Energy Saving Effect by Air Dryer Blow Nozzle Upgrade at PMN6 in Ishinomaki Mill

Abstract

Ishinomaki Mill is one of the main mills of Nippon Paper Industries. Its annual production amounts to 860,000 tons of paper from its 6 paper machines and 2 off-machine coaters. A pulverized coal boiler provides the main source of energy, with 2 black liquor recovery boilers and a biomass boiler also contributing to the energy supply.
We started operating the N6 paper machine (with on-machine coater) to reinforce our capacity in November 2007. The N6 paper machine is one of the largest capacity machines (1,005 tons per day) in Japan, and makes light-weight coated paper and A3 coated paper.
The speed of this paper machine is restricted by its drying capacity. A further problem is sheet breaks caused by lumps of dried coating color piling up in the air floating dryer. We installed a new blow nozzle in the air floating dryer in September 2014 to enhance drying capacity, and to avoid the lump pile-up by stabilizing web conveyance. As a result, we achieved a 20% energy saving through enhanced drying efficiency. However, it did not prevent lump pile-up enough. In this report I explain equipment details of air-dryer blow nozzle and operating experience with saving energy effect and dealing with sheet running.