March 15, 2007

Quality, Safety, and Cost Debated in NO_x Reagent Hot Topic Hour Yesterday

Utilities will be able to use the recording of yesterday’s Hot Topic Hour to give their engineers, operating personnel and even purchasing people comprehensive and up-to-date information on all the ramifications of NO_x reagent selection and use. There were six presenters each with lots of experience and each with different views.

Here are the highlights of the presentations and links directly to the power points used in the discussion and now in the NO_x Decision Tree.

Terra

Donald Thomas first provided detailed analyses of the NO_x reagent options and then cautioned viewers that there are substantial differences in product quality. There are big differences between the quality of anhydrous ammonia required for agriculture and that required for DeNO_x.

If a supplier is using the same equipment to handle both grades there will be contamination. This is compounded by the recent trend to add organic dyes and calcium nitrate to anhydrous ammonia in order to discourage illegal drug manufacture.

Oil from compressors is inevitably going to contaminate the anhydrous ammonia. Don displayed results at one plant where the level was consistently below 0.6 ppm vs. an industry average of 5 ppm.

Water quality control is essential in achieving acceptable aqueous ammonia. Terra recommends third party auditing and dedicated conveyances.

Formaldehyde is used to increase the solidity of urea, but can create Formica table tops in your handling system.

The TET urea liquor is free of formaldehyde. The demineralized water used exceeds ISO 3696 specifications. Terra has multiple production sites for this product. The comprehensive power points are displayed in the NO_x Decision Tree and can be found through the following link.

Continuing Decision Process For: NO_x Reagents

Comparison of Anhydrous Ammonia, Aqueous Ammonia and Urea

http://www.mcilvainecompany.com/NOx_Decision_Tree/subscriber/Tree/DescriptionTextLinks/CostAnalyWashGrp.pdf
 

Ammonia Options

http://www.mcilvainecompany.com/NOx_Decision_Tree/subscriber/Tree/DescriptionTextLinks/TET Users Group 2007.htm

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Vector Systems, Inc.

Dustin Divinia emphasized all the pitfalls due to impure water in aqueous ammonia. He also detailed a number of the critical component and system selections to ensure a reliable and safe reagent delivery system. His presentation is found in the NO_x Decision Tree as follows:

Continuing Decision Process For: Aqueous Ammonia

Ammonia Quality by Vector Systems, Inc.

http://www.mcilvainecompany.com/NOx_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Ammonia Equipment Maintenance.htm

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Cervantes-Delgado

Luis Cervantes emphasized the importance of local reagent supply. The company now can supply reagent from 30 locations. Information on the company and locations is displayed in the following branch.

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EC&C Technologies, Inc.

Bert Spencer indicated that plants in rural areas as well as those near or in cities should consider urea as a reagent. The U2A urea to ammonia system is licensed to Wahlco and Hamon Research Cottrell and is being used by a number of utilities. His presentation is displayed at

Continuing Decision Process For: Urea

U2A® Experience with Urea-Based Ammonia Systems by EC&C McIlvaine Hot Topic NO_x Reagents

http://www.mcilvainecompany.com/NOx_Decision_Tree/subscriber/Tree/DescriptionTextLinks/EC&C - U2A presentation March 15, 2007.htm
 

Ammonia on Demand at AEP

http://www.mcilvainecompany.com/NOx_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Final_Hamilton.pdf

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Peerless

Sean McMenamin explained that Peerless viewed reagent issues from the perspective of a supplier of reagent storage and handling equipment. They supply complete SCR systems or just the ammonia delivery and injection portion. Pictures and good rule of thumb factors are found in the following branch.

Continuing Decision Process For: Products

Reagent Storage & Handling Equipment

http://www.mcilvainecompany.com/NOx_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Storage and Handling - Peerless.htm
 

Equipment Design

http://www.mcilvainecompany.com/NOx_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Peerless Slides (2).pdf

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Fuel-Tech

Kevin Dougherty summarized the reagent alternatives as follows:

• Anhydrous Ammonia

- Highest risk reagent

- Decrease in U.S. ammonia production

- Future availability question – rail issue

• Aqueous Ammonia

- 19% Concentration

- 29% Concentration – limited availability

• Urea for On-Site Ammonia Generation

- Significant Safety Advantages

- Worldwide Availability of Urea

- Equivalent SCR Performance

- Safe Transportation, Handling, and Storage

- Fewer Issues with Site Permitting and Local Politics

§         Large SCRs in Rural Areas using Safe Reagent for SCR

- Market Pricing Control versus Ammonia

§         Supply Flexibility

o       Worldwide Availability of granular Urea

§         On-site Solutionizing

o       Urea Liquor, 60% Concentration – Dilute and Store

o       40% Urea Solution Delivered to site

Kevin provided an interesting display of global natural gas prices. The low cost of natural gas in other parts of the world should dictate favorable imported urea prices in the U.S.

Kevin also cited some of the advantages of using urea for SNCR. The droplets can be projected much farther into the furnace than is possible with ammonia. This ensures better distribution.

