Coal pulverizing systems for power generation
The pulverized coal-fired boiler for power generation is a mature technology which requires the production of fine coal for combustion. The product material particle size is smaller than 250 microns and about 70 percent smaller than 75 microns. It is no coincidence that most of the new coal technologies for combustion or gasification require a product with a similar particle size distribution for complete reaction. This particle size distribution provides coal particles which can react with oxygen in the air at local velocities and resident times in the boiler furnace to result in almost complete combustion or gasification with 1 or 2 percent carbon loss in the resulting ash. Size reduction, while being one of the most common unit operations on material is also one of the least understood, requiring a high energy input. When pulverizing coal of the particle size required there is an added complication that the product may spontaneously ignite, particularly if the process passes through a stage when an explosive or at least highly combustible mixture of fine coal and air is present. The pulverized coal system covers that portion of the power station from coal bunkers to feeders, pulverizers and delivery system to the boiler burner or gasifier injection point. The transport medium has traditionally been air and in some cases inert gases. The system has usually been lean phase with air to coal ratios in excess of 1:4:1. More recently, a few systems have been dense phase with air to coal ratios of 1:30 up to 1:100. This has the distinct advantage of reduced transport pipe diameter. The key element in the system, the coal pulverizer, will be considered first.
- OSTI ID:
- 68667
- Report Number(s):
- CONF-9309459-; TRN: 95:003610-0015
- Resource Relation:
- Conference: Technical seminar of the Asia-Pacific Economic Cooperation (APEC) Experts` Group on Clean Coal Technology, Chiang Mai (Thailand), 6-10 Sep 1993; Other Information: PBD: 1993; Related Information: Is Part Of APEC experts` group on clean coal technology; PB: 546 p.
- Country of Publication:
- United States
- Language:
- English
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