Calculation of a disk thickener for the production of paper pulp. Disc pulp thickener PSN. General technological scheme of waste paper recycling

Calculation of fresh semi-finished products

As an example, the stock preparation department of a newsprint mill was calculated according to the composition specified in the water and fiber balance calculation, i.e. semi-bleached sulphate pulp 10%, thermomechanical pulp 50%, ground wood pulp 40%.

The consumption of air-dry fiber for the production of 1 ton of net paper is calculated based on the balance of water and fiber, i.e. the consumption of fresh fiber per 1 ton of newsprint net is 883.71 kg of absolutely dry (cellulose + DDM + TMM) or 1004.22 kg of air-dry fiber, including cellulose - 182.20 kg, DDM - 365.36 kg, TMM - 456.66 kg.

To ensure the maximum daily productivity of one paper machine, the consumption of semi-finished products is:

cellulose 0.1822 440.6 = 80.3 t;

DDM 0.3654 440.6 = 161.0 t;

TMM 0.4567 440.6 = 201.2 tons.

To ensure the daily net productivity of one paper machine, the consumption of semi-finished products is:

cellulose 0.1822 334.9 = 61 t;

DDM 0.3654 334.9 = 122.4 t;

ТММ 0.4567 334.9 = 153.0 t.

To ensure the annual productivity of the paper machine, the consumption of semi-finished products, respectively, is:

pulp 0.1822 115.5 = 21.0 thousand tons

DDM 0.3654 115.5 = 42.2 thousand tons;

ТММ 0.4567 115.5 = 52.7 thousand tons

To ensure the annual productivity of the factory, the consumption of semi-finished products is respectively:

pulp 0.1822 231 = 42.0 thousand tons

DDM 0.3654 231 = 84.4 thousand tons;

ТММ 0.4567 231 = 105.5 thousand tons.

In the absence of a calculation of the balance of water and fiber, the consumption of fresh air-dry semi-finished product for the production of 1 ton of paper is calculated by the formula: 1000 - V 1000 - V - 100 W - 0.75 K

RS = + P + OM, kg/t, 0.88

where B is the moisture contained in 1 ton of paper, kg; Z - ash content of paper,%; K - rosin consumption per 1 ton of paper, kg; P - irretrievable loss (wash) of 12% moisture fiber per 1 ton of paper, kg; 0.88 - conversion factor from absolutely dry to air-dry state; 0.75 - coefficient taking into account the retention of rosin in paper; RH - loss of rosin with recycled water, kg.

Calculation and selection of grinding equipment

The calculation of the number of grinding equipment is based on the maximum consumption of semi-finished products and taking into account the 24-hour duration of the equipment operation per day. In this example, the maximum consumption of air-dry pulp to be milled is 80.3 tons/day.

Method of calculation No. 1.

1) Calculation of disk mills of the first stage of grinding.

For pulp refining at high concentration according to the tables presented in“Equipment for pulp and paper production” (Handbook for students special. 260300 “Technology of chemical processing of wood” Part 1 / Comp. F.Kh. Khakimov; Perm. state technical university Perm, 2000. 44 p. .) mills of the MD-31 brand are accepted. Specific load on the knife edge Вs= 1.5 J/m. At the same time, the second cutting length Ls, m/s, is 208 m/s (Section 4).

Effective grinding power Ne, kW, is equal to:

N e = 103 Вs Ls j = 103 1.5 . 0.208 1 = 312 kW,

where j is the number of grinding surfaces (for a single-disk mill j = 1, for a double mill j = 2).

Mill performance MD-4Sh6 Qp, t/day, for the accepted grinding conditions will be:

Where qe=75 kWh/t specific useful energy consumption for refining sulphate unbleached pulp from 14 to 20 °SR (Fig. 3).

Then the required number of mills for installation will be equal to:

The productivity of the mill varies from 20 to 350 tons/day, we accept 150 tons/day.

We accept two mills for installation (one in reserve). Nxx = 175 kW (section 4).

Nn

Nn \u003d Ne + Nxx= 312 + 175 = 487 kW.

K Nn> Ne+Nxx;

0,9.630 > 312 + 175; 567 > 487,

2) Calculation of mills of the second stage of grinding.

