Method and device for adjusting the cooling and energy recovery of a steel strip in an annealing or galvanization phase

A method for adjusting cooling needed for a forced cooling of a steel strip running continuously in a plant adapted for continuous annealing or continuous hot-dip galvanization, cooling energy is given up to heated water by the steel strip and then removed by evaporation of the heated water at a pressure below atmospheric pressure and finally returned by condensation at a higher temperature following thermomechanical compression by a venturi device supplied with vapor at a pressure higher than atmospheric pressure, which comprises the steps of:

• collecting the heated water heated by the steel strip in an exchange unit at a first pressure close to the atmospheric pressure and a first temperature lower than an evaporation temperature of the heated water at the first pressure;
• introducing the heated water from the exchange unit in a form of a jet into a sealed enclosure of a cooling unit fitted with at least one ejector being a venturi device, the ejector also being supplied with water vapor at an incoming pressure higher than the atmospheric pressure, the ejector providing a partial vacuum in the sealed enclosure corresponding to a second pressure lower than the evaporation pressure of the water at the first temperature;
• and
• recovering cooled water at an outlet of the sealed enclosure at a second temperature corresponding to the evaporation temperature of the water at the second pressure to be returned to the exchange unit.