which fits continuous cooking uses an expansion of about 1 u00b0 c to about 5 u00b0 c for spent liquor led from the digester in an arrangement analogous to that of fig2 c these systems will efficiently remove turpentine and other gases through conduit 45 with minimum loss of energy thereby the energy efficiency of the continuous digester system is not affected the liquor conducted through conduit 41 is further depressurized in flash tanks following tank 43 a clear difference of the invention compared to prior art flashing in e g continuous cooking is that the temperature difference and pressure drop in flashing according to the present invention are significantly lower typical pressure drops in primary flash tanks of continuous digesters are over about 2 3 bar corresponding to a temperature difference of over about 25 30 u00b0 c in prior art flashing of spent liquors in cooking systems the main target is energy saving by using the resulting flash steam to heat the charged chip material we have surprisingly found that only a low degree of expansion is needed to release turpentine from the spent liquor the advantage of using a lower degree of expansion is that less energy is lost to turpentine recovery and lower condensate amounts are produced this fits the heat recovery principle of liquor displacement batch cooking systems where hot black liquor is recovered at the end of cooking and its energy is reused 1 as a direct heating medium to be pumped into the digester during a subsequent.