Plant & Works Engineering February/March 2023

G iven the global rise in energy costs, there has never been a better time to review and assess the efficiency of your pumping systems – whatever their size, complexity or indeed area of operation. Pump systems account for 20% of the worlds electrical energy demand and between 25% - 50% of the electrical energy usage in certain applications. Pumps are the single largest user of electricity within industry across the European Union, consuming over 300 TWhpa of electricity, which in turn accounts for over 65 Mton of CO? emissions. It is also well documented that rotodynamic pumps which account for 80% of the installed base are between 20-30% oversized. There is therefore a major potential to save energy if rotodynamic pumps are properly sized and operated. Where to start - Assess the potential for savings Understand your pumping system: To identify if a pumping system is sized correctly make the following checks; • Are you wasting liquid flow? • Are you creating additional pressure? • What is the monitoring & controls philosophy? • Are there any oversized pumps installed for your required duty? • Are there any old pumps employed in the system? • Is there excessive noise in the system? • Are there any throttling valves installed in the system? • Have you the correct size of pipework installed? • Inadequate maintenance lowers pump system efficiency, so what maintenance procedures are in place? • Are you adopting a proactive equipment replacement programme to current EU legislation Available Technology - Choosing the right equipment Understanding Drive Technology: Use latest EU regulation to achieve best possible drive efficiency; • Variable speed drive (vsd) Process, Controls & Plant Focus on: Pumps & Valves 24 | Plant & Works Engineering www.pwemag.co.uk February/March 2023 Optimising pump systems Gary Wilde, Technical Services Officer at the British Pump Manufacturers Association (BPMA) offers some basic information and guidance on purchasing, maintaining, and designing pump systems for optimum energy efficiency, CO 2 reduction and capital expenditure payback time. • Integrated control and monitoring • Permanent magnet technology Choose your supplier - Making the right choice This article does not suggest or promote any single supplier or technology. It does however recommend that you choose a supplier that is a member of the BPMA, and as such offers the assurance that it operates within the organisations agreed standards and Code of Practice. The vast majority of existing pump systems operating today were not originally designed with energy conservation as a major consideration. If pump systems are initially designed on an energy efficient basis and pumps are correctly applied and sized the energy savings will often be in excess of 50%. To design an energy efficient pump system all the following criteria should be considered: • Basic plant layout • Pipe size, configuration, and restrictions to limited pipe work losses • Information on the liquid, (viscosity, density, aggressiveness, temperature) • System characteristics and pump selection • Pump/System control • Avoid oversizing of the pump units • Selecting the most energy efficient pumps at the best efficient point • Fitting VSD’s to match the system design & demand Reduced energy costs are a direct result of selecting the correct pump and matching it to the system. When selecting a pump, it is important to determine the required flow and pressure to be generated by the pump. The flow may be determined by a process requirement, by the heating or cooling required in the system or by the peak water demand for utilities. The pressure required may be to elevate the liquid within the system or to overcome the pressure losses in the system created as liquid passes through it. It is important to know as much about the pump system as possible and to create a pressure/flow profile for the system. The energy required to drive the pump is directly related to the flow and pressure required. To generate high pressures generally leads to designs which may be inefficient and therefore it is important that neither the flow nor the pressure is over specified. Variable speed drives can save energy It is estimated that significant energy savings have already been made by using Variable Speed Drive and High Efficiency motors. Generally, Variable Speed Drives are used to continually adjust the speed of the pump to the demand.