Manufacturer of cleaning equipment for coal handling & processing applications. Various features include double-wire braid hose, interchangeable blades, quick-connect hydraulic fittings, double-roller chain drives & hydraulic power heads & motors. Meets DOT & OSHA/MSHA standards.
Manufacturer of oil free screw compressors equipped for compression of process gases using the principles of positive displacement. Available in various sizes, single and multi-stage and designed to convey the process gases with complete freedom from any contamination by the lubricating oil. Features include the ability to adjust to variable flow rates, continuous operation with liquid injection to cool and clean the gas during compression without contamination by lube oil, high speed, high efficiency, compact size, no valves, less liquid used, no pulsation, no alternating forces and can handle impurities in gas streams. Applications include flare gas compression, waste gas compression, coke oven gas compression, landfill gas compression, refineries, pneumatic transport, vacuum generation, gas-air mixing plants, medicinal production, chemistry, petro chemistry and more.
ISO 9001 certified manufacturer of coal processing equipment. Products include pintle chain attachments, pintle chains, sprockets, steel hubs, and traction wheels for coal preparation and processing systems. Equipment made of stainless and alloy steel. Meets ANSI standards.
Designer, custom manufacturer & builder of special bulk conveyor systems for mining, power generation pulp & paper, resource recovery & other industries. Utilize conveyors such as belt, drag, fight, en masse, apron, hinged belt, vertical & flexible side wall, chain-belt bucket elevators of all types, screw conveyors, belt feeders, trippers, stackers, reclaimers & metering bins.
Manufacturer of cleaner coal equipment for mining industry. Products such as screens, centrifuges, cyclones, and ware protection parts are available. Material handled includes clean coal. Applications include classifying, dewatering, draining, de-sliming, refuse separating, and thickening.
Manufacturer of coal processing equipment including load controllers, metal detectors, & conveyor scales. Load controller applications include truck & rail loading, as well as bulk material processes. 4 line by 20 character alphanumeric displays for direct reading of truck I.D., load size, tons loaded, & ready-conveyor-feeder conditions. Capable of storing up to 15 truck I.D. numbers with 15 different load sizes as well as controlling multiple feeder gates. Optional accessories include remote control stations & vandal-proof enclosures.
Manufacturer of fully integrated coal processing equipment including truck hoppers, flex wall conveyors, aggregate storage bins, shuttle conveyors, weigh & volumetric batching equipment, color blending & batching systems, rapid pan mixers, mixer wash out systems, silos & dust control systems. Equipment can be custom designed to specifications.
Manufacturer of standard & custom coal handling equipment including centrifugal slurry pumps. Types of pumps include severe duty metal slurry pumps & heavy duty metal slurry pumps. Heavy duty metal horizontal end suction centrifugal slurry pumps range in sizes from 2 in. to 12 in. Severe duty metal vertical slurry pumps range in capacities from 100 gpm to 60,000 gpm & heads up to 300 ft.
Manufacturers Complete Line Of Portable & Stationary Belt Conveyors Including Lattice Frame, Channel Frame, Radial Stackers & Folding; Also Coal Crushers, Screening Plants, Blending Plants, Railroad Car & Truck Unloaders & Split Pulleys
Custom manufacturer of ceramic based abrasion resistant materials & products. Ceramic based materials & products include alumina ceramics, ceramic composites, silicon carbide, chutes & cones, pipe connections, elbows, ceramic lined fan blades & pipe fittings, FGD systems, expansion joints, abrasion resistant liners & linings, wall mounts, ceramic lined steel pipes, decorative floor tile, shut-off valves & wear parts. Capabilities include fabrication up to 40 ft. L x 8 ft. W x 8 ft. H dimension & 10 tons lift, lined & unlined pipe work up to 30 m diameter & manufacturing up to 1,010 mm semi-automatic segment bends. Abrasion resistant ceramic lined products are suitable for coal fired power plants, coal preparation plants, cement & steel, pulp & paper industry application.
Manufacturer of coal processing equipment. Available with variable-speed impact breakers, two set of impact grids, secondary screens, flexible chain mounted rotor/flail assemblies and scalping grizzly. Suitable for separation of rock out of the raw feed and foreign material such as wood, plastic and steel.
Manufacturer of coal processing equipment. Equipment features gasification conversion of coal and has been piloted, demonstrated, and commercially operated on a wide range of feedstocks including bituminous coal, sub-bituminous coal, lignite, biomass, coal char and wastes, and metallurgical coke.
Manufacturer of coal handling equipment for conveying, cleaning and analytic applications. Products include magnetic pulleys, suspended electromagnets, suspended permanent magnets, metal detectors, bin vibrators, heavy duty feeders, vibratory controls, and flotation technology.
Manufacturer of standard and custom chemical, coal, lime and polymer processing equipment. Municipal, pulp and paper and minerals industries served. Turnkey systems integration and designing services available. Made in USA.
Manufacturer of coal processing equipment. Products include in-line food, blast hole, dry stream, crossbelt, slurry & elemental analyzers, sampling & analysis stations, coal blend optimization systems, coal quality managers, gravity feed & pressure pipe samplers, process audit & calibration tools, particle size monitors & slurry sampling stations.
Manufacturer of industrial coal processing equipment. Products include duct, tubeaxial, general purpose, radial tip, and vaneaxial fans and compact pressure blowers. Available in 250,000 cfm flow capacity and 1,300 degrees F maximum operating temperature with various types, sizes, features, arrangements, and accessories. Material construction include carbon steel, stainless steel, and aluminum. Suitable for use in ventilation, dust control, pollution control, and forced draft applications. Also offers custom fans. Provide repair, maintenance, testing, weld documentation, stress analysis, and product evaluation.
Custom manufacturer of coal processing equipment including coal valves. Features of coal processing equipment include gate rollers, rack & pinion drive assembly & three phase motors, weatherproof enclosures & limit switches.
Manufacturer of standard & custom coal handling & coal processing equipment including electro magnets. Features include power supplies for cycling required for automated equipment, power supplies with various control options. Available in round, square & rectangular shapes.
Custom manufacturer of a variety of replacement parts for the power industry including the boiler, pulverizer, hammer mill, or coal yard. Alloys ranging from heat, wear, and corrosion resistant steel to ultra wear resistant white iron.
Manufacturer of coal processing equipment including air pollution control systems such as RF dust control filter, AC fabric filter, washdown, pneumatic conveying, dry fogging, rotary car dumper, fire protection & PLC control systems.
