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The products designed by Sulzer Pumps Finland (see box) for the requirements of the pulp and paper industry (Fig. 1 ) can be divided into the following groups: • Ahlstar™ pumps for stock and 6 SULZER TECHNICAL REVIEW 4/2000 3971 Pumps for the Pulp and Paper Industry PEKKA HAAPANEN SULZER PUMPS The former Ahlstrom Pumps Corporation, which was renamed Sulzer Pumps Finland Oy when it became a part of the Sulzer Corporation in May 2000, launched its first pump for the paper industry more than 100 years ago. Many years’ experience and well-founded knowledge of processes in the pulp and paper industry enable Sulzer Pumps Finland to offer innovative, technically high- quality and reliable pumps for all process stages. 1 The ever-increasing computerization is one of the major reasons for the rise in the consumption of paper. Sulzer Pumps Finland – part of Sulzer since May 2000 – is one of the leading companies in process pumps for the pulp and paper industry, with a high global market share. other liquids associated with the paper making process • Special pumps for applications involving particular require- ments • MCE™ pumping systems and other MC ® equipment • Salomix™ agitators for stock chests and storage towers STOCK PUMPS The pumps of the Ahlstar series are designed for the pumping of stocks, liquors, filtrates, water, rejects, chemicals, additives, slur- ries, sludge and other liquids, which are typically pumped in the paper making process (Fig. 2 ). More than 69 000 of them have been sold worldwide to date to all leading companies in the pulp and paper industry. This series also includes pumps which are de- signed especially for the pumping and also degassing of process liq- uids with a large content of air or gas, i.e. applications where the tra- ditional centrifugal pumps fail. Every Ahlstar pump is tailor-made to ensure process reliability, high efficiency and low operating costs. At the same time, the spare parts inventory and costs are kept to a minimum by means of standard- ization. The Ahlstar APP pumps were developed in particular for the pumping of stock with a consisten- cy of up to 8%. These pumps are capable of pumping “stock just like water”, which means substantial energy savings and a stable process flow. Depending on the characteristics of the medium being pumped, the pumps are equipped with open, closed or spe- cial impellers.

Sulzer Pumps for Paper Industry

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Page 1: Sulzer Pumps for Paper Industry

The products designed bySulzer Pumps Finland (see

box) for the requirements of thepulp and paper industry (Fig. 1 )can be divided into the followinggroups:• Ahlstar™ pumps for stock and

6 S U L Z E R T E C H N I C A L R E V I E W 4 / 2 0 0 0 3971

Pumps for the Pulpand Paper Industry

PEKKA HAAPANENSULZER PUMPS

The former Ahlstrom Pumps Corporation, which wasrenamed Sulzer Pumps Finland Oy when it became apart of the Sulzer Corporation in May 2000, launched itsfirst pump for the paper industry more than 100 yearsago. Many years’ experience and well-founded knowledgeof processes in the pulp and paper industry enable SulzerPumps Finland to offer innovative, technically high-quality and reliable pumps for all process stages.

1 The ever-increasing computerization is one of the major reasons forthe rise in the consumption of paper. Sulzer Pumps Finland – part ofSulzer since May 2000 – is one of the leading companies in process pumpsfor the pulp and paper industry, with a high global market share.

other liquids associated with thepaper making process

• Special pumps for applicationsinvolving particular require-ments

• MCE™ pumping systems andother MC® equipment

• Salomix™ agitators for stockchests and storage towers

STOCK PUMPSThe pumps of the Ahlstar seriesare designed for the pumping ofstocks, liquors, filtrates, water,rejects, chemicals, additives, slur-ries, sludge and other liquids,which are typically pumped in thepaper making process (Fig. 2 ).More than 69 000 of them havebeen sold worldwide to date to allleading companies in the pulp andpaper industry. This series alsoincludes pumps which are de-signed especially for the pumping

and also degassing of process liq-uids with a large content of air orgas, i.e. applications where the tra-ditional centrifugal pumps fail.Every Ahlstar pump is tailor-madeto ensure process reliability, highefficiency and low operating costs.At the same time, the spare partsinventory and costs are kept to aminimum by means of standard-ization.The Ahlstar APP pumps weredeveloped in particular for thepumping of stock with a consisten-cy of up to 8%. These pumps arecapable of pumping “stock just likewater”, which means substantialenergy savings and a stableprocess flow. Depending on thecharacteristics of the mediumbeing pumped, the pumps areequipped with open, closed or spe-cial impellers.

