The DTB crystallizer belongs to the slurry circulation type crystallizer. The crystallizer is equipped with a guide tube and a push type stirring blade, and the material circulates in a certain direction from bottom to top under the pushing of the stirring, and then repeats the cycle from top to bottom. The newly added hot material is sent from the mixing point and quickly dispersed in the mixing system. The material moves upward to the liquid surface and is cooled by vacuum flash evaporation, forming supersaturation in the solution. During the downward mixing process of the material, supersaturation is eliminated, and the crystals in the solution gradually grow.