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FAQs

What applications can the CataStak™ SCR system be used for?
The CataStak™ SCR system can be applied to boilers, fired-heaters, steam generators, gas-turbines, heaters, furnaces, OTSGs and other demanding applications.  The CataStak™ SCR system has been utilized in various industries ranging from petrochemical, refining, food processing, utilities, universities and pulp and paper industries.

What are the NOx conversion capabilities of the CataStak™ SCR system?
The NOx conversion capabilities of the CataStak™ SCR system can be greater than 95% on gas-fired boiler applications and up to 99% for nitric acid applications.  Most applications are designed for 5 ppm NOx outlet and Nationwide has successfully obtained 5 ppm NOx or less in over 100 installations.

What is ammonia slip?
Ammonia slip is the release of unreacted ammonia. Several factors affect the amount of ammonia slip including the original system design, the amount of catalyst, flow rate and temperature.  The CataStak™ SCR system typically can achieve less than 5 ppm ammonia slip for most applications.

What is the catalyst made of?
Nationwide’s CataStak™ SCR system's catalyst can be in a pelletized or honeycomb form.  The pelletized catalyst material is made of vanadium pentoxide and titanium dioxide.  Both types of catalyst provide optimized performance.

How long does the catalyst last?
The catalyst can last up to ten years in a clean gas application.  Nationwide’s typical performance warranty is three years.

How do I dispose of spent catalyst?
Spent catalyst can safely be disposed of in an approved landfill.  Consult your local facility for more information.

What is the temperature range of the CataStak™ SCR system?
The typical temperature range of the CataStak™ SCR system is 325 - 750°F.

What can damage the catalyst?
Several items can lead to damage of the catalyst including immersion in water, contact with any poisonous substances, fouling or plugging of the catalyst by particulate or excessive temperatures above the normal operating range of the catalyst.

What equipment arrangements are available for the CataStak™ SCR system?
The CataStak™ SCR system can be arranged either vertically or horizontally, before placement of the economizer in most applications. This is commonly referred to as a post combustion (back-end) solution.

What is the layup (out of service) procedure for the catalyst?
The layup procedure for the catalyst is to simply cap the stack in order to keep rain out.  Heaters are not necessary when out of service.

What controls are needed for the CataStak™ SCR system?
The controls needed for the CataStak™ SCR system is a repeatable control signal from an existing gas valve (4-20 ma).  Nationwide Boiler’s “patent-pending” NOx Reduction Control System is included with the CataStak™ SCR system.

What can I expect for turndown?
The CataStak™ SCR system operates at all boiler turndown ranges.  Whatever your boiler does the CataStak™ SCR system will track.
 
What about pressure drop?
The CataStak™ SCR system can be designed for 1”- 4” wc pressure drop requirement.  2” wc is typical.

How is ammonia supplied to the system?
Ammonia is typically supplied to the system by three 150 lb. ammonia cylinders stored on an ammonia skid.
 
Are any HAZMAT programs required due to the ammonia?
HAZMAT programs are not required if the ammonia storage of the CataStak™ SCR system does not exceed 500 lbs.  If 500 lbs. or more of ammonia is stored, then HAZMAT is required. Please consult Nationwide for additional details.

What if I do not want to store ammonia for my system?
If ammonia storage is an issue then an urea to ammonia system can be installed.  Such a system uses urea as the feedstock chemical and it avoids transportation or storage of ammonia.  Nationwide Boiler also offers an ammonia-free option for boilers.  Contact Nationwide Boiler for additional details.

How should the CataStak™ SCR system be operated?
The CataStak™ SCR system is fully automated and minimal operator intervention is needed for typical operation, except for the safe handling of ammonia when replacing the ammonia cylinders.

Who provides start-up service?
Start-up service should be provided by Nationwide Boiler or an approved start-up technician.

What are the typical installation costs of the CataStak™ SCR system?
Installing a CataStak™ SCR system is very similar to installing an economizer (in most instances).  Costs can vary greatly depending on the orientation (vertical or horizontal), civil / structural issues and size. Please contact us and we would be happy to discuss this with you.

What is the typical delivery time horizon of the CataStak™ SCR system?
Normal delivery for the equipment is twenty (20) weeks, plus two (2) to four (4) weeks installation and commissioning services. Please consult Nationwide for additional details.

What installation services are available?
Installation services can be provided by Nationwide Boiler or a local contractor.

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