Fuel preparation apparatus and method

Abstract

An apparatus and method for fuel preparation for example by milling and drying to produce a pulverous fuel supply are described. The apparatus includes a fuel preparation unit adapted to receive a mixture of fuel and a gas and to prepare the fuel for combustion in a pulverous state; an output conduit defining an output flow path for a mixture of pulverous fuel and gas from the fuel preparation unit; a phase separator disposed to receive the mixture from the output conduit and to separate the mixture into a gas phase comprising at least a major part of the gas from the mixture and a fuel phase comprising the pulverous fuel; a gas phase conduit defining a flow path for the gas phase from the separator; a heat exchanger preferably being a process fluid heat exchanger such as a feed water heat recovery heat exchanger fluidly connected to the gas phase conduit and adapted to receive and dry the gas phase. The method applies the principles embodied in the apparatus.

1 . An apparatus for preparation and drying of a fuel to produce a pulverous fuel supply comprising:
 a fuel preparation unit adapted to receive a mixture of fuel and a gas and to prepare the fuel for combustion in a pulverous state;   an output conduit defining an output flow path for a mixture of pulverous fuel and gas from the fuel preparation unit;   a phase separator disposed to receive the mixture from the output conduit and to separate the mixture into a gas phase comprising at least a major part of the gas from the mixture and a fuel phase comprising the pulverous fuel;   a gas phase conduit defining a flow path for the gas phase from the separator;   a heat exchanger fluidly connected to the gas phase conduit to receive and dry the gas phase.   
     
     
         2 . An apparatus in accordance with  claim 1  wherein the fuel preparation unit is a mill adapted to receive a mixture of fuel and a gas and to mill the fuel to a pulverous state. 
     
     
         3 . An apparatus in accordance with  claim 1  wherein the heat exchanger is a process fluid heat exchanger. 
     
     
         4 . An apparatus in accordance with  claim 1  wherein the heat exchanger is a heat exchanger disposed to exchange heat with a process fluid and supply the same for use in an industrial process. 
     
     
         5 . An apparatus in accordance with  claim 4  wherein the heat exchanger is adapted to supply the process fluid to an industrial process in such manner as to make use of the sensible heat therein. 
     
     
         6 . An apparatus in accordance with  claim 4  wherein the process fluid is feedwater for a steam generator. 
     
     
         7 . An apparatus in accordance with  claim 1  wherein the phase separator is adapted to separate substantially all of the gas output from the mill is separated into the gas phase, 
     
     
         8 . An apparatus in accordance with  claim 1  further comprising a fuel source and a gas source together configured to supply a mixture of fuel and gas to the mill. 
     
     
         9 . An apparatus in accordance with  claim 8  wherein the gas source supplies a gas at elevated temperature. 
     
     
         10 . An apparatus in accordance with  claim 9  wherein the gas source comprises a source of optionally preheated air and a supply of flue gas from a combustion chamber. 
     
     
         11 . An apparatus in accordance with  claim 8  wherein fuel source comprises a supply of a low-rank fuel with a moisture content of at least 25% on average. 
     
     
         12 . An apparatus in accordance with  claim 1  further comprising a storage volume and a supply conduit to receive the fuel phase and supply the fuel phase to the storage volume. 
     
     
         13 . An apparatus in accordance with  claim 1  further comprising a steam generator and a supply conduit to receive the fuel phase and supply the fuel phase to the steam generator. 
     
     
         14 . An apparatus in accordance with  claim 13  wherein the supply conduit is configured to supply the fuel phase directly to one or more burners of the steam generator. 
     
     
         15 . An apparatus in accordance with  claim 14  wherein the supply conduit is configured to supply the fuel phase to a storage silo of a steam generator. 
     
     
         16 . A method of preparation of a fuel to produce a pulverous fuel supply comprising the steps of:
 supplying a mixture of fuel and a gas to a fuel preparation unit adapted to prepare the fuel for combustion in a pulverous sate;   outputting from the fuel preparation unit a mixture of pulverous fuel and gas;   separating the mixture into a gas phase comprising at least a major part of the gas output and a fuel phase comprising the pulverous fuel;   passing the gas phase to a heat exchanger to dry the gas phase.   
     
     
         17 . A method in accordance with  claim 16  applied as a method of milling and drying of a fuel to produce a pulverous fuel supply, in that the fuel preparation unit is a mill applied to receive a mixture of fuel and a gas and to mill the fuel to a pulverous state. 
     
     
         18 . A method in accordance with  claim 16  wherein the heat exchanger is a process fluid heat exchanger. 
     
     
         19 . A method in accordance with  claim 16  wherein the heat exchanger is a heat exchanger disposed to exchange heat with a process fluid for use in an industrial process and the method comprises using the heat exchanger to effect condensation of the water vapour and thereby recover at least some of the latent heat from the drying process. 
     
     
         20 . A method in accordance with  claim 19  comprising the further step of using the process fluid in an industrial process in such manner as to make use of the sensible heat recovered in the heat exchanger. 
     
     
         21 . A method in accordance with  claim 20  wherein the process fluid is feedwater for a steam generator and the step of using the process fluid in such manner as to make use of the sensible heat recovered in the heat exchanger in that the sensible heat recovered in the heat exchanger effects preheating of the feedwater. 
     
     
         22 . A method in accordance with  claim 16  wherein substantially all of the water vapour laden gas output from the mill is separated into the gas phase and diverted away to the heat exchanger. 
     
     
         23 . A method in accordance with  claim 16  wherein the step of supplying a mixture of fuel and a gas to a mill comprises the supply of a gas at elevated temperature. 
     
     
         24 . A method in accordance with  claim 23  wherein the step of supplying a gas at elevated temperature comprises the supply of a mixture of optionally preheated air and flue gas from a combustion chamber. 
     
     
         25 . A method in accordance with  claim 16  wherein the step of supplying a mixture of fuel and a gas to a mill comprises the supply of a low-rank fuel with a moisture content of at least 25%. 
     
     
         26 . A method in accordance with  claim 16  comprising a method of producing a pulverous fuel supply for a steam generator such as a boiler for example of a thermal power plant. 
     
     
         27 . A method in accordance with  claim 26  further comprising the additional step of supplying the fuel phase to the steam generator. 
     
     
         28 . A method in accordance with  claim 27  further comprising the additional step of supplying the fuel phase directly to one or more burners of the steam generator. 
     
     
         29 . A method in accordance with  claim 28  further comprising the additional step of supplying the fuel phase to a storage silo of a steam generator. 
     
     
         30 . A method in accordance with  claim 16  comprising the further step of passing the fuel phase for storage.