Production process of environment-friendly denim fabric and production line thereof

A production line of a denim fabric, comprising:

• a spinning unit having a spinning frame, a winding machine and a false twisting device, wherein the false twisting device is located between a front roller outlet and a yarn guide hook of the spinning frame and is for excessive pre-torsion of yarn slivers in an axial direction and generating twists which are the same in quantity but different in twisting direction on the yarn slivers;
• a dyeing unit configured to perform adsorption of glucose-containing sulfur dyestuff on yarns with the twists in padding liquor of 60-90° C. and then perform color fixation;
• a loom unit configured to perform a process of weaving to produce a fabric;
• and
• a liquid ammonia finishing unit consisting of a fabric mercerizing device, an ammonia removal device, an ammonia recycling device and a controller, wherein the fabric mercerizing device is configured to enable fibers of the fabric to swell to achieve a mercerizing effect under certain temperature and tension and under dipping and action of ammonia;
• the ammonia removal device is configured to evaporate residual ammonia in the fabric;
• the ammonia recycling device is configured to collect evaporated ammonia and feed the evaporated ammonia back to the fabric mercerizing device for continuous use after the evaporated ammonia is cooled down and compressed;
• the controller is configured to control various parameters of the ammonia recycling device.