The twin screw press, also called double spiral squeezer, is applied for black liquor extraction and thickening and de-watering of wood pulp, bamboo pulp, reed pulp, cotton stalk pulp, wheat straw pulp and waste paper pulp etc. It adopts kneading and pressing by double screws to thicken and dehydrate. As a new generation of eco-friendly and energy-saving dewatering equipment, this screw extruder is equipped with a fully-closed protective cover which eliminates environmental effects to worksite. Its graded compression ratio promotes equipment stability and operation efficiency.