coal mill fires

mine fires - an overview | sciencedirect topics

Coal mine fire is devouring coal seams in major coal-producing countries including China, the United States, India, and Indonesia. Many seams have been burning for decades and some for centuries. Coal fires are a natural phenomenon; however, coal mining by humans has assisted the propagation of these fires and thereby enhancing the environmental pollution (Pone etal., 2007).

The ignition of coal mine fires is of global concern as it may be attributed to significant environmental problems (Stracher and Taylor, 2004; Avila etal., 2014). Environmentally catastrophic effects from coal fires include large amounts of pollutants such as sulfur and nitrogen oxides ((NOx) acidic gases), CO2, particulate matter (PM), organic compounds, fly ash, and potentially toxic trace elements such as arsenic, mercury, and selenium (Finkelman, 2004). Coal fires have killed people, affected entire communities to abandon their homes and businesses, damaged floral and faunal habitats, and are accountable for dangerous land subsidence (Pone etal., 2007). CO2 concentrations exceed those of other gases produced by coal fires; however, CO2 concentrations are not entirely controlled by the coal itself. CO, hydrogen and the hydrocarbons, ethylene (C2H4), propylene (C3H6), and acetylene (C2H2) are monitored as coal-fire detector gases because these are released sequentially as temperature increases during heating. Consecutive temperatures (C) at which release begins in medium volatile bituminous coal are 110, 170, 240, and 300C for CO, H2, C2H4, and C3H6, respectively. Combustion occurs between 110 and 170C, and flames appear at about 200C (Kong etal., 2017).

Pone etal. (2007) found that gases emitted from coal-fire vents in the Witbank and Sasolburg coalfields consist of a complex mixture of hydrocarbons, halocarbons, greenhouse gases (GHGs), and toxic concentrations of CO, benzene, xylene, and toluene. Based on chemical analyses, they characterized these emissions under four principal groups, such as (1) aromatic compounds mostly volatile organic compounds (VOCs) (Benzene, toluene, ethylbenzene, xylenes, ethyltoluene, and trimethylbenzene), (2) aliphatic hydrocarbons (Ethane, propane, butane, pentane, propene, and ethyne), (3) halogenated hydrocarbons (dichloromethane, chloromethane, bromomethane, iodomethane, and trichloromethane), and (4) greenhouse and other gases (CH4, CO2, and CO).

Methane monitoring in underground mines is important to prevent catastrophic explosions, mine fires, loss of human life, and the venting of a potent greenhouse gas. Methane detectors typically use catalytic heat of combustion sensors or infrared sensors to detect methane (Kissell, 2006). Catalytic heat of combustion detectors are limited to concentrations of methane below 8% and oxygen above 10%. Infrared detectors measure the absorption of infrared light due to the presence of methane and while they can measure methane without the presence of oxygen, they are hindered by the presence of water vapor and dust (Kissell, 2006). Methane detectors are classified as either portable methane detectors or machine-mounted monitors. Portable methane detectors can be hand-carried tomeasure methane levels throughout the mine. Machine-mounted monitors are integrated with machine operation, where machines cannot operate without a functioning methane monitoring system to ensure safe operating conditions. Both continuous methane monitoring with machine-mounted detectors and intermittent monitoring (every 20min) with portable detectors are required by law in many countries (Kissell, 2006).

An alternate method of collecting coal-fire gas samples used by Stracher (2007) at the Centralia mine fire in Pennsylvania consisted of pumping the gas from vents and fissures with a hand or electric pump into Tedlar gas bags made by Dupont. However, this method proved inadequate because gas chromatographic analyses of samples from the same bags over a 2weeks period revealed that the bags exchanged coal-fire gas with the atmosphere (personal communication, Donald L. Blake, Rowland-Blake Group Laboratory, University of CaliforniaIrvine).

Giggenbach gas sampling bottles are used by some volcanologists to collect volcanic gas. The bottles are made from fused silica. Glenn B. Stracher has had several such bottles made by Glasscraft Scientific Glassblowing Ltd, Lower Hutt, New Zealand, but has not used these yet. The authors know of no one who has used these bottles to collect samples of coal-fire gas for analysis.

