Based on different arrangement modes of air-extracting system for dual-backpressure condenser

and combined with analysis of practical examples

the influence of arrangement mode for air-extracting system upon the difference value between high-pressure and low-pressure of the dual-backpressure condenser has been analysed and studied

results show that the advantage of series connection mode is little capital investment

but it is easy to make the high-pressure and low-pressureof dual-backpressure condenser can't reach the designed values at the same time

and even result in without pressure difference between high-pressure and low-pressure.In parallel connection mode

the high-pressure and low pressure system is mutually separated

the pressure in condenser and the terminal temperature difference in heat transfer

all can reach the requirments of design.It is recomended that the air-extracting system of newly constructed units should be designed according to the parallel connection mode

the units already in operation can be considered to optimize and retrofit into parallel connection mode

so as to give full play to the superiority of technological and economic advantages of the dual-backpressure condenser.