TEHPLAZ Ltd. SIE Description the process of plasma stabilization of dust coal fuel burning in the boilers of thermal electric power stations and technical-economic estimation of it

	Index
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	1.ANALYSIS OF FUEL CONSTITUENT OF POWER COMPLEX. The technology of mining accepted for today jointly with containing breeds allows more effectively to use a mountain technique, to raise load on the mining face, and, consequently, and efficiency of the coal mining on the whole. Such technology of mining supposes his subsequent enriching in order to provide a necessity to the users quality of supplied with coal. However, in connection with lag of development of modern powers on enriching of coal, quality of commodity products constantly goes down and falls short of to projects descriptions. Therefore the coal thermal stations (рщя) work on no projects bad qualities fuels (high-ash ordinaries are coals, sifting out, by-products of enrichment-coal), that results in the considerable decline to power, damage and wear of equipment, worsening of ecological indexes. In addition, low reactionary ability of these fuels conditional necessity of incineration them with considerable additions of natural gas and fuel oil. It is known that at the use of fuel oil for ignition and stabilizing of burning of coal-dust torch arise a lot of specific problems of technical, economic, ecological and social character. For partial or complete their decision the search and application of the new technologies of use of fuel, based on modern achievements of science and technique, are needed. One from the most progressive directions of today''s energy is development and industrial mastering of plasma technologies of processing and incineration of fuel on the basis of high-quality new plasma-power vehicles and processes. To undoubted advantages of plasma technology it is necessary to deliver its high selectivity, possibility of processing of different types of raw material, small sizes of basic equipment, low of lag effect, high concentration of energy and ecological cleanness. 2. PHYSICAL BASES OF PLASMA STABILIZING OF BURNING OF COAL-DUST FUEL. In work [1] information is resulted on comparison of methods of incineration of coal in a gas burner, in a thermo-electric heater and in a plasma stream. Comparison of results shows that at admission of coal-dust aeromixture through arc-heating plasma termochemical transformation of coal takes place more intensively, I.e. plasma is instrumental in more rapid and complete decomposition of coal. Thus plasma operates not only as generator of heat but also as catalyst of termochemical transformations of coal due to the increase of internal energy of particles because of excitation of rotator, swaying and electronic levels. At the identical expenses of thermal energy it is set on incineration of coal, that during the plasma stabilizing of burning the output of volatile and combustible increases approximately in two times [1]. Accordingly underfire diminishes also in two times as compared to stabilizing of burning by a gas torch or electro-thermal heating of coal. As a result of the experimental data processing at identical one middle-mass the temperature with the ordinary thermal heating and treatment of coal it is set in plasma, that probability of reacting on the output of volatile components in plasma increases more than in 2 times, and probability of reacting on burning down of carbon increases more than in 2,7 time. Estimations show that the plasma stabilizing of coal-dust torch makes complex influence on the process of combustion of coal into heating space. Thus on the increase of efficiency of process of combustion of coal mechanisms have most influence increase of specific warmth of combustion of coal particle in a plasma stream and decline of middle-mass heat capacity of products of combustion. 2.1 INCREASE OF SPECIFIC WARMTH OF COMBUSTION OF COAL PARTICLES IN A PLASMA STREAM On the basis of the experimental findings and executed theoretical calculations for the reliable plasma stabilizing of coal-dust torch in a coal-dust sprayer with the expense of power coal ~10 Йg/s must be set by plasmotrone power to 200 kбt. Do calculations show that at the middle heat capacity of coal dust of яr~1000 J/[kg•й] increase of temperature of dust on the cut of gas-ring due to bringing of such amount of heat will make all 20┘25╟я. How ever much rapid and local admission of heat from oxidizing plasma results in violent oxidization of coal dust in oxygen of primary air. As a result of it there is formation of ян2 (burning) or CO (gasification) with the apportionment of considerable part of thermal energy (avtotermyya) and a temperature on an exit from a sprayer increases to 300-700 ╟я (mathematical modeling of mechanism of the plasma illuminating [enclosure3]) As is obvious from picture 1 at distance from