Lignite drying in a lignite fired power plant with a heat pump

A lignite fired steam power plant comprising:

• a water/steam power cycle having:
• a pressure series of steam turbines;
• a condenser, at a low pressure end of pressure series of steam turbines, configured and arrange to condense a steam exhausted from the low pressure end of the pressure series of steam turbines;
• and
• a low pressure condensate system, arrangement downstream of the condenser, adapted to preheat a condensate from the condenser;
• a dryer system for drying lignite coal, the dryer system having:
• a dryer;
• a first outlet line for removing a vapour from the dryer;
• and
• a heat pump circuit, configured and arranged to provide heat energy to the dryer, comprising:
• a first working fluid;
• a dryer heat exchanger in the dryer;
• an expansion device fluidly connected and downstream of the dryer heat exchanger;
• an evaporator heat exchanger fluidly connected to and downstream of the expansion device and further connected to the first outlet line so as to enable heat energy transfer from the vapour of the first outlet line to the first working fluid;
• a compressor, fluidly connected to and downstream of the evaporator heat exchanger and upstream of the dryer heat exchanger, for compressing the first working fluid;
• a steam makeup line, extending from the pressure series of steam turbine to a first point fluidly between the dryer heat exchanger and the compressor;
• and
• a condensate return line extending from a second point fluidly between the dryer heat exchanger and the expansion device to the low pressure condensate system so as to return a condensate from the heat pump circuit into the water steam power cycle.