Page 2: Sulzer Pumps for Paper Industry

MAINTENANCE- AND LEAK-FREE SHAFT SEALS

Most of the Ahlstar pumps areequipped with a so-called dynamicseal. In contrast to the traditionalpumps, by which the sealing effectis created by friction, the pump isequipped with an additional smallimpeller (expeller) located in thecasing cover (Fig. 3 ). When theliquid being pumped tries to escapealong the shaft, this small impellerpumps it back again. In the stand-still condition, the liquid presses aflexible disk against the sleeve andthus prevents any possibility ofleak.The dynamic seals do not leak, andthey are practically maintenance-free. Furthermore, they do notrequire any external sealing liq-uid, which simplifies the operationof the pump. The use of these sealseliminates the problems associat-ed with mechanical seals (dry run-ning, occasional or continuousleakage) during the start-up of a mill or department. ExistingAhlstar pumps with core packingsor mechanical seals can also beretrofitted with dynamic shaftseals. Overall, dimensions are thesame, so the pump and the motorremain in the installed position; itis only a matter of replacing therespective parts. More than 23 000Ahlstar pumps are operating withdynamic seals.

PUMPED LIQUID WITH UP TO 70% AIR

The Ahlstar degassing pumps canpump stock at a consistency rangeof up to 8% with a high air or gascontent, foaming liquids andsludge from deinking plants, as

S U L Z E R T E C H N I C A L R E V I E W 4 / 2 0 0 0 7

2 The Ahlstar pumps from Sulzer pumps Finland areused, for example, for the pumping of paper stock. They

pump stock with a consistency of up to 8% just like waterand thus facilitate a reliable and stable process flow.

Expeller

Flexible disk

Sleeve

3 The majority of the Ahlstar pumps – and also thoseinstalled with core packings or mechanical seals – can beequipped with dynamic seals, which are leak-free and requirehardly any maintenance. They can be retrofitted in existingpumps very simply; it is only a matter of replacing the respec-tive parts of the pump (shown in red in the illustration).

SULZER PUMPSFINLAND OY

The former Ahlstrom PumpsCorporation – renamedSulzer Pumps Finland Oy –has been a member of theSulzer Corporation sinceMay 2000. The firm, one ofthe leading companies inpumps for the pulp andpaper industry, launched itsfirst pump designed espe-cially for the requirementsof the paper industry in1891. Sulzer Pumps Finlandachieved net sales of about135 million EUR in 1999, ofwhich about two thirds wererealized by the new compa-ny, i.e. pumps for minorprocess improvements, sin-gle pumps and service re-quirements. The companyhas production units in Fin-land, Singapore and theUSA.The research and develop-ment work is focussed on thespecific requirements of thepulp and paper industry.Pumps, agitators and otherproducts developed for thepulp and paper industry are tested under processconditions at the modern, fullscale R&D centre in Karhula and Salo (FI).

Page 3: Sulzer Pumps for Paper Industry

4 With the Ahlstar ARP degassing pumps, the air-liquid mixture is routedto the rear of the impeller, where an auxiliary impeller separates the liquidand the air. The liquid is led to the inlet side of the pump and the air, forexample, into a collection system.

well as other liquids mixed withgas. Depending on how stronglythe gas or air is bound into thepumped liquid, the gas content canbe up to 70%. The gas is removedby creating a pressure differencebetween the inlet side of the pumpand the degassing chamber locat-ed to the rear of the impeller(Fig. 4). If necessary, the pressuredifference can be created by meansof a vacuum pump. The removal ofthe gas also improves the perfor-mance of the other process equip-ment. In addition, these pumpsreduce the demand for expensivedefoaming agents.The Ahlstar series also featuresother pump types: for instance, theAhlstar NPP pumps. Due to the

open design of the casing andimpeller, they are very suitable forliquids with impurities such asrejects and sludge. The AhlstarWPP wear-resistant pumps areespecially suitable for liquids con-taining abrasive particles such asslurries, rejects, fillers, additivesor sludge. Thanks to their design,the life time of these pumps can be6 to 8 times longer than that of tra-ditional pumps. And since they donot clog, they are also very suitablefor liquids with impurities.

