CN108194919B - Boiler fire coal pretreatment device, boiler fire coal pretreatment method and boiler - Google Patents
Boiler fire coal pretreatment device, boiler fire coal pretreatment method and boiler Download PDFInfo
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- CN108194919B CN108194919B CN201810295784.3A CN201810295784A CN108194919B CN 108194919 B CN108194919 B CN 108194919B CN 201810295784 A CN201810295784 A CN 201810295784A CN 108194919 B CN108194919 B CN 108194919B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C6/00—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion
- F23C6/04—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection
- F23C6/042—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection with fuel supply in stages
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K3/00—Feeding or distributing of lump or pulverulent fuel to combustion apparatus
- F23K3/02—Pneumatic feeding arrangements, i.e. by air blast
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C2201/00—Staged combustion
- F23C2201/30—Staged fuel supply
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Abstract
The invention discloses a boiler fire coal pretreatment device, a boiler fire coal pretreatment method and a boiler. The boiler fire coal pretreatment device comprises: the air inlet pipe is used for receiving and outputting the wind-powder mixture; the main reaction chamber is connected with the air inlet pipe and is used for enabling the pulverized coal to carry out pyrolysis and gasification reactions and outputting products after the pyrolysis and gasification reactions; the ignition source of the heat source is arranged in the boiler coal pretreatment device and is used for igniting the wind-powder mixture; the powder distribution pipe system comprises a first pipe system, wherein the first pipe system is provided with a first pipe system output port communicated with the main reaction chamber, and the first pipe system output port is positioned at the downstream of the heat source in the main flow direction of the gas-solid mixture of the boiler coal pretreatment device and is used for introducing a first pulverized coal airflow with the concentration higher than that of the wind-powder mixture into a main reaction area in the main reaction chamber. The device is beneficial to generating a great amount of reducing gas and realizing low NO x And (5) discharging.
Description
Technical Field
The invention relates to the field of combustion equipment, in particular to a boiler fire coal pretreatment device, a boiler fire coal pretreatment method and a boiler.
Background
According to the requirements of 'fully implementing ultralow emission and energy-saving transformation working scheme' of coal-fired power plants, all national coal-fired power plants with conditions need to realize ultralow emission in 2020, wherein the emission concentration of oxynitride is not higher than 50mg/m 3 . At present, most of domestic power plants adopt tail SCR (Selective Catalytic Reduction ) denitration technology, huge SCR denitration operation and maintenance cost is paid every year, and the overall economic benefit is poor. Meanwhile, the SCR denitration system is easy to cause corrosion and blockage of a downstream air preheater, and the safety of a boiler unit is affected. In addition, secondary pollution caused by SCR catalyst and ammonia slip cannot be effectively solved. Thus, there is a need for in-furnace low nitrogen combustion technology that enables ultra-low emissions.
The currently widely accepted low nitrogen combustion technology route in the furnace is to inject reducing gas into the furnace to reduce the generated NOx into N 2 Realizing ultra-low emission of NOx. The natural gas is used as the reducing gas to reburning energy to effectively reduce the concentration of NOx, and the emission reduction rate can reach 70 percent, but the operation cost is too high, and the popularization is difficult.
Disclosure of Invention
The invention aims to provide a boiler coal pretreatment device and a boiler coal pretreatment method, and a large amount of reducing gas can be obtained by utilizing the device or the method to pretreat boiler coal so as to help realize low NOx and ultralow emission of the boiler. The boiler fire coal pretreatment device has simple structure, low cost and easy popularization. Meanwhile, the utility model also discloses a boiler with the boiler fire coal pretreatment device.
The first aspect of the invention discloses a boiler fire coal pretreatment device, comprising:
the air inlet pipe is used for receiving and outputting the wind-powder mixture;
the main reaction chamber is connected with the air inlet pipe and is used for enabling the pulverized coal to carry out pyrolysis and gasification reactions and outputting products after the pyrolysis and gasification reactions;
the ignition source of the heat source is arranged in the boiler coal pretreatment device and is used for igniting the wind-powder mixture;
the powder distribution pipe system comprises a first pipe system, wherein the first pipe system is provided with a first pipe system output port communicated with the main reaction chamber, and the first pipe system output port is positioned at the downstream of the heat source in the main flow direction of the gas-solid mixture in the boiler coal pretreatment device and is used for introducing a first coal powder gas flow with the concentration higher than that of the wind-powder mixture into a main reaction area in the main reaction chamber.
