Capacity Building for the Improvement of the Air Quality

Transcription

1 Capacity Building for the Improvement of the Air Quality SOx - Basics Lima, Dr. Hubert Baier General Manager - Europe

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3 Harming effects SO 2 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. 3

4 Harming effects The air pollution by SO 2 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/ m 3 of air implies a potential risk for human health, but also for fauna, where 0.2 µg/m 3 becomes dangerous. SOx and sulphuric acid (H 2 SO 4 ) are related with the damage and destruction of vegetation, soil deterioration, erosion and early weathering of concrete and limestone. Credits: Nino Barbieri/ Wikipedia 4

5 German legal framework 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. 5

6 Standard fuels by legal definition 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 6

7 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, NO x, SO 2 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.

8 Emission Limit Values (Large Combustion Plant Derictive) 8

9 Parameter and limited values Parameter Dimension Incineration and Co-Incineration Half-hourly average Daily average Annual average Total Dust mg/nm gaseous Chlorine and its components, quoted as HCl gaseous Fluorine and its components, quoted as HF mg/nm mg/nm SO x, quoted as SO 2 mg/nm Organic components, quoted as C total mg/nm Carbon monoxide mg/nm NO x, quoted as NO 2 Waste incinerator power plant >100MW Cement kiln mg/nm ) / ) /200 1) Clause for transitional period for old kilns

10 kt German Trend and Sectors of SOx emission total emission of SO

11 SOx-emission 2013 in kt German Sectors of SOx emission (2013)

12 On a power plant 12

13 Temperature, Time and Turbulance is required for an excellent combustion and a minimum of pollutants 13

14 When fuels begin to burn 14

15 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

16 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

17 BAT measures for specific fuels Fuel Combi process Thermal efficiency (% net) Hard coal and lignite Hard coal lignite Biomass CHP Dry firing/ wet bottom firing New Existing FBC >41-42 Dry firing/ wet bottom firing FBC >40 42 Stoker fired (CHP) FBC > Gas Motor or turbine >35 17

18 Circulated Fluidized Bed Combustion flue gas (<200 C to gas cleaning) 2-phase-separation (cyclon) steam water lime fuel water steam discharge feed air h+s energieanlagen gmbh/ Freising combustion air (400 C) Spektrum Akademischer Verlag Heidelberg 2003

19 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

20 Coal-fired power plant Energy Emissions Production of plaster Fuels burning process flue gas gas cleaning Flue gas desulfurization gypsum Production of cement Fly ash Production of concrete Bottom ash Road construction

21 Pyrite/ Markasite the natural sources of sulphur The remaining residues will be oxydized as well as to 4 FeS O 2 + E 2 Fe 2 O SO 2 21

22 Desulphurization of Coal When pyrite is tangly incorporated in the coal, it has to be processed by cleaning procedures before utilization Credits: Multotec 22

23 Desulphurization of Hydrocarbons 23

24 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): Mass-% C H N O S Lignite Hard coal Oil S (4.5) Petrol < Wood Gas (CH 4 ) Biogas (CH 4 )

25 Basics on Formation of sulphur oxide S(s) + O 2 (g) -> SO 2 (g); H = kj/mole (32kg) + (2*16kg) -> (64kg resp m 3 ) 2 SO 2 (g) + O 2 (g) -> 2 SO 3 (g); ΔH = kj/ mol The formation of sulphur oxide is an exothermic reaction and the product will emitted as SO 2 and SO 3. Due to unknown portions we call it SOx. SOx formation in combustion processes is different from NOx formation. 25

26 Basics on Formation of sulphur oxides The conversion of sulphur from fuels to SO 2 and SO 3 is usually complete. Due to decreasing temperatures, the ratio of SO 3 to SO 2 in the emissions will increase with the increasing pressure and increasing O 2 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 SO 2 and SO 3 can retain sulfur and sulfates if the temperature is below 1300 C which corresponds with the experiences, respectively of the cement industry. 26

27 Manufacture of cement and concrete Emissions Cement plants Concrete plants Building raw material fuels Clinker burning process Clinker Cement grinding Production of concrete Aggregates Use Leaching Deposition / Recycling Leaching Sulfate carriers other main components Additions Admixtures

28 The cement manufacturing process Credits: CEMBUREAU

29 The cement manufacturing process starts in the quarry! Credit: Robert Mehl/ Aachen

30 The cement manufacturing process Excavation, Crushing and blending Caterpillar Hazemag TKIS

31 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

32 Pyrite/ Markasite the natural sources of sulphur When Pyrite becomes a part of the raw material it will play a matter 32

33 Way of (Pyritic) Sulphur in Direct Operation Expulsion of S 2 - in the preheater Small slip of Fuel SO 2 possible Direct operation Low adsorption on dust Higher emission level Raw Meal Silo S O 2 2 SO 2 SO 2 Dust SO 2 SO 2 + O 2 SO 3 SO 2 SO 3 H 2 O Silo Clinker Credit: TKIS

34 Way of (Pyritic) Sulphur in compound Operation Expulsion of S 2 - in the preheater Small slip of Fuel SO 2 possible Compound operation: Adsorption in the raw mill Lower emission level Mill bypass increase emission level Raw Meal Silo Raw Mix S O 2 2 SO 2 SO 2 Dust SO 2 SO 2 + O 2 SO 3 SO 2 SO 3 Silo Clinker Credit: TKIS

35 SO 2 sorption raw mill Depends on the specific Sulphur load in the mill total emission 30-90% raw mill 40-80% preheater Credit: TKIS 100% S 2- derived SO 2

36 Used tires the additional sources of sulphur Mass- % C H N O S Lignite Hard coal Oil S (4.5) Used tires But when tires are fed they will play a bigger role due to 36

37 Ring formation The kiln operator should have vital interest in a smooth kiln process! As a side effect the SO 2 emissions will be at its lowest level. If this level is still too high, reduction measures have to be envisaged. Ring formation Credits: Cemnet, Solidia, ElectroPhysics 37

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