The pulverized coal (PC) plant modeled below produces both electricity and warm water for district heating (DH). This plant uses a high efficiency double reheat supercritical steam cycle with nine feedwater heaters. The high pressure turbine inlet conditions are 4050 psi/1080°F (279 bar/582°C), the first reheat conditions are 1150 psi/1110°F (79 bar/599°C), the second reheat conditions are 360 psi/1110°F (25 bar/599°C), and the condenser pressure is 0.7 psi (48 mbar). With these steam conditions, the plant has a gross output of674 MWe, a net output of 552 MWe, a net LHV efficiency of 30%, and is heating 9800 tonnes/hr of water to 90°C. For comparison, a similar plant without a CO2 capturing system would yield a net LHV efficiency of 42%. When equipped with a conventional MEA-based CO2 capturing system without DH heat recovery, such a plant would have a net LHV efficiency of 31%.
Since this plant burns coal, an Electrostatic Precipitator and a Flue Gas Desulfurization unit have been added to the flue gas stream to limit particulate and SOx emissions, respectively. The plant also has a CO2 capture system utilizing an amine-based chemical absorption process to separate the 90% of the CO2 from the other components of the exhaust stream. During the separation process, a substantial amount of low-grade heat is rejected to cooling sources. The temperatures at which much of this heat is rejected are too low to make it useful for power generation, but, in some cases, they are high enough to be used to heat DH water. Approximately 52% of the heat used for DH is recovered from the CO2 separation process. Once separated, the CO2 is compressed to 2200 psia (152 bar) for delivery to its final destination.
CO2 Capture Component