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![]() Treatments using fuel additives or injection processes can drastically effect the flue gas composition.
Applications
- SO3 Injection to improve Precipitator performance
- Monitoring Fuel Additives
- Quantify and Reduce Toxic Release Inventories (TRI)
SO3 Injection to improve Precipitator Performance
The injection of SO3 into flue gas immediately prior to the precipitator changes the resistivity of existing particles and enhances the performance of the Electrostatic Precipitator (ESP).
When the ash is over-saturated, the process gas has higher levels of free SO3, which will create a higher acid dewpoint temperature and hence a higher probability of cold end corrosion and acid emission. If there is too little SO3, the ESP performance will suffer leading to increased particulate emissions to the atmosphere.
Monitoring Fuel Additives
Many processes require the injection of MgO, inorganic metallics or activated Magnesium, for the minimization of SO3 formation and reduction in the corrosion and pollution effects of burning high sulfur fuels.
Too little of these additives will lead to higher levels of SO2 forming free SO3, which in turn will increase the acid dewpoint temperature. This can result in increased emission of pollutants into the atmosphere, and lower thermal efficiency.
If the process is over saturated with additives, this may cause excessive dust or ash, creating dirty boilers, which will limit boiler performance, create hot side inefficiencies and in some cases inhibit the combustion gas flow through the process, consequently lowering the performance.
Quantify and Reduce Toxic Release Inventories (TRI)
sulfuric acid aerosol emissions created by 'free SO3' are considered a toxic release. It is necessary to quantify these emissions as part of a Toxic Release Inventory (TRI).
Free SO3
Free SO3 in flue gas streams from coal and oil-fired boiler systems can be defined as the level of SO3 in the vapour state, which does not include SO3 already deposited onto the fly ash. This is the most significant parameter in the acid aerosol emissions.
At temperatures below 175 ºC / 350 ºF, 99.7 % of the free SO3 becomes H2SO4 in the presence of H2O concentrations greater than 8 %.
Sulfuric acid mist is formed at flue gas temperatures below the acid dewpoint temperature.
Monitoring Solutions
The most direct method available to quantify these emissions is to measure the acid dewpoint temperature (ADT) from which direct concentrations of sulfuric acid (H2SO4) can be calculated.
Acid dewpoint temperature monitoring is the key parameter for operators to balance acid emissions with efficiency; and indicate the onset of reportable TRI emissions.
LANCOM 200 - portable analyzer
It is designed specifically for plant requiring only periodic monitoring of the sulfuric acid dewpoint temperature for boiler efficiency checks, corrosion protection and evaluation of the effectiveness of corrective measures such as fuel additives and changes in the combustion conditions.
For more details go to 'LANCOM 200 - Sulfuric Acid Dewpoint Temperature Monitor'.
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