Boilers are closed vessels in which water or some other fluid is heated. In the United States, when the purpose of the boiler is not to boil water, it is more commonly called a furnace, or domestically, a water heater. These utilities are used in industrial, commercial and domestic settings in order to offer heated air and hot water, as well as steam in steam-operated machinery.
The purpose of a boiler is to provide hot water or to generate steam. While it can boil fluid, is does not have to. The hot water or steam produced by a boiler can be used for many different applications in many different industries. These industries include food processing, laundry, brewing, building, sewer cleaning. To learn about their wide range of applications in these industries, read the points below.
- Boilers are most commonly used in the food processing industry, as all food items need to be heated to inhibit microbial growth. Moreover, steam is used for cooking, sterilization of vessels, pasteurization, sanitization of packaging material and general cleaning.
- Heated water makes it easy to clean dirty clothes efficiently and remove tough stains. Moreover, the steam produced by boilers are also used for ironing, just like a home steam press.
- Wineries and breweries use boilers at large scale. In the large boilers, a combination of raw materials is heated for a number of hours to start the fermentation process, which breaks the material into alcohol. The steam also is used for cleaning barrels and other equipment so that nothing mixes with your favorite drink.
- In the building industry, manufacturing of bricks involves the use of boilers. Steam hardens the brick under high pressure and in a special chamber.
- In the sewer cleaning industry, steam is used to clean jammed piping systems by exposing the pipes to high-pressure steam, which cleans the blockades.
Hot water boilers provide hot water for heating systems, which are commonly used for providing optimum room temperature, used as protection against freezing, for dishwashing at large scales, car washing, along with many other applications. Whereas, industrial boilers, that generate steam, have application in power generation, cement and brick production, as well as soil steaming in agriculture.
Boiler – Fulton
Boiler – Fulton
Boiler – Unilux Advanced Manufacturing, LLC
Boiler – Fulton
The earliest boilers were invented in the 1700s; they were kettle-esque and used on a small scale. The first industrial boilers, though, weren’t invented until 1867, patented by George Babcock and Steven Wilcox. In those early days, the steam boiler was used to power steam locomotives and steam engines. Its uses were industrial and quite dangerous, as early operators did not fully understand the relationship between temperature and pressure. Because steam boiler applications were so dangerous, concerned citizens and workers contemplated getting rid of steam boilers altogether, or at least until engineers made advances in their safety.
Today, boilers operate in many different settings such as schools and office buildings. The materials, design and construction have all improved to the point that fear is no longer a factor. Accidents do still occur but with less frequency and with fewer injuries or fatalities. Boilers are now an extremely valuable part of life and can be found in almost any environment.
Once quite large, boilers are becoming smaller and smaller in order to fit into tight spaces, though some boilers, like those used industrially, must remain their size in order to produce the necessary amounts of steam and water. Mobile boilers are now available and can be used in military, emergency or temporary situations to provide steam for heat or power. Even as technology continues to make significant advances, boilers will most likely remain a critical part of life for years to come.
How It Works
Depending on its details, like its heating source and whether its creating heated water or steam, an individual boiler will vary in its working process.
However, in general, boilers work like so: Inside a cylinder-shaped heating chamber, a burner generates heat; the heat moves through a heat exchanger to the water, and the heat warms the water.
When steam is the name of the game, it moves under its own pressure and transports to the desired place through a cache of tubes. For efficiency and to save water, once it’s done, the condensed steam will return to the furnace to be heated once again. Said furnace is furnished with water continuously to compensate for lost water.
Boilers can be categorized in a number of different ways. First is by their fuel source, which may be gas, oil or electricity (except in the case of central boilers, which are wood-fired).
Gas boilers are fueled by natural gas and use a natural gas flame to heat water to a specified temperature or to its boiling point, thereby producing steam. They are the most common type of boiler used for heating applications in the United States.
Oil boilers use oil either as fuel for the furnace or to replace the water generally found in boilers and produce hot gases that travel through the piping system.
Electric boilers offer efficient, clean and safe water heating. Unlike appliances that provide heating through the process of combustion, electric boilers eliminate the problems with carbon monoxide, back drafting, pilot lights, gas piping and venting.
A less common boiler heat source is biomasses, such as wood logs, wood chips or wood pellets.
Another way to categorize boilers is by their heat exchanger arrangement. Common boilers in this category include the water-tube boiler, fire-tube boiler, and sectional boiler.
Water Tube Boiler
In the water tube boiler design, water tubes are installed in the boiler drum. When the water filled tubes are exposed to heated flue gas, the water boils and evaporates to make steam. This type of boiler is more thermally efficient and saves a significant amount of energy.
