|CO2 saving processes in Extrusion plants -
In-Line Recycling of PROCESS CONTROL
In times of huge increases in energy costs everyone looks for saving each possible kilowatt-hour. Looking ahead to the future, with worldwide energy consumption increasing, further price rises can be expected making the situation even more critical.
Plastic extrusion companies in particular have substantial electricity running costs
One method of recycling production-caused film scrap is by “repelletizing”. One advantage of a repelletizing line is that it produces an easy to handle bulk material (granulate). However, a negative aspect is that this process puts a large amount of thermal energy into the material. This can cause a chemical degeneration of the material resulting in a change of the melt-flow index (MFI). In many cases a re-stabilisation is required by the use of expensive additives. Another disadvantage is that this procedure devours enormous amounts of energy.
A typical repelletizing system consumes in total, for the whole recycling process (cutting, melting, granulating, cooling, transportation), approximately 1.75 kWh per kg of the plastic that is recycled. An example of the energy used in a typical situation is given below: With a total throughput of 900 kg/h, a recycling rate of 15 % and a machine running time of 24 h a day, 5 days a week and 48 weeks a year then approx. 1.360.000 kWh per year will be consumed. In Germany, for example, production of electricity creates CO2 emissions of approx. 130 g CO2 per kWh. Which means the electricity used in the repelletizing process shown above will produce approx. 177 tons of CO2 per year!!!
The asr system itself is very uncomplicated in handling and start-up. It usually consists of an edge-trim transport system using a venturi system, a film scrap grinder and a refeed machine. The refeed machine, which is directly mounted on the extruder, compresses the ground material and feeds it to the extruder. By compressing a 5- to 7-times higher bulk density is achieved compared to loose fluff. Thereby pumping of the extruder is avoided.
To find out more about the asr system
For ENGLISH CLICK HERE For DEUTSCH CLICK HERE