RU2557967C1 - Powdered fuel combustion method - Google Patents

Abstract

FIELD: power industry.SUBSTANCE: air is separated using the method of nitrogen adsorption by zeolite, the first air flow enriched with oxygen and the second air flow enriched with nitrogen emitted from zeolite surface by its heating are formed, then the second air flow is separated into the main and additional flows, the additional flow is mixed with powdered fuel and the mix is supplied in the beginning of the ignition chamber. The part of mix of additional air flow and powdered fuel is supplied through the plasmatron to the ignition chamber where the flare of gasification of part of powdered fuel is formed in conditions of lack of oxygen, from the first air flow a part is separated and by means of the air tapping pipe supplied to the ignition chamber downstream the output cut of the plasmatron, downstream the plasmatron the flare of ignition of part of the powdered fuel formed in the plasmatron which ignites the mix of additional air flow and powdered fuel, the burning products from the ignition chamber are mixed with the main air flow and at lack of oxygen it is supplied into the combustion chamber, the rest of the first flow enriched with oxygen is supplied into the air preparation chamber where it is treated with the laser radiation of the solid-state laser with the wavelength 762±0.5 and/or 1268±0.5 nm, that induces the transition of oxygen molecules from the main electronic state into the excited singlet stateby supply of laser radiation into the cylindrical air treatment chamber with mirror surface, at least, in one place at the angle to its surface, smaller than the angle of full reflection from the mirror surface of the cylindrical air treatment chamber along the spiral polygonal curve with the step between the neighbouring turns of the spiral polygonal line, larger than the linear overall dimension measured along the axis of the cylindrical air treatment chamber, the treated part of the first air flow with singlet oxygen is supplied through the coaxial punched partition to the near-wall area of the combustion chamber, thus increasing the concentration of singlet oxygen towards the outlet from the combustion chamber.EFFECT: decrease of toxic emissions and improvement of process of combustion of powdered fuel.2 dwg

Description

The invention relates to the field of energy, in particular to methods for preparing and burning solid fuel, mainly pulverized fuel.

A known method of preparing air by adsorbing it into two streams enriched with oxygen and nitrogen (see. Overview. Inform. "Obtaining oxygen and nitrogen by adsorption separation of air." Authors VN Glupanov, Yu.I. Shumyatsky, Yu.A. Seregin, S. A. Brekhner. - M .: [b.i.], 1991. - 47 pp., Ill. - (Industrial and San. Gas Treatment. XM-14 Series: Overview. Inform. TsINTIKHIMneftemash). The disadvantage of this method is the incomplete information on the ways and means of using the proposal in thermal installations.

There is a method of preparing air for the operation of the combustion chamber of a gas turbine engine, namely, that fuel and air are separately supplied to the combustion chamber, the air flow is divided into two parts, the primary air flow is mixed with fuel and ignited in the cavity of the flame tube, the walls are cooled by the secondary air flow the flame tube, while acting on the flow of secondary air and feed it through the holes in the wall of the flame tube of the combustion chamber, and the impact on the flow of secondary air before it is fed into the chamber Gorania is carried out by laser radiation with the possibility of excitation of molecular oxygen in a singlet state with multiple passage of laser radiation between the mirrors (see RF patent No. RU 2505749 C1, applicant Federal State Unitary Enterprise "Central Institute of Aviation Motors named after P.I. Baranov", publ. 01/27/2014). The main disadvantage of the known method of processing air is the presence of mirrors from which the laser beam is reflected, and high losses during multiple reflection, which does not allow to create a reliable field of laser radiation, since the mirrors themselves are in the zone of high temperature exposure and are cooled by the air flow, and the reflection places The laser beam is still heated due to absorption of part of the laser radiation, which destroys the surface of the mirrors.

A known method of burning pulverized fuel (see AS USSR No. 1774131, the applicant "Enterprise" URALTECHENERGO "production association for commissioning, improving the technology and operation of power plants and networks" SOYUZTECHENERGO, publ. 07.11.1992), which describes the process with stage-by-stage supply of several air-fuel mixture flows with different relative fuel contents in them. The main disadvantage of this method is that in the streams with a low content of pulverized coal to increase the stability of combustion add a second type of fuel - gas.