Further, the first tubing output port comprises at least two first tubing sub-output ports sequentially arranged in the main flow direction of the gas-solid mixture, and the at least two first tubing sub-output ports are used for carrying the first pulverized coal gas flow in a graded manner to the main reaction area.
Further, the powder distribution pipe system further comprises a second pipe system, the second pipe system is provided with a second pipe system output port communicated with the boiler fire coal pretreatment device, and the second pipe system output port is used for introducing a second coal dust air flow into an ignition area for igniting the wind-powder mixture by the heat source.
Further, the powder distribution pipe system further comprises a powder distribution main pipe, the first pipe system and the second pipe system are connected with an output port of the powder distribution main pipe, and the coal powder airflow output from the powder distribution main pipe is optionally led into the boiler coal burning pretreatment device from the first pipe system and/or the second pipe system.
Further, the powder distribution pipe system further includes a flow distribution device that adjustably distributes the pulverized coal flow output from the powder distribution header pipe to the first pipe system and the second pipe system at different flows.
Further, the main reaction chamber comprises a main pipe section, wherein,
the cross section area of the main pipe section is 3-15.5 times of the cross section area of the air inlet pipe; and/or the number of the groups of groups,
the included angle between the main pipe section and the vertical direction is 0-30 degrees.
Further, the boiler fire coal pretreatment device further comprises an output pipe, the output pipe is connected with the main reaction chamber and used for outputting products after pyrolysis and gasification reaction to a hearth of the boiler body, the main reaction chamber comprises a main pipe section, and the cross section area of the output pipe is smaller than that of the main pipe section.
Further, the main reaction chamber further comprises a deceleration section connected with the air inlet pipe and the main pipe section, and the deceleration section is arranged at the downstream of the air inlet pipe in a gradually expanding manner along the main flow direction of the gas-solid mixture; and/or the number of the groups of groups,
the main reaction chamber further comprises an accelerating section connected with the main pipe section and the output pipe, and the accelerating section is gradually arranged at the downstream of the main pipe section along the main flow direction of the gas-solid mixture.
Further, the accelerating section and the main pipe section are coaxially arranged; and/or the number of the groups of groups,
the deceleration section is coaxially arranged with the main pipe section.
Further, the air inlet pipe further comprises a bent pipe section, and the heat source is positioned at the downstream of the outlet of the bent pipe section along the main flow direction of the gas-solid mixture.
The second aspect of the invention discloses a boiler fire coal pretreatment method, comprising the following steps:
introducing an air-powder mixture into the boiler coal pretreatment device;
igniting the air-powder mixture with a heat source;
introducing a first pulverized coal airflow, and introducing the first pulverized coal airflow with the concentration higher than that of the air-powder mixture into a main reaction area positioned at the downstream of an ignition source of the heat source in the main flow direction of a gas-solid mixture of the boiler coal pretreatment device, wherein the pulverized coal is subjected to pyrolysis and gasification reaction in the main reaction chamber of the boiler coal pretreatment device;
outputting the products after pyrolysis and gasification reaction.
Further, the first pulverized coal airflow comprises pulverized coal and conveying gas, and the conveying gas is air or inert gas.
Further, the conveying gas is air, and the mass ratio of pulverized coal to air in the pulverized coal airflow is more than 20.
Further, the introducing the first pulverized coal stream includes introducing the first pulverized coal stream in at least two stages in a main flow direction of the gas-solid mixture.
Further, the boiler coal pretreatment method further comprises the step of introducing a second pulverized coal airflow into an ignition area where the heat source of the boiler coal pretreatment device ignites the air-powder mixture.
Further, the boiler coal pretreatment method comprises switchably introducing the first pulverized coal airflow into the main reaction area and/or introducing the second pulverized coal airflow into the ignition area.
Further, the boiler coal pretreatment method includes adjustably introducing the first and second pulverized coal streams at different flow rates to the main reaction zone and the ignition zone.
The third aspect of the invention discloses a boiler, which comprises a boiler body and a boiler coal pretreatment device, wherein the boiler coal pretreatment device is the boiler coal pretreatment device in the first aspect of the invention, and the main reaction chamber is connected with a hearth of the boiler body so as to introduce the pyrolysis and gasification reaction products into the hearth.
