Method and system for stack heat recovery

A method of recovering heat from an exhaust stream during a manufacturing process in a plant comprising:

• providing a heat stack recovery system including a condensing heat exchanger, the condensing heat exchanger having a first side with cold recirculation water and a second side;
• passing an exhaust stream of vapors and having a temperature of 500 degrees F. or less into the heat exchanger through the second side;
• transferring heat from the exhaust stream to the first side of the condensing heat exchanger and cooling the vapors to the dew point to cause condensation;
• collecting the condensation in a condensate tank;
• recovering condensate water from the exhaust stream of from 20% to 75%;
• sending the cooled exhaust to a discharge stack;
• transferring the condensate to a flash tank to adjust a volume of the recirculation water routed thereto;
• inputting a source of external make-up water into the flash tank, as needed,
• wherein the amount of external make-up water required in the flash tank is reduced by the amount of condensate water recovered by the heat stack recovery system.