The Air Products Vattenfall Oxyfuel CO 2 Compression and Purification Pilot Plant at Schwarze Pumpe

Transcription

1 The Air Products Vattenfall Oxyfuel CO 2 Compression and Purification Pilot Plant at Schwarze Pumpe Vince White, Andrew Wright Air Products Stephanie Tappe, Jinying Yan Vattenfall 3 rd Oxyfuel Combustion Conference Ponferrada, Spain 9 th -13 th September,

2 Outline Overview of The Air Products Vattenfall Oxyfuel CO 2 Compression and Purification Pilot Plant The ACPP Issues to be Investigated by the ACPP The Experimental Programme Warm-End Parametric Testing Sour Compression Reaction Modelling Cold-End Material and Energy Balances CO 2 Phase Equilibrium Study Mercury and Water Removal Corrosion Conclusions 2

3 Overview of The Air Products Vattenfall Oxyfuel CO 2 Compression and Purification Pilot Plant The ACPP 1 MW th equivalent slipstream taken from Vattenfall s OxPP before and/or after the flue gas desulphurisation unit Operated over 2 years Designed to demonstrate three concepts that Air Products have developed Warm End CO 2 (Returned to OxPP) Cold End Flue Gas Cooler & Condenser Sour Compression TSA & Mercury Removal Auto-Refrigerated Inerts +O 2 Removal Process Condensate Collection Process Condensate Condensate Collection Process Condensate Air Products PRISM Membrane Inerts Vent CO 2 /O 2 Recovery 3 O 2 and CO 2 Rich Stream

4 Issues to be Investigated by the ACPP (See OCC1 Presentation, September 2009) Cooler & Condenser Condensate Collection Sour Compression Condensate Collection TSA & Mercury Removal Auto-Refrigerated Inerts +O 2 Removal Process Air Products PRISM Membrane 1. Flue gas cooler-condenser performance in a more acidic environment 2. Sulphur and nitrogen oxidation and acid removal 3. CO 2 VLE 4. CO 2 Freeze-out 5. Membrane performance 6. Dynamics of the system start-up, shutdown, varying feed compositions 7. Mercury behaviour and distribution in the process. 8. Dehydration. Performance of TSA adsorbents 9. Potential for corrosion 4

5 The Experimental Programme Experimental programme carried out in collaboration between Air Products and Vattenfall - Commissioning lessons learnt and initial results - Baseline testing over the entire process mass and heat balance - Parametric testing on the Warm End sensitivity to key variables ACPP Integration with the OxPP - The ACPP could only operate when the OxPP was running and this limited available testing time - Two different burners fitted to the OxPP and these gave different flue gas compositions to the ACPP Analysis - Accurate liquid and gas phase analysis was critical - Reactions in sample lines needed to be accounted for CO 2 VLE separate laboratory study conducted to check accuracy 5

6 Warm-End Parametric Testing 6

7 Warm-End Parametric Testing 42 tests performed Results presented at GHGT11, November 2012 Parameter Units Range Flue Gas from Upstream of OxPP FGD % Flue Gas Flow Rate Nm 3 /h bar Column Operating Pressure barg bar Column Operating Pressure barg Compressor Discharge Temperatures o C Column Discharge Temperatures o C bar Column Make-up Water Flow Rate kg/h bar Column Recycle Water Flow Rate kg/h bar Column Make-up Water Flow Rate kg/h bar Column Recycle Water Flow Rate kg/h

8 Flue Gas from Downstream of FGD bar 3 15 bar 4 30 bar 5 30 bar 6 FGCC Comp. Column Comp. Column Measured Concentrations (ppm, dry) HCl SO NO NO N 2 O

9 SO 2 removed from ACPP Inlet to Outlet of 15 bar column (%) Flue Gas from Upstream of FGD Burner 1 (400 ppm NO x ) Burner 2 ( ppm NO x ) Feed SO 2 /NO x Ratio with Constant 2000 ppm SO Feed SO 2 /NO x Ratio with Constant 295 ppm NO x The SO 2 concentration of the incoming flue gas to the ACPP can be varied by taking flue gas from before the OxPP FGD, after the FGD, or a mixture of both. NO x to the ACPP dependent on burner operation - Typically ppm for most tests These results confirm the importance of NO x in the flue gas to the removal of SO 2 from the flue gas Graph at constant NO x shows lower performance as operating conditions chosen resulted in N 2 O formation 9

10 Sour Compression Reaction Modelling 10

11 Updated NO x - SO x Reaction Network Stoichiometry Phase 2 NO + O 2 2 NO 2 V 2 NO 2 N 2 O 4 V N 2 O 4 + H 2 O HNO 3 + HNO 2 L 2 HNO 2 NO + NO 2 + H 2 O L 4 HNO 2 2 NO + N 2 O H 2 O L SO 2 + H 2 O H 2 SO 3 L 2 HNO SO 2 + H 2 O 2 H 2 SO 4 + N 2 O L 2 HNO H 2 SO 3 2 H 2 SO 4 + N 2 O + H 2 O L 2 HNO 2 + SO 2 H 2 SO NO L 2 HNO 2 + H 2 SO 3 H 2 O + H 2 SO NO L 2 NO 2 + H 2 O HNO 3 + HNO 2 L Green propagates NO x redox cycle Red terminates NO x redox cycle NO + O 2 NO 2 / N 2 O 4 + H 2 O HNO 2 + HNO 3 + SO 2 / H 2 SO 3 NO + NO 2 / N 2 O 4 + SO 2 / H 2 SO 3 H 2 SO 4 + NO H 2 SO 4 + N 2 O 11

