A large number of industrial and commercial boilers used today have been in operation for more than 20 years. If your boiler package has been in place for 20 years, it’s most likely operating at 60-70% efficiency, using large amounts of fuel as well as costing you a lot of money to keep it running and in good condition. With a sluggish economy and rising energy costs, operating a boiler that’s not fully efficient is unacceptable.
While replacing your old boiler with a new one can easily fix the problem, many businesses are not ready to spend a lot of money on boiler replacement. Boiler replacement cost can range from at least $100,000 and above, making it a challenge for most facilities and plants that rely on boiler systems. The best option in such cases is to consider boiler upgrades or retrofits. Upgrades can be done on an existing boiler and significantly reduce fuel usage, increase efficiency, and reduce NOx emissions.
If your existing boiler package is in good condition, there are various upgrades you can opt for to cut fuel use, reduce energy costs, and learn how to measure boiler efficiency. These upgrades revolve around:
- Burner components
- Burner combustion controls
Replacing a Burner
Burners are the true drivers of boiler costs. After prolonged use, your boiler burner will not be as efficient as expected. With wear-and-tear on moving parts, linkage joints, and other parts, your burner will no longer be able to keep tight control of its air-to-fuel ratio degrades. Compromised by age, your burner will experience what’s known as hysteresis. When this happens, your burner can no longer maintain the desired air levels across the entire firing range needed to ensure optimum combustion. Despite high boiler replacement cost, a replacement is the best option.
Higher excess air often leads to lower burner combustion efficiency. Additionally, further deterioration of key burner components that ensure proper air-fuel mixing can cause further problems. Most of these problems result in unburned fuel and high excess-air levels leading to low performance, burner efficiency reduction, and unnecessary spending. It’s important to note that if a burner is too old or has many worn out parts, a new replacement that features lower excess air requirements, higher turndown, and advanced controls might be the better option.
In most cases, replacing a burner can help achieve 5-10% fuel reduction in savings, a significant move, despite the high boiler replacement cost. You should also note that old burners are not up to date with the latest EPA (Environmental Protection Agency) regulations. If you’re still using a legacy burner, you are more likely to pay hefty penalties for violating emissions standards. Replacing your outdated burner with a newer model will help you meet compliance requirements.
Proper Burner Integration
When replacing a new or retrofitted burner, proper integration is critical. It not only ensures optimal control to meet the demands of your plant or facility, but also the integration of advanced control, communication, and building management systems. If proper integration is done, burner upgrades can achieve sustainable 15-20% energy savings over time.
Considering that boiler systems comprise of different equipment and parts from different manufacturers, it’s important that everything works together to achieve maximum efficiency, ensure better management, and understand how to measure boiler efficiency. Understanding what installations are required, what upgrades will work, and what technology suits your boiler burner requires expertise and helps avoid potential boiler replacement cost. Ensure that only qualified and highly experienced boiler technicians and combustion control engineers handle the burner integration process and upgrades.
Burners must be properly matched with boilers with more focus on the characteristics of the burner’s flame, as well as the burner’s combustion. Considering that most burners are not custom designed for specific applications, a burner must be flexible enough to handle variations in the combustion process without affecting operation. Heavy duty construction is also necessary to reduce high and low-frequency vibrations at certain loads.
One of the best burner upgrades available is replacing your legacy burner with a new one that incorporates High Turndown (HTD) capability. Burners with high turndown are able to continue operating even at lower firing rates to meet lower loads. With greater HTD capability, a burner experiences fewer cycles. Burners must perform automatically controlled pre-purge and post-purge sequences to reduce cycling occurrences that affect burner pressure, hot water temperature and proper fuel combustion.
During these pre-purging and post-purging sequences, the burner must raise water temperature or fluid to be heated to make up for any heat loss. During this process, the fan motor has to be activated, further increasing energy costs on top of the upgrades or boiler replacement cost. High turndown burners help reduce these cycling occurrences and related costs significantly. Fewer cycles also mean less waste and fatigue for your burner, leading to savings in regular maintenance costs.
Upgrading to parallel-positioning burner systems is a great option when you’re looking to improve burner efficiency, save operational and maintenance costs, and know how to measure boiler efficiency. Traditional burner controls use single-point positioning that is not efficient in air-to-fuel ratio control. Parallel positioning control drives fuel, air and sometimes low NOx FGR (flue gas recirculation) metering valves independently through a pre-programmed control system to achieve the desired air-to-fuel ratio in the firing range, therefore achieving proper oxidation.
Parallel positioning motors are accurate in providing optimal conditions for air-fuel FGR that match the capability and load conditions of the burner. Ensuring minimum excess air throughout the firing range is crucial to achieving burner combustion efficiency, which in turn reduces fuel combustion by up to 5%. Combining parallel positioning control systems with O2 trim systems helps further manage excess-air levels more precisely.
O2 trim systems come with sensors that measure and control environmental conditions that can drive excess-air levels high or down during burner operation. They make a huge difference, especially when you want to avoid high boiler replacement cost. When properly utilized in combination with parallel position control systems, this feature improves fuel utilization by 5%.
You can also improve burner combustion efficiency by adding a variable speed drive (VSD) or a variable frequency drive (VFD). With older burner systems, combustion air or motors are usually set to operate at a constant speed, regardless of low or high system load. Air-flow rates are metered by dampers which lack efficiency in regulating energy use depending on system load. That means that even with the heating load at 30%, the electrical load on blower motors may range 70% or even more.
When VSD or VFD is incorporated in a burner system, significant electricity savings are achieved, often paying for the system upgrade in less than two years. When VSDs are added, the system is able to operate at lower fan speeds, meaning quieter operation is also achieved. In addition to this, they also ensure less stress on moving parts, therefore, decreasing system maintenance costs. Adding VSD to your burner will help you save boiler replacement cost.
Microprocessor Based Controls
Microprocessor based controls are a great addition to complex systems that include multiple boilers or burners. Instead of sizing each boiler to handle full load requirements, you should opt to use multiple boilers that can be modulated to meet part of the load as required. This is successfully achieved by adding microprocessor-based controls that help modulate boiler loads automatically. Automated boiler sequencing reduces energy use and minimizes wear-and-tear associated with cycling on boilers and burner components.
Making the Most of Your Investment
While burner upgrades come with huge savings over time, it’s important to inspect and maintain your burner and boiler components regularly. Let Manley’s Boiler, Inc. help your business with regular maintenance, ensuring an optimal air-to-fuel ratio throughout your boiler’s equipment life and firing range. These improvements will go a long way into helping you understand how to measure boiler efficiency and correctly estimate the savings made from your burner upgrades. Contact our expert team today!