easier. On arrival at the plant, the fuel
will be unloaded using a ship unloader
rated at 1600 tonnes/hr. Conveyors
then move the fuel to 16 circular
silos. Each silo measures 27 m
in diameter and is 30 m high, providing
a total storage capacity of 260
000 m3. The silos will include a sloped
bottom to accommodate the vibrating
floor, necessary for the correct reclaiming
of the fuel from the silos.
The plant can be fed from any silo,
which allows separation of different
cargoes along with fuel blending. The
fuel delivery system is designed to
supply wood pellets and chips to the
boiler at a rate of 660 tonnes/h and the
plant will burn more than one million
tonnes of biomass fuel each year.
When completed, the fuel unloading
and handling system will be one of
the largest in the world for a biomass
power plant.
The low-sulphur wood pellets contain
little moisture (5 per cent), ash
(1 per cent), and sulphur (0.02 per
cent) and therefore produce low
emissions. The emission limits set for
this project are in line with the new
IED and LCD BREF emission limits
covering multiple pollutants. The
controlled pollutants include sulphur
dioxide/trioxide (SOx), nitrogen oxides
(NOx), dust, carbon monoxide
(CO), ammonia (NH3) slip, mercury
(Hg), hydrogen chloride (HCl) and
hydrogen fluoride (HF).
The pellets also have an excellent
fuel heating value of 17.8 MJ/kg.
When the wood pellets are mixed
with 30 per cent domestic wood chips
with 18.5 per cent moisture content,
the fuel heating value is reduced to
14.95 MJ/kg. The mixing ratio is
highly variable and the boiler is capable
of burning up to 100 per cent
pellets at full load.
Steam conditions in the Teesside
boiler reflect recent technology advances
that will also produce increased
efficiency. For example, Polaniec
Unit 8 produces steam at 127.2/20
bara at 535°C/535°C (superheat/reheat).
Although higher steam parameters
have been applied to some extent
in smaller industrial boilers, it has
become more important in large utility
size boilers firing biomass aiming
for maximum steam cycle efficiency.
The Teesside boiler SH/RH (superheat/
reheat) steam conditions will
therefore be 229/205 kg/s, at a pressure
of 176/43.8 bara and temperature
of 568/568°C. The clean fuel selected
allows these high steam
pressures, which is about the maximum
applicable in natural circulation
boilers. These higher steam conditions
will ensure plant efficiency exceeds
the 36.5 per cent achieved at
Polaniec 8.
The steam cycle design also includes
provisions to deliver lowpressure
steam to a wood chip dryer,
on the order of 6 MWth, to reduce
the moisture content of the incoming
wood chips.
According to Sumitomo SHI FW,
the Teesside boiler will be its most
advanced biomass CFB to date. “It is
the first time that steam parameters
will be at such a level for a biomassonly
plant,” noted Jäntti. “The boiler
utilises the highest steam parameters,
which contributes to the highest efficiency.
It will also utilise advanced
flue gas heat recovery systems to reduce
the flue gas temperature before
it goes to the stack. It will be the most
efficient biomass fired plant when it
begins commercial operation.”
Sumitomo SHI FW says that with
Special Project Supplement
fuels, Teesside will fulfil the most
stringent emission limits set for traditional
(35 mg/m3n SO2, 140 mg/m3n
NOx, 50 mg/m3n CO, and 5 mg/m3n
dust) air emissions.
The use of wood pellets is not only
important in terms of emissions but
also with regard to the physical dimension
of the boiler. Although
Teesside will be the largest of its
kind in terms of power output, it will
be smaller than the latest CFB units
firing fossil fuels.
Giglio explained: “The sizing of
the unit depends on the fuel. Biomass
typically contains a lot of moisture,
which turns into gas. So the furnace
has to be big enough to accommodate
that gas. You therefore end up with a
big furnace, without making a lot of
steam.
“In the case of Teesside, however,
we have dry pellets. Pellets are a
very compact way of transferring the
most energy in biomass. Because
you take the air and moisture out of
the cargo, you’re shipping more
BTUs. Pellets give you that concentrated
form of energy from the biomass.
That’s why when you go to
this size, you need to use pellets for
a large, secure supply of fuel.”
The dry, high-quality fuel essentially
gives Teesside a 50 per cent increase
in plant rating. Its use also
makes fuel transport and handling
THE ENERGY INDUSTRY TIMES - NOVEMBER 2017
3-D aerial view: Teesside is
built around a Sumitomo
SHI FW CFB boiler and a
single steam turbine, along
with a fuel storage area and
conveyor system, a wood
chip drier, and air-cooled
condenser
Table 1. Sumitomo SHI FW has commissioned over 20 CFB
plants firing biomass alone
Start-up year Sumitomo SHI FW Country MWe
2020 Teesside Ltd. UK 299
2016 Spectrum Coal & Power Ltd. India 50
2016 United Renewable Energy Japan 20
2016 Emami Cement Ltd. India 30
2016 Monbetsu Biomass Japan 45
2016 Summit Energy Japan 75
2015 Kirisima mokushitsu Hatsuden Japan 5
2015 Miyazaki shinrin Hatsudensyo Japan 5
2015 Oji Engineering Green Energy Hokuriku Japan 5
2015 Oji Green Energy Ebetsu Japan 25
2015 Green Biomass Factory Japan 6
2015 GS E&C South Korea 105
2015 Oji Green Energy Nchinan Japan 25
2014 Kraftringen Energi AB Sweden 35
2013 Green Energy Japan 6
2015 Nihon Kaisui Japan 19
2012 GDF Suez Energia Polska Poland 205
2012 Asahi Kasei Chemicals Japan 186
2012 PAK, S.A. Poland 55
2010 Prokon Nord Belgium 26
2010 Kawasaki Biomass Power Japan 33
2010 Kaukaan Voima Oy Finland 125
2009 Söderenergi Sweden 85
2008 NV Huisvuilcentrale Noord-Holland (HVC-NH) Netherlands 28
2008 Nippon Paper Industries Japan 41
A 3-D view of the boiler island