High pressure compressor and steam explosion pulping method

Abstract

A steam explosion pulping method including: impregnating a cellulosic biomass feed material in a pressurized reactor vessel; discharging the impregnated feed material from the vessel to a high pressure compressor; elevating a pressure of the feed material in the compressor; discharging the pressurized feed material from the compressor to a conduit coupled to a blow valve; rapidly reducing pressure of the pressurized feed material as the feed material passes through the blow valve, and pulping the feed material by expansion of fluid in the feed material during the rapid pressure reduction.

Description

RELATED APPLICATION[0001]This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60 / 916,446 filed May 7, 2007, the entirety of which is incorporated by reference.BACKGROUND OF THE INVENTION[0002]The present invention relates to pre-treatment of cellulosic biomass feed materials, e.g., wood chips, for a steam explosion pulping. The invention relates particularly to discharging material from a digester and pressurizing a flow of steam and cellulosic material prior to steam explosion.[0003]Steam explosion pulping typically involves steam used to break apart the cellulosic fibers (explosion pulping) and has been used, for example, for enzyme hydrolysis. Pulp is produced from cellulosic biomass feed material by pressurizing feed material with steam and subsequently rapidly reducing the pressure of the feed material impregnated with the steam. The rapid pressure reduction causes steam in the cells of the feed material to expand and thereby burst the cells. Pulp...

AI Technical Summary

Benefits of technology

[0007]A steam explosion pulping method has been developed comprising: impregnating a cellulosic biomass feed material in a pressurized reactor vessel; discharging the impregnated feed material from the vessel to a high pressure compressor; elevating a pressure of the feed material in the compressor; discharging the pressurized feed material from the compressor to a conduit coupled to a blow valve; rapidly reducing pressure of the pressurized feed material as the feed material passes through the blow valve, and pulping the feed material by expansion of fluid and steam in the feed material during the rapid pressure reduction.

Problems solved by technology

The rapid pressure reduction causes steam in the cells of the feed material to expand and thereby burst the cells.

A difficulty with this approach is that it requires a large amount of steam, e.g., 500-800 lbs of steam per ton of solid feed material, to heat the material and to discharge (blow) out of the digester, which is well beyond the steam needed for pretreatment, e.g., cooking and steam impregnation, of the feed material.

The required large volume of steam is expensive in terms of energy consumption to produce.

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