Fluidized bed combustion boiler [fèi téng lú]
Fluidized bed combustion boiler is a coal-fired boiler and one of the new combustion technologies developed in recent years. Modern fluidizing furnaces are thermal equipment utilizing "polymerized fluidized bed" technology. When fluid flows through a static granular material layer from bottom to top, if the flow rate exceeds a certain limit, the bulk material layer begins to expand, wriggle and become fluid, turning into a pseudo fluid state. This process is called fluidization of the bulk material layer. The up and down flipping of fluidized pellets is similar to the boiling of fluid, so it is also called a boiling layer. The thermal equipment that uses this method to process materials is called a boiling furnace.
Chinese name
Fluiding furnace
Foreign name
fluidized bed combustion boiler
Introduction Listen to the audio
The boiling furnace is mainly used to process ore with a particle size of 3~0 mm.
Boiling roasting is based on fluidization technology. Under the action of air flow, solid particles form a fluidized bed in a boiling-like state, which is called a fluidized bed or ebullating bed. In this way, the ore can be heated and reduced in a boiling state, which is beneficial to improving the quality of roasted ore.
The roasting furnace consists of a main furnace and an auxiliary furnace. There is a partition between the main and auxiliary furnaces, and the upper parts are connected. The furnace has a square section, the lower reduction zone of the main furnace is a circular cylinder, and a gas distribution plate is provided at the bottom. There are 10 layers of baffle plates in the auxiliary furnace. The furnace body is a brick structure with a metal casing. The main and auxiliary furnaces are equipped with three rows of gas burners at different heights for combustion. In addition, there are temperature and pressure measuring devices.
The working principle of the boiling boiler is to crush the coal powder to a certain particle size, blow it up with the wind, and burn it in a boiling state at a certain height in the furnace. Coal is burned in a boiling furnace, neither on the grate nor suspended in space like a pulverized coal furnace, but on the boiling charge bed. The outstanding advantage of the boiling furnace is that it has wide adaptability to coal types and can burn bituminous coal, anthracite, lignite and coal gangue. Another benefit is that it allows the fuel to be burned fully, thereby improving fuel utilization. The average temperature of the boiling material layer is generally between 850 and 1050°C. The material layer is very thick, equivalent to a large heat storage pool, in which fuel only accounts for about 5%. After the newly added coal particles enter the material layer, the temperature is dozens of times higher than that of the boiling material layer. The hot particles are mixed and can burn quickly, so coal gangue can be used instead. Production practice shows that the boiler operates normally when using coal gangue with an ash content of up to 70% and a calorific value of only 7.54MJ/Kg. The heat between 40 and 50 can be received directly from the bed.
Ebullating furnace
Working principle Listen to the voice
The solid fuel is lifted up by the upward flow of air in the furnace and tumbles up and down within a certain height range. A furnace that burns in a fluidized (or boiling) state is also called a fluidized bed combustion furnace. The boiling combustion method is also used in other kilns. The characteristics of the boiling combustion method are neither that the solid fuel is placed still on the grate for combustion like in the layer furnace, nor that liquid, gas or finely powdered solid fuel is suspended on the grate like the chamber furnace. Instead of burning in the furnace space, the solid fuel is broken into powder of a certain particle size, so that it burns in a state similar to boiling in the furnace. In China, the particle size of coal used in boiling furnaces is generally below 8 mm.
Related History Listen to Voice
Solid material fluidization technology was proposed by F. Winkler of Germany in 1921 and was first used in the chemical and metallurgical industries. Beginning in the 1950s, it was transplanted to the combustion field of boilers and gained development. The furnace is generally under normal pressure and is called a normal pressure boiling furnace. The boiling furnaces developed in various countries vary. The boiling boilers in the UK mainly use high calorific value bituminous coal in order to reduce the size of the boiler. Fluidizing furnaces in the United States use bituminous coal with high sulfur content and high calorific value to reduce pollutants such as SOX and NOX in the exhaust smoke. Countries such as China, Czechoslovakia and Poland focus on boiling furnaces that use inferior fuel. The pressure in the combustion chamber of a pressurized boiling furnace is greater than atmospheric pressure.
