System and Method for Renewable Fuel Using Sealed Reaction Chambers

Abstract

The system and method described herein provide for the higher production rate fractionation of biomass for the purpose of selectively separating specific volatile components, which may subsequently be used in the production of a renewable liquid fuel, such as gasoline. Increased production rates of processing of biomass or other feedstock is achieved through the use of sealed reaction chambers, which may be transferred in a sealed configuration between stations in a multi-station processing system. Also, the present invention considers the use of piston assemblies for the dual functions of controlling fluid intake and exhaust (in combination with valves) and for providing a more robust and more cost effective sealing mechanism. The present invention may also achieve improved uniformity of biomass processing through the introduction of a mechanical agitator designed to mix the biomass during processing.

Description

RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 13 / 687,449, filed Nov. 28, 2012, and claims the benefit of the following U.S. Provisional Patents Applications: Ser. No. 61 / 564,194, titled “System and Method for Producing Renewable Fuel Using Sealed Cartridges” filed Nov. 28, 2011; Ser. No. 61 / 564,195, titled “System and Method for Producing Renewable Fuel Using Stationary Pressure Chambers” filed Nov. 28, 2011; Ser. No. 61 / 569,058, titled “System and Method for Producing Renewable Fuel Using Sealed Cartridges” filed Dec. 9, 2011; and Ser. No. 61 / 569,053, titled “System and Method for Producing Renewable Fuel Using Stationary Pressure Chambers” filed Dec. 9, 2011. All of these applications are hereby incorporated by reference herein.BACKGROUND[0002]1. Field of Invention[0003]The invention relates to a system and method of using stationary pressure chambers and sealed cartridges to produce renewable fuel from biomass.[0004]2. Discussion...

AI Technical Summary

Benefits of technology

[0014]The system and method described herein provide for the higher production rate fractionation of biomass for the purpose of selectively separating specific volatile components, which may subsequently be used in the production of a renewable liquid fuel, such as gasoline. Increased production rates of processing of biomass or other feedstock may be achieved through the use of sealed reaction chambers according to various embodiments of this invention. In one embodiment, this goal may be achieved through the use of cartridges which may be sealed once assembled, and which may be transferred between stations in a multi-station processing system, while preserving the fluidic environment surrounding the biomass during the transfer between processing stations. Also, a piston-cylinder assembly may be utilized to provide the multiple functions of pressure control, the intake of a working gas and the extraction of fluids produced. Improved uniformity of biomass processing may also be achieved through the introduction of a mechanical agitator designed to mix the biomass during processing.

[0015]Agitation can provide several benefits to the biomass conversion process. When rapidly stirring a solid in a fluid environment, the particles can be separated, exposing much higher surface area levels of the biomass to the working fluid. In addition, the relative motion of the fluid environment and the biomass may create higher fluid flows over the biomass, again helping to draw out volatile components. Agitation and mixing may help to homogenize the mixture's temperature, which may be important to ensuring that the volatile compounds produced are of a consistent and usable composition. Additionally, the mixing action itself may continue to break down and pulverize the biomass materials, in particular breaking down the largest particles which might otherwise not effectively volatilize compounds at their core.

[0016]The combination of these rate-accelerating factors along with removal of layer-thickness requirements enables a substantially higher mass flow rate of solid biomass may be processed, and a substantially higher mass flow rate of volatile compounds may be produced from a given physical size of apparatus, reducing the capital costs of equipment per unit of renewable fuel that may be produced.

[0020]The seals in prior tray systems were maintained by flexible bellows sealing to the top of the trays, which can be problematic from the standpoint of mechanical reliability, particularly in an environment with volatile organic chemicals circulating supercritical fluids and high pressure differentials. The present invention considers the use of piston assemblies for the dual functions of controlling fluid intake and exhaust (in combination with valves) and for providing a more robust and more cost effective sealing mechanism.

[0021]In embodiments where a cartridge may be used to transfer materials from station to station, the flow of fluid into the cartridge may be controlled by valved ports, which may be fully sealed during transfer between stations. The cartridge as a whole may be indexed between processing stations in a sealed configuration, eliminating a series of sealing and working fluid control issues.

Problems solved by technology

These state-of-the-art methods specifically referenced above overcame a significant challenge of traditional pyrolysis, which had been that in heating biomass in large batches over broad ranges of temperatures, a wide variety of gaseous and liquid compounds were produced in forms that were of mixed composition, and were therefore difficult to further process to make renewable fuels.

This process had been further complicated by the thousands of compounds in biomass feedstock, by the fact that the products of pyrolysis are often not thermodynamically stable, and by the fact that it had been difficult to consistently maintain narrow ranges of pressure and temperature in three dimensional commercial pyrolysis systems.

However, because the biomass layer must be limited to a thin layer for uniformity of heating, scaling up production quantities is more challenging that it would be for larger batches of material, and therefore requires larger, more expensive equipment and / or additional production lines.

Furthermore, because state-of-the-art methods and systems typically heat only surface of the biomass layer and the compressed nature of the biomass layer limits exposed surface area, heating and cooling remains non-uniform despite the aforementioned thickness limitations.

Another drawback of state-of-the-art methodology is that the reduced surface area created by compressing the biomass into a thin layer also decreases the surface to volume ratio, and therefore increases the time required to first heat, second produce the desired reaction products, and third diffuse the reaction products back into the fluidic environment.

Such designs have been commonly employed in small scale experimental uses, but are challenging to scale up for high volume processing.

Additionally, these bellows designs typically have flexible seals which are susceptible to failure on repetitive cycling, so while they are appropriate for short term experimental use, they present reliability challenges at a commercial production scale.

This is particularly true in an environment with supercritical fluids or volatile organic chemicals circulating, which may damage the flexible members, and is also especially true with high pressure differentials between stations, which increase the stresses on the joints in a bellows assembly.

Further complications arise in state-of-the-art methodology when moving materials from one high pressure environment to the next, as from station to station during processing.

The incorporation of such airlocks further increases cost and decreases the mechanical reliability of equipment used to execute state-of-the-art methods.

Additionally, the mixing action itself may continue to break down and pulverize the biomass materials, in particular breaking down the largest particles which might otherwise not effectively volatilize compounds at their core.

The seals in prior tray systems were maintained by flexible bellows sealing to the top of the trays, which can be problematic from the standpoint of mechanical reliability, particularly in an environment with volatile organic chemicals circulating supercritical fluids and high pressure differentials.

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