Capacity Building for the Improvement of the Air Quality … · FBC >41 - 42 lignite Dry firing ......
-
Upload
duongxuyen -
Category
Documents
-
view
213 -
download
0
Transcript of Capacity Building for the Improvement of the Air Quality … · FBC >41 - 42 lignite Dry firing ......
Dr. Hubert Baier General Manager - Europe
Capacity Building for the
Improvement of the Air Quality
SOx - Basics Lima, 24.06.2016
Harming effects
3
SO2 is hygroscopic, and in
the atmosphere it reacts
with humidity to form
sulphuric acid and
sulphurous aerosol.
The intensity of formation of
aerosols and the presents
in the atmosphere depend
on the meteorological
conditions and the quantity
of catalytic impurities in the
air.
In general, the average time of permanence in the atmosphere is
around 3-5 days, so it can be transported to greater distances.
Harming effects
The air pollution by SO2 may effect breathing problems,
cardiovascular diseases, as well as asthma, chronic bronchitis,
morbidity and mortality increase in old people and infants.
A level of 0.3 µg/ m3 of air implies a potential risk for human health,
but also for fauna, where 0.2 µg/m3 becomes dangerous.
SOx and sulphuric acid (H2SO4) are related with the damage and
destruction of vegetation, soil deterioration, erosion and early
weathering of concrete and limestone.
4 Credits: Nino Barbieri/ Wikipedia
German legal framework
5
The erection and operation of
powers plants or cement works
are subject to the provisions of
the Federal Ambient Pollution
Protection Act (BImSchG).
Depending on the type of fuel,
different specifications for the
emission concentrations to be
complied are laid down. If
standard fuels are used
exclusively, the regulations of
the Clean Air Act (TA Luft) are
decisive.
Standard fuels by legal definition
6
natural-born:
• natural gas
• Coal,
• Lignite,
• Peat,
• Charcoal,
• Natural wood (regarding DIN)
• Straw or similar plants (biomass)
• biomass derived oil (palm, rapeseed etc.)
artificial:
• Hydrogen
• Biogas or sewage gas
• Fuel oil (regarding DIN)
• furnace, coke or steel making gas, mining gas (due to limitation of
sulfur contend)
• explicitly not mentioned in annex 4. BImSchV, but in historical terms
• Oil shale
Enforcement of legal framework
Proceeding from this legal
basis, the competent
authorities can order
measurements to be
carried out by accredited
bodies.
Emissions can be
determined both by
continuous and
discontinuous measuring
methods, which are
described in relevant standards.
Continuous measurement is primarily used for dust, NOx, SO2 and
Hg, while the remaining parameters relevant to the ambient pollution
legislation are usually determined discontinuously by individual
measurements. They are converted to reports, which were collated to
the given permissions.
Parameter and limited values
Parameter Dimension Incineration and Co-Incineration
Half-hourly
average
Daily
average
Annual
average
Total Dust mg/Nm3 30 20 10
gaseous Chlorine and its
components, quoted as HCl mg/Nm3 60 10
gaseous Fluorine and its
components, quoted as HF mg/Nm3 4 1
SOx, quoted as SO2 mg/Nm3 200 50
Organic components, quoted as
C total
mg/Nm3 20 10
Carbon monoxide mg/Nm3 100 200
NOx, quoted as NO2
Waste
incinerator
mg/Nm3
100 100
power plant
>100MW 200 100
Cement kiln 8001)/
500 4001)/200
1)Clause for transitional period for old kilns
German Trend and Sectors of SOx emission
10
0
1000
2000
3000
4000
5000
6000
kT
1990 – 2014 total emission of SO2
German Sectors of SOx emission (2013)
11
225.61
60.97
34.89 34.68 31.29 18.14
4.83 2.03 1.25 1.23 0.87 0.20 0.12 0.05 0
50
100
150
200
250
SO
x-e
mis
sio
n 2
01
3 in
kT
Temperature, Time and Turbulance
…is required for an excellent combustion and
a minimum of pollutants…
13
Basics on Formation of sulphur oxide
A complete combustion is characterized by emissions of:
Carbon dioxide, water, ash particles, sulphur oxides, nitrogen
oxides, gaseous halogen hydrocarbons and volatile heavy metals
Emissions from incomplete combustion:
Carbon monoxide, hydrocarbons (organic total C), tar, soot,
unburned particles, polycyclic aromatic hydrocarbons (PAH)
Emissions due to side reactions:
Nitrogen oxides, dioxins
15
Basics
The formation of pollutants in a combustion process is
unavoidable but in practice it can be reduced by
1) optimization of the
combustion process
(primary measures) or
2) exhaust gas cleaning
(secondary measures)
3) use best available technic
16
BAT measures for specific fuels
Fuel Combi process Thermal efficiency (% net)
New Existing
Hard coal and
lignite
CHP 75 – 90 75 – 90
Hard coal Dry firing/ wet
bottom firing 43 – 47
36 - 40 FBC >41 - 42
lignite Dry firing/ wet
bottom firing 42 – 45
FBC >40 – 42
Biomass Stoker fired
(CHP) 75 – 90
FBC >28 – 30
Gas Motor or turbine 36 - 45 32 - >35
17
flue gas (<200°C to gas cleaning)
lime fuel
combustion air (400°C)
discharge
water
steam
2-phase-separation (cyclon)
© Spektrum Akademischer Verlag Heidelberg 2003
Circulated Fluidized Bed Combustion
© h+s energieanlagen gmbh/ Freising
steam
water
feed air
Coal-fired power plant
1. Cooling tower
2. Cooling water pump
3. Three-phase transmission line
4. Step-up Transformer
5. Electrical generator
6. Low pressure steam turbine
7. Boiler feed water pump
8. Surface condenser
9. Intermediate pressure steam turbine
10. Steam control valve
11. High pressure steam turbine
12. Deaerator
13. Feed water heater
14. Coal conveyor
15. Coal hopper
16. Coal pulverizer
17. Boiler steam drum
18. Bottom ash hopper
19. Superheater
20. Forced draught fan
21. Reheater
22. Combustion air intake
23. Economizer
24. Air preheater
25. Precipitator
26. Induced draught (draft) fan
27. Flue gas stack
Coal-fired power plant
Fuels
Emissions
Production
of cement flue gas burning
process gas
cleaning
Production
of concrete
Flue gas
desulfurization
gypsum
Fly ash
Bottom ash Road
construction
Energy Production
of plaster
Pyrite/ Markasite – the natural sources of sulphur
21
The remaining residues will be oxydized as well as to
4 FeS2 + 11 O2 + E → 2 Fe2O3 + 8 SO2
Desulphurization of Coal
22
When pyrite is tangly incorporated in the coal, it has to be
processed by cleaning procedures before utilization
Credits: Multotec
Composition of main fuels
In the European Union all available types of fuels are used. Each
nation focusses on its own local country wide access.
