Method for producing a homogeneous biomass fuel for gasification applications

Abstract

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.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims benefit of co-pending U.S. Provisional Patent Application No. 60 / 785,933, filed Mar. 24, 2006, entitled METHOD TO PRODUCE A HOMOGENEOUS BIOMASS FUEL FOR GASIFICATION APPLICATIONS, and commonly assigned to the assignee of the present application, the disclosure of which is incorporated by reference in its entirety herein.FIELD OF THE INVENTION [0002] The present invention relates to the production of a homogenous gasifier fuel feedstock with uniform gasification characteristics from a number of biomass sources which each source exhibits differences in their drying, pyrolysis, devolatization or gasification characteristics. BACKGROUND OF THE INVENTION [0003] Gasification processes convert carbon-containing solids or liquids into combustible gases that ideally contain all the energy originally present in the feed. In reality this is not easily achieved, although with good thermal management it is possible to operate ...

AI Technical Summary

Benefits of technology

[0009] The preparation 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, while maintaining the gasifier throughput rate and thermal profile. 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. The method allows for large variations in the ratios of biomass components. The method also allows fuels which may otherwise be problematic, for example due to ash content, to be blended with biomasses which do not exhibit the same issue to produce a fuel which can then be readily used.

Problems solved by technology

In reality this is not easily achieved, although with good thermal management it is possible to operate with energy efficiencies in excess of 90%.

These different gasification behaviors, coupled with different physical structures, have caused difficulties for gasifier designers in that design modifications are required for almost every type of biomass utilized.

On a wet basis this value can be substantially less and can even be less than zero, indicating that the fuel is not capable of burning in a sustainable manner while liberating energy.

The low energy density, its low packing density and difficulty in handling make the economics of transporting biomass large distances unfeasible.