Boiler Blog | Nationwide Boiler Inc.

Nationwide Boiler is known as being an innovative leader in the rental boiler industry. Over fifty years ago we pioneered the mounting of a 24,000 lb/hr package watertube boiler to a highway-legal trailer, and followed with many other firsts including the world’s largest trailer-mounted saturated and superheated steam boilers (125,000 lb/hr and 110,000 lb/hr, respectively).

In this age of digital technology and pandemic isolation requirements, Nationwide Boiler’s control division, Pacific Combustion Engineering, realized the need for virtual factory acceptance testing (FAT). An FAT is an essential element of the testing and acceptance of new critical control systems. The main goal of this test is to prove and certify performance built for a specific application and ensure all design requirements are attained.

Pacific Combustion’s new test gear consists of a 19” HMI that replaces toggle switches, indicating lights, potentiometers, and analog gauges. A PLC drives relays and consists of contacts that can be configured for the voltage that is required for input simulation. Outputs are displayed via selectable 120vac and 24vdc terminals. Analog 4-20ma inputs are selectable as either loop or self-powered.

During the virtual FAT, a web portal is accessible by the client through an audio/video link to the testing, and the client can actually operate the test rig HMI screen from their location. Links are also furnished to the burner management / combustion control system PLC and HMI.

This is a truly unique innovation at a time where travel can be difficult, providing an alternative to the traditional FAT and allowing business to continue even in heightened times like a global pandemic.

For more details on our virtual FATs, be sure to check out our upcoming feature in Process Heating Magazine. We will post the direct link as soon as it's available. And be sure to give Pacific Combustion Engineering a call to assist with your next control system upgrade. 360-335-1443

It's that time of year again for our annual freeze protection reminders. As you know, winter can bring extremely cold weather conditions, especially in Canada, the Northeast, Midwest, and Upper Midwest. To reiterate what we have been saying for years, here are a few things to consider to protect your rental boiler and auxiliary equipment (deaerators, water softeners, etc.) from damage due to freezing temperatures this winter.

1. If you are renting a trailer or skid-mounted firetube or watertube boiler and installing the unit outdoors, these systems are completely exposed to the environment. User's should consider enclosing the front and/or the rear end of the boiler, or build a temporary enclosure around the entire system. An external heating source should also be used. 

2. Install the proper heat tracing (steam or electric) and insulation on all main lines and piping components, regardless of whether the boiler (or auxiliary equipment) is in operation or sitting as stand-by. This should include the following lines: 
      - Sensing lines for all transmitters
      - Primary and auxiliary low-water cut-offs
      - Water column and connected piping
      - Bottom blowdown and surface blow-off piping, depending on the length of the piping runs. These valves should also be left open. 

Tomato season is here, and we already have a 70,000 lb/hr, 400 psi design trailer-mounted rental boiler on location at one of our customer sites to support peak season steam demand. This boiler is rented annually in the Central Valley of California for three to four months during the tomato processor’s short but critical production season. To meet the requirement of 5 ppm NOx, the boiler is supplied with an ultra-low NOx CataStak SCR System. This solution allows the facility to operate their own boilers without overworking them, while complying with local air regulations and satisfying seasonal demand.

Some years ago, the company identified a bottleneck in its evaporation system that hindered peak production capacities. The bottleneck was easily resolved; however, it would take more steam to fully realize the increase in production. Although the existing boilers were capable of running the newly found evaporation capacity, the increased production required the existing boilers to operate at 100% output continuously, leaving no room for margin and no buffer against any process anomalies. After evaluating the cost of investing in a new boiler, the detrimental effects of operating the existing boilers at 100 percent output, and the process vulnerabilities of having no excess steam capacity, the decision was made to rent a supplementary steam boiler on an annual basis.  

Many industries face periods of increased process steam requirements and to satisfy demand, steam can be supplemented with a temporary rental boiler. This practical solution allows facilities to maximize the resources needed to meet current, short-term and long-term steam needs. A short-term or long-term rental solution can save time, conserve capital, minimize risk and maximize available resources.

Check out our past article from Today’s Boiler Magazine to learn more about how temporary boilers can support seasonal steam demand, and contact us today if a rental boiler may be the solution to your peak season needs!

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 3^rd power.  When operating the fan at half speed, the change in power is (½)³ or ¹/₈^th 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!