Carrier vibrating fluid bed thermal dryers are typically used for coals with a larger size fraction, such as run-of-mine coal. Carrier offers vibrating fluid bed units up to 8 ft. wide x 50 ft. long with capacities up to 250 TPH in a single unit, depending on the thermal load.
Vibration significantly assists in the fluidization of sticky and/or wet coals, and helps convey larger particles that may not fluidize well and tend to settle to the bottom of the bed.
Carrier has designed drying systems for a wide range of coal types and applications including:
- Run-of-mine coal
- Filter cake
- Coal fines from a prep plant
- Steam coal
- Reclaimed waste coal
- Coking or metallurgical grade coal
- Washed & sized bituminous coal
- Subbituminous or lignite coal prepped for gasification or liquefaction processes
Carrier has developed a number of thermal coal drying systems for several types of coal and process applications. Some of these include:
- Anthracite coal for additives in the steel making industry
- Metallurgical grade bituminous coals used in making coke
- Bituminous coals used in direct steel making processes such as the “Corex” process
- Beneficiation of PRB coals
- Beneficiation of lignite coals
- Lignite coals prior to gasification or liquefaction
Types of Coal Dryers
To meet the needs of all the different grades of coal and different applications, Carrier offers several types of dryers. These include:
- Vibrating fluid bed dryers
- Conventional flash or Tornesh flash dryers
- Conventional (non-vibrating) fluid bed dryers
- Conventional (non-vibrating) fluid bed dryers with in-bed heat exchangers
Carrier system engineers take into account each of the coal types and application processes that require special considerations and/drying system features. For example, filter cake coals are very fine and typcially hold a high volume of water. Therefore, a filter cake coal dryer must be able to handle high evaporative loads and high entrainment levels in the exhaust gases. Some coals, such as lignite, are subject to spontaneous combustion and explosions. A dryer for lignite should include explosion venting, a water deluge system and possibly an inert gas or a recirculated self-inerted process gas. Conversely, anthracite coal exhibits a high ignition temperature, rendering explosion vents or a deluge system unnecessary.
Coal Dryer System Arrangements
Because Carrier’s thermal coal drying systems are custom designed for each application, there are an infinite number of arrangements and component combinations that can be provided. Some of these arrangements include:
- Systems that dry only.
- Systems that dry and cool.
- Systems that recirculate the cooling zone exhaust gas to the drying zone supply for improved efficiency.
- Systems with closed-loop recirculated process gas streams that are heated with a direct-fired process gas heater.
- Systems with closed-loop recirculated process gas streams that are heated with indirect heat.
- Systems with recirculated self-inerted process gas streams heated by direct-fired process gas heaters.
- Systems with recirculated indirect heated inert process gas streams, such as nitrogen, with in-bed heat exchangers.
For more information on Carrier coal drying systems, refer to brochure #16909.