Manufacturer Of A Variety Of Products For The Mining, Coal Processing, Brick & Tile, Sand & Gravel, Scrap Recycling & Wastewater Management Industries. Products Include Hydrocyclones, Sieve Bends, Concentrating Tables, Vibrating Screens, Distributors, Custom Ceramic Lined Piping & Flotation Columns. Manufacturing Facility Includes Extensive Engineering, Lab & Testing Facilities Making Recovery Rates Available On Equipment. Capabilities Include Steel Fabrication, Welding, Machinery, Painting & Carpentry
Manufacturer Of Industrial Vacuum Filtration Equipment, Including All Types Of Disc, Drum, Horizontal Belt, & Belt Press Filters For All Industrial Applications. Complete Systems, New & Used. Supplies A Full Line Of Replacement Parts, Media, & Accessories For All Brands Of Filtration Equipment. Consultation Services For Filtering Process, As Well As Custom Design. Refurbish & Upgrade Existing Filtration Equipment. Rental Filtration Equipment Available
Lean manufacturing capable & ISO 9001:2000 certified worldwide manufacturer of standard & custom material handling equipment including coal processing equipment. Equipment include chain conveyors, heavy-duty roller conveyors, industrial conveyors, towline conveyors & enclosed track conveyors. Equipment are available in different sizes & specifications.
Distributor of coal processing equipment, specifically pumps. Types include vertical sump and process, chemical process, non-clog process, close-coupled process, high temperature magnetic drive, one-stage and multi-stage axially split, medium-duty and rubber-lined abrasive slurry, and vertical submersible pumps. Available in various models, specifications, and features. Other products include rotary, air-operated diaphragm, gear, and peristaltic pumps. Also offers custom pumping systems. Equipment reliability and asset management, on-site and 24/7 emergency field repair, rental, refurbishing, rebuilding, and redesigning services are available. Serves the mining and minerals industry.
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The necessity of coal preparation Various mineral impurities are mixed in the raw coal mining process. The quality of raw coal is affected by technical equipment and geological conditions. The quality of raw coal is less and less, the meteorite mixed with raw coal is increased, the ash is increased, the content of coal and pulverized coal is increased, and moisture is increased. The coal washer removes impurities from the raw coal, reduces ash and sulfur, improves coal quality, and meets the needs of users. After the coal is washed, the meteorite can be disposed of on site, which can reduce the inefficient transportation and create conditions for the comprehensive utilization of coal gangue. Coal washing is an indispensable process for deep processing of coal. Coal preparation plant also named coal wash plant. The coal directly mined from the mine is called raw coal. The raw coal is mixed with many impurities during the mining process, and the quality of the coal is different. The coal with small internal ash and large internal ash is mixed. together. Coal washing is an industrial process in which impurities in raw coal are removed or high-quality coal and inferior coal are classified. Coal preparation process Coal wash processing, meteorite processing, material and equipment transportation constitute the mine ground system. The ground coal processing system consists of coal, sieving, crushing, coal preparation, storage and loading. It is the main body of mine ground production. Screening The operation of dividing the mixture of different particle sizes into various granules by using a perforated screen surface is called sieving. The machine used for drying is called a sieving machine or a vibrating screen. In coal preparation plants, screening operations are widely used in raw coal preparation and processing. According to different screening methods, it is divided into dry screening and wet screening. BrokenThe crushing operations in the coal preparation plant mainly have the following requirements:1) Adapt to the requirements of the selected particles; the coal particles that can be processed by the selected machinery have a certain range, and the large pieces exceeding this range must be crushed before being washed; 2) Some coals are quickly caught by coal and vermiculite. Yancoal, in order to select clean coal from it, needs to be broken into smaller particles to separate coal from tantalum coal; 3) to meet the users particle requirements and to quickly crush the selected product or coal to certain particle size. The material is crushed mainly by mechanical methods, and there are several main methods such as crushing, chopping, breaking, crushing and grinding. Coal preparation Using different physical and physical-chemical properties from other materials, mechanically remove impurities in the raw coal in the coal preparation plant and divide it into products of different quality and specifications to meet the needs of different households. The modern coal washing plant is a continuous machining process consisting of many operations. Storage Coal storage bin: In order to regulate the imbalance between production, transportation, and sales, and ensure the normal and balanced production of the mine and transportation departments, a coal bin with a certain capacity is set up, and the finished coal is accepted to ensure smooth delivery and finalization. Loading stage. The invest of a coal wash plant Generally speaking, medium-sized coal washing plants have a capacity of 450,000 tons to 900,000 tons. The production system (note that the production system) is about 20 yuan/ton of investment in private enterprises. The profit difference is also large, and there are factors such as process flow, coal quality, management, market, etc., but if the scale can be completed, the profit will be profitable. Profit from tons of coal from 50-200 yuan. Taking a coal washing plant in Indonesia as an example, the coking coal preparation plant with an annual processing capacity of 4 million tons can increase the processing capacity per hour to more than 700 tons, and the power consumption, media consumption, fuel consumption, and water consumption are all reduced. At present, the whole plant consumes 1.42 kg. / ton, flotation fuel consumption 0.67 kg / ton dry slime, water consumption 0.09 cubic meters / ton, electricity consumption 9.32 degrees / ton. In 2017, it imported 1.682 million tons of raw coal, produced 977,000 tons of clean coal products, recovered 59.35% of clean coal and created a profit of 160 million yuan. Equipment needed for coal wash processing The equipment and process of the coal washing plant are related. The three most basic processes of the coal wash plant are the preparation work before the sorting (crushing, screening, grading), the sorting operation, and the processing of the selected products. At the same time, heavy medium coal preparation includes five major processes: coal flow, medium flow, circulating water system, slime water, and clean water. For example The annual selection of 1 million tons of raw coal, the technical process is 50 ~ 0mm raw coal de-sludge, using three-product heavy medium cyclone sorting, coarse coal slurry by TBS sorting, fine coal slurry flotation, tail coal Combined washing process of concentrated pressure filtration. Its main equipment is: pressureless three-product heavy medium cyclone, flotation machine, fine coal de-screening, magnetic separator, pressure filter, quick-open diaphragm press, thickener and so on. slime coal dewatering screen Specific equipment list The re-election equipment includes: heavy medium sorting machine, heavy medium cyclone Flotation equipment includes: flotation machine, flotation column, flotation bed, the slurry preprocessor Dewatering equipment: centrifuge,filter press, slime dewatering screen Others: magnetic separator, air dryer, air compressor, pump, curved screen, belt, scraper, grading cyclone, TBS, interference bed, Spiral Classifier Since its establishment, LZZG has designed and produced a large number of high-quality coal washing equipment for many coal washing plants by using a full set of mechanical equipment such as forging, turning, milling, planning and welding. It has been trusted by users and contributed to the promotion of social and economic development. Through years of production practice, we have accumulated rich production experience, complete production technology, perfect testing equipment, strong technical force and a complete set of scientific management system, so that the companys scale continues to grow.
Various mineral impurities are mixed in the raw coal mining process. The quality of raw coal is affected by technical equipment and geological conditions. The quality of raw coal is less and less, the meteorite mixed with raw coal is increased, the ash is increased, the content of coal and pulverized coal is increased, and moisture is increased. The coal washer removes impurities from the raw coal, reduces ash and sulfur, improves coal quality, and meets the needs of users. After the coal is washed, the meteorite can be disposed of on site, which can reduce the inefficient transportation and create conditions for the comprehensive utilization of coal gangue.
