Paper360 - March/April 2015 - (Page 39)

millwise | TRALIN PAPER The World's First Fully Automated Continuous Digester for nonwood Pulp Production Nine invited experts agreed that Tralin Paper's startup was a major breakthrough in nonwood pulping technology which could greatly impact not only China but other parts of the world where forest resources are limited. HOU-MIN CHANG Shandong Tralin Paper Company of China invited nine experts to witness the October 2014 unveiling of novel upright continuous digesters for the production of 100 percent wheat straw pulp, at their mill in Gaotang, Shandong, China. The digesters are fully automated, from raw material preparation to blow tank. This is, without a doubt, a major breakthrough for the Chinese company, as previously the continuous digester, of a type similar to the Kamyr digester, was not regarded as feasible for straw pulping. The mill's innovation and persistent research efforts allowed them to develop the first fully automated continuous digester for nonwood pulp production in the world. There are three breakthrough innovations that distinguish the Tralin continuous digester from the Kamyr digester. The first innovation is the raw material preparation system. The mill prepares cleaned straw for pulping using a combination of a traditional straw cutting machine and Tralin-designed rotary drum hammer mill. The system is fully automated and allows the mill to raise the straw acceptance rate from 75 percent to 92 percent. The second innovation is the feeding system to the digester. Unlike with wood chips, highpressure feeders cannot be used for wheat straw because of the difficulty in separating the liquor and straw at the top separator. To overcome the problem, the mill designed a dual screw feeding system at the top of the digester. The third innovation is the screen system in the digester that allows liquor to be withdrawn from the digester for indirect heating and for delivery to the hot liquor tank. The withdrawal of liquor from the digester is relatively easy for wood chips but is typically not considered Professor Li, Zhongzheng (center) talks to the operator (in blue) in the Tralin control room. Standing behind him are (l-r) Mr. Yu, Xuejun; Mr. Chen, Sontao, a chief engineer of Tralin; Ms. Cao, Pufang; and Dr. Chen, Jiachuan (partially hidden behind Prof. Li). New fully automated digesters prove that continuous digesters are feasible for straw pulping. Mr. Hou-min Chang, professor emeritus at North Carolina State University (center), one of only nine experts (and the only one from a foreign country), invited to the October 2014 unveiling event, discusses the project with Mr. Hu, Nan (left) and Mr. Li. Hongfa, president and CEO of Tralin Paper (right). Paper360º MARCH/APRIL 2015 39

Table of Contents for the Digital Edition of Paper360 - March/April 2015

Guest Editorial
Over the Wire
TAPPI's Centennial: A Celebration 100 Years in the Making
Precision Alignment of Winders
Single-stream Waste Processing
iRoll at Irving
Fully Automated Continuous Digester
Twin Roll Press Upgrade
TAPPI Journal Summaries
Effluent Treatment
Microfibrils to Transform Paper Furnish
Consolidation Watch
Knowledge Builder
New Energy Windfall
Power from Waste
Safety Survey
Association News
Online Exclusives
Advertisers Index

Paper360 - March/April 2015