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Double subtraction desulfurization technology
2017-03-16 13:43:15 184 views

Double alkali method (Na2CO3Ca(OH)2) in lime method based on the combination of sodium alkali, the salt soluble in water, in the absorption tower with sodium alkali absorption SO2, desulfurization liquid absorption after regeneration tank using cheap lime for regeneration, which makes use of sodium ion absorption cycle.The process combines the characteristics of lime method and sodium alkali method, solves the problem of easy scaling in the tower of lime method, and has the advantages of high sodium alkali absorption efficiency.

Double alkali method is widely used in medium and small boilers for flue gas desulfurization technology, which is developed to overcome the shortcomings of limestone lime method. There are many kinds of double alkali method, the most commonly used is sodium calcium double alkali method.

Sodium calcium dual alkali (Na2CO3--Ca(OH)2) using soda absorption SO2, lime regeneration, regeneration after absorbent recycling, no waste water discharge.


Chemical reaction principle

The absorption of SO2 in the tower

Na2CO3SO2Na2SO3CO2 1

2NaOHSO2Na2SO3+H2O  2

Na2SO3SO2H2O2NaHSO3  3


Sodium alkali regeneration

CaOH2 Na2SO32NaOHCaSO3

CaOH2 2NaHSO3Na2SO3CaSO3H2O1 H2O


In the lime slurry (of lime to saturated condition), NaHSO3 and CaOH2 quickly response to release (Na +), [SO32 -] and [Ca2 +] reaction, reaction generated CaSO3 settle with hemihydrate form so that [Na +] get rebirth. Na2CO3 is just a start, actually consumed after starting is lime, theoretically no consumption of soda ash (just slag removal will take some, too, so a small loss) 


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