Coal washing is an indispensable process for deep processing of coal. Coal preparation plant also named coal wash plant. The coal directly mined from the mine is called raw coal. The raw coal is mixed with many impurities during the mining process, and the quality of the coal is different. The coal with small internal ash and large internal ash is mixed. together. Coal washing is an industrial process in which impurities in raw coal are removed or high-quality coal and inferior coal are classified.
Coal wash processing, meteorite processing, material and equipment transportation constitute the mine ground system. The ground coal processing system consists of coal, sieving, crushing, coal preparation, storage and loading. It is the main body of mine ground production.
The operation of dividing the mixture of different particle sizes into various granules by using a perforated screen surface is called sieving. The machine used for drying is called a sieving machine or a vibrating screen. In coal preparation plants, screening operations are widely used in raw coal preparation and processing. According to different screening methods, it is divided into dry screening and wet screening.
BrokenThe crushing operations in the coal preparation plant mainly have the following requirements:1) Adapt to the requirements of the selected particles; the coal particles that can be processed by the selected machinery have a certain range, and the large pieces exceeding this range must be crushed before being washed; 2) Some coals are quickly caught by coal and vermiculite. Yancoal, in order to select clean coal from it, needs to be broken into smaller particles to separate coal from tantalum coal; 3) to meet the users particle requirements and to quickly crush the selected product or coal to certain particle size. The material is crushed mainly by mechanical methods, and there are several main methods such as crushing, chopping, breaking, crushing and grinding.
Using different physical and physical-chemical properties from other materials, mechanically remove impurities in the raw coal in the coal preparation plant and divide it into products of different quality and specifications to meet the needs of different households. The modern coal washing plant is a continuous machining process consisting of many operations.
Coal storage bin: In order to regulate the imbalance between production, transportation, and sales, and ensure the normal and balanced production of the mine and transportation departments, a coal bin with a certain capacity is set up, and the finished coal is accepted to ensure smooth delivery and finalization. Loading stage.
Generally speaking, medium-sized coal washing plants have a capacity of 450,000 tons to 900,000 tons. The production system (note that the production system) is about 20 yuan/ton of investment in private enterprises. The profit difference is also large, and there are factors such as process flow, coal quality, management, market, etc., but if the scale can be completed, the profit will be profitable. Profit from tons of coal from 50-200 yuan.
Taking a coal washing plant in Indonesia as an example, the coking coal preparation plant with an annual processing capacity of 4 million tons can increase the processing capacity per hour to more than 700 tons, and the power consumption, media consumption, fuel consumption, and water consumption are all reduced. At present, the whole plant consumes 1.42 kg. / ton, flotation fuel consumption 0.67 kg / ton dry slime, water consumption 0.09 cubic meters / ton, electricity consumption 9.32 degrees / ton. In 2017, it imported 1.682 million tons of raw coal, produced 977,000 tons of clean coal products, recovered 59.35% of clean coal and created a profit of 160 million yuan.
The equipment and process of the coal washing plant are related. The three most basic processes of the coal wash plant are the preparation work before the sorting (crushing, screening, grading), the sorting operation, and the processing of the selected products. At the same time, heavy medium coal preparation includes five major processes: coal flow, medium flow, circulating water system, slime water, and clean water. For example The annual selection of 1 million tons of raw coal, the technical process is 50 ~ 0mm raw coal de-sludge, using three-product heavy medium cyclone sorting, coarse coal slurry by TBS sorting, fine coal slurry flotation, tail coal Combined washing process of concentrated pressure filtration. Its main equipment is: pressureless three-product heavy medium cyclone, flotation machine, fine coal de-screening, magnetic separator, pressure filter, quick-open diaphragm press, thickener and so on.
Since its establishment, LZZG has designed and produced a large number of high-quality coal washing equipment for many coal washing plants by using a full set of mechanical equipment such as forging, turning, milling, planning and welding. It has been trusted by users and contributed to the promotion of social and economic development. Through years of production practice, we have accumulated rich production experience, complete production technology, perfect testing equipment, strong technical force and a complete set of scientific management system, so that the companys scale continues to grow.
The coal washing plant added magnesium chloride to the slime water to increase the hardness of the water quality, and successfully solved the problem of the decrease in the hardness of the washing water due to the change of coal quality, which caused the clarified water area of the thickener to show a fine mud cover, the pressure filter discharge
The coal preparation plant generally adopts "cyclone, thickener, filter press (slime sedimentation tank)" processing technology. Under normal circumstances, it is purchased machine polymer flocculant (polyacrylamide). The high-molecular flocculant interacts with slime particles or slime colloids to neutralize the electrical properties of the slime surface, reduce the surface energy, and make the slime particles coagulate and settle. Different molecular weight flocculants
With the continuous deepening of urban construction and transformation, a large amount of construction waste has also been produced. The total amount of construction waste produced in Shaoxing, China last year reached 9.5 million cubic meters. Only the four road construction currently implemented in the urban area will generate 6 million tons of construction waste during the road demolition process.
The landfill is still a common sludge treatment method worldwide. Most landfill sites are mixed landfills. Due to (i) stricter and stricter environmental management, (ii) large amounts of greenhouse gas emissions from the organic degradation process, (iii) secondary pollution caused by leachate liquid, (iv) scarce land resources occupied by landfills, etc. Landfill laws are being gradually abolished in many countries.
On the morning of September 14, a batch of mining single hydraulic props and articulated roof beam equipment were loaded in the intelligent equipment manufacturing workshop of China Coal Group, and then they will be exported to Spain and the Middle East. Over the years, with high-quality products and perfect after-sales service, our group has sold more than 10,000 kinds of products to 34 provinces, cities and autonomous regions across the country, and exported to 158 countries and regions around the world, establishing a good reputation and reputation in the industry.
The single hydraulic props for mines exported to Spain this time were independently developed and produced by China Coal Group Intelligent Machinery Factory. The products have been innovatively improved to overcome the defects and problems of the DZ (piston) single hydraulic props and have large working resistance. , Light weight, long service life, large working stroke, low cost of use, convenient operation, wide range of use and good stability, and many other advantages. Since the product was put on the market, it has been well received by customers at home and abroad. At present, the 57 models of "ZHONGMEI" mining hydraulic prop products independently developed and produced by our group have all obtained the mining product safety mark certificate, and the products are very guaranteed in terms of quality and safety.
The products exported to the Middle East this time include single hydraulic props and hinged roof beams for mining. The hinged roof beam is a kind of mine support equipment, which is combined with various types of single metal pillars to form a metal support. It is a high-strength roof beam for the support of the coal mine in the horizontal and gently inclined working faces. It can realize cantilever support. There is a larger unsupported space between the coal wall and the pillar, which provides conditions for the realization of coal mining mechanization. The hinged roof beams produced by our group are of reliable quality, superior performance, complete technical parameters, and perfect after-sales service. The products are currently exported to many countries around the world and have won unanimous praise from customers at home and abroad.
