Environmental Technologies and Eco-innovation in the Czech ...

The steam being produced by existing electrical boilers does not reach critical
specifications. This means that the steam pressure reaches a maximum 18 MPa, and its
temperature fluctuates between 540 and 580 °C. This allows for maximum clean energy
efficiency 6 at a range of 32–35%. In order to increase the energy efficiency, decrease
airborne release contaminants and achieve fuel savings, better systems called “clean
coal technology” have been developed.
2.4.1 | Pulverized coal combustion with supercritical steam specifications
To achieve more efficient power units, boilers and power units (including
turbines) that work with supercritical steam specifications have been constructed.
Power units that use above critical specifications reach a steam pressure of 25–31.5 MPa
and a steam temperature of 600–610 °C. This allows for clean energy efficiency ranging
between 42 and 43%. Power units working with a pressure of 35 MPa and a steam
temperature of 700 °C and able to achieve clean energy efficiency up to 50% are being
developed. As a result of increasing the thermal efficiency of power plants, a smaller
amount of fuel is being used for producing the same amount of electricity, and
airborne release contaminants have significantly decreased.
A newly constructed unit at the Ledvice power plant with supercritical parameters
will allow for clean efficiency between 42 and 43% (with gross efficiency of 47%),
using steam pressure of 28 MPa and a temperature of 600–610 °C. A comparison of two
“subcritical” units in operation at the Ledvice power plant with the “above critical” unit
is shown in Table 4.
If the existing units in Czech power plants are modernised with the technology listed
in Table 4 having supercritical parameters, a significant contribution to environmental
protection in the form of savings of emissions into the atmosphere can be expected
compared to the use of the technology with subcritical parameters.
6 energy efficiency – the ratio of energy included in the input fuel against the electrical output of a power plant as measured at
the generator