System for the torrefaction of lignocellulosic material

Abstract

A pressurized torrefaction reactor vessel including: a rotatable shaft extending vertically down from a top of the vessel; scraper devices each at a different elevation within the vessel and mounted to the shaft; a tray associated with each one of the scraper devices such that the scraper device is immediately above a tray of the tray assembly; wherein the tray is an open mesh and impermeable to passage of biomass through the tray; each tray includes a discharge opening to transfer biomass from the tray and down to a tray of a lower one of the tray assemblies, and wherein the discharge opening in the lowermost tray assembly transfers the biomass to a pile of the biomass in the vessel, and a bottom discharge port of the vessel through which the torrefied biomass is discharged.

Description

CROSS RELATED APPLICATION[0001]This applications claims priority to U.S. Provisional Patent Application Ser. No. 61 / 502,116 filed Jun. 28, 2011, and is related to U.S. Provisional Patent Application Ser. No. 61 / 501,900 filed on Jun. 28, 2011. The entirety of these applications are incorporated by reference.BACKGROUND OF THE INVENTION[0002]The present invention generally relates to methods for torrefaction of biomass material such as lignocellulosic material including wood and other biomass, and more particularly relates to a pressurized reactor vessel for the torrefaction of such material.[0003]Torrefaction can be used to convert biomass, e.g., wood, to an efficient fuel having increased energy density relative to the input biomass. For example, wood generally contains hemicellulose, cellulose and lignin. Torrefaction removes organic volatile components from wood. Torrefaction may also depolymerize the long polysaccharide chains of the hemicellulose portion of biomass and produce a ...

AI Technical Summary

Benefits of technology

The patent describes a method of heat transfer using a gas as a heat transfer media. By increasing the pressure of the gas, the gas becomes a larger volume and can heat up faster, which makes the heat transfer more efficient. The gas flows through the material and trays, continuously heating and cooling the material in a controlled manner. This method helps to regulate the temperature of the material during the torrefaction process and improve the quality of the final products.

Problems solved by technology

A difficulty with unpressurized reaction vessels is their large size needed to handle the large volume of gas required to transfer a given amount of heat to the material to be torrefied.

The volumetric flow rate of the gas impacts the pressure drop in the bed of material, piping, heat exchangers, and thus requires larger equipment and higher energy consumption to perform the same heating duty.

Further, pressurized reaction vessels require pressurized gases and conduits for the pressurized gases.

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