Boiler is a kind of energy converter. It is a device that heats working water or other fluids to certain parameters by using the thermal energy or other thermal energy released by the combustion of fuel.
The boiler is a kind of energy conversion equipment. The energy input to the boiler is chemical energy and electrical energy in the fuel, and the boiler outputs steam, high-temperature water or organic heat carrier with certain thermal energy.
The original meaning of the pot refers to the water container heated on the fire, the furnace refers to the place where the fuel is burned, and the boiler includes the pot and the furnace. The hot water or steam generated in the boiler can directly provide the required thermal energy for industrial production and people’s lives, it can also be converted into mechanical energy by steam power devices, or mechanical energy can be converted into electrical energy by generators. Boilers that provide hot water are called hot water boilers, which are mainly used in daily life. There are also a small number of applications in industrial production. The boiler that generates steam is called a steam boiler, often referred to as a boiler, and is mostly used in thermal power stations, ships, locomotives, and industrial and mining enterprises.
Classified by use Power station boilers: boilers used in thermal power plants with large capacity, high parameters, new technology and strict requirements. Industrial boilers: processes for producing textiles, printing and dyeing, pharmaceuticals, chemicals, oil refining, papermaking, etc. in various industries, Boilers that provide steam or hot water for heating and cooling. Domestic boilers: Boilers that provide low-parameter steam or hot water for various industries, enterprises, institutions, hotels, and service industries. Special boilers: such as dual-substance two-steam circulating boilers, nuclear fuel, ships, locomotives, waste liquid, waste heat, once-through boilers, etc.
Classified by pressure Atmospheric boilers (pressureless boilers, that is, boilers that operate at a normal atmospheric pressure) Low pressure boiler (pressure less than or equal to 2.5MPa) Medium pressure boiler (pressure less than or equal to 3.9MPa) High pressure boiler (pressure less than or equal to 10.0MPa) Ultra-high pressure boiler (pressure less than or equal to 14.0MPa) Subcritical boiler (pressure between 17-18MPa) Supercritical boiler (pressure between 22–25MPa)
Divided by type of working medium and output state The working fluid of a steam boiler is water, and the output fluid is steam. Steam is divided into saturated steam and superheated steam. The working medium of a hot water boiler is water, and the output medium is unsaturated hot water. Special working fluid boiler Boiler working fluid other than chemical fluids, such as historical mercury mercury steam boiler.
Divided by body structure type The combustion and endothermic evaporation of the boiler shell boiler are completed in a cylindrical body. It is divided into horizontal and vertical, such as early orchid development, artillery furnaces, and so on. Water-tube boilers whose main heating surface is tubes are a major improvement of the early boilers, with greatly improved safety and reliability. Boiler boilers, boilers that are not heated outside the fire side, are double boilers, single boilers and multiple boilers. The boilers are horizontal, vertical, etc.
By fuel or energy type When the boiler uses different fuels, it is called a boiler of that fuel or a mixed-fired boiler of two fuels. Fire-bed combustion boiler Fuel or boiler called grate or layer burner placed on the material bed to burn. It is generally lump-grained raw coal with the maximum capacity. Chamber-fired boiler fuel is burned in the furnace chamber or furnace. Generally, there are pulverized coal boilers, fuel oil, gas-fired boilers, etc., contemporary maximum capacity units, also known as suspension combustion boilers, and semi-suspension between stratum and room combustion. Combustion boilers, such as mechanical coal throwers, wind coal throwers, etc. Cyclone-fired boiler pulverized coal or fine-grained coal is burned in a cyclone. It has two types of horizontal and vertical. The combustion heat intensity in the cyclone is very high, and it is suitable for low-ash coal and difficult to catch coal. The boiling combustion boiler uses granular fuel to be placed on the fire bed, and the fuel layer is boiled into a fluidized state under the blowing of high pressure wind, also known as a fluidized bed boiler.
Divided by slag discharge method Slagging can be divided into solid and liquid. Solid state slagging is well known. Liquid slagging is known as liquid slagging, which forms a liquid when coal is burned at high temperature and flows into water to crack into translucent crystals as building materials.
According to the flue gas pressure in the furnace Negative and micro-positive pressure combustion boilers. The pressure of the flue gas from the furnace to the boiler outlet is lower than atmospheric pressure, so that a negative pressure system is established when the induced draft of the induced draft fan is greater than the blower. Conversely, when the supply pressure of the blower is greater than the suction capacity of the induced draft fan, micro-positive pressure combustion is formed. Micro-positive pressure combustion can reduce air leakage heat loss, but the sealing requirements for the boiler are much higher. The supercharged combustion boiler increases the pressure of the combustion flue gas to several atmospheres. The pressure flue gas is used as the working fluid of the gas turbine. It promotes the generator to generate electricity or drives the air compressor to obtain higher pressure air as a combustion medium. Combustion at higher pressure can accelerate the combustion speed. And improve heat transfer effect.
Divided by circulation The circulation of working fluid in water-cooled wall tubes of natural circulation boilers depends on the specific gravity difference of the working fluid between the rising and falling pipes to establish a circulation head to produce natural circulation. This boiler is only suitable for subcritical pressure. The auxiliary circulation boiler is controlled to add a circulation pump between the water-cooled wall and the downcomer to overcome the flow resistance and ensure the safe and reliable water circulation. It is suitable for boilers with subcritical and near-critical pressure. Once-through boilers pass from the water to the superheated steam outlet and rely on the feedwater pump pressure to pass through the boilers on each heating surface at one time. It is suitable for high pressures to super-supercritical pressures. In the combined circulation boiler, a boiler with a controlled forced recirculation system is added to the evaporation section of the once-through boiler to keep the water-cooled wall in good operating conditions during low load or startup, and enter pure DC operation at high load. The principle of a low-rate circulation boiler is similar to that of a control-circulation boiler, which promotes the reduction of the water-cooled wall circulation ratio to about left and right and accelerates the evaporation rate.
Divided by general arrangement The overall layout of the boiler includes “D”, “T”, “π”, “Tower” and “Box” types, which will not be described in detail.
According to the layout of the boiler room Boiler in the open air Partially open boilers Part of the boiler is located in the open air, and the other part is provided with simple houses. The interior layout boiler boilers are all in the boiler house.
Divided by ventilation method Naturally-ventilated boiler boilers rely on chimneys to draw in wind naturally, and are used by small boilers. Mechanical ventilation balance ventilation boiler Large-scale boiler flue gas system resistance is large, the air required for combustion is forced to be fed in by the blower, and the combustion flue gas is sucked out by the induced draft fan to maintain the resistance balance of the flue gas duct.
A furnace is an energy conversion device. The energy input to the boiler is in the form of chemical energy, electrical energy, and high-temperature flue gas thermal energy. After the boiler is converted, it outputs steam, high-temperature water, or an organic heat carrier with a certain amount of thermal energy. . Mostly used in thermal power stations, ships, locomotives and industrial and mining enterprises.