TY - JOUR
TI - Investigation of pre-drying lignite in an existing Greek power plant
AU - Agraniotis Michalis
AU - Karellas Sotirios
AU - Violidakis Ioannis
AU - Doukelis Aggelos
AU - Grammelis Panagiotis
AU - Kakaras Emmanouil
JN - Thermal Science
PY - 2012
VL - 16
IS - 1
SP - 283
EP - 296
PT - Article
AB - The application of lignite pre-drying technologies in next generation of  lignite power plants by utilizing low pressure steam as a drying medium  instead of hot recirculated flue gas - combined with thermal utilization of  the vaporized coal moisture - is expected to bring efficiency increase of 2-4  percentage points in future lignite power plants compared with today’s state  of the art. The pre-drying concept is of particular importance in Greek  boilers firing lignite with a high water and ash content. The combustion of  Greek predried lignite has been investigated experimentally and via numerical  simulations in our previous research. This study focuses on the potential  integration of a lignite pre-drying system in an existing Greek power plant  with dry lignite co-firing thermal share of up to 30%. The radiative and  convective heat fluxes to the boiler and the overall boiler heat balance is  calculated for reference and dry lignite co-firing conditions by an in-house  calculation code. The overall plant’s thermal cycle is then simulated using  commercial thermal cycle calculation software. The net plant efficiency is in  this way determined for reference and dry coal co-firing conditions.  According to the simulation results the integration of a pre-drying system  and the implementation of dry lignite co-firing may bring an efficiency  increase of about 1.5 percentage points in existing Greek boilers. It is  therefore considered as an important measure towards improving plant  efficiency and reducing specific CO2 emissions in existing plants.