Fuel combustion method. Methods for burning gaseous fuel Chamber Dust Fireings
Patent owners RU 2553748:
The invention relates to heat and can be used in furnaces and in heat generators of various types using organic fuel for burning.
The method of effective fuel combustion is known by separating the gas (combustion reaction products), for example, a method of separation of gases using membrane with a permeate removal to remove CO 2 from Patent Patent Products 2489197 (RU) Patent holder: Temnolodi End Membrane End Reerch, Inc., authors Baker Richard (US), Vidhmans Johanns Ji (US) and others.
The implementation of this combustion method is carried out in several stages: the carbon dioxide collection step, the gas separation stage, which is combined with compression and condensation to produce a product from carbon dioxide in the form of a liquid and a purge-based stage, in which the incoming air or oxygen is used for the furnace as purge gas. The disadvantage of this method is its complexity in the implementation, since it includes many additional steps of standard type, such as heating, cooling, compression, condensation, pump feed, various types of separation and / or fractionation, as well as pressure monitoring, temperatures, flows, etc. p., With this method, the capture of carbon dioxide comes from the exhaust flow formed by burning fuel, diluted with ballast gases, which has a reduced temperature due to this.
The closest technical solution (prototype) is a method of burning solid fuel in household heating furnaces on patent 2239750 (RU), authors Ten V.I. (RU) and ten years (RU), Patent holder Ten Valery Ivanovich (RU).
This method involves loading the fuel to the grille of the furnace, the creation of thrust in its workspace, ignition and combustion of fuel with the removal of burning products into the atmosphere, the control of thrust and the amount of combustion products removed from the furnace by opening the flap of the flap and the smoke pipe.
The disadvantage of this method of burning solid fuel is its complexity in the implementation due to the breakdown of the process into a number of individual periods, in each of which the fuel is minimized, adjusted to the intensive combustion mode and after reaching the desired furnace temperature, the combustion process is transferred to the attenuation mode, then Razhigi With the help of complex automation and using already liquid or gaseous fuel. The disadvantage of these and other similar methods of fuel combustion is mixing products of combustion, heat sources (CO 2 and H 2 O), in the reaction zone, into a single stream with ballast gases (nitrogen, excessive air, etc.), which worsen the conditions for burning fuel and use of highlighted heat (selective heat and take it into the atmosphere).
The present invention puts its task to improve the conditions for burning fuel and increase the volume of thermal energy released by fuel.
The technical result of the proposed method consists in an increase in the efficiency of furnaces and heat generators by burning combustible gases in the middle zone of the coach of the furnace and the removal of ballast gases from the burning zone, as well as due to the exposure to the hot carbon-overheated water vapor.
The proposed fuel combustion method is illustrated by the graphic material, where the following notation is taken: 1 - the burning reaction zone; 2 - pissed (asolnik); 3 - supply of primary air for ignition, maintain combustion and gasification of fuel (volatile combustible gases); 4 - Fuel combustion chamber; 5 - hydrocarbon (volatile gases); 6 - feeding secondary air to the combustion zone for burning volatile combustible gases; 7 - harmful non-combustible ballast gases that are not involved in burning; 8 - supply of superheated steam; 9 - Useful hot products - heat carriers, carbon dioxide and water vapor; 10 - heat exchange zone; 11 - grate grille; 12 - Gas yield from the oven cap.
The proposed method is carried out as follows. The solid fuel is loaded at the grille 11, it is ignition produce it, and the primary air comes through the primary air. Then after the ignition in the cap directly into the combustion zone comes secondary air 6 for burning volatile combustible gases. As a result of the combustion reaction, a mixture of non-interconnected gases arises: hot carbon dioxide and water vapor and conditionally cold ballast gases - excess air and freed nitrogen in its composition (excessive air with an increased nitrogen content). The feature of the cap design is that in it during the burning reaction there is a separation of emerging gases. Hot gases rise upwards, giving heat energy with a cap, and cold particles of ballast gases fall down through the cap zones with a reduced temperature. Fuel combustion reactions are expressed by known burning equations. The ratios of the reaction substances are withstanding, as well as their composition. That is, a carbon C, hydrogen H 2 with oxygen O 2 in an amount determined by chemical equations takes into the reaction.
other substances can not enter the reaction. The combustion reaction occurs in the combustion zone between the hydrocarbon and oxygen without the participation of ballast gases, while the nitrogen released from the air in the composition of excessive air, as less heated, pushed through the bottom of the cap outside (the output tube on the diagram is not shown). After heating the combustion chamber and the presence of hot carbon in it in the cap fill overheated water vapor 8 below the secondary air supply zone. As a result of carbon interaction with water vapors at high temperatures, combustible gases arise in accordance with known chemical equations.
under reduced temperature with a total positive thermal effect that enhances the process of burning fuel and increase heat transfer from it. The implementation of the proposed method of burning fuel will allow to increase the efficiency of the ovens and heat generators. The proposed method is quite easy to implement, does not require complex equipment and can be widespread in industry and in everyday life.
INFORMATION SOURCES
1. Patent of Russian Federation No. 2489197, IPC B01D 53/22 (2006.01). A method of separating gases using membranes with a permeate purge to remove carbon dioxide from combustion products. Patent holder, Temnolodzhi End Membrane, Inc. (US).
