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NITRIC ACID PLANT (63% wt. HNO 3 ) Ammonia-Based Fertilizers

NITRIC ACID PLANT (63% wt. HNO 3 ) Ammonia-Based Fertilizers. University of Illinois at Chicago Department of Chemical Engineering CHE 397 Senior Design II January 24, 2012 Thomas Calabrese (Team Leader) Cory Listner Hakan Somuncu (Scribe) David Sonna Kelly Zenger. Today’s Agenda.

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NITRIC ACID PLANT (63% wt. HNO 3 ) Ammonia-Based Fertilizers

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  1. NITRIC ACID PLANT (63% wt. HNO3)Ammonia-Based Fertilizers University of Illinois at Chicago Department of Chemical Engineering CHE 397 Senior Design II January 24, 2012 Thomas Calabrese (Team Leader) Cory Listner Hakan Somuncu (Scribe) David Sonna Kelly Zenger

  2. Today’s Agenda • Big Picture – Fertilizer Plant • Supplier • Customers • Nitric Acid Plant Design Basis • Starting Reagents • Products • Environmental Concerns • Process Block Flow Diagram • General Process Overview • Catalysts • Useful Energy Recovery • Pressure and Temperature Effects • NOx Emission Control

  3. BIG PICTURE-FERTILIZER PLANT Ammonia (Liquid) Supplier (603.5 TPD) INTERNAL CUSTOMER AIR (10820 TPD) 2571.2 TPD HNO3 (63 wt%) OUTSIDE CUSTOMERS 717.8 TPD HNO3 (63 wt%)

  4. Design Basis • Produce 3,289 TPD of 63% wt. nitric acid solution (~14M) • Starting Reagents • Ammonia (NH3) - 603.5 TPD • Excess Air – 10,819.5 TPD • Excess Oxygen (O2) from Air – 2,272.0 TPD • Products • 63% wt. Nitric Acid Solution (HNO3) - 3,289.0 TPD • Water (H2O) – 1,216.9 TPD • Useful Heat • Environmental Concerns • Oxides of Nitrogen (NOx) (<200 ppm) • Nitrous Oxide (N2O) (<200 ppm)

  5. Catalytic Reactor (Oxidation of NH3) Ammonia Filtration Mixing 572 TPD NH3 (g)from Ammonia Plant NO (g) 1,843 TPDSteamto CHP Air Filtration Air Compression Heat Recovery (Oxidation of NO) 10,322 TPD Air Atmosphere Gas Expander Hot Tail Gas NO2 (g) Absorption Column (Formation of HNO3) Bleacher Column (Strip Dissolved NOx) Nox Compressor NOx (g) 607 TPD Process Water Cold Tail Gas 3,289 TPD 63% wt. HNO3 718 TPD to Market 2,571 TPD to Ammonium Nitrate

  6. General Process Overview • Primary Chemical Reactions (Ostwald Process) • Oxidation of Ammonia to Nitrogen Monoxide4NH3 (g) + 5O2 (g)  4NO (g) + 6H2O (g) • Oxidation of Nitric Oxide to Nitrogen Dioxide2NO(g) + O2 (g)  2NO2 (g) • Reaction of Nitrogen Dioxide to Nitric Acid3NO2 (g) + H2O (l)  2HNO3 (aq) + NO (g) • Side Chemical Reactions • Simultaneous to Oxidation of Ammonia 4NH3 (g) + 3O2 (g)  2N2 (g) + 6H2O (g) 4NH3 (g) + 4O2 (g)  2N2O (g) + 6H2O (g)

  7. Materials of Construction

  8. Energy Recovery Methods • Heat from Oxidation in Catalytic Reactor • Heat from Absorption • Mechanical Energy from Tail Gas Expansion

  9. Energy Recovery Methods • Net Energy Exporter • Oxidation reaction: 1,600 Btu/lb of pure nitric acid • Absorption process: 370 Btu/lb • Tail gas turbine: 325 Btu/lb (~80% of mechanical energy used) • Total: 1,955 Btu/lb (967-1,217 Btu/lb at 50-65% efficiency) • Little effect from single/dual-pressure and other considerations • Steam (standard) • Augmented with natural gas at startup • Combined Heat & Power (CHP) • Generate high pressure steam and run through turbine • Offsets power purchase from the grid

