To know which of these boiler types is the most convenient for you, let us see what a boiler is. “A boiler is an enclosed vessel in which a fluid such as water is heated to produce steam or the vaporized form of a liquid. The steam or hot water is then circulated through a piping system to transfer heat for various applications such as heating, power generation, and other processes. Boilers and associated pieces of equipment are efficient heat exchange systems. However, they can be dangerous if not properly maintained and operated”.

There is a wide variety of boilers for a myriad of applications; from heating a room, to drive the turbines of a utility company. Although all of them produce steam and hot water, they have different designs, differ in their operation, and use various types of fuel. As a result, it is convenient to know more about the boiler types available, so that you can decide which one is the most suitable for your application.    

Industrial Boilers

Fire-tube Boiler

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.

The installation and relocation of modern fire-tube steam boilers are possible because they are available as portable packages. Also, they are easy to maintain. Nevertheless, due to the massive amounts of water at high pressure that the boiler holds, it requires safe operating procedures. The users of fire-tube boilers are industrial and commercial facilities whose processes demand lower steam pressures from this type of boilers. 

Water-tube boiler

Water-tube boilers are highly efficient machines that, by their design, produce superheated dry steam at very high pressures. It feeds large amounts of vapor (several million pounds-per-hour), at very high pressures, up to 5,000 PSIG, to industrial processes. A water-tube industrial boiler has a larger size than a fire-tube.

They are the kind of boilers capable of feeding the processes of heavy industry and utility companies. However, the acquisition and installation costs are high. In the case of heavy industries, they are custom made on the installation site, which can be complicated and time-consuming. Furthermore, they are challenging to maintain. Thus, they require highly skilled personnel for operation and maintenance. 

Commercial Boilers

Commercial boilers have different ways to generate heat; firetube, small water tube, and electric resistance. Their ideal users are universities, libraries, office buildings, schools, laundries, hospitals, and other similar facilities,

Among the different boiler types, commercial boilers are some of the most diverse. These units can use propane, natural gas, electricity, or light oil to provide hot water or steam for process requirements or comfort heating. Based on the type of boiler selected and its application, these systems boost fuel efficiency as high as 99%.

A central heating boiler’s size is proportional to the size of the facility. The ideal size for a boiler is one that can cope adequately with the heating needs the coldest season of the year. A typical commercial heating system has four main components: The boiler produces the heat. The pipes, pumps, and valves, distribute the heat. Radiators and convectors, irradiate the heat to the specific room. Finally, there is a control system that regulates everything.

Home Boilers

Condensing Boilers

Condensing boilers typically extract over 90% of the heat from the fuel they burn, making them both cost-effective and energy-efficient. 

Combination Boilers

A combination boiler is a type of condensing boiler. They are highly efficient and compact, making them ideal for smaller homes. They can act as both, a water heater and also a central heating unit. 

System Boilers

A system boiler directly heats a house’s central heating and also produces hot water for the storage cylinder. It is a heat-only boiler. 

Boiler Types by fuel consumption

Another way that boilers can be classified is by the type of fuel that they burn. The most common are:

Coal 

Most industrial coal-fired boilers run on crushed or pulverized coal, which burns more efficiently than large coal clumps.

Gas and Oil

Gas-fired boilers operate using natural gas, most often a mix of methane, ethane, butane, pentane, or propane. Oil-fired boilers burn gasoline, diesel, and other fossil fuels.

Biomass

Biomass boilers burn plant materials like wood chips, wood construction debris, and corn husks.

Boiler Types by Combustion System

All the boilers mentioned before typically fall into one of the following combustion method categories.

Thermic Fluid

Thermic fluid heaters use fossil fuel inside a closed system. The sealed system can lead to greater efficiency, although it is not ideal for specific applications.

Fluidized Bed

It is the most common method used for burning solid fuels in boilers today; fluidized bed technology involves a bubbling hot mixture of water and material particles (like sand) with fuel in suspension. This mix allows for rapid heat transfer and cleaner, more efficient operations.

If you need one of these boiler types, Teems Steam is here to provide solutions for all of your boiler rental, sales, installation, and operation needs.

