Issues regarding coal quality for circulating fluidized beds in chemical enterprises
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Technologies such as Texaco are used in the methanol production process involving the use of gas as a raw material; for driving the air separation units in these systems, turbines are generally employed. The performance of these turbines depends on the parameters and quality of the steam used. When selecting coal for boilers, some suggest using coal with a lower calorific value, while others argue that higher calorific value coal should be chosen to ensure stable operation of the process system. Please analyze which is right and which is wrong?
It is certainly necessary to take cost into consideration; good coal is expensive, but for fluidized bed systems, it’s not a problem to use coal of slightly lower quality
Circulating fluidized beds have high requirements for coal quality: the particles should be small in size, low in density, spherical in shape, and have good fluidity. But it seems there is no requirement regarding calorific value; I think the calorific value should be determined based on the actual production conditions.
It seems the original poster has gotten the order wrong; one should first determine the type of coal, and then choose the boiler type based on that coal type. How can one choose the type of coal based on the boiler? The characteristic of circulating fluidized bed boilers is their wide adaptability to different types of coal – they can handle both low-quality and high-quality coals. From an economic perspective, it is recommended to use coal with a calorific value of 3500 Kcal/kg; in this case, the volatility of the coal needs to be taken into consideration
The greatest advantage of circulating fluidized bed boilers is their wide fuel adaptability
The greatest advantage of circulating fluidized bed boilers is their wide fuel adaptability; they are particularly suitable for burning coal with low calorific value, such as coal gangue and low-quality bituminous coal. These boilers feature low combustion temperatures, high combustion efficiency, and low emissions of oxides of nitrogen (less than or equal to 200 mg/Nm3)； By using limestone addition for desulfurization, the desulfurization efficiency can exceed 90%, which constitutes clean combustion. The coal particles entering the furnace are smaller than 8 mm in size, while the limestone powder particles are smaller than 1 mm. The technology for large-scale (300 MW and above) circulating fluidized bed boilers in China was introduced from Alstom in France; the first demonstration unit in the country was installed at the Baima Power Plant in Sichuan, and it is currently operating well.
The greatest advantage of circulating fluidized bed boilers is their wide fuel adaptability; even lower-quality coal poses no problem
The calorific value isn’t an issue; as long as the boiler can steadily supply qualified steam, that’s all that matters! A fluidized bed can burn even coal gangue – what more could one ask for! !
The parameters of steam are not determined by the quality of coal; it is completely fine to use coal of lower quality during design. We have previously built a CFB boiler that used waste materials as fuel, and there were no issues with that either. In China, there are over 2,000 CFB boilers that utilize our technology.