Why NOx & SOx Reduction?

What is NOx on Wikipedia ?

12NOx is a generic term for the mono-nitrogen oxides NO and NO2 (nitric oxide and nitrogen dioxide). They are produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures. In areas of high motor vehicle traffic, such as in large cities, the amount of nitrogen oxides emitted into the atmosphere as air pollution can be significant. NOx gases are formed whenever combustion occurs in the presence of nitrogen – as in an air-breathing engine; they also are produced naturally by lightning. In atmospheric chemistry, the term means the total concentration of NO and NO2. NOx gases react to form smog and acid rain as well as being central to the formation of tropospheric ozone.

12NOx should not be confused with nitrous oxide (N2O), which is a greenhouse gas and has many uses as an oxidizer, an anesthetic, and a food additive.

NOy (reactive, odd nitrogen) is defined as the sum of NOx plus the compounds produced from the oxidation of NOx which include nitric acid.

Environmental Effect of NOx.

12NOx reacts with ammonia, moisture, and other compounds to form nitric acid vapor and related particles. Small particles can penetrate deeply into sensitive lung tissue and damage it, causing premature death in extreme cases. Inhalation of such particles may cause or worsen respiratory diseases, such as emphysema or bronchitis, or may also aggravate existing heart disease.

NOx reacts with volatile organic compounds in the presence of sunlight to form ozone. Ozone can cause adverse effects such as damage to lung tissue and reduction in lung function mostly in susceptible populations (children, elderly, asthmatics). Ozone can be transported by wind currents and cause health impacts far from the original sources. The American Lung Association estimates that nearly 50 percent of United States inhabitants live in counties that are not in ozone compliance.

NOx destroys ozone in the stratosphere. Ozone in the stratosphere absorbs ultraviolet light, which is potentially damaging to life on earth. NOx from combustion sources does not reach the stratosphere; instead, NOx is formed in the stratosphere from photolysis of nitrous oxide.

NOx also readily reacts with common organic chemicals, and even ozone, to form a wide variety of toxic products: nitroarenes, nitrosamines and also the nitrate radical some of which may cause biological mutations. Recently another pathway, via NOx, to ozone has been found that predominantly occurs in coastal areas via formation of nitryl chloride when NOx comes into contact with salt mist.

NOx should not be confused with nitrous oxide (N2O), which is a greenhouse gas and has many uses as an oxidizer, an anesthetic, and a food additive.

NOy (reactive, odd nitrogen) is defined as the sum of NOx plus the compounds produced from the oxidation of NOx which include nitric acid.

IMO, ISO, UN has been preparing the policy to reduce the amount of Gas emission to protect environment from warming of marines.

NOx Regulation in the world

U.S. / Canada ECAs

Cover areas within 200 nautical miles from land and become effective on 1st, Aug, 2012.
Tier II NOx Regulation enforced from 1st, Jan, 2011 and Tier III NOx regulation will enforce from 2016.

Engine Speed (rpm)

Tier I (~ year 2010)

Tier II (Year 2011~ Year 2015)

Tier III (~Year 2016)

Under 130 rpm

17.0 g/kwh

14.4 g/kwh (15% Reduction Contrast Tier 1)

3.4 g/kwh (80% Reduction Contrast Tier 1)

130 ~ 2,000 rpm

45.n ̄º·²³ g/kwh

44.0 ̄º·²³ g/kwh (15.5% ~ 21.8% Reduction Contrast Tier 1)

9.0 ̄º·²³ g/kwh (80% Reduction Contrast Tier 1)

Over 2,000 rpm

9.8 g/kwh

7.7 g/kwh (21.8% Reduction Contrast Tier 1)

2.0 g/kwh (80% Reduction Contrast Tier 1)

What is SOx on Wikedpia ?

Sulfur dioxide (also sulphur dioxide) is the chemical compound with the formula SO2. At standard atmosphere, it is a toxic gas with a pungent, irritating, and rotten smell. The triple point is 197.69 K and 1.67kPa. It is released naturally by volcanic activity.

Inhaling sulfur dioxide is associated with increased respiratory symptoms and disease, difficulty in breathing, and premature death. In 2008, the American Conference of Governmental Industrial Hygienists reduced the short-term exposure limit to 5 parts per million (ppm)

SOx Regulation

SOx Emission is regulated by sulfur content in fuel and following regulation of sulfur content made agreement in 57th MEPC meeting.

Limit Sulfur content in the word

124.50% (45,000 ppm) – up to 2012 year
123.50% (35,000 ppm) – from 2012 year
120.50% (5,000 ppm) – enforce from 2020 year
12Reviewing the Enforce Date in 2018

ECAs

121.50% (15,000 ppm) by 1st, March, 2010
121.00% (10,000 ppm) from 1st, March, 2010 ~
120.10% (10,000 ppm) from 2015 year

ECA's timetable for NOx and Sulphur content limits

MEPC SO2(ppm)/CO2(%) Regulation

Fuel Oil Sulphur Contents
(% m/m)

Ratio Emission
SO2(ppm)/CO2(% V/V)


4.50

195.0

3.50

151.7

1.50

65.0

1.00

43.3

0.50

21.7

0.10

4.3

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