Sources: Superior Boiler, Odesie

A steam generator boiler uses a single tube coil instead of many smaller diameter boiler tubes. The generator forces the flow of hot water through the tube to convert it to steam during a single pass through the coil. 

Operation

The water containing coils go around the steam generator. The furnace heats the water, circulating down through the coiled tube. While traveling down, it turns to steam as it heats, and exits the boiler in a concentrated stream at a point at the bottom of the tube.

Advantages

  • It is generally less potent than a full boiler but it is easier to operate.
  • These generators are also smaller, making them more versatile when there is limited space available.
  • They are often used as auxiliary boilers because they start up very quickly, and in applications with very low load factors.
  • These boilers have a compact design, single water tube, and relatively lower water content. Consequently, they can be up and running at full power in a much shorter amount of time than larger boilers. As a result, they are useful in emergency and quick demand situations.
  • They generally cost less than larger boilers. For this reason, they may be more cost-appropriate for applications that do not necessarily require such high levels of steam.
  • They perform well at part loads and respond quickly to changes in loads. As a result, they dramatically increase part load operating efficiency.
  • The fact that they do not have pressure vessels means that in most locations, they do not require a boiler operator. 
  • A steam generator boiler is useful where it can give operational efficiency because it costs around 50% more for the same horsepower output than larger boilers.

For more information about steam generator boilers, ask our steam team here.

Sources: Superior Boiler

An industrial Boiler is a closed pressure vessel that produces high or low-pressure steam or hot water for industrial use. Generally, there are two types of boilers used in industrial applications—Fire-tube and Water-tube boilers.

The use of a fire-tube or water-tube industrial boiler depends on the industrial process for which they are going to generate steam or hot water. 

Fire-tube Industrial Boiler

Fire-tube 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.

A fired-tube industrial boiler is employed in processes that require low pressures, up to 250 PSIG. Furthermore, due to their size limitations, up to 50,000,000 BTU/hr, do not produce large amounts of steam. 

Operation 

The fire-tube 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, feeding a steam engine’s cylinders. 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.

Maintenance

  • The maintenance and cleaning operations of a fire-tube steam boiler relatively simple. They have easy access to its firesides, allowing the change of the fire tubes without further repair of the boiler.
  • The control systems are less complicated than the ones on water tube boilers.
  • The accessories required by a fire-tube boiler are available at economical prices, due to the relatively low pressures that they have to stand.
  • They are not only easy to operate, but they are also fuel-efficient.

Water-tube Industrial Boiler

A water-tube industrial boiler has a larger size than a fire-tube. It feeds large amounts of steam (several million pounds-per-hour), at very high pressures up to 5,000 PSIG, to industrial processes.

Water-tube boilers are highly efficient machines that, by their design, produce superheated dry steam at very high pressures. They are the kind of boilers capable of feeding the processes of heavy industry and utility companies.

Operation

In general, the water tube boiler design includes several drums. Specifically, the lower water drum and the upper steam drum. They are connected by tubes that form the furnace and convection section. The tubes that make up the furnace walls receive the heat and transfer it to the water contained in them, producing steam. Afterward, the hot water rises and enters the upper steam drum. There, the saturated (wet) steam exits off the top of the drum to feed processes or to produce superheated steam.

Maintenance

  • The larger the amount of steam and pressure produced, the larger the size of the boiler. As a result, they have to be assembled and installed on the site of their operation.
  • The preassembled “packaged” boilers, up to 1,500 PSIG, are easier to maintain than the larger ones.
  • The assembly and installation process of the boilers at the site where they are going to work can be comparatively difficult and time-consuming.
  • The difficulty of the cleaning process makes the maintenance process a complicated task that requires highly skilled personnel.
  • It is not possible to replace the tubes, because there is not a common standard of fabrication.

Conclusion

Fire-tube boilers are widely available in packaged form, allowing smooth relocation and installation. They are also easy to operate, control, and maintain. Nevertheless, due to their design, they are limited in their capacity to produce both–Large amounts of steam and very high pressures.

Water-tube boilers are highly efficient, produce large amounts of steam at very high pressures. The packaged type boilers are easier to maintain than the larger ones. Most water-tube boilers with a pressure capacity beyond 1,500 PSIG have to be custom assembled and installed in their working location. Due to their design and large sizes, they are challenging to maintain.

