Articles & Case Studies


Posted: Wednesday 13th October 2010

PCS7 makes its mark as United Utilities see cost and efficiency benefits on waste pipeline network, courtesy of newDCSplatform.

In today’s highly competitive business landscape, doing ‘more for less’ is the name of the game for many businesses, and competition is certainly fierce in all sectors of the energy industry. Companies need to see how and where they can address costs and increase daily operational efficiencies.

Seeking a way to reduce operational expenditure and increase operational efficiencies lay at the heart of a major United Utilities project to upgrade a 40km wastewater biosolids pipeline and pumping station network serving large areas of theNorth West. The company looked to expert assistance through its framework partner Siemens to help it improve the control and management of the volumes of waste being transported through its pipe network to a central processing centre - as well as underpin a business need to augment capacity so it could safely and effectively transport and treat expected increasing raw waste volumes in the future.

Collaboration with Siemens Industry Automation has seen the implementation of a new automatedPCS7 distributed control system (DCS) across the length of the pipeline – a system that is now delivering a range of benefits for United Utilities. The provision ofDCSto monitor the whole catchment, along with some plant and process improvements will achieve a 40-50% reduction in operational expenditure per cubic metre of raw waste treated - at the same time as increasing its processing capacity. This single process control platform provides accurate ‘real time’ pipeline performance data analysis and reporting, reduced unplanned maintenance occurrences, enhanced self-diagnostics, improved visibility of the entire pipeline network, and forms the foundation for further planned process enhancements to the daily operation of handling and treating biosolids from a regional population of over 3.5 million people.

United Utilities is the UK’s largest listed water company who own, operate and maintain utility assets, including water, wastewater, electricity and gas. At the centre of the upgrade project is the Mersey Valley Sludge Pipeline, a 40km pipeline network which handles raw waste across the North West region ranging from Liverpool to Oldham. The sewage pipeline feeds into the central Mersey Valley Processing Centre (MVPC) at Shell Green in Warrington and it was a need to better understand and manage the control and treatment of the waste to the centre that underpinned United Utilities’ desire to seek a new process control solution. By doing this the company believed it could address overall operational expenditure levels.

The Shell Green processing centre handles up to 87,000 tonnes of biosolids waste per annum with the treated waste either ending as material for export for agricultural purposes or incineration to produce a sludge cake substance for use in landfill.

With the processing centre receiving incoming waste from a number of separate feeder sites along the entire length of the pipeline, the quality (% dry solids) and age of the biosolids being transported and treated was of primary concern, as it has a considerable effect on the cost to pump and treat. United Utilities management at the central processing centre required a better prior understanding of the consistency of the raw material it was about to receive, so that it could improve the management of the sources of the biosolids waste.

Homogenous consistency of the feed stock or raw materials sent to the processing centre is very important as it directly influences the efficiency of the operations at Shell Green. If raw materials are either too thick (compact) or too thin (watery), it means that the treatment process of the waste - such as dewatering the material -can lead to significant additional expenditure. In the incineration process, for example, if the material is too wet when entering the process it will require additional energy resources to reach its optimum auto-thermic state. In such cases, United Utilities are exposed to additional operational expenditure through higher gas consumption.

The solution provided by Siemens to help bring the processing centre under greater control involved the generation of a PCS7 distributed control system for the pipeline and pumping station network. This provides a single and consistent DCS platform across the length of the pipeline linked to the processing centre so that through control, monitoring and accurate reporting greater efficiencies could be achieved. Previously, the central processing centre had to deal with the varied feed stock it was sent - often without warning. The new control platform now allows the centralised operational personnel to identify the consistency of the raw materials at a much earlier stage along the pipeline and then use real time data and analysis to decide the optimum way to treat it.

The DCS system, through this early material identification, provides management with remote visibility of the performance of each of the distributed donor sites that feed into the pipeline. With closer control, more accurate decision-making can be taken concerning the materials being sent along the pipeline before it reaches the MVPC. In essence it provides the information to get it right first time.

Two other critical features of the DCS system have also supported United Utilities in their objective to improve its OPEX commitments. Firstly, the implementation of a DSL wide area network with VPN technology as part of the solution so that improved connectivity is built into the DCS platform - as opposed to the previous reliance upon leased lines – has provided real benefit. This connectivity ensures that the operational management has accurate and timely information at their disposal in order to make decisions. Likewise, access via Profibus technology to the performance of the remote sites has vastly improved the ability for self diagnostics and had a real impact on what has been costly maintenance commitments.

Traditional high maintenance spend is being turned on its head as a programme of predictive maintenance has been put in place courtesy of the visible diagnostic sequence steps available via the DCS platform. Indeed, United Utilities expect the majority (80%) of it maintenance commitments across the pipeline to switch to planned/proactive nature by 2012, as opposed to just 10% in 2009. Planned or predictive maintenance brings with it cost savings, improved critical equipment reliability and better overall plant availability as previously undetected issues are dealt with on a proactive basis before they can interfere with day-to-day operational performance.

It is clear that the DCS platform is now delivering real and quantifiable benefits for United Utilities. At the start there were a number of challenges to this project, including the need to reduce OPEX at the processing centre; trusting a new and different technology as the DCS solution is vastly different to the traditional SCADA platform; the ability to integrate the various elements of the control platform without affecting the day-to-day operation of the pipeline and processing centre, and the proposed use of VPN technology as a reliable source of data transfer especially for reporting needs.

The challenges have been met and the DCS solution supports the central objectives set for the project - which was to improve OPEX performance, whilst seeking to improve the overall ability to handle increased volumes of raw waste over the short and long term. Better process control and enhanced reporting provides better knowledge and operational flexibility, which in turn supports operational performance improvements.

As a result of the pipeline upgrade United Utilities has re-designed its processes which have directly led to measurable reductions, for example, in its overall energy use, as well as levels of chemical procurement needed as part of the treatment process at the centre in Warrington. It now boasts a single, more reliable hardware solution that will provide 15 -25 years of fully supported performance capability. It has also give the company a solid foundation for additional project enhancements which will allow it to continue to service the needs of the many millions of people the Mersey Valley Pipeline and Processing serves.

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