plasmotrones to the exit from a coal sprayer equal 2 Л and speed of stream ~30 Л/Я, hit in the plasma stream of particles by a diameter to mkm 70 over to brings their gasification yet to the hit in heating space of caldron ( mathematical design of mechanism of the plasma illuminating from beneath [enclosure3] ). Picture 1 is Process of burning down of particle of coal with the warmth of combustion 20000 ЙдФ/ЙЦ in a gas stream at a temperature to 3000 й. On graphic of burning resulted: temperature of gas of рg; temperatures of particle of рp; diameter of particle d0. A calculation is conducted for the following variants : 1 √ initial diameter of particle d0=25 mkm; 2- d0=50 mkm; 3 √ d0=70 mkm. As is obvious from picture 2 a to 50% factious composition of dust make particles a size less than 70 mkm, consequently, a to 50% mass of coal can be installed gas by plasma yet in the trunk of gas-ring at creation of the proper terms. Picture 2 are Complete corn descriptions of dust of brown coal, got on two types of mill[5]. 1 - grinding in a hammer mill; 2 - grinding in a ball mill; 3 - region of thin factions; 4 √ also rough. So rapid burning down of coal particles (time of burning down cut 0,01-0,07) results in formation of chain reaction of process of burning, the limiting factor of which the amount of oxygen of contained in primary air and speed of his diffusion to the area of burning becomes only. Plenitude, and, consequently, and the warmth of combustion of particles of coal at the high temperature and intensive process of burning will be higher, than at the temperature of realized into a combustion chamber (max 1300╟я). It takes place on row of reasons: - it is influence of heat-prostration results in of particle, frequent increase of surface of burning and exception of not burning out of remaining carbon into the baked ash residue; - bursting of particles results in destruction of spongy structure of coke remain, the presence of which often results in absorption by the remain of volatile with their by the subsequent delete at ash disposal; - the increase of temperature of burning results in the increase of degree of combustion poorly reactionary organic compounds and resin, practically noncombustible at 1100-1200╟я, and also acceleration of other poorly flowing exothermic reactions; - also possible and other reasons related to the change of intermediate reactions and chemical composition of products of combustion of coal. On results the mathematical modeling ( Mathematical design of mechanism of the plasma illuminating from beneath [enclosure 3] ) of conducted it is certain on the basis of the experimental working off technology ( [enclosure 1] ), that the specific warmth of combustion of coal of installed gas under act of plasma is multiplied on 15-20% here, the amount of coal of exposed to plasma gasification is 7-10% from the total expense of dust through a sprayer. The increase of specific heating value allows to decrease the required expense of coal at saving of thermal power of heating. 2.2 DECLINE OF MIDDLE-MASS HEAT CAPACITY OF PRODUCTS OF COMBUSTION The mechanism of change of middle-mass heat capacity of products of combustion is other mechanism of increase of efficiency of plasma technology of stabilizing. The experimental results got by gas analyzer are confirmation of this mechanism, which show the decline on 18-20% concentrations of the harmful troop landings(Industrial tests report of the plasma setting of PUMAS-4 on stabilizing of burning of coal-dust fuel on the caldron of block ╧8 йurakhovskoy HES (heat-electro-station), from 1999Ц. [enclosure 1] ), and confirm the change of chemical composition of products of combustion. Mechanism of influence of the stabilizing system in given cases corresponds to the mechanism of incineration of coal in two stages, with preliminary running gasification of coal dust. And although time and power of plasmotrones not sufficiently for complete gasification of all coal-dust fuel, however gasification 10-15% from all fuel is carried out in the trunk of gas-ring [1]. Results of mathematical design, show the decline on 3-5% middle-mass warmly capacities of products of combustion, and, consequently, diminishing of losses with the outgoing products of combustion due to partial gasification of coal-dust stream by oxidizing plasma 2.3 RESULTING INFLUENCE OF PLASMA ILLUMINATING FROM BENEATH Developed mathematical model, the executed calculations and industrial tests, showed, confirm efficiency of the use of the system of the plasma stabilizing of burning of organic fuel. Except of expansion of range of work of standard caldron, both on powers and on acceptable quality of coal raw material, the plasma stabilizing results also in diminishing of the harmful troop landings, increase of degree of the use of oxygen, increase of temperature of area of the active burning (diminution of underfire), decline of losses with leaving gases and decline of consumable expense of coal dust almost on 20% (picture 3) ( Mathematical design of mechanism of the plasma illuminating from beneath [оПХКНФЕМХЕ3] ). Picture 3 - Dependence of change of temperature in semi heating of caldron and expense of coal from power of plasmotrones ∆[%]= (value of parameter with stabilizing / value of parameter without stabilizing)•100% 1,2 √temperature in semi heating at thermal power 160 and 110 Mбt accordingly; 3,4 √expense of coal at thermal power 160 and 110 Mбt accordingly. 