Many accidents occur in underground mines due to the sudden release of hazardous gases, roof and side falls, mine fire, inundation, etc. Therefore, the monitoring and prediction of hazards in mines are essential for improving miners safety and productivity. Therefore, it is necessary to monitor underground mines with the help of digital mines based on the Internet of things (IoT) for increasing production of coal or minerals and minimizing accidents in underground mines.

A digital mine is the simulated version of physical mine. It is the simulation of mine-inclusive machinery and equipment, as well as simulation of the production process. It is considered to be a network of models, methods, and tools supporting the entire operation of a production. Basic advantages of a digital mine are continuous and consistent data management, production management and consequent introduction of engineering methods and tools. A digital mine provides information about different faces of mines, roadways, mine mechanics, electrical facilities, mine ventilation, safety, environmental condition, and so on. It helps increasing focus on miners safety and mine productivity (www.mckinsey.com/insights/energy_resources_materials/how_digital_innovation_can_improve_mining_productivity). Digital solutions include creation of a collaborative decision environment, a facility that enables an integrated view of the mine plan and operations, leading to early identification and rectification of any bottlenecks across the value chain. Mine management seeks to add value by converting data into meaningful information and look to increase productivity by automating the actions required as a result of meaningful information. Digital mine technology helps to deploy collected information for estimating the failure probability of specific components rather than using a traditional time-based approach that reduces maintenance cost and prevents unplanned interruptions.

IoT-based digital mining can be used for information retrieval and management of information related to geological conditions, mining operations, hazard, mines environment, mines safety, etc. A digital mine helps to control and manage: (i) all equipment in underground mine; (ii) mine face and strata visualization, including diagrams showing the percentage of mineral/stone in production, shearer position, shield heights, and pressure on shields; (iii) infrastructure monitoring including electrical network, water drainage, air pressure, etc.; (iv) conveyors/belts/bunker/transportation equipment; (v) standstill monitoring for machinery and transportation equipment including conveyors, shearer, ploughs, load-haul-dump machine, etc.; (vi) mapping of mining assets position against geographical map for observation, supply, and maintenance operation; (vii) miners/transportation tracking; (viii) ventilation and production; (ix) mine hazards and safety; and (x) video integration (CCTV), event-driven video control for operators support.

A digital mine has three-dimensional (3D) visualization, 3D spatial interpolation and 3D spatial data analysis features (Jin et al., 2011). It helps create a safe and comfortable working environment. It makes for transparent management of surface and underground objects at all times and in all mining areas (Jingfang and Zongxi, 2012). The chapter enumerates the concept of IoT, the technique of digital mine creation, and the application of digital mine for real-time monitoring and viewing of mining information to manage mining operation, miners safety and training, rescue operation, etc.

Better housekeeping and keeping some firefighting equipment handy. These include dry powder fire extinguishers, water hydrants, and equipment to create high-expansion foam. Detailed descriptions of these items are available in the literature [1]. They are also often required by the Federal and State regulations [2].

Proper ventilation and dust control for conveyor belts and belt systems is equally important as face ventilation. Conveyor belts are a frequent source of mine fires and the belt fire at the Aracoma Alma mine in 2006 caused two fatalities. Following this fire, the US Mine Safety and Health Administration (MSHA) formed the Technical Study Panel on the Utilization of Belt Air and the Composition and Fire Retardant Properties of Belt Materials in Underground Coal Mining that recommended, among other findings, the following[4]:

If belt air is used to ventilate a working section, an atmospheric monitoring system (AMS) must be utilized to monitor the air quality in the belt entry with CO and smoke sensors. This is codified in 30 CFR 75.350351.

Belt air flow away from the face is preferred because it permits the mine operator to apply rock dust to belt entries while miners are working in the face area. Also, in the event of a belt fire, smoke and fire gases travel toward the return rather than to the face.

