I would like to ask the experts about NOx removal processes
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I would like to ask everyone about an integrated desulfurization and denitration technology that uses sodium hydroxide or sodium carbonate solutions for desulfurization; the sodium sulfite generated as a result of this process is then used to reduce the oxidized nitrogen oxides back to nitrogen gas. The absorbent after denitration is converted back into sodium hydroxide using calcium hydroxide, allowing the absorption solution to be reused. This is a technology that differs significantly from other double-alkali methods. The principle of its desulfurization and denitrification technologies is as follows: 2NaOH + SO2 = Na2SO3 + H2O; 2NO2 + 4Na2SO3 = 4Na2SO4 + N2; 2NO + O2 = 2NO2. These technologies are suitable for situations where the concentration of sulfur dioxide in industrial flue gases is 3–4 times higher than that of nitrogen oxides. Is this reaction valid? Does such a denitration technology exist?
It is difficult to ensure the gas-phase partial pressure of nitrogen dioxide; the theory you mentioned holds true.
Theoretically feasible, suitable for processes that remove very small amounts of nitrogen oxides; personally, I think the cost is too high.
The reaction is feasible, but it should be noted that the rate at which NO is converted to NO2 is relatively slow. Additionally, during the initial absorption phase, the concentration of sodium sulfite or sodium bisulfite in the tower is low, resulting in severe NOx leakage； Additionally, in systems with internal circulation, the two salt solutions tend to crystallize in winter; without such circulation, the amount of waste water generated is excessive. This approach seems suitable for temporary treatment in situations where the volume of gas handled is low and production is intermittent
Thank you for your answer. I think it’s very difficult to remove NOx in actual engineering applications
Thank you for your participation. In my opinion, it’s not a matter of having written rules, but rather whether it’s possible to remove NOx in actual engineering applications
It’s actually possible; I’ve used it before. But when the concentration is high, it’s necessary to increase the concentration of the absorbing solution significantly, which makes crystallization more likely and makes the operation inconvenient
The results may not be that good; it seems like the cost is very high
I think it’s theoretically feasible, but it’s not easy to achieve under the conditions of actual industrial operation
This reaction is possible, but it is difficult to achieve in practice. Firstly, the majority of NOx in flue gas exists in the form of NO, and NO is hard to oxidize into NO2. Secondly, with the limited reducing power of Na2SO3, it is not possible to reduce NO2. With these three points, this denitration technology can be dismissed outright; the logic is extremely simple: first oxidize NO to NO2, and then reduce NO2 to N2. Oxidize first and then reduce? ? ? Then why don’t you simply reduce NO? ? It doesn’t make logical sense. . What makes logical sense is necessarily something that can be applied on a large scale in engineering; for example, SCR involves the direct reduction of NO by NH3. . .