For grinding cellulose at a concentration of 4.5%, mills of the MDS-31 brand are accepted. Specific load on the knife edge Вs\u003d 1.5 J / m. The second cutting length is taken according to Table. 15: Ls\u003d 208 m / s \u003d 0.208 km / s.

Effective grinding power Ne, kW, will be equal to:

Ne \u003d Bs Ls \u003d 103 1.5. 0.208 1 = 312 kW.

Specific electricity consumption qe, kWh/t, for pulp refining from 20 to 28°ShR according to the schedule will be (see Fig. 3);

qe = q28 - q20= 140 - 75 = 65 kWh/t.

Mill performance Qp, t/day, for the accepted working conditions will be equal to:

Then the required number of mills will be:

Nxx = 175 kW (section 4).

Power consumed by the mill Nn, kW, for the accepted grinding conditions will be equal to:

Nn \u003d Ne + Nxx= 312 + 175 = 487 kW.

Checking the power of the drive motor is carried out according to the equation:

K Nn> Ne+Nxx;

• 0,9.630 > 312 + 175;
• 567 > 487,

therefore, the motor test condition is fulfilled.

Two mills are accepted for installation (one in reserve).

Method of calculation No. 2.

It is expedient to calculate the grinding equipment according to the above calculation, however, in some cases (due to the lack of data on the selected mills), the calculation can be carried out according to the formulas below.

When calculating the number of mills, it is assumed that the grinding effect is approximately proportional to the energy consumption. Electricity consumption for pulp milling is calculated by the formula:

E=e Pc (b-a), kWh/day,

Where e? specific electricity consumption, kWh/day; PC? the amount of air-dry semi-finished product to be ground, t; A? the degree of grinding of the semi-finished product before grinding, oShR; b? the degree of grinding of the semi-finished product after grinding, oShR.

The total power of the electric motors of grinding mills is calculated by the formula:

Where h? load factor of electric motors (0.80?0.90); z? number of mill hours per day (24 hours).

The power of the electric motors of the mills according to the grinding stages is calculated as follows:

For the 1st grinding stage;

For the 2nd grinding stage,

Where X1 And X2? distribution of electricity to the 1st and 2nd stages of grinding, respectively, %.

The required number of mills for the 1st and 2nd grinding stages will be: technological paper machine pump

Where N1M And N2M? power of the electric motors of the mills to be installed at the 1st and 2nd grinding stages, kW.

In accordance with the accepted technological scheme, the grinding process is carried out at a concentration of 4% up to 32 oShR in disc mills in two stages. The initial degree of grinding of semi-bleached sulphate softwood pulp is accepted as 13 OSR.

According to practical data, the specific energy consumption for grinding 1 ton of bleached softwood sulphate pulp in conical mills will be 18 kWh/(t chr). The calculation assumes a specific energy consumption of 14 kWh/(t oShR); since the grinding is designed in disc mills, is the energy savings taken into account? 25%.

Total required for grinding electricity will be:

E \u003d 14 80.3 (32-13) \u003d 21359.8 kWh / day.

To ensure this power consumption, it is necessary that the total power of the electric motors installed for grinding mills is:

The power consumption of the grinding stages is distributed in accordance with the properties of the semi-finished product to be ground and the type finished products. In the example under consideration, the composition of paper includes 40% wood pulp and 50% thermomechanical pulp, so the nature of the grinding of sulfate softwood pulp should be without shortening the fiber with sufficient high degree its fibrillation. Based on this, it is advisable to provide 50% of the power for the 1st and 2nd stages of grinding softwood pulp. Therefore, at the 1st stage of grinding, the total power of the electric motors of the mills should be:

N1=N2=1047 0.5=523.5 kW .

The project provides for the installation of mills MD-31 with a power of 630 kW electric motors, which differ in the nature of the headset at the 1st and 2nd stages. The required number of mills for the 1st or 2nd stage of grinding will be:

Taking into account the reserve, it is necessary to provide 4 mills (there is a reserve mill at each stage).