As a member company of the United Nations Global Compact, China Coal Group has adhered to its global development strategy for many years and established China Coal Manufacturing Group Co., Ltd. in the Cayman Islands, UK. Established China Coal Group (China Coal Group) in the United States, Beijing Yike (Hong Kong) Network Technology Co., Ltd., China Mining Construction Equipment (Hong Kong) International Trade Co., Ltd., Shandong China Coal Mining Group (Hong Kong) International trade co., LTD, Established China Coal (Hainan) Import and Export Trading Co., Ltd. in Hainan. Continuously improve the global reputation and competitiveness of China Coal, and establish an international trading system of China Coal Group with the import and export of machinery and equipment as its core and resources and market as its elements.
At present, China Coal Group has a cross-border e-commerce team of more than 100 people covering English, French, German, Portuguese, Russian, Arabic and other languages. The group has registered the "China Coal" trademark in 38 countries and regions around the world. It has obtained the rights to use China Coal's trademarks in the 27 member states of the European Union and the United Kingdom, Mongolia, the Philippines, Indonesia, and Israel, and sold more than 10,000 coal mining machinery products to the world through the group's self-operated cross-border e-commerce platform Yikuang.com The group's global customers reached 480,000 in four countries and regions, making positive contributions to the development of international import and export trade!
In the future, China Coal Group will actively seize the opportunities of the times, increase overseas market expansion, expand the scale of foreign trade exports, and strive to enhance the international competitiveness of China Coal's own brands and the group's internationalization level. Promote the group's foreign trade import and export to a new level, and contribute more to the development of global trade!
Han Gao, Yili Duo, Tie Sun, Xuefeng Yang, "Dynamic Safety Management on the Key Equipment of Coal Gasification Based on Dbt-Dbn Method", Mathematical Problems in Engineering, vol. 2020, Article ID 7469470, 14 pages, 2020. https://doi.org/10.1155/2020/7469470
Gasifier system is one of the important components of coal gasification device. The technical characteristics of this system mainly lie in the following facts as huge technical scale and high complexity, and there is a dynamic correlation between the failure modes of gasification equipment. Traditional safety analysis methods such as fault tree and bow-tie diagram suffer from drawbacks as being static and ineffective in handling uncertainty, which hamper their application to risk analysis of process systems. This paper presents a newly developed model based on Dynamic Bow-Tie (DBT) and Dynamic Bayesian network (DBN) for quantitative dynamic risk assessment of gasifier system. In the meantime, in order to cope with the uncertainty of the failure data, fuzzy numbers and the defuzzification method are used to transform the experts' language into the failure rates. The results showed that dynamic risk assessment can solve the difficulties dealing with complex dynamic systems which have process variables and characteristics such as multiple, failure correlations, and noncoherence. And it also has important theoretical significance and application value for coal chemical industry to improve the scientificity of risk assessment.
Coal gasification plays an important role in human history, and this technology has been widely developed throughout the world, especially after the oil crisis in the 1970s . China is a typical rich coal, lean oil, and low gas country; coal energy accounts for more than 65% from the perspective of energy structure . Coal gasification is a new industry; China's shortage of oil and gas resources can be remedied by developing a safe, green, and environmentally coal gasification. With widespread and successful applications, this technology has greatly promoted the development of the coal chemical industry in China . The water-coal slurry gasification process is under simultaneous conditions of high temperature and high pressure; water-coal slurry and oxygen undergo a fierce redox reaction in the gasifier and generate syngas. The syngas is an inflammable and explosive mixed gas, so once an accident happens, it will not only lead to property loss, but also cause casualties and even environmental pollution. Therefore, as the key equipment of water-coal slurry gasification, it is necessary to analyze and describe the risk factors of the gasifier in this paper.
There also have been some researches regarding security problem in coal gasification process . Reference  reported many accidents in gasification plants during the last 20 years in the world; the researchers suggest that more careful concentration is needed during the design of the coal gasifier and the preparation of the constructed gasifier operation. Reference  developed a comprehensive technique to control the major hazards of the GE coal gasification process. The technique consisted of process hazard identification based on critical events, barrier performance evaluation based on barrier diagrams, and quantification of risk influence factors based on Bayesian network. Reference  introduced an efficient methodology utilizing improved Signed Directed Graph for the HAZOP analysis, and an industrial case about the coal conveying in a complex process of coal gasifier is modeled and analyzed. Although these researches focused on the safety issues in coal gasification process, the risk assessment methods applied in these researches were not dynamic, it encountered many difficulties in dealing with the safety assessment of complex systems such as polymorphism, nonmonotonicity, failure correlation , dynamics , process variables, and other influencing factors .
Dynamic risk assessment approaches can significantly reduce both the potential for hazardous events and undesirable consequences . In turn, it increases the safety of the operation and reliability of the systems; it is an extension of the definition of risk taking into account the time-varying characteristics. With respect to the dynamic risk assessment approaches, many researchers have done much work on it. Reference  proposed a complete set of dynamic risk assessment to predict the frequencies of abnormal events utilizing accident precursor data, helping to achieve inherently safer operations. Based on these methods, the failure probabilities of safety systems and end-states were estimated using copulas and Bayesian analysis to ensure better predictions. The method was further developed by Kalantarnia et al. , where a model was established. The model has used Bayesian theory to revise the risk profile, denoted as the posterior risk function, based on real-time data from the system. As pointed out in , Bayesian networks (BNs) have become a popular tool for quantitative risk assessment. Reference  aimed at developing dynamic safety analysis methodology for the offloading process for FLNG platforms using BN analysis. The purpose of conducting this safety assessment is to advance better understanding of the floating liquefied natural gas (FLNG) concept during the construction phase . Zarei et al.  applied BN to model accident scenarios of natural gas stations for risk assessment. However, BN is time-independent, and it cannot reflect temporal evolution of system and give prevention measures effectively. To this end, dynamic Bayesian network (DBN)  has been introduced, and it is equipped with other techniques such as bow-tie model [25, 26]. This composite model has been applied to quantitative risk analysis of hydrogen generation unit leakage  and offshore drilling incidents . Nevertheless, a composite analysis model of coal-water slurry gasifier accidents is not available; few studies concern this issue.
The present paper attempts to integrate DBN and dynamic bow-tie model  for dynamic risk analysis of coal-water slurry gasifier failure. Meanwhile, fuzzy numbers and the defuzzification method are used to transform the experts language into the failure rates, solving the problem that it is difficult to obtain a large amount of historical statistical data. The rest of the paper is organized as follows: A brief description of theoretical basis for dynamic bow-tie model and dynamic Bayesian networks is presented in section 2. Conversion rules and processing of DBN model are specifically described in section 3. The proposed method is applied for dynamic risk analysis of gasifier heating in the case study of section 4. Finally, the conclusions of this study are presented in section 5.
