CN107044632B - Vertical pulverized coal boiler - Google Patents
Vertical pulverized coal boiler Download PDFInfo
- Publication number
- CN107044632B CN107044632B CN201710425369.0A CN201710425369A CN107044632B CN 107044632 B CN107044632 B CN 107044632B CN 201710425369 A CN201710425369 A CN 201710425369A CN 107044632 B CN107044632 B CN 107044632B
- Authority
- CN
- China
- Prior art keywords
- hearth
- pulverized coal
- secondary air
- furnace
- air
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- 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
- F23C7/00—Combustion apparatus characterised by arrangements for air supply
-
- 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
- F23C10/00—Fluidised bed combustion apparatus
- F23C10/002—Fluidised bed combustion apparatus for pulverulent solid fuel
-
- 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
- F23C10/00—Fluidised bed combustion apparatus
- F23C10/18—Details; Accessories
- F23C10/20—Inlets for fluidisation air, e.g. grids; Bottoms
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L9/00—Passages or apertures for delivering secondary air for completing combustion of fuel
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
Abstract
The invention discloses a vertical pulverized coal boiler, comprising: the hearth comprises side walls positioned at the periphery of the hearth, a hearth bottom positioned below the side walls, and a hearth cavity formed by surrounding the side walls and the hearth bottom; at least one pulverized coal burner comprising a main body and a burner outlet pipe extending from the main body, the main body being arranged below the bottom of the furnace, the burner outlet pipe extending upwards from the outside of the bottom of the furnace into the furnace cavity and being adapted to introduce a mixture of primary air and pulverized coal into the furnace cavity; and the secondary air distribution device is arranged in the bottom of the hearth and is suitable for introducing secondary air into the inner cavity of the hearth. The secondary air distribution device comprises a plurality of secondary air distribution pipes distributed at the bottom of the hearth, and a plurality of air outlet holes are formed in the pipe wall of each secondary air distribution pipe. The burner outlet pipe extends into a gap between the secondary air distribution pipes, so that the mixture of primary air and coal dust is mixed with the secondary air to form a wind-powder mixture which flows upwards in a plug flow overall manner in the inner cavity of the hearth.
Description
Technical Field
The invention relates to the field of boilers, in particular to a vertical pulverized coal boiler.
Background
The structure taking coal as a main energy source in China is difficult to change in the long time in the future, the annual coal consumption in China reaches 15 hundred million tons, 8 hundred million tons of coal are used for coal-fired thermal power generation, and 7 hundred million tons of coal are used for a coal-fired industrial boiler. With the improvement of the emission standard of the atmospheric pollutants of the coal-fired boiler, the efficient clean combustion technology of the coal is a necessary requirement for future development.
In addition, in the traditional combustion mode, the difference between the injection speed of primary air and secondary air in a hearth and the average speed of the section of the hearth is large, a large backflow area exists in the hearth, high-temperature flue gas can be sucked in the backflow area to preheat coal dust, but the control of the backflow area is complex, agglomeration of coal dust particles easily occurs in the backflow area, if the structure of an in-furnace flow field is poor, the slagging tendency of the hearth is large, and the safe and stable operation of a boiler is influenced.
Traditional combustion modes include tangential firing using a direct flow burner and swirl firing using a swirl burner. In the traditional combustion mode, primary air carries pulverized coal and is sprayed into a hearth at the speed of 20-30m/s, and secondary air surrounds the primary air and is sprayed into the hearth at the speed of 30-40m/s, so that the combustion mode of wind-packed powder is formed. The pulverized coal is burned intensively in a specific area, the local combustion temperature is high, and the original NOx emission value of pulverized coal combustion is high. For a pulverized coal boiler burning anthracite, the original NOx emission value exceeds 800mg/m < 3 >; for bituminous coal fired boilers, the original NOx emissions values typically exceed 400mg/m3, both of which greatly exceed the relevant emissions standards.
In addition, in the traditional combustion mode, the difference between the jet speed of primary air and secondary air in the hearth and the average speed of air flow on the cross section of the hearth is larger, a larger backflow area exists in the hearth, high-temperature flue gas can be sucked in the backflow area, coal dust is preheated, the control of the backflow area is complex, coal dust particle agglomeration easily occurs in the backflow area, if the structure of an in-furnace flow field is poor, the slagging tendency of the hearth is large, and the safe and stable operation of a boiler is influenced.
In addition, in the tangential firing mode or the cyclone firing mode of the pulverized coal, because the pulverized coal is burned intensively and releases heat, the pulverized coal combustion temperature exceeds the ash fusion point, the pulverized coal combustion is easy to form slag bonding, and part of slag is adhered to the water-cooled wall of the hearth to influence the heat transfer performance of the boiler. During operation of the boiler, part of the slag needs to be discharged from the bottom of the furnace, thus reducing the boiler efficiency.
