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NSSC PULP MILL , 250 TPD

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REF.	49175-W2
BRAND	Sunds
Type	NSSC PULP MILL
Capacity ( TPD )	250 TPD TPD
YEAR	Before 1980
QUANTITY
LOCATION	EUROPE Western and Northern
DATE	28 Jul. 2008

NSSC PULP MILL , 250 TPD

NSSC Pulp Mill

Manufacturer: Sunds/Anthon B Nilsen

Type: NSSC Pulp

Size: 250 tpd based on raw material being beech. Digesting section will do 33 % more using birch

Material: All wetted parts in acid proof steel

Year made: Line 1: 1961, Line 2: 1967. Continuously renewed until 1997

Description: The pulping industries have shown an increasing interest in pulps of higher yields. The main interest has focused on semi-chemical and semi-mechanical pulps, but also on the processes for the bisulphite and kraft pulps.

Defibrator NSSC-Pulping
This method is different from most other pulping systems in that the actual pulping is carried out in vapour phase proceeded by liquor phase impregnation.

The chips are first subjected to normal steaming at atmospheric pressure. They are thereafter fed by a conically formed screw feeder into the bottom of the impregnation vessel which operates at atmospheric pressure and which is filled with the impregnation liquor. The chips are fed up through this vessel by means of a screw situated at the bottom. The impregnation liquor is kept at a temperature below 100 degrees C at the bottom of the vessel.

From the top of the impregnation vessel the chips are transported into two vapour phase digesters. There they are subjected to gas phase cooking at 160-170 degrees C for 60 minutes. Heating is by direct steam.

The digester is a vertical, cylindrical vessel of stainless steel with a slight taper downwards to prevent hang-ups. At the bottom an agitator conveys the chips down into the twin-screw that meters the chips to the internal feeding screw of an Asplund pressure fiberizing unit (L-36"). The speed of the twin screw is set to give the desired rate of production. A radiation level gage similar to the one on the steaming vessel ensures the desired cooking time at the given through-put. The gage actuates the variable speed drive of the feeding screw to the impregnator, thereby controlling the chip level in the digester. The impregnator operates permanently filled with chips. The Asplund pressurized disc defibrator operates at full digester pressure and is integrated with the digester.

The disintegrated pulp is discharged by a valve to a pressure cyclone for steam recovery, and the non-condensibles are vented to a water washed scrubber and odor-cleaned in two wash stations (NaOH and NaCl).

Thereafter the pulp is diluted to 12 % and fed into two DKP presses in parallel for extraction of the spent liquor. During this operation the fibres are not exposed to any kneeding or rolling action which could result in noodles or knots of fibres. The pulp may be dewatered to 50 % dryness.

The pulp is then diluted to 4 % consistency as it leaves the press and is washed a second time after which it passes through two Sund DWA 719 presses giving 30 % consistency. It is then diluted to 10 % and fed into the chest bin.

From this stage the pulp is split into two separate lines. It is treated in single disc refiners (Sund RGP-36) to a freeness of CFS 650-450. Several stages of screening and centricleaning follow before final thickening and drying. Mechanical dewatering is carried out on a Kamyr wet lap and on a Sunds defibrator twin-roll dewatering press (VPE 275), producing pulp of 40-50 % solids content. Shredding and defiberization is then carried out in a high-density disc fluffer, and the fibres are finally flash-dried in a two-stage system from Anthon B. Nielsen to 86-88 % solids content. The dryness of the pulp can be varied by adjusting the temperature of the drying gases leaving each drying stage from the top of the cyclones. Each stage is equipped with a control that records the temperature of the exit gases and keeps this temperature constant by varying the temperature of the entering gas.

The dry fluff pulp from the cooling stage cyclone is fed into the feed chute of the bale press. Pulp is compressed into slabs before baling in 200 kg bales. These bales are then tied with a strapping in an automatic tying machine and are then conveyed from the weighing station to the bale stacker. Due to its flexibility and low manpower requirements the flash dryer is well suited for drying marginal quantities of pulp.

