Four typical Systems of Single Screw Extruder
The Single Screw Extruder as claimed in four systems including Solids Feeding System, Solids Feeding System, High Speed Mixer / Preconditioner, Fluid Metering Systems, The Extruder System.This system is designed to accurately meter the pre-blended Dry Feed components of the formulation (commonly the Cereal Components) into the next stage of the process at a steady and reproducible rate. The system may incorporate either Volumetric or Gravimetric (or Loss-in-Weight) technology, depending upon the twin screw extruder degree of control sheet production extruder (or accuracy of dispense) sought.
(A) Solids Feeding System
The most important operational characteristics of these systems are the Degree of Mixing, the Mean Residence Time and the Residence Time Distribution.In the case of a High Speed Mixer (HSM) the Residence Time is typically very short(with t < 20 seconds), thus little cooking actually occurs.In the more recent development of this technolog.
(B) High Speed Mixer / Preconditioner
This stage is commonly employed on most Single Screw Extruder installations although it is not as common in many existing Twin Screw Extruder installations. This device is used to promote the uniform Hydration (or “wetting”) of the Dry Feed and also to initiate the Cooking Process (in those applications used.
In some applications, such as Pasta Manufacture, the system may be fitted with a Vacuum Facility to minimize the Air Entrapment within the finished product.The material discharged from the Preconditioner system should consist of a well hydrated (and uniformly heated, if Steam Injection is applied), however, free-flowing powder, that will readily feed into the Extruder Barrel.
(C) Fluid Metering Systems
Depending upon the product being manufactured, a number of such systems may be required to incorporate the various Additional Fluid Components into the Extruder. Some of the more common ingredients used include Water, Dye Solutions, Flavours, Humectants, Oil (or Lipids), a Distribution Manifold. In some applications the Steam may be added directly into the Extruder Barrel; although this will require a specific Screw Profile Design to ensure that “blow-backs” do not occur.
(D) The Extruder System
The Extruder is the heart of the process. Thus, the selection of the “correct” extruder improves the chances of having a successful extrusion operation. Unfortunately, poor selection of this equipment or more specifically twin screw extruder the correct Screw Profile Single Screw Extruder may result in a marginal or sub-optimal process