Based on the productivity of the MD-31 mill (up to 350 t/day), the amount of fiber that needs to be passed through the mills (80.3 t/day), the amount of increase in the degree of grinding that should be provided (19 OSR), a conclusion was made about the installation mills in series.

According to the technological scheme, the mass preparation department provides for the installation of an MP-03 pulsation mill for the dissolution of recycled marriage.

The number of pulse mills is calculated using the following formula:

where QP.M. ? performance of the pulse mill, t/day;

A? the amount of absolutely dry fiber entering the pulse mill, kg / t.

The main parameters of the mills provided for installation are given in Table. 1

Table 1 - Main parameters of installed mills

Note. Overall dimensions of the MP-03 mill: 244.5×70.7×76.7 cm.

Calculation of the volume of pools

The calculation of the volume of pools is based on maximum number the mass to be stored and the required storage time of the mass in the pool. According to Giprobum's recommendations, pools should be designed for 6-8 hours of mass storage.

As a rule, the duration of storage of semi-finished products before and after grinding is accepted? 2 ... 4 hours, and paper pulp in the composite (mixing) and machine pool? 20?30 min. In some cases, it is planned to store semi-finished products before grinding in towers of high concentration (12 ... 15%), calculated for a 15 ... 24-hour supply. Stock time can be reduced by using modern systems automation.

The calculation of the volume of pools is made according to the formula:

The calculation of the volume of pools is also carried out according to the formula (if there is a calculation of the balance of water and fiber):

where QN.BR. ? hourly productivity of PM (KDM), t/h; QM? the amount of fibrous suspension in the pool, m3/t of paper; t- mass storage time, h; TO- coefficient taking into account the incomplete filling of the pool (usually TO =1,2).

The time for which the mass reserve is calculated in a pool of a certain volume is calculated by the formula:

Where P V? pool volume, m3; With? humidity of air-dry fibrous material, % (in accordance with GOST for semi-finished products With= 12%, for paper and cardboard With = 5?8 %); t? mass storage time; z c? concentration of fibrous suspension in the pool, %; k? coefficient taking into account the incompleteness of the pool (usually k = 1,2).

The volumes of the pools provided for in the considered technological scheme are calculated as follows (for one machine):

Pulp receiving basin

For example, let's take a calculation using the second formula:

receiving pool for DDM

receiving basin for TMP

pulp pool

intermediate basin for DDM

intermediate basin for TMP

composite pool

machine pool

The volume of pools for reverse marriage is calculated in case of emergency operation of the machine (50 or 80% of QSUT.BR).

The volume of the wet marriage pool:

The volume of the pool for dry marriage:

The volume of pools for recycled scrap is calculated for a total storage capacity of 4 hours. If a pool for recycled scrap from pulpers is provided in the machine room, the duration of storage of dissolved recycled scrap in the pools installed in the mass preparation department can be reduced.

The volume of the pool for reverse marriage:

For water collectors, we accept the storage time: for a collector of under-grid water, 5 minutes, i.e. 5: 60 = 0.08 h; for the collection of recycled water 15 min; for excess circulating water collector 30 min.

Undergrid water collector

Collector of recycled water

Collection of excess recycled water

Clarified water collection

The volumes of pools must be unified in order to facilitate their manufacture, layout, operation and repair. It is desirable to have no more than two sizes. The results of unification should be presented in the form of a table. 2

Table 2 - Results of unification of basins

For the factory, the number of pools obtained is doubled.

1) Kaolin slurry collector

2) Collector for dye solution

3) Collector for PAA solution

4) Collector for alumina solution

Calculation and selection of mass pumps

The choice of the pump is made on the basis of the total pressure of the mass, which the pump must create, and its performance. Calculation of the total head of the pump should be carried out after the layout drawings have been completed and the exact location of the pump has been determined. In this case, it is necessary to draw up a pipeline diagram indicating their length and all local resistances (tee, transition, branch, etc.). The principle of calculating the required pressure, which the pump must create, and the value of the local resistance coefficients are given in the special literature. Typically, to move fibrous suspensions within the mass preparation department, the pump must provide a head of 15–25 m.

