Typical Installation Timelines

for 

NOx Emissions Control Technologies 

on

Industrial Sources

Institute of Clean Air Companies

1730 M Street NW

Suite 206

Washington, DC 20036-5603

Telephone 202.457.0911

Fax 202.331.1388

David C. Foerter, Executive Director

Chad S. Whiteman, Deputy Director

December 4, 2006
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About the Institute of Clean Air Companies

The Institute of Clean Air Companies (ICAC) is the national trade association of companies that 

supply air pollution control and monitoring technologies for stationary sources who provide 

solutions for a broad range of industrial applications as well as electric power plants. ICAC 

represents more than ninety of the leading manufacturers who provide emissions control 

solutions for affected industries as well as employment opportunities across the U.S. ICAC 

gives the air pollution control and monitoring industry a responsible and responsive presence in 

Washington, DC and throughout the country, which works constructively with government, 

business, public, and private groups to ensure that the air pollution control industry and its 

products are properly represented and understood. 

Introduction

The following document provides information concerning the time needed for the installation of 

emissions control technologies for industrial sources. The document focuses on the deployment 

time of NOx controls that are applied to various industrial categories including the following: 

low NOx burners, selective non-catalytic reduction, selective catalytic reduction, and nonselective catalytic reduction. The information below can be used as a general guide for the 

typical time required to complete a typical NOx control project from the initial bidding period 

through the start-up of the installed control technology. The level of retrofit difficulty and site 

specific conditions may increase or decrease the time required for the deployment of the control 

technology.

There are several points in the NOx control technology deployment process where the end user 

dictates the amount of time consumed. For example, control technology manufacturers rely on 

the end user during the bid evaluation, project negotiation, review of engineering drawings, 

review of flow modeling studies (if applicable), scheduling the outage (if applicable), and 

compliance testing steps. For these steps, the end user is in control of the time required to 

complete each step as opposed to the emissions control manufacturer. For example, the timing 

of the initial bid evaluation and negotiation may vary depending on the amount of resources the 

end user has available to review and proceed with the decision making process or the amount of 

time prior the end user has prior to meeting a compliance deadline. The following deployment

timelines have assumed that the affected source has decided to move forward with the 

installation of the control technology and is working with emissions control manufacturers to 

move the project forward in a reasonable timeframe. 

Low NOx Burners and Flue Gas Recirculation

There are a number of types of combustion control technologies that have been applied to 

industrial sources depending on the application and emissions requirement. The deployment 

times for two of the combustion control technologies including low NOx burners (LNB) and 

LNB in conjunction with flue gas recirculation (FGR) are discussed below.

Low NOx Burners - For coal-, oil-, and gas-fired boilers, low NOx burners decrease the air 

introduced into the primary combustion zone thereby creating a fuel-rich environment and lower 
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combustion temperatures that work to lower NOx formation. Conventional burners operate with 

excess combustion air when compared to the stoichiometric requirement for complete 

combustion. When applying low NOx burners, the percentage of excess air is reduced in the 

primary combustion zone with the remaining air required for complete burnout of combustibles 

added where the temperature is sufficiently low so that additional NOx formation is minimized. 

Ultra Low NOx Burners are an advanced generation of low NOx burners that provides additional 

NOx reductions through improved designs.

LNB + Flue Gas Recirculation - Flue gas recirculation reduces NOx emissions by recirculating

and mixing 5-40 percent of the boiler flue gas with the combustion air prior to combustion in the 

main combustion chamber. This process reduces the peak combustion temperature and lowers 

the percentage of oxygen in the combustion air/flue gas mixture; thus retarding the formation of 

thermal NOx caused by high flame temperatures. FGR is often used in combination with LNB to 

reduce NOx emissions below levels that may be achieved by using LNB alone. FGR has been 

applied to natural gas, kerosene, distillate oil, and coal-fired boilers.

The deployment time for retrofitting an existing boiler with LNB or ultra-LNB is relatively short

due to the simplicity of the technology and the small number of burners on most industrial 

boilers. The vast majority of oil- and gas-fired package boilers used for various industrial 

applications have just one or two burners making the retrofits less intensive. A complete LNB 

system retrofit typically includes the following major components: windbox, burner(s), and 

burner management system. LNB manufacturers typically design their systems to keep the 

retrofit cost to a minimum by replacing only critical firing components, while keeping most of 

the burner system intact. For example, a LNB manufacturer may design their LNB system to 

adapt to the existing windbox geometry, backup fuel firing system, and ignition equipment. By 

minimizing the changes of equipment, LNB manufacturers minimize the amount of time 

required for the retrofit. 

