Product category:
Asset Management and maintenance planning
News Release from: Emerson Process Management | Subject: Emerson Performance Services
Edited by the Processingtalk Editorial
Team on 30 December 2002
Interrogation highlights poor plant
performers
Emerson Performance Services is a skilled consultancy service, created to help customers gain the benefits possible from asset optimisation, using the power available within intelligent field devices.
It is well known that intelligent field instruments - valves, transmitters and analysers - use modern digital communications to transmit information all around a plant on standard protocols like Foundation fieldbus and Hart These instruments deliver far more information to the plant engineer than was ever thought feasible: and it is certainly more than can easily be understood and monitored
This article was originally published on Processingtalk on 29 Aug 2008 at 8.00am (UK)
Related stories
Emerson releases AMS Suite
Emerson Process Management has announced AMS Suite: Intelligent Device Manager 9.5 applications for planning and managing scalable wireless networks to support the process automation industry.
Emerson opens offshore engineering centre
Emerson Process Management has announced the opening of an engineering centre in Oslo, Norway.
There have been significant benefits to plant engineers in using this technique to collect and present calibration record data, for example: this saves time and paperwork.
Also maintenance records can be held and accessed from the equipment itself.
Performance warnings or maintenance reminders can be generated on the same system, allowing plant engineers to monitor the opinion of the instrument itself about how well it has been performing: this is asset management.
Further reading
Emerson improves oxygen analyser
Emerson Process Management has enhanced its Rosemount Analytical X-Stream oxygen analysers to improve efficiencies of large boilers and furnaces.
Emerson new Micro Motion Coriolis transmitter
Emerson Process Management expand range of compact Micro Motion 2400S transmitters with 316L stainless steel housing as an option to the standard polyurethane-painted aluminium housing.
Emerson to automate coal-fired power plant
Emerson awarded contract to digitally automate PLTU 2 Banten-Labuan coal-fired power plant in Indonesia.
But a major function of PlantWeb digital plant architecture, where everything is linked and monitored across the same network, is to be able to monitor overall process performance, typically via inspection of individual control loops, to identify when devices require further troubleshooting or maintenance: this is moving further towards the goals of predictive maintenance, and overall process performance improvement.
The term currently adopted for this idea is "asset optimisation", because it is using the expertise of the software tools available to ensure that plant assets are run at their best efficiency level, both in their own maintenance environment and in the way they are interacting with other equipment within the process.
The experts in the use of the software programmes that are accessing this information, in order to identify potential improvements in plant and asset performance, are at present concentrated in the control system software suppliers themselves.
These are the people who are using the techniques every day, and have an input into the software development as well, to expand the science of monitoring processes, monitoring how small changes in valve positions affect all other sensors, and what this tells about the underlying process.
Significant software development work in this field has resulted from the systems analysis undertaken by Emerson Process Management, because its product range covers the whole control scene, using sensors for flow, temperature and pressure, valves to control flow rates and pressures, control function blocks within valves or sensors, process fluid composition sensors and analysers, and also condition monitoring systems like vibration, rotation speed and oil analysers.
The software being produced pulls this expertise together: but while asset optimisation is still a new technology, it tends to need a software engineer to drive it.
To make such software expertise available for actual industrial situations, Emerson Performance Services has been created as a skilled global service consultancy organisation, to assist customers gain the benefits possible from these new tools.
As well as hopefully improving plant performance on each project, these engineers will also be involved with training the customer's own plant operators in the use of these new software tools, and in the process themselves learning more about how plant components interact.
Typically these consultancy projects sort out loop performance problems that the plant engineers possibly knew existed (from their innate "feel") but could not quantify, and did not have the detailed understanding of the software tools available within their control systems, to interrogate this aspect of their plant themselves.
The engineers involved in the Performance Services team mainly use the standard software available to all plant operations staff within the AMS (asset management solutions) system, typically programmes called ValveLink, LoopScanner or FlowScanner, to analyse plant control performance from the loop level upwards.
The most effective route to plant optimisation always starts at the loop level.
By reducing process variability at loop level, and increasing equipment reliability and stability, the plant is driven towards the most efficient working profile.
The following examples of the application of these techniques show what can be done, and how straightforward a complex problem can become once analysed.
Two of the examples happen to relate to electricity power generation plants, and one to a chemicals plant, but the results are generally applicable across other industries, when the base element analysed for these cases is a control loop.
At major UK power stations, turbine shutdowns are scheduled for maintenance at planned time-slots through the summer months.
This is a time of high activity for all instrument and valve maintenance people, and advance planning is essential.
As a trial to look at predictive maintenance techniques, Powergen invited Emerson Performance Services to demonstrate its FlowScanner diagnostic system on valves and controllers on one of the turbine generator units at Ratcliffe-on-Soar Power Station, to determine which valves were in need of stripping down and refitting.
The FlowScanner software system is a portable, in-the-field way to investigate the operating condition of a control valve, using information available over the plant control system, producing results very similar to the data provided by full factory "signature series" tests.
