Method for producing a homogeneous biomass fuel for gasification applications
A method for producing a gasifier feedstock with uniform gasification characteristics from a number of biomass sources which each exhibit differences in their drying, pyrolysis, devolatization or gasification characteristics. The method allows biomass from a wide range and sources and with a wide range of gasification characteristics to be utilized within a gasifier without modification of the gasifier unit. The method produces a fuel pellet with controllable size, density and moisture content. The method smoothes any changes in calorific value which may exist between different feedstocks. It has been found that the gasification characteristics of a pellet formed in this way is strongly dependant upon the shape, moisture content and density of the pellet formed and less sensitive to the origin of the biomass feedstock.
1 ) A method for producing a homogeneous gasifier fuel from a plurality of different biomasses, wherein each biomass exhibits differing drying, pyrolysis, devolatization or gasification characteristics, comprising:
a) drying each type of biomass to a moisture content in the range of from about 0% to about 50%;
b) reducing the characteristic length of the biomass particles to the range of from about 0.01 inches to about 0.1 inches;
c) combining and mixing the different types of biomass together;
d) densification of the biomass to produce a solid with a characteristic length in the range of from about 1 cm to about 5 cm;
e) densifying the biomass such that the particles contains a voidage fraction less than about 25%; and,
f) feeding the pellet into a suitable gasification designed for the size, shape, void fraction and moisture content of a fuel described in a) through e) above.
2 ) The method of claim 1 , wherein a binding agent is added prior to densification to aid in particle coagulation.
3 ) The method of claim 1 , wherein a cubic structure is formed with a characteristic length in the range of about 0.5 cm to about 8 cm.
4 ) The method of claim 1 , wherein a cubic structure is formed with a characteristic length in the range of about 1 cm to about 3 cm.
5 ) The method of claim 1 , wherein a cylinder-like structure is formed having a characteristic diameter of from about 0.1 cm to about 3 cm and having a characteristic length of from about 0.5 cm to about 3 cm.
6 ) The method of claim 1 , wherein a cylinder-like structure is formed with a characteristic diameter of from about 0.2 cm to about 1 cm and having characteristic length of from about 0.6 cm to about 1.2 cm.
7 ) The method of claim 1 , wherein the biomass is steam treated to improve the compaction qualities of the cellulostic matter.