Extruder(挤出机).ppt

Extruder Heat Generation Advantages of Extrusion Process * EXTRUDER Motor Water pump Hopper Feeder Cutter Feeding barrel Heating system Cooling system Die Clextral EVOLUM 53 Extruder Extruder development in the food industry Mid-1930s Single screw continuous pasta press Oil extraction Pet foods 1960s RTE cereals 1980s Aquatic feeds In 1998 Retail value of extruded products: $3.62 billion or 3.7 million tons of production Extruder Classification Pasta 30 30-52 32 Pasta press Cereal pellets Half-product snacks 40 65-80 25 High-pressure forming extruder Puffed snacks 300 170-200 11-16 Low-shear cooking extruder Modified starch 350-500 120-180 15-20 High-shear cooking extruder Puffed snacks RTE cereals 200-500 80-200 11-35 Twin-screw cooking extruder Typical Products Screw Speed (rpm) Product Temperature (oC) Feed Moisture (%) Screw(s) Die Basic extruder components SCREWS and SHAFTS Conical screw caps Shaft Screw elements 1/2 P - 6 units Twin-flight 3/4 P - 9 units Twin-flight 3/4 P - 9 units Single-flight 1/2 P - 9 units Twin-flight 1/1 P - 9 units Twin-flight 3/4 P - 6 units Twin-flight Cone-screw Washer 1/2 P -cut 6 units Twin-flight Paddles 0.75 units Paddles 1 unit 3/4 P 4.5 units Twin-flight 3/4 P - cone 9 units 1/2 P - Rev 1.5 units 1/2 P 0.75 units 3/4 P - cone 9 units - cut Shaft Collar 3 units Disks 0.75 units 3/4 P - cut 9 units Twin-flight 1/2 P - Rev 0.75 units 1/2 P - Rev 6 units Twin-flight Elements for generating screw profiles and pressures D= screw diameter h= channel depth t= pitch N= screw speed e= axial flight tip thickness n= number of screw threads, d= clearance between flight tips and barrel f= screw helix angle (a function of diameter and pitch) Adaptability Product variety Energy efficiency Low cost Unique products Increased throughput Product quality Minimal waste Minimum labor Combine several steps in conventional process *