A boiler is a closed vessel where the heat of combustion is channeled into the water until it forms hot water or steam in the form of work energy. Water is a useful and inexpensive medium for transferring heat to a process. Hot water or steam at a certain pressure and temperature has an energy value which is then used to transfer heat in the form of heat energy to a process. If water is boiled down to steam, its volume increases by about 1600 times, producing a power that resembles explosive gunpowder, so the boiler system is equipment that must be very well managed and maintained.
Boiler Working Principle
The heat energy generated in the boiler system has a pressure, temperature, and flow rate that determines the utilization of steam to be used. Based on these three things the boiler system recognizes the state of low pressure-temperature (low pressure / LP), and high pressure-temperature (high pressure / HP), with that difference the utilization of steam that comes out of the boiler system is used in a process to heat the liquid and run a machine (commercial and industrial boilers), or generate electrical energy by converting heat energy into mechanical energy and then rotating the generator to produce electrical energy (power boilers). However, there are also those that combine the two boiler systems, which utilize high-temperature pressure to generate electrical energy, then the remaining steam from the turbine at low-temperature pressure can be utilized into the industrial process with the help of a heat recovery boiler.
The boiler system consists of a feed water system, a steam system, and a fuel system. The feed water system provides water for the boiler automatically according to steam requirements. Various faucets are provided for maintenance and repair purposes of the feed water system, handling feed water is needed as a form of maintenance to prevent damage to the steam system. The steam system collects and controls steam production in the boiler. Steam is fed through a piping system to the point of use. Throughout the entire system, steam pressure is regulated using a tap and monitored by a pressure monitor. The fuel system is all the equipment used to provide the fuel to generate the required heat. The equipment required in the fuel system depends on the type of fuel used in the system.
3. Main components of the boiler
The main components of the boiler consist of a Wall Tube, Main Drum, Primary Superheater, Secondary Superheater, Reheater, and Economizer. While the supporting components consist of Forced Draft Fan, MFO Heater, Air Preheat Coil, Air Heater, Burner, Gas Recirculating Fan, Soot Blower and Safety Valve.
1) Wall Tube
Boiler walls consist of tubes / pipes that are joined by a membrane, therefore it is called a wall tube. Inside the wall tube flows water that will be boiled. The boiler pipe wall is a pipe that has an inner thread (ribbbed tube), with the aim that the water flow in the wall tube rotates (turbulent), so that heat absorption becomes more evenly distributed, and to prevent overheating due to the initial evaporation of water on the pipe wall receive radiant heat directly from the combustion chamber.
The wall tube has two headers at the bottom which function to channel water from the downcomers.
Downcomer is a pipe that connects the steam drum to the bottom of the low header.
To prevent the spread of heat from inside the furnace to the outside through the wall tube, an insulating wall made of mineral fiber is installed on the outside of the wall tube.
2) Steam Drum
Steam Drum is part of a boiler that functions to:
a. Storing water to be heated in the evaporating pipes (wall tube), and collecting water vapor from the evaporator pipes before being flowed into the superheater.
b. Separating steam and water that has been separated in the furnace.
c. Regulating the quality of boiler water, by removing dissolved impurities in the boiler through continuous blowdown.
d. Adjust the water level so that there is no shortage when the boiler operates which can cause overheating of the boiler pipe.
The parts of the steam drum consist of: feed pipe, chemical feed pipe, sampling pipe, baffle pipe, sparator, scrubber, dryer, and dry box.
The water level of the drum must be kept at half the height of the drum. So that the amount of fill water that enters the steam drum must be proportional to the amount of steam leaving the drum, so that the water level remains constant. The maximum and minimum water level limits in the steam drum are half the drum height.
Setting the water level is done by adjusting the Flow Control Valve. If the water level in the drum is too low, it will cause overheating of the boiler pipe, whereas if the water level in the drum is too high, it is possible that water droplets will be carried to
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