Seven-effect vacuum salt production process

The invention relates to a seven-effect vacuum salt production process, which comprises the following steps that live steam enters a steam jet type heat pump (if the pressure of the live steam is not high, the heat pump is not arranged), and part of I-effect secondary steam is extracted to be subjected to temperature and pressure reduction and then enters an I-effect heating chamber; material liquid in the I-effect evaporation tank is subjected to indirect heat exchange with steam in the heating chamber through power of a circulating pump and then is subjected to boiling flash evaporation in the evaporation chamber, and the flash evaporation steam enters the II-effect heating chamber through a secondary steam pipe to serve as a II-effect heat source. The condensate water of each effect returns to the balance barrel of each effect through the condensate water coil pipe, the dry condensate water is subjected to flash evaporation in the I-effect condensate water balance barrel, the condensate water of each previ