Biomass gasification/pyrolysis system and process

Abstract

A system and process capable of promoting the energy content of a syngas produced from a biomass material. The system and process entail compacting a loose biomass material and simultaneously introducing the compacted biomass material into an entrance of a reactor tube, and then heating the compacted biomass material within the tube to a temperature at which organic molecules within the biomass material break down to form ash and a fuel gas mixture. The fuel gas mixture is withdrawn from the tube and the ash is removed from the tube through an exit thereof. The entrance and exit of the tube, the compaction step, and the removal step cooperate to inhibit ingress of air into the tube by forming a plug of the biomass material at the entrance of the tube and a plug of ash at the exit of the tube.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Application No. 61 / 270,393, filed Jul. 8, 2009, and is a continuation-in-part patent application of co-pending U.S. patent application Ser. No. 12 / 760,241, filed Apr. 14, 2010, which claims the benefit of U.S. Provisional Application No. 61 / 212,624, filed Apr. 14, 2009. The contents of these prior patent applications are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]The present invention generally relates to the conversion of organic lignocellulosic materials (biomass) into useful fuels (biofuels), and more particularly to a system and process capable of continuous conversion of biomass into synthesis gas (syngas).[0003]Syngas is a gas mixture containing carbon monoxide (CO) and hydrogen gas (H2) produced by the conversion of carbonaceous materials, such as coal, petroleum, and biomass materials. Though having a lower energy density than natural gas, syngas is sui...

AI Technical Summary

Benefits of technology

[0009]The present invention provides a system and process capable of efficient production of syngas from biomass materials in a manner capable of yielding energy contents of as much as 300 BTU / ft3 and higher.

[0011]According to a second aspect of the invention, the process includes compacting a loose biomass material and simultaneously introducing the compacted biomass material into an entrance of a reactor tube, heating the compacted biomass material within the reactor tube to a temperature at which organic molecules within the compacted biomass material break down to form ash and a fuel gas mixture, withdrawing the fuel gas mixture from the reactor tube, removing the ash from the reactor tube through an exit thereof, and inhibiting ingress of air into the reactor tube by sufficiently compacting the biomass material at the entrance of the reactor tube to form a plug of the compacted biomass material at the entrance and compacting the ash at the exit of the reactor tube to form a plug of the ash at the exit.

Problems solved by technology

For example, partial combustion results in poor-quality products, for example, a syngas having an energy content of 150 BTU / ft3 or less, because of the dilution of the fuel gasses by the nitrogen in the injected air and the gaseous products of the combustion.

For indirect heat transfer, it can be difficult to maintain desired heat transfer rates because the process deposits coatings on the heat transfer surfaces that act as insulating materials.

Finally, direct heat transfer with circulating solids is effective but requires complex technology because the circulating solids, which typically transfer heat between a burner and a pyrolysis reactor, involve a moving bed that requires a significant investment in equipment and energy management to be effective in a continuous process.

Because biomass is a low-energy content fuel and is dispersed geographically, low-BTU syngas negatively affects the economic payback for the gasifier system.

However, a major problem remains as to how to prevent the ingress of air while allowing the egress of syngas from the feed material ingress and the egress of ash from the spent material outlet.

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