A new digital automation system recently commissioned at the Ataka power station in Egypt is expected to minimize outage time and provide a number of benefits, including greatly improvedproductivity and enhanced reliability.
Denis Lawlor, Emerson Process Management, Pittsburgh, Pennsylvania, USA
Tower station, located in the Suez region of Egypt, was built in the early 1980s using German and Austrian technology and a Siemens control system. The four units at Ataka comprise two 150 MW units and two 300 MW units to give a total generating capacity of 900 MW, enough to supply power to four million residents.
The control and instrumentation system at Ataka had served the company well but with some of the equipment approaching 25 years old, there were growing concerns about the availability of essential spares and the increased risk of unscheduled shutdowns. The management team at Ataka were aware of the many benefits that the latest digital technologies could provide, and started to plan a major system upgrade for the whole site. In 2002, the East Delta Electricity Production Company (EDEPC), the owner of Ataka power station, secured funding from the US Agency of International Development (USAID), for upgrading the instrumentation and control systems on the site.
The Ataka thermal power station in the Suez region of Egypt, has a capacity of 900 MW
The main objectives of the upgrade were to increase the overall plant efficiency, improve availability and reduce operating costs. The new system needed to be flexible and accurate, integrate control and data acquisition, provide detailed diagnostics and monitoring for faster identification of equipment problems, and enable an easy upgrade route. This meant replacing the obsolescent and unreliable equipment with a digital plant architecture using the latest intelligent devices and high speed communication networks.
After reviewing the bids of several vendors, the $16 million contract to modernize the Ataka power station was awarded to US company, Emerson Process Management in May 2003.
The modernised control room at Ataka displays the process control systems enabling the operators to monitor and control the plant
“The Emerson solution was able to meet all of the objectives we had set for the project,” said Mohamed A. Hassan, chairman of the East Delta Electricity Production Company. “The Ovation control system is optimized for the global power generation industry and this was a significant factor in our final choice of system supplier. Emerson was also able to demonstrate considerable power industry expertise and has successfully completed a number of large projects in Egypt including Shoubra El Khima, Damietta combined cycle power station, El Arish, Cairo South and El Kureimat power generation facilities.”
Emerson served as the main automation contractor for the instrumentation and control modernization project with responsibilities that included engineering design, equipment and instrument procurement, control system upgrade, site installation, commissioning and start-up. Emerson’s Power & Water Solutions industry centre was to co-ordinate and supervise the project.
Equipment and architecture
Emerson’s PlantWeb, digital plant architecture serves as the technology foundation for both asset optimization and process automation, combining smart field instrumentation and analytical software with a strong distributed control system to optimize plant operations.
The use of digital plant architecture at Ataka has minimized outage time and enabled project automation costs to be significantly reduced. These savings result from reduced specification and procurement costs, material and labour savings, smaller control room footprint, and streamlined design and engineering.
As a key component of the PlantWeb architecture at Ataka, Emerson has installed an Ovation expert control system. This includes a multi-network architecture with four redundant unit networks and one shared LAN. The architecture enables full communication between units without compromising security.
Ovation provides optimum control for many areas at Ataka, including unit coordinated control, boiler management system, combustion control, balance of plant, data acquisition, automatic turbine startup, steam turbine control, reheat steam control, boiler feed pump control, and auxiliaries control.
Ovation incorporates embedded advanced control algorithms specifically tailored to meet the challenges of electricity generation; a mission-critical, fast ethernet network with a 100 000 points/s capability; a powerful controller; and a full line of analogue, digital and special-purpose turbine and boiler control modules.
The major digital automation system for each unit includes redundant Ovation controllers, a database server, an enterprise historian, three operator workstations, one AMS Suite workstation and one Global Performance Advisor workstation for performance calculation. The SmartProcess Global Performance Advisor allows operators to identify controllable losses, track equipment performance against design specifications, and quickly identify problem areas to reduce operating costs.