Disclosure of Invention
In order to overcome at least one aspect of the above-mentioned prior art drawbacks, the present invention proposes a vertical pulverized coal boiler capable of achieving uniform and efficient combustion of pulverized coal, low nitrogen oxide emission, and avoiding accumulation of pulverized coal particles inside a furnace.
According to an aspect of the present invention, there is provided a vertical pulverized coal boiler, which may include: the hearth comprises side walls positioned at the periphery of the hearth, a hearth bottom positioned below the side walls, and a hearth cavity formed by surrounding the side walls and the hearth bottom; at least one pulverized coal burner comprising a main body disposed below the bottom of the furnace and a burner outlet tube extending from the main body, the burner outlet tube extending upwardly from the outside of the bottom of the furnace into the furnace cavity and being adapted to introduce a mixture of primary air and pulverized coal into the furnace cavity; the secondary air distribution device is arranged in the bottom of the hearth and is suitable for introducing secondary air into the inner cavity of the hearth, wherein the secondary air distribution device comprises a plurality of secondary air distribution pipes distributed at the bottom of the hearth, and a plurality of air outlet holes are formed in the pipe wall of each secondary air distribution pipe; and the burner outlet pipe extends into a gap between the secondary air distribution pipes, so that the mixture of the primary air and the pulverized coal is mixed with the secondary air in the inner cavity of the hearth to form an air-powder mixture which flows upwards in a plug flow overall manner in the inner cavity of the hearth.
According to an exemplary embodiment of the present invention, a hood is disposed in the air outlet hole of the secondary air distribution pipe.
According to another exemplary embodiment of the present invention, the furnace comprises a sidewall lower portion having a height of 20% -40% of the total height of the sidewall, the furnace sidewall lower portion being an inverted cone portion having a gradually increasing cross section from bottom to top.
According to another exemplary embodiment of the invention, the furnace comprises four side walls, wherein two opposite side walls are inclined inwardly at their lower portions, and the other two opposite side walls remain vertical in the vertical direction.
According to another exemplary embodiment of the invention, the furnace comprises four side walls, the middle and lower parts of which remain vertical, and the cross section of the middle and lower parts of which is substantially rectangular and the area remains unchanged, said middle and lower parts having a height of 20 to 40% of the total height of the side walls, respectively.
According to another exemplary embodiment of the present invention, the vertical pulverized coal boiler further includes: and the at least one layer of tertiary air nozzle is suitable for introducing tertiary air into the hearth and is arranged on the side wall of the hearth in a layered manner, and one layer of nozzle in the at least one layer of tertiary air nozzle is arranged on the lower part of the side wall of the hearth.
According to another exemplary embodiment of the present invention, the secondary air distribution device is provided at the bottom of the furnace to be distributed over the entire cross section of the bottom of the furnace.
According to another exemplary embodiment of the present invention, a center-to-center distance between hoods on the secondary air distribution duct and a distance between the ducts is not more than 300mm.
According to another exemplary embodiment of the present invention, the plurality of secondary air distribution pipes are parallel to each other and traverse the side wall near the bottom of the furnace so that both ends thereof are located outside the furnace, and one end of the secondary air distribution pipe is in fluid communication with the secondary air main pipe, and the other end is provided with a detachable plug.
According to another exemplary embodiment of the present invention, the injection momentum of the secondary air is less than or equal to the injection momentum of the mixture of the primary air and the pulverized coal.
According to another exemplary embodiment of the present invention, the injection momentum of the secondary air is between 70% and 90% of the injection momentum of the mixture of the primary air and the pulverized coal.
According to another exemplary embodiment of the present invention, the pulverized coal burner is a pulverized coal preheating burner to preheat a mixture of primary air and pulverized coal to 850 ℃ or more.