THE PROCESS:
1. Chips are fed into a steaming vessel, then on to one impregnation vessel and from there into two NSSC digesters, one of 150 tpd (1) and one for 100 tpd (2).
2. After digesters there are two in-line refiners Sund Defibrator and then via a cyclone into two Sund Defibrator DKP presses. From there to pulp chest.
3. The gases from the cyclone are first cleaned in salt water washed scrubber; two wash stations: one with NaOH and one with NaOCl.
4. Cooking liquor is pumped into a special biological treatment not included in the sale.
5. If the pulp needs better washing there is a second stage washing stage with two Sund Defibrator DWA-719 twin-roll presses.
6. After the pulp chest the production is split up into two separate lines:
A: one line for 150 tpd with
- 4 refiners Sund Defibrator RGP 36 in parallel
- 2 selectifier screensv
- reject to Hedemora drum thickeners and 1 reject refiner Sunds Defibrator RGP 36
- accept to cleaners from Richard Berg and Albia
- dewatering in two Sund Defibrator drum thickeners, one UVA 2040 and one UVA 2550
B: one line for 100 tpd with
- refiners Sund Defibrator RGP 36
- screening in a Nima pressure screen
- reject to treatment in line one
- accept to cleaners Celleco and Noss
- dewatering in three Sund Defibrator drum thickeners, UVA 2040
7. After the pulping lines there are two dewatering presses: For line A: one Sund Defibrator VPE 275 For line B: one Kamyr wet lap machine
8. Pulp goes then to two separate flash dryers made by Anton B. Nilsen, the first with capacity of 150 tpd and the second of 100 tpd but easily increased to 150 tpd. The exhaust from the flash dryers is cleaned in two new scrubbers and dust bag filters.
PLEASE NOTE ITEM 8 IS NOT INCLUDED IN DELIVERY.
9. The dried pulp (87-90 %) is fed into a common hydraulic bale press. Final pressing for further comprimation is done in an ordinary bale press followed by weighing, strapping and unitising.
10. For sale is also a 70 m3/h chip screening system with disc screen from Winberg, a Liwell screen and a rechipper. Three is a large stock of spare parts.

SUMMARY OF EQUIPMENT:
1 x Steaming tower, D 1199/900 x 14865, 1961.
1 x Impregnation unit (atmospheric) with 12" ADI prex, 1961, D 1170 mm (bottom), 1800 mm (top), 13775 mm high.
1 x Digester 1: 29 m3, 12 bar, solid acid proof, 1967.
1 x Digester 2: 15 m3, 12 bar, solid acid proof, 1961.
2 x Defibrators, Sunds type L, D 800 mm grinding segm. 1961.
10 x Refiners Sunds RGP 36", D 900 mm grinding segm. 1961 + 1967 1 x Pulp cyclone, D 1600/1350, 1961.
2 x Presses, Sunds DKP, D 2.5 screen plates, 1961.
2 x Presses, Sunds DWA 719, 1990.
1 x Press, Sunds VPE 275, 1986, with
4x MA-200 hydraulic motors from 1992.
1 x Press, Rauma E20-44, D 900x600 cylinders, 1988, for waste paper, 60 tpd.
1 x Thickener, Hedemora, D 2500 x 5000.
4 x Thickeners, Sunds UVA 2040, D 2000 x 4000.
1 x Thickener, Sunds UVA 2550S, D 2550 x 5000.
1 x Press, Davenport.
1 x Pulp Dryer, Kamyr, D 700 x 3040, wire D 3000 x 3040, acid proof cylinders, with Nash CL 2002 pump, 1967.
1 x 5 stage Cleaner Package CCL, 1990, Albia / Richard Berg, 160 tpd.
1 x Cleaner system, Noss Radiclone P40, 1967.
1 x CCL-installation, Celleco, 1967.
1 x Selectifier, Black Clawson, 24" miami
1 x Pressure screen, Nima, D 900.
1 x Flash press, AB Nilsen type U, 250 tpd, 1972.
1 x Packing press, AB Nilsen 900 UL, 1972.
1 x Flash dryer, AB Nilsen, 150 tpd, steam heated with 13 and 3 bar, 1972, 1986, 1996 (not included in the delivery)
1 x Flash dryer, AB Nilsen, 110 tpd, steam heated with 13 and 3 bar, 1967, 1986, 1996 (not included in the delivery).
1 x Disc chip screen, Winberg WFSS-10, 1989, almost unused.
1 x Chip screen, Liwell LL1.0-3.78/12ED, 1989, almost unused.
1 x Rechipper, Winberg, WFK 12150/1250 H, 1990, almost unused.
1 x Pressure cyclone, Sunds, TCJ-1400, 1997.

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