Retrofitting an existing industrial boiler with flue gas recirculation involves installation of a 

system to extract the flue gas from the boiler unit, ductwork, and fan. The deployment of a 

complete LNB + FGR system will include: windbox, burner(s), burner management system, 

potentially larger fan for FGR, and ductwork for FGR. A fly ash control device is necessary for 

coal-fired applications in order to clean the flue gas of particulate matter prior to recirculation of 

the gases back into the boiler. Retrofitting existing oil- and gas-fired boilers with flue gas 

recirculation involves all of the same components except for the fly ash collecting device. 

For a complete system, the typical deployment of LNB or LNB + FGR takes between 24-32 

weeks (6 – 8 months) on a typical industrial boiler covering the bid evaluation through the startup of the technology. The deployment schedule for complete LNB or LNB + FGR technology 

on a typical industrial boiler can be divided into the following timeframes:

• 4-8 weeks – bid evaluation and negotiation 

• 4-6 weeks - engineering and completion of engineering drawings

• 2 weeks – drawing review and approval from end user

• 10-12 weeks – fabrication of equipment and shipping to end user site
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• 2-3 weeks – installation at end user site (Most of the components of the technology can 

be installed while the boiler is operating. The boiler may be required to shut-down for 1-

2 days for a simple burner change-out or as much as seven days for a complete system 

installation.) 

• 1 week – commissioning and start-up of technology

Variations in the schedule may occur due to site specific conditions that may increase or 

decrease the typical deployment time. The typical deployment time is short for systems that can 

use the existing burner management system, windbox, and other components and replace just the 

burner(s). For these applications, the deployment schedule may be as little as 12-16 weeks if 

only the burner(s) are being replaced. 

Selective Non-Catalytic Reduction 

Selective non-catalytic reduction (SNCR) is a chemical process for removing NOx from flue gas. 

In the SNCR process, a reagent, typically urea or anhydrous gaseous ammonia is injected into 

the hot flue gas and reacts with the NOx, converting it to nitrogen gas and water vapor. The 

chemical reaction for this technology is driven by high temperatures, typically from 1,600 –

2,100 °F, normally found in combustion sources. SNCR is “selective” in that the reagent reacts 

primarily with NOx.

SNCR may be combined with low NOx burners (LNB), over-fire air (OFA), neural networks, 

rich reagent injection (RRI), selective catalytic reduction (SCR) systems, or with gas reburn 

technologies to provide additional emissions reductions. Combined SNCR/SCR systems are 

finding new applications allowing higher overall NOx reduction than SNCR alone and lower 

ammonia slip.

The principal components of the SNCR system are the reagent storage and injection system, 

which includes tanks, pumps, injectors, distribution modules, and associated controls. The 

combustion unit acts as the reactor chamber simplifying the SNCR process. The reagent is 

generally injected within the boiler superheater and reheater radiant and convective regions, 

where the combustion gas temperature is at the required temperature range. The number of 

injection ports and location is determined by flue gas flow and temperature profiles. 

SNCR is a proven and reliable technology. SNCR was first applied commercially in 1974 and 

has been installed on approximately 400 applications worldwide. Applications include utility 

boilers and a broad range of industrial applications including installations on the following: 

wood-fired boilers, coal-fired boilers, co-generation boilers, pulp and paper boilers, steel 

industry furnaces, refinery process units, process heaters, cement kilns, municipal waste 

combustors, glass melting furnaces, hazardous waste incinerators, and other combustion sources. 

Urea-based SNCR has been applied commercially to sour ces ranging in size from a 60 mmBtu/hr 

(gross heat input) paper mill sludge incinerator to a 640 MWe pulverized coal-fueled, wall-fired 

electric utility boiler. 

Given the simplicity of the SNCR system components, installation of SNCR is relatively easy 

and can be done in a relatively short period of time. It typically takes between 42-51 weeks (10-
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13 months) to complete the SNCR project going from the bid evaluation through start-up. Under 

special circumstances and during periods of lower SNCR manufacturer activity, SNCR 

installations are typically completed in eight (8) months. A typical timeline for the completion 

of an SNCR projection starting from the commercial request for quote (RFQ) to the compliance 

testing is given in Table 1 below. Certain steps in the SNCR installation process have 

prerequisite steps while others may occur simultaneously. Below is a brief description of some 

of the aspects of the SNCR project timing: 

1) Initial Stages of Planning and Development

a) Bid Evaluation – After the end user submits the request for quote (RFQ), the APC 

manufacturer will take typically take between 2-4 weeks to submit the proposal. The 

