Abstract
Contents
- Introduction
- 1. Theme urgency
- 2. The purpose and tasks master's work
- 3. Review of Research and Development
- 3.1 Overview of international sources
- 3.2 Overview of national sources
- 4. Technology of production of gas underground gasification
- Conclusion
- Source List
Introduction
The technology of underground coal gasification (UCG) - unconventional way of coal mining, which opens up new possibilities in working out coal seams with complex geological conditions of occurrence, combining production, refining and processing of coal. The essence of technology of underground ñoal gasification is in the drilling of wells from the surface to the coal seam with sboyka (compound) in the formation of one of the known methods, in the subsequent firing (creating managed hearth burning) coal seam and provide the conditions for the conversion of coal directly into the bowels of a combustible gas and the grant of the gas produced from wells on the earth's surface. Thus, all of the technological operations carried out gasification of a coal seam with the ground surface, without the use of an underground labor working, and the development of coal seam occurs in an environmentally acceptable manner.
Underground coal gasification is beneficial for those coal seams that meet the following criteria:
- layer should be on a depth of 30 to 800 m;
- capacity (thickness) of the reservoir should be greater than 5 m;
- ash content does not exceed 45%;
- layer should have minimal gaps;
- there can not be water to prevent contamination of drinking water.[2]
The main advantages of UCG technology include:
a) economic attractiveness - the cost of UCG gas significantly below the cost of production of natural gas;
b) the relatively high degree of environmental safety - especially in comparison with the traditional methods of coal production, leading to a situation ecological disaster in the coal mining regions;
c) ensuring the effect of "gas saving", reflected in the substitution of gas for UCG on TPS andboilers to use natural gas there. [3]
1. Theme urgency
The development of modern industry is accompanied by the ever-increasing consumption of fuel and energy resources, resulting in energy costs in the cost structure of the products range from 20 to 50%. The global trend of increasing prices of hydrocarbon fuels is pushing consumers to seek cheaper alternative energy sources. Ukraine's dependence on imported fuel requires detailed of the revised policy on the use of domestic energy resources, especially coal.
It is known that coal reserves in Ukraine is much richer than its own gas reserves. Strip according to various estimates Ukraine for another 50 years is enough, and coal Ukraine up to 400 years old stock. One of the ways to maintain the competitiveness of a number of production is gasification of solid fuels. scientists estimate deposits of coal suitable for gasification to 40.1 billion tons, or about 30% of the available reserves (117 billion tons). In their view, the Ukrainians are provided with raw materials for centuries. According to scientists, for 1 cu. meters of gas to be processed about 2 million tons of coal. At this time, for the underground gasification can be involved about 20 billion tons of balance sheet and off-balance sheet 3.8 billion tons of coal reserves. [5]
In the process of restructuring of the coal industry in Ukraine, a significant amount of non-working coal seams is out of balance and is not used. The resumption of production activities of mines that are in the process of closing, for completion of these layers by conventional methods is not cost effective. The most promising solution is underground coal gasification, which will make it possible to obtain a considerable ecological - economic effect. At present, day of Underground Coal Gasification is a competitive technology, the use of which produce gasoline, diesel and jet fuel, electricity, and many different chemicals. For underground coal gasification no external source of water, which is a major positive factor for the preservation of the environment, as opposed to water-intensive processes of mining, coal processing and the production of electricity from coal-fired power plants. Many processes require large amounts of thermal energy that can be easily produced by combustion synthesis - gas produced coal gasification. In addition, the synthesis - gas can be used in the gas piston of the electric plant, which is important for the long-term independent power production and civilian objects.
The reality of such project has been tested on a closed mine "Selidovugol." In general, for the period 1985 - 1991 years. here in the pilot were gasified about 3.5 tons of coal. Productive gas directed into the boiler - heat recovery system. [5] The main issue of unprofitable mines of Donbass can also be resolved through the use of the method of underground gasification. The average depth of which is up to 700 m, more than 15% of mines are deeper than 1000 m About 85% of coal found in seams 1.2m and only 15% have a greater thickness. For the production of synthesis - it is advisable to use gas coals B, D and DW. [5] [7]
Implementation of projects on transferring the restructured gas-producing mines in the discharge will give an opportunity to reduce budgetary costs of closing unproductive mines approximately 50 - 60% and to reduce the social burden for closing mines, creating an additional 40 - 50 jobs at one position.
