Evaluation of Reclaimer Sludge Disposal from Post- Combustion CO 2 Capture

Transcription

1 Evaluation of Reclaimer Sludge Disposal from Post- Combustion CO 2 Capture Prachi Singh, IEA Greenhouse Gas R&D Programme, UK Paul Nielsen, University of Texas at Austin Trimeric Corporation, University of Texas at Austin and URS Corporation

2 Reference Cases Capacity (MWe) CO 2 Concentration (mole%) Coal % Natural Gas % Solvent 7m MEA (120 C) 8m PZ (150 C) 7/2m MDEA/PZ (135 C) Flue Gas Lean Loading (mole CO 2 / mole total alkalinity) Rich Loading (mole CO 2 / mole total alkalinity) Solvent Circulation Rate (standard m 3 /h) Coal ,719 Natural Gas ,083 Coal ,641 Natural Gas ,818 Coal ,707 Natural Gas ,105 Solvent inventory: 30 minutes total holdup

3 Amine Losses Thermal Degradation 10 min residence time in stripper packing, sump, & reboiler MEA: 120 C, PZ: 150 C, MDEA/PZ: 135 C Oxidation Function of O 2, T hot of cross exchanger (30 second residence time), catalyzed by metal ions 5 mol% O 2 (11% for NGCC) Nitrosation 1.5 ppmv NO 2 Volatile amine loss/aerosols 1 ppmv after water wash Loss in reclaimer sludge 1 5 % of amine fed to reclaimer

4 Containment Removed by Amine Absorber Contaminant Unit Coal (min max range) Coal Base case NGCC Base case % Removal from gas SO 3 ppmv % SO 2 ppmv % NO 2 ppmv % Other NO X ppmv % HCl ppmv % HF ppmv % Fly ash mg/nm % Hg μg/nm % Se μg/nm % Other metals μg/nm % Conservatively high

5 Thermal Reclaiming Lean solvent to exchanger 1.5 wt% HSS Purified Amine (95% recovery) Condenser Bleed to Reclaimer CO 2 to stripper Stripping Still Hot lean solvent 95% amine recovery Reboiler 154 o C/1 bar, 1 mol NaOH/ 1 mol HSS Impurities (5% Amine loss) 100% removal of HSS s and metals

6 Ion Exchange & Electrodialysis 1 mol NaOH/ 1 mol HSS Aqueous Brine to Wastewater Treatment Plant Aqueous Brine to Wastewater Treatment Plant Ion Exchange Lean Amine Reclaimer Feed CO 2 Pretreatment Particulate Filter Caustic Pretreatment Cation Exchange Resin Anion Exchange Resin Purified Amine (99% recovered) 99% amine recovery 90% removal of HSS s Sulfuric Acid for Regeneration (Distilled, deionized water) Caustic for Regeneration (Distilled, deionized water) No metals removal Electrodialysis 97% amine recovery 92% removal of HSS s No metals removal

7 mm/hr Rates of amine loss (coal) 0,5 0,45 0,4 0,35 0,3 0,25 0,2 0,15 0,1 0, C 150 C 135 C MEA PZ MDEA/PZ Thermal Ion exchange Thermal Deg Oxidation Nitrosation Volatility Reclaiming Loss 5 vol% O ppm NO 2 NGCC: 2x oxidation rate 95% amine recovery 0.1% slipstream 0.1 % drawoff 99% recovery

8 mm/hr Rates of contaminant accumulation (coal) 0,18 0,16 0,14 0,12 0,1 0,08 0,06 0,04 0,02 Not harmful to solvent DEA + 1-MPZ HEEDA, HEIA/AEP, HEP HeGly/Bicine HEI/EDA, 2-imid Formate, HEF/FPZ 0 MEA PZ MDEA/PZ Sulfate: [90% of 5 ppm SO 2 ] Nitrate: [10% of 45 ppm NO x ] Polishing scrubber to reduce SO 2 highly recommended

9 Operating Cost ($MM/yr) Economics: MEA Coal Base Case 5 4,5 4 3,5 3 2,5 2 1,5 1 0,5 Energy Mebrane/Resin Replacement Other Consumables Solvent Losses Fixed O&M 0 Thermal reclaiming Ion Exchange Electrodialysis PEC: $MM Total: $/tonne CO 2

10 Estimated Normalized Cost: Coal & NGCC, 0.1% slipstream Coal NGCC Alternative case 1.5% HSS reduces cost e.g. MDEA/Pz Thermal reclaiming, Coal:1.33$/tonneCO 2 & NGCC: 0.9$/tonneCO 2

11 % Change in Economics Sensitivity Analyses (MEA/Coal/Thermal Reclaiming) C 105 C Base Case: Stripper: 120 C 10 % 2.5 % 2x 2/3x 5.5 mol% O 2 5 ppm SO 2 45 ppm NO x +/- 2x fly ash 6 mg/nm 3 50% cap. Low metals (no ox. catalysis)

12 Waste Disposal Options ~10x cost

13 Conclusions For MEA thermal reclaiming was found to be least expensive, whereas for MDEA/Pz and Pz ion exchange and electrodialysis was found to be least expensive. [All within uncertainties of assumptions] For NGCC case Ion exchange followed by electrodialysis was found to be least expensive Solvent reclaiming will be % of total electricity cost for coal and % for NGCC case Metal and mercury content will trigger Reclaimer waste Classification as Hazardous in US, increasing disposal cost Polishing scrubber to reduce SO 2 in coal flue gas to <1 ppmv highly recommended

14 Acknowledgements IEAGHG: Prachi Singh Trimeric: Andrew Sexton, Kevin Fisher, Anne Ryan UT: Paul Nielsen, Nathan Fine, Steven Fulk, Eric Chen, Gary Rochelle URS: Katherine Dombrowski, Jean Youngerman, William Steen, Douglas Orr This presentation contains the expression of the professional opinion of Trimeric Corporation (Trimeric), URS Corporation (URS), and the University of Texas (UT) as to the matters set out herein and it was prepared pursuant to an agreement dated November 9, 2012 between Trimeric Corporation and IEA Environmental Projects Ltd. Greenhouse Gas R&D Programme (IEAGHG) and the methodologies, assumptions and procedures stated therein. This presentation is written solely for the purpose stated in the agreement, and for the sole and exclusive benefit of IEAGHG, whose remedies are limited to those set out in the agreement. This presentation is not intended for the use of anyone other than IEAGHG, and anyone other than IEAGHG who elects to use and/or rely on this agreement, does so at its own risk.

15 Waste Characterization Characterization was performed based on US and EU regulation by evaluating the characteristics of the solvent, metals content, nitrosamine content from model In US waste hazardous classification would be based on the metals content and mercury for coal-fired thermal reclaimer waste In EU thermal reclaiming waste from coal and NGCC will be hazardous Waste from ion exchange and electrodialysis 95% water; No or very low metal content Piperazine (Pz) is a sensitizing agent, so Pz and MDEA/Pz containing waste stream from ion exchange and electrodialysis may be hazardous in EU

16 Recommendations Amine Degradation Oxidative degradation rate of the amine and oxidation products are least understood phenomenon that impact impurity accumulation and reclaimer design Solvent Reclaiming Waste Disposal Options Developing methods for selective removal of metals; Atmospheric reclaiming of nonvolatiles; Development of volatiles reclaiming to minimize air emissions of ammonia, aldehydes and other volatile degradation products etc. Analysis of amine waste composition from plant, Estimation of Chemical Oxygen Demand for WWT, Evaluation of waste disposal cost, Firing in HRSG require further investigation, Effect on emission

17 Why Solvent Reclaiming? Amine solvents tend to degrade in presence of heat/o 2 and accumulate impurities from flue gas Degradation compounds increases solvent viscosity affecting mass/heat transfer, enhances corrosion and foaming, increases toxicity Solvent reclaiming removes build up impurities Reclaiming reduces solvent makeup cost and concentrates degradation products to reduce the waste disposal cost

18 Degradation products MEA Product mole produced /mole amine lost Thermal Degradation HEIA 0.2 triheia 0.05 HEEDA in equilibrium w/ HEIA MEA trimer in equilibrium w/ triheia Oxidative Degradation Ammonia 0.67 Formate/HEF 0.12 Oxalate oxylamide (HEO) Nitrate 0.01 Nitrite HEI 0.06 HeGly 0.05 HEI Amides HeGly

19 Reclaimer Assumptions Continuous slipstream ratio of 0.1% to reclaimer unit (equivalent to 1% slipstream batch mode operating 10% of plant operation time) 100% recovery of water and CO 2 1 mol NaOH added/mol HSS

20 Economic Evaluation Capital costs (PEC) Reference capital costs from thermal reclaiming vendors Reference ion exchange, electrodialysis costs from 1988 LRGCC Compared to cost estimates from Aspen In-Plant Cost Estimator 4 parallel units 0.6 scale-up factor Lang Factor = 3 8% discount rate

21 Waste Handling In Wiped Film Evaporator Thermal Reclaimer sludge removed without water addition Other thermal reclaiming 50%+ water will be added for dilution. Required to be dried/solidified prior to landfill For Cement kiln waste must be analysed, stabilized blend of waste will be used for constant composition For Co-firing at Power Plant a sludge handling system is required (dilution, pumping, storage tank etc.) Waste management plan (monitoring, testing, record keeping, reporting) and operator training will be required

22 Landfill and Waste Incineration In US Non-Hazardous (NGCC) and Hazardous (Coal) waste can be disposed in commercial landfill In EU wastes do not meet the criteria not suitable for landfill For Incineration, profile of waste is required on the energy generated and water content in US Waste Streams NGCC Power Plant Coal Power Plant Non-hazardous Waste Landfill ($/year) Hazardous Waste Disposal, Landfill/ Incinerator ($/year) MEA 208,000 2,531,000 10x 12x MEA + 50% Water 567,000 6,395,000 PZ 369,000 3,963,000 PZ + 50% Water 981,000 10,103,000

23 Cement Kiln Addition of amine sludge may require additional testing and monitoring Cement Kiln dust waste need to be evaluated for metal and chlorine content 1% Chlorine in waste will not affect overall Chlorine content 0.5-3% Ash in coal amine sludge no effect Sulfate and NaOH range <1% %; may require bypass to remove sulfate to avoid effect on clinker quality Rotary Kiln Coal case of MDEA/Pz Thermal reclaimer waste can provide up to 15% Thermal Input to rotary kiln

24 Co-firing at Power plant Prior testing is required to identify the waste characteristics Reclaimer waste co-fired using exiting oil gun/with an alternative fuel Co-firing waste is subject to regulation for commercial and industrial solid waste incinerator Co-firing at NGCC HRSG is possible with additional considerations e.g. temperature, residence time, corrosion, emission (SOx, NOx, particulates) Projected MDEA/Pz thermal reclaimer waste flow rate of kg/hr for 900MWe SCPC plant: Coal / Waste Stream Flow rate, Heat Input, kg/hr GJ/hr Base Case Coal 293,300 7,815 Undiluted Reclaimer waste

25 Effect on SCPC Emission Parameter Concentration of Constituent in Stream Mass Flow rate, kg/hr Coal, MDEA/PZ Thermal reclaimer sludge Ratio of Sludge Flow rate to Coal Flow rate Coal Undiluted Undiluted Coal Sludge Sludge Flowrate , % Moisture 9.5% 0% 27, % Sulfur 0.9% 2.6% 2, % Chloride 0.3% 1.1% % Nitrogen 1.4% 9.3% 4, % Mercury (Hg) 0.04 ppm 3.7 ppm % Selenium (Se) 0.05 ppm 4.7 ppm % Arsenic (As) 1.26 ppm 0.8 ppm % Cadmium 0.07 ppm 0.3 ppm (Cd) % Chromium 0.47 ppm 9.2 ppm (Cr) % Lead (Pb) 6.8 ppm 0.9 ppm % Fly ash 13.5% 1.2% 39, %

26 Use as SNCR/SCR Reagent 35-70% amine in sludge, possibly converted to NH 3 in SCR Could replace half of SNCR reagent (900 MW e SCPC) Consideration needed for residence time, corrosion, consistency in reclaimer waste, heavy metals, NO x

27 Waste Water Treatment Plant Ion exchange and Electrodialysis amine waste is more suitable to be treated in WWT In US currently there is no specific regulations for amine sludge In EU reclaimer waste is subject to additional regulations Additional onsite waste water treatment system (Advanced oxidative / Denitrification system) is required to treat waste containing MEA, MDEA and Pz Cost of different waste water treatment will be dependent on waste characteristics

28 Sensitivity Analysis MEA Thermal Reclaiming, Parameters Overall HSS Conc. (wt%) $/ton CO 2 % Change in Economics from Base Case Base Case % 105 C Regeneration Temp % 135 C Regeneration Temp % 10% Inlet O % 2.5% Inlet O % 90 ppm NO X (3 ppm NO 2 ) % 30 ppm NO X (1 ppm NO 2 ) % 10 mg/nm 3 fly ash (6mg/Nm 3 ) % 3 mg/nm 3 fly ash % 0 ppm corrosion metals (100 ppmv dissolved iron) %

29 Electrodialysis 97% amine recovery 92% removal of HSS s No metals removal