What Is Simple Vertical Boiler?- Parts, And Working

What is a Simple Vertical Boiler?

A simple vertical boiler is designed with its main axis standing upright, perpendicular to the ground. This orientation sets it apart from the more common horizontal boilers. Depending on its construction, a vertical boiler can be either a fire-tube or a water-tube type.

You’ll find vertical boilers in all sorts of early steam-powered applications—think about the first steam locomotives and various mobile machines where compactness and ease of installation were important.

Let’s break down its structure: the heart of the boiler is a tall, cylindrical shell, which is surrounded by a vertical firebox. Interestingly, the firebox itself is usually a bit narrower at the top, making it easier for steam to rise and collect. Right at the bottom of the firebox sits the grate, where fuel is burned.

Inside, you’ll typically notice two or more cross tubes set at an angle. These aren’t just there for show—they significantly boost the heating surface, which helps with both heat transfer and water circulation. That’s an old-school engineering trick to get more efficiency out of a simple design.

Steam escapes naturally through a stack at the top of the firebox, creating what’s called a natural draught. For practical reasons, there are hand holes at the ends of the cross tubes—these little openings make cleaning much less of a chore.

On top of the shell, there’s a manhole, which is exactly what it sounds like: an access point big enough for someone to climb inside for cleaning or maintenance. Down at the very bottom, you’ll spot a mud hole, which is handy for draining out sediment that settles over time. The area between the firebox and the outer shell is where the water sits and gets heated.

To keep an eye on things, a tubular gauge glass shows the water level at a glance. And, of course, safety comes first—a pressure gauge, a safety valve, an air vent valve, and steam supply valves are all fitted at the top of the crown plate to help operators manage and monitor the boiler’s performance.

Parts of a Simple Vertical Boiler

• Vertical Cylindrical Shell: Think of this as the main body of the boiler—the big, upright cylinder you notice first. Almost all the water sits inside this shell, and there’s a section up top reserved just for steam. Every other part of the boiler is tucked inside this outer shell.
• Cross Tubes Inside the shell, you’ll find one or more cross tubes. These are riveted or flanged into place. Their main job? They boost the heating area and help the water circulate better, making the boiler more efficient.
• Furnace (or Firebox): This is where the magic (or really, the burning) happens. Coal goes into the furnace and burns here, producing all the heat needed to turn water into steam.
• Grate: Look at the bottom of the furnace and you’ll see the grate. This is basically a platform where the coal sits as it burns.
• Fire Door (or Fire Hole): You can’t burn coal without a way to get it inside, right? That’s what the fire door or fire hole is for—it’s the opening through which coal is fed into the furnace.
• Ashpit: Once coal burns, it leaves ash behind. The ashpit is designed to catch and collect all that leftover ash so it doesn’t clog up the furnace.
• Hand Holes: Maintenance matters, so there are hand holes opposite each cross tube. These are there so someone can reach in and clean the cross tubes when needed.
• Chimney: Finally, there’s the chimney—a tall, vertical pipe that runs from the top of the firebox up through the shell. Its job is to vent out smoke from the burning coal, sending it safely up and out into the atmosphere.

How does Simple Vertical Boiler Work?

In a basic vertical boiler, the process starts when fuel is fed through the fire hole and onto the grate, where it burns to create hot gases. As the fuel burns, it eventually turns to ash, which then falls down into the ash pit below for collection.

Typically, these boilers have a diameter ranging between 3 feet 9 inches and 5 feet, with an overall height of about 9 feet. Each cross tube found inside has a diameter of 9 inches.

Looking at the main figures, the boiler provides around 80 square feet of heating surface, while the grate area is approximately 8.4 square feet. The system is designed to operate at a pressure of 100 PSI.

As for the movement of gases, the hot combustion gases produced in the furnace flow around the boiler’s tubes before making their way out to the atmosphere via the chimney.

The heating process relies on natural circulation within the water. As the water absorbs heat, steam begins to form and gathers in the steam space located at the top of the boiler. This steam is stored there until the pressure reaches the desired level, at which point it can be drawn off and used—for instance, to power a turbine or an engine.

Application of simple vertical boiler

• The simple vertical boiler finds widespread use in railway locomotives—for instance, it’s the main type seen in traditional railway steam engines.
• You’ll also come across simple vertical boilers powering road vehicles, particularly classic steam wagons and lorries.
• Another notable application is in steam tractors, where the simple vertical boiler has long been a familiar sight.
• When it comes to water transport, especially among smaller boats, this boiler type is often the go-to choice for engine power.
• In certain regions around the world, simple vertical boilers still serve a purpose in steam donkeys—a reminder of their historical versatility.
• Beyond that, you’ll find simple vertical boilers operating in steam cranes and steam shovels, helping to drive those machines as well.

Advantages of simple vertical boiler

• low initial cost because of lesser parts
• Low maintenance cost
• Simple working
• Easy to install and replace
• Occupy small space on ground
• Simple vertical boiler has water level tolerance

Disadvantages of simple vertical boiler

• Vertical design limits its working in many places
• Because of the limited grate area steam production is limited
• Impurities settle down at the bottom thus prevent water from heating
• Boiler tubes must be kept short to minimize height. As a result, much of the available heat is lost through the chimney, as it has too little time to heat the tubes.

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