Smart Reisner refrigeration system for new DRS pipe extrusion plant

Great success for companies often comes with great challenges: For DRS, several favourable events occurred in 2019, and in the end the pipe manufacturer more than doubled its production output. A breathtaking development, recalls managing director Andreas Seibel. Whereas DRS previously operated six extrusion lines with an output of 300 to 400 kilograms per hour, six new lines with 900 to 1,000 kilograms each were now to be added. Furthermore, the machine park was expanded to include a new injection moulding machine with a clamping force of 200 tonnes and a new re-granulation system.

The right partner to starting a major project with

Cooling system container and dry coolers are placed between the new silos on the DRS outdoor area, where they are well protected

While negotiations with their new customer orders were still underway, DRS began their search for reliable partners to implement the expansion measurements. They could clarify the spatial situation at short notice because they were offered a neighbouring plot of land including suitable commercial property. Immediately afterwards, the issue of cooling came up. With only the existing refrigeration systems, DRS would not have been able to supply the new production under any circumstances. "We have made a very conscious decision for the new step in our business development, and thus we carefully selected our suppliers," reports Seibel. He already knew Reisner cooling systems from previous professional stations, both from the user's point of view and through recommendations of his customers. Nevertheless, he asked for several comparative offers: "We had high demands on the cooling technology. With the dimensions and the foreseeably complicated schedule, consulting, conception and finally project management were also important issues. That's why we invested a lot of time and intense thoughts into selecting the best offer".

The Reisner concept has convinced Seibel in several respects, especially because the refrigeration specialists from Holzwickede analysed the production beyond their own field and included the overall situation: "Reisner was able to offer an unrivalled, short delivery time. They could not provide the new refrigeration system at the start-up phase of our new production lines, but they supplied a rental system which allowed up to set up and test the new plastic processing lines. The situation was turbulent, requirements changed at short notice, but the team adapted without any problems. We felt well advised right from the start, also by Mirko Jurke from Reisner's sales partner Jurke Engineering GmbH - and we felt excellently accompanied during the whole planning phase".

Adding to the performance while saving energy

Three cooling units with a capacity of 400 kW each plus the respective control cabinets are installed inside the container

The most important factor, however, was the unique energy saving concept developed by Reisner managing director Thomas Imenkämper and his staff. It is based on the fact that the new DRS production requires a lot of cooling capacity, but it does not always need to be supplied at full load. The tailor-made cooling system therefore consists of three separate cooling machines. Each machine has a maximum cooling capacity of 400 kW, so that a total of 1,200 kW is available. The individually programmed Reisner control system regulates which machine contributes which amount of cooling performance at any given time. This demand-oriented supply goes even further, as each individual unit can be regulated again and thus reduced a partial load of up to 25 percent. Consequently, energy consumption is always kept as low as possible in any given production situation. As an attractive side-effect, the self-sufficient operation of the individual cooling units also boosts operational safety.

Reisner has even enhanced the energy saving effect by adding further technologies that also reduce the consumption. An important feature is the Reisner Vario technology. It allows the cooling machines to adjust their condensation temperature to the low average outside temperatures that are common in Germany. The lower the condensation temperature, the more efficient the refrigeration system. Thanks to precise control, DRS also save energy operating their condensers. They are equipped with EC fans which adjust their output precisely to the respective operating point, reducing not only energy consumption but also noise emissions. Finally, two dry coolers, also equipped with EC fans, supplement the cooling system. Each of these dry coolers provides up to 600 kW cooling capacity. Together, they gradually relieve the refrigeration systems when outside temperatures decline, and during wintertime they can even completely supply the production, reducing the chillers' compressor energy by 100 percent.

Extreme effects

From all these measurements, Reisner have assembled a complete package that effectively keeps energy consumption as low as possible under given circumstances. The figures speak for themselves: without energy-saving technologies the DRS refrigeration system would consume 1,366,743 kWh per year. The Vario technology alone reduces energy consumption by 550,687 kWh, while the winter relief system saves a further 636,784 kWh per year. This reduces electricity consumption to just 178,272 kWh per year - drastic savings of around 87%! Costs are reduced accordingly. While with a conventional system DRS would have to spend 205,011 Euro per year on cooling energy, using the Reisner system they get away with no more than 26,891 Euro.

