Energy efficiency is still the focus

Energy efficiency is still the focus

Suppliers/research institutes £¨ n. ѧ»á£¬Ð-»á£»Ñ§Ôº£»vt.

¿ªÊ¼£¨µ÷²é£©£»Öƶ¨£»´´Á¢£»ÌáÆð£¨ËßËÏ£©£©working to ensure TMP does

not mean ¡°too much power¡±

___by Graeme Rodden ,

Editor

Speaking at the opening of Metso Paper¡¯s £¨ÃÀ׿ÔìÖ½»úеµÄ £©new pilot

CTMP/TMP refining line£¨¾«Á¶Ïß £©,executive

vice-president£¨Ö´Ðи±×ܲà £© Aarto Aaltonen said that enrergy

cosumption was still the biggest issue facing mechanical pulping.¡±In

the last 20 year,there has not been a significant advancement in this

area,only incremental £¨adj. Ôö¼ÓµÄ£¬ÔöÖµµÄ£©improvements.The

challenge remains.¡±

Refining techology faces other challenges as well. Increasing capacity

is one.Aaltonen notes that when mechanical pulping technology was

introduced in the late 1970s,motoer capacity was limited to 35 MW and

8-10 refiners were needed to produce enough pulp for a paper

machine.Now,it is possible to produce enough pulp from a single line

(2-3 refiners).Power ranges are 30+ MW.

Fiber property tailoring is another issue.Pulp must be tailor made to

meet each papermaker¡¯s needs.This requires a close look at refiner

plate design.

Finally,Aaltonen mentioned the use of different wood species.For

example,in China,the wood is different and since China is the place

where new capacity is being installed ,¡±we must learn to use their

wood,¡±says Aaltonen.

So,although mechanical pulping may be considered a mature

technology ,research and development continues,particularly in the

fields of energy consumption and pulp properties.

Suppliers at work

On the suppliers¡¯ side ,Andritz offers its P-RC APMP and its RTS

processes.The P-RC process preconditions the chips with a high

compression treatment .Alkaline perxide impregnation at a controlled

temperature follows.Then,the refiner acts as a good chemical micer and

reaction takes place in the high consistency tower.The refiner chemical

treatment develops brightness and strength,remove COD and extractives

and reduces energy use .

The benefits of P-RC APMP include a lower capital investment cost and

low operating costs.The process is flexible and energy savings copare

with a CTMP system may be as high as 25%-35%.It works with softwood

or hardwood.End uses run the range of paper

grades:tissue,printing/writing/newsprint and paperboard.

Andritz has three plants in China and one Iran due for startup in 2003.All

use a hardwood furnish.

The RTS (retention time ,temperature,speed) process is designed to

reduce refining energy and optimize pulp ,paper and printing

quality.Increased refiner speed results in higher intensity refining

and faster transfer of energy .Therefore,less energy is required to

reach a freeness or quality target.The increased temperature softens

cell wall layers.The increased temperature softens cell wall

layers.This leads to increased tear,bonding strength and reduced

shives.Reduced residence time controls heating time to preserve

brightness,opacity and bleachability.

Andritz has 15 line operating in 10 mills worldwide ,again providing

pulp for a range of end products:new,LWC,boarc and SC-A+.At one of the

mills¡ª¡ªStora Enso Port Hawkesbury (Canada)¡ª¡ªthe supplier has

recieved an EPC order to increase production of two extsting RTS lines

to 1300 tonnes/day from 1000 tonnes/day (two lines of three-stage

refining ).

The increased production will be split among the mill¡¯s SC-A and

newsprint paper machines.The SC-A line will receive 900-1000

tonnes/day.The will be the largest TMP production lines in the world

for SC-A paper.

To achieve the increased production,the 24MW motors on the primary

refiners will be replaced by 32 MW units from ABB.Other work includes

upgrades to the gear increasers to continue RTS refining at the higher

production rate,the addtion of plug screw feeders before each secondary

refiner,modifications to the steam and sceen piping and MC pump

upgrades.

Research at Andritz is centered on improving end product properties

and minimizing operating costs and effects on the environment .The

company recently introduced RT Fiberizer ,a way to reduce energy

consumption while improving impregnation efficiency .In the bleaching

end R&D efforts are focused on using chemicals that have less effect