APC manufacturer relies on the end user to provide the appropriate information 

concerning the application in order to provide the design proposal. Some end users have 

in-house engineering resources that are make this process run more efficiently.

b) Initial Engineering – Once the bid has been accepted, the initial engineering for the site 

will typically take between 1-4 weeks and is typically completed 4-8 weeks from the 

commercial RFQ date. The initial engineering will include things like the design of any 

concrete work for the reagent storage tanks and distribution system, placement of control 

systems, siting power delivery, etc.

c) Modeling & Engineering Drawings – Computational fluid dynamic (CFD) modeling and 

engineering drawings are typically completed 18 weeks after the RFQ. The CFD 

modeling will help determine the number and location of the reagent injection ports that 

will be incorporated into engineering drawings. Initial engineering drawings are 

produced by the APC manufacturer and submitted to the end user for comment. The 

APC manufacturer addresses the comments and prepares the general arrangement 

drawings. 

2) Procurement, Fabrication, Shipping – The procurement, fabrication, and shipment of the 

various components of the SNCR system will typically be completed by the 34th week from 

the RFQ. It typically takes between 16-20 weeks for this phase of the project. Some of the 

typical components that will need to be procured for the SNCR system include: urea 

solutionizing equipment (if applicable), reagent storage tank, injection lances, reagent control 

system, reagent pumps, reagent distribution piping, etc. Once the items have been procured, 

some of the components will need to be assembled prior to shipment including: reagent 

distribution models and piping, pump skid, process control skid, etc. The equipment is 

usually small enough to be shipped by truck upon assembly. The timing for shipment 

depends on the relative distance from the fabrication shop to the end user’s site.

3) Equipment Installation – The equipment installation will typically be completed 42 weeks 

from the RFQ. Once the original engineering is complete at the end user site and the 

fabricated components arrive on-site, the equipment installation will take between 8-12

weeks not including the outage. Most of the equipment installation will be completed while 

the unit is operating. An outage of between 7-14 days may be required to install the reagent 

injection ports and lances in the combustion chamber. Usually, the work is done within an 

outage taken for other scheduled reasons. The amount of time taken for injection port 

installation will vary depending on the type of SNCR installation and the availability of

existing ports on the combustion unit. If ports on the combustion unit are already in place, 

then the time needed to install the injection lances will be at a minimum. 
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4) Equipment Start-Up – Once all of the equipment has been installed, there will be a period of 

start-up, optimization, and compliance testing that will typically be completed some time 

between the 42nd and 51st week from the RFQ. It typically takes 2-4 weeks to complete the 

start-up after the installation; 2-4 weeks for the optimization; and approximately 3 weeks for 

the compliance testing. 

SNCR Project Activity Responsibility

Weeks from 

Commercial RFQ 

Date

RFQ Issued Customer 0

APC Manufacturer Issues Proposal Customer 2-4

Bid Evaluation and Negotiation Customer 4-8

Receipt of Purchase Order Customer 8

Begin Equipment Design APC Manufacturer 9

Begin CFD/CKM Modelinga APC Manufacturer 9

Submit P&ID Drawingsb APC Manufacturer 12

Customer P&ID Drawing Review and Comment Customer 14

Submit General Arrangement Drawings APC Manufacturer 16

Submit Modeling Report APC Manufacturer 16

Customer Comments Received Customer 18

Start Equipment Fabrication APC Manufacturer 18

Equipment Shipment APC Manufacturer 34

Installation Complete

(Outage work for injection port installation) TBD

8 to 12 weeks 

(Non-Outage)

1 to 2 weeks 

(Outage)c

Startup Complete APC Manufacturer 42 to 46 weeks

Optimization Complete APC Manufacturer 44 to 48 weeks

Compliance Testing Complete Customer 47 to 51 weeks

a

- Computational fluid dynamic modeling provides in-depth analysis of a complex fluid flow, including detailed flow 

characteristics (velocity, pressure, turbulence, temperature, species concentration) for process optimization.

b

– P&ID drawings are process flow and instrument drawings that show process flow paths for liquids, solids, and electrical 

systems. 

c

- The injection port installation is done within an outage taken for other scheduled reasons and typically takes from one to two 

weeks. The injection port installation may be performed at the same time as other equipment fabrication or during another period 

of the SNCR project and may not add more time to the overall length of the SNCR project.
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Selective Catalytic Reduction

Selective catalytic reduction (SCR) technology has been practiced worldwide for over 50 years 

with hundreds of successful applications in a broad field of industrial applications. Selective 

catalytic reduction technology has been successfully applied to a wide variety of combustion and 

chemical process operations including: gas turbines, stationary spark ignition engines, stationary 

compression ignition engines, refinery heaters, packaged boilers, ethylene cracker furnaces, 

nitric acid plants, catalyst manufacturing processes, nitrogen fixation processes, and solid/liquid 

or gas waste incineration equipment. The experience with SCR on industrial applications has 

been throughout the United States, with high concentrations in California, New Jersey, and 

Texas due to their more stringent NOx requirements. SCR has been used by itself and in 

combination with other technologies, such as SNCR, LNB, and FGR. 

