Combustion science technology

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Published Date:19-07-2017
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New Developments in Combustion Technology Geo. A. Richards, Ph.D. National Energy Technology Laboratory U. S. Department of Energy 2014 Princeton-CEFRC Summer School On Combustion Course Length: 6 hrs June 23-24, 2014 Energy - Everyday, Everywhere Healthcare, education, infrastructure, water, transportation, communication, agriculture, recreation……… ‹› Energy - Everyday, Everywhere…. ….Except…… From the International Energy Agency Web-site: “….Based on this updated analysis, we estimate that in 2009 the number of people without access to electricity was 1.3 billion or almost 20% of the world’s population…..” ydevelopment/accesstoelectricity/ ‹› Electricity Demand 2011 Electricity Demand 2035 4,084 BkWh / Year 4,979 BkWh / Year 68% Fossil Energy 68% Fossil Energy Coal Coal + 22% 34% Oil 42% Gas 1% Gas United States Oil 25% 34% 1% Nuclear Nuclear Renewables 19% 16% 16% Renewables 13% 2,171 mmt CO 2,247 mmt CO 2 2 22,113 BkWhr / Year 39,854 BkWh / Year 68% Fossil Energy 65% Fossil Energy Gas + 80% Gas Coal Coal 22% 23% 41% 40% World Nuclear Nuclear 12% 10% Oil Oil 5% 2% Renewables Renewables 25% 20% ‹› 12,954 mmt CO 19,122 mmt CO 2 2 Sources: U.S. data from EIA, Annual Energy Outlook 2014 ‘er; World data from IEA, World Energy Outlook 2013, slide courtesy Peter Balash, NETL Why not my way? Coal Wind Hydro Gas Nuclear Solar “It’s all regional. It’s all local. And we just have to descend to that level to judge it.” – Vaclav Smil, discussing preferable energy resources, Wall Street Journal, Wed April 9, 2014, pp. R-1, Business and Environment special section. ‹› Why not my way? One size does not fit all ‹› Energy and Carbon Dioxide • Carbon dioxide capture and storage – costly, but not explicitly required. • Carbon dioxide utilization in enhanced oil recovery (EOR) is needed, now. • Carbon dioxide costs from natural source anthropogenic sources. Delivered CO2 prices today 10-40/tonne Domestic EOR CO Use 2 CO supply for North America EOR 2 million tonne/yr Can we develop efficient & affordable methods to supply CO ? 2 A typical 550 MW coal plant emits 3.5 million tonne/ year Graphics and information NETL. Reference: DiPietro, J. P., Next generation Enhanced Oil Recovery, Presented at CO2; the Carbon Dioxide Utilization Congress, San Diego, California, Feb. 19, 2014. spx?Action=View&PubId=348 Available at 5ada3b04984f ‹› Greenhouse Gas New Source Performance Standard (Proposed standard for new sources; comments accepted to May 9, 2014. Differs from proposed emission standards for existing sources, released June 2, 2014, 2,500 Existing Subcritical PC 2,000 New 1,500 SC PC NSPS Limit 1,000 New Uncontrolled New 500 NGCC Supercritical PC New 90% CCS NGCC 90% CCS 0 ‹› “Cost and Performance Baseline for Fossil Energy Plants, Volume 1: Bituminous Coal and Natural Gas to Electricity”, Revision 2a, September 2013, Lb CO /MWh 2Cost of CO Capture, /ton CO 2 2 140 123/ton CO 2 120 105/ton CO 2 32 100 27 80 21 First of a kind 18 60 Next of a kind (high range) Next of a kind (low range) 40 70 60 20 0 Subcritical PC New Supercritical, Retrofit, 90% CCS 1,100 Lb CO2/MWh “Cost and Performance Baseline for Fossil Energy Plants, Volume 1: Bituminous Coal and Natural Gas to Electricity”, Revision 2a, September 2013 /ton CO 2 Carbon dioxide capture options • Existing options: costly (1) Add a flue gas CO 2 • Next generation options: scrubber (e.g. photo below). depend on thermal (2) Convert hydrocarbons to science research: hydrogen and CO /w 2 – Supercritical carbon dioxide separation/capture. power cycles: 300 bar combustion? (3) Separate oxygen from air – Pressurized oxy-fuel. and use oxy-fuel – Chemical looping combustion. combustion. – Pressure-gain combustion for efficiency. – “Direct Power Extraction” via MHD 240 MWe slipstream at NRG Energy’s W.A. Parish power plant – Note the size of CCS process area. Photo courtesy Mike Knaggs, NETL ‹› The role of capture AND generator efficiency • A simple Define: heat/energy a = (kg CO produced) / (kg fuel burned ) 2 balance defines w = (separation work, Joules ) / (kg CO ) CO2 2 CO 2 the overall efficiency h with ov a carbon separation unit. h g Generator Efficiency • Reducing the Q = m DH f W 1 W Fuel Heat o Net penalty from Gross Input Generator Output Generator Carbon carbon capture Work Separation comes from Unit BOTH: – Decreasing w CO2 – Increasing h g Approx Ranges: (30 – 60%) (6-10%) ‹› This presentation Updated, expanded from 2012 CEFRC lecture: – Inherent carbon capture: chemical looping combustion (Day 1) – Step-change in generator efficiency: pressure gain combustion (Day 2) – Frontier approach (?): making oxy-fuel an efficiency advantage (Day 2) Sampling & Diagnostics RDC Flow P-gain rig NETL ‹› Disclaimer This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. ‹› Chemical Looping Combustion ‹› Oxy-fuel background Oxy- fuel achieves carbon capture very easily: Air-Combustion: CH + 5/4(O + 3.8N )  CO + 1/2H O +4.7 N 2 2 2 2 2 Costly to extract the CO from the N with amines 2 2 Oxy-Combustion: CH + 5/4(O )  CO + 1/2H O 2 2 2 Easy to extract the CO from the H O via condensation 2 2 “Usual” oxy-fuel approach: oxygen diluted with CO or H O added to an existing boiler cycle. 