Aspen7.2间歇精馏运行报错 BLOCK B3 FAILED TO CONVERGE AFTER 0 ITERATION(S)

请教各位：

                近来采用Aspen7.2做间歇精馏模拟，出现下列错误：
SEVERE ERROR
   FLASH RESULTS ARE WITHIN TOLERANCE, BUT MAY BE UNSATISFACTORY BECAUSE
   EXTRAPOLATED EOS VAPOR VOLUME ROOT WAS USED FOR PROPERTY CALCULATIONS.


** ERROR
   BLOCK B3 FAILED TO CONVERGE AFTER 0 ITERATION(S).


*** SEVERE ERROR
      FLASH CALCULATIONS FAILED TO CONVERGE IN  11  ITERATIONS.   BUBBLE POINT
      CALCULATION HAS DRIVEN THE TEMPERATURE DOWN TO THE LOWER LIMIT OF
      78.9000 DEGREE K.  BUBBLE POINT TEMPERATURE MAY NOT EXIST AT THE
      SPECIFIED PRESSURE.  FLASH RESULTS ARE WITHIN TOLERANCE, BUT MAY BE
      UNSATISFACTORY BECAUSE EXTRAPOLATED EOS VAPOR VOLUME ROOT WAS USED FOR
      PROPERTY CALCULATIONS.


小弟不知如何解决，请各位不吝赐教，万分感谢。。。。