| Power plant upgrade


management team at Eren Enerji called in RJM to assess the plant and propose a solution that would address all the key issues.


Poor combustion identified RJM spent a considerable amount of time analysing the problems at ZETES 2 unit 3 and the combustion audit (site survey), combined with associated CFD analysis, confirmed that the dynamics of the Dongfang burners were actually very poor.


Each burner was set up individually, with different swirler settings, resulting in 24 different sets of competing burner dynamics. This resulted in long flames and uncontrolled combustion and high levels of excess air.


The incomplete combustion was such that the over-fire air system was unable to complete combustion of the unburned fuel as it could not penetrate to the centre of the combustion chamber.


In addition, the burners were being thermally damaged, due to the presence of flames within the burners themselves.


Poor combustion was also responsible for the high levels of CO.


Taken together, these findings confirmed that the entire burner and combustion system needed to be modified. There then followed a sequence of CFD studies to help identify the optimal solution.


Developing a solution


RJM focused on its well-proven staged approach, with detailed engineering tailored to the precise requirements of the plant and a common-sense philosophy that provided new RJM burner components but retained as many “non- performance critical” components as possible. By adopting this pragmatic approach, the old equipment removal / new component installation phase of the project was completed very quickly – within a ten week outage.


At the heart of RJM’s solution were 24 bespoke sets of ultra-low-NOx


burner modifications,


tailored to the precise requirements of the Dongfang boiler and with interfaces engineered to fit.


Installation of the new RJM equipment, along with ancillary components, took place during the planned outage of spring/summer 2024.


Performance improvements As well as delivering the performance objectives in terms of addressing combustion instability, poor efficiency, burner damage, high CO and control of NOx


prior to the SCR,


the performance results, summarised below, confirm that, in addition, the plant is now able to generate the same amount of power using less fuel and less reagent, with one fewer mill in service.


Less fuel translates to lower CO2 emissions


– an important objective for Eren Enerji – and the upgrade has reduced emissions of CO2


over 80 000 tonnes per annum on a like-for- like basis.


In addition, the RJM upgrade, by reducing flue gas flow, delivers significant operational cost


by


savings in terms of fuel, reagent for the SCR and fan power consumption. It also achieves further cost savings by extending the life of the SCR catalyst and avoiding future costs associated with tube leaks.


After the commissioning phase, overall performance of the plant post upgrade fulfilled the contractual performance guarantees and met and exceeded all Eren Enerji’s objectives and expectations.


Key performance improvement data for the ZETES 2 unit 3 project is summarised in the table below.


Parameter Improvement NOx


(mg/Nm


CO (mg/Nm3 Carbon in ash Boiler efficiency Mills in service


) 47% less ) 49% less 50% less 2% more One less


Mill motors and fans Mill mechanical power


14% less power consumed


9% less power consumed


emissions reduction 80 000t per annum The RJM approach


Reagent for SCR (kg/day) 70% less required CO2


As power generators all over the world are embarking on their own transition programmes to net zero, identifying where efficiency savings can be made and reductions in emissions achieved – cost-effectively – and without threatening the reliability and integrity of the plant, is of the utmost importance. By focusing on engineering assessment, coupled with advanced equipment design, RJM aims to deliver the optimum combustion and emissions control solution.


While the technology is applicable to all boilers, its attention to engineering detail is particularly important for older boilers, where the retrofit of new technology can easily exacerbate existing operational problems or create new ones.


RJM’s philosophy is therefore that combustion solutions must be customised for each site to ensure project objectives are met without compromising current operations.


The key elements of RJM’s strategy are the combustion audit (site survey) and baseline testing which help identify pre-existing operational problems. A detailed engineering assessment of these pre-existing plant issues is then undertaken and state-of-the-art CFD modelling is applied to assess the impact of the proposed upgrade on operational parameters, to deliver the optimum solution.


The project road map adopted for ZETES 2 unit 3 (and for other similar projects) was as follows:


Preliminary project work combustion audit;


airflow distribution – CFD isothermal; baseline test;


CFD single burner model (existing burner); CFD full furnace model.


Main project work physical modelling; detailed burner design; burner manufacture; HAZOP study; commissioning;


optimisation & performance tests; guarantees.


Ultra low NOx The RJM ultra low NOx


burner burner is manufactured


to the highest standards and out-performs OEM equipment. It features: high alloy castings;


state-of-the-art components; ease of installation; long life;


excellent performance; full spares back-up.


In the ZETES 2 unit 3 case, having configured the new ultra low NOx


burners to fit the existing plant


interfaces, installation was problem-free. This was followed by the commissioning phase, which focused on fine-tuning the burner airflow balance. The unit was then returned to service with oil burner commissioning optimised as a first stage, followed by PF coal firing with solid and stable flames confirmed. Commissioning was successfully completed within two weeks of the end of the outage.


www.modernpowersystems.com | March 2025 | 15


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