Ammonia escape - Analysis of ammonia desulfurization pain points
The basic principle of ammonia desulfurization process
Ammonia desulfurization is the whole process of mutual mass transfer heat conduction and chemical change in the middle of gas-liquid two phases.
In this desulfurization reflection, (NH4)2SO3 plays a key role in the absorption of SO2, and along with the implementation of the reflection, the concentration of (NH4)2SO3 will slowly decrease and the concentration of NH4HSO3 will slowly increase. In order to better maintain the absorption level of the FGD circulation system liquid, ammonia needs to be introduced into the slurry pool to convert NH4HSO3 into (NH4)2SO3, and to better prevent the converted (NH4)2SO3 from being converted into SO2 again, (NH4)2SO3 is compulsorily oxidized into (NH4)2SO4 by the oxidation gas drummed into the oxidation centrifuge.
Ammonia fugitive causes
Ammonia escape refers specifically to the condition of vapor ammonia discharged from the desulfurization equipment with the soot. In ammonia desulfurization projects, the key factor that generally leads to ammonia escape is the high composition of dispersed ammonia in the liquid of the desulfurization cycle system. Ammonia is an extremely volatile chemical, and ammonia is a gas at room temperature and pressure. Therefore, ammonia concentration and temperature need to be reduced to the lowest possible level in an ammonia desulfurization project. The amount of ammonia required for desulfurization is determined by the amount of sulfur dioxide removed from the soot, so the only way to better reduce the concentration of ammonia in the absorption solution is to increase the amount of the absorption solution circulation system and, in addition, to reduce the temperature of the absorption solution.
In addition, the low oxidation rate of ammonium sulfite is another factor that leads to a more serious ammonia escape. The ammonium sulfite converted to desulfurization is not a smooth chemical, and if it is not immediately oxidized to smooth ammonium sulfate, it is very easy to be converted to sulfur dioxide and ammonia, resulting in a rise in sulfur dioxide in the effluent soot and an increase in ammonia escape.
All hearts and minds find countermeasures
Along with the gradual improvement of the ammonia desulfurization process and the widespread use of ammonia fugitive situation has also transformed into a difficult point of rectification, and there are even areas promulgated in the gas treatment plan program clearly specified - in the choice of ammonia desulfurization process, ammonia fugitive rate concentration must be less than 8mg / cube. Do ammonia desulfurization of environmental protection equipment companies have a lot, but the technical strength of the mixed. And then after many companies continue to try continuous testing to find the key factors that jeopardize the high efficiency of SO2 absorption and ammonia escape.
(1) Strictly control the oxidation of ammonium sulfite in the oxidation section to achieve a high oxidation efficiency of 99.8% or more;
(2) Strictly control the pH of the absorption solution after adding ammonia (5~5.5) to ensure that the SO2 absorption rate is more than 99.5%;
(3) looking for good ammonia addition part, the product developed the ammonia chamber in front of the pump, effectively manipulate the amount of ammonia addition, and then manipulate the ammonia amount in the absorption section is very low, to ensure that the discharge net soot ammonia fugitive amount is under 1.0Mg/Nm3, the actual measured value is 0.43mg/Nm3.
Solve the ammonia escape, not only improve the high efficiency of desulfurization, but also save the operation cost fee, ammonia desulfurization processing process in the future industrial production of gas treatment will certainly be more widely used to help promote industrial production to complete the ecological and environmental protection cycle system approach.
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