The principal of operation for an SCR system is to inject a reducing agent into the hot flue gas 

upstream of a catalyst. The catalyst accelerates the reaction of the reducing agent with NOx and 

is used to broaden the range of operating conditions, market applications, and NOx destruction 

efficiencies achievable. The catalyst promotes the selective reaction of NH3 with NOx, forming 

nitrogen and water. Depending on the manufacturer’s system, the catalyst may be a packed bed 

of pellets, extrudates or other particulate shapes, or as rigid honeycomb or plate type cubes that 

are assembled to form the catalyst bed. The reducing agent for SCR can be anhydrous ammonia, 

aqueous ammonia, or urea. Care is taken to inject the amount of reducing agent equal to the 

amount of NOx in the stream to avoid excess ammonia, or ammonia slip. On most SCR 

applications, the flue gas temperature for optimum NOx reduction is typically achieved between

500-1,000 oF. Catalyst designs can be tailored for the applications specific temperature window. 

For gas-fired boiler applications, catalysts have been designed for optimum performance at lower 

temperatures between 300-700 oF. 

For smaller applications where the exhaust flow rate is 20,000 SCFM or less, SCR systems are 

supplied in a ready-to-install SCR skid package. SCR skid packages are typically applied on 

packaged boilers, engines, some chemical processes, etc. In addition, standard SCR packaged 

systems are available for the complete range of firetube and watertube boilers as well. The 

primary components of the SCR system include: ammonia storage and delivery system, 

ammonia injection grid, and catalyst reactor. The ammonia injection grid and SCR catalyst can 

often be installed immediately before or in the stack, thereby avoiding any modifications to 

combustion or heat-recovery equipment or negative effects on other upstream plant operations. 

For larger applications of 20,000 SCFM or greater, designs permit a modularly constructed 

system, providing a high degree of flexibility in the design of the SCR system for the specific 

application, particularly for retrofit applications. This has made the SCR technology a costeffective retrofit technology for gas-fired industrial boilers, larger chemical installations, 

distributed generation facilities, and major waste incineration plants. 

Installation timing for SCR often depends on the size of the application and will be discussed in 

terms of those units that have flue gas flowrates less than 20,000 SCFM and those greater than 

20,000 SCFM. Since smaller systems are skid mounted and designed for quick installation in the 

field, the deployment process from bid through startup takes significantly less time than a larger 
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field erected system. The following table lays out the SCR deployment time from the request for 

quote issued by the end user to the optimization and compliance testing. 

Weeks From Commercial RFQ Date

SCR Project Activity <20,000 SCFM 

SCR System

>20,000 SCFM 

SCR System

RFQ Issued 0 0

APC Manufacturer Issues Proposal 1-3 2-4

Bid Evaluation and Negotiation 2-6 4-8

Receipt of Purchase Order 6 8

Client Kick Off Meeting 7 9

Customer GAa & P&ID Drawing Review and 

Comment 9-10 16-20

Drawing Review w/Customer 11-12 18-24

Start Equipment Fabrication 12-13 20-24

Equipment Shop Tested 22-23 36-40

Equipment Shipment 23-24 38-42

Field Installation Complete 26-30 44-52

Startup Complete 27-32 46-56

Optimization & Compliance Testing 28-36 48-58

a

GA – general arrangement drawings are scaled, dimensioned, and annotated to reflect a reasonable layout for the project.

In summary, smaller skid-mounted SCR systems can be supplied from RFQ to compliance 

testing in 7-9 months or in approximately six (6) months from the purchase order to startup. 

Most of this time is spent in engineering design, fabrication, and field installation. Larger SCR 

systems that are field erected from modular components are typically supplied from RFQ to 

compliance testing in 11-13 months or in 9-12 months from the purchase order to startup. 
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Non-Selective Catalytic Reduction (NSCR)

Stationary NSCR, as with the automobile sector, involves the use of a three-way catalyst 

technology to promote the reduction of NOx to nitrogen and water and simultaneous oxidation of 

CO and HC to carbon dioxide and water. NOx is reduced by the CO and H2 over the catalyst 

under slightly rich or stoichiometric conditions to produce CO2 and water with typical 

conversion efficiencies in the range 80-99 percent achievable together with corresponding 

decreases in HC and CO. 

