Methods of drying biomass and carbonaceous materials

a technology of carbonaceous materials and biomass, which is applied in the direction of drying, waste based fuel, lighting and heating apparatus, etc., can solve the problems of degrading biomass materials, increasing energy prices outpacing the efficiency of these drying processes, and affecting the economic and technical benefits of power generation, so as to reduce thermal energy and cost, and uniform chemical and physical properties

Inactive Publication Date: 2013-12-12
GTL ENERGY LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010]The invention provides methods of processing porous materials, such as biomass and carbonaceous materials, to decrease the thermal energy and cost required to dry the material to a specified level. In addition, the invention treats mixtures of particulate biomass and carbonaceous materials to form low-moisture, compacted products that possess uniform chemical and physical properties.

Problems solved by technology

But mixtures of biomass and coal often contain too much moisture to be economically and technically useful for power generation.
Even with improvements gained by more sophisticated designs, the rising price of energy has outpaced the efficiency of these drying processes, as applied to raw fuel materials.
This type of drying system is usually thermally efficient but can degrade the biomass material because of the high temperatures involved.
This system can also create conditions that lead to fires and explosions.
Direct drying systems are seldom used for drying coal because of the dangers created in bringing volatile coal into contact with high temperature gas.
However, indirect drying systems require larger equipment to account for the lower drying rate created by relatively temperate drying conditions.
The associated costs of this energy as well as environmental controls significantly add to overall manufacturing costs.
Low-rank coal and other carbonaceous materials are difficult to dry because of the unfavorable physical and thermal properties of coal.
The process is inefficient because coal is a good thermal insulator that resists heat transfer.
Thus, large amounts of energy are required to generate sufficient heat to dry a low-rank coal that has a low energy density.

Method used

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  • Methods of drying biomass and carbonaceous materials
  • Methods of drying biomass and carbonaceous materials
  • Methods of drying biomass and carbonaceous materials

Examples

Experimental program
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Effect test

example 1

[0082]Samples of pine, red oak and PRB coal, and Brown Coal (coal from LaTrobe Valley, Australia) were processed to confirm the efficiency and performance of mechanical compaction to remove liquid water. The samples were prepared to sizes and shapes believed to be advantageous for compaction. Each material, including a mixture of pine and PRB coal, were subjected to up to 40,000 lb / in2 pressure. Expressed water was collected. All materials were weighed and assayed for moisture content. All compaction tasks were conducted at ambient temperature.

[0083]Raw materials (unprocessed material) and compacted products were dried at about 104° F. on a laboratory moisture determination device to ascertain the relative drying rates of each sample. Results are summarized in Table 1, and plotted in FIGS. 4-9. Graphics were added to FIG. 4 that show the moisture removed by compaction and the reduction in drying time required to achieve an equal moisture content. In this case, compaction removed abo...

example 2

[0093]Industry requires briquettes to resist breakage during handling and storage. Sometimes briquettes made exclusively from low-rank coal are brittle or lack strength to satisfy industry's requirements. In this example, a mixture consisting of low-rank coal and pine wood was prepared and processed by the present invention. Results confirm that the physical properties of briquettes made from this mixture were superior to those made exclusively from low-rank coal.

[0094]The first series of tests measured the compressive strength of briquettes that contained various proportions of low-rank coal and pine wood (biomass). Both materials were milled to pass about a 2.4 mm screen opening. Table 3 demonstrates that increasing the proportion of biomass increases compressive strength, a measure of the ability to bear weight without breaking. Observations have concluded that biomass provides additional strength by making the briquette slightly flexible, thus able to bend with the load without ...

example 3

[0097]There is an incentive to reduce greenhouse gas (GHG) emissions created by burning fossil fuels, especially low-rank coal. Government agencies including the United States EPA, publishes the carbon dioxide emission factor for low-rank coal (lignite) is 4,600 lb / st lignite fired. The emission factor for wood, the type of biomass used in the examples presented for the present invention, is 3,400 lb / st wood fired. The carbon dioxide produced by combusting wood, a renewable resource, is not considered a GHG. Briquettes formed from a mixture of low-rank coal and biomass therefore has the advantage of producing less GHG for any given amount of energy produced by combustion. Carbon dioxide emissions are reduced approximately in proportion to the amount of biomass included in the briquette. For example, a briquette formed as described in these Examples, containing about 20 wt % biomass, will reduce GHG emissions by approximately 20%.

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Abstract

The invention provides methods of reducing the energy required to remove moisture from biomass, carbonaceous materials and mixtures of the same. The method significantly reduces the energy requirements by removing moisture as a liquid and by transferring the moisture to the surface of the material where it is more easily and efficiently evaporated.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 61 / 423,558 filed Dec. 15, 2010, which is incorporated herein by reference.TECHNICAL FIELD[0002]The invention relates to methods of reducing the moisture content of materials including biomass, such as woody materials, grasses, agricultural plants, and residues, and mixtures thereof and carbonaceous materials such as bituminous coal, subbituminous coal, lignite, brown coal, peat, waste coal and mixtures thereof.BACKGROUND OF INVENTION[0003]Biomass and low-rank coals contain high levels of moisture, which must be removed before they are commercially useful as a source of fuel, or as a manufactured product. Low-rank coal is typically used for power production in close proximity to where it is found because its low energy density would likely be offset by any energy expended to ship such low-rank coals any appreciable distanc...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C10L5/08
CPCC10L5/08C10L5/361C10L5/442F26B5/08Y02E50/30F26B2200/02F26B2200/24Y02E50/10F26B5/14
Inventor FRENCH, ROBERTREEVES, ROBERT A.
Owner GTL ENERGY LTD
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