Pump performance is calculated by the formula:

Where P? the amount of air-dry fibrous material, t/day; With? humidity of air-dry fibrous material, %; z? number of working hours per day (24 hours); c/? concentration of fibrous suspension in the pool, %; 1.3? coefficient taking into account the pump performance margin.

The volumetric flow rate of the liquid pumped by the pump at a concentration of 1 ... 4.5 can also be determined from the calculation of the balance of water and fiber.

Qm=M. pH 1.3,

Where pH- hourly productivity of the paper machine, t/h;

M- mass of pumped fibrous suspension (from the balance of water and fiber), m3.

Pump calculation

Mass pumps

1) Pump feeding pulp to disc mills

Qm=M. pH 1.3 = 5.012 18.36 1.3 = 120 m3/h.

We accept for installation the BM 125/20 pump following characteristic: feed? 125 m3/h; pressure? 20 m; limiting concentration of the final mass? 6%; power? 11 kW; rotation frequency? 980 rpm; efficiency ? 66%. A reserve is provided.

2) Pump supplying DDM from the receiving pool to the intermediate

Qm=M. pH 1.3 \u003d 8.69 18.36 1.3 \u003d 207 m3 / h.

3) Pump supplying TMP from the receiving pool to the intermediate

Qm=M. pH 1.3 \u003d 10.86 18.36 1.3 \u003d 259 m3 / h.

4) Pump supplying pulp from the ground pulp pool to the composite one

Qm=M. pH 1.3 \u003d 2.68 18.36 1.3 \u003d 64 m3 / h.

5) Pump supplying DDM from the intermediate basin to the composite one

Qm=M. pH 1.3 = 8.97 18.36 1.3 = 214 m3/h.

We accept for installation the BM 236/28 pump with the following characteristic: supply? 236 m3/h; pressure? 28 m; limiting concentration of the final mass? 7%; power? 28 kW; rotation frequency? 980 rpm; efficiency ? 68%. A reserve is provided.

6) Pump supplying TMP from the intermediate pool to the composite one

Qm=M. pH 1.3 \u003d 11.48 18.36 1.3 \u003d 274 m3 / h.

We accept for installation the BM 315/15 pump with the following characteristic: supply? 315 m3/h; pressure? 15 m; limiting concentration of the final mass? 8 %; power? 19.5 kW; rotation frequency? 980 rpm; efficiency ? 70%. A reserve is provided.

7) Pump supplying paper pulp from the composite pool to the machine

Qm=M. pH 1.3 = 29.56 18.36 1.3 = 705 m3/h.

8) Pump supplying paper pulp from the machine pool to the MCR

Qm=M. pH 1.3 = 32.84 18.36 1.3 = 784 m3/h.

We accept for installation the BM 800/50 pump with the following characteristic: supply? 800 m3/h; pressure? 50 m; limiting concentration of the final mass? 8 %; power? 159 kW; rotation frequency? 1450 rpm; efficiency ? 72%. A reserve is provided.

9) Pump supplying paper pulp from the dry reject pool to the recycled reject pool

Qm=M. pH 1.3 = 1.89 18.36 1.3 = 45 m3/h.

We accept for installation the pump BM 67 / 22.4 with the following characteristic: supply? 67 m3/h; pressure? 22.5 m; limiting concentration of the final mass? 4 %; power? 7 kW; rotation frequency? 1450 rpm; efficiency ? 62%. A reserve is provided.

10) Pump supplying paper pulp from the wet reject pool to the recycled reject pool

Qm=M. pH 1.3 \u003d 0.553 18.36 1.3 \u003d 214 m3 / h.

We accept for installation the BM 236/28 pump with the following characteristic: supply? 236 m3/h; pressure? 28 m; limiting concentration of the final mass? 7%; power? 28 kW; rotation frequency? 980 rpm; efficiency ? 68%. A reserve is provided.

11) Pump supplying paper stock from the recycled waste pool to the composite one

Qm=M. pH 1.3 \u003d 6.17 18.36 1.3 \u003d 147 m3 / h.

We accept for installation the BM 190/45 pump with the following characteristic: supply? 190 m3/h; pressure? 45 m; limiting concentration of the final mass? 6%; power? 37 kW; rotation frequency? 1450 rpm; efficiency ? 66%. A reserve is provided.

