Solvent recovery process during continuous audio- or video-tape mfr.

摘要

The assembly to recover solvents, during mfg. of continuous materials such as audio and video tape, returns major portion of the inert gas and especially nitrogen from the solvent separator (26) through a channel (100) back to the heat exchanger (20). It is heated against the gas flow from the drier (14) and then returned to the drier (14). A smaller portion of the gas is passed back from the solvent separator (26) to the deep temp. section (12) to be cleared of solvent, and to be at least partially extended with part chambers of the vaporised inert gas, especially nitrogen. It is then passed to the lock (16,18) at the drier (14) to give a positive gas inflow and outflow. A control, pref. valves (102a,100a), is behind the solvent separator (26) to determine the major and minor portions of the gas flow. The deep temp. section (12) has an initial heat exchanger for the liquid nitrogen to be heated for vaporising with a cold carrier to give the required enthalpy for the vaporised nitrogen. A second heat exchanger gives the reheating of the cold carrier for the required enthalpy of the solvent-charged inert nitrogen gas gives cooling to a given temp. and the vapour. A carrier circuit recirculates at the cold carrier between the two heat exchangers.