- An experimental study

Transcription

1 The Sulphur Mass Balance in Oxy-Fuel Combustion of Lignite - An experimental study D. Fleig, K. Andersson, D. Kühnemuth, F. Normann, F. Johnsson, B. Leckner Division of Energy Technology, Department of Energy and Environment, Chalmers University of Technology, Göteborg,Sweden

2 Introduction - Aims of the work Quantify sulphur sinks Are there differences in sulphur chemistry between air and oxy-fuel combustion?

3 Motivation of the work Lowered dso 2 emissions i in literature t Design of the flue gas cleaning Sulphur self-retention of the ash SO 2 concentration influences corrosion

4 Experiments - Chalmers 100kW oxy-fuel test unit

5 Schematic of the test unit Fuel T Oxidiser O 2 T Preheater (Air) Dry flue gas recycle Stack Fu urnace T Cyclone T Flue gas cooler T Fabric filter T Wet flue gas recycle Flue gas condenser T Bottom ash Cyclone Cooler Filter Gas Condenser ash ash ash sample water SO 2, CO 2 O 2 and CO

6 Sulphur mass balance Sulphur mass balance: Fuel Bottom ash Cyclone Cooler Filter Gas Condenser ash ash ash sample water Sulphur ash mass flow:

7 Determination of S-flows Sulphur ash flows: measured weighed (balance) calculated sulphur mass concentration Residual ash flow: Fuel ash flow

8 Determination of S-flows Sulphur flue gas flow: Sulphur fuel flow: Conversion of fuel-s to SO 2 Sulphur water flow:

9 Test cases Air fired case Dry oxy-fuel case OF35 Wet oxy-fuel case OF43w Roughly same max. temperatures In all test cases: Predried Lausitz lignite 13kg/h, 76kW

10 Fuel analysis (Lausitz lignite)

11 Results - Conversion to SO 2 / SO 2 concentrations ppm (dry) 500 ppm (wet) 1870 ppm (dry) 1600 ppm (wet) 1960 ppm (dry) 1300 ppm (wet)

12 Ash flows / S-concentrations 9-15% S 8-17% S 10-18% S 3.0% S 3.6% S 3.7% S 6.6% S 6.5% S 6.8% S

13 Sulphur flow in ash

14 Sulphur mass balance Air OF35 Sulphur mass flow in the fuel is set to 100% OF43w

15 Conclusions Lowered emission i of SO 2 by unit energy in oxy-fuel combustion compared to air firing More than 3 times higher SO 2 concentrations in the flue gas from oxy-fuel combustion Sulphur mass flow in the ash is higher in oxyfuel compared to air firing Sulphur mass flow in condenser water is low

16 Ongoing work and future work Clarify the gap in the mass balance Parameter studie SO 2 emissions Limestone + lignite SO 3 measurements Particle sampling from the combustion zone

17 Vattenfall AB is acknowledged for financial support Thank you for your attention!

18 Sulphur balance H 2 SO 4 Condensation Sulphur in fuel Sulphides (FeS 2 ) sulphates SO 3 SO 2 Reactions with ash to Na 2SO 4 K 2SO 4 4, CaSO 4, MgSO 4 Organic compounds SO 2 and 01 0,1 5% 5%SO 3 1 st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009

19 Fate of sulphur during coal combustion weiss nicht ob das mit Sulphur in coal: soll/kann Pyrite (FeS 2 ), organically bound sulphur,... Combustion Gases: SO 2, SO 3, H 2 S,... Sulphur in ash: Not converted Caputred (sulphates) 1 st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009

20 Sulphur release, laboratory conditions

21 Discussion Lower conversion of ffuel-s Sto SO 2 Higher sulphur ash mass flows Possible reason: SO 2 concentration affect the ash self retention However a higher difference in oxy-fuel Difficult at do sulphur mass balance Difficult to get residual ash samples Cyclone wirkungsrad war niedriger

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23 Sulphur release, laboratory conditions

24 Sulphur mass balance SO 2 with NDIR instrument t (NGA 2000) Ash amount Bottom and cyclone ash were weighed Residual ash by difference Sulphur in ash and fuel Standdard method SS Sulphur in condenser water Durch diese Sachen schnell durchgehen. Solubilize with nitric acid ICP-OES inductively coupled plasma - optical emission spectrometer 1 st Oxy-fuel Combustion Conference, Cottbus, 8th -11th September 2009

25 Sulphur release from ashes, laboratory conditions