46 ARTICLE / MAKALE O To further reduce fuel cost different imported coals are utilized and waste fuel from different sources is introduced. O The operation mode of plants has been changed e.g. from base load to mid range load or vice versa. O Future operation concepts for existing power plants alsa have to make sure that the required power for frequency support because of increased regenerative generation is available. O Environmental legislation has been mainly focusing on dust emission in the early years, today SO2 and NOx emissions are concerned as well, in future there are lower emission limits to be expected and also the CO2 emissions have to be considered. Due to the changes of the basic conditions the original plant design is mostly not the optimum design for today's requirements. Optimization of existing plants means from our point of view, to analyze the actual plant design (which might be different from the original design due to adaptations already carried aut) with a structured assessment and to develop improvement measures, which are economically viable and can be implemented during an overhaul of the respective unit. Conception Figııre I: Coııceptioıı of plaııt optimizatioıı To fulfill this comprehensive optimization task in short time and at moderate costs, ALSTOM Power Service has developed a specific process (Figure 1) called ECOI RAM, which provides the assessment structure, benchmarks for technical and commercial parameters and basic technical concepts for the improvement of power plants. lnstead of a detailed explanation of the process including tools and data applied, which would go beyond the scope of this paper, we will exemplarily explain the basics of technical benchmarking which is used in the ECOIRAM process. Benchmarking means to compare technical or commercial parameters with reference values. The difficulty of benchmarking is: O To make sure that an adequate reference value is used. (Comparing apples with apples and not apples with pears) O To derive a feasible, economical and sustainable solution based on the benchmarking results. ENERJİ & KOJENERASYON OONYASI To make sure that the right reference values are used we are comparing data which have been adjusted to reflect specific conditions as e.g. fuel, component design and material and operation mode (Figure 2). This means that if we are for example comparing the flue gas temperature after the air pre heater, which is an important parameter for the boiler efficiency, we have to consider e.g. O The flue gas temperature upstream the air pre-heater O The fuel composition as e.g. the sulfur content and the ash composition impacting fouling behavior of the air preheater and SO3-dewpoint. O The design of the air pre-heater: e.g. heat transfer surface type and area O The material of the heat transfer surfaces e.g. enameled elements on the cold side O Load of the unit and ambient temperature Technical Benchmarking , � ... Fueı ,., Q · ... Design �� • . ... Materıaı • ... Operaıion Technicat benchmarking requires the consideration of boundary conditions as e . g. fuel, design, material,... Example-air preheater • ""� ·Fueı SulfUf-conlent • w Flue gas ... Fuel •AshCompos.t ı on � y_d,;_ tcmpe�ature r-\ ... Design •Ai r pıch<ı.-ıter rypo _ 1;-;f.;/ after aır L...../ ·Heaı ır.ıınsfer surface � ,....... •··-· ·--% ... Operation •/JıJ r ıemperaıu,e ,,ım_JjAZ •LoadMN Figııre 2: Techııical Beııchnıarkiııg To derive solutions based on the benchmarking process a comprehensive catalogue of improvement measures based on benchmarking findings has been developed. in this way the benchmarking is linked to the development of solutions. 3. Examples in the following it is highlighted on the basis of two examples how improvement potentials are identified, how based on these findings improvement measures are elaborated and which benefits are created by the implementation of the improvement measures. The first example concerns the reduction of maintenance costs. Figure 3 shows the maintenance costs (line graph) and the unavailability (bar graph) caused by the respective system. it is clearly visible that certain components as e.g. the boiler are a major contributor to loss of production and alsa a major amount of the maintenance budget is spent for the component. in case of the fuel handling system there is no loss of production caused by the fuel handling system but there are significant maintenance costs spent for the fuel handling system. Task of the further investigation was to develop a maintenance strategy for the fuel handling system with lower cost and without causing loss of production.
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