Page 188 - New Trends In Coal Conversion

Technologies for control of sulfur and nitrogen compounds and particulates 151

Wellman-lord process
Wet processes
DESONOX process
Regeneration
processes
Dry processes Activated carbon process

Flue-gas
desulfuration
processes
Dry processes Sorbent injection

Non-regenerative Semi-dry
Spray-dryer absorption
processes processes
Lime (stone) scrubbing
Sodium (hydroxide)
scrubbing
Ammonia scrubbing
Wet Hydrogen peroxide
processes scrubbing
Seawater

Dual alkali
Others
Figure 6.4 Summary of the SO x abatement techniques available at industrial scale (European
Commission, 2006).

Wet scrubbers lead the market, covering 81.7% of the total installed DeSO x units in
coal-fired power plants. Other techniques such as spray driers and sorbent injections
contribute to only 13.8% of the total DeSO x capacity systems installed (Poullikkas,
2015).

6.2.2.3.1 Precombustion control techniques
Precombustion control techniques are considered primary measures because they aim
at preventing SO 2 formation and hence the effects associated with their emissions.
These techniques are based on either switching to a low sulfur-containing fuel or
reducing the bound sulfur in the fuel. SO 2 emissions are directly related to the amount
of sulfur contained in the fuel. The use of a cleaner fuel leads to a further reduction in
the overall SO 2 emissions. The use of fuels containing high alkaline ash is also recom-
mended because the natural desulfuration of the flue gas occurs during the combustion,
resulting in lower SO 2 emissions (European Commission, 2006).
The use of a low sulfur-containing fuel is a desirable option, but it is not feasible in
most industrial processes. The higher costs associated with cleaner fuels and the