2. Patent of Russian Federation №2239750, IPC F24C 1/08, F24B 1/185. The method of burning fuel in household heating furnaces. Patent holder Ten Valery Ivanovich.
3. Manykel K. Furnaces and fireplaces. Reference manual. Translation from Finnish. M.: Stroyzdat, 1987.
4. Ginzburg D.B. Gasification of solid fuel. State Publisher Literature on Construction, Architecture and Building Materials. M., 1958.
The method of burning fuel in the furnaces having a cap with a fuel combustion chamber and a grate grid, which includes the loading of fuel, ignition, and burning fuel due to the primary air entering through attended, characterized in that the movement of gases in the cap is carried out without the use of pipe thrust, with the possibility of accumulating The hot gas in the top of the cap, while in the cap, directly into the burning zone, serve secondary air, and the hot gases rise upwards, giving the heat energy to the cap, and the cold particles of ballast gases are lowered down through the cap zones with a reduced temperature, after heating the chamber Combustion into it, below the supply of secondary air, fed overheated water steam on the hot carbon and get combustible gases.
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The invention relates to heat and can be used in furnaces and in heat generators of various types using organic fuel for burning. The technical result is an increase in the efficiency of furnaces and heat generators. The combustion method of fuel in the furnaces having a cap with a fuel combustion chamber and a grate grid includes loading of fuel, ignition and burning fuel due to primary air entering through pistened. The movement of gases in the cap is carried out without the use of pipe thrust, with the possibility of accumulating hot gases at the top of the cap. At the same time, secondary air is served directly into the combustion zone. Hot gases rise upwards, giving heat energy with a cap, and cold particles of ballast gases fall down through the cap zones with a reduced temperature. After heating the combustion chamber into it, below the supply of secondary air, the superheated water vapor is supplied to the hot carbon and the combustible gases are obtained. 1 il.
There are three ways to burn fuel: a layer, in which the fuel in the layer is blowing with air and burned; TAKE, when the fuel and air mixture combines in a suspended state when moving along the furnace chamber, and the vortex (cyclone), at which the fuel and air mixture circulates along the streamlined contour at the expense of centrifugal forces. The flare and vortex methods can be combined into a chamber.
Process solid fuel It occurs in a fixed or boiling layer (pseudo-liquefied). In a stationary layer (Fig. 2.6, but) Slices of fuel do not move relative to the lattice, under which the air required for burning is supplied. In a boiling layer (Fig. 2.6, b.) Particles of solid fuel under the action of high-speed air pressure are intensively moved by one relative to the other. The flow rate at which the layer stability is disturbed and the reciprocating movement of particles above the grille begins, called critical. The boiling layer exists within the boundaries of the velocities from the beginning of the pseudation to the pneumatic transport mode.
Fig. 2.6. Fuel combustion schemes: but - in a fixed layer; b. - in a boiling layer; in - torch forwarding process; g. - vortex process; d. - Structure of a fixed layer when burning fuel and change a, O. 2 , SO, SO 2 I. t. The thickness of the layer: 1 - lattice; 2 - slag; 3 - burning coke;
4- fuel; 5 - Support Flame
In fig. 2.6, d. The structure of the fixed layer is shown. Fuel 4, referred to burning coke, warms up. The distinguished volatile burns, forming the layered flame 5. The maximum temperature (1300 - 1500 ° C) is observed in the combustion area of \u200b\u200bcoke particles 3. In the layer, two zones can be distinguished: oxidative, a\u003e 1; Replacement, A.< 1.
In the oxidative zone of fuel and oxidizer reaction products are like SO 2 and SO. As the air is used, the rate of education SO 2 slows down, its maximum value is achieved with an excess of air a \u003d 1. In the reducing zone due to the insufficient amount of oxygen (a< 1) начинается реакция между SO 2 and burning coke (carbon) with education SO. Concentration SO in combustion products increases, and SO 2 decreases. Zone length depending on the average size d K. Fuel particles Next: L. 1 = (2 – 4) d K.; L. 2 = (4 – 6) d K.. On zone lengths L. 1 I. L. 2 (in the direction of their reduction) affect the increase in the content of volatile combustion, decrease in ash A R., Air temperature growth.
Since in zone 2 except SO Contains N. 2 I. SN 4, the appearance of which is associated with the release of volatile, then for their afterburning, part of the air is supplied through blowing nozzles located above the layer.
In a boiling layer, large fuel fractions are in suspended state. Boiling layer can be high-temperature and low-temperature. Low-temperature (800 - 900 ° C) Fuel combustion is achieved when the boiler heating is placed in a boiling layer. Unlike a fixed layer, where the size of the fuel particles reaches 100 mm, crushed coal is burned in a boiling layer d K.£ 25 mm.
The layer contains 5 - 7% fuel (by volume). The heat transfer coefficient to the surfaces located in the layer is quite high and reaches 850 kJ / (m 2 × h × K). When burning minorial fuels for increasing heat transfer in the layer, fillers are introduced in the form of inert granular materials: slag, sand, dolomite. Dolomit binds sulfur oxides
(up to 90%), as a result of which the likelihood of low-temperature corrosion is reduced. The lower level of gases in the boiling layer helps reduce the formation in the process of combustion of nitrogen oxides, during the emission of which the environment is polluted into the atmosphere. In addition, the laying of screens is excluded, i.e., sticking on them the mineral part of the fuel.