12) Pump that feeds ground pulp through the sublayer

Qm=M. pH 1.3=2.5 18.36 1.3 = 60 m3/h.

We accept for installation the pump BM 67 / 22.4 with the following characteristic: supply? 67 m3/h; pressure? 22.5 m; limiting concentration of the final mass? 4 %; power? 7 kW; rotation frequency? 1450 rpm; efficiency ? 62%. A reserve is provided.

13) A pump that delivers marriage from a couch mixer

Qm=M. pH 1.3 = 2.66 18.36 1.3 = 64 m3/h.

We accept for installation the pump BM 67 / 22.4 with the following characteristic: supply? 67 m3/h; pressure? 22.5 m; limiting concentration of the final mass? 4 %; power? 7 kW; rotation frequency? 1450 rpm; efficiency ? 62%.

14) Pump supplying marriage from the couch mixer (with emergency work cars)

We accept for installation the BM 315/15 pump with the following characteristic: supply? 315 m3/h; pressure? 15 m; limiting concentration of the final mass? 8 %; power? 19.5 kW; rotation frequency? 980 rpm; efficiency ? 70%. A reserve is provided.

15) The pump that feeds the waste from the pulper under the freewheel(In the calculation, pulpers No. 1 and 2 are combined, therefore, we calculate the approximate mass attributable to this pulper 18.6 kg a.d.w. x 2 = 37.2 kg, 37.2 x 100/3 = 1240 kg = 1.24 m3)

Qm=M. pH 1.3 = 1.24 18.36 1.3 = 30 m3 / h.

16) Pump supplying scrap from the pulper under the freewheel (in case of emergency operation of the machine)

We accept for installation the BM 475/31.5 pump with the following characteristic: supply? 475 m3/h; pressure? 31.5 m; limiting concentration of the final mass? 8 %; power? 61.5 kW; rotation frequency? 1450 rpm; efficiency ? 70%. A reserve is provided.

17) Pump supplying marriage from the pulper (under the PRS)(In the calculation, pulpers No. 1 and 2 are combined, therefore, we calculate the approximate mass per this pulper 18.6 kg (a.d.w.) x 100/3 = 620 kg = 0.62 m3)

Qm=M. pH 1.3 = 0.62 18.36 1.3 = 15 m3/h.

We accept for installation the BM 40/16 pump with the following characteristic: supply? 40 m3/h; pressure? 16 m; limiting concentration of the final mass? 4 %; power? 3 kW; rotation frequency? 1450 rpm; efficiency ? 60%.

Mixing pumps

1) Mixing pump #1

Qm=M. pH 1.3 \u003d 332.32 18.36 1.3 \u003d 7932 m3 / h.

We accept for installation the pump BS 8000/22 with the following characteristic: supply? 8000 m3/h; pressure? 22 m; power? 590 kW; rotation frequency? 485 rpm; efficiency ? 83%; weight? 1400.

2) Mixing pump #2

Qm=M. pH 1.3 \u003d 74.34 18.36 1.3 \u003d 1774 m3 / h.

We accept for installation the pump BS 2000/22 with the following characteristic: supply? 2000 m3/h; pressure? 22 m; power? 160 kW; rotation frequency? 980 rpm; efficiency ? 78%.

3) Mixing pump #3

Qm=M. pH 1.3 = 7.6 18.36 1.3 = 181 m3/h.

We accept for installation the pump BS 200/31.5 with the following characteristic: supply? 200 m3/h; pressure? 31.5 m; power? 26 kW; rotation frequency? 1450 rpm; efficiency ? 68%.

Water pumps

1) A pump that supplies recycled water for diluting waste after sorting, rejects into a couch mixer, pulpers (about 8.5 m3 according to the balance). A reserve is provided.

Qm=M. pH 1.3=8.5 18.36 1.3 = 203 m3/h.

We accept for installation the pump K 290/30 with the following characteristic: supply? 290 m3/h; pressure? 30 m; power? 28 kW; rotation frequency? 2900 rpm; efficiency ? 82%.

