Focus on Sustainability: Using Water as a Refrigerant

In order to implement a functioning circular economy in its entirety in an ecologically sensible way, the CO2 emissions of the processing operations must be reduced in addition to increasing the recycling of plastics and the extensive use of recycled materials.

The basic problem of the plastics processing industry is a constantly necessary cooling requirement, mostly based on energy-intensive processes in combination with refrigerants that have a high greenhouse gas potential. Some plastics manufacturers now rely on water as a natural and, above all, CO2-neutral refrigerant in their cooling and refrigeration machines. For a functioning circular economy, it is not enough to optimise the material properties of the product in terms of sustainability. Extruders, injection moulding machines or even rollers – cooling plays a major role in the processing of plastics – it is even crucial for the overall quality that there are no major temperature fluctuations.

According to the International Institute of Refrigeration, eight per cent of global emissions are caused by the refrigeration industry alone, writes Angelika Thum of Efficient Energy in the trade journal 'Plastverarbeiter'. By switching to natural refrigerants such as water, air, ammonia, propane or CO2, direct emissions could be almost completely avoided. The corresponding refrigeration technologies are available, have already been tested in industry and can now cover the entire refrigeration demand.

Water – a Natural and Unproblematic Refrigerant

Operators of refrigeration systems using water no longer have to deal with issues such as the greenhouse potential, toxicity or explosiveness of the refrigerant. From the point of view of energy efficiency, too, water has an advantage over F-gases (fluorinated greenhouse gases) because of its high heat of evaporation.

Legislation to reduce the CO2 equivalents of F-gases has led and is leading to some refrigerants being banned outright and others probably being changed several times in less than ten years. This results in bottlenecks, price increases, increased maintenance of existing plants and, in case of doubt, limited operational safety. In addition, F-gases have to be transported, stored, made available and disposed of. All these points are eliminated when using water and help companies reduce their carbon footprint.

From this point of view, the concept of 'free cooling' is also very interesting. In this free cooling system, the compressor typically used is reduced in speed or switched off completely when the outside temperature is low enough. This saves the energy required and reduces the operating costs of the refrigeration system even further.

Photo: visoot


Regardless of Whether Liquids or Bulk Solids: In Future, Measurement Will Be Possible with Just One Device

The new generation of measuring instruments follows the principle of radically simplifying level measurement with radar devices. The development to this state of the art in measurement technology was already set in motion 20 years ago and now suppliers are finally doing away with the decision between bulk solids and liquids.

Since 2016, the manufacturer Vega from Schitach has consistently relied on 80 GHz technology in its developments, which is characterised by particularly precise signal focusing, great dynamics and a high level of protection against interference. In addition, a particularly narrow signal echo makes it possible to maintain very small distances between the sensor and the surface to be measured.

With the new generation of measuring devices (here the 'Vegapuls 6x'), this property has been refined to such an extent that a distinction between liquids and bulk solids is no longer relevant. Thus, it is possible to reduce the distance between the sensor and the surface in the silos from 80 cm to 30 cm and thus (economic advantage!) to better utilise the silo volume.

Redefining the SIL Level

Plant and machinery can pose risks that are so threatening that people and the environment must not be exposed to them under any circumstances. If such a hazard exists, the existing risks must be reduced to meet the safety requirement. One measure of this is the 'Safety Integrity Level' (SIL), which makes the risk reduction quantifiable. Ultimately, however, SIL is also quite clearly a device property.

Vega's application has also taken care of this aspect. Such 80-GHZ applications must be developed differently from the ground up if the requirements for functional safety according to higher SIL are to have an effect. The new radar chip achieves failure rates that exceed previous standards by a factor of ten. This is achieved primarily through innovative self-tests in which the test signal is fed into the very front of the antenna and thus the complete measurement chain from said antenna to the sensor is taken into account. This reduces the failure rate to almost zero, as the manufacturer points out.

Advantages for the Chemical Industry

And something else could be realised: For the chemical industry, the pressure and temperature range of the devices could be noticeably extended. This is achieved by the fact that the antennas, which were previously filled with plastics, can now also be filled with ceramics, making applications with temperatures from -196°C to +450°C and pressures between -1bar and +160bar possible.

