Control project improves boiler efficiencies

Experienced boiler and energy plant operations and maintenance service provider Associated Energy Services (AES) is currently monitoring the performance of a recently completed project that included programming and control system intervention as well as the upgrading of a boiler control system for a fast-moving consumer goods client.

AES commercial director Dennis Williams tells Engineering News that the project – completed between March and April – was aimed at “tightening the boiler steam pressure control through adjustment of the control system, so that the boilers balanced the load automatically between the online boilers”.

“The client’s steam demands are variable; therefore, a change in steam demand requires critical distribution across the multiple boilers on-site to maintain a stable steam pressure and optimise the steam efficiency on each boiler.”

He adds that AES was responsible for all the hardware, programming, integration and commissioning of the units; and also completed the upgrades on the control systems.

“We had to create a bespoke solution, as an existing, off-the-shelf one did not exist. We were able to create this solution through our experience, regarding both hardware programming as well as operational experience in bringing the required technologies together in a holistic, integrated solution.”

The company implemented a secondary control loop to monitor individual boiler conditions. Additionally, the control philosophy – which was designed by AES’s in-house instrumentation engineer and technical director – strategically manages the individual boiler loads to achieve load balancing, while still ensuring the steam demands of the production plant are satisfied.

“Previously, the steam pressure trace had varied across a much wider range, so we were tasked with ensuring that the steam pressure trace was as stable as possible, and to create a very tight degree of control.

“We also needed to ensure that the induced-draught fan percentages – which indicate the operating load of the boilers – were closer in grouping and were more coordinated. This is because, previously, there had been large loading differences across the various boilers, indicating that the load was not being proactively shared in a manner that could support stability.”

The upgrades improved efficiencies, with the more stable steam pressure enhancing steam processes and the better-balanced loads reducing fuel consumption.

“The upgrades achieved about an 80% to 85% reduction in steam pressure variation on stable operating loads, compared with the unbalanced system, as well as a 60% to 70% improvement in boiler load balancing.”

Notably, the project was commissioned and rolled out without interrupting production.

“Safety integration into the overall system was also a major consideration. Fortunately, the engineering and mission-critical staff at this site have a strong understanding of the required safety and efficiency-related aspects,” states Williams.

Keep the Plant Boilers Burning

AES, as part of its extended period of commissioning, is using its remote monitoring system (RMS) to track the project’s ongoing status and progress.

“The system is a bespoke solution and, as such, requires monitoring for a certain period, to see whether adjustments are needed. It is, however, currently operational and delivering,” says Williams.

Moreover, the RMS is of great benefit to the client as it makes it very easy to see the ‘before and after’ effects of the project.

Williams notes that AES had completed an upgrade on the client’s boiler house some nine years ago and that AES’s strong relationship with the client, including its existing presence on site, and shared overarching boiler control philosophy, presented numerous advantages.

He suggests that, while an external provider would present a solution and then walk away, AES, in contrast, is there post-implementation, to continue operating the system and make sure that the operational benefits are delivered.

“AES is running the plant 24/7 and is proving that the solution is working, using its RMS.”

In addition, better long-term fuel efficiency is a tremendous benefit to the process plant, its productivity and, by extension, its profitability.

“Ensuring that the boilers operate in a more stable and balanced manner contributes, in turn, to significant operational efficiencies,” stresses Williams.

Other Work

Williams avers that, given the current local power crisis, the ability to maximise productivity in the manufacturing sector is critical; fortunately, AES can offer tried, tested, and “highly successful” solutions.

He cites an existing client in the food industry for which AES assessed multiple different technology and fuel options.

“AES was tasked with looking at the client’s current and future steam requirements. The client had specific objectives and timelines regarding its greening and decarbonisation objectives. It also understood the challenges around implementing a 100% renewable-energy solution, in a South African context, and was happy to follow AES’s guidelines.”

He notes that AES helped the client review the specific operating and capital costs for each possible fuel type and technology solution. The company then compiled a comprehensive report, giving input around the specific risks and benefits of each fuel and technology solution; the operating costs; and some strategic aspects of each fuel type, such as, for example, carbon tax requirements and a possible reversal of current rebates.

Williams says the client ultimately elected to use a timber residue biomass solution, with AES currently developing final capital expenditure proposals, so that the project can go ahead.

AES has been assisting industrial plants with energy best practices for over 25 years, operating across a broad range of industrial sectors, he concludes.