A known method of burning pulverized fuel (see patent for the invention of the Russian Federation No. 2153633, applicant Open Joint-Stock Company "All-Russian Thermotechnical Research Institute", published on 07.27.2000), which describes a method of preparing air and solid fuel and burning it, including the separation of air into two streams, the formation of the first stream, the formation of the second stream, in which there is an excess of air, part of the air is separated from the first stream, a third stream enriched in fuel is formed into which it is pulverized solid fuel and transport it to the beginning of the ignition chamber, and part of the solid is fed through a plasma torch, where a gasification torch of part of the solid fuel is formed under conditions of an oxidizer deficiency, part is separated from the second stream and a fourth stream enriched with oxygen from the air is fed, which is fed to the end of the chamber and formed the ignition torch of the combustion of a portion of gasified fuel, the combustion products of which are supplied to the main part of the first stream carrying the pulverized solid fuel, ignite it and feed into the combustion chamber. The main disadvantage of this method is that the plasma torch treats air with a relatively high content of supposedly neutral nitrogen, which is ballast and does not affect the process of maintaining combustion in the flame stabilization flame, however, passing through the plasma torch, it is activated and converted into atomic nitrogen and oxidized by atmospheric oxygen to nitrogen oxides which are then quenched in a reducing environment. The known method has the largest number of matching features and for this reason is selected as a prototype.

EFFECT: reduced toxic emissions and increased stability of the process of burning solid pulverized fuel.

, путем подачи лазерного излучения в цилиндрическую камеру подготовки воздуха с зеркальной поверхностью, по меньшей мере, в одном месте под углом к ее поверхности, меньшим угла полного отражения от зеркальной поверхности цилиндрической камеры подготовки воздуха по винтообразной ломаной кривой с шагом между соседними витками винтообразной ломаной линии, большим линейного габаритного размера (l), измеренного вдоль оси цилиндрической камеры подготовки воздуха, обработанную часть первого потока воздуха с синглетным кислородом подают через коаксиальную перфорированную перегородку в пристеночную область камеры горения, при этом увеличивают концентрацию синглетного кислорода по направлению к выходу из камеры горения.The technical result is achieved by the method of burning pulverized fuel, including the separation of air by adsorption of nitrogen on the zeolite, form the first air stream enriched with oxygen, and the second air stream enriched with nitrogen, extracted from the surface of the zeolite by heating it, then the second air stream is divided into main and additional streams, an additional stream is mixed with pulverized fuel, and the mixture is fed to the beginning of the ignition chamber, and part of the mixture of an additional stream of air and pulverized fuel and it is fed through a plasma torch to the ignition chamber, where a gasification torch of a part of pulverized fuel is formed under conditions of oxygen deficiency, a part is separated from the first air stream and fed to the ignition chamber through an exit section of the plasmatron through an air exhaust pipe, an ignition torch is formed of a part of the dusty gasified in the plasmatron fuel, which ignites a mixture of an additional stream of air and pulverized fuel, the combustion products from the ignition chamber are mixed with the main stream of air and at the oxygen stream is fed into the combustion chamber, the remaining part of the first stream enriched with oxygen is fed into the air preparation chamber, where it is treated with laser radiation from a solid-state laser with a wavelength of 762 ± 0.5 and / or 1268 ± 0.5 nm, which causes the transition of oxygen molecules from the ground electronic state to an excited singlet state $$O_2(b^{\mathrm{one}}{\displaystyle {\sum }_g^{+})}$$

by supplying laser radiation into a cylindrical chamber for preparing air with a mirror surface at least in one place at an angle to its surface less than the angle of total reflection from the mirror surface of a cylindrical chamber for preparing air along a helical broken line with a step between adjacent turns of a helical broken line large linear dimension (l), measured along the axis of the cylindrical chamber of the air preparation, the treated part of the first air flow with singlet oxygen is fed through a coaxial perforated septum into the wall region of the combustion chamber, while increasing the concentration of singlet oxygen towards the exit of the combustion chamber.

In the ignition chamber, immediately after the plasma torch, the products of gasification of pulverized fuel and individual atoms of highly active atomic nitrogen, mix with the rest of the stream carrying pulverized fuel, cool and, due to lack of oxygen, interact with hydrogen and other products of gasification of pulverized fuel and among themselves, forming, for example, ammonia and molecular nitrogen. At the end of the ignition chamber, gasification products and ammonia are burned in a flare enriched with oxygen, which will contribute to the stable burning of the flare in the ignition chamber. The main part of the second air stream and most of the pulverized fuel are under conditions of oxygen deficiency, but under the influence of a stable flame in the ignition chamber it ignites, burns and partially gasifies. A vortex is formed on the ledge of the combustion chamber, which returns the gasification products to the root zone of the dust-like fuel flame, which increases the stability of this combustion flame.

Due to the small losses of the laser beam due to reflection in the air preparation chamber, the mirror surface of the chamber almost does not heat up and does not collapse. Small in amplitude oscillations of the mirror walls slightly change the trajectory of movement and reflection of the laser beam along a broken helical curve. This leads to an increase in the irradiated volume of the first air stream and changes the position of the spots of reflection of the laser beam on the mirror surface of the preparation chamber and, accordingly, reduces the heating of its individual local sections. In this case, during the movement of the first stream of oxygen-enriched air through the air treatment chamber, the proportion of singlet oxygen increases, and therefore, its intake into the combustion chamber increases, which leads to an increase in the efficiency of the chain reactions of additional oxidation of CO, nitrogen and sulfur oxides, soot, etc. P.

