No. 059


Classification of Technology:

Air Pollution Control

Type of Industry:

Chemical

Subject:

Processing of SOx, NOx and Dust Discharged
from Coal Burning Boilers



1. Purpose
To reduce discharge of SOx, NOx and dust in line with the installation of the private coal burning power generating plant.

2. Details and the Time of Introduction
Flue gas desulfurization facilities, exhaust gas denitrizer and exhaust gas dust collector ( bag filter ) were installed as the environment protection equipment to realize harmony with the local environment.
After implementing this plan, the amount of discharge of sulfur oxides, nitrogen oxides and dust actually decreased despite an increase of about 40% of steam generation. ( June, 1994 )

3. Principle
(1) Flue gas desulfurization facilities
SO2 + Mg(OH)2 -> MgSO4 + 1/2 O2 -> MgSO4
High desulfurization is realized compared with the lime gypsum method.
The extended period continuous operation is possible without problem of the scale trouble.
(2) Exhaust gas denitrizer
4NO + 4NH3 + O2 -> 4N2 + 6H2O
2NO2 + 4NH3 + O2 -> 3N2 + 6H2O
The dry type ammonia catalytic reduction method with high achievement was adopted because of its high level of reliability and safety in exhaust gas denigration.
(3) Exhaust gas dust collector
The bag filter system was used since in the case of coal burning boilers, the electric resistance of fly ash in the exhaust gas is high and will cause the reverse electric dissociation to occur in the electric dust collector and will lower dust collecting performance.
See next page for overall flow scheme.

4. Effect and Achievement
(1) Rate of removal
Sulfur dioxides = 90%
Nitrogen oxides = 70%
Dust = 99%
(2) Comparison of the Emisson Amount per 1ton/H steam before/after the Application of the plan.
ItemSteam generation Capacity ( t/H )Emission Amont per 1t/H Steam
SOx ( NM3 )
NOx ( Kg )
Dust ( Kg )
Before
After
107.5
153
0.137
0.079
0.258
0.154
0.072
0.030
Rate
42% Increase
42% Decrease
40% Decrease
58% Decrease

5. What to do next ?
To improve the SOx removal rate.




Implementing company:

Mitsubishi Gas Chemical Co., Ltd. Yokkaichi Plant


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