Post Combustion CO 2 Capture Scale Up Study

Transcription

1 Post Combustion CO 2 Capture Scale Up Study Prachi Singh and Mike Haines International Greenhouse Gas R&D programme 6 th International Conference on Clean Coal Technologies (CCT 2013) th May 2013 Thessaloniki, Greece PRACHI.SINGH@IEAGHG.ORG

2 Challenges for Post Combustion Capture (PCC) High energy requirement High capture costs NH 3 Uncertainties of the environmental impacts Challenge related to the scale up CO2 Air Heater Boiler Selected Catalyst Electrostatic Reactor Precipitator (SCR) (ESP) Source: Mitsubishi Heavy Industries Flue Gas Desulphurization (FGD) Carbon Dioxide Capture Stack

3 Post Combustion CO 2 Capture Scale-up This study define different technical challenges related to conventional scale-up and full scale operational requirements for PC capture technologies Focus of this study: Technical & Technical Performance challenges Sensitivity to Operational risks gaps several variables are evaluated Suggested PCC Scale-up Strategy for future development This study was undertaken by Black & Veatch, USA

4 PCC Scale-up Study Technical challenges associated with PCC full scale design for o Supercritical Pulverized Coal (SCPC) 900MW o Natural Gas Fired Combined Cycle (NGCC) 800MW Basis of the Study o With 90% CO2 capture o Selective Catalytic Reduction (SCR) for both SCPC and NGCC power plants with 80-84% NOx removal efficiency o Particulates were removed by Pulse Jet Fabric Filter (PJFF) for SCPC with 90% removal efficiency o Wet Flue Gas Desulphurisation (WFGD) with Limestone Forced Oxidation (LSFO) for SCPC with SO2 removal efficiency of 97.5% & additional SO2 polishing scrubber

5 Major equipment for SCPC with CO 2 capture 12 mole%co 2 900MW SCPC Power plant 1 SCPC steam generator 1 Steam turbine generator 1 SCR 1 Fabric filter 4 Flue gas fans 1 Primary FGD 1 Polishing FGD 2Condensers 1 Cooling tower 5mole%O 2 CO 2 Capture Unit 11 Absorber, 28m height 2 Stripper columns, 23m height 8 Reboilers 4 Stripper overhead coolers 3 Heat exchangers 4 Amine pumps p 5 Lean amine coolers 5 Side draw coolers 2 Water wash pumps 1 Water wash coolers CO 2 Compression and Dehydration 2 Three stage CO 2 compression train 2CO 2 Dehydration unit

6 Major equipment for NGCC with CO 2 capture 4 mole% CO 2 800MW NGCC Power plant 2GCl G-Class Gas turbine generators 2 HRSG (w/scr) 1 Steam turbine generator 1 Condenser 1 Cooling tower 3Quench cooler heat exchanger 12 mole% O 2 CO 2 Capture Unit CO 2 Compression 1 Absorber, 28m height and Dehydration 1 Stripper column, 23m height 4 Reboilers 2 Stripper overhead coolers 2 Heat exchangers 4 Amine pumps p 1 Lean amine coolers 2 Quench cooler 1 Side draw coolers pumps 2 Water wash pumps 2 Flue gas fans 2 Water wash coolers 2 Three stage CO 2 compression train 2 CO 2 Dehydration unit

7 Impact on Electricity Output NGCC NGCC with UNIT SCPC SCPC with CO 2 CO 2 Net Plant Thermal efficiency % CO 2 Capture % No 90 No 90 Steam Turbine Generators MW Gas Turbine Generators MW (total) Total Gross Output MW Auxiliary Electric Load Power Block MW Flue Gas Fans MW N/A 26.1 Air Quality Systems MW CO 2 Capture MW N/A 5.2 N/A 3.6 CO 2 Compression MW N/A 75.0 N/A Total Auxiliary Electric Load MW Net Plant Output MW Energy Penalty % N/A N/A CO 2 for Transport t/h N/A 629 N/A 250 CO 2 to Atmosphere t/h

8 Impact on Utility Consumption and dwaste Generation UNIT SCPC SCPC with NGCC CO 2 CO 2 PLANT UTILITY CONSUMPTION Makeup Water Cooling Tower m 3 /h 9,600 12,500 4, ,400 Cycle Makeup m 3 /h NGCC with CO Advanced Amine Solvent (1) kg/h N/A 283 N/A 210 CO 2 Dehydration Adsorbent (2) kg/h N/A 16 N/A 7 PLANT WASTE PRODUCTION Wastewater Cooling Tower Blowdown m 3 /h 1,900 2, ,300 CO 2 Capture Wastewater (3) m 3 /h N/A (Note 3) N/A (Note 3) Amine Waste kg/h N/A 146 N/A 108 Notes: 1. Amine degradation includes degradation from oxygen and sulfur, but excludes NO x. 2. Bed replacement every 3 to 5 years. 3. Minimal wastewater discharge. Water condensed from flue gas and CO 2 streams are used for cooling tower makeup.

