steam boilers

Fire-tube steam boilers are a cylindrical vessel in which the flames in a furnace produce hot gases that pass through tubes surrounded by water. Consequently, the heat contained in the tubes transfers to the water, heating it and producing steam.

Fire-tube can be either low or high pressure. Most low-pressure boilers produce hot water for heating purposes, while the high-pressure boilers produce steam for process use.

This article contains technical descriptions. Hence, go directly to the CONCLUSION section at the end of the post if you are interested in a summary.

Design

They have two types of design, wet-back or dry-back. In the first, the boiler has a water-cooled turn around a chamber used to channel the gases from the furnace into the tube banks. Tube removal and cleaning can be more complicated than in the dry-back design.

The dry-back design has a larger and swingable refractory-lined rear door integrated with the vessel. Through this door, combustion gases transfer from the furnace into the tube banks. It requires more refractory maintenance than the wet-back design.

Operation.

The fire-tube steam boiler holds a firebox where flames produce hot combustion gases. A cooling jacket that contains water surrounds the firebox and connects to the long cylindrical boiler shell. The water surrounds a series of fire-tubes or flues that heat the water, generating saturated (wet) steam. That steam rises to the boiler’s highest point, called steam dome, where it accumulates.

A regulator located in the steam dome controls the exit of the steam. A series of larger flues (tubes) situated at the top of the boiler, conduct the saturated (wet) steam back turning it into dry or superheated steam. The boiler produces superheated steam and exhaust gases. The superheated steam, most of the time, feeds a steam engine’s cylinders and rarely feeds a turbine. Those machines turn the energy of the steam into mechanical work. The exhaust gases are recycled to preheat the water that enters the boiler, thus increasing its efficiency.

The fire tubes run through the length of the boiler and make a turn. That run before making the turn is called a pass. Therefore, a three-pass boiler has three sets of tubes, while a four-pass boiler has four. A boiler with more passes has a higher heat extraction rate and is more efficient than one with fewer passes. The fire–tube steam boilers hold pressures to a maximum of 250 psi and 750 horsepower.

Thermal Efficiency

The addition of tubes to the drum containing the water increases the heating surface of the boiler. The higher the heating surface, the more significant the amount of heat that transfers from the hot gases to the water, thus, increasing the thermal efficiency of the boiler. The thermal efficiency is the ratio of the heat transferred from the fuel to the heat absorbed by the water. Steam boilers that have an improved design and high heat transfer rates reach a thermal efficiency of 80% – 85%.

Safety

Every boiler technician must know the basic principles of boiler operation and maintenance because the safe operation of a boiler can prevent accidents. Steam boilers hold large quantities of very hot water under high pressures. When the pressure in the boiler is close to 100 psi, the temperature of the water reaches more than 300 degrees F. If the pressure suddenly drops to zero, without a corresponding drop in temperature, the water instantly turns to steam, increasing its volume enormously. The result of this reaction may be an explosion. Modern fire-tube boilers have built-in safety controls that prevent this type of event from happening. For more information, contact us here.

Conclusion

Fire-tube steam boilers are cylindrical vessels that hold water that surrounds a set of tubes conducting hot gases produced by a furnace. Consequently, the heat in the tubes transfers to the water surrounding them, producing steam.

Modern fire-tube steam boilers are sold as packages that can be installed rather fast and can be relocated elsewhere. They are easy to maintain. Nevertheless, due to the massive amounts of water at high pressure that the boiler holds, they require safe operating procedures.

Industrial and commercial applications whose processes require lower steam pressures demand this type of boilers. If you require information or assistance for buying, renting, installing, and operating Fire-tube steam boilers, contact us here.

Sources: Superior Boilers

From all the industrial boilers in the market, you want to buy one that meets your needs and runs at pick operational efficiencies for the longest period of time. Accordingly, there are many factors affecting the buying decision that you have to consider. Those key aspects are types of boilers available, price, lifetime efficiency, operational specifications, size, safety, maintenance, fuel, and accessories.

Types of Industrial Boilers

There are three types of industrial boilers, water tube, fire tube, and firebox. They are configurable for use in many types of operations.

Water Tube Boilers

They are the type of industrial boilers where water passes through tubes while the hot combustion gas flows on the other side of the pipes. Water Tube boilers are more expensive and efficient and less dangerous than fire tube boilers. They produce high temperatures and steam pressure.

Fire Tube Boilers

They are the type of industrial boilers where heat and gases of combustion (from the furnace) pass through tubes that are enclosed on water. They have a lower cost than water tube type and require less maintenance. However, they are not capable of producing high heat, pressure, and steam.

Fire Box Boilers

They are a traditional “locomotive” type of boiler. The “firebox” is the space where the heat originates, producing hot gases that pass through the tubes, heating the fluid. It is reliable but limited in its applications.

Price of an Industrial Boiler

A steam boiler is an expensive piece of equipment. Consequently, price is a crucial variable to be considered when buying one. Nevertheless, in the long run, you may spend more money in downtime for repairs, maintenance, and fuel consumption if you buy a lower price boiler.

Lifetime Efficiency

It is crucial to make the buying decision with the lifetime efficiency of the boiler in mind. Hence, It would be best if you did a cost-benefit analysis for the expected useful life of the boiler. Specifically, you should consider: running times, operational costs, maintenance schedule, and costs, and expected lifetime of the machine. Buying the right kind of boiler saves you money and trouble in the long run.

Operational Specifications

The operational specs give you the matching points with the demands of your facility. Therefore, it is essential to know them beforehand. For instance, if your plant demands high temperature and pressure for its production processes, you need a high-performance boiler. Furthermore, they are a vital input in the feasibility study. Some of them are heat output capacity, temperature, thermal efficiency, and maximum pressure.

Size of an Industrial Boiler

It is vital for various reasons. The more steam you need for operating the facility, the larger the boiler size that you require. Consider that the run costs of an oversized boiler are higher compared to the run costs of an undersized one. Nevertheless, the latter may not be able to meet the high-temperature requirements needed by your facility.

Industrial Boilers Require Safety First

Safety is a primary consideration when buying a boiler. Handling the operation of a boiler is a highly technical job that requires well-trained personnel. They must follow the operational procedures in detail, due to the potential hazard of the high temperatures and pressures involved. High-quality boilers take safety first as an original manufacturing specification. Accordingly, you should check the safety track record of the specific brand and model that you want to buy.

Maintenance of Industrial Boilers

It is vital to take into consideration the maintenance schedule of the boiler. Since you want it to be functioning at peak efficiency for the longest time possible. Additionally, low-quality boilers require frequent repairs, which means that they have to be replaced sooner than one of higher quality.

Fuel for Industrial Boilers

Before buying a boiler, the owner has to consider the type of fuel that the boiler uses, evaluating its availability and cost. Boilers use oil, electricity, coal, natural gas, and propane.

Accessories

Many accessories are necessary to complement the operation of the boiler: de-aerators that remove excess oxygen from the water, safety valves, and others.

Conclusion

You are responsible for the operation of a facility that depends on the high efficiency, long-running times, and extended use-life of an industrial boiler. Therefore, it is crucial to make a decision that you are not going to regret later on. Because you don’t want to have your plant shut down for boiler repairs. Or worse, to have part of your personnel suffering injuries for malfunction of the boiler that you selected.

Accordingly, you want to buy the right model and size of the boiler for your plant requirements. Afterward, you should install it correctly and keep it well operated and maintained by highly skilled personnel. Then, you will have your facility operating at optimal levels for a long time. We have that boiler, call us here to have a conversation about it.

Sources: Superior Boilers