2. The purpose and tasks master's work
The aim is to analyze the perspectives and methods of using the gas underground gasification to develop energy-efficient solutions to save energy resources. For the purpose of this disclosure is necessary to solve a number of problems:
1. Consideration of the process of underground coal gasification
2. An examination suitability for the Donbass coal gasification process
3. Determine a more appropriate method for the gasification of Donbass
4. Prospects for continued use of synthesis - gas
5. Assessment of changes in the ecological state of the environment
3.Review of Research and Development
Energy security is a prerequisite for the development of any economy. The process of underground coal gasification is considered and studied by over the years, as it is one of the most promising solutions for coal processing and preparation of combustible gas.
3.1 Overview of international sources
Today, almost all major coal-producing countries sharply increased interest in underground coal gasification. Intensive research work and practical held in China, in Australia, where in 2003 built a large enterprise that profile - with the use of these countries to apply earlier in the former Soviet technological scheme of gasification of coal seams. An active interest in this technology in countries such as India, Kazakhstan, Ukraine, USA, Vietnam, South Africa, North Korea, South Korea, and many others.
Work on the underground coal gasification in France conducted an "Study Group on coal gasification" (CEC), which consists of four private and public organizations. Experimental research project cost of 155 million francs was implemented in 1979 and was intended to 1995-2000 she was sent to gasify thin coal seams of less than 2 m at depths of 1000-2000 m (reserves of about 2 billion tons).
In the UK, the work of UCG led by the National Bureau of coal. Implemented the technical and economic assessment of possible applications of UCG. It is recognized to lead the development of cost-effective blowing steam-oxygen layers to high pressure at the depth of 500 to 1000 m in the preparation of the drilling channel. The maps coal fields suitable for development by the UCG, which are under the North Sea. The criteria of cost-effectiveness of their development. [22]
In Germany, the experiments were carried out with the UCG in 1975 Since 1982, all of the new coordinated research institution established by the mining companies Germany, "Research Society of new technologies of coal" (K2G). Developed an extensive program. The first part dealt with the studies of the properties of coal at great depths and conditions of its chemical transformation in situ. The second part deals with the definition of the properties and their prospects for coal gasification geological data. All these works were not related to the practical application of UCG. [19]
In the Netherlands, there was a long-term program of research at the UCG, consisting of three stages. The first includes laboratory work and ended in 1990, on its results, you can select the methods and scope of field studies. Research Center located at the University of Delft.
In the United States during the years 1972-1992. implement a program of learning the basics of underground coal gazafikatsii. There have been about 30 experiments in natural conditions in the coal deposits of the five states (Wyoming, West Virginia, Illinois, New Mexico, the Republic Sicko, Texas). [21]
3.2 Overview of national sources
In the field of underground coal gasification Ukraine has leading positions. At the time of the former Soviet Union worked several industrial enterprises in this profile. Some of these businesses operated successfully for several decades. Thus, in the Kuznetsk Basin for 40 years operated the South Abinskaya station "Podzemgaz" uninterruptedly supplying fuel gas to 14 small boilers and Kiselyovsk Prokopyevsk and closed in 1996 due to physical wear and tear.
In Dneprobasse (South Sinelnikovskoye field) gasify lignite seam capacity of 3.5 m at a depth of 60 m enclosing rocks are clays and sands of Paleogene relatively loose structure. In the soil, the coal seam had a thick (up to 30 m) with the value of the aquifer head up to 50 m and a permeability of 8 m / day. Power percarbonic aquifer was about 20 m from the filtration coefficient 6.4 m / day. Power sharing aquitard was at the top of the coal seam 10-16 m in the soil 1-3 m subcoal aquifer water level was performed.
In the Donbass underground gasification was carried out on Lisichansk station "Podzemgaz." There gasify inclined (38-60 °C) from coal seams 0.5-1 m at a depth of 60-250 m enclosing coal seam of the breed: the shales and sandstones of the Carboniferous period. Coal seam aquifer, and head up to 300-400 m above the horizon ignition. Typical of these sites was Small water abundance coalbed defined coalbed small capacity and permeability of 0.1 m / day. Roof and ground coal seams are impermeable rocks. Under these conditions, the pre-filmed head of groundwater in the coal seam and pumping was carried out vygazovannogo space. [15]
The development of underground coal gasification technology and the study of combustion processes under the ground engaged in: V.A. Matveev, N.A. Fedorov. Kreynin. Who offered to hold the underground gasification of coal in a horizontal channel in the preparation of the gas generator mining method. Significant contribution to the development of ideas and technology of underground gasification made P.V. Skafa.
In the book "Technology of underground reservoir of mineral deposits" V.I. Bondarenko, A.M. Kuz'menko , J.B. Gradushiy , O.V. Kolokolov, V.V. Kharchenko, N.M. Tabachenko, V.N. Pochepov General guidelines for forming a model of the underground development of stratified deposits. Learn the technological properties of minerals and the host rocks. Consider technological measures to reduce the environmental load in the mining region in underground mining. Prospects for the use of resources of Donbass coal deposits discussed in the book E.S. Gerasimov. The overall process of gasification and examined the historical development of G.A. Papafanasopulo. A new stage in development of underground coal gasification in Russia and around the world have studied S.N. Lazarenko , P.V. Kravtsov.
