Method for reducing adhesion of ash in boiler and device for the same

Abstract

A device for reducing ash adhesion in a boiler, includes: a calculator ( 9 ) which, in the case of mixing one or more types of solid fuels, calculates and determines the mixing ratio of the solid fuels so that the resultant solid fuel mixture has a slag viscosity not lower than a reference value at a predetermined atmospheric temperature; and fuel supply amount regulators ( 3 a, 3 b ) which regulate the amount of the solid fuels to be supplied to the boiler based on the mixing ratio as described above. By using this device, ash adhesion in a boiler can be easily and accurately predicted and, therefore, ash adhesion can be reduced even in the case of using various types of solid fuels including a low-grade coal as fuel.

1 . A method for reducing adhesion of ash in a boiler, comprising:
 determining, when one or more types of solid fuels are mixed, a mixing ratio of each solid fuel calculated so as to obtain a resultant solid fuel mixture having a slag viscosity that matches or exceeds a reference value at a predetermined atmospheric temperature, and   supplying the solid fuels mixed based on the mixing ratio as fuel to the boiler.   
     
     
         2 . The method for reducing adhesion of ash in a boiler according to  claim 1 , wherein the slag viscosity is calculated based on a composition of ash components in the resultant solid fuel mixture. 
     
     
         3 . The method for reducing adhesion of ash in a boiler according to  claim 1 , wherein the slag viscosity is calculated based on a result of measuring a slag viscosity of slag formed by heating ash of each solid fuel at the predetermined atmospheric temperature. 
     
     
         4 . The method for reducing adhesion of ash in a boiler according to  claim 1 , wherein the reference value is a value of the slag viscosity which is, with reference to a relationship between the slag viscosity of each solid fuel at the predetermined atmospheric temperature and ash deposition ratio, associated with the ash deposition ratio of a predetermined value or lower. 
     
     
         5 . The method for reducing adhesion of ash in a boiler according to  claim 4 , wherein the reference value lies between 300 and 1000 Pa˜s which are values of the slag viscosity associated with the ash deposition ratio of 5˜7% or lower. 
     
     
         6 . The method for reducing adhesion of ash in a boiler according to  claim 1 , wherein the predetermined atmospheric temperature is an atmospheric temperature in a region close to a burner for burning each solid fuel. 
     
     
         7 . The method for reducing adhesion of ash in a boiler according to  claim 1 , wherein the predetermined atmospheric temperature is a highest atmospheric temperature allowed by boiler design. 
     
     
         8 . A device for reducing adhesion of ash in a boiler, comprising:
 a calculating means which determines, when one or more types of solid fuels are mixed, a mixing ratio of the solid fuels calculated so as to obtain a resultant solid fuel mixture having a slag viscosity that matches or exceeds a reference value at a predetermined atmospheric temperature, and   a fuel supply amount regulating means which regulates an amount of each solid fuel supplied to the boiler based on the mixing ratio.   
     
     
         9 . The device for reducing adhesion of ash in a boiler according to  claim 8 , wherein the slag viscosity is calculated based on a composition of ash components in the resultant solid fuel mixture. 
     
     
         10 . The device for reducing adhesion of ash in a boiler according to  claim 8 , wherein the slag viscosity is calculated based on a result of measuring a slag viscosity of slag formed by heating ash of each solid fuel at the predetermined atmospheric temperature. 
     
     
         11 . The device for reducing adhesion of ash in a boiler according to  claim 8 , wherein the reference value is a value of the slag viscosity which is, with reference to a relationship between the slag viscosity of each solid fuel at the predetermined atmospheric temperature and an ash deposition ratio, associated with the ash deposition ratio of a predetermined value or lower. 
     
     
         12 . The device for reducing adhesion of ash in a boiler according to  claim 11 , wherein the reference value lies between 300 and 1000 Pa·s which are values of the slag viscosity associated with the ash deposition ratio of 5˜7% or lower. 
     
     
         13 . The device for reducing adhesion of ash in a boiler according to  claim 8 , wherein the predetermined atmospheric temperature is an atmospheric temperature in a region close to a burner for burning each solid fuel. 
     
     
         14 . The device for reducing adhesion of ash in a boiler according to  claim 8 , wherein the predetermined atmospheric temperature is a highest atmospheric temperature allowed by boiler design.