Burner Tuning: Best Practices for Achieving the Perfect Air-to-Fuel Ratio

Fuel-fired heating equipment is something all facilities depend on. So, it’s essential your facility is getting the most out of your burners. What if there was a way to make your burner more efficient, while also cutting down on energy costs? Good news: There is. With the right adjustments to the burner’s air-to-fuel ratio, your system can work much more efficiently, and cost you less to operate.

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What Is the Air-To-Fuel Ratio?

The first step to understanding how to cut down on burner energy costs is to understand what an air-to-fuel ratio is. Simply put, an air-to-fuel ratio is the measure of air compared to fuel involved in the combustion process.

For safety reasons, knowing what the air-to-fuel ratio curve is on your burner system is critical. This curve measures the lowest amount of excess air that can be in the flue gas without producing carbon monoxide. Every burner has a curve like this, and understanding yours is paramount to your team’s safety.

Run Your Burner at Optimal Efficiency

To operate your burner at peak efficiency, you need to know what the best excess air percentage for your burner is. There are a couple of factors to consider when calculating this, such as:

  • What solvents your burner operates on
  • How much carbon monoxide your burner produces

To prevent carbon monoxide emissions and soot forming on your heating equipment, run your burner at approximately 10-20% excess air at high fire. Even with many burners being made and run differently, running your burner somewhere within this range should work for your system (this is another reason to know your air-to-fuel ratio curve).

Make sure to be careful when adjusting the amount of excess air. Too much or too little can hurt the efficiency of your burner. Reducing excess air, in general, will reduce the stack temperature, which increases combustion and boiler efficiency, but this doesn’t mean you should completely reduce the amount of excess air. If you cut too much out, you could find yourself in a bad situation.

In some cases, reducing too much excess air could cause potentially dangerous reactions. If you’re using flammable solvents in your burner, you must be sure you’re using enough excess air to dilute the solvents. Not only does this ensure adequate drying rates and carries vapors out of the burner, but it also keeps the process moving along at a good pace and eliminates the risk of an explosion.

What Affects Excess Air Levels?

Excess air levels can be affected by different factors — for example, high fire and low fire. Every burner will be different, which is a primary factor concerning fire levels. With the differences in each burner, it makes sense that each separate system has different high and low fire levels.

These factors make it sound like it’s challenging to keep track of excess air level changes, but it isn’t. If you can take a measure of oxygen and combustibles in the flue gases, you’re set.

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Measuring Air-Fuel Ratios

There are two main ways to measure air-fuel ratios. The first is by analyzing the flue gas for levels of oxygen and combustibles. It’s best practice that you measure oxygen in percentages since carbon monoxide gets measured in parts per million (or PPM for short). In most cases, equipment that measures oxygen is better than equipment that measures carbon dioxide, as they tend to be more accurate.

If you’re having trouble accurately measuring excess air levels or tuning your burner, hiring a professional is a wise choice. On average, a plant that employs a qualified combustion vendor saves more than 2.2% of fuel costs.

Once you’ve considered all of the different factors in measuring air-fuel ratios, you can accurately calculate your potential savings.

Tips For Cutting Costs on Your Heating System

There are certainly more ways to reduce your burner’s energy costs other than managing your air-to-fuel ratio. Here are a few additional tips to further cut costs:

  • Operate burners at, or close to, design capacity
  • Reduce excess air used for combustion
  • Clean heat transfer surfaces
  • Reduce radiation losses from openings
  • Use proper burner insulation to reduce wall-heat losses
  • Adequately insulate air or water-cooled surfaces exposed to the oven and steam lines leaving the burner
  • Install heat-recovery equipment
  • Improve water treatment to minimize burner blowdown
  • Repair steam leaks
  • Minimize vented steam
  • Implement a steam-trap maintenance program
  • Utilize a back-pressure turbine instead of pressure-reducing or release valves
  • Minimize air leakage into the burner by sealing openings
  • Maintain proper and slightly positive burner pressure
  • Recover part of the burner exhaust heat for use in lower-temperature processes

It may seem like a lot of information to keep track of, but it will help your burners run efficiently, saving you money. When it comes to optimizing heating equipment, RasMech is there to ensure your heating equipment runs efficiently and saves you money. As always, follow your manufacturer’s recommendations and be sure to have adjustments made by a professional. If you’re unsure about your burner, feel free to contact our experts and schedule a consultation to ensure you are operating at maximum efficiency.

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