energy and environment - boun.edu.trweb1.boun.edu.tr/halimgurgenci/l10_1.pdf · 2014. 8. 25. ·...

©2006 Halim Gürgenci, The University of Queensland (Australia) and Bogazici University (Istanbul, Turkey)

Energy and Environment

Professor Halim Gürgenci(visitor from the University of Queensland)

Rm 4245; Phone : (212) 359 [email protected]


Module 10

Environmental Consequences of using Fossil Fuels


Environmental Effects• Air pollution

– Volatile and particulate emissions– Acid deposition– Local haze, smog and loss of visibility

• Water pollution– Mine drainage– Solid waste from power plants– Water use and thermal pollution– Deposition of airborn toxic pollutants on surface waters

• Land pollution– Rehabilitation needs after surface mining– Subsidence caused by underground mining


Emissions

• Volatile emissions– SO2

– NOx (NO + NO2)– CO

• Particulate matter• Toxic pollutants

– Pb, Hg, As, Cu, Mn, Ni, Va, Zn, Ba, Bo, Cr, Se, Cl, HCl, benzene, asbestos, vinyl chloride, pesticides, radioactive substances, and other pollutants


SO2 emissions

• All sulphur in the fuel burns and forms SO2

• If the amount of sulphur in the fuel is S% and the fuel is being burned up at the rate of FR kg/s, the SO2 emission rate is calculated as

2

2

SOSO

S

E S FR= × ×M

M


NOx, CO, and PM emissions

• The NOX, CO and PM emissions cannot be based on the fuel composition as done for the SO2 emissions

• These depend on the combustion process not the composition of the fuel

• Therefore, they can only be determined by analysing the stack gas


Turkish General Industry Emission LimitsNormal işletme şartlarında ve haftalık iş günlerindeki işletme

saatleri için kütlesel debiler (kg/saat) Emisyonlar

Bacadan Baca Dışındaki Yerlerden Toz 15 1.5 Kurşun 0.5 0.05 Kadmiyum 0.01 0.001 Talyum 0.01 0.001 Klor 20 2 Hidrojen klorür ve Gaz Halde İnorganik Klorür Bileşikleri

20 2

Hidrojen florür ve Gaz Halde İnorganik Florür Bileşikleri

2 0.2

Hidrojen Sülfür 4 0.4 Karbon Monoksit 500 50 Kükürt Dioksit 60 6 Azot Dioksit [NOx (NO2 cinsinden)] 40 4 Toplam Uçucu Organik Bileşikler 30 3 Not : Tablodaki emisyonlar tesisin tamamından (bacaların toplamı) yayılan saatlik kütlesel debilerdir.

Çevre ve Orman Bakanlığından: Endüstri Tesislerinden Kaynaklanan Hava Kirliliğinin KontrolüYönetmeliği, Resmi Gazete, 22 Temmuz 2006 CUMARTESİ, Sayı : 26236


Turkish Power Plant Emission Limits

Old plants

New plants New plants

<20000 >20000 New Plants

<20000 20000-50000

>50000 and New Plants

Solid Fuel Fired Plants 250 150 800 - 3200 2000 - 3200 1000

Liquid Fuel Fired Plants 110 110 800 - 3200 1700 - 1700 800

Gas Fired Plants 10 10 500 60 60 60 60 60 60

NOX Emissions mg/Nm3

Remaining Operating Hours Remaining Operating Hours

500 100 - -

1000 175 - -

1000 250 15 100

>300 MWtOld plants <300 MWt

CO Emissions mg/Nm3

F compound Emissions mg/Nm3

CL compound Emissions mg/Nm3

SO2 Emissions mg/Nm3Combustion

plantsDust

Emissions mg/Nm3


The Concentration Unit, mg/Nm3

the N term is an abbreviation of norm or normal. "Normal, in this connection, means a temperature of 0 degrees Celsius and a pressure of 1.013 bar, the conditions at which one mole of an ideal gas has a volume of 22.413837 liters."