For belt dust control, belts should be equipped with water spray systems at the loading and discharge points. Scrapers should be installed and maintained to keep the belt clean and to reduce the formation of dust to a minimum. All belt runs must be frequently inspected for proper alignment to avoid rubbing on the structure.

Carbondale (Figures 25.1.1, 25.1.6) was the first location in the anthracite region to have underground mining. Experimental digging was started in 1812. A mine fire was discovered on the west side of town in 1946. Located in the northern part of the Northern Field, the syncline there is approximately 23miles wide, and the fire occurred on the northern limb. The fire may have started as much as 5 years earlier, when the city was using the abandoned mine pits of the Hudson Coal Companys Powderly Mine as a refuse dump. Because the fire was on the extreme edge of town, the City of Carbondale and the US Bureau of Mines made only modest efforts to control the burning. Water was used to flush the fire, and 80,000 cubic yards of silt were poured into test boreholes (Munley, 1998).

Then, in 1952, the death of an elderly couple from carbon monoxide poisoning far from the supposed fire site convinced the town that it had a much larger problem. The Carbondale city government and Hudson Coal Company both sought more federal aid. New tests revealed that the fire now covered 120 acres and was burning to a depth of 100ft. Experts believed it would be impossible to cut off the fires source of oxygen and smother it. Residents were constantly monitored for carbon dioxide, and fire-caused subsidence threatened homes and the citys water system. At the time, the federal government only allocated $200,000 per year to fight mine fires, not nearly enough to handle a disaster the size of Carbondales (Munley, 1998).

In 1956, Carbondales mayor and members of the Carbondale Redevelopment Authority attended a 2-day conference in Scranton on the newly created Federal Urban Renewal Program. Although designed for slum clearance, the Carbondale fire was accepted as an urban renewal project, with potential as a model for other efforts. Workers dug a series of trenches from 60 to 100ft deep and three times as wide, removed the coal that was sold to help fund the project, and then replaced the earth after the burning material was extinguished. When the project was finished in 1972, $2,326,000 had been spent and 4 million cubic yards of earth removed. Two schools and 450 homes had to be destroyed (Munley, 1998).

Frictional ignition frequency in US coal mines is on the decline, but it still is a cause of concern because it has a potential to cause a mine explosion leading toa large-scale mine fire. Prevention of frictional ignition is based on the following:

The suggested steps will not only make mining safer but also more economic by enhancing coal productivity and creating a source of extra revenue from coalbed methane. Loss of production due to mandatory suspension of mining subsequent to an ignition will also be minimized.

Coal mines contain hazardous and explosive gases, and there is a potential for long-lasting fires. The OSM estimates that there are currently 4163 acres burning, including 94 sites where hazardous or explosive gas is being emitted from underground mine fires, which can have an effect on humans in the vicinity of the site. The estimated cost of extinguishing these fires is $860 million. The most extreme case in the United States is in Centralia, Pennsylvania, where an underground fire has been burning for longer than 30 years. Attempts to extinguish it have failed, leading the government to buy all the property at a cost of $42 million as well as costs associated with the attempts to fight the fire.

Many countries have developed tests and requirements for reducing the flammability hazards of materials used in mining operations. Countries with mining operations such as Australia, Canada, Germany, Great Britain, India, Japan, and the USA have written rules or requirements that address the flammability hazard of materials. The requirements are directed primarily toward specific materials such as conveyor belts, electric cable, brattice cloth and ventilation tubing, and hydraulic fluid that are used in underground coal mines. These specific materials were targeted for flame-resistant requirements because of mine fire incidents involving their use or perceived fire hazards. For example, the need for fire-resistant conveyor belts was brought to the forefront as a result of some disastrous fires. The Creswell Colliery coal mine fire in Derbyshire, England where 80 lives were lost (Creswell, 1952) and Schlagel-Eisen Colliery coal mine fire in Herten, Germany where seven lives were lost (Schlagel and Eisen, 1977) resulted in the development and implementation of stringent requirements for fire-resistant conveyor belts in both Great Britain and Germany. Subsequently, the former U.S. Bureau of Mines followed in the mid1950s with the development of a flame test method for evaluating the fire resistance of conveyor belts (Pollack, 1956), but a regulation mandating the use of fire-resistant conveyor belts in underground coal mines was not enacted until much later. The Coal Mine Health and Safety Act of 1969 mandated the use of fire-resistant conveyor belts in the underground coal mines in the USA (FCMS&H, 1969). Also, in Canada, a fire performance standard for conveyor belts used in underground mine operations was developed and adopted as a national Canadian standard (CSA, 1987).

