Boiler Blog | Nationwide Boiler Inc.

Nationwide Environmental Solutions is a division of Nationwide Boiler, formed over a decade ago to provide emissions and efficiency solutions to our wide range of customers. In today's day and age, protecting the environment and reducing the production of greenhouse gases is more important than ever, which is why we are so proud to have a product that exceeds expectations time and time again. 

Most recently, we teamed up with MDH Boiler Serviced to supply a food processing facility in Southern California with a new burner and CataStak SCR system retrofit for their existing 475 hp firetube boiler. With lower than typical exhaust temperatures for an SCR application, a more robust system was designed to ensure adequate performance. We are happy to report that the system not only met the guarantee of 5 ppm NOx, but actually exceeded expectations and tested at just 1 ppm NOx and 1 ppm ammonia slip! Exciting news for the team, solidifying future orders that will support the end-user efforts in reducing their company's overall greenhouse gas emissions. Check out our latest press release for the full story.

If your facility is under an air district mandate to reduce the NOx and/or CO output from your boiler or other fired equipment, give us a call at 1-800-227-1966 to learn how we can help.

When offline, boilers can still be at risk of accumulating corrosion and deterioration that decreases the useful life of a boiler and increases maintenance and repair costs. With proper planning and preparation, a boiler can be taken offline safely with a procedure known as boiler lay up. There are two specific ways to properly shut down your boiler: dry lay up or wet lay up.

Dry lay up is a procedure that involves removing all water and moisture from the boiler. The main advantage of a dry lay up is that you can basically “set it and forget it”. There are no chemical, equipment, or fuel costs. Once completed, the boiler will just need to be checked occasionally to ensure moisture is not getting back into the boiler. A dry lay up is best for extended periods of shutdown. If the system will need to be put back online on short notice or remain in standby, this procedure would not be suitable.

A typical dry lay up procedure involves the following steps:

1.  Perform a lock-out and tag-out and isolate the boiler from the steam system.
2.  Perform column and bottom blowdowns and drain the boiler completely. 
3.  Open the fireside and remove any soot from the tubes. Look for rust or scale on the pressure boundary wall, and further evaluate any   leakage. Inspect refractory and insulation.
4.  Open the waterside and look for signs of gasket leakage and corrosion of the gasket seating surface. Inspect the entire waterside   and evaluate any scale and corrosion.
     - Any scale left on the waterside can trap moisture and oxygen and corrode the boiler further, so remove as much scale as possible.
5.  Dry all surfaces with a fan or electric air heater.
6.  Have a certified boiler inspector perform a thorough examination of all surfaces, internal and external.
7.  Determine if any repairs are required - this may be the ideal time to perform repairs without any incurring downtime, since you are   already preparing for an extended offline period.
8.  Coat the fireside with mineral oil, let it dry and close all openings including the stack. A moisture-absorbing material like silica gel or lime. 

A wet lay up is performed when the boiler is idle in standby; it is still full of water but isolated from the steam system while the burner remains offline. The procedure involves chemically treating the water to protect the metal surfaces of the boiler and is  the ideal lay up method when a boiler might need to be fired on short notice. It does, however, require additional monitoring and treatment costs that aren’t required for a dry lay up.

A typical wet lay up procedure is very similar to a dry lay up, however, the fireside should not be swabbed with mineral oil.

1.  Follow steps 1-7 above.
2.  Fill the boiler with the chemically treated hot water (greater than 180F) to its normal operating level. Allow air to continue to vent until  the boiler is full or until the steam boiler is at its normal operating level and warm.
3. Once complete, boiler water should be circulated periodically to prevent stratification of chemicals. Chemical concentrations should also be monitored routinely.

Before starting a steam boiler in wet lay-up, blow down the boiler to reduce alkalinity, ensure that all tags and locks are removed, and be sure to witness a minimum of three steam cycles before allowing the boiler to run in automatic. This will help ensure proper operation after bringing a system back online from a wet lay up.

If your facility falls under a temporary business closure mandate due to the current state of the COVID-19 pandemic, it is imperative that you follow one of the procedures outlined above to properly shut down your boiler system. View this technical article provided by the National Board for more detailed information on these two types of boiler lay up procedures.

Deaeration of boiler feed water is primarily known to remove dissolved oxygen from the water, however, there are four additional advantages of utilizing a deaerator: (1) carbon dioxide removal, (2) improved operation, (3) improved heat transfer, and (4) energy savings. In this month’s edition of Boiler Basics 101, we review the importance of including deaerators as part of your boiler plant.

Corrosion in boilers from dissolved gases leads to reduced heat transfer and efficiency losses. Both oxygen and carbon dioxide, if not removed from the water entering a boiler, will cause corrosion. Dissolved oxygen will attach to the metallic components of a steam system and form oxides, or rust, on boiler heat transfer surfaces. If carbon dioxide is present with the oxygen, the two gases together can be up to 40 percent more corrosive than if they were acting individually. Removing non-condensable gases and limiting or avoiding corrosion will greatly improve heat transfer.

Deaerators also serve the purpose of pre-heating the water before it enters the boiler. This process saves energy by recovering flash and exhaust steam from plant returns, energy that would normally be lost to the atmosphere, and utilizing it to pre-heat the feedwater. This recovered steam can account for 20 percent of the fuel typically required to provide heat for that process. Pre-heating the feedwater will also greatly reduce the chance of thermal shock caused by the expansion and contraction of heating surfaces and will ultimately improve the operation of your boiler.

Deaerators and atmospheric feedwater systems both have the same purpose and are made up of several individual devices including feed pumps, a corrosion resistant receiver tank, and a control panel. A deaerator does its job by mixing steam with soft water inside a pressurized tank, removing oxygen molecules which are then vented into the atmosphere. Atmospheric feedwater systems are non-pressurized and perform the same function while operating at a lower (atmospheric) pressure. A notable disadvantage of operating at a lower pressure is that a lesser amount of dissolved gases are removed. Although atmospheric systems are more cost effective, process requirements will dictate which system is ideal for your application.

Overall, if boiler feed water is not properly deaerated, corrosion will occur, and a boiler will operate less efficiently with a higher possibility of facing costly downtime and boiler repairs. Nationwide Boiler provides new deaerators and maintains a rental fleet of deaerating boiler feedwater systems for both low and high pressure applications. Our systems range in size for boilers 24,000 to 225,000 lb/hr, and are configured one of two ways: a skid-mounted deaerator with feed pump stand or complete mobile feedwater system including the deaerator, feed water pumps, water softener, and chemical feed system, all pre-piped and wired and installed inside of a trailer-mounted van.  

Be sure to check out our previous Boiler Basics 101 blogs and stay tuned for the next edition!