Hydraulics & Pneumatics September 2022

COMPRESSED AIR or extreme duties – can result in lowered pressure on the entire system and reduce energy consumption. It’s an easy route to add another compressor, but taking a holistic approach, analysing and optimising the existing system and its elements, is the key to safeguarding your assets and achieving the desired energy efficiency improvements. Let’s Audit, Right-Size, and Implement Before making a decision on what to do, whether to replace a compressor, add another one, or adjust the existing system, an audit of the operations is necessary. A compressed air auditor can check the entire system and establish the input, the state of the compressor units and how they are running, and what exact pressures are required. This will paint a picture of the system with its surroundings, elements, pipework, and critical consumption. With this knowledge, we can move to the next step, which is making an educated decision on how to optimise it to meet the new requirements. Very often, the new, expanded production requirements can be met with the same power but adjustments to the airflow (of course, depending on the size of the expansion). It’s all about right- sizing the air needs. Let’s show this based on a concrete example. A plant with current compressed air demand is expanding its operations and requires an increase of up to 35% in compressed air. Our job is to see how this additional compressed air demand can be achieved and whether adding a new compressor is necessary. The audit shows the system’s current state, including piping, running pressures throughout the day, and the cyclical changes in demands. The next step is to see how the existing system can be optimised to generate the additional demand within the same power. This can be done by analysing and rightsizing the system and taking a closer look at: Impact of leakage – Leakage happens throughout the system over time. It can be caused by aging hoses, improper joints, installations, wrong parts, or corrosion. We estimate that even 20 to 30% of compressed airflow can be lost due to leakage. Leakage via a 3 mm (~1/8”) hole can consume 4 kW/h of electricity, incurring an annual loss of 19,200 kW (at 7 bar g. (100 psi g.) 16 hrs/day for 300 days in a year). This is creating enormous room for improvement. Leaks occurring in pipe joints and connections can be prevented by simple, appropriate tightening and proper seals and sealing media. Suitable quality fittings, tubing, and connections last longer. An audit can establish risk areas while having a leak detection and maintenance programme at regular intervals will reduce future leakages. Inappropriate use of compressed air can mean many simple and ordinary things like blowing off washed parts or even operators who work in a dusty environment and use the compressed air supply to blow off the dust from their clothing. These things happen. Checking and eliminating inappropriate use of compressed air throughout the plant can contribute significant gains. Artificial demand is the excess volume of air required by unregulated end-uses as a result of supplying higher pressure than necessary for applications. This equals an unnecessary consumption of energy. A simple strategy of performing the proper selection, installation, and use of pressure controllers on top of preventing leaks and inappropriate use can be of great help here. Optimizing the pressure band - Setting the correct pressures can be done by establishing and understanding the requirements, determining pressure losses in the piping system between the compressor and the production equipment, setting the proper load and unload pressure as low as possible to meet application demands. The savings of reducing 1 bar (14.7 psi) of compressor set pressure is even 7% of the total compressor power consumption. Annually, with 16hrs/day of operation for 300 days a year, a 7% savings in case of 110KW compressor power consumption equals 36,960 kWh. Minimising pressure loss - While no system can be without a pressure loss occurring in the piping system and downstream equipment – the pressure difference between the point of discharge from the compressor and point of consumption – can be minimised and kept as low as possible. It starts with the piping design – placing the production and application points close to each other and optimising the size and shape of the piping. Downstream equipment should be selected at the lowest pressure drop, and maintained following the air compressor supplier recommendations, and cleaned periodically. All this keeping in mind that loss of 1 bar of pressure will incur 7% of the total energy consumption of a compressor. A properly executed audit with the right partner will show a complete consumption pattern of compressed air over time, helping with leakage detection, compressor sizing, and energy optimisation, ultimately using the data to make the right decision about the ongoing operations future expansion of the system. Whether compressed air users, air compressor suppliers, service teams, or operators – we can all improve the energy efficiency, system efficiency, and costs by looking beyond system efficiency to optimise compressed air demand and supply. The added benefit of this approach pays off by safeguarding your assets, reducing the risk of downtime and maintaining efficient operations. www.elgi.com 40 HYDRAULICS & PNEUMATICS September 2022 www.hpmag.co.uk