Turbine G3
New recovery boiler and
turbine at Östrand pulp mill
– delivered by Siemens
The turbine and the generator were supplied
by German Siemens and the two 140-ton
machines were lifted into turbine hall with
hydraulics.
The turbine is equipped with two steam intakes of 105
bar and 57 bar. Bleeding is at four pressure levels and
counterpressure steam is maintained at 3.5 bar. The
turbine is equipped with an open shaft end to facilitate
the addition of a condenser section. The generator was
dimensioned from the beginning to facilitate a counterpressure as well as a condenser turbine.
After two years of work, the new recovery
boiler and turbine at Östrand were placed in
operation in autumn 2006. As a result of the
investment of SEK 1.6 billion, production of
kraft pulp can increase to 420,000 tons per
year. The recovery boiler is designed so that
the pulp mill will be able to increase the production in the future to 800,000 tons annually.
The recovery boiler is designed to provide maximum
electricity production combined with the steam turbine.
The fuel to produce this electrical energy is more than
98% biofuel, mostly black liquor.
Back pressure turbine with the possibility of a complementary
addition with a condensing turbine.
Maximum capacity
Condensation part, future
Steam pressure
Steam temperature
Installed capacity
Generator voltage
75 MW
25 MW
105 bar(e)
515 oC
112 MVA
10.5 kV
PC
105 bar(e),
515 ˚C
PC
57 bar(e),
440 ˚C
G
ca 27 bar(e)
ca 16 bar(e)
11,5 bar(e)
ca 7 bar(e)
3,5 bar(e)
SCA GRAPHIC SUNDSVALL AB
Östrand pulp mill
SE-861 81 TIMRÅ
Tel +46 60 16 40 00
Fax +46 60 57 43 28
www.pulp.sca.com
AN SCA FOREST PRODUCTS COMPANY
PC
To future
condensation
turbine
With the new turbine,
the production of
electrical energy can
be doubled to 500
GWh per year. This
corresponds to the
heating of 25,000
single-family homes
and means that the
kraft plant is more
than self-sufficient in electricity.
Östrand is periodically a supplier of electrical energy.
Despite the CTMP plant consuming a substantial
amount of electrical energy, Östrand will be able to sell
electrical energy quite often. Östrand also supplies heat
to the Timrå Municipality district-heating network.
Electrical power Östrand (Sulphate and CTMP)
2004
2007
Electrical power generation
Electrical power consumption
Total to purchase
242 GWh
478 GWh
236 GWh
468 GWh
500 GWh
32 GWh
Recovery boiler 6
– delivered by Andritz
Östrand’s new soda recovery boiler was delivered
by Andritz and the boiler building is 77 meters
high. A steam temperature of 515 oC was selected
so that the boiler and the turbine would be able to
deliver maximum electricity production. Consequently, the superheaters were over-dimensioned
and produced in specialty steel.
Since the system’s degree of electrical output is
prioritized, the amount of high-pressure steam has
been maximized. This is accomplished through extended preheating of the feed water and combustion
air in several stages. Sootblowing steam is recovered
from a bleed duct in the turbine.
The boiler is fed combustion air at seven different
levels with the aim of attaining high combustion
and low nitrogen oxides emissions. The plant’s
weak gases are also incinerated as secondary air,
which contributes to reduce odor from the plant.
The boiler’s flue gases pass through electrostatic
precipitators (ESPs) with four sections for the best
flue gas separation, then the gases are cooled in a
flue-gas cooler for production of warm water.
The total length of the piping in the boiler body
and connections in the boiler is 330 kilometers,
with a total of about 8,500 welds. All welds were
heat-treated before and after welding to eliminate
unwanted tension in the material.
Initially, the recovery boiler will be over-dimensioned. In addition, it is pre-designed for future
expansion, which is accomplished by moving the
left sidewall and by adding heating surface and a
flue-gas section. The boiler is also equipped for
feeding of sulfur and borate, if required.
Design data
Step 1
2 500 tds/24h
3 300 tds/24h
Step 2
4 400 tds/24h
515 °C
105 bar(e)
383 t/h
144 °C
515 °C
105 bar(e)
703 t/h
144 °C
160 °C
160 °C
20 °C
25 °C
Heavy black liquor
Dry solids content
Heating value
73 %
13,65 MJ/kgds
80 %
Air of combustion
190 °C
190 °C
12,5 tds/24h/m2
1 990 kW/m2
11,3 m
13,5 m
152 m2
39 m
21,7 tds/24h/m2
3 440 kW/m2
15,0 m
13,5 m
202 m2
39 m
Capacity, MCR excl. ashes
*max capacity
Steam and boiler feed water
Steam temperature
Steam pressure
Steam flow, net
Feed water tank temperature
Feed water, temperature
before economizer 1
Feed water, rise in temperature
between economizers
Furnace
Black liquor load
Width
Depth
Area, bottom of furnace
Height to “nose arch”
Tertiary
Materials
Primary ÖH (1A, 1B)
Secondary ÖH (2)
Tertiary ÖH (3)
Quartenary ÖH (4)
Qvintenary ÖH (5)
Secondary
Walls
Bottom
Primary
16Mo3
16Mo3
10CrMo910
10CrMo910
10CrMo910
X10CrMoVNb91
Sanicro 28
Compound
Carbon steel
Sanicro 38