Northshore Process Boilers BART Analysis

NOx Control

Available and Applicable Review

Reference(s) 

Reference No.

1

NOx Pollution Control 

Technology Available? Applicable?

MPCA Taconite 

BART Report

AWMA Journal 

9/05

Other

2

Comments Basic Principle

Combustion Controls

1 Overfire Air (OFA) Yes Yes x x Combustion air is separated into primary and secon

complete burnout and to encourage the formation o

2 External Flue Gas Recirculation (EFGR) Yes Yes x x Mixes flue gas with combustion air which reduces o

reduces flame temperature

3 Low-NOx Burners Yes Yes x x x Burners are designed to reduce NOx formation thro

flame temperature, and/or residence time

4 Induced Flue Gas Recirculation Burners Yes Yes x x x Need to be upfired. Need convective loop to get gas recirculated Draws flue gas to dilute the fuel in order to reduce t

5 Low Excess Air Yes Yes x Reduces production Reduces oxygen content in flue gas and reduces fla6 Burners out of Service (BOOS) Yes No x Need capacity of all burners for worst case scenario Shut off the fuel flow from one burner or more to cr

zones

7 Fuel Biasing Yes No x Combustion is staged by diverting fuel from the upp

ones or from the center to the side burners to create 

8 Reburning Yes Yes x x

Part of the total fuel heat input is injected into the fuprimary (main burners) flames to create a reducing where hydrocarbon radicals react with NOx to prod

9 Load Reduction Yes Yes x This is a strategy to reduce load on a power plant by 

demand throught efficiency projects.

10 Energy Efficiency Projects Yes Yes x decrease amount of fuel required to make an accept

11 Coal Drying Yes Yes x Requires available excess heat. Dry coal will increase the as-burned BTU value, an

to be burned. Specific energy efficiency project

14 Combustion Zone Cooling Yes Yes x x Could reduce load capabilities Cooling of the primary flame zone by heat transfer 

Y:\23\38\131\NMC Process Boilers List of Control Technologies 2006-07-11.xls 
Reference(s) 

Reference No.

1

NOx Pollution Control 

Technology Available? Applicable?

MPCA Taconite 

BART Report

AWMA Journal 

9/05

Other

2

Comments Basic Principle

15 Alternate Fuels Yes Yes x x

Requires case by case analysis. Typically, facilities experience lower NOx when burning solid fuels.

Lower combustion temps with solid fuels vs gas. Musing a fuel with less nitrogen.

16 Oxygen Enhanced Combustion No No x x Research level A small fraction of the combustion air is replaced w

17 Preheat Combustion No No x x Research level

Pulverized coal preheated and volatiles and fuel-boureleased in a controlled reducing atmosphere where reduced to N2.

18 ROFA-ROTAMIX Yes Yes x x

Combination of OFA and SCR. Wall-fired or tangeutilizes high velocity overfire air. Additional NOx rammonia injection (Rotamix)

19 NOx CEMS Yes Yes x Optimization of combustion

20 Parametric Monitoring Yes Yes x Optimization of combustion

38 Catalyst Injection (EPS Technologies) No No x Research Level A combustion catalyst is directly injected into the a

to the combustion site, initiating chemical reactions the flame.

Post Combustion Controls

21 Non-Selective Catalytic Reduction (NSCR) Yes No x x For clean services. Too much stuff in flue gas would poison catalyst Under near stoichiometric conditions, in the presen

reduced by CO, resulting in nitrogen (N2) and carbo

22 Low Temperature Oxidation (LTO) - Tri-NOx® Yes Yes x x Requires ozone generation Utilizes an oxidizing agent such as ozone to oxidize 

NOx

23 Low Temperature Oxidation (LTO) - LoTOx Yes Yes x x x

Has been included as an "applicable and available" 

technology in recent BACT analyses from multiple facilities.

Utilizes an oxidizing agent such as ozone to oxidize NOx

Y:\23\38\131\NMC Process Boilers List of Control Technologies 2006-07-11.xls 
Reference(s) 

Reference No.

