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

With California having the most stringent emissions requirements in the country, it is important to be well versed on any and all rules and regulations when buying a new boiler or renting a temporary boiler. This is our final installment of the 3-part series on air permit compliance for boilers in California (be sure to check out part 1 and part 2 if you haven’t already).

Nationwide Boiler maintains a fleet of rental units that are sub-9 ppm NOx and pre-permitted for use in the SCAQMD. We take care of the bulk of the permit work saving our customers an exponential amount of time (no waiting for the application to be approved), and we pay for any processing fees. This allows for quick installation and start-up of a temporary boiler, which is extremely valuable in an emergency outage. The only requirement of our customer is the source testing of the equipment, if the source test is due. Most of these pre-permitted boilers require source testing on an annual basis, and the source test must be done at a job site within the county’s jurisdiction.

The SJVAPCD does not allow the pre-permitting of rental boilers, but they do have a program called the Temporary Replacement Emissions Unit (TREU) which can be utilized when a rental is needed  in a pinch. This program contains an application shield provision which allows renters to install a temporary boiler in place of an existing permitted boiler that is down for repairs without having to get a new permit for the rental boiler. In order to qualify for the TREU Program, the rental boiler being installed must have a heat input equal to or less than the unit it is replacing. Plus, it must not have the potential to produce more emissions than the current permit allows. There is a time limitation to this program; the temporary boiler can be on-site for a maximum of 180 days within a 12-month period.

If you are outside of the two territories listed above, don’t fret! Nationwide Boiler can assist with the permitting process as needed. In addition, utilizing a pre-permitted boiler in a location other than the SCAQMD does have its advantages and can help expedite the permitting process.

With our headquarters being located in California, it is important to us that we are up-to-date with emissions regulations throughout the state. And with other areas of the country starting to experience a similar push for emissions reductions, we have the expertise and experience to help. Nationwide Boiler is proud to take the lead in helping customers everywhere understand and comply with current and future air regulation standards.

Be sure to read Part I of this series to learn about emissions requirements in the SCAQMD.

In the last edition of Boiler Blog 101, we discussed air permitting rules and regulations in the South Coast Air Quality Management District (SCAQMD). In part II, we will cover the basics of air permitting for boilers in another California district that leads the country in air pollution control; the San Joaquin Valley Air Pollution Control District (SJVAPCD).

The SJVAPCD was founded in 1991 with a mission to improve the health and quality of life for all Valley residents through efficient, effective and entrepreneurial air quality management strategies. The SJVAPCD is made up of eight counties in the Central Valley of California; San Joaquin, Stanislaus, Merced, Madera, Fresno, Kings, Tulare, and Kern.

The rules that have been set forth specifically for boilers, steam generators, and process heaters are outlined below:

	QUALIFYING UNITS	NOx LIMIT
Rule 4306	Units Greater Than 5 MMBtu/hr Units Greater Than 20 MMBtu/hr	15 ppm 9 ppm
Rule 4307	Units 2.0 MMBtu/hr to 5.0 MMBtu/hr	30 ppm
Rule 4308	Units 0.075 MMBtu/hr to Less Than 2.0 MMBtu/hr	20 ppm
ADVANCED EMISSION REDUCTION OPTIONS
Rule 4320	Units Greater Than 5 MMBtu/hr Units Greater Than 20 MMBtu/hr	9 ppm 7 ppm
*NOx limits listed are standard options for existing gaseous fuel-fired equipment. Enhanced options as well as limits for new and replacement units will differ. Click each rule to review the full details; certain exemptions may apply.

 

Starting at the beginning of 2019, the SJVAPCD implemented a new rule titled, Best Available Control Technology (BACT). This rule requires that all new permits meet the lowest NOx limits that have been achieved, regardless of what is mandated. In addition, due to Assembly Bill 617, boiler owners in the SJVAPCD are mandated to meet Best Available Retrofit Control Technology (BARCT) for any existing equipment retrofits. This means that when your boiler needs to be upgraded or replaced, it must meet more stringent NOx limits, which can be as low as 7 ppm.

These rules can be overwhelming, which is why Nationwide Boiler’s AQMD experts are capable and ready to assist you with the permitting process needed for your facility. Furthermore, we can help you reduce NOx to comply with your air emissions regulations. Nationwide Boiler’s CataStak™ SCR system is proven to reduce NOx levels to as low as 2.5 ppm. Contact us today for more details.

Stay tuned for Part III, where we will discuss renting boilers in California.