Steam Boiler Parts And Their Functions
The main components of the boiler consist of furnace, membrane walls, boiler shell, economizer, cyclone, water storage tank, deaerator, coal bunker, hopper, conveyor and chimney.
The following will be discussed one by one: 1.
Furnace or also often called the furnace is a device used for heating. The name comes from the Latin Fornax which means the same as the oven . Sometimes people also refer to kilns . The process of heat transfer in a furnace occurs in three ways:
- Radiation heat transfer, where there will be a radiant heat from the fire and will be absorbed by the fluid that flows water in it.
- Heat transfer by conduction, heat flows through the conductor from the side of the pipe which receives heat into the side of the pipe which gives heat to the water.
- Convection heat transfer, heat that occurs with the contact of water molecules so that heat will spread to each flow of water.
- Membrane Wall
The wall consists of tubes / pipes that are joined by a membrane, therefore called the membrane wall. Inside the membrane wall flows water to be boiled. Tube / pipe construction is from the bottom up where the bottom of the pipe is filled with heavier water mass and it is expected that at the top it has become steam through a combustion process where lighter mass steam will rise to the top naturally.
Membrabe wall has two headers on the bottom that serve to channel water from downcomers . Downcomers are pipes that connect the steam drum to the bottom of the low header. To prevent the spread of heat and to minimize contact with humans, the outer side of the membrane wall is mounted on an insulating wall made of rockwool wire blankets.
3 Shell Boilers
The boiler shell in the picture above is the type of fire tube. In a fire tube boiler , hot gas passes through the pipes and boiler feed water is in the shell to be turned into steam .
The function of the boiler is:
- Collect water to be heated in the vapor pipes ( membrane wall ) and collect steam from the membrane wall and tube bundle before it is flowed to the factory or production room.
- Separating steam and water that results from heating in the combustion chamber ( furnace ).
- Regulate water quality, by removing dissolved impurities in the boiler through continuous blowdown .
- Adjust the water level so that there is no shortage of water when the boiler is operating, because if there is a lack of water it can cause overheating of the pipe.
The water level of the drum must always be kept at a fixed height so that the amount of fill water entering the boiler is proportional to the amount of steam leaving the boiler so that the water level can be constant.
Economizer absorbs heat from combustion gases after passing through the boiler, to heat the filler water before entering the boiler. The heat given to water is in the form of sensible heat (heat that causes an increase in temperature but the phase / form does not change). This water heating is done so that the temperature difference between the fill water and the water in the boiler is not too far away, so there is no thermal stress (the voltage caused by heating) in the boiler. In addition, by utilizing combustion residual gas, it will increase the efficiency of the boiler and the process of forming steam faster. Economizer in the form of water pipes installed in the place through which the combustion gas.
The heat transfer that occurs in the economizer occurs in the opposite direction of the flow of the two fluids ( counter flow ). Boiler drum filler water flows upward toward the boiler, while heating air flows downward.
Cyclone is a dust collector that uses the principle of centrifugal force to separate dust particles from the air based on differences in masses of air and particulates.
Components in the cyclone consist of:
- Vertical cylinders that form ker ucut ( cone ) with the bottom of a funnel shape.
- Dirty air i nlet at the top .
- Inner cylinder and clean air outlet.
- Dust bin at the bottom to collect dust particles .
The working principle of the cyclone is as follows:
- Particles from the flue gas are separated by making a centrifugal force.
- Flue gas that contains a lot of dust particles into the cyclone inlet and rotated in the cyclone cone with the aim of separating dust particles and air using the principle of weight difference. Dust particles heavier than air will fall and fall into the dust bin .
Cyclone performance is very much influenced by :
- The particle size , because according to the stroke law states that the particle diameter el is directly proportional to the terminal setting velocity so that the greater the particle size, the cyclone efficiency will increase.
- The smaller the diameter of the cyclone cone , the higher the efficiency.
- S emakin large viscosity of the efficiency of the cyclone is getting smaller.
6 Water Storage Tank and Deaerator
Water storage tank is a device used to collect water from the water softener to the boiler. In addition to storing water, preheating also occurs here before it is heated again in the economizer . The heat source is taken through the steam injection line pipe and the temperature in the water storage tank can reach more than 100 0 C. The water storage tank is also equipped with a level gauge to see the level of water inside and also equipped with sensors.
Deaerator is a tank that serves to separate oxygen from water because O 2 levels that are too high in air softeners can cause corrosion in pipes in boilers and other supporting pipes. Deaerator works based on the nature of oxygen whose solubility in water will decrease with an increase in temperature.
7 Coal Bunker
Coal bunkers are the final storage places for coal which are stored in bunkers (silos) before being used as fuel. The coal bunker is given a height detection device or level indicator, so that when the coal bunker is full, automatically the coal entering the coal bunker through the conveyor will stop .
A hopper is a fuel storage device such as a silo but has a diameter that is generally larger than a silo . This storage device is usually made of carb on steel where the bottom is cone-shaped to minimize the point of dispensing coal, right below it, there is a conveyor to move from the hopper to the coal bunker .
A conveyor is a device used to move goods from one place to another . C onveyor usually used to move the goods that are continuous and sustainable, in this case move barubara from the hopper to the coal bunker .