Exergy analysis of advanced boiler flue gas heat recovery system in power plant

One of the effective energy saving methods is recovering flue gas waste heat from power station boilers to heat condensation water, which put the waste heat into steam regenerative cycle. A general power profit model of boiler flue gas heat recovery system (BFGHRS) was established by using exergy analysis method. The traditional BFGHRS was discussed extensively and the deficiency of overlarge exergy loss in air preheater was pointed out. Furthermore an advanced BFGHRS was proposed, which combines air preheater with the traditional BFGHRS. Basing on the parameters of a 1000 MW supercritical unit thermodynamic system, the power profit analysis of the advanced BFGHRS was accomplished. The results show that, compared with the traditional BFGHRS, the advanced BFGHRS flue gas energy level is doubled and the plant exergy efficiency is increased 0.75% at the flue gas temperature drop of 35°C because of the exergy loss decrement of the air preheater unit. © 2012 Chin. Soc. for Elec. Eng.