With so many variations in applications and increased complexity of processes, selecting the proper burner for a heat processing application can be a challenge. Careful burner selection, however, can prevent downtime and help your company save money.
Selecting the proper burner for a particular application takes practice, and quite a few variables should be considered to ensure proper burner operation. Some are simple, but others take a bit more input. What follows are the key points to help you when it is time to select your next burner.
1. Calculate Capacity
Also known as burner rating, burner capacity is defined as the range between the minimum and maximum BTUs that can be released from a burner with a stable flame and acceptable combustion. In other words, burner capacity is the minimum and maximum firing ranges.
When selecting a burner, make sure that any models you consider have adequate capacity for the specific process. Too little capacity can lead to a smaller workload and prevent the combustion system from reaching the required temperature. This can lead to downtime in production, which directly affects a company’s financials. Too much capacity and it could mean overkill for an application, meaning you are paying for a burner yet not using it to the capacity level it was designed for.
Understanding the capacity requirements and ensuring the burner can meet them will help prevent issues with production.
2. Take Turndown into Account
Like burner capacity, it is important to understand what turndown performance is needed for a particular process. Burner turndown is the ratio of maximum capacity to the minimum capacity. As an example, suppose you have a burner that has a maximum capacity of 5 million BTU/hr and a minimum capacity of 100,000 BTU/hr. This would mean that your turndown ratio is 50:1.
Turndown is an indicator a burner’s ability to handle various load sizes. The turndown for a burner must be equal to or larger than the turndown that is required for a particular application. Although the turndown required for most applications is not large, it still is an important thing to factor in when selecting a burner. Not having enough turndown can cause problems and damage to the process.
3. Tote Up Temperature Needs
The third area of consideration during burner selection is the temperature of the process. It is important that the selected burner has temperature performance to meet the needs of the application. At a high level, burners are divided into two categories: high temperature and low temperature. Low temperature burners operate primarily below 1000°F (538°C).
4. Ponder Process Details
Beyond temperature and the burner itself, it also is important to understand the details of the process and what the specific requirements are. For instance, if the situation warranted an indirect fire method, one easy way to achieve this is to fire into a tube. Tube firing is not possible with every burner, which is why it is important to know the process details. They can be a key factor in burner choice.
5. Figure Out Flame Geometry
When selecting a burner, ensure that burner has the proper flame geometry to fit a specific chamber. For example, too long of a flame can cause flame impingement. The burner manual can help you determine the proper geometry.
In addition, when firing into a chamber, it is important to be aware of backpressure and cross velocities. Backpressures can affect overall burner operation. Too much backpressure can stop gas or air flows to a burner. Cross velocity causes issues with lighting and flame stability, but it can be prevented by using a secondary sleeve.
6. Master Mounting
One of the most obvious but often overlooked areas of proper burner operation and maintenance is mounting. Two types include wall-mount and in-duct burners.
- Wall-mounted burners are easier to access, allowing for easier maintenance. However, wall-mounted burners tend to be impacted by cross velocities.
- n-duct burners are enclosed in the duct, which means they are more difficult to access. However, they are better suited to handle the cross-velocity issues associated with wall-mounted burners.
The specific application will help determine the type of mounting required.
7. Investigate Ignition
Ignition is another point of consideration that seems obvious, but it is often overlooked. Burners can be lit by either pilot or direct spark. Some burners allow for both methods, but like many other instances, the application itself will dictate which method is best.
In conclusion, a number of special considerations should be kept in mind when selecting a burner. Aside from the burner characteristics outlined, other factors that influence burner selection are applicable national and international codes and standards, available fuel type, emissions requirements and area rating (for example, hazardous duty). Some considerations are clearly listed in the product instructions. Others might not be so obvious or are more in depth.
Likewise, processes can be complex, particularly if a number of special conditions apply. Never hesitate to consult with a burner expert to ensure that the right decision is made.