According to the boiler coal pretreatment device and the boiler coal pretreatment method provided by the invention, firstly, the air-powder mixture with lower coal powder concentration is introduced into the boiler coal pretreatment device, the air-powder mixture has larger excess air coefficient when in coal powder combustion, and the air-powder mixture ignited by a heat source can be combusted more uniformly and is easier to combust to fully generate a high-temperature environment; then, a first coal dust air flow with higher concentration is introduced into a main reaction area of the pyrolysis and gasification reaction of the main reaction chamber to carry out the pyrolysis and gasification reaction, and a reducing atmosphere can be effectively formed in the device, so that a large amount of reducing gas can be generated. By using the boiler coal pretreatment device and the boiler coal pretreatment method, the coal quality requirement can be reduced and the gas yield of the reducing gas can be improved by dividing the coal dust gas flow into the wind-powder mixture with lower concentration and the first coal dust gas flow with higher concentration. Compared with the prior art, the device is beneficial to avoiding the problems that the conventional coal gasification device is usually used for injecting pulverized coal, gasifying agent and oxidant into the device at one time, local oxidant is excessive, so that the combustion of air flow is uneven, or excessive pulverized coal is consumed for combustion when the combustion effect is ensured and the oxidant is excessive, the temperature is too high, and the wall temperature of the device is easy to cause over-temperature coking and the like; meanwhile, the method is favorable for avoiding the problems that the existing consumption generates more reducing gas, the reducing atmosphere is difficult to form in the device, the gas yield is low, the requirement on the coal quality is high and the like.
Based on the boiler provided by the invention, the requirements on the quality of the fire coal of the boiler can be reduced, the quantity of the introduced reducing gas into the hearth is large, and the low NO is realized x And the emission and the like.
Other features of the present invention and its advantages will become apparent from the following detailed description of exemplary embodiments of the invention, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:
FIG. 1 is a schematic diagram of a boiler coal pretreatment apparatus according to an embodiment of the present invention;
fig. 2 is a schematic structural view of a boiler fire coal pretreatment device according to another embodiment.
Detailed Description
Technical aspects of embodiments of the present invention will be clearly and fully described in the following description of the embodiments of the present invention with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some, but not all embodiments of the present invention. The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless it is specifically stated otherwise. Also, it should be understood that the dimensions of the various parts shown in the figures are not drawn to actual scale for ease of description. Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the specification where appropriate. In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.
Spatially relative terms, such as "above … …," "above … …," "upper surface at … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial location relative to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or structures would then be oriented "below" or "beneath" the other devices or structures. Thus, the exemplary term "above … …" may include both orientations of "above … …" and "below … …". The device may also be positioned in other different ways (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Fig. 1 is a schematic structural view of a boiler fire coal pretreatment device according to an embodiment of the present invention. As shown in fig. 1, the boiler fire coal pretreatment device in this embodiment comprises an air inlet pipe 1, a main reaction chamber 3, a heat source 2 and a powder distribution pipe system.
The air inlet pipe 1 comprises an air inlet pipe input port and an air inlet pipe output port and is used for inputting and outputting air-powder mixture. An ignition source 21 of the heat source 2 is arranged in the boiler fire coal pretreatment device and is used for igniting the wind-powder mixture. The main reaction chamber 3 is communicated with the air inlet pipe 1 and is used for carrying out pyrolysis and gasification reactions on the coal dust and outputting products. The main reaction chamber 3 comprises a main reaction chamber input port and a main reaction chamber output port, and the main reaction chamber input port is connected with the air inlet pipe output port. The powder distribution pipe system comprises a first pipe system, wherein the first pipe system is communicated with the main reaction chamber 3, the output port of the first pipe system is positioned at the downstream of the heat source 2 along the main flow direction of the gas-solid mixture of the boiler coal pretreatment device, and is used for introducing a first pulverized coal airflow with the concentration higher than that of the wind-powder mixture into the main reaction area of the main reaction chamber 3 for pyrolysis and gasification reaction. In the embodiment shown in fig. 1, the first tubing includes a first powder dispensing tube 91.
The heat source 2 provides a stable and reliable fire source for pyrolysis and gasification of the pulverized coal, and improves the adaptability of the pulverized coal gasification device to different working conditions and coal types. The ignition source of the heat source 2 may be disposed in the air inlet pipe so that the pulverized coal enters the main reaction chamber 3 after being ignited in advance. In some embodiments, an ignition source of the heat source 2 may also be disposed in the main reaction chamber 3, so that the pulverized coal is combusted in the main reaction chamber and then subjected to subsequent pyrolysis and gasification reactions. The ignition source may be a burner, a plasma device, an oil gun device, an air gun device, a high-temperature air supply device, or the like, which can ignite primary air powder.
