Efficiency and Optimisation for Compressed Air Equipment: Plenty of Room for Improvement

The life-cycle costs for compressed air equipment are just under 30 per cent of the capital expenditure - the remaining 70 per cent must be spent on the energy required for operation. Companies are therefore well advised to take advantage of all optimisation opportunities. Various projects in the early 2000s made it clear that there is no single recipe for increasing the efficiency of such systems. The simple reason: no two companies are alike.

The company Xervon in Cologne has now taken another approach, writes Hans-Jürgen Bittermann, an author at the trade journal 'PROCESS'. The compressor house looked after by Xervon in the Cologne-Merkenich Chemical Park for supplying compressed air to three chemical companies was modernised together with an energy supply company. The core of the conversion work was the investment in new compressors (two turbo compressors and three screw compressors). The redundantly designed compressors were connected to each other via a ring line.

The extensive sensor network was designed as a real-time monitoring system for all relevant measured variables in order to derive an optimal control system. Among other things, the pressure, the amount of air taken off, the air humidity, the ambient temperature and the power consumption are recorded digitally throughout. The control is based on manually programmed templates that determine which compressors should run under which conditions.

Procedures and Challenges for Optimisation

The goal is to optimise the operation of the system overall based on empirical values from the past. For this purpose, the recorded operating data is to be analysed with modern algorithms from the field of machine learning in order to understand correlations in a profound way and to derive perfect control from them.

Specifically, these findings in the field of data science/machine learning will be combined with the plant knowledge of Xervon's experts. The result is an overall system consisting of compressors from different manufacturers that are also highly dependent on site-related influencing factors. In order to evaluate the potential, two independent strategies were investigated: In the first, the current operation was evaluated using an ideal process, thus determining its efficiency.

In the second, a substitute design was fitted to the data based on the compression models developed by the company.

A special optimisation algorithm then searched for the control parameters with the lowest power consumption. With these strategies, a reduction in power consumption of a good four per cent could be demonstrated.

Artificial Intelligence Strengthens the Digitalisation Trend

In this optimisation challenge, a team of researchers from TU Dortmund University uses current algorithms that have already been tested for the optimisation of related disciplines.

This approach has already proven itself in the field of maintenance: In a past project, the service provider Xervon used artificial intelligence to develop an assistance system that facilitates the operation of the serviced cooling towers in Cologne-Merkenich. The tool developed as part of the project uses this data and a regression model to generate a forward projection for the energetically optimal operation of the cooling towers.

It is quite clear that digital, data-driven services will significantly expand their market share.

Photo:  weerapong


Green Hydrogen: The Challenge of Safety Engineering

In the course of the energy transition, hydrogen will become increasingly important – especially the 'green' hydrogen produced by electrolysis with renewable electricity. At present, the global share of electrolysis hydrogen is still very low at less than five per cent, which is due in particular to the high production costs. However, these will drop significantly in the future.
The entry into a 'hydrogen economy' is in full swing. Although the chemical industry is well-practised in handling hydrogen, new challenges arise, especially in the field of safety technology. From a safety point of view, the exceptionally low minimum ignition energy is an important factor. Also, because of the extremely high flame speed, which is about eight times higher than that of a methane flame, a hydrogen-air mixture is exceptionally challenging.
In addition to the danger of explosion, there is the fact that hydrogen molecules are very small and have a high diffusibility, even through solid metallic materials. Therefore, there are special challenges to the tightness of hydrogen equipment, which, however, can be mastered technically.

Safety Standards for Hydrogen

Internationally, there are several standards covering the safety-relevant aspects of the most important elements in the hydrogen value chain, including electrolysis.
Measures of primary explosion protection are intended in particular to prevent the release of hydrogen through sufficiently sealed plant components. This is ensured by monitoring the immediate environment with gas-measuring devices. Tightness is a determining aspect of most safety concepts for hydrogen plants.
In Germany, the two categories "technically tight" and "permanently technically tight" have been well-proven for many years. At the European level, this necessity has been taken into account in the latest edition EN 1127-1. However, the EN differs significantly from the German standards with regard to the concepts and some technical details.

Transport and Storage

The requirements for safety technology are also high for the storage, transport and re-conversion of hydrogen. As in the case of production, however, there are still no really adequate norms and standards internationally for all processes. The safety requirements for the operation of a comprehensive hydrogen infrastructure are not higher than those for fossil fuels, but neither are they lower – at least in terms of explosion hazards. Properties that are favourable in terms of safety, such as the high volatility due to the low density, are countered by less favourable properties such as the extremely low minimum ignition energy and the high diffusion coefficient.
In the future, hydrogen will not only be handled in plants well isolated from the public and operated by trained personnel, but many new applications will be decentralised. For instance, electrolysis plants will be built near wind farms, and extensive hydrogen supply and refuelling networks be established.
It is therefore very commendable that ISO and IEC address many important aspects of safety engineering along the hydrogen chains in international standards, writes Prof Dr Thorsten Arnold in the trade journal "Chemie Technik".