The bow tie model is an accident causality analysis method that combines fault tree and event tree analysis methods into one; this method can not only comprehensively analyze the causes and consequences of an event, but also clearly and intuitively describe the timing of the accident and the logical relationship of each event. The bow tie model is characterized by a fault tree on its left-hand side and event tree on its right-hand side with a bottom event in its center.
Dynamic bow tie model adds sequential notion to traditional FT method, building a complex system failure model, as shown in Figure 1 As an extension of ordinary static bow-tie, the dynamic bow-tie analysis not only includes Boolean logic relation but also includes dynamic logic gates (e.g., PAND, SEQ, SPARE, and FDEP), and some events reliability changes over time.
A static Bayesian network (BN) as a probability-based knowledge representation method is appropriate for the modeling of causal processes with uncertainty; it models a system at a fixed time [30, 31]. A DBN extends the notion of a Bayesian network to model the stochastic evolution of a set of random variables over time. To quantify the timing of discrete changes in the data, the state distribution at each moment contains a Bayesian network called a time slice. Therefore, structure and parameters in DBN do not vary over time, which reflects only the time-varying process of sample data. Then DBN can be split into an initial network and a transition network, representing the initial network as a probability distribution at the initial moment, transition network is expressed as transition probability distribution of adjacent time slices, as shown in equation (1):
Figure 2 is a structural diagram of DBN; different colors are used to distinguish nodes and directed arcs of different time slices. DBNs conditional probability can be divided into intra-slice CPT and inter-slice CPT. If a DBN can expend T time slices, the joint probability distribution of these T time slices is
DBN can be constructed directly from an understanding of sequential systems, while considering the existence of a large number of static/dynamic fault trees. DBN is modeled based on the existing FT model. Because historical information can be used for reference, this method not only effectively avoids subjectivity but also improves reliability. Meanwhile, this method also implements the method of automatic network construction by utilizing the rules of static/dynamic fault tree conversion to DBN, reducing the difficulty of DBN modeling.
The DBN corresponding to the Or gate logic is consistent with Figure 3 the conditional probability distribution of and is the same as in equations (1)(4). The conditional probability distribution of the node TE is shown as follows:
Figure 4 shows the DBN corresponding to the not gate logical relationship. The conditional probability distribution of is the same as in equations (1) and (2). The conditional probability distribution of the node TE is shown as follows:
Priority And gate includes several input events, and output events occur when they happen in a specific order, as shown in Figure 5. If events A, B, and C all occur, and event A occurs before event B, and event B occurs before event C, the output event will occur. Conversely, if not all three input events occur, or event B occurs before event A or event C occurs before event B, the output event will not occur. It is important to point out that if the input events occur at the same time, it is considered that the output event also occurs.
According to sequential and logical relationship of the priority and gate, two binary state nodes FS1 and FS2 need to be added. Among them, FS1=1 means that A happened before B, FS2=1 means B happened before C, FS1=0 means A did not happen before B, FS2=0 means B did not happen before C. The relationship between the Priority And gate and the DBN is shown in Figure 5, the conditional probability distribution of each node is
The sequence-correlated gate includes several input events, which require the input events to occur in a specific order (from left to right). Unlike priority and gates, sequence-correlated gates force their input events to occur only in a specific order. According to the temporal logic relationship of sequence-correlated gates, analyze the function-correlated gates of the three basic events in Figure 6 to obtain the dynamic Bayesian network corresponding to them, and the conditional probability distribution of each node is
The spare gate includes a main part and several backup parts. After the main part fails, the first backup part starts to operate instead of the main part. After the first backup part fails, the second backup part starts, and so on. The output event does not occur until all parts have failed. According to the numerical of dormancy factor , the spare gate can be divided into three types: cold spare gate , warm spare gate , and hot spare gate . Warm gate is discussed in this paper, as shown in Figure 7; other types of spare gates can be studied as special cases.where is the failure density function of component S in the backup period.
Function-correlated gate includes a trigger event and several related basic events, related basic events are repeatable event. According to the relationship between the trigger event and related basic events, Figure 8 shows the function-correlated gate which contains a trigger event and two related basic events, and the corresponding dynamic Bayesian network is shown as follows:
When using DBN for evaluation, it is necessary to obtain the failure probability of the device, but in practical production, the integrity of data of each device cannot be guaranteed. In view of this, using fuzzy numbers and the defuzzification method to transform the experts language into the failure rates is a practical solution. The fuzzy set theory was first proposed by zadeh and is often used to calculate the probability of fuzzy events. It is an effective way to deal with uncertainty or lack of information. In recent years, the combination of fuzzy set theory and Bayesian network has also been widely used in risk analysis and evaluation .
Expert elicitation is essentially a scientific consensus methodology, often used for calculating the probabilities of vague events. This method is a solution for dealing with uncertainty and lack of sufficient data and provides useful information for assessing risks. Eight different conversion scales have been provided by . In the present study, we use Scale 7 [VH, H, RH, M, RL, L, VL] (Table 1) for estimating the severity of an event. The reason for selecting scale number 7 is that humans memory capacity is seven plus-minus two chunks, and the linguistic terms are in the form of trapezoidal fuzzy numbers .
Since experts are different in knowledge and views, in order to reach a consensus among them, it is required to integrate the assigned terms by experts to a single one. For the objectivity of the data, this paper categorizes experts weighting criteria according to their education level, professional position, and experience time, as shown in Table 2. And five expert decisions are considered, and then expert language is converted into data. Table 3 shows some information about experts. Integrate the weights and fuzzy numbers of experts by linear weighting method, and equations (15) and (16), respectively, give expert weights and linear weighted integration. where refers to the weighting factor of the i-th expert, n of all experts, ET score, EL score and PP score are shown in Table 2.where is an aggregate fuzzy number of basic events, is the fuzzy probability assigned by an expert, n of all experts, and m of all events.
To draw useful results for decision making, the fuzzy probability of the basic and conditional events must be mapped to crisp number through defuzzification, and this facilitates computational reasoning in DBN. A trapezoidal fuzzy function can be defined as in Figure 9, defuzzification of the trapezoidal fuzzy number based on the center of area method can be calculated as equation (17).
The last step is to convert fuzzy possibility (FP) of vague events into fuzzy probability (FPr). A function developed by (18) is used for converting FPs to FPr:where FPs is fuzzy possibility and FPR is fuzzy probability for each event.
Through the analysis of the coal water slurry gasification process, combined with the HAZOP analysis report and expert opinions, the risk factors that lead to the overheating of the gasifier are identified, and the dynamic butterfly model shown in Figure 10 is constructed. Table 3 shows five experts information, Table 4 describes the basic events in the model. The model shows the evolution process of risk factors to accidents and accidents to consequences through dynamic fault trees and event trees.
