Pumps and Systems Dry-running magnetic coupling pumps Avoiding unplanned downtimes and saving costs Intrinsically safe pump operation proves itself in practice Annette van Dorp From unpopular to indefensible - the views on unplanned downtimes differ depending on the difficulties and causes involved. One thing is certain: unplanned pump downtimes are always associated with additional effort and costs. In manufacturing industries they often lead to production stoppages and, in the worst case, to delivery bottlenecks. In order to minimize the risk of centrifugal pumps failing, the practitioner puts his faith in a redundant design, the sufficient stockpiling of spare parts and continuous training of the personnel. Increasingly, digital diagnostic and early warning systems for fault detection are being offered and used. These are supposed to intervene in a monitoring, protective and regulative way. Then again, these systems are expensive to purchase and can lead to misinterpretations or false alarms. processes montan wax – an important basic material for many branches of industry. Special processes are used here to refine hard waxes that are required in cosmetics, paints or plastics production. They are also used as agents in ceramic and metal die casting and in the construction industry. In a multi-stage extraction process, water is removed from the lignite by drying. The granules are then sieved and crushed. In an extraction process, a hot solvent (toluene) flows through the coal bed and dissolves out the wax. The raw montan wax contained in the solution is freed from solvents in evaporation columns. Here is where the pump is used. The first challenge: Up to 30 % of the finest carbon particles – often in the micrometer range – may be contained in the pumping medium. Due to the regular failure of the pumps, the entire process reliability was in danger. The problem was that the standard centrifugal pump with double mechanical seal – redundantly designed – cannot cope with the process. The next challenges: Depending on the temperature in the plant, crystallization processes occur in the wax mass. Furthermore, the pump operates close to the boiling range of the pumping medium. The conse- The pump manufacturer Bungartz has been proving for years that it is also possible without additional effort. The equally unusual and successful concept of the intrinsically safe pumps, which have, among other things, a dryrunning drive and a bearing unit of the same type, has a decisive effect on operational reliability and a long service life. In addition, these special centrifugal pumps score points with many other special features. A difficult process in search of solutions The situation: Unplanned downtimes in regular intervals followed by cost-intensive seal changes and considerable costs caused a good deal of annoyance at a manufacturing company. This was the inducement to look into the question of changing the pump. The company Fig. 1:The dry-running magnetic coupling pump is extremely low-maintenance. The sealing and bearing technology operate independently of the pumping medium and are therefore completely wear-free. 32 PROCESS TECHNOLOGY & COMPONENTS 2021
Pumps and Systems Dry-running magnetic coupling pumps quence was that the entire plant had to be shut down unscheduled every 2–3 months. This state of affairs and the associated mechanical seal replacement became too timeconsuming and stressful. Stopping the process ultimately became too costly for the company. stands out thanks to its low operating costs such as the long service life of the bearings, low installation costs due to the standard dimensions and generous maintenance intervals (3 years). The low energy consumption also contributes to its efficiency and sustainability. Successful pump replacement helps to save An optimal solution for the difficulties identified was worked out by the pump manufacturer’s engineers by means of a precise analysis of the conditions. They decided in favor of a conversion. With the dry-running, horizontal magnetic coupling pump, a safe, cost-saving and efficient solution was found. Thanks to the standard dimensions of this pump, the conversion went smoothly. Furthermore, there was no need for a second pump any longer. Before the pump replacement, there was another pump in another stage of the process. On the advice of the specialists, the dry-running magnetic coupling pump now serves both processes. Savings are achieved not only from the elimination of the second pump and the associated follow-up costs (maintenance, etc.). The power consumption has also been significantly reduced: almost 65 % can now be saved annually. The two predecessor pumps required approx. seven amperes. This economical pump requires only two amperes. Fig. 2: Customer-specific solutions, innovative and continuous further development guarantee the successful pump operation. Special features of the design A single-stage horizontal chemical pump with a magnetic coupling was replaced and newly installed. Due to the intelligent design, in which the bearing unit runs without product contact, the hermetically sealed pump is capable of dryrunning at all times, which enables operation almost independently of the liquid. Between the rear of the impeller and the shaft bearing is a product-free labyrinth area through which sealing gas flows. This provides a heat barrier with a high temperature gradient, ensuring a low bearing temperature. Solids barriers provide effective liquid-solid separation. The shaft is equipped with grease-lubricated roller bearings. The ceramic containment can, which sits between the inner and outer magnet rotors, runs in a gas atmosphere without product contact and has only a low pressure load. It therefore ensures eddy current-free magnetic field transmission, which brings considerable energy savings. Even with a minimal load or a prolonged interruption to the flow of the medium, the triple seal arrangement ensures a very high safety standard. No damage occurs to the pump. The greaselubricated roller bearings with a minimum service life of 32,000 hours require neither monitoring nor maintenance. The ATEX-compliant design is safe against operating errors (e.g. insufficient venting) and blockages. Here, too, further monitoring and additional equipment can be dispensed with. The decisive criteria for use in all ATEX classes is the intrinsic safety of the dry-running magnetic coupling pump, which sets standards with its optimum operational reliability and its insensitivity to operating errors. In economic terms, it Features and Advantages of the Horizontal Replacement Pump – sturdy and durable design – dry-running and depressurized magnetic coupling – sealing and bearing technology operates independently of the pumping medium and is thus entirely wear-free – grease-lubricated roller bearings with a minimum service life of 32,000 hours – without maintenance – low installation and maintenance costs, low energy consumption, fast availability of all standard dimension sizes (www. bungartz.de/) The term intrinsic safety describes a factor that ensures that no dangerous situations occur even in the event of operating errors. The special pumps manufactured by Bungartz have this intrinsic safety, which makes external monitoring systems superfluous. The Author: Annette van Dorp freelance journalist, on behalf of Paul Bungartz GmbH & Co. KG, Düsseldorf, Germany Innovation consequently developed EIPQ 4-Q motor pump unit for closed or opened loop High dynamic Very high volumetric efficiency at low speed conditions Compact design NEW EIPS1 V th from 1,6 till 5 cm³/rev Compact design Very high efficiency Continues operating pressure till 300 bar Long lifetime Please visit us: eckerle.com ECKKL-21001_Anzeige_EIPQ_EIPS_185x60mm_EN.indd 1 12.01.21 15:48 PROCESS TECHNOLOGY & COMPONENTS 2021 33
