Questions regarding ammonia injection for denitrification of coke oven flue gas
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For denitration of coke oven flue gas, 20% ammonia water is generally used as a reducing agent. Can ammonia water be sprayed directly into the flue ducts of coke oven exhaust gases – such as the main exhaust duct or the steel ducts on the ground leading from the main duct – without being diluted first? Is there a risk of explosion or any danger? The temperature of the flue gas from coke ovens can reach up to around 350 degrees. Thank you all
This post was last edited by su200595su on 2016-9-19 10:15 :)
It must be very difficult to meet environmental standards! Furthermore, a certain amount of ammonia will definitely escape! The next goal in environmental protection efforts is to address ammonia emissions after desulfurization and denitration!
Some people did this; they also sprayed excess ammonia water into the chimneys for treatment, and no explosions occurred
The remaining ammonia water comes into countercurrent contact with the flue gas; some of the sulfur dioxide should be absorbed by the ammonia water, and some of the ammonia water will evaporate as well. It is merely a process of heat exchange and cooling, with no conditions for an explosion to occur.
No, this approach requires a large amount of ammonia; in other words, it is a speculative method. It involves reducing sulfur dioxide in the flue gas without taking into account the issue of ammonia. Currently, for desulfurization and denitrification, excess ammonia water is used, as coking itself generates a certain amount of ammonia water!
It shouldn’t work; the flue gas temperature is too low. Using ammonia means it’s no longer within the reaction temperature range for SNCR denitration. The typical temperature range is 900–1200 degrees, and applying ammonia at a flue gas temperature of 350 degrees will only lead to increased ammonia escape； However, if there is an SCR catalyst installed later on, it can also play a certain role; but this type of process is not recommended as it is not cost-effective!
Our company sprays ammonia water into the main flue; it is ammonia water from after the ceramic membrane filter, and sulfur dioxide levels can be reduced to 0. However, nitrogen oxides do not react at this temperature, so it has no effect on them.
Many factories have done this; if the spraying is even, it is possible to reduce both sulfur dioxide and nitrogen oxides to acceptable levels. Wet ammonia desulfurization also has a certain nitrogen removal effect, primarily by absorbing NO2. The reaction principles are as follows: 2NO2+H2O=HNO3+HNO2; NH3+HNO3=HN4NO3+H2O; NH3+HNO2=NH4NO2+H2O; 4(HN4)2SO3+2NO2=N2+4(NH4)2SO4