A characteristic feature of the circulating boiling layer is approximation to the operation of the layer in the mode of pneumatic transport.
Chamber of solid fuel combustion It is carried out mainly in powerful boilers. In case of chamber burning, the grinding to the dusty state and the pre-dried solid fuel is supplied with part of the air (primary) through the burners in the furnace. The rest of the air (secondary) is introduced into the burning zone most often through the same burners or through special nozzles to ensure complete combustion of fuel. In the furnace, dust-like fuel is lit in suspended state in the system of interacting gas-air flows moving in its volume. With a larger chopping of fuel, the area of \u200b\u200bthe reacting surface is significantly increasing, and therefore chemical combustion reactions.
The characteristic of the grinding of solid fuel is the specific area F PLdust surfaces or total surface area of \u200b\u200bdust particles weighing 1 kg (m 2 / kg). For particles of spherical shape of the same (monodisperse) size size F PLinversely proportional to the diameter of dust.
In fact, the dust obtained during grinding has a polydisperse composition and complex shape. To characterize the quality of the grinding of polydisperse dust, along with the specific surface area of \u200b\u200bdust, the results of its sifting on the sizes of various sizes are used. According to the sifting data, they build a grain (or a grossable) dust characteristic as a dependence of the residues on the sieve sieve sieve. And more often use indicators of the residues on sines 90 μm and 200 μm - R. 90 I. R. 200. Pre-preparation of fuel and air heating ensure the burnout of solid fuel in the furnace for a relatively short period of time (a few seconds) of dusty flows (torches) in its volume.
Technological methods of combustion organization are characterized by a certain introduction of fuel and air in the furnace. In most dust preparation systems, the transportation of fuel in the furnace is carried out by primary air, which is only part of the total air required for the combustion process. The supply of secondary air in the furnace and the organization of interaction with primary is carried out in the burner.
The chamber method, in contrast to the layer, is also used for burning gaseous and liquid fuel. Gaseous fuel enters the flue chamber through a burner, and liquid - through the nozzles in the sprayer.
Layer furnaces
A fixed layer firebox can be manual, semi-mechanical or mechanical with a chain grid. Mechanical furnace Called a layer coil, in which all operations (fuel supply, slag removal) are performed by mechanisms. When servicing semi-tech furnaces, along with mechanisms, manual work is used. Distinguish the fireboxes with direct (Fig. 2.7, but) and inverse (Fig. 2.7, b.) Stroke of grilles 1, driven by asterisks 2. The fuel consumption supplied from the bunker 3 is adjustable to the height of the slide setting 4 (see Fig. 2.7, but) or movement speed of the dispensers 7 (Fig. 2.7, b.). In reverse lattices, fuel is fed on the canvas 10 mechanical conversion (Fig. 2.7, b, B.) or pneumatic (Fig. 2.7, g.) type. Small fractures are combined in suspended state, and large-in layer on the grid, under which air is supplied 9. Heating, ignition and combustion of fuel occur due to heat transmitted by radiation from combustion products. Slag 6 with a slag seater 5 (Fig. 2.7, but) or under the action of its own weight (Fig. 2.7, b.) Enters the slag bunker.
The structure of the burning layer is presented in Fig. 2.7, but.Region III burning coke after zone II. heating the incoming fuel (zone I.) Located in the central part of the lattice. Here is the restorative zone IV.The unevenness of the degree of combustion of fuel along the lattice length leads to the need for a sectional supply of air. Most of the oxidizing agent must be supplied to the zone III, smaller - to the end of the coke response zone and a very small amount - to the zone II. Fuel preparation for burning and zone V.burning slag. This condition corresponds to the stepped distribution of an excess air a 1 along the lattice length. The supply of the same amount of air in all sections could lead to increased air excess at the end of the lattice canvase, as a result of which it will not be enough for coke combustion (curve A 1) in the zone III.
The main disadvantage of the chain grilles is increased heat loss from fuel combustion incompleteness. The scope of such lattices is limited to boilers with steam-performance D. \u003d 10 kg / s and fuels with volatile output \u003d 20% and listed moisture.
Flakes with a boiling layer are distinguished by a reduced emission of such harmful compounds as No H., SO. 2, low probability of screens, the possibility (due to the low temperature of gases) saturation of the grain volume of the heating surfaces. The shortcomings are the increased infidel on the combustion of fuel, high aerodynamic resistance of the lattice and layer, a narrow range of control of the boiler.
Fig. 2.7. Schemes for the chain grilles and types of fuel relief: but, b. - fireboxes with direct and refunds of the grid, respectively; in, g. - mechanical and pneumatic reliefs;
1 - lattice; 2 - asterisks; 3 - bunker; 4 - Sewber; 5 - slag; 6 - slag; 7 - fuel dispenser; 8 - retirement; 9 - air supply; I - fresh fuel zone; II - fuel heating zone;
III - the area of \u200b\u200bburning (oxidation) of coke; IV - reducing zone; V - fuel burning zone
The fuel combustion method is characterized by relatively low combustion process rates reduced by its efficiency and reliability. Therefore, he did not find use in high performance boilers.