According to another aspect of the present invention, there is provided a pulverized coal combustion method for a vertical pulverized coal boiler, the pulverized coal boiler including: the hearth comprises side walls positioned at the periphery of the hearth, a hearth bottom positioned below the side walls, and a hearth cavity formed by surrounding the side walls and the hearth bottom; at least one pulverized coal burner comprising a main body disposed below the bottom of the furnace and a burner outlet tube extending from the main body, the burner outlet tube extending upwardly from the outside of the bottom of the furnace into the furnace cavity and being adapted to introduce a mixture of primary air and pulverized coal into the furnace cavity; the secondary air distribution device is arranged in the bottom of the hearth and is suitable for introducing secondary air into the inner cavity of the hearth, wherein the secondary air distribution device comprises a plurality of secondary air distribution pipes distributed at the bottom of the hearth, and a plurality of air outlet holes are formed in the pipe wall of each secondary air distribution pipe; and the burner outlet tube extends into the gap between the overgrate air ductwork, the method comprising: and introducing a mixture of primary air and pulverized coal into the inner cavity of the furnace from the bottom of the furnace through at least one pulverized coal burner, and introducing secondary air into the inner cavity of the furnace from the bottom of the furnace through a secondary air distribution device, so that the mixture of primary air and pulverized coal and the secondary air are mixed in the inner cavity of the furnace to form an air-powder mixture flowing upwards in a plug flow integrally so as to burn at the same temperature in the inner cavity of the furnace.
According to an exemplary embodiment of the present invention, the mixture of the primary air and the pulverized coal is preheated to 850 ℃ or more by a pulverized coal burner.
According to another exemplary embodiment of the present invention, the injection momentum of the secondary air is between 70% and 90% of the injection momentum of the mixture of the primary air and the pulverized coal.
According to another exemplary embodiment of the present invention, the secondary air is air or a mixture of air and flue gas.
According to the vertical pulverized coal boiler provided by the embodiment of the invention, the secondary air is provided by the secondary air distribution pipe arranged on the whole cross section of the bottom of the hearth, the air supply is uniform, entrainment and backflow hardly occur, and the speed difference of each part on the cross section of the hearth is small, so that the dispersed air-powder mixture integrally flows upwards after being mixed with the mixture of the primary air and the pulverized coal, and the conventional air-powder combustion mode is changed. Therefore, the invention realizes the overall upward thrust flow of the wind-powder mixture in the whole hearth space, no reflux area appears in the hearth, the accumulation of coal powder particles in the hearth is avoided, and the running stability of the system is improved.
Drawings
The invention may be best understood from the following detailed description of various embodiments of the invention when read in connection with the accompanying drawings, wherein:
fig. 1 is a schematic view of a furnace of a vertical pulverized coal boiler according to the present invention.
Fig. 2 is a plan view of the bottom of a furnace of a vertical pulverized coal boiler according to the present invention.
Fig. 3 is a sectional view of a secondary air distribution pipe of a vertical pulverized coal boiler according to the present invention.
Detailed Description
The technical scheme of the invention is further specifically described below through examples and with reference to the accompanying drawings. In the specification, the same or similar reference numerals denote the same or similar components. The following description of embodiments of the present invention with reference to the accompanying drawings is intended to illustrate the general inventive concept and should not be taken as limiting the invention.
Furthermore, in the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments disclosed herein. It may be evident, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in the drawings in order to simplify the drawings.
In the embodiment shown in fig. 1 and 2, the present invention provides a vertical pulverized coal boiler including: the furnace 1 comprises side walls 11 positioned at the periphery of the furnace, a furnace bottom 12 positioned below the side walls, and a furnace cavity 13 formed by surrounding the side walls and the furnace bottom; at least one pulverized coal burner 5 comprising a main body 52 arranged below the bottom 12 of the furnace and a burner outlet pipe 51 extending from the main body, said burner outlet pipe 51 extending from the outside of the bottom of the furnace upwards into the furnace cavity and being adapted to feed a mixture of primary air and pulverized coal into the furnace cavity 13; the secondary air distribution device 2 is arranged in the bottom of the hearth and is suitable for introducing secondary air into the inner cavity of the hearth, wherein the secondary air distribution device comprises a plurality of secondary air distribution pipes 2 distributed at the bottom of the hearth, and a plurality of air outlet holes 21 are formed in the pipe wall of each secondary air distribution pipe; and the burner outlet pipe 51 extends into the gap between the secondary air distribution pipes 2. In an exemplary embodiment of the invention, the cloth duct 2 occupies substantially the entire cross section of the bottom of the furnace. Since the secondary air is supplied from the substantially entire cross section of the bottom of the furnace, the speed difference is small at all parts of the cross section of the furnace, and therefore, the primary air and the pulverized coal mixture and the secondary air form a dispersed air-powder mixture without entrainment and backflow, and therefore, the air-powder mixture flows upwards in a plug flow, thereby changing the conventional air-bag powder combustion mode.
