A multistage distillation system, comprising:
- a plurality of stages Si, where i=1, . . . n, wherein each stage Si works in a higher pressure and temperature range (Δ Pi, Δ Ti) than its ensuing stage Si+1 during operation, wherein each stage Si includes a pressure-tight vessel Vi that contains an evaporator Ei and a condenser Ci, wherein each evaporator Ei includes a spray inlet for introducing and spraying added liquid into the evaporator Ei and a lower outlet for letting out liquid from the evaporator Ei and defines a steam space between the spray inlet and the lower outlet, wherein each condenser Ci includes a spray inlet for introducing and spraying added liquid into condenser Ci and a lower outlet for letting out liquid from the condenser Ci and defines a steam space between the spray inlet and the lower outlet;
- a pressure-tight steam pipe disposed within each vessel Vi and connecting the steam space of each evaporator Ei with the steam space of each condenser Ci, the pressure-tight steam pipe being configured with a cross section large enough that the pressure Pi in the steam space between the evaporator Ei and the condenser Ci of each stage Si can always achieve equilibrium;
- an evaporator circuit configured with the outlet of each evaporator Ei connected via a respective pressure-tight liquid line with the spray inlet of the next evaporator Ei+1 except that the outlet of the last evaporator En is connected with the spray inlet of the first evaporator E1;
- and
- a condenser circuit configured with the outlet of each condenser Ci connected via a respective pressure-tight liquid line with the spray inlet of the preceding condenser Ci−1 except that the outlet of the first condenser C1 is connected with the spray inlet of the last condenser On;
- and
- a pressure-tight steam line having a first end connected with one of the pressure-tight liquid lines between the condenser Ci and the condenser Ci−1 or with the pressure-tight liquid line between the evaporators En and E1, and the pressure-tight steam line having a second end connected with a steam space having a higher pressure P during operation than the pressure in the pressure-tight liquid line to which the first end of the pressure-tight steam line is connected, so as to pressurize the liquid with a higher pressure and convey the liquid.