Boiler Blog Archive | Nationwide Boiler Inc.

Selecting the right boiler for your facility is more than just a design choice – it directly impacts efficiency, reliability, operating costs, and emissions compliance. Among the most common designs are firetube boilers and watertube boilers, each with unique advantages depending on the application. These boilers can also be classified by pressure (low or high), output (steam or hot water), and steam temperature (saturated or superheated), adding further considerations to the decision-making process.

The following overview outlines the key differences between firetube and watertube boilers to help facility managers, engineers, and plant operators choose the system that best fits their needs.

What is a Firetube Boiler?

A firetube boiler, also known as Scotch Marine boiler, is one of the most traditional and widely used boiler designs. In this system, a large pressure vessel holds water, and tubes carrying hot combustion gases run through the vessel. As the gases pass through these tubes, heat is transferred to the surrounding water, gradually increasing its temperature until it produces either hot water or steam depending on the application. Because the “fire” or combustion gases are inside the tubes, the design is known as a firetube boiler.

Key Advantages:

With over 30 years of experience, our General Manager at Pacific Combustion Engineering, Jack Valentine, is an expert when it comes to the design of combustion control systems. In the Winter 2021 edition of Today’s Boiler, Jack discusses the features and options typical of Combustion Control Systems today. Let’s take a peek at what he had to say.

Combustion equipment safety is essential for the daily operation of facilities and safety of plant personnel. Safety protocols and mechanisms in industrial plants have improved drastically in the last century, but incidents still occur far too frequently. Because boiler systems are inherently dangerous, safety must be factored into the design of not just the boiler, but also the burner, combustion control, and the overall operation of the system.  

The Combustion Control System (CCS) on a boiler, also known as the Boiler Control System (BCS), refers to the set of instrumentation and controls that modulates the firing rate of the burner in response to load demand while maintaining the proper air/fuel ratio (AFR). It works in conjunction with the Burner Management System (BMS) that provides safeguards before, during the initial light-off of the burner, and at shutdown. The BMS also provides the flame safeties and interlocks required to keep the boiler safe during continuous operation. Depending upon the complexity of the boiler, the CCS can also provide other functions such as drum level control and draft control.  With Low NOx burners, it also controls the proper amount of flue gas recirculation (FGR) to the burner.

For the sake of simplicity, the various types of CCS described below will be for boilers firing a single fuel gas only; fuel oil and solid fuel systems add an entirely new level of complexity.

Boilers are designed to produce steam to accomplish a multitude of tasks; from powering a plant to sterilizing hospital equipment. In simple terms, a boiler is a closed container in which water is heated to its boiling point to produce usable steam. In order to produce steam, there are two key items that must be involved: water and heat.

A boiler is comprised of two seperate systems: the steam-water system (waterside), and the fuel-air-flue system (fireside). As you might have guessed, water is first introduced into the waterside of the boiler. Alternatively, the fireside of the boiler provides heat, produced through the combustion of fuel (commonly natural gas or fuel oil, but can be another source) and air, which is controlled by the burner.  The heat that is created within the fireside is transferred to the waterside to produce steam.

To complete a boiler system, additional elements are required. This typically includes the following major components:

•  Burner: a mechanical device that supplies the required fuel and air for proper combustion.
•  Controls: the BMS (burner management system) protects the equipment and personnel from safety issues.
      The CCS (combustion control system) controls the air and fuel for proper combustion.
•  Fan: supplies air for the combustion to take place.
•  Water Softener: pre-treats the boiler feedwater for removal of hardness, which would otherwise cause detrimental scale
   inside the boiler system.
•  Deaerator / Feedwater System: removes oxygen and gases from boiler feedwater supply (which will also damage boiler
  internals), and feeds it to the boiler system via high pressure feedwater pumps.

All of these elements come together to create a robust steam supply system that is utilized in an abundance of processes throughout many different industries. Boilers truly are a work of art, with many pieces working as one system to make something extremely powerful and impactful, which is why we at Nationwide Boiler are so passionate about what we do.

Stay tuned for the next article in ur Boiler Basics 101 series to learn more about common types of boiler systems.  

When selecting an industrial steam boiler, it’s essential to understand the key differences between saturated steam and superheated steam boilers. These two steam classifications play distinct roles across industries, ranging from heating processes to power generation. In this guide, we’ll explore the science behind saturated and superheated steam, advantages and disadvantages of each, and how to determine which type of boiler is best suited for your application.

What Is the Difference Between Saturated Steam and Superheated Steam?

Saturated steam is steam that exists at the boiling point of water and is in equilibrium with liquid water at a given pressure and temperature. It contains moisture and is often referred to as “wet steam.” Saturated steam is produced when water is heated until it begins to vaporize.

Superheated steam, on the other hand, is created by heating saturated steam beyond the boiling point without increasing pressure. Also known as “dry steam,” superheated steam has no moisture content, a lower density, and higher energy content. It remains in a gaseous state even as it cools, which makes it highly effective in certain mechanical and thermodynamic applications.

Common Industries and Applications for Each Steam Type