2) Pump supplying clarified water to concentration regulators (according to balance, approximately 3.4 m3)

Qm=M. Рн 1.3=3.4 18.36 1.3 = 81 m3/h.

We accept for installation the pump K 90/35 with the following characteristic: supply? 90 m3/h; head 35 m; power? 11 kW; rotation frequency? 2900 rpm; efficiency ? 77%. A reserve is provided.

3) Fresh water supply pump (balance approx. 4.23 m3)

Qm=M. pH 1.3 \u003d 4.23 18.36 1.3 \u003d 101 m3 / h.

We accept for installation the pump K 160/30 with the following characteristic: supply? 160 m3/h; pressure? 30 m; power? 18 kW; rotation frequency? 1450 rpm; efficiency ? 78%. A reserve is provided.

4) The pump for supplying fresh filtered water to the showers of the screen table and the press section (according to the balance of about 18 m3)

Qm=M. pH 1.3=18 18.36 1.3 = 430 m3/h.

We accept for installation the pump D 500/65 with the following characteristic: supply? 500 m3/h; pressure? 65 m; power? 130 kW; rotation frequency? 1450 rpm; efficiency ? 76%. A reserve is provided.

5) Pump for supplying excess circulating water to the disc filter(according to the balance approximately 40.6 m3)

Qm=M. pH 1.3 \u003d 40.6 18.36 1.3 \u003d 969 m3 / h.

5) Pump for supplying excess clarified water for use(according to balance approximately 36.3 m3)

Qm=M. pH 1.3 = 36.3 18.36 1.3 = 866 m3/h.

We accept for installation the pump D 1000/40 with the following characteristic: supply? 1000 m3/h; pressure? 150 m; power? 150 kW; rotation frequency? 980 rpm; efficiency ? 87%. A reserve is provided.

Chemical pumps

1) Kaolin slurry pump

Qm=M. pH 1.3 = 0.227 18.36 1.3 = 5.4 m3/h.

2) Dye solution pump

Qm=M. pH 1.3 = 0.02 18.36 1.3 = 0.5 m3/h.

We accept for installation the pump X2 / 25 with the following characteristic: supply? 2 m3/h; pressure? 25 m; power? 1.1 kW; rotation frequency? 3000 rpm; efficiency ? 15 %. A reserve is provided.

3) PAA solution pump

Qm=M. pH 1.3=0.3 18.36 1.3 = 7.2 m3/h.

We accept for installation the pump X8 / 18 with the following characteristic: supply? 8 m3/h; pressure? 18 m; power? 1.3 kW; rotation frequency? 2900 rpm; efficiency ? 40%. A reserve is provided.

3) Alumina solution pump

Qm=M. pH 1.3 = 0.143 18.36 1.3 = 3.4 m3/h.

We accept for installation the pump X8 / 18 with the following characteristic: supply? 8 m3/h; pressure? 18 m; power? 1.3 kW; rotation frequency? 2900 rpm; efficiency ? 40%. A reserve is provided.

Recycling marriage

Calculation of the volume of the couch mixer

We accept the storage time in the couch-mixer in emergency mode 3 min; the mixer should be designed for 50…80% of the machine’s productivity (in this case, the concentration increases to 3.0…3.5%):

We accept for installation a couch-mixer with a volume of 16 ... 18 m3 of CJSC Petrozavdskmash with the following characteristics: with working bodies on a horizontal shaft, the number of propellers? 4 things.; propeller diameter? 840 mm; rotor speed? 290…300 min-1; electric motor power 75…90 kW.

Calculation of pulpers

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

334.9 0.8 = 268 t/day.

We choose the GRVm-32 pulper with the following characteristics: performance? 320 t/day; motor power? 315 kW; tub capacity? 32 m2; sieve hole diameter? 6; 12; 20; 24 mm.

For marriage from finishing (according to the balance 2% of the net output)

334.9 0.02 = 6.7 t/day.

