The issue of plastic pollution can appear to be in the news almost constantly at the moment – and with good reason. According to reports, there is now no corner of the globe that is not touched by plastic pollution, and plastics may have infiltrated our food chain. Against this background, it is unsurprising that plastics manufacturers find themselves heavily scrutinised and must assess their production process to prevent their products from escaping into the environment.
Around 2.5 million tonnes of plastic are produced in the UK every year, often starting life as tiny pellets referred to as 'nurdles'. The product is usually transported in this raw state and stockpiled before processing. Raw plastic is also held in powdered form, depending on requirements later in the production process. Additionally, powdered materials like mica, clay, or calcium carbonate are also held in bulk as they are utilised in the manufacturing process.
The properties of plastics mean that they can be challenging to accurately and reliably measure. It is very light, and plastic is an insulating material with a low dielectric constant - as low as 2-3 Dk. Plastics are poorly reflective, meaning non-contact technologies like ultrasonics have struggled to detect them reliably. Mechanical non-contact-based systems like plumb-bob, on the other hand, are prone to wearing out over time. Unreliable level control means an increased risk of overfilling. Besides this, over-pressurisation of silos containing plastic powders or other ingredients will not only result in product loss but may have additional safety implications as well (refer to the 'What is Silo Protection' page in the 'About Us' section).
These are two related, but distinct issues that the industry needs to address. Given that older control methods have shown themselves to be ineffective, what is required are modern, proven solutions. Having provided comprehensive level measurement and silo protection systems to a wide range of industries over the last three decades, Hycontrol is qualified to offer advice to the plastics industry.
Plastic beads are lightweight and poorly reflective, which has always made them difficult to accurately monitor. Hycontrol's RD Series radar utilises the 80 GHz frequency to overcome this long-standing problem. The higher frequencies allow for a tighter pulse beam and improved focusing of the emitted signal. The high FMCW radar signal dynamics provide hugely-improved results on poorly-reflective products with uneven surfaces, like plastics. A small beam angle makes it ideal for continuous, non-contact level measurement in high, narrow silos up to 100 m / 328 ft. Extensive trials of this new technology on plastics and other 'difficult' materials have yielded excellent results. 80 GHz radar is now Hycontrol's recommended solution for plastics level.
With regards to powder silo control, the plastics industry may benefit from looking at the steps taken in the aggregate industry, which have helped to improve standards significantly. Essential safety guidance published by the Mineral Products Association calls for self-cleaning filtration systems, comprehensive pressure and level monitoring/warning systems, and a calibrated pressure relief valve. Testing of all of these components must take place before the delivery begins. While there are several markedly different silo protection systems on the market at present, it is worth noting that Hycontrol is the only manufacturer whose systems not only meet but exceed MPA guidance. Hycontrol's SHIELD SPS is the most advanced such system in the world.
Contact Hycontrol to discuss your plastics application.
Plastic Waste Shredder Control with 80 GHz Radar Application - Recycling Industry
Optimum Positioning of Level Sensors for the Measurement of Silo Contents - White Paper
Preventing Plastic Pollution Through Effective Control - White Paper
RD Series Radar for Plastic Pellets - Application Datasheet
Silo Protection for Plastic Powders - Application Datasheet