9 Some Key Results (1): Technical Assessments Steam system, Turbine, Condenser SCPC case steam is extracted from the cross-over piping and de-superheated to saturation NGCC case a quarter of the steam is from HRSG and the LP turbine Minor modifications to steam turbine design and HRSG Opportunity optimization of steam extraction point and condensate return High gas turbine back pressure required to lower footprint and complexity Plant stiffening is required for boiler ductwork and flue Plant stiffening is required for boiler, ductwork and flue gas equipment

10 Some Key Results (2): Technical Assessments Size and Construction of Absorber and Stripper unit Single rectangular concrete absorber b with multiple l parallel l sections with random packing of 17.8 m x 17.8 m x 28 m More precision required for correct internal dimensions and feeds for the absorber The size of strippers for SCPC and NGCC cases was 2x7.2 m and 1x 7.0 m columns and approx. 23m height respectively. Main challenge for stripper is its transportation due the large size; but this issue is very site specific

11 Some Key Results (3): Technical Assessments Flue gas bypass Required during start-up, shutdown and other upset conditions Cost to construct and maintain a flue gas bypass system Pressure loss in absorber column Transition of operation in and out of bypass Proper coordination of flue gas and boiler draft pressure during transition phase Flue gas fan size 4 axial ID fans for SCPC and 2 axial ID NGCC cases No technical challenges; Higher flow fans will reduce cost

12 Some Key Results (4): Technical Assessments Emission Issues Nitrosamine Emissions & Regulations IEAGHG study 2012/07 on Gaseous emission was focused on amine emissions Sustainable way of amine waste disposal; IEAGHG will commission study on Reclaimer waste disposal Plume visibility ibilit may be an issue because of the much lower release temperature Addition of a superheater to the vent stream can be an option

13 Secondary Issues Increase in cooling water The cooling requirements approx. 20% higher for SCPC & approx. 40% higher for NGCC case Cooling system design is very site specific and economics depends ds on the price of available a ab water Flue Gas Desulphurization Wet flue gas desulfurization (WFGD) and a polishing scrubber system were used Integration of primary and polishing FGD stages into a single SO 2 absorber system will reduce the footprint of the flue gas cleaning.

14 Other Points CO 2 Compression issues are mainly related to the availability of the plant and its start-up requirements Solid adsorbents technology is found to be suitable for CO 2 drying requirement 2 y g q Large size required for Heat Exchangers required and multiple units will be needed Integration of CO 2 capture process controls with the main power plant distributed control system

15 Size Breakpoints No significant size breakpoints; Main issues identified are as follows: Above Power Plant size MW Single absorber may no longer be reasonable Second stripper would be required for a NGCC plant Third stripper required for a SCPC plant CO 2 compressors Size is limited to around 75,000kW

16 Future Evaluation Process Units Evaluation of the design change in gas turbine with an increased exhaust pressure up to 18kPa (g) for NGCC Evaluation of the cost, safety and permit issues for CO 2 stack discharge for extended period of time for large scale post combustion CO 2 capture system Evaluation and optimization of the integrated primary and polishing FGD stages into single SO 2 absorber system Investigate effect of rectangular shape absorber on its hydrodynamics Evaluation of the CO 2 capture plant control system integration to the main power plant DCS system

17 Future Evaluation Process Issues Evaluation for amine emission reduction & amine waste disposal Operational requirement during startup and shutting down of highly integrated power plant with CO 2 capture Evaluation of the operation flexibility for large scale CO 2 post combustion capture plant application in power plants

18 PCC Development Strategy Solvent Development -Absorption rate -Sensible heat requirement Environmental Issues -Solvent emissions limitsit -Solvent coproduct emissions and exposure limits -Flue gas buoyancy y and dispersal studies Equipment design -Construction and transport of equipment -Heat integration -Heat exchanger optimization -Modified equipment designs -Improved controls

19 Conclusions Proces ss Unit Proc cess Issu ues Barrier Technical Breakthrough Complexity of Development Steam Generation Steam Extraction Flue gas bypass Cooling ID Fans Absorber Heat exchanger Stripper CO 2 Compression CO 2 Drying Amine Emission Capture plant Startup & Shutdown Retrofit Advanced Control System Cost

20 Recommendations Amine emission issue and disposal of amine based waste Cycling, part-load, intermittent operation, start-up, shut-down operation issues CO 2 large scale venting or depressurizing HP pipeline pp issues related to safety and permits Evaluation of mid and peak merit market operation, following a specific weekly demand curve Identifying the capacity limits and ramping capabilities of de t y g t e capac ty ts a d a p g capab t es o equipment like the stripper and reboiler

21 REFERENCE IEAGHG Report No.: For any questions: Prachi Singh