Method to feed biomass tablets and logs into burners

Abstract

This invention pertains to a novel new method and device to feed or inject cylindrical fuel elements (logs and tablets), made of biomass and other carbonaceous materials, into burners (furnaces, boilers, stoves or fireplaces) for use as fuel in combustion. The same method and device can also be used in gasification and liquefaction plants to feed cylindrical fuel elements as the feedstock for the gasification or liquefaction reactors. The use of such a method and device to feed biomass and other carbonaceous materials into burners and gasification / liquefaction reactors enhances the use of biomass as a resource for heating, generating electricity, and converting to gaseous or liquid fuels. Increased use of biomass, which is a renewable energy source, reduces the consumption of fossil fuel, and hence reduces detrimental environmental impacts of using fossil fuel including air pollution and global warming.

Description

REFERENCES CITED [0001] A. Non-Patents: (Note: Numerals in [ ] listed below correspond to the relevant non-patent literature discussed later this document.) [0002] [1] Liu, H. and Li, Y. (2000), “Compacting Biomass and Municipal Solid Wastes to Form an Upgraded Fuel”, Project Final Report submitted to U.S. Department of Energy under Contract No. DE-AC26-98FT40155, 82 pages. [0003] [2] Liu, H. (2000), “Economic Analysis of Compacting and Transporting Biomass Logs for Co-Firing with Coal in Power Plants”, Report to U.S. Department of Energy under Contract DE-AC26-98FT40155, 52 pages. [0004] [3] Li, Y. and Lin, Y. (2002), “Compacting Solid Waste Materials Generated in Missouri to Form New Products”, report to Missouri Department of Natural Resources under Contract No. 00038-1, 90 pages. [0005] [4] Liu, H. and Li, Y. (2000), “Compacting Municipal Solid Waste into Logs for Combustion at Power Plants,” Proc. of Int. Sym. on Energy Engr., Begell House, N.Y., pp. 1420-1426. [0006] [5] Li, ...

AI Technical Summary

Benefits of technology

[0046] This invention deals with a method to feed or inject cylindrical fuel elements (logs and tablets), made of biomass and other carbonaceous materials, into burners (furnaces, stoves, boilers and fireplaces) for combustion. The method takes advantage of the round shape and uniform geometry of the fuel elements in the fuel feeding (injection) process. The fuel elements are stacked inside a special feeder chamber that has a downward bottom slope, and then rolled by gravity into the burner for combustion. The feeder has a control mechanism that regulates the rate of feeding of the fuel elements into the burner. The feeder also has one-way valves or gates that allow the biomass logs and tablets to enter the burner, but prevent smoke and fire from entering the feeder. Due to the use of gravity for feeding, the feeder is simple, energy-efficient, and reliable.

Problems solved by technology

Most biomass materials, such as waste papers, forestry waste, agricultural waste and yard waste, are very bulky (loose and fluffy) when first collected.

They are costly to handle, store and transport, and cannot be burned efficiently in burners, boilers or furnaces.

Now that the concept of compacting and making biomass logs and tablets has been published for several years, it is too late for the University or anyone else to apply for a patent on the method of producing biomass logs and tablets.

However, neither the University of Missouri nor anyone else has published or invented any means or special device to feed the biomass logs and tablets into burners.

While the latter applies pressure uniformly over the flat ends of the log or tablet (uni-axial compaction), the former compacts on curved surfaces which make pressure non-uniform.

This makes it difficult to form strong briquettes without using considerable amount of binders or heat to aid in the agglomeration.

Without using binder or heat, biomass cannot be briquetted properly.

While extrusion is widely used in the chemical and food industries, it cannot be used for binderless, room-temperature agglomeration of biomass.

This is due to the fact that ordinary extruders cannot generate the high pressure required for binderless, room-temperature compaction of biomass, which is in the neighborhood of 18,000 psi [1].

Also, the extrusion process is very sensitive to the variation of raw material properties, such as moisture and particle size.

A small variation of such material properties can often cause the extruder either to clog or to fail producing acceptable products.

All these lead to high energy consumption and high cost.

However, the study found that at present there is a lack of a suitable device to feed the biomass logs and tablets into boilers, furnaces and fireplaces.

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