What do the internal circulation and external circulation of fluidized bed boiler mean?

Circulating fluidized bed boiler adopts fluidized combustion mode, which is especially suitable for inferior coal fuel and biomass bulk materials. The process of circulating fluidized bed boiler includes internal circulation and external circulation, which is the basic technical point of the boiler. What do the internal circulation and external circulation of circulating fluidized bed boiler mean?

Internal circulation and external circulation of fluidized bed boiler

The internal circulation of circulating fluidized bed boiler refers to the circulation of materials in the hearth. At a certain airflow speed, the particles no longer move upwards but move downwards along the wall, and the particles keep rising, agglomerating and sinking, so as to exchange heat and mass in the fluidized bed.

The external circulation of circulating fluidized bed boiler refers to the circulation process in which the particles carried by flue gas are separated by the gas-solid separator outside the boiler and then returned to the furnace through the material return device.

Circulating bed boiler has obvious advantages

Circulating fluidized bed combustion (CFBC) technology, as a new and mature clean coal technology with high efficiency and low pollution, has many advantages that other combustion methods do not have, so it is widely used. As a professional circulating fluidized bed boiler manufacturer, ZOZEN Boiler is a large industrial boiler manufacturer with A-class boiler manufacturing qualification, advanced tooling and equipment, and strong R&D strength. By optimizing the structure of the boiler and reasonably controlling the internal circulation and external circulation of the circulating fluidized bed boiler, the boiler is efficient, energy-saving and environment-friendly, and the continuous operation time is not less than 7,000 hours.

1) Wide fuel adaptability. Use combustible inferior fuel, coal gangue, coal slime, oil shale, petroleum coke, slag, bark, waste wood, sludge, etc.

2) Combustion is stable and efficient. Thanks to the existence of a large number of high-temperature materials, the fuel is quickly heated to above the ignition temperature after entering the furnace. As the fuel quantity is very small compared with the high-temperature materials quantity, there are no problems of fire extinguishing and unstable combustion in circulating fluidized bed boilers. However, most of the unburned fuel can be recycled many times through the cyclone separator, with long residence time and high combustion efficiency;

3) Excellent environmental protection performance. Circulating fluidized bed boiler can significantly reduce the sulfur dioxide emission concentration of flue gas by adding limestone for desulfurization, and the original emission of nitrogen oxides is lower than that of pulverized coal boiler.

4) The fuel preparation system is simple. The coal particle size is 0~13mm or 0~8mm, and there is no coal grinding system, which is greatly simplified compared with pulverized coal boiler.

5) Good load regulation performance. The circulating fluidized bed boiler load adjustment range can reach 4: 1, and the load adjustment speed can reach 5~8%BMCR/ min.

ZOZEN circulating fluidized bed boiler products are divided into DHX series circulating fluidized bed steam boiler, SHX series circulating fluidized bed steam boiler, SHX series circulating fluidized bed hot water boiler, with a capacity of 10-100 tons.