PUMPS FOR SPECIALAPPLICATIONS

The HPP high-pressure, multi-stage pumps are used, for example,as shower water pumps for thecleaning of felts and rollers onpaper machines. Thanks to theirrobust design, they are particular-ly reliable in operation and easy tomaintain. The HPP pump is alsounique in that, with the most diffi-cult applications where the flow

requirement changes from mini-mum to maximum and vice versa,the outstanding reliability of thepump remains uncompromised.Pressure pulsations, initiated bythe headbox feed pump, mightcreate unacceptable variations ofpaper basis weight in the machinedirection. This can have an effecton paper quality.The ZPP headbox feed pump(Fig. 5) as well as the Ahlstar APPlow-pulse, dilution water pumpoperate with very low-pressurepulsations and ensure high paperquality. The ZPP pumps attain anefficiency of up to more than 90%.Since the entire mill productionpasses through these pumps, theyhave to operate in a really reliablemanner. To ensure that the pres-sure pulsations are reduced to anabsolute minimum, Sulzer PumpsFinland attaches great importanceto produce the precision castings ofthe hydraulic parts in its ownfoundry.

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5 Pressure pulsations, initiated bythe headbox feed pump in the paper

machine approach system, can causeunacceptable variations in the gram-mage of the paper. The ZPP headbox

feed pumps operate with the lowestpossible pressure pulsations.

Air

Liquid

Page 4: Sulzer Pumps for Paper Industry

MCE PUMPING SYSTEM OFTHE THIRD GENERATION

The first commercial centrifugalMC pump with degassing wasstarted in a Finnish chemical pulpbleaching application in 1980. Inthe meantime, a third generationof the MCE pumping system hasbeen introduced to the market. Itis designed for larger capacityranges, higher pumping heads,higher pumping consistencies andfor lower energy consumption.With delivery heads of up to 180 m,the pump capacity extends to 4000ADMT/d (350 l/s at a consistency of12%). The MCE pumping systemsare usually used in pulp mills(Fig. 6 ), TMP lines and papermills for the pumping of stockswith a consistency of 8 to 18% fromwashers, thickeners, filters andreaction towers.Other process equipment incorpo-rating MC technology includes theMC Flow Discharger, MC Dis-charge Scraper or Ahlmix™ chem-ical mixers for the mixing ofgaseous and liquid bleachingchemicals, as well as steam intothe stock. By using these equip-ment, the MCE pumping systemssimplify the process, result in eco-nomic pumping and mixing, im-prove the reliability of the mill andreduce the environmental impact.

NO DECAY OF THE FIBROUS STOCK

In addition to pumps, SulzerPumps Finland supplies agitatorsfor stock chests and storage tow-ers. The Salomix™ is a side-mounted propeller chest agitatorand designed for fibrous stocks. Ithas a low power requirement, isreliable in operation and, thanks toits robust concept, easy to main-tain. Other new developmentsinclude the TES top entry spread-er (Fig. 7), which eliminates stag-nant zones where the stock tendsto decay. Furthermore, the VULCA– a vertical, under level, chargingarrangement – prevents air fromentering the stock and reduces thetotal consumption of energy. Ω

F O R M O R E D E T A I L SSulzer Pumps Finland OyPekka HaapanenP.O. Box 18FI-48601 KarhulaFinlandTelephone +358 (0)5-224 30 74Fax +358 (0)5-224 30 06E-mail [email protected]

6 In addition to the MCE pumping system (left), the MC technologyincludes other equipment that can be used in bleaching plants (right).The typical MC pumping system scope of supply comprises dropleg,MCE pump, degassing system, valves and control system.

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7 The Salomix-TES top entry spreaderfor supply towers eliminates stagnant

zones where the fibrous stock fre-quently decays. There isalso the MC pumpingsystem that pumps thestock to the TES topentry spreader.

MCE pumping system

Ahlmix chemical mixer

MC Discharge Scraper andMCE pumping system

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