Guide: The purpose and working principle of the boiler: The boiler is a device that uses the heat or other energy released from the combustion of fuel to heat the working fluid (intermediate heating medium) to certain parameters.
The purpose and working principle of the boiler:
The boiler is a device that uses the heat or other energy released from the combustion of fuel to heat the working fluid (intermediate heating medium) to certain parameters. The boiler used to heat water to turn it into steam is called a steam boiler, also called a steam generator. The boiler that is used to heat water to increase the temperature and convert it into hot water is called a hot water boiler; and the boiler that is used to heat an organic heat carrier is called an organic heat carrier boiler.
From the perspective of energy utilization, boilers are a kind of energy conversion equipment. In the boiler, the chemical storage of primary energy (fuel) can be converted into heat energy contained in the combustion products (flue gas and ash) through the combustion process, and then the heat is transferred to the intermediate heat carrier (such as water) through the heat transfer process. And steam), relying on it to transfer heat to the heating equipment.
This kind of intermediate heat transfer medium is a secondary energy source, because its purpose is to provide energy to energy-consuming equipment.
When the intermediate heating medium is used for heat-to-work conversion in a heat engine, it is called a "working fluid". If the intermediate heating medium only transmits and provides heat to the thermal equipment for heat utilization, it is usually called "heat medium".
Boilers can be divided into four categories according to their uses: power station boilers, industrial boilers, ship boilers and locomotive boilers. The first two types are also called fixed boilers because they are installed on a fixed foundation and cannot be moved. The latter two types are called mobile boilers. This article describes a stationary industrial boiler.
There are three main processes in the boiler:
(1) The fuel is burned in the furnace, and its chemical storage can be released in the form of heat energy, so that the flame and combustion products (flue gas and ash) have high temperatures.
(2), high-temperature flames and flue gas transfer heat to the working fluid (heat medium) through the “heating surface”.
(3). When the working fluid (heat medium) is heated, its temperature rises or vaporizes into saturated steam, or it is further heated to become superheated steam.
The above three processes are interrelated and carried out at the same time, realizing energy conversion and transmission.
Along with the conversion and transfer of energy, there is also the flow and change of matter:
(1) The working fluid, such as feed water (or return water) enters the boiler, and is finally supplied in the form of steam (or hot water).
(2) Fuel, such as coal, is burned in the furnace, and the combustible part is burned and converted into flue gas together with the original moisture content, and the original ash content remains as ash.
(3) Air is fed into the furnace, in which oxygen participates in the combustion reaction, and the excess air and the remaining inert gas are mixed in the flue gas and discharged.
The water first steam system, the coal first ash system and the air second smoke system are the three main boiler systems. The work of these three systems is carried out simultaneously.
Generally, the processes carried out on the fuel and flue gas side (including combustion, heat release, slagging, gas flow, etc.) are collectively referred to as "in-furnace processes"; the processes carried out on the water and steam side (water and steam) Flow, heat absorption, vaporization, steam-water separation, thermochemical processes, etc.) are collectively referred to as "in-boiler processes"