Chamber deductive furnaces
Chamber of dust carbon blacks consist of dust burners and a fiber chamber.
Floor chamber The device is called to complete the combustion process and isolation from external conditions.
Burners Designed to enter fuel and air stirring and stirring, ensuring stable ignition and burnout of the mixture. They must meet the following requirements: Tightness of the joint compound; maintainability; Provide sustainable burning on a reduced load and when using backup fuel (gas or fuel oil).
Fireings for burning solid fuels according to the method of outputting slag are separated on the furnaces with dry slag homing (Fig. 2.8) and liquid slascation furnaces (Fig. 2.9).
In fig. 2.8 shows a schematic diagram of torch (deductive) furnaces with dry slag desiccation, where the fuel combines a suspended state in the volume of the furnace chamber.
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In the furnaces with dry slag adoration of the torch core, there are slightly below the heat chamber coated with on-screen heating surfaces, perceiving radiated combustion and burning torch heat and protecting the walls of the heat chamber from exposure to high temperatures. Such furnaces are performed by single-chamber with a cold funnel at the bottom. In the zone of the cold funnel and in the upper part of the combustion products in the top of the combustion products than in the torch core. Weighted particles of ash particles weighted in the flow gases, getting out of the torch kernel in the region of relatively low temperatures, are cooled and harden. A small part of the ash (10-15% of the total ashty of the fuel) falls into the slag bunker, located under the cold funnel. The remaining ash is carried away with combustion products in the boiler gases.
Liquid slascation furnaces are single-chamber and two-chamber.
In the single-chamber bottom of the heat chamber are performed in the form of a horizontal or inclined feed. At an altitude of 4-5 meters, the screens are closed with thermal insulation material to reduce heat-perception, which allows you to maintain high temperatures of 1500 - 1600 o C, in which the slag is in a liquid state. The liquid slag is continuously removed through the pilot into the slag bath, filled with water.
In two-chamber furnaces, the combustion processes of fuel and cooling products of combustion are separated.
Circuit diagrams of two-chamber cyclone fuels with liquid looseness are shown in Fig. 2.9. The basic components of cyclone fuels are the vortex combustion chamber, which is a cylinder with a tangential focused or dispersed input of fuel and air, and a casing cooling chamber of a prismatic form.
Fuel is served in a vortex chamber with primary air. The fuel and air mixture through the swirl (snail) is introduced into the central part of the chamber. Droblenka is introduced along the axis. Through the tangentially located nozzles, coal dust comes. Secondary air is fed to the chamber tangentially through the nozzle-slot at high speed (more than 100 m / s), ensuring the movement of fuel particles to the chamber walls. The vortex formed in the cyclone chamber contributes to the intensive formation of the fuel and air mixture and the combustion of fuel both in the volume of the cyclone and on its walls. Between the combustion and cooling chambers there is a slag-waving bundle of lined (closed insulating material) of pipes, designed to capture the molten slag droplets contained in combustion products. Unpattage particles of ash solidify in the cooling chamber.
The walls of the combustion chamber for insulation are performed from the wrong screens covered with refractory coating (Fig. 2.10), and the walls of the cooling chamber have laptile smooth-tube or fin screens.
Depending on the principle of organizing the process of entering a dusty mixture, dust bodies can be divided into three types: vortex, straight-flow and flat-brake.
Principle of operation of the vortex burner (Fig. 2.11, but) Next. Primary flows I. and secondary II. Air is injected into the furnace through the ring concentric channels in which swirpers are installed. The direction of the stream stream is the same. A characteristic feature of such a flow is a comparability of the magnitude of all three components of speed: axial (longitudinal) w A.tangent w T.(district) and radial w r.The presence of a tangent component of the speed leads to a noticeable expansion of the jet forming a parabolic sprout in the space. In the central inner part of the 1strion, the area of \u200b\u200bthe vacuum is formed, the value of which is determined by the sleeve attitude t \u003d D O / D Aand the speed of streams at the outlet of the burner.
Under the action of pressure drops, the inverse currents of high-temperature combustion products arise, providing stabilization of the ignition of the dusty mixture. When moving primary I. and secondary II. The air is mixed, and the combustion process applies to the outer surface of the 2rd.
Depending on the design of the swirpers, the burners are low-blade (Fig. 2.12, in), sniron and sniffinary (Fig. 2.12, but), bladder-blade, direct-and-smoke (Fig. 2.12, b.) And directive blade. In the title, first indicate the type of swirl in the primary air.
Fig. 2.12. Types of vortex dust burners: but - Uphilous and low-voltage burner;
b. - Direct-term and street burner OrGRs; in - Uphilous-blade burner CCTI - TKZ;
1 - snail dusty mixture; 1 "- the inlet nozzle of the dusty mixture; 2 - Snail of secondary air; 2" - the input box of secondary air; 3 - ring channel for the outlet of the dusty mixture in the furnace; 4 - the same for secondary air; 5 - main fuel oil nozzle;
5 "- a damask fuel oil; 6 is a divider at the outlet of the dusty mixture;
7 - Swirl blades for secondary air; 8 - supply of tertiary air along the axial channel; 9 - control of the position of the divider; 10 - axial flux of air;
11 - furnishings of the furnace; AB - the boundary of the ignition of the dusty mixture; B - SUPPROOM OF THE FREE GAS TO THE REDUCH OF TORK
In the vortex burner, the primary supply I. and secondary II. Individual air (Fig. 2.11). Submission of secondary air can be both the upper and lower, and the supply of primary air is only the top, which is due to the need to prevent dust deposits in the dust pipeline. The channels of primary and secondary air are performed by ring concentric.