The ignition source of the heat source 2 is taken as the center, the local area nearby is taken as the ignition area, and the wind-powder mixture is mainly ignited and burned by the heat source 2 in the ignition area. When the ignition source of the heat source 2 is arranged in the air inlet pipe 1, the ignition area is positioned in the air inlet pipe 1, and when the pulverized coal airflow is introduced into the main reaction chamber 3, the pulverized coal airflow mainly generates pyrolysis and gasification reactions in the main reaction chamber 3 to generate reducing gas, and at the moment, the areas in the main reaction chamber 3 are all main reaction areas of the pyrolysis and gasification reactions. When the heat source 2 is disposed within the main reaction chamber 3, the ignition region is located within the main reaction chamber 3 in the vicinity of the heat source 2. At this time, the downstream portion of the main reaction chamber 3 in the flow direction of the air-powder mixture in the ignition region is the main reaction region of the pyrolysis and gasification reaction of the main reaction chamber 3.
The air-powder mixture is a mixed air flow of coal powder and gas containing oxidant, such as mixed air flow of coal powder and air or oxygen-enriched air, and the air-powder mixture is a gas-solid mixture, as shown in the figure, is introduced from an inlet of an air inlet pipe along the x direction, and is ignited by a heat source 2. After the air-powder mixture is combusted, high temperature is generated for pyrolysis and gasification of the pulverized coal, and the pulverized coal can undergo pyrolysis and gasification in a high-temperature environment generated by the combustion of the air-powder mixture.
The main flow direction of the gas-solid mixture is the flow direction of the gas-solid mixture entering from the air inlet pipe 1 from the beginning to the last output in the whole process that the air-powder mixture flows along the boiler coal pretreatment device after entering the air inlet pipe 1, is ignited and burnt in the middle, and then carries the first coal powder airflow and/or the second coal powder airflow carried in and the pyrolysis and gasification reaction products to flow until the boiler coal pretreatment device is output.
The first pulverized coal stream may be conveyed by a conveying gas such as air, or by an inert gas such as nitrogen. When the air is used for conveying, the high-concentration pulverized coal airflow with the mass ratio of the pulverized coal to the air of more than 20-100 can be conveyed by conveying modes such as high-concentration powder pneumatic conveying, pulverized coal upper discharging type conveying tank pneumatic conveying and the like.
In the embodiment, the pulverized coal airflow is divided into the wind-powder mixture with lower concentration and the first pulverized coal airflow with higher concentration for conveying, so that the requirement on the quality of coal can be reduced, and the gas yield of the reducing gas can be improved. When the wind powder mixture with lower concentration is burnt, the air excess coefficient is larger, and the wind powder mixture ignited by the heat source 2 can be burnt more uniformly and is easier to burn to fully generate a high-temperature environment. Compared with the prior art, the device is beneficial to avoiding uneven combustion of wind powder air flow caused by excessive local oxidant when the conventional coal gasification device sprays coal dust, gasifying agent and oxidizing agent into the device at one time. The device can also help to avoid the problems that in order to ensure the combustion effect, excessive coal dust is consumed by combustion when excessive oxidant is introduced, the temperature is too high, the wall temperature of the device is easy to coke due to the excessive temperature, the consumption of reducing gas is more, the reducing atmosphere is difficult to form in the device, the gas production rate is low, the requirement on coal quality is high and the like in the prior art. The boiler coal pretreatment device of the embodiment has a simple structure and is easy to operate, the coal dust is pretreated by the boiler coal pretreatment device of the embodiment, the gasification treatment of the coal can be realized with low cost and low energy consumption, a large amount of reducing gas is safely and stably generated, and the ultralow emission of boiler NOx is facilitated.
In some embodiments, the first piping is fed into the main reaction chamber 3 with a pulverized coal-to-air mass ratio of pulverized coal airflow of greater than 20. Ideally, at least 7kg of air is required to achieve adequate combustion of 1kg of coal fines, i.e. the coal fines to air mass ratio is less than 0.14. When the first pipe system 91 introduces the first pulverized coal airflow with the high concentration, the mass ratio of the pulverized coal to the air of which is greater than 20, into the main reaction area of the pyrolysis and gasification reaction of the main reaction chamber 3, the content of the oxidant in the air for conveying the first pulverized coal airflow into the main reaction chamber 3 is low and can be ignored. The pulverized coal airflow can be regarded as high-concentration pulverized coal airflow, is more conducive to the stable pyrolysis and gasification reactions in the device, and is more conducive to effectively forming a reducing atmosphere, thereby being capable of generating a large amount of CH 4 、H 2 Reducing gases such as CO.
