any waste paper. Only certain types are suitable, namely: white cellulose paper, lined paper, also white with black or colored stripes, book, magazine and archival paper (without covers, staples, bindings). You can also use cardboard, magazines, newspapers. The content of unsuitable paper in waste paper will lead to a decrease in the quality of the manufactured goods.

The following types of paper cannot be used to make paper pulp:

• covered with polyethylene, varnish, films, cloth;
• impregnated with various substances;
• burnt paper and cardboard;
• containing other materials: fabrics, ropes, wood, polyethylene;
• located in medical and veterinary institutions.

After collecting the necessary waste paper, special equipment for the preparation of paper pulp dissolves the raw material from waste paper or pulp into small fibers to a homogeneous mass, and is also cleaned of various impurities.

Further, with the help of special equipment, the raw material goes through several stages of cleaning and grinding, diluted with water to the desired consistency. After going through all the procedures, we get paper pulp ready for the manufacture of toilet paper and disposable napkins. Thus, the quality of the mass depends on the quality of raw materials, and the quality of the manufactured goods, in turn, depends on it.

Berezniki Polytechnic College
technology of inorganic substances
course project on the discipline "Processes and apparatuses of chemical technology
on the topic: "Selection and calculation of a slurry thickener
Berezniki 2014

Technical specifications
Nominal diameter of the tub, m 9
Depth of the tub, m 3
Nominal precipitation area, m 60
Rowing device lifting height, mm 400
Duration of one revolution of strokes, min 5
Conditional capacity for solids at density
condensed product 60-70% and specific gravity of solid 2.5 t/m,
90 t/day
Drive unit
electric motor
Type 4AM112MA6UZ
Number of revolutions, rpm 960
Power, kW 3
V-belt transmission
Belt type A-1400T
Gear ratio 2
Reducer
Type Ts2U 200 40 12kg
Gear ratio 40
Gear ratio of rotation mechanism 46
Total gear ratio 4800
lifting mechanism
electric motor
Type 4AM112MA6UZ
Number of revolutions, rpm 960
Power, kW 2.2
V-belt transmission
Belt type A-1600T
Gear ratio 2.37
Worm gear ratio 40
Total gear ratio 94.8
load capacity
Rated, t 6
Maximum, t 15
Rise time, min 4

Compound: Assembly drawing (SB), Rotation mechanism, PZ

Soft: KOMPAS-3D 14