CataStak FAQs

Nationwide Environmental Solutions wants to ensure that you have the answers to all of your questions. If you have a question you would like answered, please contact us.

What applications can the CataStak™ SCR system be used for?
The CataStak™ SCR system can be applied to boilers, gas turbines, heaters, furnaces, steam generators, thermal oxidizers, and other applications that can benefit from NOx reduction achieved from SCR technology.  The CataStak™ SCR system has been utilized in various industries worldwide, 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 up to 99% reduction on gas-fired 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 produced through the use of a SCR technology. 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, plate or honeycomb form.  The catalyst material is typically made of vanadium pentoxide, tungsten trioxide and/or titanium dioxide.  All types of catalyst are considered to provide optimized performance in meeting the customer’s need.

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, however special care and consideration must be taken when handling catalyst.  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 300 - 950°F, with special consideration for projects operating outside that range. Ultimately each solution will vary from one application to another.

What can damage the catalyst?
Several items can lead to damage of the catalyst, including immersion in water, contact with any poisonous substances, and 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 an economizer (boiler applications) and the exhaust stacks. This is commonly referred to as a post combustion (back-end) solution.

What is the layup (out of service) procedure for the catalyst?
For boiler applications, 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.  Consult Nationwide for additional requirements.

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) to control the flow of ammonia.  The Nationwide Ammonia-Free CataStak™ SCR system requires additional controls, as needed for the injection of urea.

What can I expect for boiler 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?
For smaller applications, ammonia is typically supplied to the system by three 150 lb. ammonia cylinders stored on an ammonia skid.  Based on the ammonia demand, storage tanks and forwarding systems can be supplied.

Is an ammonia-free option available?
Nationwide’s Ammonia-Free CataStak™ is the proven alternative to traditional ammonia based SCR systems, utilizing a 32.5% aqueous urea solution as the system’s reagent.

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 a urea to ammonia system can be installed.  Such a system uses urea as the feedstock chemical and it avoids transportation or storage of ammonia.

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 will be provided by Nationwide Environmental/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.