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Inhibition of Spontaneous Combustion in Low-Rank Coals

a low-rank coal and spontaneous combustion technology, applied in the direction of solid fuels, fuel additives, fuels, etc., can solve the problems of coal dust detonation, coal dust detonation, and utilities to shut down, so as to improve the net energy content of fuels and reduce self-heating of coal

Inactive Publication Date: 2015-02-05
BENETECH INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention is about a method for treating coal to reduce its risk of catching fire, caused by high levels of heat absorption. The method involves applying a low amount of a hydrocarbon emulsion to the coal, which helps to keep it cool. The coal can be freshly mined and un-dried. Additionally, the invention provides a method for waterproofing the coal to prevent water uptake, which can further reduce its risk of catching fire. The waterproofing agent can be a hydrocarbon, a hydrocarbon emulsion, a silicone, or a silane. The invention also includes a method for improving the energy content of fuel that has been exposed to rain or flooding. This method involves waterproofing the fuel to prevent water uptake, which can reduce its risk of catching fire.

Problems solved by technology

The spontaneous combustion of coal is a serious problem for utilities, both during transport and on-site handling.
In addition to the loss of fuel, attempting to handle ignited coal can initiate combustion events that lead to the detonation of coal dust, forcing utilities to shut down for weeks to months with losses from electricity generating revenue and additional costs from construction to replace the destroyed infrastructure.
However, at or near room temperature the rate of oxidation of coal is very slow.
Drying the coal, whether through natural or artificial processes, causes the coal's structure to break down.
As it dries it loses water and eventually fragments.

Method used

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  • Inhibition of Spontaneous Combustion in Low-Rank Coals
  • Inhibition of Spontaneous Combustion in Low-Rank Coals
  • Inhibition of Spontaneous Combustion in Low-Rank Coals

Examples

Experimental program
Comparison scheme
Effect test

example 1

Heat of Wetting

[0037]To examine the heat of water adsorption and determine whether a surface treatment could affect this, freshly-produced coal particles were sieved, and a fraction between 18 and 60 mesh was isolated. The coal was treated with a variety of agents and then dried at 40° C. overnight, or, in some cases, for several days. A one liter vacuum dewar flask calorimeter containing a magnetic stir bar, thermocouple, and 100 grams of deionized water was assembled and allowed to come to equilibrium. The thermocouple was attached to a data recorder sampling at one data point per second. Twenty grams of the treated coal was then added to the calorimeter with stirring and the thermocouple was used to vigorously mix the coal into the water insuring complete wetting over a period of five to ten seconds. The temperature of the water and coal mixture was monitored and after between five and twenty minutes the temperature was extrapolated back to the point at which the coal was added. ...

example 2

Perk Tests

[0040]Approximately 30 kg of <5.08 cm coal was treated with the indicated treatment (see Table 2), divided into three approximately equal portions and allowed to dry for four days. All treatments added a total of approximately 4% by weight of water solution to the coal. The portions were divided in four and each portion in four parts was loaded into a separate tared 15.25 cm diameter translucent schedule 40 PVC tube that was closed at one end with a cotton cloth. The combined sample plus tube was re-weighed and the weight recorded. The coal filled the tube to a depth of 61 to 66 cm. Approximately 8.8 kg of water were poured into the top of the tube and the time it took to run out was recorded. The tube was then re-weighed and the coal was poured out of the tube and examined. In spite of the large amount of water that was poured through the coal sample, the majority of the mineral oil emulsion treated coal was still dry. The experiment was repeated five days later, that is,...

example 3

Large-Scale Test

[0044]Approximately 75,000 short tons of freshly mined Powder River Basin (PRB) coal were treated at an average rate of 0.8 lbs of coal tar per ton (330 grams per metric ton) using a coal tar emulsion. During the application, and subsequent to it, the coal was subjected to 43-63 cm of rain as it was treated then transported via open barge to an ocean freighter. On loading the average coal temperature was 33° C. During transport across the Atlantic Ocean, the ship's captain pumped off 700 short tons of water from the hold, indicating that the treated coal was shedding surface water. This was an unusual occurrence—generally coal will not shed water during transport. Upon unloading the average coal temperature was 31° C. It was clear that in addition to shedding water the coal had not experienced self-heating. The coal was stacked out at the receiving dock and the temperature was monitored for five days:

TABLE 4Temperature of Stacked-Out Treated CoalTreated coalCompariso...

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PUM

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Abstract

A method for treating coal to reduce spontaneous combustion by reducing an exothermic heat of adsorption after the coal has begun to dry and when the coal is subsequently exposed to a liquid water is described. A source of a fluid pressure of a diluted hydrocarbon mixture is provided. A hydrocarbon in the mixture is a hydrocarbon emulsion of mineral when the coal is subsequently exposed to a liquid water oil, fuel oil, asphalt, or coal tar emulsions. A volume of the diluted hydrocarbon mixture is applied to a stream of freshly-mined and undried coal to provide a water-proofing of the coal to prevent water uptake after exposure to precipitation or flooding during transport and storage of the coal. The treated coal is loaded into a bulk pile. A temperature change trend in the bulk pile is reversed wherein a temperature of the bulk pile trends towards an ambient temperature rather than trending to a temperature higher than the ambient temperature.

Description

TECHNICAL FIELD[0001]The invention relates to coal mining as well as transport and storage of coal, and more particularly, the invention relates to a method for treating coal to reduce or prevent spontaneous combustion by reducing the exothermic heat of adsorption after the coal has begun to dry and when the coal is subsequently exposed to liquid water.BACKGROUND OF THE INVENTION[0002]The spontaneous combustion of coal is a serious problem for utilities, both during transport and on-site handling. In addition to the loss of fuel, attempting to handle ignited coal can initiate combustion events that lead to the detonation of coal dust, forcing utilities to shut down for weeks to months with losses from electricity generating revenue and additional costs from construction to replace the destroyed infrastructure.[0003]The problem of spontaneous combustion has been recognized for many decades. U.S. Pat. No. 2,184,621 (Marmaduke, 1938) cites coal's ability to spontaneously ignite and pro...

Claims

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Application Information

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IPC IPC(8): C10L5/04C10L10/02
CPCC10L5/04C10L2290/20C10L2290/08C10L10/02C10L9/10C10L2200/0272C10L2200/0438C10L2230/08C10L2230/14C10L2250/08C10L2290/18
Inventor WOLFF, ANDREW R.BLAZEK, CHRISTOPHER F.SUCH, MICHAEL T.
Owner BENETECH INC
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