Water-containing solid fuel drying apparatus and drying method

A method of drying water-containing solid fuel, comprising:

• forming a fluidized bed by injecting fluidizing gas from a bottom portion of a drying vessel in which a heat transfer pipe for flowing drying gas is disposed;
• drying water-containing solid fuel injected into the drying vessel by heating the water-containing solid fuel with the drying gas;
• generating second mixed gaseous fluid that contains vapor and the fluidizing gas by removing microparticles of the water-containing solid fuel from first mixed gaseous fluid that contains the vapor evaporated from the water-containing solid fuel and the microparticles of the water-containing solid fuel;
• generating the drying gas by compressing the second mixed gaseous fluid at a compressor;
• preheating the second mixed gaseous fluid with the drying gas that has been compressed at the compressor and has higher pressure than pressure of the second mixed gaseous fluid by introducing the second mixed gaseous fluid and the drying gas into a heat exchanger, the second mixed gaseous fluid that has been preheated being supplied to the compressor;
• generating the fluidizing gas by removing moisture from water-containing fluidizing gas which flows out from the heat transfer pipe, the water-containing fluidizing gas being gas that contains the moisture formed through condensing of vapor contained in the drying gas;
• supplying the fluidizing gas to a turbine that is used as a driving source for operating the Compressor;
• forming a circulation system, in which the fluidizing gas repeatedly undergoes phase changes among initial fluidizing gas, the first mixed gaseous fluid, the second mixed gaseous fluid, the drying gas and the water-containing fluidizing gas, in this order, and the water-containing fluidizing gas is reused upon returning to the fluidizing gas;
• and
• drying the water-containing solid fuel by heating the water-containing solid fuel with latent heat of vapor contained in the drying gas and sensible heat of the drying gas.

A water-containing solid fuel drying apparatus, comprising:

• a dryer that dries water-containing solid fuel by heating the water-containing solid fuel with drying gas, the dryer including a drying vessel into which the water-containing solid fuel and scavenging gas is injected and a heat transfer pipe for flowing the drying gas, the heat transfer pipe being disposed in the drying vessel;
• a dust collector, into which the scavenging gas that has flowed out of the drying vessel is introduced in a form of first mixed gaseous fluid that contains vapor evaporated from the water-containing solid fuel and microparticles of the water-containing solid fuel, for removing the microparticles from the first mixed gaseous fluid and generating second mixed gaseous fluid that contains the vapor and the scavenging gas;
• a compressor that compresses the second mixed gaseous fluid introduced thereinto and generates the drying gas;
• a turbine that is used as a driving source for operating the compressor;
• a heat exchanger that preheats the second mixed gaseous fluid with the drying gas that has been compressed by the compressor and has higher pressure than pressure of the second mixed gaseous fluid and that supplies the second mixed gaseous fluid that has been preheated to the compressor, the heat exchanger introducing the second mixed gaseous fluid from the dust collector and introducing the drying gas from the compressor;
• a gas-liquid separating device that performs gas-liquid separation by introducing water-containing scavenging gas which flows out from the heat transfer pipe, the water-containing scavenging gas being gas that contains moisture formed through condensing of vapor contained in the drying gas, the gas-liquid separating device supplying the scavenging gas separated from the water-containing scavenging gas to the turbine;
• and
• a primary-drying heat exchanger that is disposed between the drying vessel and the gas-liquid separating device and that preheats the water-containing solid fuel before being injected in the drying vessel with the water-containing scavenging gas that flows out of the heat transfer pipe, wherein
• the scavenging gas generated by removing the moisture from the water-containing scavenging gas at the gas-liquid separating device circulates while undergoing repeated phase changes through the first mixed gaseous fluid, the second mixed gaseous fluid, the drying gas, and the water-containing scavenging gas, in this order, the water-containing scavenging gas is reused upon returning to the scavenging gas, and the water-containing solid fuel is dried by heating the water-containing solid fuel with latent heat of vapor contained in the drying gas and sensible heat of the drying gas.