The gain in Spain: Over 0.8 percent plant efficiency boost from digital optimization
With digital optimization tools, power plant operators can gain insight into the thermal inner workings of their assets to improve efficiency and profitability. Endesa’s installation at Alcudia on the island of Mallorca, Spain shows that efficiency gains of more than 0.5 percent are possible.
By Carl Fischer
Like a vintage piano, a power plant that is advanced in years can benefit from a tune-up that optimizes its performance and productivity. With an affordable digital upgrade package from Siemens, the controls of power stations can be adjusted to more efficient settings, allowing them to reach an operational state with higher efficiency and output levels. Asset owners can thus improve their return on investment (RoI) without extensive hardware modifications (which are costly and require major disruptions).
In a competitive market environment, plant operators aiming to get the best possible performance out of their assets – whether in terms of efficient combustion, emissions reduction, or optimizing the functioning of their sootblower – can often achieve tangible efficiency gains from relatively minor adjustments to hardware. Precision laser measurement gives operators a detailed picture of combustion processes as a first step towards getting the most out of their assets, in terms of output as well as profitability.
Digital combustion optimization: Improved boiler settings based on laser measurement
Take the example of the Es Murterar thermal power plant at Alcudia on the island of Mallorca. Its four coal-powered steam turbines and two gas turbines have a capacity of 585 megawatts (MW). Built in the 1980s, the power station provides 70 percent of the energy used at the popular Mediterranean holiday destination, which attracts about 9 million tourists per year. The owner, Spanish energy utility Endesa, conducted a feasibility study to identify ways of controlling and improving the performance of their asset through digital solutions that convert data obtained from laser measurement into knowledge and business results.
“The combustion optimization project is an innovative project, a reference for Endesa worldwide, which combines digitalization with operational efficiency,” says Pablo Gutiérrez, Director of Alcudia. Using the Siemens Omnivise Plant Optimizer solution, based on laser spectroscopy combined with self-learning algorithms, his team was able to capture and regulate processes directly in the combustion zone of unit 4.
“Laser technology enables us to see inside the boiler and monitor our combustion process as well as the distribution of temperature, oxygen, and CO. It also allows us to modify our process online, improving the performance and reducing the number of unscheduled shutdowns,” says Yolanda Lozano, Efficiency Manager at Alcudia.
" The combustion optimization project is an innovative project, a reference for Endesa worldwide, which combines digitalization with operational efficiency "Pablo Gutiérrez, Director of Alcudia
The hardware is easily installed during a brief interruption within about two weeks, when small grooves are drilled into the boiler walls to install the laser spectroscope. Multiple beams are sent through the furnace above the combustion zone and generate readings for temperature, H2O, CO, and O2. The output visualizes the distribution of heat and gas concentrations in the combustion chamber. Based on this data and further process information from the DCS to complete the picture, the Siemens solution modifies fuel and air flows to form combustion for improvements. The solution is closed-loop and continuously interacts automatically with the process. No additional attention by the operator is required, since multiple process limitations are automatically monitored. This controls-based optimization approach, combined with the automatic learning algorithms, provides the adaptability required to handle the variation in burned coal that is common today, as well as other changing process bounds. Endesa and the power plant now have an untiring helper continuously by their side to take action with small and big changes for improved efficiency and better performance.
"Laser technology enables us to modify our process online, improving performance and reducing the number of unscheduled shutdowns."Yolanda Lozano, Efficiency Manager at Alcudia
Efficiency optimization by sootblowing: Improved heat transfer beyond mere cleaning
At the same time, Alcudia’s sootblower also underwent a fine-tuning by Siemens to complement the combustion optimization measures for efficiency improvement. Removal of ash deposits prevents the formation of slag, which degrades heat transfer and thus the boiler’s efficiency and raises operating costs. However, excessive sootblowing can erode the boiler surface, creating thermal stress and requiring extra use of auxiliary power and sootblowing medium. Ideally, condition-based sootblowing should balance heat transfer and the effects of fouling against other parameters, including cleaning intervals and the long-term effects of ash removal, for an optimal schedule that minimizes the impact on hardware and operations.
In addition to these necessary cleaning processes, which must be done efficiently, the sootblowing optimizer is the perfect tool to complement the optimizer on the combustion side. While the combustion optimizer handles the fuel-air coordination and related heat generation, its complement, the sootblowing optimizer, ensures that the subsequent transfer of heat to the water-steam cycle is shaped and controlled strategically so as to complete the task of boosting efficiency.
The twin efforts to optimize combustion and sootblowing were coordinated to make the best possible use of fuel, lowering costs and further boosting profits. The optimization increased Alcudia’s net relative efficiency by 0.83 percent averaged over the entire load range, significantly more than the project target of 0.5 percent. Such performance optimization can make all kinds of steam turbines, boilers, or control systems more profitable – whether they be Siemens-made or designed by another company.
In all cases, the Omnivise Plant Optimizer package ensures that operations are adjusted for optimal output based on local conditions and the specific characteristics of the power plant, to improve availability, flexibility, and efficiency while lowering emissions. By setting the correct parameters, asset owners can ensure that their repowered asset will return the best possible results in its remaining lifespan.
Endesa is the leading electricity utility in Spain and the second-largest operator in Portugal. With a distribution grid of 319,600 kilometers and total generation of 74.2 GW (2016), it supplies power to more than 21 million customers on the Iberian peninsula and its island territories.
Carl Fischer is an independent journalist specializing in business and technology news. He lives and works in Zurich, Switzerland.
Combined picture and video credits: Siemens
You should ask yourself these 10 questions:
If your answer to any of these questions is “yes”, a digital performance optimization for your power plant could be intereseting for you.
- Do you have to improve the efficiency?
- Do you have to reduce emissions? (NOx, CO, CO2)?
- Is the unit operated under varying loads?
- Is the maximum output limited by the furnace?
- Is the plant operated at low output for long periods of time?
- Do you burn different types of coal?
- Would you like to burn more auxiliary fuels?
- Does the ash have a high loss of ignition?
- Do you have problems with slagging?
- Do you have fireside corrosion, i.e., cracked pipes?
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