Waste management today is increasingly supported by incineration processes. Here the organic compounds of waste are used to produce energy in waste incineration plants or as alternative fuel in cement kilns or even coal fired power plants. For the emission of these plants special regulations are applicable where as the emission limits are more stringent than for conventional power plants.
SICK analyzing systems are highly qualified for waste incineration applications. With its wide range of products SICK is able to provide the optimal solution for all relevant parameters, even for the most stringent European Waste Incineration Directive. SICK is the only manufacturer with own solutions for dust, gas flow, pollutants, reference gases, and data evaluation systems.
Combustion processes require O2 to react chemically with the fuel. Incineration of waste materials converts the waste into ash, flue gas, particulate, and heat, the latter can be used to generate electric power (waste to energy). O2 is supplied to the combustion process via combustion air. Monitoring the O2 concentration at the boiler outlet is the most important measure for control and optimization of the incineration process. Our solution:
Due to environmental protection NOx emissions have to be reduced prior to the release into the atmosphere. In the NOx control process with selective non-catalytic reduction (SNCR) either gaseous ammonia or a mixture of urea and water is sprayed directly into the combustion chamber at temperatures between 900 °C and 1.100 °C. Here NOx molecules react with the ammonia compounds and form nitrogen and water. The NOx emissions are reduced accordingly. In addition to O2 (boiler efficiency), NO is monitored at the boiler outlet for control and optimization of the DeNOx process. With the same system HCl, SO2 and H2O concentrations can be monitored as important control parameters for a subsequent scrubber. Our solution:
For the process with selective catalytic reduction (SCR ) gaseous ammonia is fed into the catalyst inlet. The conversion of NOx into water and nitrogen takes place at temperatures between 200 °C and 400 °C. At the inlet of the catalyst NO concentration is monitored to control the ammonia injection. At the outlet of the catalyst NO and NH3 are measured: The NH3 concentration (ammonia slip) indicates the efficiency of the denitrification process while the NO concentration is monitored to ensure compliance with the environmental regulations. Our solution:
After the dedusting typically scrubbers are used to remove acidic gases like HCl and SO2. Two scrubbing processes are used, wet scrubbers and (quasi-)dry scrubbers. In wet scrubbers the flue gas is sprayed with an aqueous mixture of water and lime. The gaseous acidic pollutants react with the liquid to form gypsum which can be removed from the waste water to produce drywalls. Using the dry scrubbing process the aqueous solution is replaced by lime powder or a pasty mixture of water and lime. For proper operation control of the dry process continuous monitoring of HCl, SO2 and H2O concentrations is essential. Our solution:
For controlling the emissions of heavy metals and dioxines / furanes activated charcoal filters are a commonly used method. Activated charcoal has a high porosity combined with a large active surface and is therefore ideal for adsorption of pollutants. Disadvantage of use of activated charcoal is the self combustibility. Early detection of hot spots in the charcoal filter is possible by using differential CO measurement between in- and outlet of the filter. Our solution:
According to environmental regulations, waste incineration plants have to monitor continuously a large number of gaseous components (HCl, HF, CO, NOx (NO+NO2), SO2 and VOC), particulate matter, as well as the reference values gas flow, gas temperature, pressure, O2 and H2O. In some countries additional continuous monitoring of total mercury is obligatory (e.g. Germany). The monitored data is transferred to an emission data acquisition system for further processing and reporting to the authorities. Monitoring equipment used for CEM applications must be approved by the government (for example Waste Incineration Directive 2000/76/EC). Precondition is an approval test according to EN15267-3, and fulfilling the quality standard EN14181. Our solutions: