“This boiler at OKI gives us economies of scale because of its size – basically if gives us much more efficiency at a lower cost.”
General Manager, OKI
APP’s OKI mill has seemingly sprung up from out of nowhere to become what is now one of the world’s largest pulp mills and is a real force with which to be reckoned in the global pulp and paper industry. It is a hugely ambitious and impressive development near Palembang, the provincial capital.
Dominating the whole mill complex and visible along the skyline for some miles before arriving at OKI is the jewel in the crown at the mill – the ANDRITZ supplied HERB Recovery Boiler, which is the world’s largest by some measure. The design capacity of the boiler is about 50% more than any other recovery boiler operating around the world today with a total capacity of 12,000 tons of black liquor dry solids per day (tds/d). To give an idea of the daily recovery boiler output at OKI, the unit could easily supply power to a European city of one million inhabitants with an output of 10,000 – 12,000 MWh per day. Ordinarily, two recovery boilers would have been needed for a mill with such a large capacity, which would have led to higher capital expense.
The boiler also has the world’s top steam data – 515°C at 110 bar as well as the latest technologies and features for maximizing power to heat ratios, allowing the mill to maximize green power generation.
So why go for such an ambitious target? David Kerr, General Manager at OKI, explains, “The newer recovery boilers being designed nowadays are extremely reliable and have many interlocks and permissives that guarantee safe operation. In addition, this boiler at OKI gives us economies of scale because of its size – basically it gives us much more efficiency at a lower cost. We went for the HERB technology because ANDRITZ has a proven track record with its recovery boilers and it has been shown that they get excellent performance and energy-saving results.”
General Manager, OKI
Kerr says of the start-up, “The OKI mill was started up in two phases; the recovery boiler came online with the first fiberline and as we tuned and brought it up to speed the recovery boiler followed very closely. Then shortly after we started the second fiberline and we ramped up the recovery boiler to near full capacity. It actually all went very smoothly.”
ANDRITZ also supplied major components and technology for the nine complete chipping lines installed in the woodyard at the OKI mill. The scope of supply included equipment for nine debarking lines including horizontally fed XL size HHQ-Chippers with feeding and discharge systems, wood breakage recovery systems, and log receiving decks with unique sand and stone separation features.
ANDRITZ also supplied 10 special bark crushers that ensure good particle size for the boiler operation specifically designed for acacia bark, which is stringy and can be difficult to handle.
Start-up Manager, ANDRITZ