Photo: Negro Elkha

The Chemical Industry is undergoing a digital upheaval

"Speed becomes a competitive advantage" is the title of an interview in the trade magazine Chemie Technik in April 2022 with Tobias Gehlhaar, Managing Director of the Chemicals, Basic Materials and Utilities Division at Accenture on a study they prepared on the future of the chemical industry.

Chemistry is undoubtedly one of the great leading industries in Germany. It's really about the heavy industry and, accordingly, the challenges are similar. "The exciting thing for me here is especially how companies from this sector are now increasingly approaching topics such as digitalisation and AI and adopting new technologies," says Gehlhaar, adding, "I believe that it is necessary for companies in the current phase of upheaval to place one or two 'bets' on the future."

He sees one problem with the issue of fuel procurement and energy efficiency and believes that we will see much more cooperation between the two areas in the future. One stumbling block here, he says, is that German industrial companies in particular are very reluctant to enter into partnerships at eye level. The idea that you alone have to determine value creation is in part very deeply anchored in corporate cultures.

Where will it go in the Future?

There are certainly examples in recent economic history that show us where the journey could go, argues Thomas Gehlhaar: "In the financial sector, for example, we have seen that some innovations in this area have not taken place with the big players, but with small start-ups, the so-called fintechs".

Such a development is also possible in the chemical industry, especially against the backdrop of the emerging distortions in the energy sector. The idea that assets protect a company in the long term is wrong. As soon as innovations become established, there are two possibilities: Either the innovators do not manage to scale themselves, in which case the innovations spill over to established companies and they can use them or market them. Or else, new players emerge - as in telecommunications and technology, for example - which then "steal" a substantial part of the margins from the big players.

How the Chemical Industry Should Reposition Itself

New regulations and rules, for example in the field of energy transition, will make speed and readiness for change a competitive advantage in the coming years. If it is then soon no longer primarily about production capacities and quality - all things: in which German industry is traditionally strong - then this will become a problem, says expert Gehlhaar.

In the end, it's a question of how quickly a company is able to move from an idea to its implementation. They should take a self-critical look at the question 'where do we stand'? This is then about different release levels, hierarchies in the company and so on. An honest stocktaking is a very helpful measure here, Gehlhaar emphasises.

If companies only think in terms of their own product lines and develop them incrementally, the next disruption that completely turns the market upside down will not emerge. And that may mean making investments in an area for which there is currently no market at all.

Original source and quotations: Trade journal Chemie Technik – the original interview was conducted by editor Jona Göbelbecker.

Photo: Yellow Boat


Production Of Man-Made Fibres: Specially Adapted Water Treatment Plants For Complete Demineralisation

From spinning to cable production and fibre cutting: all these work stages require fully demineralised water (demineralised water) – almost pure water that is largely free of electrolytes and has low conductivity. About 70 per cent of the water is used for the production of polyester products. In order to induce desired chemical reactions or not to disturb them, the water must be as salt-free as possible. Individually adapted water treatment systems can ensure significantly lower maintenance requirements and higher economic efficiency.

With fully demineralised water, fibre manufacturers avoid, among other things, deposits in the steam boiler, which could often lead to corrosion damage and, in the worst case, even to the bursting of a boiler. All other containers, pipes and fittings with which the water comes into contact on its way through the production stages are also protected by demineralised water, provided they are made of suitable materials.

Reliability And Reduced Logistics

Customised water treatment systems should deliver the desired pure water of the highest quality, without the use of hazardous substances – and they should also simplify maintenance and be available around the clock. In fact, a breakdown might cost several hundred thousand euros a day. Therefore, the reliability of such a plant is an extremely important criterion.

In the past, the preparatory work alone for the beginning of the desalination process was much more time-consuming. For example, about 300 kg of regeneration salt had to be manually filled into salt containers from 25 kg bags every day. This high logistical effort is avoided by the new solution, in which large brine bunkers are created (in the size required by the company), in which brine is continuously formed and used to feed the brine measuring vessels of the softening plants. In this constellation, the necessary salt is delivered in silo trucks only every 1.5 months.

Second Purity Stage with Reverse Osmosis

In reverse osmosis plants, semi-permeable membranes are used that are only permeable to water but not to salt. In this stage, full desalination and the desired 'pure water' are finally achieved. All parts of the system with which it comes into contact have a longer life and need to be maintained or cleaned only very rarely. And this also applies to the central element of steam generation, the steam boiler. Any residual amounts of salts that may be still present have to be removed several times a day by drain depressurisers.

The boiler water, which is over 200° C, is cooled down to 40° C so that it can be discharged into the wastewater system. This is done using existing soft water that comes directly from the softening plant and is stored in the drain depressuriser.

Photo: chinnawat

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