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Twin screw extrusion Wenger revolutionises twin screw extrusion with unique models dedicated to pet food and aqua feeds
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by Adrian Martinez-Kawas, PhD, Wenger Manufacturing
raditional twin-screw extrusion design has served its purpose as the pet food and aqua feed industries developed. Yet both industries now stand at a tipping point where new trends are pushing the traditional systems beyond their limit. Flexibility is key and what the new generation Wenger twin screw extrusion systems are built on. The Thermal Twin® extrusion system is tailored for pet food manufacturers, so they can develop a wider range of products using an extensive choice of ingredients while preserving ingredient and product identity. The Aquaflex® extrusion system is tailored for aquatic feed manufacturers to maximise their investment by giving them the capability to manufacture a wide range of products such as floating, sinking, shrimp, and micro feeds in different product sizes while utilising a broad ingredient selection. This flexibility is possible given these systems are engineered with a specialised screw profile design to deliver higher volumetric capacity and the capability to operate using a wide range of thermal and mechanical energy cooking conditions. Thermal and mechanical energy are the main energy
42 | November 2019 - Milling and Grain
Table 1. Energy input and operating cost comparison between Wenger single screw, twin screw and thermal twin screw extrusion systems Extrusion Systems
Single Screw
Twin Screw
Thermal Twin Screw
49.7
65.6
154.7
37
60
16
Total Energy (kWhr/mt)
86.7
125.6
170.7
Energy Cost ($/mt)
5.3
8.07
6.22
Wear Cost ($/mt)
2.1
3.41
0.91
Total Cost ($/mt)
7.4
11.48
7.13
Specific Thermal Energy (STE, kWhr/mt) Specific Mechanical Energy (SME, kWhr/mt)
Table 2. Percent of Coefficient of Variation of Moisture Content and Cook Using Different Steam Conditioner Designs Steam Conditioner Design
Coefficient of Variation of Moisture Content (%)
Cook (%)
HIP – High Intensity Preconditioner
2.65
30
DDC – Differential Diameter Cylinder
4.96
25.9
DC – Double Cylinder
6.66
20.4
SC – Single Cylinder
9.36
15.7