As a boiler service company, we know old boiler systems with outdated, inefficient equipment are the norm for our industry. This is because boiler technology is mainly stable, and boilers are reliable pieces of equipment that can last decades. They are also expensive.
Low NOx Burner Emissions are Now the Norm
Federal air quality laws and rules that apply to industrial boilers allow states to set local standards that are more stringent than the federal standard to achieve acceptable ambient air quality. In some areas, boiler operators must meet the “Ultra-Low NOx” (ULN) requirements, typically less than 10-12 ppm. This was first done in California. Today’s ultra-low NOx burner use technology to lower NOx emissions. Low NOx burners are constructed to control air and fuel mixing at each jet. And significantly less NOx is formed in the process.
Why Retro Burner Replacement is Practical
When adding new parts, kits, and technology to a boiler, the goal is to increase the efficiency of a system. Recent innovations and design improvements allow an older boiler to expand its capability. Since most boilers only operate at around 60%, replacing or retrofitting an older boiler could equal substantial cost savings for a facility.
A boiler can consume almost four times its cost every year in energy. So enhanced function of a new or retrofitted boiler saves fuel and improves the quality of overall output. And a boiler that has been retrofitted reduces the emission of carbon and other pollutants into the air. Many outdated systems are, or soon will be, prohibitively expensive to run and out of compliance with air quality management district, state, and federal regulations.
The Science Bit
There are three primary ways a boiler can form NOx: rapid formation, thermal formation, and fuel formation. Rapid NOx contributes negligibly to combustion emissions, so thermal and fuel NOx are the primary target. Thermal NOx is produced during combustion and is a reaction between oxygen and the air’s nitrogen. Fuel NOx is the result of bound nitrogen in the fuel source that is freed during combustion. Since thermal NOx is highly reliant on combustion temperature and oxygen presence, reducing the peak flame temperature and excess oxygen are the best ways to control it. Low NOx burners commonly achieve this by either flue gas recirculation or a lean premix of fuel and air. Flue gas recirculation (FGR) recirculates exhaust gases back into the combustion chamber. Because flue gas is both cooler and has substantially reduced oxygen concentrations, this can dramatically reduce NOx concentration in emissions.
Retrofit
Shifting to a low-NOx burner with configurable NOx emissions prepares your system for strengthening NOx regulations without incurring an unnecessary efficiency blow in the meantime. For the genuinely forward-looking, switching to alternative fuels like digester gas and landfill gas can make beneficial use of these often wasted fuel sources. If you have any questions about retrofitting your boilers, don’t hesitate to give us a call or request a consultation.