Boiler Blog | Nationwide Boiler Inc.

Nationwide Environmental Solutions, a strategic business unit of Nationwide Boiler Inc., has extensive experience in SCR technology with over 100 installations across the country. We started out as a user on our rental boiler fleet, mastered the design and operation of the system, and began selling the superior product to our customers. We can now provide SCR systems for NOx reduction to as low as 2½ ppm for boilers, fired heaters, gas turbines, and other demanding applications.

Users in a diverse set of applications are experiencing changes in emissions regulations, driven by federal, tribal, and state implementation plans. With more stringent NOx control limits, utility and industrial industries are facing many challenges in achieving compliance. Selective Catalytic Reduction (SCR) technology has been emerging as a clear preference with new plant construction and retrofits to existing plants, and we want to help guide you to make smart decisions for your SCR design.

Join us on March 28th at 11AM EST for a live webinar, hosted by Director of Environmental Solutions, Sean McMenamin. Sean will discuss key considerations for your SCR design, including:

   - An overview of current and future anticipated NOx emissions regulations
   - Understanding NOx reduction control strategies and comparison of control technologies
   - Understanding "next generation" SCR design and performance expectations
   - NOx technology options utilizing alternative reagents
   - Operating conditions and their effects on SCR sizing, design and lifecycle costs
   - Various case studies

Register today! This is a webinar your won't want to miss.

Have you ever wondered what ppmvd (ref. 3% O2) means? This term is often seen in air permits and is referenced as the emission unit for pollutants such as NOx from boilers.

PPMVD stands for “parts per million by volume, dry”.  For example, “9 ppmvd” refers to (9 / 1,000,000) x 100 = 0.0009% of the volume of flue gas. The reason they stipulate “dry” is because when the emission is measured, the instrument typically removes all moisture (water) from the sample. The “ref. 3% O2” is required as a benchmark for the oxygen content in the flue gas. This is because the boiler will operate at various O2 levels, and the air district needs to normalize the measurements.

Sometimes, emission limits are referenced with different O2 levels for equipment in the same plant.  For example, on a boiler application, NOx may be listed as 9 ppmvd (ref. 3% O2) whereas for a gas turbine it might be 9 ppmvd (ref. 15% O2).  What does it mean when the O2 levels are different?

The difference in the example above is that O2 is referenced at 3% and 15%. Looking at actual numbers will help explain the difference. Let's say a boiler or gas turbine is firing natural gas and the heat input is 100 million Btu/hr. The fuel flow is the same for each case, about 4500 lb/hr. The air flow, however, will be different. 

For boilers, the burner typically runs at about 15% excess air (this is 15% extra air flow above the stoichiometric requirement). In other words, 15% of the air flow passes through the system without being oxidized. This is why the stack O2 (O2 is the extra oxygen in the boiler flue gas flow) is about 3% on a dry basis. This also explains why the 3% O2 benchmark is typically used.Based on the 100 million Btu/hr input and 15% excess air, the boiler air flow is about 81,000 lb/hr. 

On the other hand, gas turbines typically run at higher excess air levels as compared to boilers. To get 15% O2, dry in the stack, the excess air works out to about 230%. The air flow would be about 233,000 lb/hr with the gas turbine application. Stack flow, or the sum of fuel and air, differs in boilers vs. gas turbines:

Boiler stack flow:                            4500 + 81,000 = 85,500 lb/hr
Turbine stack flow:                         4500 + 240,000 = 244,500 lb/hr

You can see that for the same heat input of 100 million Btu/hr, the stack flow will be quite different for these two applications. This also explains why the O2 benchmark is different for these two cases. When comparing the NOx values in lb/mmbtu, we have:

9 ppmvd (ref. 3% O2) NOx firing natural gas is equivalent to 0.011 lb/mmbtu
9 ppmvd (ref. 15% O2) NOx firing natural gas is equivalent to 0.032 lb/mmbtu

This means that even though both 9 ppmvd volumetric numbers are the same, the numbers are actually different on a weight basis (i.e. lb/mmbtu).

Nationwide Boiler provides temporary and permanent solutions with our CataStak SCR System for boilers, gas turbines, and other demanding applications, to meet the most stringent emissions requirements. Contact us today for more infromation. 1-800-227-1966

Nationwide Boiler has been in business for over 50 years, and our business has seen tremendous growth since we first opened our doors in 1967. Starting out as a rental boiler company with just one boiler, we now maintain a rental fleet of over 100 boilers and related equipment, stock new and reconditioned boilers for sale, lead the industry in CataStak™ SCR installations for package boilers, own and operate a UL certified controls division based out of Washougal, WA, and provide many products and services above and beyond just boiler rentals.

So, when you think of Nationwide Boiler, don't think of us as just another boiler rental company. Check out these ten interesting facts that you may not have known about Nationwide:

1. Nationwide Boiler Inc. was originally named Nationwide Rentals, and began with just one 22,000 lb/hr trailer-mounted boiler in our rental fleet.
2. We maintain, service, and store our boilers in 10 key cities through the country to help achieve quick delivery and transportation cost savings.
3. We have over 20 sales representatives located throughout the world, ready to assist our customers.
4. Nationwide Boiler is more than just a rental company. In addition to stocking new and reconditioned boilers for sale, we also offer auxiliary equipment for rent and for sale. This includes CataStak™ SCR systems, EconoStak economizers, DataStak™ emissions & efficiency monitoring systems, deaerators, water softeners, heat exchangers, gas regulators, blowdown heat recovery systems, blowdown separators, and more.
5. The CataStak™ has been installed in over 200 temporary and permanent applications.
6. We stock a large inventory of boiler parts for quick delivery to our customers.
7. We provide complete boiler start-up, including operator training and operator service when required.
8. Our controls division, Pacific Combustion Engineering, has over 60 years of experience with all aspects of industrial heat processes, and can provide UL certified, integrated    burner management systems and combustion control packages.
9.  Nationwide Boiler is a manufacturer's representative for Babcock & Wilcox, Superior Boiler, E-Tech Heat Recovery Solutions, and Webster Combustion Technology.
10. Although we have 'Nationwide' in our name, we support customers worldwide and have provided equipment to six of the seven continents in the world. Can you guess which continent we have yet to check off our list?

Nationwide Boiler's Director of Environmental Solutions, Sean McMenamin, provided content for this month's issue of Process Heating Magazine. The topic of discussion this time around is reducing NOx emissions and improving overall boiler efficiency.

Sean has provided six tips to ensure the highest possible thermal efficiency, and lowest possible NOx output. This includes:

1. Reducing Stack Gas Temperature to Increase Efficiency
2. Managing Excess Air Levels for Optimum Performance
3. Utilizing Flue Gas Recirculation (FGR) to Reduce NOx Emissions
4. Selective Catalytic Reduction for Ultra-Low NOx Performance
5. Combining Economizers & SCR Systems for Emissions & Efficiency Gains
6. Monitoring Emissions & Efficiency Performance

For additional details related to these tips and tricks for reducing NOx and increasing efficiency, check out the full article in Process Heating's September 2018 issue!