However, the design has downfalls too. First, their construction is complex. Second, the water fed into the system needs to be treated, since water with contaminants can clog tubes; all solids in the water are required to be filtered out before water enters the boiler. This design is preferred when the demand of the steam is high and when high pressure is required, therefore, they are also called high pressure boilers.
Firetube boilers generate steam using tubes carrying hot gases from the furnace pass through a water-filled drum. This design is a common construction found in the boiler industry, perhaps because the fire boiler is so easy operate, in comparison with the water boiler. Unlike the water tube design, fire tube boilers are not complex, which makes them less expensive than the alternative. However, they are bulky because of the chunky outer shell.
The design is used when low pressure steam is required, thus they are also known as low-pressure boilers.
This design has evolved over time and three variations are available on the market. The first is the horizontal return tubular boiler, which has horizontal tubes and a separated furnace. The second design is known as scotch marine or shell boilers, in which both the firetubes and combustion chamber are designed in a single shell. The last variation is known as firebox boilers, which has a specialized water-jacketed firebox.
Sectional boilers have the most basic design, in which different sections are casted and bolted together. The combustion chamber surrounds the water chamber and heat is exchanged directly. The boilers are used for hot water needs, since it is made from cast iron.
Next, boilers can be categorized by the level of pressure they maintain.
High Pressure Boiler
Another way to increase efficiency is by using a high-pressure boiler, which maintains an operating pressure greater than 15 PSI; some models achieve pressures as high as 1,000 PSI.
Low Pressure Boiler
Low pressure boilers have pressure less than 15 PSI and are used mostly in smaller buildings for heating a space.
Other types of boilers not under these umbrellas include: industrial boilers, combi boilers, condensing boilers and steam boilers.
Industrial boilers are used either as part of a heating system or to individually generate hot water or steam for various industrial and manufacturing processes. They are much larger in size and built from heavy-duty materials to ensure safety, durability and performance.
Industrial boilers' working principle is the same as pressure cookers in your kitchen. The difference is in the scale and ability to withstand high pressure. They are specially designed to manage pressure as high as 30 bars, and are thus made from chunky steel plates that are welded together. However, just like pressure cookers, they are enclosed vessels made to withstand high pressures and to heat water by a fuel source. The steam generated by the boilers is used for humidification and for industrial heating.
Combi boilers are different from conventional hot water boiler models because they do not store hot water but rather heat it rapidly on demand. They have a second heating element to speed the heating process and maintain a steady supply for as long as the boiler runs.
Condense, or condensing, boilers are able to recover energy that would normally be expelled through the flue by condensing the escaping water vapor back into liquid water. Because the boiler uses latent heat to boost its efficiency to above 90%, it is considered a high efficiency boiler.
Industrial Steam Boiler
Steam boilers produce steam for heating large buildings such as factories and warehouses, and they can also be used to create steam for power. Hot water boilers such as the steam boiler are an important part in hydronics because they heat the water that circulates through pipes and into radiators, baseboards and other heat exchangers.
Thermic Fluid Heater
This type of industrial heating equipment is used only to heat water; it does not create steam. As its name suggests, it used thermic fluid.
The last option that you can come across is the hybrid design, which uses a different arrangement of heat exchangers and combustion chamber to achieve high efficiency. One example is the electric steam boiler.
An industrial boiler consists of a heating chamber, also known as a vessel or a furnace, which typically is in the shape of a cylinder, a burner, and a heat exchanger, which is typically made up pipes and tubes. The other parts include a chimney to emit combustion gases, a pump or a fan, and a pressure safety mechanism.
Design and Customization
Usually, boilers manufacturers rely on fire-tube or water-tube designs as their baseline design. However, as we demonstrated in the “Types” section, there are many different types of boilers, including custom boilers. To make configuration decisions, manufacturers consider factors including: system load type, ideal application fuel source, the size of the operation, application standard requirements and restrictions, the temperatures that need to be reached, and the nature of the fluid being heated.
Boiler manufacturers typically construct them from stainless steel, aluminum or cast iron. The pressure vessel itself is usually made of steel or alloy steel. This part of the boiler is not usually made from stainless steel because it’s susceptible to corrosion and stress corrosion cracking. However, heating areas not to be exposed to boiling water are often made from ferritic stainless steel. Also, electrically heated shell boilers can be made from stainless steel in the European Union, under the European "Pressure Equipment Directive," for sterilizer and disinfector steam production.
A boiler system is fairly easy to customize; it can be customized in size, load capacity, efficiency, material, fuel source, and heating element configuration.