The disclosure of the torch, the amount of ejectable gases, the distribution of speeds, the range in the vortex burner is determined by the intensity of the flux twist, which is estimated by the parameter pcock, depending on the design of the swirl.
Through the vortex burners, it is advisable to supply all types of fuel, except for the milling peat. The disadvantages of these burners include: increased hydraulic resistance, constructive complexity, the need to perform the output part from heat-resistant materials to avoid its burnout, increased tendency to separation of fuel, somewhat larger (compared to the burners of other structures) emissions of nitrogen oxides into the atmosphere.
In the direct flow burners, in contrast to the vortex streams of the primary I. and secondary II. The air is not twisted and have a unidirectional (associated) movement (Fig. 2.11, b.). The tangent component of the speed is absent, but a radial much less longitudinal component.
Inflammation stabilization is carried out thanks to the ejection of combustion products 1 along the periphery of the 2rd. The desired degree of mixing air is achieved by the corresponding ratio of the primary speeds. I. and secondary II. air.
The resistance of the direct flow burners is less than the vortex, they are simpler in the manufacture, the amount of nitrogen oxides formed is less. The disadvantages of the direct flow burners include higher rangeliness and worst mixing conditions of the mixture compared to vortex.
The scope of straight-flow burners - stone and brown coals. Pre-mixing burners having a mixing chamber are used mainly for peat and brown coal.
The principle of operation of the plane-fake burners (Fig. 2.13) is based on the use of the effect of the collision of two air jets directed at an angle to each other. The range of the torch of the plane-facade burners is less than that of the direct flow. A triangle is formed between the jets of the secondary air and the burner, which is supplied with fuel flammable by ejected into it hot combustion products. As a result of the expansion of the jets after collision, a flat jet is formed, which has a large surface. Due to the expansion of the jet in one plane and intensive ejection, the combustion products from below and on top of the jet speed drops sharply. The torch's slope is regulated by changing the ratio of secondary air expenditures supplied to the upper and lower nozzles. This property of the burner is used when changing the quality of the fuel burned, as well as the load of the boiler unit or its mode.
Liquid fuel combustion furnaces (fuel oil)
As a liquid fuel for industrial boilers, it is used mainly by fuel oil. In order to burn the fuel oil, it must be pre-sprayed to improve the conditions of evaporation, since gaseous products of its evaporation are burning with fuel oil. For spraying and entering fuel oil to the furnace use special devices, called injectors.
The fuel oil combustion furnace consists of a fiber chamber, refective surfaces of heating and nozzles.
The furnace chamber and the emission surfaces of the heating during the combustion of the fuel oil are made so that the bottom of the chamber is limited to horizontal or slightly inclined pallet. The chamber itself is made relatively smaller sizes, since the fuel oil can be burned with a significantly higher thermal stress of the flue space than dust-like fuel. In the boilers, small steam outputs are often not shielded to simplify the execution of the screen system.
1 Types of fuel
Solid fuel - combustible substances, the main component of which is carbon. Solid fuel attributes stone coal and brown coals, combustible shale, peat and wood. The properties of fuel are largely determined by its chemical composition - the content of carbon, hydrogen, oxygen, nitrogen and sulfur. The same amounts of fuel are given when burning a different amount of heat. Therefore, to assess the quality of fuel, its calorific value is determined, that is, the greatest amount of heat released in full combustion of 1 kg of fuel (the largest calorific value of the coal). Mostly solid fuel is used to obtain heat and other types of energy, which are spent on receiving mechanical work. In addition, more than 300 different chemical compounds can be obtained from solid fuel at its appropriate processing (distillation), the processing of brown coal into valuable types of liquid fuel - gasoline and kerosene is of great importance.
Briquettes
Briquettes are a solid fuel formed in the process of compressing woodworking process (chips, chips, wood dust) as well as household waste (straw, husk), peat.
Fuel briquettes are convenient for storage, in the manufacture of harmful binders are not used, because this type of fuel is environmentally friendly. When burning, they do not spark, do not distinguish the gas gas, they burn evenly and smoothly than enough long combustion process in the boiler chamber. In addition to solid fuel boilers, used in home fireplaces and for cooking (grilled for example).
There are basic 3 types of briquettes:
1. RUF.-Brequets. Folded "bricks" rectangular shape.
2. Nestro. -Brequets. Cylindrical shape can also be with holes inside (rings).
3. R.iNI.& Kau - briquettes. Faceted briquettes (4,6,8 faces).
Advantages of fuel briquettes:
Environmentally friendly.
Long and convenient storage. Due to heat treatment is not affected by fungi. And thanks to the formation is conveniently used.
Long and even combustion is due to the high degree of density of briquettes.
High calorificness. Almost two times higher than that of ordinary firewood.
