Design and fabrication of novel, geometrically optimised conical inline filters/strainers for use in the process industries.

Vijayakumar, Bhavani and Rennie, Allan (2020) Design and fabrication of novel, geometrically optimised conical inline filters/strainers for use in the process industries. PhD thesis, Lancaster University.

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Abstract

The consumption of energy, raw material and water have been increasing in the past half-century due to economic growth, rising of the middle classes and overpopulation. This led to scarcity of the limited natural resources. Thus, conserving energy and natural resources by changing manufacturing methods, recycling and optimising processes/ equipment design to reduce energy and material consumption are high in priority. Pumping equipment consumes 13% of energy in process industries in the UK. In order to protect them from getting damaged due to debris, these pumps are fitted with conical in-line filters/ strainers consisting circular perforated holes. These filters are not designed to aide optimum flow and are made using subtractive manufacturing technologies. Research has shown that, positioning the holes right angle to the fluid flow direction and changing the manufacturing method to Additive manufacturing (AM) yielded reduction in pump energy and material consumption. Building on that, various design optimisation strategies such as the shape of the perforation, height and shape of the filter were considered. Reviewing the literature, it was identified that fluid flow in a pipe creates a parabolic velocity profile (VP), where the velocity increases in concentric circles from zero on the pipe surface to maximum in the middle. Therefore, the perforation on the AM conical filter ‘3”Plain’ consists of concentric rings held by eight strands along the conical form instead of circular perforation. Based on the perfect fluid dynamic body shape of some sea species, the filter shape was modified from cone to resemble; Squid, head and neck of Gannets, chinstrap Penguins and finally the Gherkin to resemble the VP. Further modification was implemented in the form of 45o angle between the pipe and filter to utilise the entire filter surface. Three filter supports the conventional filter support (CFS) (height =160mm), 3”Plain (height =160mm) and Squid1 (height =120mm) of same base diameter (76mm) were used for the experiments. The experiments conducted were; without mesh, with 28 mesh, and with 20 mesh. The results revealed that the performance of the 3”Plain filter was better than the CFS. The energy that could be saved with a 3”Plain with 20 mesh is up to 28.849 kWh, which is equivalent to 22,214 £/year. The Squid1 despite being shorter by 40mm was equally as good as the 3”Plain. The experiment with just the 20-mesh revealed that the use of any filter support significantly increases the pressure drop. Therefore, further design optimisation should consists free mesh in an optimised shape and stable structure. Inspired by the length diameter ratio of Dolphins, an attempt to identify the optimum height of the filter support using Flowsimulation software revealed, the optimum height for the filter lies within the range of 4 to 5 times the filter diameter. The environmental baseline comparison reveals that changing the manufacturing process to AM, will significantly reduce the use of Tri-Ethanolamine (Cooling and lubricating fluid), a carcinogen. Based on the information provided by the industrial partner, 33% of the sheet metal is sent for recycling. When calculated using a CAD software, material sent for recycling for CFS was found to be 63.7%, which is presumably 53% higher than the AM filter support. Thus, with appropriated design optimisation and manufacturing process of a filter support, significant energy and material could be conserved.