How to bank on plant efficiency gains

As more energy recovery facilities come on stream, Simon Ellam highlights the need for standardisation in process control so operators can boost productivity

Energy-from-waste (EfW) covers a number of diverse process technologies such as gasification, pyrolysis, and anaerobic digestion, as well as other emerging technologies, which are at the heart of a number of package plant deliverables such as material handling and treatment infrastructure.

This modular approach can often pose a major challenge for the engineering, procurement and construction (EPC) contractors and plant operators who are looking to engineer a coherent control system that will allow efficient running of the complete plant. The challenge of co-ordinating how package plant is controlled and bringing a degree of standardisation across the different deliverables falls mainly to the EPC or main contractor involved.

However, increasingly the end-customer or plant operator involved is not prepared to accept a disparate control strategy as they typically have to live with this for the 25-year plus asset life of the plant. The answer lies in the provision of a standardised approach to technologies that incorporates open standards and protocols. This solution underpins the task of engineering and connecting ‘islands of automation’ together. The hardware aspect is the most obvious, but only the first benefit of having a standardised approach to engineering.

Automate to acculumate

Process automation comprises a number of control system solutions including distributed control systems, programmable logic controllers, fieldbus networking along with all the peripheral equipment that allow these control systems to give optimal control of a customer’s assets. The key aspect of such a broad portfolio of potential solutions for EfW is the ability to offer sound engineering advice that fits the varied technical and organisational models that have emerged within this market.

A good example of this is the growth in PFI-style contracts as local councils seek to outsource the design, manufacturer and operation of a plant on their behalf for 25 years. This type of project is typically contracted to a consortium, or alliance of suppliers, who possess the combination of requisite skills from initial design to de-commission.

There is increasing focus on efficiently integrating the elements of ‘packaged plant’ while combining this with a longer-term view of optimising operational costs over the ownership period.

With this in mind, the second and most important phase of standardising the process solution in an EfW plant is to achieve the same look and feel of application or operational display that the operator uses to monitor and control the plant. This allows operators to gain a quick understanding of how to control plant and, if a co-ordinated approach has been achieved in the design and build phase, the operator will not need to manage different skill sets to operate different areas of plant.

Operational benefits

This standardised approach brings huge operational savings and allows the flexibility of operators and shifts to be applied to different roles without upheaval. A poorly conceived plant control system will create complexity, leading to increased labour requirements and dependence on higher skilled labour, plus reduced plant control and flexibility, leading to higher consumable/energy costs and poor asset utilitisation.

Generally the contractual relationship between the owner/operator of these plants and the end customer is tied into their ability to serve and to environmental compliance. This requires the site control system to offer a high level of availability and the ability to constantly monitor and adjust/optimise the process to give the lowest running costs, while achieving environmental compliance targets.

There is no doubt the EfW market is proving to be more sophisticated in its ability to drive for profitable operation. Most contractors taking on design, build and operate contracts such as those found in the EfW market are now attaching much higher importance to this category of supply. This approach really can mean the difference between a long-term success and a long-term sentence.

Simon Ellam is business manager for the process automation division at Siemens

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