Environmentally Friendly Cleaning Of Pipe Systems During Product Change

A major cost factor in industrial plants with frequent product changes is the complete cleaning of pipes and piping systems. Everything must be clean before the new product can flow through the transport systems. Apart from the fact that short interruptions are preferable in order to minimise production downtime, environmentally-friendly solutions are also increasingly in demand today.

In the case of water-based products, such as aqueous solutions, emulsions or dispersions, a water flush is often used to remove any remaining residues of the previously conveyed product. Depending on the purity requirements, more or less large quantities of wastewater are produced, which must then be disposed of. The costs for this often make up a large part of the operating expenses. In addition, industrial plants often contain critical substances that have to be collected separately and disposed of at great expense. Therefore, it is obvious to design the rinsing, the cleaning highly effective in order to produce as little wastewater as possible.

Often a pig is used, a cleaning or inspection device that fills the pipe cross-section and either simply travels through the pipe with the product flow (usually with oil) or has to be pressed through the pipe by extra pressure (water or compressed air). Problems with this method are geometric changes in the pipeline, fittings with tight radii or pumps, butterfly valves and backflow preventers. Such systems cannot be cleaned at all and may even have to be removed. In addition, more or less thick product films can remain on the inner surfaces of the pipeline, especially in product lines for dispersions or viscous solutions.

New Flexible Cleaning Method Works Efficiently And Sustainably

Established processes require a high degree of integration effort or generate large amounts of wastewater and thus disposal costs. A new system developed by ‘Hammann Engineering’ works efficiently and thoroughly with little water, produces little waste water and is easy to integrate into existing piping systems. The so-called Comprex process quickly pays for itself through saved disposal costs.

The cleaning method is based on the controlled, impulse-like addition of compressed air into a pipeline partially filled with water. This accelerates water blocks in the pipeline to high speeds of up to 20 m/s. This mobilises and discharges impurities, deposits or, in the case of product pipes, also residues of the transported product. In contrast to conventional water flushing, however, Comprex cleaning produces up to ten times less wastewater, according to the developer.

In initial tests under real conditions at BASF, it was shown that the amount of product-polluted wastewater produced can be reduced by an average of 70%. Last but not least, the operator saves considerable disposal costs every year and reduces the C02 emissions for incinerating the wastewater. This represents an important contribution towards sustainability.

 Source: Dr Till Schmidberger, Process Manager, BASF; Hans-Gerd Hammann, Managing Director, Hammann Engineering (in ‘Chemie Technik’, July 2019)

New Variable Test Method For Home And Contract Floor Coverings

Textile floor coverings are classified into areas of application by mechanically producing changes in the appearance of samples in the laboratory. However, there is no test method for producing changes in the appearance of rigid textile floor coverings and thus simulating wear behaviour in practice. A new variable test method is likely to change this situation permanently. A change in the associated EU and DIN standards is also being discussed.

Normally, these tests/classifications use the subjectively assessed strength of the change in appearance to decide whether the floor coverings are suitable for home or contract use, for weak or heavy-duty. For this procedure, samples are fixed in a drum wall. However, the procedure has not been adapted for a long time – the last adjustment from practical stress to a simulation in the laboratory was carried out in 1984 in a research project of the TFI - Institute for Floor Systems at the RWTH Aachen University. Since then, however, the product range for floor coverings has been completely renewed.

With broad support from the flooring industry in Belgium and Germany, a variable test method – the so-called FOCuS method – has now been developed. It also enables the testing and classification of non-textile floor coverings. Up-to-date knowledge of movement mechanisms and forces of the human gait play a decisive role in this.

A New Test Method According To DIN And EU Standards?

For the new development, more than 30 textile floor coverings were provided by the participating companies, representing the current manufacturing spectrum in Europe. The test method that is most comparable to the human gait is the LissonTretradprüfung. However, this test is unsuitable for the subjective visual assessment of the change in appearance, as the assessable area is too small for the often coarsely structured and patterned floor coverings.

The current approach to the newly installed test tracks differs in essential conditions from the conventionally used methods such as frequency of use, lighting and dirt ingress. In addition to regular maintenance cleaning, not only were subjective assessments and colour measurements carried out on a regular basis, but also the state of wear was documented by scanning.

For the development of the new test method, various concepts were developed on the basis of the method review and human gait, and the current parameters of the "FOCuS" test method were worked out. In addition to the rubber stoppers of the "Vettermann drum test" and the soles of the treadmill test, metal abrasion bodies were used as wear bodies due to their better wear properties. The type of changes in appearance achieved with this method is comparable to the results in the hexapod test and in practice.

In addition, the results of the new test method were discussed in workshops with the members of the project-accompanying committee.  Overall, the new test method was considered to be very forward-looking. The findings gained during the project period in comparison to previous practice should therefore also be discussed in the relevant standardisation committees at German and European level.