Continuing Decision Process For: Urea

NO_x Reagent Issues

http://www.mcilvainecompany.com/NOx_Decision_Tree/subscriber/Tree/DescriptionTextLinks/McIlvaine NOx Reagent Issues Fuel Tech.htm
 

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Breen Energy Solutions

Ben Breen addressed three technologies related to NO_x reduction: He explained that

§         Fuel-Lean Reburn enhances SNCR because it

o       Lowers O₂ locally in the vicinity of amine,

o       Fuel hydrocarbon reacts with NO,

o       Provides additional HCN & HN.

§         The advantages of Coal/Water Slurry injection with SNCR

o       Compatible with existing SNCR,

o       Lower cost and increased NO_x Reductions,

o       Can operate without urea/ammonia (based on credit value),

o       Can use wastes for fuel credits (high carbon ash, biomass).

§         The slurry injection also generates activated carbon (AC) for mercury capture

o       Increased chlorine (halogenation of AC) and oxidation,

o       Improved carbon high temperature capture.

BES developed an Ammonium Bi-Sulfate (ABS) Fouling Detection Probe which can be used for SCR/SNCR Optimization.

BES has also invented a low cost, local heat flux monitor that can distinguish ash accumulation and its condition. Thus BES relates impingement and ash accumulations to individual burner adjustment. This presentation is found at:

Continuing Decision Process For: Products

Lowered NO_x Operation

http://www.mcilvainecompany.com/NOx_Decision_Tree/subscriber/Tree/DescriptionTextLinks/Lowered NOx Operation 3-13-07 Breen.htm

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Airgas

Jodi Crawford, Marketing Manager, Airgas Specialty Products was not able to participate directly but answered the questions we posed as follows:

• What differences in anhydrous ammonia quality are important to operations and maintenance? 

Aqueous ammonia concerns center primarily on water quality. In order to avoid buildup in spray nozzles from minerals in water, the water used in the aqueous manufacturing process should be free from impurities. 

For anhydrous, the primary concern would be residual oil and water buildup in the tank. This can be prevented by using a pure form of ammonia- premium grade- or with regular pump-down of the tank.  Both options can be provided by Airgas.

• What about future availability with 12 month operation? 

The vast majority of ammonia is used in agriculture. Ammonia used in DeNO_x accounts for about three percent of consumed ammonia. Therefore the availability of ammonia supply, particularly outside of fertilizer seasons (early spring and fall), should be of little concern.

• What is the price differential between aqueous, anhydrous, and urea? 

In terms of consumables, anhydrous is by far the most cost effective product. Depending on corporate strategy and local demands, alternative products are used despite the cost impact.

Aqueous ammonia is more expensive in part due to the SCR or reagent quality water, but also due to the freight disadvantage of shipping water.  For a facility close to an aqueous manufacturer, aqueous costs are generally 20-25% higher than anhydrous. As distance increases, the freight disadvantage increases significantly.  As an average we estimate a 30% cost disadvantage for aqueous vs. anhydrous. 

Aqueous also requires greater storage capacity to meet the same NO_x requirement, though there are regulatory and handling advantages for aqueous ammonia. 

Urea availability and therefore pricing is more volatile than ammonia. While a non-hazardous product, there are unique handling difficulties that increase storage and maintenance costs well above aqueous ammonia. For instance, urea tanks holding a 50% solution will salt out at 63°F and must be heated. A 65% solution will salt out at 115°F.

• What options are available for on-site conversion of urea to ammonia? 

While a non-hazardous product, urea poses certain handling difficulties, particularly in colder climates.  Liquid urea solutions must be kept hot or they will salt out and form very hard solids in tanks, piping, and nozzles.

There are buildup and residue concerns in urea to ammonia conversion, and as with aqueous ammonia, water quality will be important.

A delivery infrastructure for urea liquor, which may reduce handling difficulties, has not yet matured.  As manufacturers develop efficiencies in delivering high percentage (70%) liquor, availability of various lower concentrations will improve.

Dry urea can also form a solid when not handled properly, creating additional handling obstacles for plant personnel that should be focused on operating the plant- not manufacturing a reducing agent.

If a facility is committed to ammonia to urea conversion, using liquid urea with a storage system will minimize the burden on O&M personnel. 

• What are the safety concerns and how do you address them? 

Ammonia is an inhalation hazard.  We address the concerns associated with such a system by

1.      Implementing the safest known technology for ammonia delivery and storage systems.

2.      Training, training, training.

• What are the best guidelines for on-site storage? 

Speak to an ammonia supplier who will be familiar with operating and delivery procedures. Engineering firms may have difficulty in foreseeing circumstances that are routinely a part of ammonia storage and delivery.  You will find that certain adjustments will save time, headaches, and expenses for operating and maintenance.  It is worth seeking the knowledge. We often assist in reworking ammonia storage after the unit is operational, a process that may be less expensive and certainly less troublesome if handled during the design phase.

• What packages are available from suppliers?

From cylinder delivery to railcar and anything in between.