Fire safety incidents and hazards with other materials such as electric cables, brattice cloth and ventilation tubing, and hydraulic fluids also resulted in test methods for determining flame resistance and regulations regarding their use in underground mining operations. Although the use of flame-resistant materials has grown, particularly with the introduction of plastics, in many cases regulations were needed to mandate their use. Other alternatives may be available such as fire detection and fire suppression systems, where the flammability of a material is of concern. However, flame-resistant materials provide a first line of defense for fire safety, but cost, performance, and issues on toxic gases produced during combustion are factors affecting their acceptance.

pulverizer fire and explosions

The presence of combustible materials in the pulverizer is usually the largest contributor to pulverizer fires. In most cases, pulverizer fires begin in the under bowl area of the pulverizer that is a very hot environment with an abundance of air. Accumulations of debris or coal anywhere in the pulverizer will increase the chance of a mill fire. The pyrite removal chute should be inspected often to ensure rejected material is removed from the under bowl area. Stoppage of pyrite chute flow can cause debris and-or coal to back-up into the primary air ducting.

Mill fires require immediate attention to prevent damage to the pulverizer and more damaging mill puffs. Explosions in a pulverized coal system are normally called puffs. A mill puff is an explosion in the mill system caused by an explosive combination of coal, air and temperature. Mill puffs most often originate in the under bowl area and can cause very destructive damage to the primary air ducting.

Mill puffs or explosions can be very dangerous resulting in serious damage to the pulverizer system or injury to personnel. When conditions that promote mill puffs are evident, personnel should promptly make correction actions and avoid the immediate area around the pulverizers.

Pulverizer airflow is adequate to facilitate stable transport of coal without settling in the burner line (>3,500 Fpm) but not excessively high to provide an abundant source of air for combustion in the presence of an ignition source. Ignition sources could be smoldering coal in the classifier, pulverizer or raw coal in the high temperature under bowl area.

All efforts must be taken to prevent coal from accumulating or settling in any of the pulverizer components. Dry coal that is allowed to remain in the pulverizer system can spontaneously ignite. Raw coal to the pulverizer must be uninterrupted and controllable. Precise feeder control and minimal stoppages above and below the feeder are crucial. Hot smoldering or burner raw fuel anywhere in the pulverizer system is considered serious. Raw coal that is allowed to spill into the under bowl (air inlet) section and is allowed to accumulate will be exposed to high temperature (usually 500F or higher) and will eventually smolder and begin to burn. It is imperative that raw coal spillage into the under bowl area be prevented. When raw coal spillage is observed, immediate action should be taken.

ICTs presentation Maximizing the Value from Catalyst Sampling and Testing fromReinhold NOx-Combustion-CCR/PCUG Conference in February 2019 isnow online. If you missed the conference, dont worry you can download it below. Request a copy of the presentation by simply filling out the form below:

ICTs presentation Maximizing the Value from Catalyst Sampling and Testing fromReinhold NOx-Combustion-CCR/PCUG Conference in February 2019 isnow online. If you missed the conference, dont worry you can download it below. Request a copy of the presentation by simply filling out the form below:

When it comes to replacing catalysts, power plant operators often find themselves following the manufacturers recommendations. Many manufacturers use a standardized model to predict when its time to replace catalyst layers. But if youre like most EGUs, you may wonder if this standard replacement schedule accounts for the unique operating conditions of your []

