Water and Effluent Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/615834
january 2016 WET NEWS 17 F luid handling equipment may suffer from multiple problems including physi- cal and mechanical damage as well as general or localised erosion and corrosion. These problems are linked to decreased efficiency and poor perfor- mance, leading to increasing operational costs. Minimising performance Minimising performance deterioration is an important factor where pumps are concerned, with frictional forces to blame. The challenge: Eliminating friction THE CONCEPT • Belzona 1341 (Supermetaglide) is a high performance coating for improving the efficiency of pumps, pipes, valves • The pump's hydraulic performance can be increased because of the smoother surface and reduction in flow resistance and friction • The coatings possess a low electronic affinity towards water molecules NEED TO KNOW 1 Hydraulic losses account for most of the efficiency decrease 2 The loss of efficiency is caused by frictional forces created between the fluid and the walls 3 The smoother the pump walls, the more fluid turbulence will be reduced THE VERDICT The results after coating the pump and changes to the programming of the water elevation plan were: • reduced energy consumption during non-peak hours 44.9% to 39.3% (-12.5%) • reduced energy consumption by 14.9% (kW / m3), 147,247 KW/h recorded in eight months • 20.3% cost reduction • rOI: Four months of operation INSIGHT PuMPS & valveS The Belzona 1341-coated pump gave a maximum of 6% increase in peak efficiency and a 5.1kWh reduction in power consumption deterioration is therefore an important factor for pump manufacturers and end users. Indeed, hydraulic losses account for most of the efficiency decrease – 9% for a mixed flow pump to 20% for radial flow. Coating technology can help in decreasing these losses, increas- ing the pump's performance and reducing operational costs. In pumping equipment, it is possible to reduce power consumption and improve the hydraulic properties by chang- ing the pump surface finish. In fact, the loss of efficiency is caused by frictional forces created between the fluid and the walls, the acceleration and the slowing down of the fluid, and the change in the fluid flow P olymeric coatings are specifically designed to im- prove efficiency on fluid handling systems and protect metals against the effects of ero- sion-corrosion. Properties such as self-leveling application, hydrophobicity and hydraulic smoothness makes these coat- ings ideal candidates for lining the hydraulic passages of pumps. These coatings possess a low electronic affinity towards water molecules and result in a smooth glossy finish once applied onto a metallic surface. This allows the water or other aqueous solutions to easily slide on the surface of the coating. The Belzona 1341 (Super- metaglide) is a high perfor- mance coating designed to improve efficiency of pumps, pipes, valves and other fluid handling equipment while pro- tecting them from the effects of erosion-corrosion. It has been measured as 15 times smoother than polished stainless steel. As a result of the smoother surface and reduction in flow resistance and friction, the hydraulic performance of the pump can be increased. A test by the British National Engi- neering Laboratories compared the performance curves of a single stage, end suction cen- trifugal pump with a 250mm suction and discharge branches before and a—er being coated with Belzona 1341. The pump, in uncoated condition and run- ning at 1,300rpm, was origi- nally found to deliver 875m 3 /h at 26.5m head and with overall peak efficiency of 83.5% (overall efficiency defined as the ratio of water power output to mechani- cal power input at the sha—). Testing of the Belzona 1341-coated pump gave a maximum of 6% increase in the peak efficiency and a reduction in power consumption of 5.1kWh at duty point. Assuming a 5,000 hours operating cycle/ annum, the power savings over this period would amount to 25,500kWh. In 2013, a water elevation plant in Portugal was looking for a solution to improve its hydraulic efficiency. This plant was chosen because of its high energy consumption and costs, with an annual consumption of 1.7GWh/year and a volume of water propelled of 1.2Mm 3 /yr recorded in 2012. The client was looking for a reliable and long-term solution Polymeric coating solutions can improve water efficiencies and protect against erosion-corrosion. A solution: Smoothing the finish to restore the damaged pump while reducing internal friction in the impeller and volute to enhance hydraulic efficiency. An internal pump coating was chosen to maximize water flow and reduce energy consump- tion while reducing internal wear and minimize future maintenance actions. The pump was disassembled and all internal surfaces were grit-blasted to remove the previous coating, creating a substrate cleanliness of at least SA2,5 and a surface profile of at least 75μ. The surface was then cleaned and examined to ensure that it was free of dust and other particles. A—er grit blasting, the appli- cation areas were masked for the application of Belzona 1111 (Super Metal), an epoxy paste grade composite for metal repair. Simply applied using an applicator provided with the product, this material was used to reconstruct the areas dam- aged by corrosion, rebuilding the original surface profile. This solvent free composite provides excellent corrosion resistance and ensures the substrate is protected when it comes in con- tact with an abrasive material. Within the two-hour over coating window, the first coat of Belzona 1341 (Supermetalglide) was applied by brush, followed by a second coat to obtain a total dry film thickness of 500μ. This coating was specified because it provides protection against erosion and long-term corrosion of equipment, whilst improving the efficiency of the pump. direction. The smoother the pump walls, the more fluid turbulence will be reduced, thus reducing the energy required for the pump to move the fluid through the hydraulic passage. In order to get the best performance possible, pump manufacturers seek to create the smoothest surface possible to reduce the turbulence of the fluid. This can be obtained by the polishing of the selected metal, such as stainless steel; however, this method is extremely time consuming and expensive. A smooth surface finish can also be obtained by applying an erosion-corrosion resistant efficiency coating on the pump's volute and impeller.