İÇDAŞ POWER PLANT
In our power plant; fluidized bed combustion technology is used which is a clean coal technology (CCT) process. Coal is used as the main fuel and natural gas as auxiliary fuel in our plant. Coal is transferred from the stock area to the boiler through a covered conveyer belt system. Coal is burned inside the fluidized bed boiler with addition of limestone. The gases emitted as a result of combustion pass through the electrostatic dust-holding filters and then directed to the chimney as dust-free. Besides achieving better coal burning with the fluidized bed combustion technology, the SO2 and NOx emissions remain below the desired limits in terms of environmental requirements due to the added limestone and the low burning temperature respectively.
FLUIDIZED BED TECHNOLOGY
Fluidized bed technology is the most recent clean coal burning technology in the world which is developed as a result of R&D studies and began to be used at an increasing rate since the beginning of 1990s. This technology is widely used in the developed countries such as USA, Germany, France, Italy, Japan, South Korea and in the developing countries such as Poland, Czech Republic, China, Thailand, Indonesia, India and Mexico and its usage increases rapidly also in the other countries of the world due to its environmental friendly nature.
In the fluidized bed combustion system; sand, coal and limestone are fluidized in the combustion chamber of the boiler with the combustion air provided from the bottom and the coal is burned without pulverisation in (0-9) mm dimensions in the boiler.
The low combustion temperature (850ºC) in the fluidized bed technology, reduces the oxidisation of air introduced nitrogen (thermal Nox generation) to a minimum level. The NOx emission generated by the fuel nitrogen can be reduced to an extremely low level by gradual air introduction technology. As a result, the NOx emission is very low. Whereas in the Pulverized Coal (PC) technology; the NOX emission is high due to high combustion temperatures (1200ºC) and this necessitates additional clean-up systems.
The high SO2 emission in the Pulverized Coal (PC) boilers is removed with the wet system using lime-wash in the additionally constructed Flue Gas Desulphurisation (FGD) facility. However, environment pollutant effluents are generated at the end of the process in this system. In the fluidized bed combustion system, the gases can be separated from the SO2 through the reaction indicated below by addition of limestone with the coal.
CaO + SO2 + ½ O2 —> CaSO4
The small particles carried by the gases in the boiler during the combustion process are fed back to the boiler through the cyclones located at the outlet of the combustion chamber. In this way, the dust emission is reduced, the period for the coal and limestone remaining in the boiler is extended and hence, the combustion and sulphur retention performance is increased.
A most advanced electro-filter unit, which is comprised of two channels and five partitions, forming 10 cells in total, functioning electro-statically with a 99,98% high efficiency is installed in our facilities for the dust emissions. Under actual circumstances, the dust emission in our facility is significantly below the European limits.
The emission values in our facility are controlled by constant monitoring with an on-line measurement system, operated in an electronic medium. The values measured so far in our facility are well below the European Flue Gas Emission values.
In fluidised bed stations, a great number of air fans and blowers are needed. For this reason, the electrical energy consumed internally is much more than the electrical energy consumed in the pulverised coal stations. Nevertheless, as in compliance with our environmental policy, as an environment friendly and clean coal burning technology, the proven fluidised bed combustion technology is preferred in our facility.