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(11) | EP 0 276 145 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Peat drying apparatus and method |
(57) In drying apparatus for removing moisture from peat, hot gases generated by a furnace
4 are sucked through a rotary drum drier 1 by a downstream blower 16. Peat is fed
into the drum drier 1 by a conveyor 3 and entrained with the gas flow for direct contact
heat exchange and intensive drying action during its passage through the drier. Downstream
of the drier 1, the peat and hot gases are separated by cyclone units 8 and 14. A
substantial proportion of the hot gases separated from the gas and peat mixture are
returned by duct 17 to the upstream end of the drying system for recycling through
the drying stage. The returned gases are input to the furnace 4 by blower 6, where
they are mixed with fresh combustion gas and reheated. Oxygen content in the hot gases
leaving the system is monitored by sensor 58 and peat input to the drier 1 is only
allowed when the oxygen content is less than 12%. Temperature within the drier is
also monitored by sensor 55 and peat input only takes place when enabled by oxygen
content and also when appropriate temperature conditions prevail in the drier. A water
input 52 to the drying system is also enabled and disabled by the oxygen sensor 58,
and water injection takes place, when enabled, if drier temperature rises to an excessive
level. |