Some countries are experimenting with the use of pressurized boiling furnaces in gas turbine combined cycles, a system that can improve the cycle efficiency of power generation.
Working process Listen to the voice
The typical structure of the combustion chamber of a commonly used boiling furnace includes three parts: air distribution system, boiling bed, feeding and slag discharge system.
①Air distribution system. The bottom of the combustion chamber is an air distribution plate, with holes directly opened on the plate or many hoods with ventilation holes installed. The function of the air distribution plate is to carry the material layer and distribute the air rising speed evenly along the cross section of the furnace.
②Ebullating bed. A certain amount of bed material (including solid fuel and a large amount of ash or limestone particles) is placed on the air distribution board. During operation, when the air in the material layer reaches a certain rising speed, the bed material on the boiling bed will transition from a static state to a boiling state. This wind speed is called the critical boiling wind speed. In order to maintain intense boiling combustion conditions, the wind speed during normal operation of the boiling furnace is greater than the critical boiling wind speed, causing the material layer to expand to a certain height. The boiling height of the bed material is about twice that of the static material layer. The fuel in this volume is in a boiling state, so it is called a boiling bed. The small particles are taken out of the furnace by the air flow. Pipes arranged in the material layer are called buried pipes and can be placed vertically, horizontally or inclined. Water, steam or air can be passed through the tube to absorb the heat released by the combustion of fuel in the bed to maintain the bed temperature at 800~1000°C.
③Feeding and slag discharge system. Coal with a certain particle size range is fed into the material layer from the coal bunker through the coal feeder, and the burned coal slag is generally discharged from the overflow port.
Features Listen to Voice
The advantages of the boiling furnace are: ① It can not only burn high-quality coal, but also various types of low-quality coal that ordinary grate furnaces and chamber furnaces cannot burn; ② In the bed The heat transfer effect of buried tubes is very good, about 5 to 10 times that of ordinary boiler tubes; ③ Due to the low combustion temperature of the ebullated bed, the amount of NOX produced in the flue gas is small. If an appropriate amount of limestone or dolomite is added to the feed, that is It can remove sulfur from coal and reduce the SO2 content in exhaust smoke.
The disadvantages of the ebullating furnace are: ① The fine particle fuel in the ebullated bed is easily taken out by the flue gas, so the unburned loss is large, and the combustion efficiency is lower than that of the chamber furnace; ② There is more fly ash in the flue gas. The heating surface of the boiler is prone to wear and tear; ③ The air blower required for blasting has high air pressure, so it consumes a lot of electricity; ④ It is difficult to uniformly feed coal and arrange buried pipes in the ebullated bed. ⑤ When burning low-quality coal with high ash content, in order to prevent a large amount of fly ash from polluting the environment, a high-efficiency and large-capacity ash removal device must be equipped. Due to the above reasons, it is still difficult to develop large-capacity boiling furnace boilers.
Industrial application
It is mainly used in the production of sulfuric acid by contact method, and is used as a generating device for FeS2 to produce SO2.
Guess you like it
The boiling furnace manufacturer Dashi Intelligent Thousands of Comments on the Working Principle of the Boiling Furnace Recruiting Stoker Workers
Related Businesses
- Advertisement
Official website of Jiangsu Yongji Chemical Equipment Co., Ltd.
Jiangsu Yongji Group has been engaged in sulfuric acid equipment, pyrite, zinc concentrate, sulfur sulfur production and other equipment for many years. Welcome...
0514-87389989
The above merchants have joined the Baidu Reputation V Guarantee Plan
The content is all contributed by netizens, and Baidu Encyclopedia does not have any paid editing services
p>
Baidu Encyclopedia Bar Opinion Feedback Authoritative Cooperation Encyclopedia Agreement