International technology Group ANDRITZ has successfully completed the start-up of new production technologies and equipment for the extension of SCA’s Östrand pulp mill in Timrå, Sweden.
ANDRITZ supplied the following equipment for the SCA Östrand mill:
- a complete debarking plant with two parallel debarking and chipping lines each consisting of a PowerFeed de-icing conveyor, a hydrostatically supported debarking drum for a capacity of 425 m3 sob/h and measuring 5.5 x 39 meters, and a horizontally fed, XL-size HHQ-Chipper operating with a TK-IV knife system. The delivery also includes two new-generation HQ-Press bark presses resulting in excellent bark dry content, as well as modernization of the existing chip handling system;
- the new innovative EvoDry pulp drying system with its energy-saving technologies that substantially reduce the mill’s operating costs, including a boiler exhaust energy recovery system, fine screening, a twin wire dewatering system with a fully automatic tail threading system to meet strictest health, safety, and environmental regulations, a new-generation sheet dryer for lowest downtime and fast start up, as well as a cutter and two baling lines;
- new recausticizing machinery including a LimeGreen green liquor filter enabling efficient green liquor filtration with a minimum of waste going to landfill, two LimeFree centrifuges for dregs, LimeSlake technology, LimeWhite white liquor disc filter to optimize white liquor quality, and LimeDry lime mud disc filter upgrade;
- ANDRITZ LimeFlash technology, enabling a substantial increase in the capacity of the existing lime kiln without the need to invest in a new lime kiln. The delivery also included upgrade of the existing wood dust burning system, which ANDRITZ supplied in 2011 in order to support the new increased lime kiln capacity.
- substantial increase in the recovery boiler capacity from 3,300 to 5,000 tds/d. The existing boiler was supplied by ANDRITZ in 2006 and had already been designed to enable a major extension by moving the boiler side wall and widening the heating surfaces of the superheater, boiler generation bank, and economizers. The boiler extension by moving the side wall allows optimum flue gas flux before and after the rebuild, which has great benefits compared to traditional technology for expanding the recovery boiler by moving its front wall. The total increase of the boiler width was 3.8 meters. In addition to boiler enlargement, one additional ESP°(electrostatic precipitator) chamber and feed water pump were added.
The mill expansion was one of the largest industrial investments in Sweden and the largest ever in northern Sweden. SCA Östrand is doubling its annual production capacity from 430,000 to 900,000°tons, thereby becoming the largest mill in the world for softwood kraft pulp.