Permanent combustion temperature. Due to uniform density.
Economically beneficial.
Minimum ash after burning: 1-3%
Pellets or fuel granules.
In essence, the principle of production is that and briquettes. Lignin is used as a binder (vegetable polymer).
Materials are the same as the briquettes: bark, chips, straw, cardboard. First, the raw material is crushed to the state of pollen, then after drying, a special granulator forms a special form granules. Used in pellet boilers heating. The prices of solid fuel of this species are the highest - this is justified by the complexity of production and popular with buyers.
The following types of this solid fuel distinguish:
Recycling Rounds of solid and soft trees in pellets.
Peat pellets
Pellets obtained as a result of recycling of sunflower husks.
Pellets from straw
Benefits Pellet:
Environmentally friendly.
Storage. Pellets thanks to special production technologies can be stored right in the open sky. They do not swell, do not be covered with fungus.
Long and smooth burning.
Low cost.
Thanks to small shape, pellets are suitable for boilers with automatic loading.
Wide range of applications (boilers, furnaces, fireplaces)
Firewood
Wooden pieces designed to obtain heat by burning in boilers for heating on solid fuel, furnaces provided for firewood. For convenience, the length of the lane is most often 25-30 cm. For the most efficient use, "the lowest possible level of moisture is required. For heating, it is necessary as slow combustion as possible. Also in addition to heating, firewood can be used for example in boilers for solid fuel. Best for these parameters Large breeds are suitable: oak, ash, wood, hawthorn, birch. Worse - coniferous firewood, as they contribute to the deposition of the resin and have low calorific value, while they quickly go beyond.
Firewood is represented by two species:
Sawn
Cheerful.
2 Fuel composition
For the formation of coal, the abundant accumulation of vegetable mass is necessary. In the ancient peat swamps, starting from the Devonian period, the organic substance was accumulated from which fossil coals were formed without access of oxygen. Most of the industrial fossil coal deposits are related to this period, although more young deposits exist. The age of the most ancient coals is estimated at about 350 million years. Coal is formed under conditions when the rotting vegetable material accumulates faster than its bacterial decomposition occurs. The ideal setting for this is created in the swamps, where there is a stumbling water depleted with oxygen, prevents the vital activity of bacteria and thereby protects the vegetable mass from complete destruction? At a certain stage of the process, the acids allocated during its course prevent further activity of bacteria. So peat occurs - the source product for the formation of coal. If then its burial occurs under other nanos, the peat is experiencing compression and, losing water and gases, is converted to coal. Under the pressure of precipitation layers with a thickness of 1 kilometer from a 20-meter peat layer, a layer of brown coal with a thickness of 4 meters is obtained. If the depth of the burial material reaches 3 kilometers, then the same layer of the peat will turn into a layer of stone coal with a thickness of 2 meters. At greater depth, about 6 kilometers, and at a higher temperature, the 20-meter peat layer becomes a 1.5 meters thick anthracite layer. In the results of the movement of the earth's crust, coal layers were lifted and folding. Over time, the elevated parts were collapsed due to erosion or self-burning, and the omitted persisted in wide shallow pools, where coal is at a level of at least 900 meters from the earth's surface.
Brown coals. Contain plenty of water (43%), and therefore have low heat of combustion. In addition, contain a large number of volatile substances (up to 50%). They are formed from the dead organic residues under the pressure pressure and under the action of elevated temperatures at depths of about 1 kilometer.
Stone coals. Contain up to 12% moisture (3-4% internal), so they have a higher heat of combustion. Contain up to 32% of volatile substances, due to which they are well flammable. They are formed from brown coal at depths of about 3 kilometers.
Anthracites. Almost entirely (96%) consist of carbon. Have the greatest warmth of combustion, but badly flammable. Are formed from stone coal and in the form of oxidesBUT h.. They relate to the harmful components of combustion products, the number of which should be limited.
Sulfur - contains in solid fuel in the form of organic compoundsSO. and cchedanS. x. They are combined into a volatile sulfurS. l.. Even sulfur is part of the fuel in the form of sulfur salts - sulfates - not able to burn. Sulfate sulfur is accepted to belong to the ash of fuel. The presence of sulfur significantly reduces the quality of solid fuel, as sulfur gasesSO. 2 andSO. 3 Connecting with water form sulfuric acid - which in turn destroys the metal of the boiler, and falling into the atmosphere harms the environment. It is for this reason that the sulfur content in fuel is not only in solid - extremely undesirable.
The ash - fuel is a ballast mixture of various minerals remaining after full combustion of the entire fuel part of the city. The ash directly affects the quality of the combustion of fuel - reduces burning efficiency.
Questions:
1. What are the main types of solid fuel?
2. What is ash?
3 Applying fuel
The use of stone coal is diverse. It is used as domestic, energy fuel, raw materials for the metallurgical and chemical industry, as well as to extract rare and scattered elements from it. Liquefaction (hydrogenation) of coal with the formation of liquid fuel is very promising. For the production of 1 ton of oil, 2-3 tons of stone coal are consumed, some countries have almost fully ensured themselves with fuel due to this technology. Artificial graphite is obtained from stone coals.
