Using BBE‘s WFC for pre-cleaning PET and PA 6 filters enables manufacturers to renounce solvents. TEG and similar solvents are toxic, highly flammable, harmful to the environment and costly in terms of purchase and disposal. WFC – using only steam – is eco-friendly, cost-saving and less dangerous for users.
The cleaning effect of White Filter Cleaning is based on a combination of both hydrolysis and gas flow dynamics. Super-heated steam flows through the polluted filter elements in reverse direction (compared to regular polymer flow). After having drained out the melt (PET or PA 6) with the support of gravity and nitrogen pressure as much as possible, the remaining melt inside the filter insert is pushed out by super-heated steam. The steam is injected via ports into the cleaning vessel until a pre-set pressure (up to 8 bar) is reached.
During this fill-up time, the steam reduces the viscosity of the melt inside the filter insert by means of a hydrolysis degradation. After that, the pressure is released by means of a sudden opening of a decompression valve (gas flow dynamics effect). This cycle of hydrolysis and decompression is repeated multiple times, each cycle removing some polymer from the filter into a waste collector. There, condensed water and pollution are separated for an easy disposal of both. After having removed the polymer using WFC, the filter elements can be transferred to regular subsequent final cleaning steps, such as high-pressure water jet, alkali bath and ultrasonic treatment. This pre-cleaning method is as effective as to substitute any other common pre-cleaning methods, such as cleaning using solvents.
BB Engineering recently demonstrated the effectiveness of WFC in the case of filters from BO-PET lines equipped with discs and at large candle-type-filters from a PA6 chips production system. Typical methods for evaluating the cleaning effect are to compare the bubble point values and the weight per filter element in new condition versus values after cleaning.
According to BBE, using WFC for pre-cleaning PET and PA 6 filters enables manufacturers to renounce solvents. TEG and similar solvents are toxic, highly flammable, harmful to the environment and costly in terms of purchase and disposal. WFT – using only steam – is eco-friendly, cost-saving and less dangerous for users.
Key technology features:
- Steam supply unit: Here, the steam for the pre-cleaning process is generated and super-heated. Also, the process controls are located in the steam supply unit.
- Cleaning station: The whole filter insert, meaning vessel with candles/discs, is taken from the production and inserted into the cleaning station right away without any cooling, pre-heating or other preparations. Step 1 is draining the liquid melt. Step 2 is the repeated cycle of hydrolysis and gas flow dynamics.
- Decompression valve: A ball valve between the cleaning station and the waste collector excites the gas flow dynamics effect of the cleaning cycle by relaxing the beforehand built-up pressure in the cleaning chamber and moving out steam and melt rests.
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