In some embodiments, the first piping may further be provided with a plurality of powder distribution pipes along the main flow direction of the gas-solid mixture for classifying and conveying the pulverized coal gas flow to the main reaction area where the pyrolysis and gasification reactions are performed. For example, as shown in fig. 2, the first piping includes a first powder dispensing pipe 91 and a second powder dispensing pipe 92. The output port of the first powder distribution pipe 91 and the output port of the second powder distribution pipe 92 form two first pipe train sub-output ports of the first pipe train, respectively. The output port of the first powder distribution pipe 91 and the output port of the second powder distribution pipe 92 are sequentially arranged in the main flow direction of the gas-solid mixture. A plurality of first tubing sub-outlets of the first tubing 91 are used to stage the first pulverized coal stream to the main reaction zone. The powder distribution pipes are arranged along the main flow direction of the gas-solid mixture, so that the first pulverized coal airflow is more uniformly distributed in the pyrolysis and gasification reaction area in the main reaction chamber 3, and the rapid pyrolysis and gasification reaction is facilitated.
In an embodiment not shown, the first piping may include only one powder dispensing tube, or more than three powder dispensing tubes. One powder distribution pipe can be arranged on the same section in the main flow direction of the gas-solid mixture, and more than two powder distribution pipes can be arranged.
In some embodiments, the pulverized coal distribution piping further comprises a second piping having a second piping output in communication with the boiler coal pretreatment device for delivering a second pulverized coal stream to the ignition region of the heat source 2. The second pipe system is arranged to convey the second pulverized coal airflow to the ignition area, so that the concentration of the air-powder mixture in the ignition area can be adjusted, and the combustion reaction can be adjusted, thereby adjusting the temperature in the main reaction chamber 3. In the embodiment shown in fig. 2, the second piping includes a third powder dispensing pipe 93.
In some embodiments, as shown in fig. 2, the powder distribution pipe system further comprises a powder distribution main pipe, the first pipe system and the second pipe system are connected with an output port of the powder distribution main pipe, and the pulverized coal airflow passing through the powder distribution main pipe along the y direction is selectively output from the first pipe system and/or the second pipe system. The pulverized coal gas stream can be selectively output from the first piping and/or the second piping by providing valves in the first piping and the second piping, respectively. The powder distribution main pipe is arranged, so that the pulverized coal airflow is led in more conveniently and flexibly, the integration level of the device is improved, and the device is simpler in structure and more convenient to operate.
In some embodiments, the boiler coal pretreatment device further comprises a flow distribution device, such as a throttle valve at the output of the powder distribution main pipe and the first and second pipe systems. The flow distribution device can distribute and lead the pulverized coal airflow output from the output port of the powder distribution main pipe into the first pipe system and the second pipe system in different proportions. By arranging the flow distribution device, the flow of the coal powder airflow introduced into the ignition area and the main reaction area in the boiler coal pretreatment device can be adjusted more easily and more flexibly.
In some embodiments, the main reaction chamber 3 comprises a main pipe section 33, the cross-sectional area of the main pipe section 33 of the main reaction chamber 3 being larger than the cross-sectional area of the air inlet pipe 1. This arrangement allows the flow rate of the air flow to be reduced when the air-powder mixture enters the main pipe section 33 of the main reaction chamber 3 from the air inlet pipe 1. When the heat source 2 is arranged in the air inlet pipe 1, the air-powder mixture is firstly ignited in the air inlet pipe 1, then the flow speed is reduced when the product air flow enters the main reaction chamber 3, the residence time in the main reaction chamber 3 is prolonged, the residence time of the first coal powder air flow which is introduced into the main reaction chamber 3 by the first pipe system and flows in the main pipe section 33 of the main reaction chamber 3 under the action of the product air flow is prolonged, and the pyrolysis and gasification reaction time of the first coal powder air flow in the main pipe section 33 of the main reaction chamber 3 is prolonged, so that the generation of reducing gas is facilitated. When the heat source 2 is disposed at the upper end of the main reaction chamber 3, the flow rate of the air-powder mixture entering the main pipe section 33 from the air inlet pipe is reduced, and besides the pyrolysis and gasification reaction time of the first pulverized coal is prolonged, the time passing through the heat source 2 is prolonged, and the mixture is more easily ignited and burned by the heat source 2.