12 15 bar Column Model and Experiment NO NO 2 50 Model NO (ppm) Model NO 2 (ppm) Model SO 2 (ppm) Experiment NO (ppm) SO Experiment SO 2 (ppm) Experiment NO 2 (ppm) Comparison of analyser and model results for the outlet of the 15 bar column Includes rigorous modelling of reactions in the sample lines No change was made in reaction rate parameters used in the model which were derived from earlier lab-scale data

13 Cold-End Material and Energy Balances: Early Baseline Tests 13

14 Feed Flue Gas CO 2 Concentration (%, dry) Feed Composition Variability Typical ACPP CO 2 feed composition variation over 9 days: OxPP was turned down at night; air ingress to the OxPP becomes more significant at lower rates Time (hours) Typical variation over 7 hours at constant conditions Feed Flue Gas CO 2 Concentration (%, dry) CO 2 Product N 2 and O 2 (ppm, dry) Time (hours) O₂ N₂ 14 however, CO 2 product composition was relatively steady Time (hours)

15 Low Purity CO 2 Material and Heat Balance 87.3% CO 2 recovery, but preliminary study. Plant not optimised Good match of model results with product compositions and flows validates VLE Feed N 2 -Rich Vapour CO 2 -Product - Expt. Mod. Expt. Mod. CO 2 % O 2 % N 2 % Flow % Hot Stream Cold Streams 15 Need to add significant heat ingress to model in order to match experimentally measured temperatures Temperature ( C) Low Pressure CO Duty Medium Pressure CO 2

16 High Purity CO 2 Material and Heat Balance Feed N 2 -Rich Vapour CO 2 -Product 81.4% CO 2 recovery, but plant not optimised Model set up to match O 2 in CO 2 product Learnt a great deal about controlling these processes - Expt. Mod. Expt. Mod. CO 2 % O 2 % ppm 167 ppm N 2 % ppm 182 ppm Flow % Temperature ( C) Hot Stream Cold Streams Reboiler Medium-PressureCO Low-Pressure CO Duty 16

17 Additional Issues Investigated 17

18 CO 2 Phase Equilibrium Study Acquire Experimental K-values of NO, NO 2 /N 2 O 4, N 2 O, and SO 2 Confirm VLE from open literature for O 2 and CO (considerable data exist for N 2 and Ar) VLE measurements completed and thermo model updated O 2 -CO 2 : excellent agreement with published data; improved accuracy using data in this work CO-CO 2 : good agreement with reported data at lower temperatures; improved accuracy from this work at higher temperatures NO-CO 2 : No previous experimental data; VLE behavior similar to N 2 - CO 2 and O 2 -CO 2 N 2 O-CO 2 : No previous experimental data; azeotrope at -50 o C; CO 2 relative volatility close to unity SO 2 -CO 2 : No previous experimental data; lower non-ideality than expected NO 2 -CO 2 : No previous experimental data; lower non-ideality than expected 18

19 Mercury Most of the mercury appears to removed by the FGCC when running on flue gas upstream of the FGD (high SO 2 ) Substantially all the remaining mercury then removed with the acid condensate formed at higher pressure However, limited mercury sampling was conducted and we did see evidence at times of at least some Hg getting to the exit of the TSA dryer (inlet of the Hg guard bed) Water Removal SO 2 found to reduce water capacity of TSA adsorbent: blocks the openings to the microporous crystals SO 2 is irreversibly bound to the adsorbent NO x doesn t seem to have too much of an effect on the drying performance: Reversible adsorption 19

20 Corrosion Corrosion has only been a problem where it should have been expected to have been a problem (See OCC2 Presentation, September 2011) - Important to understand where condensation occurs in the process, when SO 2 and/or NO x are still present in the flue gas - Important to check all equipment materials of construction match specifications 15 bar Column Sump Most coupons just as shiny as they were when they were new However, as expected, we have seen attack on corrosion coupons that are in the chloride containing part of the system - Which is why we have made the dirty end of the FGCC out of fibreglass FGCC Sump 20

21 First demonstration of Sour Compression in representative equipment at the Air Products Vattenfall Oxyfuel CO 2 Compression and Purification Pilot Plant First demonstration of auto-refrigerated inerts removal Learned many lesson relevant to full scale plant design and operation Results allow refinement of sour compression modelling

22 In early 2013 Vattenfall and Air Products decided to conclude their joint R&D program on the ACPP Air Products has developed commercial offerings for CPU plants on demonstration plants based on the results and experience from the Air Products Vattenfall Oxyfuel CO 2 Compression and Purification Pilot Plant This marks the end of 8 years of fruitful and enjoyable collaboration 22 Thanks to Vattenfall for over a decade of leadership and enthusiasm for Oxyfuel CO 2 Capture

23 Thank you tell me more 23