POWER May 2014 - 46

FUELS
the material back to the furnace. The result
is much-improved combustion efficiency and
fewer emissions. The guaranteed boiler efficiency
was 91% with guaranteed emissions
of 200 mg/Nm3
NOx and 200 mg/Nm3
SOx
.
A variety of biomass is transported by
trucks to the plant unloading station and conveyed
to silos in the storage yard. There are
three separate storage silos, each dedicated to
forest and woody biomass, and five separate
silos for agro biomass. Each agro fuel is fed
from its own silo, as the fuel mixture consists
of straw pellets, oat husk, cherry stones,
rapeseed cake, and energy willow.
The system allows the dosing of different
types of biomass using screw conveyors in order
to feed a homogenous fuel mixture to the
boiler fuel silos. The mixture of different types
of biomass is distributed evenly to the CFB
boiler by four feeding points. The fuel is fed to
solid return chutes from external integrated heat
exchangers and mixed with circulating material
before entering the furnace.
Polaniec Power Station, Poland. GDF
Suez Energia Polska SA's 1,800-MW coalfired
Polaniec Power Station is the fifthlargest
power plant in Poland (Figure 4). It
consists of eight units, each with a capacity
of 225 MW, built between 1979 and 1983.
In April 2010, GDF Suez Energia began
construction of the world's largest CFB
boiler designed to fire 100% biomass at its
Polaniec plant site, and the plant-known as
the Polaniec Green Unit (a POWER renewable
Top Plant, see the December 2013 issue
at powermag.com)-was commissioned on
Nov. 15, 2012.
The FW Advanced Bio CFB combustion
technology was selected for the plant that
now produces 205 MW using a broad range
of biomass fuels. The wood and agro biomass
fuel is composed of 80% wood and 20% agro
biomass. The wood portion is clean wood
from forestry residues. The agro portion includes
a variety of agricultural biomass such
as straw, sunflower pellets, dried fruit, and
palm kernel shell.
The boiler is equipped with an ammonia
injection system and catalyst-selective non5.
Unique fuel mix. Alstom is constructing
for Narva Elektrijaamad AS a plant
that will cofire oil shale, peat, and wet wood
chips. Estonia has significant domestic oil
shale resources. Courtesy: Alstom
6. Building from scratch. This artist's rendering depicts KOSPO's 2,200-MW Green
Power CFB Plant, located in Samcheok, on the shoreline in northeast South Korea. The plant
will become the largest CFB power plant in the world when it goes online (scheduled for mid2015).
The plant will burn both high- and low-rank coals and will sit on 2.5 million square meters
of reclaimed land. Source: Foster Wheeler
catalytic reduction (SNCR) plus SCR-for
controlling NOx
emissions, and an electrostatic
precipitator for controlling particulate
emissions. Boiler steam conditions are 127
bar and 535C. Emissions guarantees, based
on a 24-hour average, are 150 mg/Nm3
150 mg/Nm3
NOx
SO2, and 50 mg/Nm3
CO.
The boiler has operated well with various
fuel mixes and continues to operate with
high efficiency. Boiler operation responds to
requirements of electricity production, and
full load range is in use on a weekly basis.
The boiler fulfills all Polish grid requirements
with a 4% minimum load change rate
demonstrated solely with solid biomass fuels
with a turndown to 40% of design load.
Narva Elektrijaamad AS, Estonia. Alstom
is constructing a 300-MW CFB boiler
plant for Narva Elektrijaamad AS (affiliate
of Eesti Energia), located near the Russian
border in Estonia (Figure 5). The Eesti Power
Plant, built between 1963 and 1973, was
originally constructed with 16 boilers and
eight 200-MW steam turbines. Eesti was selected
as the site for the utility's new fuelflexible
CFB boiler that is designed to burn
low-heat-content fuel mixtures of oil shale
(8.2 MJ/kg), peat (8.75 MJ/kg), and up to
50% cofiring of wet wood chips (50% water
by weight, 8.35 MJ/kg), all LHV.
The unique combination of fuels has an
unexpected benefit. The inherent calcium
content of the oil shale facilitates high natural
sulfur removal, and the 200 mg/Nm3
on SO2
limit
emissions will be met without adding
additional limestone to the CFB furnace.
46
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,
The low combustion temperature of the
CFB furnace also produces less than the NOx
limit of 150 mg/Nm3
without an additional
denitrification system despite the high NOx
emissions produced when combusting peat.
An electrostatic precipitator removes the
particulate emissions from the stack gas. Alstom
guaranteed a boiler efficiency of 92.3%
(LHV) based on a steam pressure of 178 bar
and superheat/reheat steam temperatures of
543C/568C. The plant is scheduled to enter
commercial service in October 2015.
Samcheok Green Power Plant, South
Korea. Korean Southern Power Co. (KOSPO)
also concluded that fuel procurement
flexibility would save the company millions
of dollars in fuel costs over its new plant's
life. KOSPO selected CFB technology for its
2,200-MW Green Power Plant project, perhaps
one of the most ambitious power projects
ever undertaken in South Korea. KOSPO
describes the project as the most efficient and
greenest coal plant ever built. When completed
(expected by 2020), the facility will house
5,000 MW of power generation, including
renewable energy projects (Figure 6).
The Samcheok plant is located in Gangwon-do
Province in northeast South Korea
on 2.5 million square meters of reclaimed
coastal land. Now under construction, the first
phase uses four 550-MW FW CFBs featuring
the world's first CFB boilers operating at
ultra-supercritical steam conditions (257 barg,
603C/603C), which is a scale-up of the Lagisza
plant design. The CFBs will be the most
advanced CFB boiler units in the world when
POWER | May 2014

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POWER May 2014

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