When it comes to replacing catalysts, power plant operators often find themselves following the manufacturers recommendations. Many manufacturers use a standardized model to predict when its time to replace catalyst layers. But if youre like most EGUs, you may wonder if this standard replacement schedule accounts for the unique operating conditions of your []

ICT to host open house: Guests can learn about new pilot-scale catalyst test facility Nov. 14th-15th, 2018. Open House Schedule Wednesday 11/14: 8 a.m. -5 p.m. Thursday 11/15: 8 a.m. 5p.m. For more information, contact: Elizabeth ~ [email protected]

ICT to host open house: Guests can learn about new pilot-scale catalyst test facility Nov. 14th-15th, 2018. Open House Schedule Wednesday 11/14: 8 a.m. -5 p.m. Thursday 11/15: 8 a.m. 5p.m. For more information, contact: Elizabeth ~ [email protected]

Innovative Combustion Technologies, Inc. (ICT) is proud to announce an agreement has been reached with Southern Research to manage and operate its bench-scale SCR catalyst testing facility, effective November 1, 2016. With this agreement, ICT adds the capability to provide catalyst activity testing to its existing SCR tuning and performance field testing capabilities. ICT will []

Innovative Combustion Technologies, Inc. (ICT) is proud to announce an agreement has been reached with Southern Research to manage and operate its bench-scale SCR catalyst testing facility, effective November 1, 2016. With this agreement, ICT adds the capability to provide catalyst activity testing to its existing SCR tuning and performance field testing capabilities. ICT will []

Innovative Combustion Technologies (ICT) is excited to announce that we are the new North Ameri- can sales agent for Loesche Energy Systems, Ltd. (LES) of the United Kingdom for dynamic classifiers, pulver- izers and technical services associated with size reduction of solid fuels for the power industry. Loesche GmbH was founded in 1906 in Berlin, []

Innovative Combustion Technologies (ICT) is excited to announce that we are the new North Ameri- can sales agent for Loesche Energy Systems, Ltd. (LES) of the United Kingdom for dynamic classifiers, pulver- izers and technical services associated with size reduction of solid fuels for the power industry. Loesche GmbH was founded in 1906 in Berlin, []

Mill Inerting and Pulverizer/Mill Explosion Mitigation Richard P. [email protected] (205) 453-0236 2013 Annual Meeting | WWW.PRBCOALS.COM Coal Mills are the Heart of a Coal Fired Plant Maximum capacity, reliability and performance of your operation rely on the critical roles that your coal mills perform: Conditioning coal for proper combustion. (Fineness, fuel distribution, throughput) Delivering 100% []

Mill Inerting and Pulverizer/Mill Explosion Mitigation Richard P. [email protected] (205) 453-0236 2013 Annual Meeting | WWW.PRBCOALS.COM Coal Mills are the Heart of a Coal Fired Plant Maximum capacity, reliability and performance of your operation rely on the critical roles that your coal mills perform: Conditioning coal for proper combustion. (Fineness, fuel distribution, throughput) Delivering 100% []

pictures: centralia mine fire, at 50, still burns with meaning

The Centralia blaze, still burning more than 50 years after it began, ranks as the worst mine fire in the United States. But it is by no means the only one. More than 200 underground and surface coal fires are burning in 14 states, according to the U.S. Department of Interior's Office of Surface Mining Reclamation and Enforcement.

And with worldwide demand for coal surging, especially in industrializing nations such as India and China, mine fires have emerged as a global environmental and public health threat. Thousands of coal fires rage on every continent but Antarctica, endangering nearby communities. The blazes spew toxic substances such as benzene, hydrogen sulfide, mercury, and arsenic, as well as greenhouse gases like methane and carbon dioxide. (See related story: "Seeking a Safer Future for Electricity's Coal Ash Waste.")

Many Centralia residents had long feared a calamity like the one that nearly unfolded that Valentine's Day. Four years earlier, Domboski's father had told a reporter, "I guess some kid will have to get killed by the gas or by falling in one of these steamy holes before anyone will call it an emergency."