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Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Fuel Lean Gas Reburn in Mineral.

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Presentation on theme: "Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Fuel Lean Gas Reburn in Mineral."— Presentation transcript:

1 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Fuel Lean Gas Reburn in Mineral Processing Kilns Dung (Edward) Le Cadence Environmental Energy Eric Hansen The Eric Hansen Group Introduction – Ted T Reese Cadence Environmental Energy

2 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level NO x Formation Mechanisms Most NO x created by either Thermal or Fuel NO x Thermal NO x N 2 (air) + O 2  NO x Fuel NO x N(fuel) + O 2  NO x

3 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level NO x Reduction Techniques Process Control Reduce excess air and flame temperature Process Technologies Staged combustion Reburn air injection Low NO x burner SNCR Fuel-Lean Gas Reburn Technology

4 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Fuel Lean Reburn Chemistry Fuel-Lean Reburn is the method to inject hydrocarbon fuels in the oxidizing zone at the back-end of the kiln NO x reacts with hydrocarbon radicals to form reduced nitrogen species These nitrogen species react with additional NO x to form nitrogen gas

5 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Mechanical Schematic – FLR Fuel-lean reburn =.CH x + Other Species.CH x + NO x =.CN +.NH 2 + H 2 O

6 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Post Combustion Methods for NO x Reduction Fuel lean reburning can be used to compete with the post- combustion NO x control technologies such as SNCR Cement Industry prefers SNCR as post-combustion NO x control method – WHY? SNCR & Fuel Lean Reburn - Goals Generate NO x reducing species from decomposition of fuel Achieve NO x reductions in most economical form SNCR uses ammonia based reagents Fuel Lean Reburn uses oil based reagents

7 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level SNCR Selective Non-Catalytic Reduction (SNCR) Most common reagents are aqueous ammonia and UREA Reagents are injected at specific temperature zones Targeted temperatures zone between 870C – 1100C NO x reduced to nitrogen gas and water 4NH 3 + 4NO + O 2 4N 2 + 6H 2 O 4NH 3 + 2NO 2 + O 2 3N 2 + 6H 2 O

8 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level SNCR Efficiency Dependent upon many factors Temperature Molar ratio of NH 3 :NO x One concern of using SNCR is the ammonia slip level Slip occurs when unused ammonia is released at the flue stack which may potentially create a visible plum stack Significant environmental concern to the community

9 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level SNCR Costs Plants considering SNCR usage require new storage for reagent SNCR involves heavy capital expenditures New storage equipment required New permitting required Annual reagent costs Costs only value is reduced NO x No other combustion benefit with ammonia use Unlike SNCR - fuel lean reburn technology may require a much lower capital expenses and very competitive reagent cost.

10 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Fuel Lean Reburn Comparison Cost of a pure NH 3 is approximately $1000 US/ton Cost of fuel lean reburn reagent such as oil or natural gas is less Fuel Lean Reburn expected to require lower annual reagent costs and minimum additional storage cost 1 ton of ammonia = $ ton of oil = $790 1 ton of natural gas = $168

11 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Fuel Lean Reburn Advantages Using a hydrocarbon based reagent natural gas or oil Most cement plants already use the hydrocarbon based reagents to preheat the kilns during start-up A simple connection to supply the hydrocarbon based reagents at the back end of the kiln Lean Fuel Reburn can be done at limited amount of cost to achieve similar NO x reduction as using SNCR

12 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Fuel Lean Reburn Possibilities Fuel Lean Reburn technology is primarily used in the power industry Cement Industry uses the technology but minimal use SNCR technology has been more popular compared to FLR SNCR poses challenges High Capital costs High annual operating costs Expectation of increased reagent cost (high future demand) Slip possible with SNCR use - visible stack emission With documented SNCR costs and challenges, Fuel Lean Reburn method may pose an advantage over the more common SNCR method

13 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Challenge to Industry Perhaps the cement industry should re-examine the possibility of using fuel lean reburn method as a post-combustion NO x reduction before committing to a very expensive SNCR method Why do cement plants seem to not have a problem with spending millions of dollars to utilize SNCR prior to trying fuel lean reburn?

14 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Stratified Gasses Kiln gasses are stratified at a high degree The top of the kiln contains high O 2 and high temperature gasses travelling at high velocity The bottom of the kiln contains CO 2, hot meals with much lower temperature These gas layers never have the opportunity to mix Getting these gas layers mixed is the key to fuel-lean reburn (Increased performance by eliminating kiln gas stratification)

15 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Mixing Technology

16 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Need for Improved Mixing Better cross-sectional mixing in the kiln will allow fuel-lean reburn to mix effectively in the reburn zone for optimum NO x reduction Imagine highly stratified kiln gasses coming in contact with the atomized fuel-lean oil reburn. It would be very difficult to achieve well-distributed hydrocarbon radicals in the stratified gas stream to reduce NO x effectively. With additional mixing, hydrocarbon radicals from fuel-lean reburn will have a better chance in contact with NO x This mechanism may vastly improve the ability to reduce NO x using fuel-lean reburn technology

17 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level MIXING TECHNOLOGY

18 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Conclusion In general, fuel lean reburn method may be used as an alternative solution for the post-combustion NO x. At present, SNCR is widely considered the chosen post combustion method for NO x reduction but it comes with large capital investment and ongoing reagent costs. The fuel lean reburn method may still not widely adopted as a method of NO x reduction in cement industry, but it appears to deserve a reexamination because it may significantly reduce the customer’s capital and reagent costs while achieving the same or better NO x reduction efficiency than SNCR.

19 Click to edit Master title style Click to edit Master text styles –Second level Third level –Fourth level »Fifth level Fuel Lean Gas Reburn in Mineral Processing Kilns Dung (Edward) Le Cadence Environmental Energy Eric Hansen The Eric Hansen Group Introduction – Ted T Reese Cadence Environmental Energy


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