In FIG. 1 schematically shows a device for the preparation of air and pulverized fuel with a chamber for burning it and with a device for introducing a laser beam into the chamber for preparing air with the proposed projection of a helical broken line obtained by its multiple reflection, which allows to implement the proposed method.

In FIG. Figure 2 shows a cross section of the combustion chamber at the location of the device for introducing a laser beam into the air preparation chamber with a projection of a helical broken line obtained by its multiple reflection.

A device for implementing the method of burning pulverized fuel contains a schematically shown air compression device 1, an air preparation device 2 with an air preparation chamber 3, a plasma-chemical processing device for pulverized fuel 4, including a plasmatron 5, and a combustion chamber 6, as well as pipelines connecting them. The air preparation device 2 is equipped with an air separation device 7 with the possibility of air separation according to the main components on the zeolite filler, made with the possibility of periodic heating of the zeolite, with one inlet pipe 8 and the first 9 and second 10 output pipes, respectively, 9 for the first air stream with increased the oxygen content and 10 for the second air stream with a high nitrogen content, the second output pipe 10 is in communication with the pipe 11 for supplying pulverized fuel and the camera 12 zazhi gania, in which the device 4 for plasma-chemical processing of pulverized fuel, made annular, and communicated with the first outlet pipe through the pipe 13 of the selection of air with a high oxygen content located in the ignition chamber in the inner part of the ring device 4 of the plasma-chemical processing of pulverized fuel, the output section of the pipe 13 the air intake protrudes beyond the exit section of the plasma torch 5, the inner surface 15 of the chamber 3 for air preparation is made mirror, and the device 2 The air is made in the form of a solid-state laser 16 with a wavelength of 762 ± 0.5 and / or 1268 ± 0.5 nm, the output 17 of which, for example, made in the form of a translucent focusing mirror or fiber, etc., is directed at an angle to the mirror the surface of the air preparation chamber, smaller than the angle of total reflection from the mirror surface 15 of the air preparation chamber 3, with the possibility of the laser beam 16 forming at least a single helical broken line 18, step 19 of which between adjacent turns is larger than the linear overall dimension (l) out one window 20 in the mirror surface 15 to accommodate the output 17 of the solid-state laser 16, the air preparation chamber 3 is in communication with the combustion chamber 6 through a perforated partition 21 located coaxially to the mirror surface 15 and having a variable perforation ratio, i.e. the ratio of the area of the holes 22 of the partition (shown conventionally ) to the total area of the partition 21, respectively, less in the afterburning area of the mixture 23 and more in the dilution zone 24 of the products of incomplete combustion of the mixture with oxygen in its singlet state. The perforation holes 22 can have various shapes, for example, in the form of punches with a semicircular cross section, directed by the open part in the direction of flow of the working fluid, which protects the air preparation chamber from the ingress of solid particles of slag as a visor from rain, similar forms are widely used in chambers combustion and flame tubes and prevent particles of slag or other solid particles from entering the air preparation chamber 3. The lower part of the combustion chamber 6 has a slag collector 25.

The operation of the device for burning pulverized fuel is as follows.

Air from the atmosphere enters the air compression device 1, for example, a centrifugal compressor, and under pressure is sent to the air preparation device 2, where it is separated by adsorption on the zeolite, the first oxygen-enriched air stream is formed, and it is sent to the first pipe 9 for the first stream air, and the second air stream enriched with nitrogen is sent to the second pipe 10 for the second air stream. The second air stream is divided into primary and secondary flows. The additional stream is sent to the pulverized fuel supply pipe 11, in which the additional stream of nitrogen enriched air is mixed with the pulverized fuel, and directed to the plasma chemical processing device 4 of the pulverized fuel. Part of the mixture of suspended in the air pulverized fuel and an additional stream of air is fed to the inlet of the plasma torch 5, where the mixture is processed by low-temperature plasma, solid particles of pulverized fuel are gasified, oxygen and nitrogen in the air are ionized. When moving along the plasma-chemical fuel treatment device 4 (with a lack of an oxidizing agent, i.e. oxygen), atomic nitrogen of air, sulfur, nitrogen compounds and hydrogen from gasified pulverized fuel combine to form ammonia, sulfur compounds and other products of gasification and incomplete combustion of pulverized fuel. With further movement along the ignition chamber 12, these products are mixed with the third air stream coming from the air sampling pipe 13, the output cut of which is located behind the output cut of the plasma torch 5. After the plasma torch, the mixture ignites in the ignition chamber 12, and all components activated by ionization are stably burning such as soot, ammonia or carbon monoxide, which form an ignition torch that ignites the mixture of additional air flow with pulverized fuel remaining in the pipe 11, which, by mixing s with the main stream, burning in the conditions of oxygen deficiency and enters the combustion chamber 6. The combustion temperature cannot be very high, at which nitrogen oxides can be re-formed. On the ledge immediately at the exit of the second stream to the combustion chamber 6, a stable vortex is formed, and with its help, the burning products of incomplete combustion are returned and sucked into the root of the combustion torch of the flow of pulverized fuel mixed with air, which should stabilize its combustion.