The trend is clear: the users simply decide on the basis of their application how the device is configured. And in any case as uncomplicated as possible.

Photo: arborpulchra

Failures, Costs, Interrupted Production Processes: Easily Avoidable Through Surface Cleaning

 The production of high-quality parts is indeed daily business for the plastics processing industry. In production, it is not uncommon to fall back on the moulds of the customers. It is indispensable to treat the tools provided with care, because if damages occur, the reputation of the processing company naturally suffers. But that's not all: competitive pressure is also forcing thermoplastics processors to achieve maximum efficiency and constantly rising quality standards.

During thermoplastic processing, small amounts of the polymer, additives and pigments usually remain on the surface. Over time, this leads to deposits that also affect the surface quality of the parts. This threatens an increase in rejects - and creates a clear economic risk. In fact, just a few defective parts can affect an entire batch.

If such a batch is nevertheless delivered, there is a risk of consequences such as complaints or a poorer supplier rating. And in its worst case, the customer relationship is in jeopardy. The formation of such residues is a slow and steady process that is by no means always synchronous. For example, certain polymers, additives and pigments have a greater tendency to form deposits during long production cycles, others less so. Polyamides, PVC, acetals and numerous other substances, for example, accumulate more, polyolefins leave wax and trapped pigments on cavity surfaces.

How To Proceed With Maintenance?

The question of how to proceed with maintenance is by no means trivial. The differences in quality only become apparent in the final analysis. In order to reduce the unavoidable and often considerable maintenance costs and downtimes, the regular use of mould cleaners is recommended. The advantage is that plastics processors can save a lot of money, time and waste with a small amount of material and only a few minutes for regular cleaning.

What is particularly important to look out for? Checking for weld lines, bubbles and surface defects is still comparatively simple. This can be done directly at the machine and in a timely manner. Partially blocked vents (such as vent pins) can be much more difficult to detect. But they are very important in the process, because contaminated mould parts and tools can significantly impair filling. A good indication is also when an increasing surface gloss appears on structured surfaces - but this is often difficult to detect.

Source: Laurent Saleur (Chem-Trend) in the trade journal Plastverarbeiter 9/2021

Photo: Всеволод Чуванов


Digitalisation: Adapting Mechanical Raw Material Handling To A Fast-Moving Market

Getting raw materials to the right place in the right quantity and at the right time is becoming increasingly complex and time-consuming. The turnover on the market is becoming faster and faster – and so a traditional process such as raw material handling must be significantly accelerated for this market through accompanying digitalisation. New challenges posed by new markets, a growing interest in recycling solutions or the rapid progress of electromobility require clear changes.

''The dust-free handling of raw materials for battery masses is extremely challenging, ' comments CTO Klaus Kilian of AZO in Osterburken, Germany, one such example. In future, not only product protection but also operator safety will have to be taken into account. And, of course, there are the special properties of such raw materials – very high requirements can hardly be solved with traditional mechanical processes, or they become very expensive and thus cannot be marketed well.

Data Analysis And Intelligent Tools For Future-Proof Business

A good example is powders that are used in 3D printing. Up-scaling, which is common in the industry, becomes down-scaling here. Some things just don't work anymore when the systems get smaller. Handling is really challenging: operator protection is extremely high, and at the same time the product itself must be protected from environmental influences, as it is sometimes very reactive. Digitally supported handling makes a decisive difference here. Clear data analytics will play an increasingly important role in the future. In the future, data will have to be collected and analysed at various levels so that companies can react even more quickly and in a more targeted manner.

Thinking consistently ahead, the systems will also have to become easier to operate, and the same applies to maintenance: "The goal must be that routine maintenance no longer takes place every two years, but that the system signals itself when a component threatens to fail," say the specialists from AZU.

The ubiquitous shortage of skilled workers also plays a significant role in this new, digital raw material handling. At the moment, there are still plant employees with 15 to 20 years of professional experience who can sense or hear the slightest discrepancies in a plant. Although not everything will be replaced by sensors, digital tools will increasingly be used to replace such specialists.

Raw material automation and logistics still include many mechanical process engineering procedures, but these must be combined with intelligent digital tools to be able to act in a future-proof manner for the benefit of the customer.

Photo: industrieblick


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