We choose a pulper GDV-01 with the following characteristics: productivity? 20 t/day; motor power? 30 kW; rotor speed? 370 rpm; tub diameter? 2100 mm; rotor diameter? 2100 mm.

marriage thickener

To thicken wet recycled waste, we use the SG-07 thickener with the following characteristics:

Sorting and cleaning equipment

Calculation of knotters

Number of knotters n is determined by the formula:

Where RS.BR.- daily productivity of the paper machine, gross, t/day;

A- the amount of absolutely dry fiber supplied for cleaning, per ton of paper (taken from the calculation of water and fiber), kg / t;

Q- productivity of the knotter for air-dry fiber, t/day.

We accept for installation 3 screens (one in reserve) of the Ahlscreen H4 type with the following characteristics: performance? 500 t/day; motor power? 55 kW; rotor speed? 25 s-1; sealing water consumption? 0.03 l/s; sealing water pressure? 10% higher than mass inlet pressure; maximum inlet pressure? 0.07 MPa.

Vibration sorting calculation

We accept for installation 1 vibration sorting type SV-02 with the following characteristic: productivity? 40 t/day; motor power? 3 kW; sieve hole diameter? 1.6...2.3 mm; sieve oscillation frequency? 1430 min-1; length? 2.28 m; width? 2.08 m; height? 1.06 m

Calculation of cleaners

Vortex cleaner installations are assembled from a large number of individual tubes connected in parallel. The number of tubes depends on the capacity of the plant:

Where Q- installation productivity, dm3/min;

Qt- productivity of one tube, dm3/min.

The productivity of the installation is determined according to the calculation of the material balance of water and fiber.

Where R- hourly productivity of the machine, kg/h;

M- mass of fibrous suspension supplied for treatment (from the balance of water and fiber), kg/t;

d is the density of the fibrous suspension (when the mass concentration is less than 1%, d = 1 kg/dm3), kg/dm3.

1st cleaning stage

dm3/min.= 1695 l/s.

We accept for installation 4 blocks of Ahlcleaner RB 77 cleaners, each block has 104 pcs. cleaners. Dimensions of the 1st block: length 4770 mm, height - 2825, width - 1640 mm.

2nd cleaning stage

dm3/min.= 380 l/s.

Calculate the number of purifier tubes if throughput one tube 4.2 l/s.

We accept for installation 1 block of Ahlcleaner RB 77 cleaners, the block includes 96 pcs. cleaners. Dimensions of the 1st block: length 4390 mm, height - 2735, width - 1500 mm.

3rd stage cleaning

dm3/min.= 39 l/s.

We calculate the number of purifier tubes if the throughput of one tube is 4.2 l / s.

We accept for installation 1 block of Ahlcleaner RB 77 cleaners, the block includes 10 pcs. cleaners. Dimensions of the 1st block: length 1980 mm, height - 1850, width - 860 mm.

The cleaning system is equipped with a deaeration tank with a diameter of 2.5 m and a length of 13 m. generated by a system consisting of a steam ejector, a condenser and a vacuum pump.

Disc filter

Disc filter performance Q, m 3 / min, is determined by the formula:

Q=F. q,

Where F- filtration area, m2;

q- capacity, m3/m2 min.

Then the required number of filters will be determined:

Where Vmin- the volume of excess water supplied for treatment, m3/min.

It is necessary to pass 40583 kg of recycled water or 40.583 m3 through the disc filter, let's determine the volume of excess water

40.583 18.36 = 745 m3/h=12.42 m3/min.

Q \u003d 0.04 434 \u003d 17.36 m 3 / min.

We accept for installation a Hedemora VDF disk filter, type 5.2 with the following characteristics: 14 disks, length 8130 mm, empty filter weight 30.9 t, working weight 83 t.

The "Papcel" scraperless thickener has a double-walled trough for mass inlet and a chute for removal of the condensed mass. From the sides, the bath is closed with cast-iron end walls. By turning a special segment, you can adjust the height of the level of water leaving the thickener. The structure of the mesh-covered cylinder consists of brass rods, to which the lower (lining) brass mesh No. 2 is attached. The fabric of the upper mesh is made of phosphor bronze; the number of the upper grid depends on the type of mass being condensed. The thickener is equipped with an individual drive mounted on the left or right side of the thickener. With a concentration of the incoming mass of 0.3-0.4%, it is possible to thicken the mass up to 4%. The diameter of the thickener drum "Papcel-23" is 850 mm, its length is 1250 mm, the capacity of the thickener is 5-8 tons per day. The larger type of such thickener, Papcel-18, has a drum with a diameter of 1250 mm and a length of 2000 mm and a capacity of 12-24 tons per day, depending on the type of mass.

