To study the effect of decarbonization on thermal power units

a simulation model is established to analyze the performance changes of the conventional scheme of carbon capture retrofitting in thermal power units.Moreover

a zero-output scheme of a low-pressure turbine is further proposed to improve the flexibility of the units.The conventional method uses the exhaust steam of the intermediate-pressure cylinder as the reboiler heat source

and the zero-output scheme of the low-pressure cylinder cuts off the low-pressure cylinder inlet steam. On one hand

the two methods are analyzed separately by taking a 300 MW coal-fired power unit as an example. On the other hand

the effects of the two schemes on thermal power units of the whole province is predicted by taking a province in northwest China as a research object. The results show that

the unit output range under the conventional scheme is reduced from 87～300 MW to 147～217 MW

and the power supply efficiency under rated operating conditions decreases from 37.32% to 27.02%. The minimum unit load ratio increases to about 70%. The unit load range ise widened to 47～217 MW when the zero output scheme of the low-pressure cylinder is adopted

which is 2.44 times of that of the conventional scheme. For the discussed northwestern province

the thermal power output range is reduced from 1 103～3 940 MW to 1 875～2 793 MW under the conventional scheme

and the output range is widened to 550～2 793 MW under the low-pressure cylinder zero output scheme.