From the stone coal, the brown coal is extremely distinguished by the color of the feature on porcelain plastic - it always brings. The most important difference from the coal is to the smaller carbon content and much greater content of bituminous volatile substances and water. This explains why the brown coal is easier to burn, gives more smoke, the smell, as well as the aforementioned reaction with caustic potassium and highlights little heat. Due to the high water content for burning, it is used in a powder into which it inevitably turns when drying. Nitrogen content is significantly inferior to stone coals, but the elevated sulfur content.
The use of brown coal - like fuel, brown coal in many countries is consumed significantly less than the stone coal, however, due to low cost in small and private boilers, it is more popular and sometimes takes up to 80%. It is used for dust-like combustion (when stored, brown coal dries and crumbles), and sometimes entirely. On small provincial CHP, it is also often burned to obtain heat. Modo in Greece and especially in Germany, brown coal is used in steam power plants producing up to 50% of electricity in Greece and 24.6% in Germany. At high speed, the preparation of liquid hydrocarbon fuels from brown coal with distillation is propagated. After distillation, the residue is suitable for producing soot. From it remove combustible gas, carbon reagents and methane wax (mountain wax) are obtained. In meager quantities, it is used for crafts.
Peat - fuel is mineral, sampled in the process of natural diefing and incomplete decay of swamp plants in conditions of excess moisturizing and difficult air access. Peat is a product of the first stage of the angle of the educational process. The first information about the peat as a "combustible land" used for cooking belongs to the 26th century of our era.
The sedimentary breed of plant origin consists of carbon and other chemical elements. The composition of coal depends on the age: older than all anthracite, younger than stone coal, the most young. Depending on the aging, it has different moisture. And younger - the more moisture. Coal in the process of burning pollutes the environment, plus it sinters into the slag and settles on the cooler in the boiler. This in prevents normal burning.
Questions:
Fuel Application Area?
Does the enforcement of the fuel burning in the environment and what kind of the most ?
4 Fuel combustion methods
There are three fuel combustion methods: a layered, torch or chamber and vortex.
1 - grate and grate; 2 - door stobnant; 3 - boot door; 4 - heating surfaces; 5 - heat chamber.
Figure 4.1 - Scheme of layer firebox
This drawing shows a layered method of burning fuel, where the layer of lump fuel lies motionlessly on the grille and is blocked by air.
The layer method is used to burn solid fuel.
And here shows a flare and vortex method of burning fuel.
1 - burner; 2 coaching chamber; 3 - icing; 4 - flue screen; 5 - Ceiling radiation superheater; 6 - Feston.
Figure 4.2 - Chamber Firm
Figure 4.3 - Vortex Fuel Burning Method
With a torch and vortex method, all types of fuel can be burned, only solid fuel is pre-exposed to different, turning it into dust. When burning fuel, all heat is transferred to combustion products. Such a temperature is called the theoretical temperature of burning fuel.
In industry for burning solid fuels used boilers of continuous action. The principle of continuity is maintained at the expense of a grate grid, which is constantly fed solid fuel.
For more rational fusion of fuel, boilers are constructed, which are able to burn it in a dusty state. The liquid fuel is also burned in the same way.
Questions:
What is the most rational combustion?
Explain the advantages of the chamber method of burning.
5 Workflows in boilers
Workflows in boilers:
Para formation
In boiler installations occur such processes as a steam formation:
Conditions under which steam formation occurs in boilers - constant pressure and continuous supply of heat.
Stages of the steam formation process: heated water to saturation temperature, vaporization and steam heating to a given temperature.
Even in boilers, it is possible to observe the corrosion of heating surfaces:
The destruction of the metal under the action of the environment is called corrosion.
Corrosion on the part of the combustion products is called outer, and on the side of the heated medium - internal.
There is low-temperature and high-temperature corrosion.
To reduce the destructive corrosion force, it is necessary to monitor the water boiler mode. So raw water before use forfood boilers are pre-treated in order to improve its quality.
The quality of the boiler water is characterized by a dry residue, a total singeling, rigidity, alkalinity and content of corrosionactive gases
Sodium-cationic filter - where water purification occurs
Deaerator - the removal of aggressive tools, air oxygen and carbon dioxide occurs.
Pipe samples that are outside and inside undergo corrosion.
Corrosion of heating surfaces
The internal corrosion of steam and water boilers is mainly the following types: oxygen, steaming, alkaline and submissible.
The main appearance of oxygen corrosion is ulcers, usually with iron oxides.
Conductive corrosion is observed when boilers with increased heat loads. As a result of this corrosion, on the inner surfaces of screen pipes and fragile damage in the places of evaporation of the boiler water.
As a result of submissive corrosion, shells are formed.
Outdoor corrosion can be low-temperature and high-temperature.
Low-temperature corrosion can occur when burning any fuel. High-temperature corrosion can occur when burning fuel oil.
