Fluid Engineering presents Sulzer’s AHLSTAR UP

AHSTARUP – A Modern Range of Stock

and Process Pumps for Constant Energy Consumption Savings and Enhanced
Operational Reliability without Sealing Water

AHLSTARUP further development of the
reliable AHLSTARTM stock and process pumps, also known as APT pumps,
used in the pulp and paper industry all over the world.

The continuous improvement of processes in the pulp
and paper industry requires better machines, components and pumps. This leads
to a need for enhanced reliability to ensure higher availability and
operational safety, extend maintenance intervals, improve cost effectiveness of
pumps through a higher efficiency factor and achieve the best possible coverage
of the entire pump spectrum to reduce power requirements. Furthermore, it is
important to provide designs that are easy and quick to maintain and offer
shaft seal concepts that are dependable without needing sealing water.

There is also an increasing demand for more
standardization and compatibility of modular structures, both to reduce the
cost of spare inventories and to be able to adjust the performance of existing
pumps to new operational conditions by exchanging hydraulic components. Sulzer
Pumps took these needs as their guide for the development of the AHLSTARUP.

The foundation for this ongoing development has
been, and still is, long-standing experience and knowledge about the specific
processes and requirements of the pulp and paper industry.

1. Sulzer Stock Pumping Concept
part of the Sulzer stock pumping concept, which also comprises KCETM, LCETM, and
MCETM pumping systems (Fig. 1). This
stock pumping concept is again a part of the Sulzer product family for various
applications in the pulp and paper industry, in pulp production, pulp drying
machine, chemical recovery, stock treatment, short circulation for the paper
machine and the paper machine itself as well as waste water clarification (Fig. 2).

2. New Hydraulics
There was a comprehensive
catalogue of requirements for the new A-hydraulics of the AHLSTARUP.
Amongst the following key elements were identified:

  • High
    efficiency over a wide performance range.
  • An impeller
    design that can pump clean, abrasive and corrosive liquids and stock of various
    kinds up to a stock consistency of 8%.
  • a second
    impeller that can pump stock up to a consistency of 8% and liquids with long or
    large solid particles.
  • Good coverage
    of the entire pump spectrum by an optimal number of pump sizes.
  • High suction
    capability and low NPSHr over a wide performance range.
  • To optimize
    the entire hydraulic range while maintaining the size of the pump, increase the
    hydraulic performance, capacity, head and efficiency of the AHLSTARUP
    compared to the AHLSTARTM and to reduce the NPSHr-value.
  • To reduce wear
    caused by the pumped liquid using a design optimizing flow in the pump (Fig. 3).
  • Maintain
    specific hydraulics, e.g. N-hydraulics for pumping liquids with large or long
    solid particles or W-hydraulics for pumping highly abrasive and erosive liquids
    such as lime mud (Fig. 4).

3. Sulzer WaterLessTM Shaft Seal Concept
The shaft seal deserves
special attention because it accounts for about 65% of all problems with pumps
(summary of experience from different industrial branches). Sulzer has already
considered this point by developing and introducing dynamic seals for the
AHLSTARTM.  Since dynamic seals can not be
used in certain applications, Sulzer developed the WaterLessTM Shaft Seal
Concept for the AHLSTARUP. The complete WaterLessTM Shaft Seal
Concept features improvements on the reliable dynamic seal plus single and
double mechanical seals which were developed in cooperation with John Crane
Safematic. The shaft seals have common dimensions and can be readily exchanged
due to the modular design of the AHLSTARUP with A-, N- and W- hydraulics when
they have the same size bearing unit (Fig.

can also be equipped with gland packing, although this type of sealing is
rarely used.

3.1 Dynamic Shaft Seal
This is a non-contact seal
solution that does not need any sealing liquid (sealing water) and therefore
does not need any system for the sealing liquid or wastewater treatment. The
new static seal prevents solid particles from entering through the sealing gap
and reduces operational wear (Fig. 5).
More than 30,000 pumps [as of the second quarter of 2006] in the pulp and paper
industry worldwide have been equipped with dynamic seals to date.

3.2 Mechanical Seals
The single mechanical seal
does not require any external sealing liquid. By introducing a special design
feature there is continuous lubrication by liquid pumped. The double mechanical
seal always needs external sealing water. By using SmartFlow more than 90% of
the sealing liquid can be saved (Fig. 4).
All parts of the mechanical seals are always installed to the end stop, no
measuring needed, which prevents installation mistakes.

4. Sulzer Selfprime and DegasTM Concept
(self-priming and degassing)

Since the processes in the
pulp and paper industry have been continuously improved, e.g. higher speed,
shorter storage periods in smaller chests, etc., the content of gas and air in
the stock has increased.

Sulzer has already applied
the so-called “gas separating pump” with external vacuum pump and the
“self-priming pump” with internal vacuum pump for these problematic
applications. Both systems had been revised before they were integrated into
the AHLSTARUP and are available for all three hydraulic series (A-,
N- and W- hydraulics) (Fig. 6).

5. Sulzer Bearing Unit Concept
Oil and grease lubrication
are possible, “Inpro SealTM“, used to seal the bearings, is a reliable
and wear-free labyrinth seal, which is used on both sides of the bearing unit (Fig. 3).

6. Installation
We kept the proven
torsion-resistant T-shaped base plate fixed at three locations. Part of the
standard delivery package are adjusting screws for an easier alignment of the
motor and raiser blocks for later installation of a larger motor frame size (Fig. 7).

7. Exchangeability of AHLSTARTM (APT) with AHSTARUP
AHLSTARTM (APT) pumps are exchangeable as both have identical external key
connection dimensions. The performance of an existing AHLSTARTM APT can be
increased by exchanging the casing, impeller and the side plates with AHLSTARUP
(Hydrofit). Installed AHLSTARTM pumps can also be converted to the WaterLessTM
Shaft Seal System or the new Bearing Unit Concept (Retrofit).

8. Sulzer Environmental Concept
considerations have also been of priority for these innovations and changes.
Lower power consumption, almost no leakage both of the liquid pumped and the
oil or grease used for lubrication plus no or an extremely low demand for
sealing liquid means protection of resources and the environment (Fig. 8).

9. Summary
further development of the market leading AHLSTARTM stock and process pumps that
are installed in the pulp and paper industry worldwide. The high reliability of
AHLSTARTM has been increased by

  • Optimizing
    shaft sealing with new systems (single and double mechanical seal)
  • New static
    seal arrangement for the dynamic shaft seal
  • Revising gas
    separation of the “degassing pump”
  • Improved wear
    resistance through new hydraulics (casing and impeller)
  • Higher
    reliability of the bearing unit through better lubrication and bearing sealing
  • Completely
    revised hydraulics with higher efficiency factor, lower NPSHr-values and better
  • Modular
    AHLSTARUP exchange units to fit existing AHLSTARTM pumps, e.g.
    complete pumps, exchange units and bearing units.

Kurt Meinl; Sulzer Pumps (Germany) GmbH
Presentation at Exhibitor-Seminar
Zellcheming 2006
Reprinted in Professional Papermaking 2
– 2006; p. 23-25.

Comments are closed.