A report on this topic was published in the 2/2019 edition of melliand Textilberichte, the authors were

  • Sophia Gelderblom, Bayram Aslan; TFI - Institute for Soil Systems at RWTH Aachen University, Aachen
  • Jo Wynendaele; Centexbel, Gent/Belgium
  • Thorsten Knierim, Testing and Research Institute Pirmasens e.V. (PFI), Pirmasens
  • Didier Van Daele; Ghent University, Ghent/Belgium

CO2 Footprint Of Natural Fibres In Bio-Composite Materials

Natural fibres are becoming more and more important in our everyday lives and are experiencing an impressive renaissance as insulating materials and bio-composites in the automotive sector. In view of the social and economic challenges of the 21st century, it is important to analyse their environmental impact and ultimately ensure the sustainability of this revival. In fact, over the last twenty years, more and more natural fibres have been used in composites, especially in the automotive sector and more generally as insulating materials in other sectors.

Bio-composites consist of a polymer and natural fibres, the latter of which guarantee stability. Bio-composites with natural fibres can have similar functionality to other composites and are comparable to many end products.

The trend has been emerging for years: In 2012, 30,000 tonnes of natural fibres were used in the European automotive industry, mainly in moulded parts, an increase of around 19,000 tonnes of natural fibres in 2005. Current analyses from 2019 also clearly confirm this trend. When using such materials, it is important not only to consider their service life but also to compare it with the CO2 footprint.

The natural fibres normally used are hemp, flax, jute and kenaf. Results from 2015 show that the CO2 footprint of all four fibres is significantly lower than that of conventional glass and mineral fibres. Besides, researchers at the Nova Institute in Hürth have found that the CO2 footprints of the various natural fibres are very similar.

Initially Outstanding Comparative Values For Natural Fibres

The values are indeed impressively positive: the production of one tonne of glass fibres means a CO2 footprint of about 1.7 to 2.2 tonnes of CO2, while natural fibres only have a CO2 footprint of about 0.5 to 0.7 tonnes of CO2 per tonne of natural fibre (excluding transport to the customer). This is only one-third of the CO2 footprint of glass fibres. Even if the initial advantage in further processing decreases, natural fibre composites have a 20 to 50 per cent lower footprint compared to glass fibre composites.

When transporting the various natural fibres, carbon dioxide emissions to the factory gate of a European nonwoven manufacturer in the automotive or insulation sector amount to around 750 kg CO2 per tonne of natural fibre for all four natural fibres. Due to manual processing, jute and kenaf have lower emissions during cultivation, harvesting and decontamination, but long transport to Europe compensates for this advantage.

Is The CO2 Footprint The Right Measure?

Although the CO2 footprint is in itself a very useful tool for assessing the climate impact of products, a comprehensive ecological assessment needs to consider other environmental categories, according to Nova Institute researchers. Only the consideration of greenhouse gas emissions can lead to insufficient product testing and recommendations for action, especially if other environmental impacts have not been considered at all. One task of further studies is therefore to consider other impact categories. Sustainability also includes social and economic aspects. Since natural fibres are used in many industries, certification is a suitable instrument for demonstrating sustainability.

Antimony Oxide As Flame Retardant – Efficient But Also Dangerous?

Flame-retardant coated fabrics typically contain flame retardants in the coating. The following applies: The thinner the fabric and the coating, the more efficient flame retardant finishes are required. Antimony oxide is a so-called synergist which, in combination with halogen-containing flame retardants in plastics, is a very efficient flame retardant. Specks of dust of antimony oxide that can enter the body via the lungs are generally classified as carcinogenic.

Therefore, investigations are currently being carried out to determine whether coated textiles equipped with antimony oxide can pose a health hazard, reports Sebastian Eibl of the ‘Wehrwissenschaftliches Institut für Werk- und Betriebsstoffe’ in Erding.

The special aspect here is the fact that a harmful effect on health is not known by an absorption through the skin. This raises the question of whether a health hazard from antimony oxide is possible at all if it is present as a flame retardant embedded in the material of the coating and is not permanently released.

In order to take into account the influence of moisture and the ageing state of the tissues, ageing tests were carried out which lasted up to twelve weeks. It turned out that antimony oxide is exposed on the surface by ageing in humid air at simultaneously increased temperatures.

To predict the release behaviour over longer periods of time at room temperature from laboratory data, a ‘Arrhenius’ method was used (quantitative temperature dependence in physical and above all chemical processes in which activation energy has to be overcome at the molecular level). Here it can be concluded that the influence of humidity is critical with regard to antimony oxide exposure under typical environmental conditions - ten per cent of the total antimony oxide contained escapes at 20°C after a few years.

Health hazard – Yes Or No?

For the assessment of a possible health hazard from antimony oxide, specks of dust that enter the lungs when inhaled are particularly relevant. However, the investigations presented here only examine the basic possibility of superficial exposure. Explicit investigations on the release of dust were not carried out. As long as the material is embedded in the polymer, no relevant exposure of a user can be assumed.

However, it is not sufficient to evaluate the tissue only in its new condition. A possible exposure or release of antimony oxide must also be excluded during use. In the sense of a risk-benefit assessment, the use of antimony oxide as a flame retardant synergist can be quite sensible in the case of a justified need for efficient flame retardancy in fabrics with thin coatings.

At present, further efforts are being made to evaluate and classify the health-endangering potential. A possible regulation by "REACH" (an EU regulation) is not to be expected in an estimated period of about ten years, according to the „Bundesinstitut für Risikobewertung“ (Federal Institute for Risk Assessment).

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