2 2 – Dilution used to keep the temperatures same as Meridosia Illinois – Future Gen 2.0 planned site existing cycle. – Efficiency of the plant is penalized by the energy needed to make oxygen. Significant oxy-fuel demonstration projects are occurring around the world. – See for example: working-group/demonstrations.html – More than 14 demos 10MWth listed Courtesy University of Utah – oxyfuel burner tests ‹› Making oxygen for oxy-fuel • Oxygen can be supplied today by commercial Air Separation Units (ASU) based on established cryogenic separation. • The energy needed to separate oxygen from air is significant (see below). • In conventional oxy-combustion, we dilute the purified oxygen to maintain the same boiler flame temperature as in air-combustion. 1 mole of air 0.21 moles oxygen Dilute again Air p = 1 atm with CO or steam O2 2 0.21 moles oxygen p O2 Separation = 0.21 atm Unit 0.79 moles nitrogen p (ASU) N2 0.79 moles nitrogen = 1 atm p = 0.79 atm N2 C + O  CO 2 2 DH DG = 394 kJ/gmol (C or O 2) Reversible separation work: 6 kJ/gmol O produced In efficient powerplants we convert 2 less than ½ of DH to work. Thus200kJ/gmol O2 work produced Current actual process: 18kJ/gmol O produced 2 Roughly 1/10 of that is needed for ASU. e.g, the change in gibbs energy for ideal mixing (Sandler, Chemical Engineering Thermodynamics (1989) pp. 313. See Trainier et al., “Air Separation Unit…..” Clearwater Coal Conference, 2010. ‹› Chemical Looping • Shares advantages of oxy-fuel – Product is just CO and H O 2 2 • No separate oxygen production is needed • Schemes for H production, carbon capture… 2 Avoiding confusion N + O 2 2 with nomenclature: (vitiated air) Today’s Refer only to the CO + H O 2 2 discussion: CO + H O FUEL REACTOR 2 2 Focus on AIR REACTOR Seal air reactor Ash Here’s why it can otherwise be confusing: the air reactor “burns” or oxidizes the metal. Recycle Fuel CO + H O 2 2 The fuel reactor “reduces” the metal oxide but Seal oxidizes the fuel. Air Thus, you could call the fuel reactor an oxidizer for the fuel OR a reducer for the metal oxide. Carbon + metal oxide = CO + metal 2 Metal + air (oxygen) = metal oxide ‹› Not quite new • Chemical looping has been around – but for different CO 2 reasons and applications. – 1954 patent to manufacture CO 2 • Similar process: iron-steam HX route to hydrogen (circa 1920) M Reduce iron with fuel and oxidize it with steam: MO 2 Air Reactor M + (O + 3.8N ) F O + 4 CO  3Fe +4 CO 2 2 3 4 2 MO + 3.8 N 2 2 3 Fe + 4 H O  Fe O + 4H 2 3 4 2 Fuel Reactor MO + C  2 CO + M 2 • And, before that….respiration. “Production of Pure Carbon Dioxide” US Patent 2,665,972 (1954) Notice the heat exchangers (HX) in BOTH fuel and air reactors. Hemoglobin “loops” Should have made it a boiler? to carry oxygen from lungs for hydrocarbon Hurst, S. (1939). “Production of Hydrogen by the Iron-Steam Method”, oxidation in cells. Journal of the American Oil Chemist’s Society, 16 (2), pp. 29-36. ‹› Basic Thermodynamics In CL combustion, the overall reaction (1) of fuel with oxygen is split into two steps (2&3) , which add to the overall. Consider an example of carbon and a metal/metal oxide (M/MO): 1) C + O  CO DH Overall fuel oxidation - exothermic DH = DH + DH 2 2 1 1 2 3 _______________________________________________________ 2) C+ MO  CO + M DH Metal oxide reduction & Fuel reactor 2 2 2 fuel oxidation – can be endothermic OR exothermic Air Reactor 3) M + O  MO DH Metal oxidation - exothermic 2 2 3 Nomenclature used in this talk: Exothermic carriers Endothermic carriers Neutral carriers DH 0, DH 0 DH 0 2 2 2 Fuel reactor Fuel reactor Fuel reactor does not consume or releases heat consumes heat release heat ‹› Chemical Looping Heat Release Air reactor: always exothermic; it releases heat. N + O 2 2 (vitiated air) Exothermic carriers: some heat will also come out in the fuel reactor CO + H O 2 2 CO + H O 2 2 Endothermic carriers: fuel reactor needs heat to reduce the metal. Seal • If you don’t put heat into the fuel reactor, the temperature will drop as reaction (2) proceeds, and the reactions will stop. Ash • You add the heat by carrying it with the oxygen Recycle carrier. Thus, the temperature of the carrier drops Fuel CO + H O 2 2 some DT from inlet to exit of the fuel reactor. Seal • The heat flow rate is then (mass flow) x (C DT ) and p (3) (2) must balance the heat used by reaction (2) • Note that steam pipes won’t work to transfer heat into Air the fuel reactor (800C input, typically - exceeds steam piping temperature limits). 1) C + O  CO DH Overall fuel oxidation - exothermic 2 2 1 _______________________________________________________ (2) C+ MO  CO + M DH Metal oxide reduction & fuel oxidation – 2 2 2 can be endothermic OR exothermic (3) M + O  MO DH Metal oxidation - exothermic 2 2 3 ‹›

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