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PROCESS EQUIPMENT UPDATE


The slim design of the progressing cavity pump allowed the installation of four pumps together with frequency inverters on a carrier module


Rising to the challenge


From fine paper coating to high-viscosity paint, materials for surface coating represent extreme challenges to pump technology, explains Roger Willis


T


he printing and ink industry represents one of the most versatile application sectors for delivery systems. The areas of application include the reliable supply of abrasive paper fi llers and corrosive gluing


agents just as much as the exact metering of high- viscosity printing inks and varnishes. Standard pumps cannot cover such a wide range


of demands, especially since the usually very sensitive media require careful transport. Instead, this industry often uses progressing cavity pumps and rotary lobe pumps from Netzsch, which are marked by their wide adaptability and pressure-stable delivery characteristics. One of the major problems for conventional pumps


in delivering inks is the lack of fl uidity of the medium. Viscosities of 10,000 mPas and more are quite common. Continuous supply can therefore be achieved only with diffi culty; in addition, the pumps become clogged quickly. For example, a renowned publishing house struggled with repeated breakdowns at the diaphragm pumps used to refi ll off set ink at roughly 10,000 mPas from the transport truck to the storage tanks, which delayed the unloading process greatly. What’s more, the pumps often required maintenance work and had to be removed and dismantled quite laboriously. To increase performance and economy at this point, the company fi nally resorted to using Nemo progressing cavity pumps.


SPECIAL ADAPTATIONS Their delivery principle is based on a rotor that turns in an oscillating motion within a fi xed stator. Due to the design of rotor and stator, hardly any pulsation or shearing forces are acting produced on the fl uid. Instead, the medium is transported gently and continuously. Consistency and especially the viscosity are not a factor


14 www.engineerlive.com


for the fl ow with this displacement technology; the transported quantity is determined by the speed alone and – in combination with a frequency inverter – can be regulated conveniently and with precision. A single-stage L-geometry was used for rotor and


stator for this concrete application, which allows for a higher delivery rate at low diff erential pressure. The deliberately chosen undersize of the rotor prevents excessive clamping thereby improving mechanical effi ciency. Furthermore, the slim design of the progressing cavity pump allowed the installation of four such pumps – for the four printing inks – together with frequency inverters on a carrier module. This is integrated in the base plate of the transport truck and can be easily removed with a forklift truck. It allows easy access to the devices, in case maintenance work should become necessary at some point. Nonetheless, the pumps generally work much more reliably than the previously employed diaphragm pumps. To top it off , the unloading time for the ink was reduced by nearly half.


VERSATILE APPLICATIONS Positive displacement pumps from Netzsch are used in various areas of the ink and paper industry, for example to transport pigment sludge or additives, for process fl uids and binding agents. However, each scenario requires confi guring the pump according to its use. The broad experience of the company’s experts in the ink and paper market helps to fi nd the appropriate combination. ■


For more information ✔ at www.engineerlive.com/process


Roger Willis is with Netzsch. https://pumps.netzsch.com/en/


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