US Emission LimitsPollutant Fuel g/GJ Heat InputSO2 Coal 516

Oil 86Gas 86

NOx Coal (bituminous) 260Coal(subbituminous) 210Oil 130Gas 86

PM All 13

Source: Table 9.1, Fay & Golomb, Energy and Environment


US 2000 National Air Quality Standards (NAAQS)

Pollutant ppmV μg/m3CO

8-h average 9 100001-h average 35 40000

NO2Annual arithmetic mean 0.053 100

SO2Annual arithmetic mean 0.03 80

24-h average 0.14 365PM (d<10 μm)

Annual arithmetic mean 50

Limits

Source: Table 9.3, Fay & Golomb, Energy and Environment


Haze and Lack of Visibility

A pair of photos taken in Beijing by Bobak Ha'Eri in August 2005. He was in Beijing twice over a period of a week and a half, both times at the same hotel and in approximately the same room. The photo on the right was taken during a sunny, otherwise clear day on the first visit. The photo on the left was on the second visit, after it had rained for approximately 2 days. Both of these photos were taken in the morning around the 07:00-08:00 hour. Bobak Ha'Eri reported that during the day that he took the second photo, it was quite tiring to walk around(wikipedia).


Air Quality Modelling

Modelling of a Steady-State Point Source


The Gaussian Plume

H Stack Height, m

ΔH Plum rise, m (to be addressed later)

σ Dispersion coefficients (next two slides)

Fay&Golomb, Energy and Environment, Figure 9.1


Horizontal Dispersion Coefficient

The six curves correspond to six atmospheric stability categories A (extremely unstable) through F(very stable).



Vertical Dispersion Coefficient

The six curves correspond to six atmospheric stability categories A (extremely unstable) through F(very stable).



Pasquill-Gifford Stability CategoriesCategory Stability

A Extremely unstableB Moderately unstableC Slightly unstableD NeutralE Slightly stableF Very stable

Fay&Golomb, Energy and Environment, Table 9.5


Stability and Wind Speed

Surface Wind, m/s Day, moderate sunlight Night, thinly overcast<2 B D-F2-3 C E3-5 C D5-6 D D>6 D D

Check Fay&Golomb, Energy and Environment, Table 9.5, for categories corresponding to other weather conditions.


Gaussian Plume Equation

( )22

2 212

( , , )2

y z

z Hy

p

y z

Qc x y z e

uσ σ

πσ σ

⎛ ⎞−⎜ ⎟− +⎜ ⎟⎝ ⎠=

The time averaged mass concentration c for the pollutant p at a downwind distance x from a point source of pollutant emitted at Qp g/s, at the height h, and at the wind speed u is given by the following equation:

This is for elevated points. At the ground level, if it is assumed that the pollutant molecules are not absorbed at the ground but reflected back, the factor 2 disappears:

2 2

2 21 ( )2( , , ) y z

y z Hp

y z

Qc x y z e

uσ σ

πσ σ

⎛ ⎞−⎜ ⎟− +⎜ ⎟⎝ ⎠=


Δh ← Briggs plume rise equationThe US Environmental Protection Agency (EPA) recommends the following relations for the plume rise.

For unstable and neutral conditions (A-D) For stable conditions (E-F)

3/5 1 4 3

3/ 4 1 4 3

2

38.71 5521.425 55

4s a

s ss

F u if F m sh

F u if F m sT TF gv D

T

−

−

>Δ =

≤−

=

g = 9.81 m/s2 vs = Flue gas exit speed, m/s

Ds = Stack diameter, m Ts = Flue gas exit temperature, oK

u = Wind speed at stack height, m Ta = Ambient temperature at stack height, oK

1/3

1

2.61

a

FhuS

TS g Tz

−

⎡ ⎤Δ = ⎢ ⎥⎣ ⎦∂

=∂

The vertical temperature gradient is 0.02 oK/m for category E and 0.035 oK/m for category F.


Secondary Pollutants

Photo-oxidants


Photo-oxidants• These are produced by the sunlight acting on the

primary polutants produced during fossil fuel combustion

• The most important photo-oxidant is ozone, O3• The ozone is produced by NOx and other volatile

organic compounds (VOC)• The US limits on ozone is 120 ppbV, 1-h maximum

concentration• Modelling of atmospheric O3 is much more

complicated than modelling the dispersion of a primary pollutant such as SO2


Acid Deposition

energy and environment - boun.edu.trweb1.boun.edu.tr/halimgurgenci/l10_1.pdf · 2014. 8. 25. ·...

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