Businesses worldwide face the dual challenge of rising fuel costs and environmental energy taxes; there has never been a more critical time to focus time and effort on reducing utility costs.
For the efficient management of plant operations, the critical considerations for the energy manager include product quality, safety, downtime, and of course, energy use. A food and beverage production plant in Germany has set a greenhouse gas emissions reduction goal of 25% by 2030, and turned to the Plant Energy manager to help deliver that target. One way of achieving that goal is to reduce energy use. How can the plant energy manager accomplish this without impacting product quality, safety or downtime?
Reducing environmental impact
Manufacturers worldwide are reviewing the efficiency of operations to reduce costs and drive down their environmental impact. Led by sustainability officers, with the support of energy managers, efforts to lower energy usage are helping to decrease the environmental impact of production, and contribute to global and local efforts to reduce climate change.
In 2011, the International Organisation for Standardisation (ISO) introduced a new voluntary standard for designing, implementing and maintaining an energy management system. A technical committee undertook the development of ISO 50001. Like other ISO standards, it is intended to be realised across various industries and encourages adopters to implement a Plan, Do, Check, Act framework for energy management. Since the Paris Agreement of 2015, the drive for ever more sustainable operations to reduce the effect of climate change has accelerated.
This company is taking a stand against climate change and has committed to reducing greenhouse gas emissions. One crucial programme element focuses on reducing the plant’s indirect emissions from energy use. Specifically, this considers the emissions resulting from the generation of the electricity purchased by the company from its utility provider.
For the bottling plant, one area under review was how to tackle the energy wasted through leaks in compressed air systems. The Carbon Trust estimates that industry in the UK uses over 10 TWh of electricity to produce compressed air, making it the direct root cause of over five million tons of CO2 emissions a year.
Compressed air resource
Approximately 90% of all companies use compressed air in some aspect of their operation, to the extent that it is sometimes referred to as the fourth utility. However, compressed air is often generated onsite, unlike other utilities such as gas, electricity or water supplied to the site by an external utility’s provider. Therefore, the manufacturing companies are responsible for ensuring its efficient production and distribution.
While many people may view compressed air as being as free as the air around them, due to the nature of the process a significant proportion of the energy a compressor uses to compress the gas is lost as heat. Once produced, it is used to automate processes, package products, provide motive power, or generate other gases onsite.
Clearly, the waste of this expensive resource needs to be minimised. The priority is to set up a leak reporting and repair programme. This will give an idea of where the troublesome connectors and lines are sited, and allow a repair strategy to be formulated, to ensure they are kept fully working.
The cost of compressed air leaks
The energy consumption of the compressed air systems at the food and beverage processing plant amounted to R6 million. It is estimated that if there were no maintenance system in place, the losses due to leaks in the network would be between 25 to 30%. Implementing a maintenance regime from this starting point would represent a potential energy cost saving of R2,4 to R3 million per year for the plant in question. While desirable, it is doubtful that any plant will achieve a 100% leak-free compressed air system. The target for good practice for energy losses due to leaks is between 8% and 15%, and actual best practice is 6% to 8%.
Maintenance methods
When looking for leaks, it is essential to remember that some components of a compressed air system are especially vulnerable, for example pneumatic cylinders, flanges, filters, tools, presses and drop hammers, which should be checked first.
Some traditional ways of detecting leaks include listening for hissing sounds, or coating joints with soap and checking for bubbles. The soapy water method is inefficient and inadequate for a manufacturing facility’s size and scope of compressed air lines. Many cannot hear the hissing of air leaks in a quiet environment, let alone a functioning bottling plant. An improvement on the soap and water method was ultrasonic leak inspection.
Ultrasonic tools use microphones to identify the sounds associated with escaping gas in a range of about 38 to 42 kHz. They convert sound captured in this range into audible sound and rely on human hearing to identify whether a noise is a leak. That makes the detection subjective and reliant on enhanced skills and training.
Large manufacturing companies like this one may outsource checks and inspections for leaks in compressed air networks. Specialist companies will carry out annual checks that could deliver what would be considered good practice levels of leakage, between 8 and 15%. However, a new testing regime, less reliant on annual checks through a third-party vendor, was sought by this plant to decrease the energy losses further by reducing leaks in the network.
The food and beverage production plant agreed to test the use of industrial acoustic imagers at the plant to check for leaks in compressed air systems. Recent developments in industrial acoustic imagers, such as the Fluke ii900, mean they are equipped with an array of microphones, providing visualisation of sound field within an expanded field of view that enables maintenance teams to visually locate air, gas or vacuum leaks very quickly and accurately in compressed air systems. This means it is possible to detect leaks even in noisy environments and from a distance, and maintenance programmes can be adopted while the plant is operational.
The detected leaks are then displayed on an LCD display, making it possible for a user with little to no experience to detect leaks immediately. The acoustic imagers can evaluate the distance to the target and estimate the size of the leak, making it easier to prioritise a repair schedule.
Solar loading and wind are environmental factors that must be considered. Solar loading occurs when one or more sides of a structure are uniformly heated by the sun. Similarly, wind moving over a structure can wash away thermal signatures or create unexpected pressure differences, leaving some problems undetected.
The food and beverage production plant has started using the Fluke ii900 to locate compressed air leaks in conveyor systems; tubing, piping, flanges and valves in the clean-in-place system; the syrup maker; and the hard-to-reach gated areas in the CO2 blender.
The equipment is capable of reporting an estimation of the size of the leak. From this data, it is possible to estimate the company’s energy cost and evaluate the return on investment. Crucially, for delivering a targeted reduction in carbon emissions, quantifying the energy lost is an essential feature so that the reduction in greenhouse gases can be calculated. “This innovative technology has excited me from the moment I first heard about it. We have already seen enormous energy savings,” said the plant energy manager.
The future
As energy prices continue to increase, the need to reduce energy costs and deliver on shared sustainability goals intensifies. Many more consumer goods manufacturing companies are taking on sustainability and energy managers to reduce waste and spotlight opportunities to run their plants more efficiently.
The maintenance teams at the plant are vital to the delivery of efficient operations. Using tools such as acoustic imagers that can bring enhanced savings to maintenance routines and reduce energy costs is a quick win for all manufacturing plants with significant compressed air demands.
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