Median composition of fuels (ash free):
24
Mass-% C H N O S
Lignite 58 - 75 0 - 7 0.4 – 1 15 – 35 0.8 – 2.5
Hard
coal
81 – 92 4 - 7 1.5 2 - 10 1 - 2
Oil S 86 - 89 10 - 12 0.005 - 1 0 - 50 0.01 – 2
(4.5)
Petrol 85 15 < 0.004
Wood 47 - 53 5 – 7 0.1 – 1 42 – 46 0.01 – 0.3
Gas (CH4) 93 1 – 14
Biogas (CH4) 50 –
60
Basics on Formation of sulphur oxide
S(s) + O2(g) -> SO2(g); ∆H = -296.7 kJ/mole
(32kg) + (2*16kg) -> (64kg resp. 22.41m3)
2 SO2(g) + O2(g) -> 2 SO3(g); ΔH = -198.2 kJ/ mol
The formation of sulphur oxide is an exothermic reaction and the
product will emitted as SO2 and SO3.
Due to unknown portions we call it SOx.
SOx formation in combustion processes is different from NOx
formation.
25
Basics on Formation of sulphur oxides
The conversion of sulphur from fuels to SO2 and SO3 is usually
complete.
Due to decreasing temperatures, the ratio of SO3 to SO2 in the
emissions will increase with the increasing pressure and
increasing O2 concentration.
In the literature are several kinetic models with complex reaction
mechanisms, but unfortunately the models are effected by the
mineral composition of the ash (e.g. CaO, MgO).
So finally, the concentration of SO2 and SO3 can retain sulfur and
sulfates if the temperature is below 1300°C which corresponds
with the experiences, respectively of the cement industry.
26
Manufacture of cement and concrete
Cement plants Emissions
other main
components
Production
of concrete
Aggregates
Additions
Admixtures
Leaching
Use
Leaching
Deposition /
Recycling Clinker Clinker
burning
process
Cement
grinding
Concrete
plants
Building
Sulfate
carriers
fuels
raw material
The cement manufacturing process is affected to
1) 90 mass-% of raw material and 10 mass-% of fuel as
ingrediens for clinker burning
2) Regarding the cement quality the composition of the entry
raw material and fuel ash have to reach the chemical ratio
3) High mass flow of raw material especially lime, which is
ground to a large surface and thermally high activated
shows effects similar to the dry-sorption gas cleaning in
other industries
4) Hydrocarbons and organic pollutants will be destroyed by
a flame temperature at 2000°C and a retention time larger
than 2s
5) Volatile elements have to be respected
Pyrite/ Markasite – the natural sources of sulphur
32 When Pyrite becomes a part of the raw material it will play a matter…
Way of (Pyritic) Sulphur in Direct Operation
Clinker
Dust
Silo
S2- + 2 O2 2 SO2
H2O
SO
2
Expulsion of S2- in
the preheater
Small slip of Fuel SO2 possible
Direct operation
Low adsorption on dust
Higher emission level
SO2
Raw Meal
SO
2 S
O3
SO2 + O2 SO3
Silo
Credit: TKIS
Way of (Pyritic) Sulphur in compound Operation
Raw Mix
Clinker
Dust
Silo
S2- + 2 O2 2 SO2
SO
2
Expulsion of S2- in the
preheater
Small slip of Fuel SO2 possible
Compound operation:
Adsorption in the raw mill
Lower emission level
Mill bypass increase emission level
Raw Meal
SO
2
SO
2 S
O3
SO2 + O2 SO3
Silo
Credit: TKIS
SO2 sorption raw mill
40-80%
preheater
100% S2- derived SO2
30-90%
raw mill
total emission
Depends on the specific Sulphur load in the mill
Credit: TKIS
Used tires – the additional sources of sulphur
36
Mass-
%
C H N O S
Lignite 58 - 75 0 - 7 0.4 – 1 15 – 35 0.8 – 2.5
Hard coal 81 – 92 4 - 7 1.5 2 - 10 1 - 2
Oil S 86 – 89 10 - 12 0.005 - 1 0 - 50 0.01 – 2
(4.5)
Used
tires
70 - 75 6 - 7 0.5 4 1 – 1.7
But when tires are fed
they will play a bigger
role due to…
Ring formation
37
Ring formation
The kiln operator should have vital
interest in a smooth kiln process!
As a side effect the SO2 emissions
will be at its lowest level.
If this level is still too high,
reduction measures have to be
envisaged.
Credits: Cemnet, Solidia, ElectroPhysics