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Nationwide Boiler news and events, industry updates, technical resources and more. You hear it first on The Nationwide Boiler Blog!

A Practical Approach to Easily Decrease NOx, Save Energy, & Improve Your Operations

Our latest case study, highlighting a major food processor is another example of how Nationwide Boiler can help achieve the best performance standards (BPS) for your boilers. We presented a E2Stak solution with a CataStak SCR system and an EconoStak economizer to a food processor in CA to achieve 5 ppm NOx and decease the plant's energy use, which resulted in the customer receiving a rebate check of almost $150,000. Not only did the we help the boilers achieve optimum performance, we also improved the operation and maintenance of the boiler. The plant manager's quote says it all: "This was the first year we could operate the boiler in automatic!"

If you are interested in decreasing your operating costs by saving energy and if you need to comply with tough emission standards, give Nationwide Boiler a call today at 800-227-1966. Our experience and expertise will provide you with additional options you may never have thought possible.

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10 Tips to Improve Boiler Efficiency

The need to operate a boiler efficiently in today's environment and competitive landscape is at the top of many plant owners and operators list. Unfortunately operating a boiler efficiently while meeting local emission regulations do not always go hand in hand. However, advances in boiler system design and low NOx technology solutions have made this a much more achievable task.

The list below includes 10 tips which can instantly improve overall boiler performance and sustainability, helping to achieve more cost-effective maintenance and operations of your steam system.

This list, along with general guidelines for each, will be published in an upcoming issue of Process Heating magazine. Please email Nationwide if you are interested in obtaining a copy.

1.    Reduce Excess Air

2.    Install an Economizer

3.    Install a Condensing Economizer

4.    Upgrade to VFD Fan Controls

5.    Install a Selective Catalytic Reduction System (SCR) with a Standard Low Excess Air/No FGR Burner

6.    Perform Proper Water Treatment

7.    Reduce Boiler Pressure

8.    Consider Boiler Blowdown Heat Recovery

9.    Upgrade to a High Turndown Burner & Controls

10. Implement an Energy Efficiency Program
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Improving Boiler Efficiency

It is important for a boiler to run at its most efficient level in order to avoid costly issues and obtain the best results. Excess air is essential in boiler operation to minimize heat loss and improve combustion efficiency.  Here are some tips to help you make sure your boiler is running at the most efficient level possible:

  1. Periodically monitor flue gas composition and tune your boilers to maintain excess air at optimum levels.

  2. If there is a continuous blowdown system in place, consider installing a heat recovery system.

  3. If there is a non-continuous blowdown system, then consider converting it to a continuous blowdown system coupled with heat recovery.

  4. Reduce operating costs through maximizing the return of hot condensate to the boiler.

  5. If a condensate return system is absent, estimate the cost of a condensate return and treatment system (as necessary) and install one if economically justified.

  6. Repair steam distribution and condensate return system leaks.

  7. Insulate condensate return system piping to conserve heat and protect personnel against burns.

  8. Review your blowdown practices to identify energy saving opportunities.

  9. Examine operating practices for boiler feedwater and blowdown rates developed by the American Society of Mechanical Engineers (ASME). Considerations include operating pressure, steam purity, and deposition control.

  10. Consider an automatic blowdown control system.

Taken from http://www.process-heating.com/Articles/Feature_Article/2afcce64fe4fd010VgnVCM100000f932a8c0____
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Additional Energy Savings with Variable Frequency Drives

Last month on the Boiler Blog, we focused on increased efficiency through the use of O2 trim. This is an easy, cost-effective addition to a boiler system with multiple added benefits. There are, however, additional ways to increase the efficiency of your steam plant even further. A Variable Frequency Drive (VFD) controls a motor’s speed by varying the frequency supplied to it, and VFD’s can help achieve significant electrical power savings when added to your boiler.

To illustrate the benefits of VFDs, take the power usage of the fan. A combustion air fan on a boiler typically uses a large amount of energy. For example, a 125,000 pph boiler can have a fan motor as large as 300 hp. While the actual power usage would typically be less than the rated size of the motor, when operating 24/7/365 at full load and assuming an electricity cost of 8 cents/KW, the cost of electricity can be upwards of $150,000 - just for the combustion air fan! 

The use of VFDs will provide the most savings for boilers that have an average annual operational load of less than 100%. In fact, if your average boiler load throughout the year is 50%, or half load, you could save ⅞ th the fan power. This means that with the use of a VFD, the fan would require a fraction of the typical amount of energy used when running your boiler at full load. Generally speaking, if your boiler is operating at half load the fan will also operate at half speed.  According to the fan laws, fan power is related to change in fan speed to the 3rd power.  When operating the fan at half speed, the change in power is (½)3 or 1/8th the power!  This is where the power savings would come from and why it would be most beneficial to utilize a VFD for scenarios where the boiler system operates more consistently at half load.

Let’s look further into the reason behind using 50% fan speed for 50% boiler load. When running your boiler at half load, the air flow requirement will also be reduced by half (assuming the burner excess air stays the same).  Since the fan laws state that air flow changes linearly with fan speed, that means that at 50% fan speed (or RPM), the flow would be 50% of full load.  For the static pressure requirement, the fan pressure is closely related to the square of the change in boiler load.  So, at 50% load, the static pressure change would be (½)2 which also matches the fan laws which state change in fan speed changes fan static by the square.  You’ll notice that if you multiply the flow and static changes together (i.e. ½ * (½)2) you get ⅛ th which is the same number for the power savings.

If a VFD is not being used, the alternate device is likely a line motor starter. With a motor starter, the fan is always running at full speed. At 50% load, the air flow is about half but the static pressure requirement typically increases due to the closing of the air dampers (which are used instead of a VFD to control the flow).  That said, with a standard motor started, the overall fan power requirement stays about the same regardless of whether the boiler is operating at half or full load.

Stay tuned for our next Boiler Blog for additional educational topics, Nationwide Boiler news, and more!

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