Method and device for recycling and purifying water vapor from coal drying process

A method for recycling and purifying water vapor from a coal drying process, comprising:

• a step of temperature-lowering and dehumidifying, which comprises
• transferring an exhaust gas with water vapor from a coal drying process into a cooling tube, in which the exhaust gas is temperature-lowered by contacting a first part of a first condensed water from a bottom of a condensing tower;
• and
• transferring the temperature-lowered exhaust gas into the bottom of the condensing tower, and transferring a second condensed water from a flash distillation tank into the top of the condensing tower, so that the exhaust gas and the second condensed water from the flash distillation tank contact each other in a vapor-liquid reverse manner in the condensing tower to condense the water vapor in the exhaust gas into water, which is accumulated in the bottom of the condensing tower;
• a step of flash distillation stripping, which comprises transferring a second part of the first condensed water accumulated in the bottom of the condensing tower into the flash distillation tank, and performing a vacuum flash distillation stripping therein to obtain the second condensed water and a water vapor, wherein the obtained second condensed water is transferred into the condensing tower for the step of temperature-lowering and dehumidifying, and the obtained water vapor is transferred into a demisting washer and demisted therein and then transferred into a vapor condenser;
• and
• a step of vacuum condensing, which comprises performing a vacuum condensing in the vapor condenser to the water vapor from the step of flash distillation stripping to obtain a third condensed water, which is then transferred into a recycled water tank.