Method for managing retort over-pressure during pressure cooling

A method for pressurizing during cool down an interior of a batch retort vessel and with a final cooling pressure of P.sub.fc, which has been hated by steam to a heating temperature and a heating pressure P.sub.h, comprising the steps of:

• specifying an initial cooling temperature T.sub.ic ;
• specifying a final cooling temperature T.sub.fc ;
• providing a non-condensable gas to the interior of the vessel, causing the pressure inside the vessel to be elevated to an initial cooling pressure P.sub.ic ;
• continuously providing the non-condensable gas to the interior of the vessel to maintain the pressure inside the vessel at the initial cooling pressure;
• introducing a flow of coolant into the vessel;
• draining the coolant from the vessel;
• measuring the temperature T.sub.p of the coolant drained from the vessel;
• and
• regulating the pressure in the vessel P.sub.y, so that P.sub.y =P.sub.fc +F(T.sub.p,T.sub.fc,T.sub.ic).times.(P.sub.ic -P.sub.fc) when the temperature T.sub.p of the coolant drained from the vessel is less than or equal to the initial cooling temperature T.sub.ic and wherein F(T.sub.p, T.sub.fc, T.sub.ic) is a function of T.sub.p, T.sub.fc, and T.sub.ic and wherein if T.sub.fc .ltoreq.T.sub.p .ltoreq.T.sub.ic then 0.ltoreq.F(T.sub.p,T.sub.fc,t.sub.ic).ltoreq.1 wherein F(T.sub.p,T.sub.fc,T.sub.ic)=[(T.sub.p -T.sub.fc)/(T.sub.ic -T.sub.fc)].sup.2.