Our environment benefits from the fact that much less CO2 is emitted to provide the necessary electricity. Annually, based on the local power mix, the Reisner concept saves the atmosphere around 630 tons of carbon dioxide. In addition, the system is designed for the future as it is operated with the state-of-the-art refrigerant R513a. This substance is much less harmful to our climate than comparable refrigerants. Its so-called Global Warming Potential (GWP) is only 631, while the reference value of CO2 is 1 and the refrigerant R410A which is still frequently used today has a GWP of 2,088. This way, even in the long run DRS won't have to fear that their cooling system operation could be affected by stricter environmental protection regulations.

A practical solution for every problem

The cooling water is perfectly stored within large custom-made Reisner tanks. The piping was manufactured by Reisner - using FRANK Group materials

Today however, DRS had to overcome very practical challenges. The adjacent sites had to be converted, new production and storage areas had to be created within record time. Among other things, the company commissioned six huge new silos, each with a capacity of 75 tonnes. Foundations were laid, the infrastructure rebuilt, and numerous new machines delivered and tested. Suitable refrigeration technology was always on hand, but never in the way. "Reisner integrated our new cooling units directly into a container", reports Andreas Seibel, "we only had to provide a foundation. On the inside the container was already perfectly piped and wired, so everything went very quickly. We have gained more space with the new building, but we are still glad about every cubic meter that stays available for actual production purposes". The container with the cooling technology is safely and securely located next to the silo system and can be quickly and easily moved to another location should need arise - for example following a production restructuring.

With the connections from the container to the tank Reisner covered a special request asked by DRS and used materials manufactured by the FRANK Group DRS belongs to. These materials are state-of-the-art PE100-RC pipes, that unlike standard PVC pipes are completely sealed by leakproof welding. Details like this as well as the reliable and confident work of Reisner's project planning department made the difficult tasks much easier for Andreas Seibel. "We continued to produce during the reconstruction phase, in three shifts and with an enormous material turnover. Each day, we had 30 to 40 trucks collect our finished pipes. Nothing could go wrong with the extra tasks. But we knew throughout the process that we could rely on Reisner", he remembers, "our contact person was project manager Detlef Badziong. Thanks to his many years of experience he reacted confidently even to spontaneous changes of plans. Thus, despite all efforts, the joint work on the project was really fun for everyone".

These canisters containing biocide and corrosion protection are connected to the Reisner dosage system

Cooperation for the future

For the near future, the project partners plan to jointly monitor how the energy-saving measures prove themselves in practice. "As we have only been producing since November 2019, it is still too early to take stock," reports Seibel, "but we will remain in close contact with Reisner in this regard. Together with Jurke Engineering we will monitor consumption and besides have the regular preventive maintenance carried out by the Reisner team".After the project phase which started in July 2019 and ended in November, DRS could start their day-to-day production as they had planned. Commissioning of their new cooling system in November went smoothly, as Reisner had already laid the foundation stone during the conception phase. Robust components and a maintenance-friendly design of the container make service operations an easy task. An integral part of this future-oriented plan is the cooling water quality. In pipe extrusion, water is often highly loaded with solids which can ultimately impair the function of all plant components. Therefore, Reisner have installed their unique full flow return filter system inside their custom-made 20 m³ production tank. Without any risk of backwater flow nor great maintenance effort the filters keep the water clean and thus protect the entire production. Dosing systems for biocide and corrosion protection agents complement the water care concept and spare the DRS staff from having to handle the chemicals.

For the near future, the project partners plan to jointly monitor how the energy-saving measures prove themselves in practice. "As we have only been producing since November 2019, it is still too early to take stock," reports Seibel, "but we will remain in close contact with Reisner in this regard. Together with Jurke Engineering we will monitor consumption and besides have the regular preventive maintenance carried out by the Reisner team".

Factsheet: Cooling system, 2019 for the DRS Deutsche Rohrwerke Sachsen GmbH