The combustion of fuel is a chemical process of connecting its combustible elements with air oxygen flowing at high temperature and accompanied by the release of a significant amount of heat. Depending on the type of fuel distinguish Homogenic, heterogeneous burning and pulsating (pulsar). Homogeneous burning occurs in the volume (in mass), while the fuel and oxidizer are in the same aggregate state (for example, gaseous fuel and air). Heterogeneous burning flows on the surface of the separation of two phases, that is, when burning solid and liquid fuel. There are two ways of burning: in a layer of lump fuel and in a torch of dusty fuel (layer and flare methods of burning). Gaseous and liquid fuel are burned only in a torch. The method of supplying air to fuel is essential when combining it in a torch. The total combustion time T is determined by the time of mixing TD and the time of flowing chemical combustion reactions TK. Since it is possible to impose these stages of processes, the total combustion time T \u003d TD + TK.
A device intended for fuel combustion is called flage. Classification: according to the combustion of fuel- layers, chamber (torch) and cyclone; Only solid fuel are burned in the layer, and in other cases - solid, liquid and gaseous; according to the fuel supply mode- with periodic and continuous feed; by the relationship with the boiler- internal, i.e. located inside the boiler, remote, suitable outside the heated surface of the boiler; according to the method of supplying fuel and organization of service- manual, semi-mechanical and mechanical. Fuel Burning Fixesthere may be the following varieties: a) furnaces with a fixed grateproof grid and still lying on it layer of fuel; b) fireboxes with a fixed grateproof grid and a fuel layer moving on it; c) furnaces with a moving grate with a moving grille moving layer of fuel lying on it . Manual topka With a horizontal fixed grate grid, it allows you to burn all types of solid fuel when manually maintaining the operations of loading, shook and remove slag, applied in boilers of 1-2 t / h. Fires with an unbreakable bar: During the course, it moves the fuel from the loading rebound of the heating of the furnace and resets the slag from the grille, and at the reverse course, turn the fuel layer. but - Handman with a horizontal grate grid; b -the furnace with the preloader on the stationary layer; in- firing with an adhesive plank; g.- Fire with an inclined grate grid; d.- the furnace of the Pomerantsev system; e - firebox with a chain mechanical grid; j.- the same reverse stroke and the conversion; z.- chamber furnace for dusty fuel; to- furnace for burning liquid and gaseous fuels Fireings with an inclined grate grid. In them, the fuel is loaded into the furnace from above, as the gravity is burned under the action of gravity, slides into the lower part of the furnace, creating the opportunity to enter new portions of fuel to the furnace (2.5-20 t / h). High-speed mine furnaces of the system V. V. Pomeranssev Used for burning a slicing peat under boilers with steam-capacity up to 6.5 t / h. Fireings with a moving grate grid. These include furnaces with a mechanical chain grid of direct and reverse stroke. The chain lattice of the direct stroke moves from the front wall of the furnace to the rear, while the fuel is coming to the grate grid. (10-150 t / h). In chamber furnaces The fuel is burned in the form of coal dust. It is fed into the mixture with air to the furnace, where it burns in suspension. Chamber furnacesfor liquid and gaseous fuel.Apply direct-flow and vortex burners. The operation of the furnace is characterized by the following indicators: thermal power, heat loads of the grate grid and flue volume, useful action coefficient.
If the determining parameter take the speed of air w.in relatively speed of fuel particles v.t, then this parameter allocate four fuel combustion technologies.
1. In a dense filter layer(w. In \u003e\u003e v. T).
It is used only for slicing solid fuel, which is distributed on a grate grid. The fuel layer is blown with air at a rate at which the stability of the layer is not disturbed and the combustion process has an oxygen and reductive zone.
Visible thermal voltage of the grate grid is Q R.\u003d 1.1 ... 1.8 MW / m 2.
2. In a boiling or fluidized bed(w. in\u003e v. T).
With an increase in air speed, the dynamic pressure can achieve, and then exceed the gravitational force of the particles. The stability of the layer will disturb and the disorderly movement of particles will begin, which will rise above the grille, and then make a reciprocating movement up and down. The flow rate in which the stratum stability is disturbed is called critical.
An increase in it is possible to the velocity of the particles when they are taken out by the stream of gases from the layer.
A significant portion of air passes through a boiling layer in the form of "bubbles" (gas volumes), strongly mixing the fine-grained material of the layer, as a result, the process of burning in height proceeds by almost the constant temperature, which ensures complete fuel burnout.
For a boiling fluidized bed, air velocity is characterized by 0.5 ... 4 m / s, the size of the fuel particles is 3 ... 10 mm, the height of the layer is not more than 0.3 ... 0.5 m. Thermal voltage of the furnace Q V.\u003d 3.0 ... 3.5 MW / m 3.
A non-flammable aggregator is introduced into the boiling layer: small quartz sand, chamotte crumb, etc.
The fuel concentration in the layer does not exceed 5%, which allows you to burn any fuel (solid, liquid, gaseous, including combustible waste). The non-combustible filler in the boiling layer can be active in relation to harmful gases generated during combustion. The introduction of filler (limestone, lime or dolomite) makes it possible to translate into a solid condition to 95% sulfur gas.
3. In air flow(w. in ≈ v. T) or a flame forwarding process. Fuel particles turn out to be suspended in the gas-high-stream and begin to move with it, burning while driving within the fuel volume. The method is characterized by weak intensity, stretched burning area, harsh non-erosity; A high temperature of the medium in the ignition zone and thorough fuel preparation (spraying and preliminary mixing with air) are required. Heat voltage of the volume of the furnace Q V.≈ 0.5 MW / m 3.