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Pumps and Systems Report
Pumps and Systems Report Bredel industrial hose pumps convey corrosive media in flue gas purification Bredel hose pumps, a brand of Watson-Marlow Fluid Technology Solutions, offer a powerful and reliable solution for many pumping tasks in energy-from-waste plants. In the AVA Velsen waste treatment plant, the pumps were able to prove their suitability in the processing of corrosive and abrasive media in several process stages of flue gas purification. In the process, they offer longer service life and lower costs than the centrifugal and rotary lobe pumps previously used. The Zweckverband Entsorgungsverband Saar (EVS) is an association of all 52 municipalities in the German state of Saarland. EVS is responsible for regional wastewater treatment and environmentally sound waste disposal throughout the state. The non-recyclable waste, especially a large part of the residual waste and commercial waste, is thermally recycled in the waste incineration plant AVA Velsen. In total, about 255,000 tonnes of residual waste are thermally recycled annually in AVA Velsen, generating about 150,000 MWh of electricity. This is achieved by optimised waste allocation and low-fault operation, based on the consistent use of modern and reliable technologies. Hose pumps in the flue gas cleaning system The flue gases produced during waste incineration are fed into a multi-stage flue gas cleaning system to remove pollutants. For flue gas scrubbing, the gas is first cooled in the so-called quench, by intensive spraying with water, which flushes out the first pollutants. The contaminated wash water (“quench water”) is later subjected to further treatment steps to precipitate and filter out more pollutants. Initially, several centrifugal pumps were used throughout the plant to transport the wash water. Since the wash water is very acidic (pH 0) and highly corrosive, these pumps repeatedly broke down: The mechanical seals of the centrifugal pumps proved to be especially susceptible to damage and had to be replaced frequently, reports the team leader of AVA Velsen GmbH responsible for the wastewater treatment and evaporation plant. In many cases, the damage even proved so serious that the entire pump head of the centrifugal pumps had to be replaced - with considerable costs for spare parts and downtime. Pumping without seals and valves AVA Velsen GmbH found a solution to these problems in the hose pumps from the supplier. These pumps require neither seals nor other additional equipment such as ball check valves, diaphragms, immersed rotors, stators or pistons, which can leak, clog or corrode and then have to be replaced at great expense. No moving pump components come into contact with the medium. The only spare part in the hose pumps is the precision-manufactured hose element. Depending on the application and purpose, it is available in a variety of different materials, including EPDM, which offers excellent resistance to aggressive chemicals and concentrated acids. A total of four centrifugal pumps in the wastewater treatment plant were replaced with industrial hose pumps. With great success: The service life of the EPDM hose elements enabled total costs to be reduced by more than 50 percent compared to the previously used centrifugal pumps. High reliability in the processing of limestone slurry Fig. 1: At AVA Velsen, about 255,000 tonnes of residual waste are thermally recycled per year and approx. 150,000 MWh of electricity are produced (all photos: Watson-Marlow Fluid Technology Solutions) The industrial peristaltic pumps have already been able to prove their suitability for difficult and demanding pumping applications in another application at AVA Velsen: During a subsequent process step, limestone slurry (“milk of lime”) is added to the wash 32 PROCESS TECHNOLOGY & COMPONENTS 2023
Fig. 2: Industrial hose pump for pumping very acidic (pH value 0) and corrosive washing water. Since only the hose elements made of EPDM touch the aggressive medium, it offers a long service life. water in a treatment plant, thus enabling the sulphur dioxide to be filtered off in the form of gypsum. A rotary lobe pump was initially used to transport the limestone slurry. Due to the abrasive character and relatively high solids content of the limestone slurry, this pump proved to be very susceptible to breakdowns and caused high repair and downtime costs. The solution here was also a robust industrial Fig. 3: Pump to process lime slurry with a high solids content without any problems. Fig. 4: The direct-coupled design combines the reliability of the long-coupled design with the advantages of the compact close-coupled design. hose pump from the manufacturer. The pump now delivers the milk of lime with a high degree of reliability. The hose elements used achieve a service life of about nine months, reports the team leader. For safety reasons, however, the hose element is replaced every six months as part of planned maintenance. The costs for this are very low compared to the repair costs of the rotary lobe pump and moreover, the replacement of peristaltic hose elements can be carried out quickly and easily onsite. For these reasons, the hose pumps in various sizes are now also used in the AVA Velsen for pumping a saturated NaCl solution as well as filtrates. As the pumps are exposed to a corrosive atmosphere, the components have been made of stainless steel wherever possible. The pumps are also painted according to the C4 painting standard or are protected with a double layer of paint. More over, the pump manufacturer offers pumps with a paint-free, galvanically coated pump housing for aggressive atmospheres. Ideal solution for many applications in energy-from-waste plants At various application at AVA Velsen, the pumps are demonstrating the numerous advantages of peristaltic hose pumps for processing aggressive or abrasive pumped media: They offer a suction head of up to 9.5 metres, are self-priming and offer good dry-running capabilities. Without internal seals or valves, no moving parts come into contact with the medium, and they impress with their high reliability and low maintenance requirements. Maximum reliability is also ensured by the manufacturers patented direct-coupling technology: it combines the reliability of the long-coupled design with the advantages of the compact close-coupled design: An innovative buffer zone protects the gearbox, bearings and pump head in case of leakage. Heavy-duty pump rotor bearings support the radial load, so the drive shaft transmits only the torque and speed needed for the specific application. Depending on the pump model and size, the hose pumps offer a high flow rate of up to 108,000 litres at a pressure of up to 16 bar and convey abrasive slurries, pastes and viscous media with up to 80 percent solids content with 100 percent volumetric accuracy. Therefore, the supplier’s peristaltic pumps are the first choice for many applications in the environmental and energy industries. In these industries, they are used wherever corrosive, viscous, abrasive or other difficult-to-handle media PROCESS TECHNOLOGY & COMPONENTS 2023 Problem solver for process engineering and sewage technology www.eggerpumps.com Turo ® Vortex series T and TA Suitable for high solids concentrations and shear sensitive products in the chemical industry and for clogfree pumping of raw sewage with fibres and sludge. Iris ® Diaphragm Control Valve Highly precise and energy saving control of flow rate through concentric Iris ® diaphragms. For aeration airflow control in WWTP’s and for gases or liquids in industry. SWISS ENGINEERED PUMPS SINCE 1947 Switzerland Emile Egger & Cie SA Route de Neuchâtel 36 2088 Cressier NE Phone +41 (0)32 758 71 11 Germany Emile Egger & Co. GmbH Wattstrasse 28 68199 Mannheim Phone +49 (0)621 84 213-0
