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Integrated engineering: Optimising the safety and efficiency of Energy from Waste plants

Author : Steve Leech, Product Manager, Siemens Industry Automation

02 October 2013

All plant owners, engineers and operators seek methods to reduce risk, increase operational efficiencies, shorten time to market and continually optimise processes.  An integrated engineering link from plant concept to ownership – the digital plant – is set to help satisfy such objectives. With a long-term vision of reducing product launch times by up to 50%, and plant design to construction timescales by over 10%, the advantages of digital plant could deliver clear benefit to importan

The Energy from Waste market is growing fast
The Energy from Waste market is growing fast

Any new plant development faces a number of key challenges.  These will include a requirement to have the plant delivered and up and running without undue delay, as well as important ongoing factors such as optimising the plant performance through its lifecycle by reducing risk and maximizing operational efficiencies.  Both these factors will also impact the ability of plant operators to shorten time to market and offer enhanced product launch times so that investment cycles can be supported.

Central to meeting these typical challenges is the ability to create an efficient plant engineering environment from the original concept of the plant through to its operational ownership.  Traditionally, the various elements of plant design, engineering, commissioning and optimisation have acted in isolation of one another, which due to its serial structure often meant delay as one stage was completed before the next got underway.  The need to link such vital stages in an integrated manner lies at the heart of meeting the challenges presented by efficient plant engineering.  Such integration is now made possible through the concept of the digital plant.

The thinking behind the digital plant is a fusing together of the various elements – from design software to the engineering tools that are integral for the concept, build and operation of any plant.  To enable this now to happen, for the first time, the market can benefit from an ability to utilise integrated engineering solutions that can seamlessly link the upfront plant design, engineering and commissioning phases with the ongoing daily operational and future plant optimisation stages.

The fusing of COMOS plant engineering software - intrinsic in the plant and process planning stage - with the operational plant operation control delivered by PCS7 provides a number of real advantages for plant owners, engineers and operatives.  It provides a consistent plant and equipment engineering environment in a two-way process that sees, for example, code generated in the COMOS operated design stage seamlessly transferred to the PCS7 operational phase.  In essence, it becomes a living system and is an ‘as built’ plant from day one which can offer a two-way data exchange.  It negates the requirement for multiple inputs for changes at any stage and creates a scenario that mitigates the undoubted risks associated when system alterations are made.  In effect, changes made in one part of the process simply ripple through to the other – alleviating repeat tasks and reducing risk.

The integrated engineering approach is best illustrated by the ability to enjoy a continuous information flow from product design to production.  It is based upon an integrated tool chain including all the key stages from plant design, through basic engineering, detail engineering, installation and commissioning, and final operation and maintenance. Engineering workflow uses a single engineering model for all aspects of the plant, I&C and automation configuration.  

In terms of having a plant up and running and making inroads into the substantial financial investments made by owner/operators, it is possible by adopting such an integrated approach to reduce the plant concept to commissioning phase timescale by up to 11 weeks and the number of man-weeks involved by approximately10%.  This, by definition, provides substantial gains in both efficiency levels and cost reduction targets for any proposed new plant.

While the integrated plant engineering phase boasts the ability to optimise the engineering process, reduce process lead times, reduce risks and shorten development times, similar benefits can be derived from an integrated plant operation standpoint.  Once in operation, users can see the advantages of closer fusion between the engineering and operational functions; minimised plant downtimes and shutdowns, fast and error-free information handover as data is exchanged seamlessly and consistently available plant documentation.

Tilbury power station - Photo: Danny Robinson
Tilbury power station - Photo: Danny Robinson

Energy from Waste – a plant template for the future?

By 2020 a quarter of the UK’s existing power generation capacity will be gone and significant investment in affordable low-carbon power is required to bridge the generation gap.  It is estimated that renewable power will contribute 15% of the UK’s energy consumption by the end of this decade creating demand for energy from waste solutions.  

The Energy from Waste (EfW) market is growing due to pressure for new plants to help tackle the legislative pressures on local authorities for sustainable waste management strategies, as well as their potential role in alleviating the growing power generation gap.

For plants that will have to operate efficiently for up to 25 years, the integrated design, engineering and operational approach outlined above should help support what is set to become an increasingly important UK industry sector as the new century evolves.  

Hazards relating to Energy from Waste plants

From a safety perspective EfW brings a number of challenges.  A serious fire at Tilbury power station back in February 2012 demonstrates only too well that the feed material itself can present fire hazards. At Tilbury the fire was caused by an external ignition source but biomass also has the potential to self ignite if stored in the wrong conditions so safeguards related to storage need to be put in place and mitigation such as fire systems needs to be considered. Dust explosion hazards can exist so the DSEAR regulations apply, along with a requirement for hazardous area classification.

From a process safety perspective the hazards involved differ depending on whether pyrolysis, gasification or incineration processes are being used, but include high temperature, high pressure and the presence of flammable “syngas” as an intermediate.

The Integrated Engineering concept
The Integrated Engineering concept

Explosion hazards, fire hazards and the risk of asphyxiation and toxicity associated with unplanned release of hazardous gas and liquids make it extremely important that the safety issues of EfW plants are properly addressed. 

How the digital plant concept helps from a safety perspective

The digital plant concept relies on a single central database linking together all the various stages of engineering and operation.  Safety can be more effectively addressed throughout all stages of the plant’s lifecycle by having key safety data integrated into this common database.  The HAZID and HAZOP can be facilitated and documented in the plant design and P&ID modules of COMOS and, if required , Safety Integrity Levels (SILs) can be assigned to Safety Instrumented functions (SIFs). COMOS can also help with meeting the DSEAR regulations and can be used to consolidate ATEX related information for plant items in the hazardous area. 

The consolidated approach to data helps ensure that all stakeholders have access to accurate safety data when needed.  HSE studies indicate that errors associated with accidents caused by automated control systems are introduced at all stages of the plant lifecycle but over 50% are in the specification and design stage.  An integrated approach from plant design and process engineering through to the detailed engineering of automation and safety instrumented systems helps avoid such errors and thus improve safety in all stages of the plant lifecycle.  

Integrated plant design, engineering and operational tools can offset the concerns of energy from waste plant owners wishing to commission a substantial piece of construction without delay; plant engineers charged with its design and build as efficiently as possible,  and operators tasked with effective long term operation, maintenance and control of the plant.  

So-called ‘digital plants’ offer the realistic template for the future.  Software-driven, seamless links between concept and operation stages provide the assurance of proven risk reduction in the engineering phase through the non-repetition of tasks, as well as a rapid shortening in the crucial plant design phase.  

The operational benefits of having an ‘as built plant’ from day one with intelligent data available from the start of operations to underpin operational efficiency gains, and a standardised approach to software and control technology that future proofs the plant through its lifecycle, are all clear evidence of the competitive advantages seamless integration for plant design, engineering and operation can bring. 

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