It can be seen from Figure 10 that high oxygen-coal ratio, poor atomization effect of the burner, and low coal slurry concentration are the three main factors that lead to gasifier overheating. The oxygen-coal ratio is a key index for regulating the operating temperature of gasification in the production process. The fluctuation of the oxygen-coal ratio is mainly due to the abnormal feeding, the interruption of the coal slurry supply, or the sudden increase of the oxygen feed, so that the oxygen-coal ratio is higher than the set value, and the temperature of the gasifier also increases immediately. The atomization effect of the burner is closely related to the performance of the burner. If the pressure difference of the burner is low, the atomization effect will be significantly reduced, and the central-oxygen ratio is the main factor affecting the pressure difference of the burner. As the time elapsed, the burner is sprayed because uneven wear of coal slurry is also a factor that causes the atomization effect to deteriorate. The low concentration of coal slurry is mainly due to the failure of the pulping section or excessive flushing water entering the coal slurry line, which leads to a reduction in gasification efficiency and an increase in oxygen consumption, then leads to overheating of the gasifier. According to this model, it can be seen that a safety barrier is adopted in the project to prevent the expansion of the overheating accident of the gasifier, but the four safety barriers will also fail, resulting in different accident consequences. In this paper, the information of experts on basic events and safety barrier failure evaluation is transformed into corresponding fuzzy numbers according to equations (15)(18).
The evaluation information of experts is converted into fuzzy numbers corresponding to basic events and safety barriers according to equations (15)(18) in this paper. Then convert fuzzy numbers into fuzzy possibility (FP) based on center of gravity, and fuzzy probability for each event is calculated be equation . In addition, due to the maintainability of the equipment, this paper also calculates the maintenance rate () of the equipment. The above calculation data are shown in Table 4.
Figure 11 shows the DBN modeling for gasifier overheating and the simulation is based on application software (GeNie) which is an intuitive and easy-to-use software supporting a variety of inference algorithms. The DBN modeling of gasifier overheating is firstly established on the conversion algorithm including graphical and numerical conversion . The graphical structure is obtained by the conversion of fault tree and event tree which are connected by the central node transformed from the central event. In fault tree, input and output of logic gate turn into parent node and child node linked by directed arcs. In event tree, all possible consequences integrate into one consequence node and all safety barriers turn into safety nodes. Both safety nodes and central node are linked with the consequence node. The node generally takes two states to indicate the occurrence and non-occurrence of the event. In this study, the nodes of the basic events, intermediate events, and central event are represented by Y and N, the safety nodes are represented by W and F, Y indicates that the event occurs, and W indicates that the safety barrier has successfully prevented escalation of the accident. Especially, the consequence node consists of five states which contains\ identified possible consequences C1C4, and the added C0 state is set to indicate that the gasifier is not overheating.
The dynamic evolution of events has not been described through the above procedure because directed arcs only connect nodes in the same time slice. In order to accomplish the expansion of BN on the time slice, assume that the probability of fault occurrence follows exponential distribution. Therefore, the nodes of basic events are selected as dynamic nodes, and considering that safety barriers S1 and S3 are controlled by electronic systems, safety nodes S1 and S3 are dynamic nodes too. As shown in Figure 3, the dynamic node has a directed arc from itself in addition to linking with other nodes; that is, the node under the previous time slice is the parent node of it under the present time slice. Moreover, dynamic logic gates are added in BT modeling to represent the dynamic dependencies between events, and the connection between nodes is based on the mapping rule of logical gate to DBN in the section 2.
Prior probability and CPT need to be determined for quantitative analysis in DBN. FPr calculated by expert evaluation serves as prior probability, the result is shown in Table 3. A nodes CPT can be calculated by the mapping rules of logic gates in section 3, which consists of conditional probabilities under all its parent nodes. The conditional probability is calculated by probability density function for nodes between different time slices, and relevant calculation parameters , are also listed in Table 3. For safety barriers, the failure of overheating alarm leads to the failure of manual cooling operation; conditional probability is expressed as and other safety barriers are independent of each other. Developing 52 time slices after prior probability and conditional probability are input into GeNie, every time slice represents 1week.
The probability of gasifier overheating can be predicted based on DBN forward reasoning, causality, and prior probability of events. Figure 12 shows the probability of an over-temperature accident in the gasifier operating 52 weeks (1 year) with and without maintenance. It can be seen from the Figure 12 that in the first four weeks of gasifier operation, the probability of overheating accidents is not greatly affected by maintainability. What is especially worth noticing is that the probability of overheating of the gasifier will increase monotonically with time, so if no maintenance measures are taken within 52 weeks, the probability of accidents will be as high as 0.983. However, maintenance can be used to reduce the probability of accidents during operation, which shows the importance of maintenance measures for safe operation of the device.
Through DBNs forward reasoning, the probability of overheating causing different consequences can also be predicted. As shown in Figure 13, the probability of occurrence of each consequence also increases with time, the probability of the consequences C1, C2, C3, and C4 under the action of four safety barriers in Week 52 are 5.14E-01, 1.10E-01, 2.05E-02, 2.71E-05. Therefore, under the protection of the safety barrier, there is still a 51.4% probability that it can work normally even if the gasifier is over-temperature, thereby effectively avoiding further expansion of the accident. C2 and C3 are much larger than C4, indicating that even if the cooling the temperature fails, the emergency shutdown can still effectively prevent the accident from worsening. This also illustrates the importance of maintaining the normal operation of the emergency parking system.
It can be seen from above that the probability of overheating accidents in gasifiers is very high. Although the danger level can be reduced through maintenance and safety barriers, there are hidden dangers of untimely maintenance or failure of safety barriers. Thus, it is necessary to identify the key events that affect gasifier overheating and locate its weak links. DBN's diagnostic reasoning is a process from the child node to the parent node, dedicated to identifying the weak links in the whole risk scenario. This paper sets the gasifier overheating to Yes, then the posterior probability of the basic event at any time segment can be obtained, Figure 14 shows the posterior probabilities of weeks 4 and 52 for all basic events. In previous studies, the production process has not been divided into time segments for safety evaluation.
Figure 14 compares the prior probability, the posterior probabilities of weeks 4 and 52, the results show that the basic events with higher posterior probability in week 4 are X27, X1, X31, X13, and X26, and the basic events with higher posterior probability in week 52 are X30, X1, X22, X34, and X6. The comparison results show that the main event leading to gasifier overheating is equipment failure when running for about one month, while after a year, operation error is the main factor leading to gasifier overheating. Comparison results show attention should be paid to equipment maintenance at the initial stage, while one year later, safety management needs more attention to avoid accidents caused by operational errors.
(1)Based on fuzzy mathematics and DBN, a quantitative dynamic risk analysis of gasifier overheating was carried out. For the problem of incomplete historical data of equipment in the actual production process, fuzzy logic concepts were employed, which convert the experts linguistic judgement to aggregated results in the aggregation process, and this method was feasible.(2)The DBN model of gasifier overheating was constructed, dynamic change law of equipment failure rate when system running for 1 year was obtained by forward reasoning method. According to DBT converted to DBN, the main event leading to gasifier overheating is equipment failure when running for about one month, while after a year, operation error is the main factor leading to gasifier overheating. At the same time, the maintenance factor was also considered, and the impact on the system failure risk analysis when repaired or not is compared.(3)Based on the reasoning function of DBN, fault diagnosis of gasifier overheating was carried out. The prior probability of root nodes was obtained by fuzzy set theory, and then posterior probability of root nodes were deduced and sorted by the powerful reverse inference function of DBN; thus, the weakness of the system were identified. The calculation results show that with the prolonging of time and the increase of precursor incident, equipment failure probability and accident risk show a significant growth trend.