In some embodiments, the cross-sectional area of the main pipe section 33 of the main reaction chamber 3 is 3 to 15.5 times the cross-sectional area of the air inlet pipe 1. When the ratio of the cross-sectional area of the main pipe section 33 to the cross-sectional area of the air inlet pipe 1 is in the range of 3-15.5, the length and the transverse dimension of the main pipe section 33 can be set to be reasonable while the pyrolysis and gasification reactions of the pulverized coal are met to generate enough reducing gas, and the whole installation of the boiler coal pretreatment device is convenient in the limited structural space range of the pulverized coal boiler, and the cost of the boiler coal pretreatment device is reasonable due to the reasonable length and transverse dimension; moreover, the boiler fire coal pretreatment device has proper structural space, proper coal powder airflow speed in the main reaction chamber and less phenomena of powder accumulation and slag bonding.
In some embodiments, the boiler coal pretreatment device further comprises an output pipe 5, the output pipe 5 comprising an output pipe input port and an output pipe output port 6. The output pipe input port is connected with the output port of the main reaction chamber and is used for outputting products after pyrolysis and gasification reaction to the hearth of the boiler body 4 through the output pipe output port 6.
The outlet pipe 5 has a cross-sectional area smaller than the cross-sectional area of the main pipe section 33 of the main reaction chamber 3. The cross section area of the output pipe 5 is smaller than that of the main pipe section 33, and the flow speed of the product gas flow after the pyrolysis and gasification reaction entering the output pipe 5 from the main reaction chamber 3 is improved, so that the phenomena of powder accumulation and slag bonding of the pipeline of the boiler coal pretreatment device are reduced.
In some embodiments the main reaction chamber 3 further comprises an acceleration section 32. The outlet pipe 5 may be connected directly to the main reaction chamber 3 or, as shown in fig. 1, may be connected to the main reaction chamber 3 via an acceleration section 32. The acceleration section 32 includes an acceleration section input port and an acceleration section output port having a smaller cross-sectional area than the acceleration section input port, the acceleration section output port being connected to the output pipe input port. By adding the acceleration section 32, the gas flow rate lifting process is smoother, helping to avoid vortex generation and reduce resistance to gas flow.
In some embodiments, the main pipe section 33 of the main reaction chamber 3 is inclined at an angle of 0-30 ° to the vertical, preferably arranged in the vertical direction. When the included angle between the main pipe section 33 and the vertical direction is 0-30 degrees, the pulverized coal combustion is more stable, and meanwhile, the temperature distribution on the cross section perpendicular to the main flow direction of the gas-solid mixture in the main reaction chamber 3 is uniform, so that the uniform high-temperature environment is formed in the main reaction chamber 3, and the pyrolysis and gasification reaction of the pulverized coal are promoted. At the same time, the arrangement of the main pipe section 33 is beneficial to further reducing the powder accumulation and slag bonding of the pipeline in the boiler coal pretreatment device under the action of gravity.
In some embodiments, as shown in fig. 2, the air inlet pipe 1 further includes a bend section 7, and the ignition source 21 of the heat source 2 is located downstream of the outlet of the bend section in the main flow direction of the gas-solid mixture. When passing through the bent pipe section 7, the air-powder mixture introduced into the air inlet pipe 1 can gather at the outer arc side of the outlet of the bent pipe section 7 due to the action of centrifugal force, so that the concentration of coal powder in the coal powder airflow at the outer arc side is improved, and a concentration effect is formed.
In some embodiments, the power of the heat source 2 is adjustable. By adjusting the power of the heat source 2, the ignition intensity of the ignition source 21 for igniting the air-powder mixture can be adjusted, so that the combustion intensity in the coal powder pretreatment device can be controlled, the working temperature of the boiler coal pretreatment device can be adjusted, and the device overtemperature and slagging can be prevented.
In some embodiments, the bend section 7 further includes a baffle positioned within the bend section 7 and disposed between the inner and outer arcuate sides of the bend section 7. The deflector is used to deflect the incoming air-powder mixture downstream of the bend section 7. After the bend section 7 is provided with the guide plate, the air flow passing through the bend section 7 can better play a role in guiding, the aggregation effect of the bend section on the wind-powder mixture can be better exerted, the eddy flow generated when the wind-powder mixture is introduced is further reduced, and meanwhile, the concentration effect is further improved.