If carried out on a regular basis these signatures can be compared over time, and wear rates monitored remotely.
The FlowScanner tests do not require the valves to be fitted with intelligent valve controllers, such as the Fisher DVC5000, but if these are fitted then much more operational historic data is accessible.
After 3 days on site, the FlowScanner test results obtained by the Emerson Performance Services engineers showed that just three of the 16 valves on one generator required stripping down for overhaul.
As the valves checked were around the HP heater and gland steam systems, maintenance requires erection of scaffolding and removal of insulation, as well as valve removal and overhaul.
Cost for the overhaul work on three valves only was ?2500, plus ?1000 for scaffolding, removal and re-insulation on return to service.
The previous overhaul costs for the full 16 valves had totalled over ?18000, therefore the savings more than covered the cost of the FlowScan survey work.
Overall saving to the plant for one generator turbine valve survey and the resulting recommended maintenance was ?12,900.
Subsequent tests will have the benefit of the data from the current set of tests, to allow comparisons and monitoring to identify any valves subject to higher wear rates than average.
Barking Power Plant, a modern 1000MW gas fired power station which uses advanced combined-cycle technology, had experienced some oscillations in the gas stream supply pressure at the turbine.
Such supply instability increases the workload of individual turbines, therefore increasing the wear and maintenance activities needed on them.
In addition, under varying plant load, the oscillations were amplified, and had led to occasional plant trips.
Thames Power Services manage the plant operations, and called in Emerson Performance Services to carry out a loop performance audit on the main gas supply stream.
Using the Fisher LoopScanner system, the control valve itself was identified as the main contributor to the process variability - poor performance from this valve accounted for 70-80% of the total problem.
Following replacement of the old valve controller by a Fisher DVC5000 FieldVue digital valve controller, the process variability was reduced by 50%.
The power station immediately saw a marked improvement in the plant performance in terms of stability.
Further work is planned during the next turbine shutdown, when it will be possible to optimise the loop tuning constants.
The engineers at Thames Power Services is convinced that this will lead to a reduction in the maintenance requirement, and improve plant life.
Plant availability and efficiency will increase because of a reduction in unscheduled plant trips.
Already they are re-evaluating the required maintenance intervals, because of the smoother plant running.
Total savings expected will be in excess of ?80,000, a significant sum.
Similar process performance investigations will now be carried out in other areas of the station.
Emerson Performance Services was asked to investigate a production variability problem at a manufacturer of carbon black.
This is an intensely black powder, that functions as an indispensable reinforcing or pigmenting agent in a broad range of products.
It is produced by subjecting a heavy residual oil feedstock to extremely high temperatures, in a carefully controlled combustion process.
There are many different commercial grades available, each having a characteristic particle size and structure, produced through minute and exact adjustments to the reaction process.
It was therefore difficult to maintain the grade of product required when the operators experienced a degree of variability in the main feedstock flow to the production reactor.
These changes had a significant impact on the product quality, and plant output, so that further investigation was a high priority.
Several actions had been taken to ensure that all the key control elements were working to the highest standard.
Though this reduced the problem, it was felt a more detailed analysis of the loop performance was required.
A full loop performance audit was carried out using the Fisher LoopScanner software system.
This is used to gather real time process data, from which analysis can identify the root cause of process variability and recommend the necessary corrective action to reach optimum performance.
In this case the analysis suggested that the source of the variability was located either in the control system I/O cards, or the earthing system.
The site engineers focused their attention in more detail on this area and found a possible problem with a backup power supply.
Wiring corrections were made and there was an immediate performance improvement - data collected on a subsequent loop test showed a 35% reduction in flow variability.
To quantify this result in business terms, the plant operators estimated a minimum of a 1% improvement in first pass yield: this leads to a reduction in the volume of material requiring recycling by 190 tonnes in a year, representing a plant cost saving of ?30-40,000.
Costs were ?3000 for the Emerson Performance Services loop investigation, and ?2000 for plant operating personnel costs and resources used.
There was no major further investment, the conclusion, as often, was a simple correction which had evaded attention until the particular area was identified.
The examples quoted above used on-site investigations by Emerson Performance Services engineers bringing the investigation software to the plant, to plug into the existing control system.
The inevitable technological developments, avoiding the costs of site visits and difficult on site access, is already taking place: internet web access, already used to reconfigure equipment on gas analysers up flare stacks, is allowing the same engineers to use phone lines to access the control system.
Just as plant processes can be reconfigured using a modem, interrogation software can be used to investigate each loop remotely, and identify the areas for on-site engineers to look at more closely.
The next step is performance monitoring of critical plant areas, by having extra sensors linked into the control system, allowing remote external service providers, such as the "e-fficiency" service from Emerson Process Management, to produce regular performance analyses and maintenance recommendations. Request a free brochure from Emerson Process Management ...
• Emerson Process Management: contact details and other news
• Email this article to a colleague
• Register for the free Processingtalk email newsletter
• Processingtalk Home Page
Search the Pro-Talk network of sites