Rosemount pressure and differential pressure transmitters
Emerson also upgraded much of the existing field instrumentation. The new instrumentation can be communicated with remotely by using AMS Device Manager that is integrated with Ovation. Instruments such as transmitters and analysers, valves and fuel oil flow meters are equipped with “smart” processors and the AMS software enables instrument operating data to be captured and made immediately available to the instrumentation and control maintenance team. By identifying and rectifying faults before they escalate into problems that could cause an unscheduled shutdown, operational efficiency has been improved.
The existing Ataka control panels and benches in the control room have been replaced with a modernised control system and latest control technology This includes 13 dual operator workstations, five single workstations and four large screen alarm displays. All the Ataka plant process control systems are depicted on the display graphics to enable the operators to monitor and control the plant. The new system has greatly improved productivity and reliability at the plant to levels that have never been previously achieved.
Due to the high electrical power demand from Egyptian consumers, particularly during the hot summer months, it was not feasible to shutdown all four units simultaneously. A sequential schedule was therefore developed with a 12-week outage period allowed for each unit to minimise the impact on the generating capacity of the plant.
As part of the requirements of the USAID funded project, Worley Parsons based in the USA, was commissioned to review the engineering design and project schedule to ensure the contractor followed the project’s technical and contractual requirements as well as USAID’s regulations.
The engineering design phase started in August 2003 and took a year to complete. This phase of the project was made more difficult because of the difference between units 1 and 2 (rated at 150 MW) and units 3 and 4 (rated at 300 MW). To reduce the impact of unit outages, the new system had to be designed to allow one unit in each pair to be upgraded individually and this added another layer of difficulty for the contractor.
Ataka unit 3 was the first unit to be scheduled for outage starting in September 2004. It reached synchronization in January 2005 and successfully completed a three-week reliability test.
As part of the project implementation services provided to Ataka, Emerson defined system acceptance tests and built a first order ‘tieback’ process simulation model so that the project engineers could benchmark their integrated application against a live process. This was used for logic and modulation control tests and significantly reduced project on-site startup time. The simulator was also used for training, which enabled the operators to experience the feel and response of the system before going live.
Unit 4 was the next to be placed in outage for upgrade starting on March 5, 2005. With the benefit of the experiences gained on unit 3, work on unit 4 was completed more quickly and it was synchronized on May 4. Unit 4 also successfully passed a three-week reliability test on June 1, 2005. Commercial operation of units 3 and 4 started in late January and early May 2005, respectively.
The refurbishment then moved on to units 1 and 2 with Ataka unit 1 starting its outage on July 3, 2005 and being synchronized on September 16, 2005. Unit 2 was shutdown at the end of July and was successfully synchronized on October 8, 2005. Both units have successfully completed three-week reliability tests and are in commercial operation.
“We are very satisfied with the way that Emerson has approached this large project,” said Hassan. “Emerson is a well established supplier with extensive experience in the power industry, and with its range of leading technology solutions, the Emerson approach represented a low risk option for the Ataka upgrade. We have been impressed with the accuracy of the planning and scheduling during the project, and we know Emerson can be relied on to complete work on time. Co-ordinating the programme between the owners, USAID, and Worley Parsons was an important aspect of the project and we have enjoyed a high level of co-operation and open communication.
Rosemount pressure and differential pressure transmitters with manifolds linked to process with impulse lines
Hassan continued, “PlantWeb has allowed us to keep the outage times to an absolute minimum, and now that the units are back on line, we are already seeing significant operational benefits. The digital technology provides information that shows exactly what’s happening in the process; it helps predict and identify conditions that cause variability, and provides access to information whenever and wherever it’s needed.”
The on-line monitoring and diagnostics help to detect and avoid causes of equipment failure that can expose personnel to unnecessary risk and can lead to unplanned downtime. They also help improve control and maintenance, for shorter, less frequent planned downtime and faster startups after shutdowns.
Commenting on the successful completion of the project Mr. Hassan concluded, “We are delighted with the performance at Ataka following the upgrade. As an example of the many benefits that the new digital architecture has provided, we have experienced a significant improvement on the unit startup time and are already seeing an improvement in efficiency on units 3 and 4 of approximately 1.5 per cent, representing fuel savings of 1 per cent.”