While vertical boilers stand upright and erect, horizontal boilers are elongated. Within the choices of horizontal boilers, two of the most popular are horizontal fire tube boilers and horizontal water tube boilers. A general basis for identifying the two types are:
- Horizontal fire tube boilers are those where the combustion products are sent through the tubes as well as the water surrounding them.
- Horizontal water tube boilers are those where the combustion products surround the tubes through which the water flows.
Horizontal Fire Tube Boilers
With fire tube boilers, the water surrounds the tubes that house the hot gases and flame as well as the furnace. Most fire tube boilers will range in size anywhere from 15 up to 2,200 HP as a package. These boilers have design pressures between 30 and 160 pounds for hot water and 15 - 250 pounds for steam.
Fire tube boilers can be used in heating applications as well as process heating. These types of boilers are commonly found in schools, universities, and large medical facilities, such as hospitals. Fire tube boilers are also used in chemical plants and food processing plants. There are four different types of fire tube boilers:
Horizontal Boilers vs Vertical Boilers
Fire tube boilers can come with either a vertical or horizontal orientation. The horizontal design is offered in either a wetback or dryback design. The wetback design doesn't have the heavy refractory filled door associated with the dryback design. The problem with this door is that it's cumbersome to reseal and open.
However, it's important to understand without this large door, access to the rear tube sheet for boiler maintenance, inspection, and repair is significantly hindered. In contrast, a vertical firetube can have a burner mounted on the side of the boiler at the bottom or fire from the top down. The top-fire unit implements a mantle-type of burner that fires into the furnace.
In most instances, hot gases will only make a single pass through the convection tubes. This design uses extended surfaces to increase the coefficient of heat transfer, which affords an exceptional level of heat exchange before leaving out through the flue gas outlet located at the base of the firetube. Vertical fire tube boilers are used in a long list of industrial and commercial applications, especially when space is at a premium.
Water Tube Boilers
With a water tube boiler, the water circulates through the tubes and through the hot gases. Most of the water tube boilers available on the market today are designed to circulate the steam and water combination naturally.
It passes through properly-sized tube connected to the headers or drums, which provide the right amount of pressure necessary to circulate. It's imperative to understand that there are other designs of water tube boilers that require forced circulation. In these designs, the boiler incorporates a pump.
Horizontal Water Tube Boilers
The initial cost of most horizontal water tube boilers is low with a simple installation. With horizontal water tube boilers, you can typically change the setting to meet different fuel requirements, such as gas, wood, oil, or coal.
Replacing the tube is also a relatively easy task because all tubes within the horizontal water tube boiler are the same length, size, and diameter. The gas flows into the boiler from the firebox to the back of the boiler. Afterwards, it returns back through the tubes to the front of the boiler where it is discharged out of the stack.
Flex Tube Boilers
Smaller horizontal water tube boilers can be used in both industrial processes and commercial heating. One of the most popular commercial water tube boilers is the flex tube boiler. Flex tube boilers use serpentine tubes that are effectively connected to lower and upper headers.
This unique design allows the proper number of gas passes needed to absorb the interior heat contents. The flex tube boiler was originally created for comfort heating and hot water because it was much more resistant to the reality of thermal shock.
Contact Applied Technologies of New York
If you're in the market for a boiler and are considering horizontal boiler vs vertical boiler, it's imperative to consider capacity, operating pressure, lifecycle cost, and application. The experts at Applied Technologies of New York specialize in helping business owners choose the best boiler for their unique needs. We work across a variety of industries, including:
Contact Applied Technologies of New York today to schedule a consultation.