3. THE RESULTS OF INDUSTRIAL OF DUCT COAL COMBUSTIBLE STABILIZATION TEST The conducted industrial tests (act of industrial test dated back to the 26th of August, 1998, supplement 1) of plasma energy technology of coal burning with the heat creating ability of approximately 4000 Kcal a kilogram with the output of volatile of about 35 percent on the 8-th block of Kurahovsky electric power station displayed that the power of plasmatron didn▓t exceed 0,3 percent of the power of the flammable duct-coal aeromixture. It was determined that for a stable operation of one half-furnace in the diapason of the load change of a bloc from 120 to 6200 MW would be enough for one or two plasmatrons whose power was up to 400 KW and that for the whole block two or four plasmatpons whose power was up to 700 KW would be enough (see supplement 2). It was determined during working plasma technology out on block 8 at Kurahovsky electric power station that the energy of a plasma jet was used the most effectively while putting it directly into dust-coal flow which was in the barrel of the burner. With all that either furnace black appearance on the wall of the burner. The research of heating areas in the barrel of the burner with plasma accompanying burning displayed that the temperature in flow near the wall could reach 1200 0C. Therefore making the barrel of the burner of five-proof steel doesn▓t deny the possibility of the door of the burner premature burning. The results of the research of influences of the operating conditions of plasmatron and of the way of putting plasma jet into duct-coal flow allowed to place plasmatron in a coal-dust burner really sensibly. Simultaneously the field of burning in a near-wall adjacent strata moves towards the mouth of the burner and thus the process of furnace black formation on the wall is impossible and the high temperature zone of the flow moves behind the cut of the burner. It should be marked that in the whole the area of industrial researches the operators of block switchboard noticed the increase in the stability of boiler operation with plasma stabilization. The description of the results of industrial tests in details is submitted in application 3. The results of the definition of thermal fields in furnace area of the boiler and definition of concentration of harmful throw-ups during the operation of the boiler in a nominal position and with plasma stabilization showed that the temperature of the torch rise in the boiler by 100 √ 200 0C and NOx throw ups reduced by 18 √ 20 percent with plasma stabilization and fixed usage of air and dust (supplement 3). 4. THE MAIN CHARACTERS OF PLASMA TECHNOLOGY AND PLASMA EQUIPMENT The main criteria of and characters of plasma technology and plasma equipment were identified on the base of carried out industrial tests and mathematical modeling the process of coal burning stabilization results. It is established that the process of coal burning in the boiler furnace is radically changed with coal ignition in the burner. Apart from the intensification of the burning process in the barrel of the burner due to plasma interaction with coal dust, thermal exchange is intensified in the furnace as during going out of the burner already formed in the burner a high temperature torch, the speed of which is much higher than that of a cold-coal flow. Therefore thermal exchange in the burner increases and that of the temperature in the volume of the boiler▓s furnace does as well. For burning anthracitic dust coal whose ash constitutes 47 percent with heat of combustion 7900 Kcal/kg and the output of the volatile up to 2 percent rated power of plasmatron for coal ignition in one burner constitutes 700 KW. The power of the plasmatron rises up to 800 KW with reducing heating power of coal to 5000 Kcal a kilogram. Reducing power of the plasmatron up to 200 KW is possible by changing the conditions of letting plasma and coal dust in. Lighting up is not sensible while burning coal of marks ц Х д in the condition of full loading if its heating power is more than 4000 Kcal a kilogram. In the condition of discharge of the block in night time i.e. at with reducing power to 130 - 150 MW, black mineral oil burners switch on for stabilization and up to 12 ton of black mineral oil are burnt per hour. As the block is discharged in nocturnal time reducing power in this usage