1

NOx Pollution Control 

Technology Available? Applicable?

MPCA Taconite 

BART Report

AWMA Journal 

9/05

Other

2

Comments Basic Principle

24 Selective Catalytic Reduction (SCR) Yes Yes x x x

Need to inject at appropriate temperature. Applicable on clean side only.

Ammonia (NH3) is injected into the flue gas stream 

to convert NOx into N2 and water

25 Regenerative SCR Yes Yes x Clean side only

26 Selective Non-Catalytic Reduction (SNCR) Yes Yes x x x Urea or ammonia-based chemicals are injected into 

NO to molecular nitrogen, N2, and water

27 Adsorption No No x Still in research stages. Use of char (activated carbon) to adsorb oxides of n

28 Absorption Yes Yes x Similar to TriNOx Use of water, hydroxide and carbonate solutions, su

molten alkali carbonates, or hydroxides to absorb o

29 Oxidizer Yes Yes x Redundant to regenerative SCR Gas stream is sent through the regenerative, recuper

oxidizer where pollutants are heated to a combustio

30 SNOX No No x x Early commercial development stage

Catalytic reduction of NOx in the presence of amm

catalytic oxidation of SO2 to SO3. The exit gas from 

through a novel glass-tube condenser in which the S

vapor and then condensed to a concentrated liquid s

31 SOx-NOx-Rox-Box No No x Technology has not been demonstrated Dry sorbent injection upstream of the baghouse for 

injection upstream of a zeolitic selective catalytic reincorporated in the baghouse to reduce NOx emissi

32 Electron (E-Beam) Process No No x x No operating commercial applications on coal Electron beam irradiation in the presence of ammon

conversion of sulfur and nitrogen oxides into compcollected by conventional methods such as an ESP 

33 Electrocatalytic Oxidation No No x

Similar to cold plasma. Will keep watch for availability of this technology

Utilizes a reactor in which SO2, NOx, and mercury 

dioxide (NO2), sulfuric acid, and mercuric oxide res

plasma.On recent project, the vender was doing final trials 

Y:\23\38\131\NMC Process Boilers List of Control Technologies 2006-07-11.xls 
Reference(s) 

Reference No.

1

NOx Pollution Control 

Technology Available? Applicable?

MPCA Taconite 

BART Report

AWMA Journal 

9/05

Other

2

Comments Basic Principle

34 NOXSO No No x

Commercial version of adsorption. Limited experience (proof-ofconcept tests).

Uses a regenerable sorbent to simultaneously adsorb 

from coal-fired utility and industrial boilers. In the p

to a saleable sulfur by-product (liquid SO2, element

the NOx is converted to nitrogen and oxygen.

35 Copper-Oxide No No x x

Absorption and SCR. Experience limited to pilot scale.

SO2 in the flue gas reacts with copper oxide, suppo

alumina, to form copper sulfate. Ammonia is injecteabsorption reactor and a selective catalytic reductioreduces the nitric oxides in the flue gas. In the regensulfate is reduced in a regenerator with a reducing aproducing a concentrated stream of SO2.

36 Cold Plasma No No x Research Level

37 Biofilters Yes No x Research level

Gas stream is passed through a filter medium of soiadsorbed and degraded by microbial metabolism fodioxide and water.

38 Pahlman Process No No x Research Level

Gas stream is passed through a filter baghouse in wsmall-particle, high-surface area metal oxide sorbenPollutants are removed from the gases by adsorptio

1) This number is for reference only. It does not in any way rank the control technologies.2) a) Air Pollution: Its Origin And Control. Wark, Kenneth; Warner, Cecil F.; and Davis, Wayne T. 1998. Addison Wesley Longman, Inc.

 b) US EPA Basic Concepts in Environmental Science, Module 6, http://www.epa.gov/eogapti1/module6/index.htm c) New and Emerging Environmental Technologies, http://neet.rti.org/ d) ND BART Reports

Y:\23\38\131\NMC Process Boilers List of Control Technologies 2006-07-11.xls