Non-selective catalytic reduction (NSCR) can be applied to various spark ignited internal 

combustion engines that are rich-burn, including natural gas-fueled engines. These types of 

engines are commonly found in the following applications: gas gathering and storage, gas 

transmission, power generation, combined heat and power, cogeneration/trigeneration, irrigation, 

inert gas production, and non-road mobile machinery. NSCR has been used routinely in the 

automotive industry to reduce vehicular carbon monoxide, hydrocarbons, and NOx emissions 

with over a billion catalyst units equipped to automobiles since the mid-1970s. The application 

of NSCR to stationary gas engines for the control of NOx and CO first became commercially 

available in North America in the late 1980s and have well over 5,000 stationary engine 

installations in service today. 

In addition to catalysts and housings (converters), NSCR retrofits require installation of an 

oxygen sensor and feedback controller to maintain an appropriate air-to-fuel ratio under variable 

load conditions. The catalyst applied to NSCR typically contains active metals such as platinum, 

palladium, and rhodium and is typically in the form of highly durable metallic monolith 

elements. NSCR converters are available off-the-shelf for very short turn-around installations. 

The time required for the deployment of off-the-shelf NSCR products is 6 to 8 weeks and for 

standard products, 8 to14 weeks with the following steps:

• 2-4 weeks - bid proposal and evaluation

• 4-6 weeks – engineering and shipping

• 1-2 weeks – installation 

• 1-2 weeks – start-up
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MEMBERS

Members

ADA Environmental Solutions, LLC

ALSTOM Power

Argillon LLC

Babcock & Wilcox

Babcock Power Inc.

BASF

Belco Technologies Corporation

Black & Veatch

Burns & McDonnell

Chemical Lime Company

Cormetech, Inc.

CRI Catalyst Company

CSM Worldwide, Inc.

Dürr Environmental & Energy Systems

Epcon Industrial Systems

Forney Corporation

Fuel Tech

GE Energy Services

Haldor Topsoe, Inc.

Hamon Research-Cottrell, Inc.

Hitachi Power Systems America, Ltd.

Hitz America Inc.

Horiba Instruments, Inc.

Johnson Matthey Stationary Source Emissions Control

Land Instruments International, An AMETECK Co.

Marsulex Environmental Technologies 

Mitsubishi Power Systems, Inc.

Mobotec USA, Inc.

Ohio Lumex

Powerspan Corporation

Sargent & Lundy, LLC

SICK Maihak, Inc.

Spectrum Systems, Inc.

Stone & Webster Engineering Corporation

Süd-Chemie, Inc.

Tekran Instruments Corp.

Teledyne Monitor Labs

Thermo Electron Corporation

Washington Group International, Inc.

Wheelabrator Air Pollution Control

WorleyParsons 

Associate Members

Advanced Electron Beams

Airflow Sciences Corporation

Airgas, Inc.

Andover Technology Partners

Applied Ceramics, Inc.

Aspectrics

Avogadro Environmental Corporation

Baldwin Environmental, Inc.

California Analytical Instruments

Carmeuse North America

Casey Industrial, Inc.

CEM Service Group, Inc.

Chemco Systems LP

Corning, Incorporated

Dekoron/Unitherm, Inc.

ECOM America Ltd.

Energy Services Consultants

Environmental Systems Corporation

Evergreen Energy

FFE Minerals

FlowTack, LLC

Graymont Inc.

GT&S, Inc.

Linde Gas, LLC

M&C Products Analysis Technology, Inc.

Matheson Trigas, Inc.

McIlvaine Company

Midwesco Filter Resources, Inc.

Millennium Chemicals, A Lyondell Company

NORIT Americas Inc.

NWL Transformers

Parker Hannifin, Parflex Division

Perma Pure

Praxair, Inc.

PSP Industries

Rauschert Process Technologies, Inc.

Restek Corporation

RJF Consultants, LLC

Scott Specialty Gases, Inc.

SCR-Tech

Solvay Chemicals, Inc.

Spectra Gases, Inc.

Structural Steel Services, Inc.

Terra Environmental Technologies

Testo, Inc.

Thermon Manufacturing Co.

TLT Babcock Inc.

Universal Analyzers, Inc.

VIM Technologies, Inc.

VIG Industries, Inc.

Zachry Construction Corporation