No.064 ; Magnesium Hydroxide Method Wet Type Flue Gas Desulfurization

No. 064

Classification of Technology:: Air Pollution Control
Type of Industry:: Others
Subject:: Magnesium Hydroxide Method Wet Type Flue Gas Desulfurization
Equipment ( Coal burning boiler )

1. Purpose
Reduction of SOx in boiler exhaust gas.

2. Details and the Time
The compact and low pressure loss magnesium hydroxide method with high desulfurization and dust removal performance was introduced as the flue gas desulfurization measures when installing the coal burning thermal power station.
( Operating from April, 1990 )
3. Principle
(1) Mechanism of desulfurization reaction
1) Exhaust gas containing SO₂ comes into contact with the absorption fluid in the scrubber and, in addition to being humidified and cooled until saturated, SO₂ and dust are removed.
2) On the reaction in the scrubber, air is blown into the bottom part of the scrubber, where magnesium sulfite of low solubility is oxidized to the magnesium sulfate of high solubility, preventing the scaling trouble.
3) Reaction : SO₂ + Mg(OH)₂ -> MgSO₃ -> MgSO₄
4) Waste water from the Desulfurization process is discharged after treated and sludge separated.
(2) Management point
1) pH of fluid absorbed ; 5.5 - 6.0
2) MgSO₃ ; Over 10 mllimol/l
(3) Dust removal performance
1) Counter flow contact spray type with extremely low pressure loss of 30~50 mmAq.
2) Suitable for removing dust with grain diameter of 20~30 microns.
See next page for flowsheet.

4. Effect and Achievement
(1) Denigration : ( Inlet ) 240 - 260 ppm -> ( Outlet ) 20 ppm or
under
(2) Dust removal : ( Inlet ) 30 - 40 mg/Nm3 -> ( Outlet ) 10 mg/Nm3 or under

Implementing company:: Nippon Steel Corporation yard, Tokai Co-operative Power Company Inc.

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