4. Technology of production underground gasification gas
The essence of the underground coal gasification technology is the initial drilling of two wells (vertical or sloping), then the elaboration of interconnected horizontal channel fired-called drift. Figure 3 shows the main elements: 1 - boreholes 2 - reaction channels 3 - flues.
Figure 1 - Basic elements of underground coal gasification
To create a horizontal channel used methods such as burning, hydraulic fracturing, deviated horizontal drilling, mine method, etc. After ignition of the coal combustion spreads on the surface of the roadway fire. Underground coal gasification is carried out by heat (1000-2000°C). The process is carried out under blast pressure - various oxidants (typically, air, O2 and steam-less CO2). For the supply of blasting and removal gas gasification is performed in wells in a particular order and forming a so-called underground generator. There are same chemical reactions that in conventional gas generators.
Compressed air from the compressor section is directed by air ducts to the gasifier, where it reacts at high temperature with carbon formed as a result of producer gas. Gas is supplied to the surface, where it is cooled, cleaned and fed to the consumer (TPS) due to the pressure developed at the blow machines injecting air into the gasifier. Burning coal seam surface is called the firing slaughter. Coal seam is burned slowly from the bottom up, and the fire face moves to the rise of the coal seam. As the burnt-seam degasification space is filled with rocks brings down the roof and bottom ash coal. Cross-section of roadway fire remains essentially the same, and the surface of the face of free access to the blast. Stream, washing the surface of the face of fire, gasifies coal in fuel gas. In the coal gasification process there are two steps: thermal decomposition step, in which the moisture released from the coal volatiles and steam and gas substances and the residue is coke, the gasification step, whereby the carbon coke by free or combined oxygen is converted in the flue gases and these gases react with oxygen and steam. [7] [9]
Thus, all of the technological operations carried out gasification of a coal seam from the surface without the use of an underground working labor, and development of coal seam occurs in an environmentally acceptable manner. Technology features allow the use of even the field, the development of which inefficient conventional methods.
Schematic diagram of the UCG is shown in Figure 4, where 1 - underground generator gas, 2 - compressed air, 3 - low-calorie gas, 4 - gas purification plant, 5 - air; 6 - compressor, 7 - combustion chamber, 8 - superheater 9 - flue gas with a temperature of 800-850 °C, 10 - gas turbine, 11 - exhaust pipe, 12 - economizer; 13 - alternator, 14 - power grid, 15 - steam turbine, 16 - condenser, 17 - pump, 18 - steam at 250 °C, 19 - water.
Figure 2 - Schematic diagram of the underground coal gasification
The estimated composition of the gas produced is characterized by the following ranges of change in the content of individual gas components:
a) using at the UCG technology blast air: C02 - 12,0-15,3%; SmNn - 0.1-0.7% O2 - 0.2%, CO - 10,0-14,0% H2 - 12,1-16,2% , CH4 - 2,0-4,0%; N2 - 55,0-60,0%; H2S - 0,01-0,06%. The calorific value of the lean gas - about 4 MJ/m3.
b) using a steam-oxygen blowing (after gas cleaning CO2): CO - 35.0% H2 - 50.0% CH4 - 7,5%; CmHn - 1,2%; O2 - 0,3%; N2 - 5,0%.
The calorific value of the gas produced at the same time - 10-13 MJ/m3. [14]1. Using the basic components (CO + H2) as the raw material for a wide variety of chemical synthesis processes which have already been developed commercially. Here, before all, we should highlight the production of methanol and dimethyl ether as a particularly promising alternative to petroleum diesel.
2. The second area concerns the evolution of hydrogen (the content in the product gas is 20-25%). This is - a versatile product whose consumption is drastically increase in the near future. Its scope is extensive, from fuel to hydrogen energy to a growing medium for bacteria in production of synthetic animal feed and biodegradable polymers to replace traditional polyethylene and polypropylene. Very it is important to note that currently the commercial implementation of all these technologies is constrained only by the high cost of hydrogen.
3. The use of gas as a reducing agent in metallurgical processes of direct reduction of iron and other metals. It should be noted that the focus on production gas chemical use requires a change in the process parameters in comparison with alternative energy production of gas. The economic attractiveness coal gasification projects, the highest, especially for low-quality raw materials with little to no cost. The introduction of gasification technology in manufacturing process enables the company to extract the maximum amount of energy from the raw materials, as well as to reduce disposal costs and reduce the impact the environment. [10] [17]