Boiler Steam Generator

Steam Boiler

Today, steam power installations consist of at least a steam generator, commonly known as a steam boiler, which serves as a means to convert water into pressurized steam. In English, a steam boiler is called a boiler, derived from the word "boil," which means to boil or vaporize. Therefore, a boiler can be defined as a device for generating steam that can convert the chemical energy from solid (solid, liquid, and gas) fuels into heat energy. The steam produced by a steam boiler is a gas resulting from the phase change of liquid to vapor or gas through vaporization, which requires a certain amount of energy. Heating a liquid substance causes the movement of molecules to become faster, allowing them to break free from their environment and turn into vapor. The heated water near the heating surface will have a higher temperature (lower density) compared to the cooler water, causing the hotter water to rise to the surface and the cooler water to sink. This continuous circulation process eventually results in the formation of steam. Steam produced by a steam boiler can be used for various purposes, including powering electricity generation and industrial utilities.

Understanding Steam Boiler

A boiler is a closed vessel where combustion heat is directed to water until hot water or steam is produced, which is a form of working energy. Water is a useful and inexpensive medium for transferring heat to a process. Hot water or steam at a specific pressure and temperature carries an energy value that is used to transfer heat in the form of thermal energy to a process. If water is boiled until it becomes steam, its volume will increase by about 1600 times, producing energy resembling easily ignitable gunpowder. Therefore, a boiler system must be well managed and maintained as it is equipment that needs careful attention.

Steam Boiler Working Process

The heat energy generated in the boiler system has pressure, temperature, and flow rate values that determine the utilization of the steam produced. Based on these three factors, the boiler system distinguishes between low-pressure/low-temperature (LP) and high-pressure/high-temperature (HP) conditions. In the case of low-pressure systems, steam exiting the boiler is used for heating liquids and operating machines (commercial and industrial boilers). In the case of high-pressure systems, steam is used to generate electrical energy by converting thermal energy into mechanical energy and then rotating a generator to produce electricity (power boilers). However, some systems combine both, utilizing high-pressure/high-temperature conditions to generate electricity, while the remaining low-pressure steam from the turbine can be used in industrial processes with the help of a heat recovery boiler.

The boiler system consists of a feedwater system, a steam system, and a fuel system. The feedwater system provides water to the boiler automatically as needed for steam generation. Various valves are provided for maintenance and repair of the feedwater system, and handling of feedwater is necessary as a maintenance measure to prevent damage to the steam system. The steam system collects and controls the production of steam in the boiler. Steam is transported through a piping system to the point of use. Throughout the system, steam pressure is controlled using a pressure regulator valve and monitored with pressure monitoring devices. The fuel system includes all equipment used to provide fuel to generate the necessary heat. The equipment required in the fuel system depends on the type of fuel used in the system.

Here are the components of the boiler:

Furnace

This component is the combustion chamber for the fuel. Some parts of the furnace include refractory, combustion chamber, burner, exhaust for flue gas, charge and discharge doors.

Steam Drum

This component is the storage for hot water and steam generation. The steam is saturated (saturated steam).

Superheater

This component is the place where steam is dried and ready to be sent through the main steam pipe, ready to drive a steam turbine or run an industrial process.

Air Heater

This component is a heating chamber used to heat outside air that is drawn in to minimize the humidity of the air that enters the combustion chamber.

Economizer

This component is a heating chamber used to heat water from condensed water from the previous system as well as new feedwater.

Safety valve

This component is a steam discharge valve if the steam pressure exceeds the boiler's capacity to handle the steam pressure.

Blowdown valve

This component is a discharge valve used to remove deposits in the steam pipe.

BOILER CLASSIFICATION

After understanding the brief process, the boiler system, and the components that make up the boiler system, it is necessary to know the diversity of boilers. Various boiler types have developed following technological advancements and evaluations of previous boiler products influenced by boiler exhaust gases affecting the environment and the desired steam product. Here are classifications of boilers that have been developed:

Fire Tube Boiler

Fire tube boiler types have characteristics that produce low steam capacity and pressure.

Water Tube Boiler

Water tube boiler types have characteristics that produce high steam capacity and pressure.

Solid Fuel boiler

Solid fuel boiler types have characteristics that the raw material for combustion is relatively cheaper compared to boilers that use liquid and electrical fuels. The efficiency of this type is better when compared to electric boilers.

Oil Fuel boiler

Oil fuel boiler types have characteristics where the raw material for combustion is the most expensive compared to all types. The efficiency of this type is better when compared to solid fuel and electric boilers.

Gaseous Fuel boiler

Gaseous fuel boiler types have characteristics where the raw material for combustion is the cheapest compared to all types of boilers. The efficiency of this type is better when compared to all boiler types based on fuel.

Electric boiler

Electric boiler types have characteristics where the cost of heating fuel is relatively cheaper compared to boilers that use liquid fuel. The efficiency of this type is the lowest when compared to all boiler types based on fuel.

Based on boiler use

Power Boiler

Power boiler types are primarily used to generate steam for electricity generation, and the remaining steam is used for industrial processes.

Industrial Boiler

Industrial boiler types are primarily used to produce steam or hot water for industrial processes and serve as additional heaters.

Commercial Boiler

Commercial boiler types are primarily used to produce steam or hot water as heaters and as additional units for commercial operation processes.

Residential Boiler

Residential boiler types are primarily used for low-pressure steam or low-pressure hot water that is used for housing purposes.

Heat Recovery Boiler

Heat recovery boiler types are primarily used to generate steam from unused hot steam. This steam is used for industrial processes.

Based on boiler construction

Package Boiler

Package boiler types have characteristics where the assembly of the boiler is done at the manufacturing factory and is delivered directly in the form of a complete boiler.

Site Erected Boiler

Site-erected boiler types have characteristics where the assembly of the boiler is done on-site where the boiler will be installed, and delivery is done per component.

Based on boiler operating pressure

Low Pressure Boilers

Low-pressure boiler types have characteristics where the operating steam pressure is less than 15 psig or produces hot water with pressure below 160 psig or temperature below 250°F.

High Pressure Boilers

High-pressure boiler types have characteristics where the operating steam pressure is above 15 psig or produces hot water with pressure above 160 psig or temperature above 250°F.

Based on fuel combustion method

Stoker Combustion

Stoker combustion types have characteristics where solid fuel is used for combustion. Solid fuel is introduced into the combustion chamber through conveyors or manually. This type produces combustion residue, either bottom ash or fly ash, which can pollute the environment.

Pulverized Coal

This process crushes coal with a ball mill or roller mill to reduce the coal size to less than 1 mm. The coal powder is then sprayed into the combustion chamber.

Fluidized Coal

This process crushes coal with a crusher, so the coal has a size of less than 2 mm. In this process, combustion takes place within a sand bed, and coal will ignite when it comes into contact with the sand.

Firing Combustion

Firing combustion types have characteristics where liquid, solid, and gas fuels are used for combustion, resulting in more even heating.

Based on boiler material composition

Steel

Boiler types made from steel primarily use steel for the steam area.

Cast Iron

Boiler types made from cast iron primarily use cast iron for the steam area.

Conclusion:

A boiler is a closed vessel where combustion heat is directed to water until hot water or steam is produced, which is a form of working energy. Water is a useful and inexpensive medium for transferring heat to a process. Hot water or steam at a specific pressure and temperature carries an energy value that is used to transfer heat in the form of thermal energy to a process. If water is boiled until it becomes steam, its volume will increase by about 1600 times, producing energy resembling easily ignitable gunpowder. Therefore, a boiler system must be well managed and maintained as it is equipment that needs careful attention.