The authors are grateful for National project funding for Key R & D programs under Grant no. 2018YFC0808500, Scientific Research Project of the Department of Education of Liaoning Province (No. L2019044), and the Natural Science Foundation of Liaoning Province (No. 2019-ZD-0056).
Copyright 2020 Han Gao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Coal is defined as having more than 50 percent by weight (or 70 percent by volume) carbonaceous matter produced by the compaction and hardening of altered plant remainsnamely, peat deposits. Different varieties of coal arise because of differences in the kinds of plant material (coal type), degree of coalification (coal rank), and range of impurities (coal grade). Although most coals occur in stratified sedimentary deposits, the deposits may later be subjected to elevated temperatures and pressures caused by igneous intrusions or deformation during orogenesis (i.e., processes of mountain building), resulting in the development of anthracite and even graphite. Although the concentration of carbon in Earths crust does not exceed 0.1 percent by weight, it is indispensable to life and constitutes humankinds main source of energy.
This article considers the geological origins, structure, and properties of coal, its usage throughout human history, and current world distribution. For a discussion of the coal-extraction process, see the article coal mining. For a more complete treatment of the processes involved in coal combustion, see the article coal utilization.
The discovery of the use of fire helped to distinguish humans from other animals. Early fuels were primarily wood (and charcoal derived from it), straw, and dried dung. References to the early uses of coal are meagre. Aristotle referred to bodies which have more of earth than of smoke and called them coal-like substances. (It should be noted that biblical references to coal are to charcoal rather than to the rock coal.) Coal was used commercially by the Chinese long before it was used in Europe. Although no authentic record is available, coal from the Fushun mine in northeastern China may have been employed to smelt copper as early as 1000 bce. Stones used as fuel were said to have been produced in China during the Han dynasty (206 bce220 ce).
Coal cinders found among Roman ruins in England suggest that the Romans were familiar with coal use before 400 ce. The first documented proof that coal was mined in Europe was provided by the monk Reinier of Lige, who wrote (about 1200) of black earth very similar to charcoal used by metalworkers. Many references to coal mining in England and Scotland and on the European continent began to appear in the writings of the 13th century. Coal was, however, used only on a limited scale until the early 18th century, when Abraham Darby of England and others developed methods of using in blast furnaces and forges coke made from coal. Successive metallurgical and engineering developmentsmost notably the invention of the coal-burning steam engine by James Wattengendered an almost insatiable demand for coal.
Up to the time of the American Revolution, most coal used in the American colonies came from England or Nova Scotia. Wartime shortages and the needs of the munitions manufacturers, however, spurred small American coal-mining operations such as those in Virginia on the James River near Richmond. By the early 1830s mining companies had emerged along the Ohio, Illinois, and Mississippi rivers and in the Appalachian region. As in European countries, the introduction of the steam locomotive gave the American coal industry a tremendous impetus. Continued expansion of industrial activity in the United States and in Europe further promoted the use of coal.
Coal is an abundant natural resource that can be used as a source of energy, as a chemical source from which numerous synthetic compounds (e.g., dyes, oils, waxes, pharmaceuticals, and pesticides) can be derived, and in the production of coke for metallurgical processes. Coal is a major source of energy in the production of electrical power using steam generation. In addition, gasification and liquefaction of coal produce gaseous and liquid fuels that can be easily transported (e.g., by pipeline) and conveniently stored in tanks. After the tremendous rise in coal use in the early 2000s, which was primarily driven by the growth of Chinas economy, coal use worldwide peaked in 2012. Since then coal use has experienced a steady decline, offset largely by increases in natural gas use.
In general, coal can be considered a hydrogen-deficient hydrocarbon with a hydrogen-to-carbon ratio near 0.8, as compared with a liquid hydrocarbons ratio near 2 (for propane, ethane, butane, and other forms of natural gas) and a gaseous hydrocarbons ratio near 4 (for gasoline). For this reason, any process used to convert coal to alternative fuels must add hydrogen (either directly or in the form of water).
Gasification refers to the conversion of coal to a mixture of gases, including carbon monoxide, hydrogen, methane, and other hydrocarbons, depending on the conditions involved. Gasification may be accomplished either in situ or in processing plants. In situ gasification is accomplished by controlled, incomplete burning of a coal bed underground while adding air and steam. The gases are withdrawn and may be burned to produce heat or generate electricity, or they may be used as synthesis gas in indirect liquefaction or the production of chemicals.
Coal liquefactionthat is, any process of turning coal into liquid products resembling crude oilmay be either direct or indirect (i.e., by using the gaseous products obtained by breaking down the chemical structure of coal). Four general methods are used for liquefaction: (1) pyrolysis and hydrocarbonization (coal is heated in the absence of air or in a stream of hydrogen), (2) solvent extraction (coal hydrocarbons are selectively dissolved and hydrogen is added to produce the desired liquids), (3) catalytic liquefaction (hydrogenation takes place in the presence of a catalystfor example, zinc chloride), and (4) indirect liquefaction (carbon monoxide and hydrogen are combined in the presence of a catalyst).
Different types of particle size reduction equipment are available and each has its own method of reduction. The right size reduction machine for the task is the one that can add energy most efficiently for the application.
From the beginning of time, humans have found it necessary to make little pieces out of big ones stone, ore, ice, grain and more. It was a slow, laborious process for many centuries. Then in the Stone Age came the first breakthrough we call it a hammer and it worked better than ever. It worked so well, in fact, that it's still one of the most widely used tools in the world.
Today, there are many different size reduction machines available to make little pieces out of big ones. Particle size reduction equipment includes primary impact crushers and secondary crushers as well as milling machines - cage mills, hammer mills, pulverizers and grinders.
Stedman manufactures a full line of particle size reduction equipment primary impactors, secondary crushers, tertiary impactors, plus cage mill pulverizers,hammer mill crushers and lump breakers for the aggregate, mining and industrial markets. Materials processed fall into broad categories including abrasive, non-abrasive, wet or dry, sticky and friable.Stedman's experience evaluating these factors helps target the correct size reduction equipment for each unique project.
As you look for particle size reduction equipment, if you have the answers to the following basic questions, a good, experienced supplier can help you maneuver through designing the best equipment for your application. Begin by answering these five questions:
The Stedman Testing and Toll Processing Facility is the place to test your material in our full size equipment. If it can be crushed, ground, pulverized or mixed, chances are weve done it. We have more than 10,000 test reports to help get you to the best solution quickly.To learn more about what to expect from testing, read our article that ran in POWDER BULK ENGINEERING magazine.
