Dr. Hubert Baier General Manager - Europe

Capacity Building for the

Improvement of the Air Quality

SOx - Basics Lima, 24.06.2016

2

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.

Emission Limit Values (Large Combustion Plant Derictive)

8

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

On a power plant

12

Temperature, Time and Turbulance

…is required for an excellent combustion and

a minimum of pollutants…

13

When fuels begin to burn…

14

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

Desulphurization of Hydrocarbons

23

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

Credits: CEMBUREAU

The cement manufacturing process

…starts in the quarry! Credit: Robert Mehl/ Aachen

The cement manufacturing process

Excavation, Crushing and blending Caterpillar

Hazemag

TKIS

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