For information about the operation and maintenance of industrial boilers, contact our steam team here.

Sources: Superior Boilers

Fire-Tube Steam Boilers

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. 

Advantages of Fire-Tube Steam Boilers

  • Fire-tube steam boilers are widely available as “packaged” systems. Thus, their transportation and relocation are rather easy. 
  • Their installation is rather simple, if previously an adequate foundation and the connections to water, electricity, fuel, and steam systems are in their place by the time of arrival.
  • The maintenance and cleaning operations of a fire-tube steam boiler relatively simple. They have easy access to its firesides, allowing the change of the fire tubes without further repair of the boiler. 
  • The control systems are less complicated than the ones on water tube boilers.
  • The accessories required by a fire-tube boiler are available at economical prices, due to the relatively low pressures that they have to stand.
  • They are not only easy to operate, but they are also fuel-efficient. Their range of operation is between 600,000 BTU/hr to 50,000,000 BTU/hr.
  • They are used for space heating and diversity of industrial operations.

Disadvantages

  • Although fire-tube boilers are smaller in design, they have a larger water volume than similar size water-tube boilers, causing them to take longer to bring up to operating temperature from a cold start. 
  • Generally, this type of steam boilers generates a maximum output of 27,000 kg/h. Most commercial and industrial users that demand a higher output install multiple fire-tube boilers in tandem.
  • Fire-tube boilers can’t work with applications that require high pressure, beyond 250psig.
  • The cause is the large diameter that the cylindrical bodies of fire-tube boilers have.

Water Tube Steam Boilers

Water-tube boilers have a furnace that burns gas or another type of fuel, whose combustion heats water-containing tubes. As a result, the tubes produce steam by transferring the heat received to the water circulating inside them. Next, the resulting vapor reenters the furnace through a superheater to generate extra pressure. In particular, this device heats the saturated steam above the boiling point at very high pressure, turning it into superheated dry steam, which leaves the boiler with pressure high enough to drive large turbines. They are used by industries and utilities that demand high-pressure steam for their processes.

Advantages of Water-Tube Steam Boilers

  • They contain minimal amounts of water; therefore, they have a high capacity to respond to fluctuations in load and heat supply.
  • Their design containing small diameter tubes and steam drum, allows for the toleration of very high steam pressures, up to 160 bar. 
  • Water-tube boilers are highly efficient because they economize fuel by the use of an induced draft that feeds the furnace fire. Also by the recirculation water for preheating purposes, and for their capacity to produce superheat.
  • They can produce high steam pressures, up to 5,000 psi.  

Disadvantages

  • The degree of pressure that they produce limits their availability as preassembled “packaged” boilers, up to 1,500 psi.
  • The assembly and installation process of the boilers at the site where they are going to work can be comparatively difficult and time-consuming.
  • Their cost, including the installation, happens to be higher than fire-tube boilers.
  • The difficulty of the cleaning process makes the maintenance process a complicated task that requires highly skilled personnel.
  • It is not possible to replace the tubes, because there is not a common standard of fabrication.

Conclusion 

Fire-tube boilers are widely available in packaged form, allowing smooth relocation and installation. They are also easy to operate, control, and maintain. However, they take longer to respond to fluctuations in the pressure demand. Their uses are for space heating and diversity of industrial operations that do not require high pressure.

Water-tube boilers are highly efficient, produce very high pressures, and for their low water content, respond fast to fluctuations in demand for steam. The degree of steam pressure limits its availability as ‘packages” because as the pressure generated increases, so does the size of the boiler.

There is a point beyond which they have to be custom assembled and installed in their working location. They have big sizes, are challenging to maintain, and the cost of acquisition and installation is higher than fire-tube boilers.

If you require information or assistance for buying, renting, installing, and operating Fire-tube or Water-tube steam boilers, contact us here.

Sources: Superior 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

A boiler is a closed metal container with a heating element. Its purpose is to produce steam or heat water by increasing the temperature inside the chamber so that it is higher than that of the environment. Boilers also increase the pressure so that it is greater than atmospheric.

The combination of a boiler and a superheater is known as a steam generator.

How do boilers work?