Why Stedman? Delivering equipment and service you deserve For nearly two centuries, Stedman Machine Company has produced quality, reliable and durable size reduction and industrial crushing equipment. Stedman has expert field service and installation technicians ready to assist with all maintenance and equipment commissioning needs. Unsurpassed industry experience operating since 1834 State-of-the-art equipment testing facilities Dedicated, professional staff Parts and service available 24 hours a day
For nearly two centuries, Stedman Machine Company has produced quality, reliable and durable size reduction and industrial crushing equipment. Stedman has expert field service and installation technicians ready to assist with all maintenance and equipment commissioning needs.
Impact size reduction incorporates striking to pulverize material. The primary types of impact crushers include horizontal shaft impactors (HSI), cage mill pulverizers, and vertical shaft impactors (VSI).
Coal mining has been performed since the arrival of the Industrial Revolution in the mid-18th century. Coal is used as a fuel primarily for steam-generated electrical power plants, as well as being a component of certain industrial applications, such as steel manufacturing. Coal is widely distributed over the planet, either as underground seams which must be mined, or as deposits located closer to the earth's surface. The latter can be extracted at the surface by removal of the topmost layer of earth and rock covering the coal seam.
More than two-thirds of coal extracted underground is done by a "continuous miner," a tractor with a mounted cylindrical grinder that breaks coal away from the seam. The continuous miner deliberately leaves undisturbed pillars of rock and coal in the mining area to create natural supports for the ceiling. This is known as "room and pillar" mining. When most of the coal seam has been extracted, the pillars then are mined one by one, allowing the roof to naturally cave in.
Twenty percent to 30 percent of mined coal underground is from longwall mining. This is performed by a mechanical cutter that shears coal off from a panel on the seam. The panel being worked on may be up to 800 feet in width and 7,000 feet in length. Mined coal is deposited onto a conveyor that moves the coal to a collection area. Hydraulically powered shields over the machine provide ceiling support. Longwall mining is more efficient than room and pillar mining, but the equipment is more expensive.
For extracting coal which lies close the surface, huge drag-line shovel machines remove the topmost layers of soil and rock, exposing the coal, which is then removed by smaller machines. Surface mining may involve removing sections of hills or top layers of a flat surface area. The layers of rock and dirt covering the coal are reserved for until the coal is removed, at which point the the dirt and rock is replaced, the mine covered over, and the environment restored as much as possible to its original condition.
Conventional mining employs crews of miners who use explosives and drills to extract coal, which is then loaded onto cars for transport to the surface. This method presents higher risks to miners because of the explosives. The coal dust generated by the drilling and explosives is also a health hazard when continuously inhaled. This is the oldest method of coal mining.
Based in Los Angeles, Peter De Conceicao has been a professional researcher and writer since 2000. He has also worked as a writer for nonprofit educational organizations. Most recently, his work has appeared in Examiner.com as a news analyst and social commentator. He holds a degree in communications from Loyola Marymount University.
Categories of met coal include hard coking coal, semi-hard coking-coal, semi-soft coking coal and pulverized coal for injection (PCI). These apply to the different quality grades of met coal, all of which are used to make steel.
BNSF plays a vital role in our economys supply chain, moving freight across our nation every day. Here we explore how our investments and innovations enable the reliable and efficient delivery of freight.
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Rotary Aluminum Gondola All specifications are approximate and may vary between car builders and car owner specifications. Specifications Table Diagram Coupled Length 53.1 ft Net Carrying Capacity 121 tons Gross Weight on Rail 143 tons Door Actuation N/A
Aluminum Bottom Discharge All specifications are approximate and may vary between car builders and car owner specifications. Specifications Table Diagram Coupled Length** 53.1 ft Net Carrying Capacity 117 tons Gross Weight on Rail 143 tons Door Actuation Remote Air Activated Release ** Required length for rotary gondolas but only required for bottom discharge equipment if equipped with rotary couplers.
Steel Manual Hopper All specifications are approximate and may vary between car builders and car owner specifications. Specifications Table Diagram Coupled Length** 53.1 ft Net Carrying Capacity* 102 tons Gross Weight on Rail* 131.5 tons Door Actuation Manual Door Release * Majority of steel equipment in coal service is restricted to 131.5 gross weight on rail. Some recently built equipment is capable of 143 tons. ** Required length for rotary gondolas but only required for bottom discharge equipment if equipped with rotary couplers.
Coal is a flammable black or brownish-black sedimentary rock, which is usually formed in lithostrata or veins known as coal beds or coal seams. Sedimentary rocks are exposed to rising temperature and pressure to form hard forms of coal that are considered metamorphic rocks, such as anthracite. Coal is believed to be formed by the transformation of ancient plant remains buried under the ground through: peat lignite bituminous coal anthracite, and anthracite can be further converted into graphite.
Organic matter in coal is a complex macromolecule organic compound, which is mainly composed of carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus, and the sum of carbon, hydrogen and oxygen accounts for more than 95% of organic matter.Inorganic matter in coal also contains a small amount of carbon, hydrogen, oxygen, sulfur and other elements.
Carbon is the most important component in coal, and its content increases with the deepening of coalification. The carbon content in peat is 50%-60%, lignite 60%-70%, bituminous coal 74%-92%, anthracite 90%-98%.
Sulfur is the most harmful chemical component in coal. During coal combustion, sulfur generates SO2, which pollutes the environment. So the United States has established regulations to control sulphide emissions because it is expensive to remove harmful impurities containing sulfur, so governments reward the production of low-sulfur coal to reduce pollution.
According to the different carbonization degree of coal, coal is divided into peat, lignite (brown lignite, black lignite), subbituminous coal, bituminous coal (raw coal) and anthracite. The carbonization degree of anthracite is the highest and that of peat is the lowest.
Coal is used for coking and can produce coal tar and ammonia. Coke is an important raw material for ironmaking. Coal tar can extract a variety of important industrial compounds. Coal is the main fuel for heating in winter.
As an important raw material for ironmaking, coke plays a key role in the iron quality. The coal used for coking must be washed and selected to reduce the ash and sulfur content. Coke has high calorific value and does not smoke, its a good fuel.
Coal gasification is a production process in which coal is used as raw material and a series of chemical reactions occur between organic substances and gasifier agent in coal under high temperature and pressure in a specific equipment (such as gasifier), so as to convert solid coal into combustible gas. After gasification, coal burns more fully and is more conducive to transportation and storage.
Coal liquefaction is a process of converting coal into clean liquid fuel (gasoline, diesel oil and kerosene, etc.) and chemical raw materials (carbon fiber, binder, etc.) under special conditions. The liquefaction of coal helps to reduce the demand for natural oil.
Coal is important raw material for the production of fertilizers, plastics, synthetic rubber, synthetic fibers, explosives, dyes, medicine and other important chemical raw materials, but also an important way to obtain aromatic hydrocarbons in industry.Get in Touch with Mechanic