In some embodiments, as shown in fig. 2, the main reaction chamber 3 of the boiler coal pretreatment device further includes a deceleration section 31, and the deceleration section 31 includes a deceleration section input port and a deceleration section output port having a larger cross-sectional area than the deceleration section input port. The input port of the deceleration section is connected with the output port of the air inlet pipe, and the output port of the deceleration section is connected with the input port of the main pipe section 33. The provision of the deceleration section 31 is advantageous in addition to the smooth flow deceleration from the air inlet duct 1 to the main reaction chamber 3. Meanwhile, as shown in fig. 2, when the deceleration section 31 is connected with the bend section 2 of the air inlet pipe 1, it is helpful to eliminate the vortex at the initial stage of ignition, and is beneficial to the diffusion and combustion stability of the flame of the air-powder mixture.
The boiler coal pretreatment device of the above embodiment can reduce NOx generated when coal dust is combusted due to a large amount of reducing gas generated in the gasification process, so that the NOx in the outlet product of the coal dust pretreatment device can be 0 or tends to 0.
The invention also discloses a boiler coal pretreatment method, which comprises the following steps: introducing an air-powder mixture into a boiler coal pretreatment device; igniting the wind-powder mixture by using a heat source 2; introducing a first pulverized coal airflow with the concentration of pulverized coal higher than that of the air-powder mixture into a main reaction area of the boiler coal pretreatment device, which is positioned at the downstream of the heat source 2 along the main flow direction of the gas-solid mixture of the boiler coal pretreatment device and is used for pyrolysis and gasification reaction, wherein the pulverized coal reacts in the boiler coal pretreatment device; outputting pyrolysis and gasification products.
In some embodiments, the transport gas in the first pulverized coal stream is air or an inert gas.
In some embodiments, the first pulverized coal stream is conveyed by air, and the pulverized coal to air mass ratio in the first pulverized coal stream is greater than 20.
In some embodiments, the first pulverized coal stream is introduced at least two stages along the main flow direction of the gas-solid mixture.
In some embodiments, the boiler coal pretreatment method further comprises passing a second pulverized coal stream into an ignition region of the heat source 2 in the boiler coal pretreatment device.
In some embodiments, the boiler coal pretreatment method comprises switchably introducing a pulverized coal stream into a main reaction zone of a boiler coal pretreatment device where pyrolysis and gasification reactions are performed and/or an ignition zone of the heat source 2.
In some embodiments, a method of boiler coal pretreatment includes adjustably passing, by a flow distribution device, a first pulverized coal stream and a second pulverized coal stream at different flows to a main reaction zone and a heat source ignition zone in the boiler coal pretreatment device.
The embodiment of the invention also discloses a boiler using the boiler fire coal pretreatment device, and the boiler fire coal pretreatment device is connected with the hearth of the boiler body 4. The boiler of this embodiment has all the advantages of the boiler coal pretreatment device.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same; while the invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that: modifications may be made to the specific embodiments of the present invention or equivalents may be substituted for part of the technical features thereof; without departing from the spirit of the invention, it is intended to cover the scope of the invention as claimed.
Claims (19)
1. A boiler coal pretreatment device, comprising:
an air inlet pipe (1) for receiving and outputting an air-powder mixture;
the main reaction chamber (3) is connected with the air inlet pipe (1) and is used for enabling the pulverized coal to carry out pyrolysis and gasification reactions and outputting products after the pyrolysis and gasification reactions;
the ignition source (21) of the heat source (2) is arranged in the boiler coal pretreatment device and is used for igniting the wind-powder mixture;
the powder distribution pipe system comprises a first pipe system, wherein the first pipe system is provided with a first pipe system output port communicated with the main reaction chamber (3), and the first pipe system output port is positioned at the downstream of the heat source (2) in the main flow direction of the gas-solid mixture in the boiler coal pretreatment device and is used for introducing a first pulverized coal airflow with concentration higher than that of the air-powder mixture into a main reaction area in the main reaction chamber (3).
2. The boiler coal pretreatment apparatus of claim 1, wherein said first piping output comprises at least two first piping sub-outputs sequentially arranged in a main flow direction of said gas-solid mixture, said at least two first piping sub-outputs for staged delivery of said first pulverized coal stream to said main reaction zone.
3. The boiler coal pretreatment device of claim 1, wherein the pulverized coal distribution piping further comprises a second piping having a second piping output in communication with the boiler coal pretreatment device, the second piping output for passing a second pulverized coal stream into an ignition zone where the heat source ignites the pulverized wind mixture.
4. A boiler fire coal pretreatment device as claimed in claim 3, wherein said distribution piping further comprises a distribution header, said first piping and said second piping are connected to an output port of said distribution header, and a flow of pulverized coal outputted from said distribution header is selectively introduced into said boiler fire coal pretreatment device from said first piping and/or said second piping (93).
5. The boiler coal pretreatment device of claim 4, wherein said pulverized coal piping further comprises a flow distribution device, said flow distribution device adjustably distributing pulverized coal flow output from said pulverized coal distribution header pipe to said first piping and said second piping at different flows.
6. The boiler fire coal pretreatment device according to claim 1, wherein the main reaction chamber (3) comprises a main pipe section (33), wherein,
the cross section area of the main pipe section (33) is 3-15.5 times of the cross section area of the air inlet pipe (1); and/or the number of the groups of groups,
the included angle between the main pipe section (33) and the vertical direction is 0-30 degrees.
7. The boiler fire coal pretreatment device according to claim 1, further comprising an output pipe (5), said output pipe (5) being connected to said main reaction chamber (3) and being adapted to output said pyrolysis, gasification reaction products to the furnace of the boiler body (4), said main reaction chamber (3) comprising a main pipe section (33), wherein the cross-sectional area of said output pipe (5) is smaller than the cross-sectional area of said main pipe section (33).
8. The boiler fire coal pretreatment device according to claim 7,
the main reaction chamber (3) further comprises a deceleration section (31) connected with the air inlet pipe (1) and the main pipe section (33), and the deceleration section (31) is arranged at the downstream of the air inlet pipe (1) in a gradually expanding manner along the main flow direction of the gas-solid mixture; and/or the number of the groups of groups,
the main reaction chamber (3) further comprises an acceleration section (32) connecting the main pipe section (33) and the output pipe (5), and the acceleration section (32) is arranged downstream of the main pipe section (33) in a tapered manner along the main flow direction of the gas-solid mixture.
9. The boiler fire coal pretreatment device according to claim 8,
the accelerating section (32) is coaxially arranged with the main pipe section (33); and/or the number of the groups of groups,
the deceleration section (31) is arranged coaxially with the main pipe section (33).
10. The boiler fire coal pretreatment apparatus according to claim 1, wherein the air inlet pipe (1) further comprises a bend (7), and the heat source (2) is located downstream of the bend output in the main flow direction of the gas-solid mixture.
11. The boiler coal pretreatment apparatus of any of claims 1 to 10, wherein the power of the heat source is adjustable.
12. A method for pretreating coal for a boiler, comprising:
introducing an air-powder mixture into the boiler coal pretreatment device;
igniting the air-powder mixture with a heat source (2);
introducing a first pulverized coal airflow, and introducing the first pulverized coal airflow with the concentration higher than that of the air-powder mixture into a main reaction area positioned at the downstream of an ignition source of the heat source (2) in the main flow direction of a gas-solid mixture of the boiler coal pretreatment device, wherein the pulverized coal is subjected to pyrolysis and gasification reaction in the main reaction chamber of the boiler coal pretreatment device;
outputting the products after pyrolysis and gasification reaction.
13. The boiler coal pretreatment process of claim 12, wherein said first pulverized coal stream comprises pulverized coal and a conveying gas, said conveying gas being air or an inert gas.
14. The method for pretreating coal for a boiler of claim 13, wherein the conveying gas is air, and the mass ratio of pulverized coal to air in the pulverized coal stream is greater than 20.
15. The boiler coal pretreatment process of claim 12, wherein introducing a first pulverized coal stream comprises introducing the first pulverized coal stream in at least two stages in a main flow direction of the gas-solid mixture.
16. The boiler coal pretreatment method according to claim 12, further comprising passing a second pulverized coal stream into an ignition zone where the heat source (2) of the boiler coal pretreatment device ignites the air-powder mixture.
17. The boiler coal pretreatment method of claim 16, comprising switchably passing the first pulverized coal stream to the main reaction zone and/or passing the second pulverized coal stream to the ignition zone.
18. The boiler coal pretreatment process of claim 17, comprising adjustably passing said first pulverized coal stream and said second pulverized coal stream at different rates to said main reaction zone and said ignition zone.
19. A boiler comprising a boiler body and a boiler coal pretreatment device, characterized in that the boiler coal pretreatment device is a boiler coal pretreatment device according to any one of claims 1 to 11, and the main reaction chamber (3) is connected with a furnace of the boiler body (4) to introduce the products after the pyrolysis and gasification reaction into the furnace.
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