Upgrading power plant furnaces for the demands of tomorrow
Flexibility in the operation of fossil fuel power plants is increasingly becoming a success factor. Responsible for this are three factors: coal is available on the world market in greatly varying qualities. The inconsistent power of alternative energy must be compensated by the conventional power plants through load flexibility in order to guarantee the security of supply of the extremely important electrical power. With all its flexibility power plants must always operate economically and comply with emission levels.
Better control for more flexibility
Flexibility needs control. As a fossil fuel power plant must respond quickly to load demands today, combustion control becomes more and more dynamic. It is no longer sufficient to find once the optimal mode of operation. It must be achieved again and again under the changing demands and conditions. Fast and precise information about the temperature in the combustion chamber temperature and its distribution is thus indispensable.
Local temperature: central indicator for the local stoichiometry
In order to control the coal combustion process in this complex scenario, average temperatures are not sufficient. Temperature imbalances must be detected and reduced to ensure that the combustion remains in the optimal balance of efficiency and emission even with changing fuel qualities and load requirements. With the active balancing control the best possible conditions in terms of efficiency, NOx, CO, burnout and corrosion can be achieved by optimizing the local stoichiometry over the entire combustion chamber.
Temperature imbalances of more than 200 °C without active balancing control
Without this specific control temperature imbalances of 200 °C and more in coal-fired boilers are normal. With the active balancing control, they can be eliminated by small controlling interventions. Thus, for example, a change of the local stoichiometry of 5 % causes a local change of the temperature at the end of the combustion chamber end of approximately 100 °C.
0.5 % more efficiency and less unburned residues due to reduced temperature imbalances
Since non-uniform temperature distributions in the combustion chamber always lead to an uneven combustion, sufficient secondary air must be added so that carbon monoxide is oxidized in all temperature zones. The active balancing control supported by agam reduces these temperature imbalances significantly. The result: less secondary air and higher efficiency.
A more uniform fireball has a positive effect on the steam situation as it results in reduced imbalances between the superheater sections and a lower volume of injection water. They also improve the proportion of unburned residues in the ashes.
The EDF power plant Rybnik increased its efficiency with the combination of agam and an optimizer of Emerson by 0.5%. This corresponds to savings of 3,000 tons of coal and 8,000 tons of CO2 per year.
Reduced temperature imbalances, less corrosion
The air ratio to be chosen for the combustion is in the conflict area between efficiency, NOx emission and corrosion prevention. If the air ratio decreases the corrosion risk increases. Resulting wear always occurs locally and can neither be detected nor avoided with average values. The active balancing control with agam keeps the local temperatures throughout the combustion chamber in a range which avoids unnecessary and expensive corrosion and clogging of the system.
More uniform temperatures produce less nitric oxide
Just as the air ratio may decrease locally too much, it may also increase locally too much. In the worst case NOx occurs at one end of the boiler, while corrosion is caused at another place by lack of air – despite the correct average temperature. The uniform temperature distribution which can be achieved with agam thus favors a low-NOx operation of the burners. This lowers the effort for the subsequent catalytic or non-catalytic denitrification process.
SNCR in fossil fuel power plants
Since the 90s, SNCR systems with agam are state-of-the-art in waste incineration plants. With the local temperature data, agam provides the basis for a precise and exact injection of the additives. In conjunction with modern high-performance SNCR systems, waste incinerators are able to reach NOx values below 100 mg/m3 continuously.
Since 2010, this modern denitrification technology is more and more installed in power plants. In 2015, more than 50 coal boilers with capacities of 200-500 megawatts are already equipped with agam for non-catalytic denitrification.
Optimization of fossil fuel power plants since 1980
Since 1980, Bonnenberg & Drescher is working to optimize fossil fuel power plants. Since 1991, our agam system measures the gas temperature and its distribution in power plant furnaces – free from radiation effects, drift and clogging. Since then we have continuously refined our know-how in more than 70 fossil fuel power plants.
The best solution for your power plant furnace
With more than 30 years experience in the power plant industry, we know that every furnace is individual. That's why we do not offer products “off the shelf”, but we are always looking for the best solution for each facility.
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Examples in fossil fuel power plants
agam reference plants
The following power plants use agam successfully:
- La Spezia
- Le Havre
- Meja, UP
- North Yorkshire
- Schwarze Pumpe