In fossil fuel power generation the environmental protection takes on a greater significance. Besides the introduced processes of reducing dust, NOx and SO2 emissions, greenhouse gases and pollutants (e.g. HCl, VOC, …) are gaining more importance in alternative fuelling.
SICK analyzing systems provide continuous monitoring of power plant processes. Using SICK measuring techniques, concentrations of the gas components and dust as well as the volume flow can be monitored at various points in the plant. Thereby, variations in the process can be easily identified and optimized.
Pulverized coal is typically used to fire the boiler of power plants. Due to safety reasons, monitoring of CO in coal bunkers and coal mills is an essential issue. CO is an odorless and very toxic gas and imposes a serious explosion thread at levels above 8 vol.% in air. Enhanced CO concentrations may indicate a seat of smouldering and require immediate counter measures. In addition, O2 concentrations provide significant information for coal grinding plants which are operated under inert purging conditions: An increasing oxygen concentration value monitors the entrance of false air into the system and thus protects against the risk of explosion. Our solution:
Power plant efficiency requires continuous monitoring and optimizing of the combustion process. Supply of combustion air is a primary task in this respect because it delivers the required amount of oxygen, which must be optimized and controlled carefully to ensure safe and efficient combustion, to minimize fuel consumption as well as emission of pollutants like CO, CO2, NOx. Therefore, reliable and accurate monitoring of primary combustion air volume flow at the boiler inlet is a very important task. Our solution:
Environmental regulations demand efficient reduction of the NOx content of the flue gas before it is released into the atmosphere. The Selective Catalytic Reduction (SCR) process is typically applied for that using an added reagent such as ammonia (NH3) which converts nitrogen oxide into water and nitrogen over a catalyst at approx. 400 °C. NO concentration is measured at the inlet of the DeNOx plant to determine and control the required amount of ammonia. At the outlet of the DeNOx plant NO and NH3 are measured: The NH3 concentration (ammonia slip) indicates the efficiency of the denitrification process while the NO concentration is controlled to ensure compliance with the environmental regulations. Our solution::
Flue gases from coal fired combustion processes are loaded with particulate matter (PM) and, due to environmental regulations, must be cleaned before release into the atmosphere by passing a dedusting device. Bag-house filters are mostly used where the particles are collected by passing through a tightly woven fabric. Alternatively, electrostatic precipitators are in use where the particles are collected on electrodes by passing through an electric field. The correct operation of the dedusting plant and compliance of the residual dust content with the regulations is ensured by continuously monitoring the dust concentration after the filter. Our solution:
Wet scrubbing systems are typically used for flue gas desulfurization. After leaving the dust removal plant, the flue gas enters a tower where it is sprayed with a calcium-based slurry (scrubbing liquid, e.g. ground limestone in water) that is fed from a tank. The gaseous pollutants such as SO2 are solved in the liquid and react with the liquid to form calcium sulfite or sulfate which are removed by dewatering and settling into a thickener. Alternatively calcium sulfite is oxidized to form gypsum by bubbling compressed air through the sulfite slurry. Our solution:
Depending on the kind of fuel and local environmental regulations, a number of gas components, preferably CO, NOx and SO2 are to be monitored continuously in the flue gas at the stack along with dust (particulate matter, PM), gas flow, temperature and O2 (sometimes H2O as well). In case of co‑incineration of alternative fuels, additional components such as HF, HCl, Hg and VOC may be required to be monitored as well (emission monitoring in waste incineration). Measuring data are transferred to a specific data acquisition system for further processing and reporting to the authorities. Measuring equipment used for CEM applications must be approved by the government after having successfully passed a type approval test. Our solution: