NeuStream -DR: Improving the effectiveness of DSI while substantially reducing the chemical cost

Transcription

1 NeuStream -DR: Improving the effectiveness of DSI while substantially reducing the chemical cost J.P. Feve, V.P. Business Development, Do Not Distribute w/o NSG Permission

2 Stack Current DSI Systems Flue gas w/ sulfur dioxide Particulate collection Flue gas w/o sulfur dioxide Boiler Truck or railcar fill Sorbent Sorbent Supply injection DSI system DSI Reject Solids (fly-ash, Na 2 CO 3, Na 2 SO 4 ) Dry sorbent injection (DSI) is a low CapEx (< 20% compared to wet scrubber), high OpEx, alternative desulfurization/acid gas system Most current DSI installed for MATS compliance: Target high acid gas removal, but low (~<50%) SO 2 removal Sorbent injection: Lime, Trona, SBC (in furnace or upstream of air pre-heater) Mostly installed on units burning low-sulfur coal 2

3 Challenges With Current DSI Systems High operating cost (up to 2/3 s of injected sorbent is un-reacted) SO 2 removal too low for higher-sulfur coal. Achieving >90% removal no feasible with calcium and too costly with sodium Calcium sorbent decreases performance of ESP (resistivity) Impact of large flows of sorbent on ESP and baghouse when used for higher sulfur removal Leachability of heavy metals (As, Se) in post-dsi fly ash with sodium sorbent 3

4 Stack NeuStream -DR Process Flue gas w/ sulfur dioxide Particulate collection Flue gas w/o sulfur dioxide Boiler Truck or railcar fill Sorbent Supply Sorbent injection DSI system Recycled sorbent (NaHCO 3 ) DSI Reject Solids (fly-ash, Na 2 CO 3, Na 2 SO 4 ) Flue gas NeuStream -DR process Fly-ash (low sodium) Chemical supply (lime, water, NaCl) Solid Byproducts (CaCO 3, Na 2 SO 4 ) 4

5 NeuStream -DR: Post DSI Fly Ash Recycling for Sorbent Recovery NeuStream -DR enables an equivalent performance and much lower system cost alternative to wet/dry FGDs (low to moderate sulfur coals) NeuStream -DR enables economical use of trona as a higher performance, more reliable alternative to limestone/lime DSI NeuStream -DR recovers and recycles wasted sorbent and decreases DSI sorbent cost by 60%-80% Recover over 90% of un-reacted trona and convert to 100% sodium bicarbonate Secondary (optional) process recovers reacted trona (sodium sulfate) NeuStream -DR provides greater design flexibility for DSI systems: Higher SO 2 removal (or ability to burn higher sulfur coal) by injecting more trona at lower cost Injection on cold side of pre-heater to increase reliability without sacrificing removal efficiency 5

6 SO 2 removal NeuStream -DR Cost Comparison: 250MW Coal Plant, Bituminous Coal Sorbent cost saving (M $/year) 100% 18 Bituminous coal, 250MW plant, 1.05 lbso 2 /MMBTU Bituminous coal, 250MW, 1.05 lbso 2 /MMBTU 90% 16 80% 14 70% 60% 50% 40% 30% 20% 10% 0% recycling Na2CO3, ESP recycling Na2SO4, ESP no recycling, ESP no recycling, BH Trona injected (ton/hr) DSI-R vs ESP BH vs ESP SO 2 removal (%) Lower NSR required for BH vs ESP: significant savings on sorbent costs at high removal NeuStream -DR has 2 advantages: recycles unused sorbent and generates SBC (lower NSR to achieve same removal) maximum savings, at lower CapEx, shorter construction time, and lower parasitic power 6

7 NeuStream -DR Cost Comparison: 250MW Coal Plant, PRB Coal Annualized Cost ($/MW hr) $30 $25 90% SO 2 removal 0.69 lb SO 2 / MMBTU $20 $15 $10 Pay-back 1.5 year $5 $ Remaining Useful Life of Plant (Years) Source: 2010 IPM cost models, Sargent and Lundy for EPA Conventional Wet FGD Conventional Dry FGD Dry Sorbent Injection NeuStream-S NeuStream-DR 7

8 NeuStream -DR: Potential OpEx Savings Typical NSR for 90% SO 2 removal with baghouse: 3.3 (unmilled Trona) (milled Trona) For 90% SO 2 removal, Na 2 :SO 2 unreacted Reference: IPM Model Revisions to Cost and Performance for APC Technologies: Dry Sorbent Injection Cost Development Methodology, Sargent and Lundy, Typical 250MW plant: 10,000 BTU/kw-hr, 0.69 lb SO 2 / MMBTU, NSR = 3.26 ton trona /hr $/hr $/yr* $ / ton SO 2 Total Trona Injection 6.6 $1,191 $8,349,885 $1,535 Unreacted Trona 4.8 $862 $6,044,702 $1,112 *80% capacity factor Potential Savings 95% Recovery of Unreacted Trona Trona Savings $6,045,000 Lime Costs $805,000 Total Savings $5,240,000 (63%) 8

9 NeuStream -DR Process Flow 18 Fly Ash Na 2 SO 4 Na 2 CO3 1 Water 2 FR01 (filtration) NaCl T02 Sparging tank Exhaust (to stack) FR02 (filtration) Lime FR03 (filtration) T01 FA Mixing tank 3 P01 Pump 4 5 Fly Ash CaCO 3 TO2 Sparge Tank CO 2 or flue gas 7 10 P02 Pump NaHCO 3 T03 Lime addition tank 15 P03 Pump CaCO 3 NeuStream -DR system: Reduces sodium concentration, and hence leachability, of post-dsi fly ash similar to pre-dsi fly ash Process independent of DSI injection and power generation process Simple, reliable design, no exotic chemicals 9

10 NeuStream -DR Pilot Results Lab Results Batch Process Pilot Results Property 3 step 3 step w/ wash 3 step 3 step w/ wash Purity 88% 90% 79% ± 1.4% On-going Yield 82% 98% 76% ± 3.7% On-going Powder low properties of recycled solids are very close to post-dsi fly ash mix (easy flow, slightly better than trona) Toxicity characteristic leaching procedure per SW C mg/l Raw Post DSI solids, Post fly ash unprocessed NeuStream -DR Chromium Selenium Arsenic ND

11 Summary NeuStream -DR process offers major advantages: Up to 80% decrease in DSI OpEx with optional NaSO 4 converter Removes most of the soluble sodium from fly ash Low power usage and water consumption Small footprint, simple operation Gives utilities added flexibility: Install DSI now due to MATS Regulations Add NeuStream -DR later for cost control, greater SO X control, cleaner fly ash 11

12 NSG Contact Information Eric Klein, CTO, J.P. Feve, V.P. Business Development,