A system load is measured at specific temperature and pressure in terms of Btus or pounds of steam. Typically, there are three types of loads, heating load, process load, and combination load. System load helps to select the size of a boiler that will serve the requirement.
To make your boiler system as efficient as possible, manufacturers will consider a number of factors. First, they will assess combustion efficiency and thermal efficiency.
Percentage of potential energy that is converted when chemical potential energy of fuel is changed to produce thermal energy.
Percentage of potential fuel energy converted to thermal energy for producing steam or heated water
Second, they will customize boiler controllability. Boiler controllability, also known as turn down ratio, defines efficiency of boilers and heating systems.
You can choose from a number of fuel sources, including propane, natural gas and light oil. For most applications, we recommend natural gas, as it leaves little residue, requiring you to spend less on maintenance. Sources such as heavy oil and solid fuel are being phased out under new guidelines.
Safety and Compliance Standards
With the advent of stricter environmental regulations, it is important that you consider the rules and codes implemented regarding boilers. The rules that you must research include the American Society of Mechanical Engineers rules, insurance guidelines, and state rules regarding boilers.
The factors and parameters discussed for industrial boilers need further research to understand how they all together and individually affect the performance of a boiler. Therefore, it is recommended to review the literature given in American Society of Mechanical Engineers (ASME), which explores the factors with better insight.
Things to Consider
Before purchasing a boiler, there are some parameters you should consider.
First, do you need just one boiler, or do you require a system with multiple boilers? Additional boilers offer the advantage of backup. Some systems, though, do realistically require a backup. Figure this out by assessing the risk level of system breakdown, weighing future maintenance costs against the upfront costs of a larger operation, and whether or not you are planning to expand your application in the future.
Second, what space do you have for boiler installation?
Third, talk over your fuel options with your supplier. In a standard operation, almost 10 percent of an operating budget goes to fuel. Thus, you must estimate boiler-fuel consumption rate, annual fuel use, annual fuel cost, and potential annual fuel savings.
After considering all of these factors, you need to determine potential incremental efficiency, as well as, what will be the payback period against the investment.
With the number of options available on the market, choosing an industrial boiler can be a daunting task. To help guide you through this world, you need a boiler supplier on whom you can rely. The right manufacturer for you must not only be competent, but also intuitive, experienced, and able to deliver on all of your specifications, including turnaround times and budget. Find a great manufacturer like this by perusing the websites of those high-quality companies we have listed near the top of this page. Good luck!
– A test that measures the relieving capacity of boiler safety relief
– The air that surrounds
– A burner
in which the fuel, in either a gaseous or finely divided form, is burned
in suspension. The air for combustion is supplied by bringing it into
contact with the fuel as it is drawn through one or more openings by the
lower static pressure created by the velocity of the fuel stream.
Boiler Accessories- include things like safety valve to release pressure, a water level indicator, a low-water cutoff switch, a top feed for water injection, and a chemical injection line.
– The removal
of a boiler from service for a length of time. A boiler may be laid-up
dry or wet.
Boiler Parts- boilers use a variety of different parts, both big and small, including valves, level indicators, switches, piping, heating components, pressure vessels, and more. In order to keep a boiler running efficiently, it is important to maintain or replace these components as they begin to function less effectively or stop working altogether.
– Pressure of
the steam of water in a boiler, generally expressed in pounds per square
inch (psi) and corresponding temperature.
– A valved port
used to vent air from a full boiler and to prevent a vacuum from forming
when the boiler is drained. Boiler vent openings are located on the highest
part of the waterside of the boiler.
– The draining
of a portion of the water in the boiler in order to remove the heavy sludge
that tends to settle at the bottom. This process is done periodically.
Amount of heat needed to raise or lower the temperature of one pound of
water by one degree Fahrenheit under standard pressure.
– A pipeline that
passes around a control in order to allow the boiler to be operated manually
without having to use the control.
– A small,
continuously draining stream of water that controls the quantities of
impurities in a boiler.
– A pressure
control setting at which the boiler automatically turns on.
– Connections between
parts of a boiler
to equalize pressures.
– A door in a
furnace or boiler setting that is designed to be opened by a pre-determined
– The lowest temperature
at which, under specified conditions, fuel oil gives off enough vapor
to flash into a momentary flame when ignited.
– An enclosed space
of a boiler in which the fuel undergoes combustion.
– A flame which is utilized
to ignite the fuel at the main burner or burners.
– A vertical conduit that,
due to the difference in density between internal and external gases,
creates a draft at its base.
– The vapor phase of water,
unmixed with other gases.
– The change from
liquid or solid phase to the vapor phase.
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