Voith thickeners have a diameter of 1250 mm. The mass thickens to a concentration of 4-5% and even up to 6-8%. Data on the performance of Voith thickeners are given in Table. 99.

The Yulha thickener with a scraper roller (fig. 134) has a drum consisting of steel rods covered with lining mesh No. 5. A working filter mesh is stretched over this mesh. The diameter of the mesh cylinder is 1220 mm. Its rotation speed is 21 rpm. The nitrile rubber coated scraper roller has a diameter of 490 mm and is pressed

To the mesh cylinder with springs and screws. The scraper is made from micarta, a hard fibrous material. The seal between the bath and the open ends of the cylinder is

Made with nitrile rubber tape. All parts in contact with the ground are made of stainless steel or bronze. Technical indicators of Yulhya thickeners are given in Table. 100.

Thickener "Papcel" with a removable scraper roller can be used to thicken the mass from 0.3-0.4% to 6%. The design of the mesh drum is the same as that of the bladeless thickener of the same company. The drum diameter is 1250 mm, its length is 2000 mm. Pressure roller diameter 360 mm. The capacity of the thickener is 12-24 tons per day, depending on the mass.

For drum thickeners, the circumferential speed must not be allowed to exceed 35-40 m/min. The numbers of filter meshes are selected taking into account the properties of the thickened mass. For wood pulp, grids No. 24-26 are used. When choosing a mesh number, the rule that the thickener mesh for waste paper and recycled paper should be the same as the mesh of the paper machine should be observed. The service life of a new mesh is 2-6 months, the service life of an old mesh used after paper machines is 1 to 3 weeks. The performance of the thickener depends to a large extent on the mesh number and the condition of its surface. During operation, the mesh must be continuously flushed with water from the showers. For each running meter of a shower pipe with a hole diameter of 1 mm, 30-40 l / min of water should be consumed at a pressure of 15 m of water. Art. When using recycled water, the need for spray water doubles.

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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)

By technical specification thickeners find brand and type of thickener. The selected thickener is checked according to the condition - the particle fall rate must be more speed plum ( 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.

Control 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?

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 performed with a denser mass. Otherwise, pools of very large capacity would be required. That's why good mass after sorting, they are sent to thickeners, where it is thickened to a concentration of 5.5-7.5'. During the thickening of the mass, most of the warm water coming into circulation. This circumstance has great importance, as it helps to maintain the normal mode of operation on grinders using the hot liquid defibration method.

The diagram of the thickener device is shown in fig. 1.

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. On the circumference of the rings, chamfers are milled, into which brass rods are installed on the edge along the entire generatrix of the cylinder, forming the frame of the cylinder. Sometimes brass rods are replaced with wooden ones, but the latter wear out quickly and are impractical.

As the experience of our enterprises shows, the 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 with a diameter of 60-70 mm 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 take-up roller, it 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%.

Pulp thickener - a device that continuously affects the diluted pulp to concentrate it through partial dehydration. By design, these devices can be disk, inclined, tape and drum.

The belt thickener is one of the most popular types. Its design includes two mesh-covered drums, which go around an endless rubberized belt.

Our company "TsBP-Service" offers the following models of thickeners: ZNP disc filter, ZNW drum thickener, ZNX inclined thickener.

Compact and efficient device made of stainless steel.

It performs well in thickening and washing pulp from recycled paper.

Specifications of the ZNP disc filter

A device designed to work with low concentration fiber. It features simple structure and easy operation.

The enhanced dewatering function results in a thicker stock.

Specifications of ZNW Drum Thickener

The device is simple in structure and easy to maintain.

It produces a very high dewatering effect, which makes this model particularly in demand in the paper industry.

Specifications of ZNX Inclined Thickener

Paper pulp thickeners in St. Petersburg

You can buy paper pulp thickeners and other parts of a paper machine in our company "TsBP-Service".