Difference between single-screw and twin-screw expanders
Twin-screw extruder: Generally used in the production of high value-added aquatic and pet feeds, such as eel, snapper and juvenile feeds, because the price of these products in the market is enough to pay back the cost of manufacturing products with twin-screw technology; in addition, some special aquatic feeds such as particulate aquatic feeds (diameter of 0.8~1.5mm), high-fat aquatic feeds and feeds with small production volume but with frequently changing formulas Twin-screw extruders are also required for production.
It is necessary to clarify that the above difference is not certain, for example, we recommend the use of twin-screw production of aquatic feed, but now there are many companies with a single-screw production of aquatic feed. There is a difference between the two for aqua feed. In short, twin screw has the following advantages compared with single screw:
① The adaptability of raw materials is wider, it can adapt to the processing of high viscosity, low viscosity, high oil content, high moisture or viscous, oily, very wet raw materials and other raw materials that will slip in the single screw (SSE).
② Less restriction on the particle size of raw materials, can be adapted to the processing of raw materials from micro-powder to coarse powder particles and the processing of raw materials with particle sizes outside the specific range of single-screw processing.
③Material flow in the barrel is more uniform, and steam and water can be added to make the product achieve the desired effect.
(4) The inner and outer quality of the product is better, and it can achieve very good homogeneous state and make the molecular structure of the material arranged uniformly, and the surface is smooth in the process of extruding out of the mold, and the product particles have high degree of neatness and good uniformity.
⑤ Better aging and homogenization effect, usually the degree of starch aging can reach more than 95%, so that the processed aquafeed can keep stable in water and the nutrients of the product will not be lost, and it is easy to be digested and absorbed.
(6) Higher output under the same power. The good mixing performance makes the heat of the material get uniform in time, accelerates the maturing degree of the material, reduces the fluctuation of the material temperature, and improves the output of the extruded products.
(7) The diversity and adaptability of products are wider, and it can process micro-particle aquatic feed and high oil formula, high moisture, high viscosity products and multi-color, sandwich class, special shape products.
⑧ process operation is more simple, according to the processing product demand adjustment of spindle speed, due to the self-cleaning characteristics, clean up is very convenient, every time after processing without disassembling equipment.
9 wear parts wear lighter. Usually a misconception that the single screw wear less, in fact, in the twin-screw extrusion process due to stable material transportation and material flow characteristics, determines the material on the screw and barrel inner sleeve wear and tear than the single screw is small, despite the number of screws out of a set, but the cost of spare parts is still lower than the single screw.
⑩Lower production cost, due to the twin-screw model has good operational stability, in the feed processing process, less start-up costs, less water and gas waste, less labor cost, high heat transfer efficiency, high yield, high kilowatt-hour production index, plus the cost of spare parts is also low, the final cost of production compared to the single-screw is still much lower.