In this case, the remainder of the first oxygen-enriched air stream is supplied from the pipeline 9 to the air preparation chamber 3, where it is treated with a laser to obtain its singlet state, since the inner surface 15 of the air preparation chamber 3 is mirrored, and the air preparation device 2 is made in in the form of a solid-state laser 16 with a wavelength of 762 ± 0.5 and / or 1268 ± 0.5 nm, the output 17 of which, for example, made in the form of a translucent focusing mirror or fiber, etc., is directed at an angle to the mirror the surface of the chamber 3 of the air preparation, smaller than the angle of total reflection from the mirror surface 15 of the chamber 3 of the air preparation, with the possibility of the formation of the laser beam 16, at least a single-helical broken line 18, the step 19 of which between adjacent turns is larger than the linear overall dimension l of the exit window 20 located on the mirror surface of the camera 3, the output 17 of the solid-state laser 16, i.e. the linear size of the device to accommodate the output 17 of the solid-state laser 16 on the mirror wall, measured along the axis of the chamber 3 of the air preparation. Multiple reflection of the laser beam from the mirror surface occurs without loss and cannot damage the mirror surface. It should be noted that the laser beam has finite dimensions and when reflected from a curved surface, it will defocus and increase the volume of irradiated air and the mass of the singlet state of oxygen in it will increase, this will be facilitated by an increased percentage of oxygen in the stream. Further, the air enriched in singlet oxygen is supplied to the wall region of the combustion chamber through a perforated wall, and it oxidizes incomplete combustion products, such as soot, carbon monoxide (carbon monoxide), nitrogen and sulfur oxides. Oxygen in its singlet state initiates, according to the chain reaction scheme, the oxidation of these products of incomplete combustion to carbon dioxide or molecular nitrogen. Along the length of the chamber 3 air preparation, the concentration of singlet oxygen increases, which increases the intensity of the process of oxidation of the above products of incomplete combustion of pulverized fuel. Mineral non-combustible substances that form the basis of slag fall out of the stream and enter the slag collector.

The heat generated can be used by known methods using known means.

Claims (1)

A method of burning pulverized fuel, including the separation of air by adsorption of nitrogen on zeolite, while
form the first stream of air enriched with oxygen, and
a second air stream enriched with nitrogen released from the surface of the zeolite by its heating method,
then the second air stream is divided into primary and secondary flows,
the additional stream is mixed with pulverized fuel and the mixture is fed to the beginning of the ignition chamber,
moreover, part of the mixture of an additional stream of air and pulverized fuel is fed through a plasma torch to the ignition chamber, where a gasification torch is formed for part of the pulverized fuel in the absence of oxygen,
a part is separated from the first air stream, and by means of an air sampling pipe, it is supplied to the ignition chamber for the output section of the plasma torch,
after the plasma torch, an ignition torch is formed for a part of the gasified dust-like fuel in the plasma torch, which ignites a mixture of an additional stream of air and dust-like fuel,
combustion products from the ignition chamber are mixed with the main air stream and, with a lack of oxygen, are fed into the combustion chamber,
the remaining part of the first stream, enriched with oxygen, is fed into the air preparation chamber, where it is treated with laser radiation from a solid-state laser with a wavelength of 762 ± 0.5 and / or 1268 ± 0.5 nm, which causes the transition of oxygen molecules from the ground electronic state to the excited singlet state state $$O_2(b^{\mathrm{one}}{\displaystyle {\sum }_g^{+})}$$

by supplying laser radiation into a cylindrical chamber for preparing air with a mirror surface at least in one place at an angle to its surface less than the angle of total reflection from the mirror surface of a cylindrical chamber for preparing air along a helical broken line with a step between adjacent turns of a helical broken line large linear dimension l, measured along the axis of the cylindrical chamber of the air preparation,
the treated portion of the first air flow with singlet oxygen is fed through a coaxial perforated septum into the wall region of the combustion chamber, while the concentration of singlet oxygen is increased towards the exit of the combustion chamber.

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