The basic principle of operation of the boilers consists of a chamber where combustion occurs with the help of combustion air. Then, through the use of a heat exchanger, the transfer of heat is performed and the water is heated.

Taking that into account, the term “boiler” is a remnant of the past when steam boilers boiled water to generate steam. Modern boilers generally heat water using natural gas, butane, or propane.

This hot water is distributed to each radiator through a network of pipes. This causes heat to be distributed more evenly throughout the room and provides a more homogeneous temperature throughout the building during the winter months.

What is the structure of a boiler?

The actual structure of a boiler will depend on the type; however, in a general way, we can describe the following parts:

  • Burner: used to burn the fuel.
  • Home: it houses the burner inside and its where the fuel is burned to generate the hot gases.
  • Heat exchange tubes: The heat from the gases is transferred to the water as they travel through these tubes. It also generates steam bubbles.
  • Liquid-vapor separator: it is necessary to separate the drops of liquid water from the hot gases before feeding them to the boiler.
  • Chimney: it is the escape route of the fumes and combustion gases.
  • Housing: contains the home and the heat exchange tube system.

Boiler classification

Several characteristics define the type of boiler:

A. Depending on the relative position between the fluid and the flue gases

1. With multiple smoke pipes – Pirotubular.

2. With multiple tubes of water pipes – Acuotubular.

B. Depending on the number of steps:

1. One step of gas travel.

2. Multi-step.

C. Depending on the energy needs of the process:

1. Hot water boilers.

2. Thermal fluid.

Advantages of gas boilers at home

Price: There are boilers with a variety of prices.

Speed, comfort, and space: for home use, the heating process can be quite fast. You can regulate the consumption and temperature using the built-in thermostat. Also, they do not usually take up much space.

Shelf life In general: this type of boiler lasts longer than other heaters.

Cleaning: Natural gas boilers, unlike some of the alternatives, do not pollute, unlike other means of heating that do emit waste.

 

Like all industrial equipment, steam boilers require periodic maintenance and inspections to ensure their correct, safe, and efficient operation.

However, boilers are machines that compromise the continuity of production in many industries. This means that shutting them down can come at a high price, not only because of the maintenance cost but also on lost production.

It is for this reason that we establish an annual maintenance plan in which we perform important inspection tasks to detect most breakdowns preemptively.

What is the maintenance plan for a steam boiler?

    • Internal inspection of the pressure body, plates, household, and tubular beam to control the formation of incrustations or corrosion of building materials.
    • Hydro-washing of sludge deposited at the bottom of the body if it exists. This is important for optimal operation.
    • Change inspection door gaskets, always install new gasket materials and check cover seats. This will avoid many accidents within the company.
    • Measurement of plate thicknesses, and cylindrical body by ultrasound, we also record these values. It may be necessary to recalculate the maximum working pressure if these thicknesses are reduced over time.

Important aspects for your steam boilers

    • Disassembly of security elements. In the case of electromagnetic level controls, check floats, bottles, verify play in mechanisms, check the integrity of the mercury ampoules and check that the insulation of the cables is not damaged.

For the electrodes, the task is cleaning parts that are in contact with water, alignment check, caulking, and seals.

    • Hydraulic test of the work pressure equipment. Performed in order to verify that there are no leaks before and after maintenance (inspection of door seals, flanges, threads, etc.). After that, the container must remain pressurized for at least 15 minutes.
    • Verification of opening of safety valves at a regulated pressure. If possible, remove them for stamping on a test bench.
    • Inspection of refractory status in a burner or dry bottoms. Fill cracks if there are any or replace damaged parts with the appropriate materials.
    • Verification of the internal state of the burner and its cleanliness. Check the condition of cables and connection cards.
    • Start-up of the equipment where the operation of the control and safety elements will be checked.
    • Gas analysis and combustion regulation. Through this process, the percentage of the following gases will be determined: O2, CO2, and CO.

Also, the temperature of the gases in the chimney, and the thermal efficiency of the boiler will be measured.

    • Preparation of a technical report with the results obtained in the measurement of combustion efficiency and the general condition of the equipment, maintaining a history.

The steps for maintaining a steam boiler are quite specific, so you should entrust it to skilled professionals. In conclusion, if you need this type of service or any other related to preventive maintenance in your facilities, let us help you.