  10. Which Catalyst?

  11. Why are Pressure and Temperature Important?

  12. Controlling NOx Release • Primary Methods-reduce N2O formed during ammonia oxidation • 70-85% efficiency • Add an “empty” reaction chamber between the catalyst bed and the first heat exchanger (increase residence time) • Modify the catalyst used during the ammonia oxidation • Secondary Methods-reduce N2O formed immediately after ammonia oxidation (Selective Catalytic Reduction) • Up to 90% efficiency • Secondary catalyst is used to promote N2O decomposition by increasing the residence time in the ammonia burner • 2N2O (g)  2N2 (g) + O2 (g)

  13. Controlling NOx Release • Tertiary Methods-reduce N2O from or to the tail gas (Non-Selective Catalytic Reduction) • 80-98+% efficiency • A reagent fuel (e.g. H2 from an ammonia plant purge) is used over a catalyst to produce N2 and water • Alternatively, following SCR the tail gas is mixed with ammonia and reacts over a second catalyst bed to give N2 and water

  14. Thermodynamic Models for HNO3 (63 wt%) Plant • Up-stream of HNO3 (63 wt%) Plant – Soave-Redlich-Kwong (SRK) • The SRK property method uses the Soave-Redlich-Kwong (SRK) cubic equation of state for all thermodynamic properties with option to improve liquid molar volume • Mixture Types • Use the SRK property method for non-polar or mildly polar mixtures. • This property method is particularly suitable in the high temperature and high pressure regions • Range • It can be expected reasonable results at all temperatures and pressures. • The SRK property method is consistent in the critical region. • Therefore, unlike the activity coefficient property methods, it does not exhibit anomalous behavior. Results are least accurate in the region near the mixture critical point. • Down-stream of HNO3 (63 wt%) Plant - ELECNRTL • It can handle very low and very high concentrations • It can handle aqueous and mixed solvent systems • The solubility of supercritical gases can be modeled using Henry ‘s Law • The Redlich-Kwong equation of state is used for all vapor phase properties • Mixture Types • Any liquid electrolyte solution unless there is association in the vapor phase • Range • Vapor phase properties are described accurately up to medium pressures. Aspen Database

  15. Summary • Produce 3,289 TPD of 63% wt. Nitric Acid • Key Equipment • Ammonia Evaporator, Air Compressor, Catalytic Reactor, and Absorption Column • Competing Processes • Platinum-Rhodium Alloy or Cobalt Oxide • Single or Dual Pressure System • Energy Recovery • Materials of Construction

  16. Looking Ahead • Problem areas to be addressed • Catalyst decision • Single or dual pressure plant decision • Material balance • Thermodynamic model • Method of pollution control • Equipment material • Finalized Material and Energy Balances • Rough Economics • Hand Calculations • Additions to Report

  17. References • ASPEN Thermodynamic Database. • Available and Emerging Technologies for Reducing Greenhouse Gas Emissions from the Nitric Acid Production Industry. U.S. Environmental Protection Agency. 2010. <http://www.epa.gov/nsr/ghgdocs/nitricacid.pdf>. • Bell, B. Platinum Catalysts in Ammonia Oxidation. Platinum Metals Rev. 4. 1960. • Best Available Techniques for Pollution Prevention and Control in the European Fertilizer Industry, Production of Nitric Acid. EFMA. 2000. <http://www.efma.org/PRODUCT-STEWARDSHIP- PROGRAM-10/images/EFMABATNIT.pdf>. • Cobalt Oxide Catalyst. Catalyst Development Corporation. 2003. <http://www.cobaltoxide.com/>. • Pratt, Christopher, and Robert Noyes. Nitrogen Fertilizer Chemical Processes. Pearl River: 1965. • Ullman’s Encyclopedia of Industrial Chemistry. Volume A17. VCH.

  18. Questions?

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