In an exemplary embodiment according to the present invention, the secondary air distribution duct 2 includes a set of secondary air ducts 2 parallel to each other and a total air duct 20 in fluid communication with the plurality of secondary air ducts, and a hood (not shown) may be provided in an air outlet hole 21 of the secondary air duct 2, a center distance between the hood and a distance between the air ducts parallel to each other being not more than 300mm, and the secondary air distribution means is provided at the bottom of the furnace so as to be distributed over the entire cross section of the bottom of the furnace so that secondary air is uniformly fed into the inner cavity of the furnace from almost the entire cross section of the bottom of the furnace. In one example, the plurality of overgrate air distribution pipes 2 are parallel to each other across the side wall 11 near the bottom of the furnace so that both ends are located outside the furnace, one end of the overgrate air distribution pipes being in fluid communication with the overgrate air main 20 and the other end being provided with a removable plug 22.
When the boiler is provided with only one preheating burner 51, the burner outlet pipe 51 is preferably positioned at the center of the group of secondary air distribution pipes 2 and is surrounded by the air outlet holes 21 on the secondary air distribution pipes; when the boiler is provided with a plurality of burners 5, the burner outlet pipes 51 are preferably evenly distributed between the secondary air distribution pipes 2, with a number of air outlet holes 21 in the secondary air distribution pipes 2 being spaced apart from each other, such that each burner outlet pipe 51 is surrounded by an air outlet hole 21 in the secondary air distribution pipe 2. Because the plurality of secondary air distribution pipes 2 and the air outlet holes 21 thereon extend over the entire cross section of the bottom of the furnace, in one example, the number of the air outlet holes 21 may be hundreds, and thus the outlet pipe of the burner is surrounded by the plurality of air outlet holes 21, regardless of whether one or several preheating burners 5 are provided, instead of merely arranging a considerable number of secondary air passages around the primary air passages of the burners arranged on the side walls of the furnace, as in conventional direct-current burners or cyclone burners. In the conventional burner, it is generally necessary to arrange the secondary air duct closely around the primary air duct because only the wind thus blown out from the secondary air duct can tightly surround the mixture of the primary air and the pulverized coal, so that the pulverized coal is not easily diffused, thereby more facilitating ignition of the pulverized coal in a local area by means of high temperature inside the boiler. However, in the embodiment according to the present invention, the provision of the number of the air outlet holes 21, which is much larger in number than the number of the burner outlet pipes 51, in the region between the plurality of burner outlet pipes or in the vicinity of one burner outlet pipe enables the secondary air to be more uniformly sprayed at the bottom of the furnace and to be more easily uniformly mixed with the mixture of primary air and pulverized coal, instead of being tightly enclosed in the mixture of primary air and pulverized coal. It should be noted that the number of the secondary air distribution pipes 2 and the air outlet holes 21 thereon and the number of the burners 5 may vary according to the actual needs and the area of the cross section of the bottom of the furnace, and the secondary air distribution pipes 2 may not be parallel to each other, such as a star-shaped arrangement.
In an exemplary embodiment according to the present invention, as shown in fig. 1, the cross-sectional area of the furnace may remain unchanged. Specifically, in one example, the firebox includes four side walls, the middle and lower portions of which remain vertical and have a generally rectangular cross-section with an area that remains constant, wherein the middle and lower portions respectively account for 20% to 40% of the overall height of the firebox side walls. It is to be understood that the cross-section of the furnace of the present invention is not limited to a rectangular cross-section, and that the cross-section of the furnace may be circular, rectangular, other polygonal, etc.
In addition, although not shown in fig. 1, one skilled in the art will appreciate: the side wall 11 of the hearth 1 comprises a side wall lower part 111 with the height being 20% -40% of the total height of the side wall, and the side wall lower part 111 is an inverted cone part with the cross section gradually becoming larger from bottom to top. In particular, in one example, the side walls include four pieces of side walls, wherein two opposite pieces of side walls are inclined inwardly at lower portions thereof to be inverted cone-shaped, and the other two opposite pieces of side walls remain upright in a vertical direction.
In an exemplary embodiment according to the present invention, the vertical pulverized coal boiler further comprises at least one layer of tertiary air nozzles 6 adapted to introduce tertiary air into the furnace and arranged in layers on the side walls 11 of the furnace, one layer of the at least one layer of tertiary air nozzles 6 being arranged on the lower part 111 of the side walls 11 of the furnace, combustion of pulverized coal being maintained by the tertiary air fed into the interior of the furnace and the cross-sectional velocity of the furnace being maintained at not less than 2.0m/s.
In an exemplary embodiment according to the present invention, the injection momentum of the secondary air is less than or equal to the injection momentum of the mixture of the primary air and the pulverized coal. Further, the jet momentum of the secondary air is 70% to 90% of the jet momentum of the mixture of the primary air and the pulverized coal. The mixing of the secondary air and the mixture of the primary air and the pulverized coal is facilitated by making the injection momentum of the secondary air slightly smaller than that of the mixture of the primary air and the pulverized coal, so that the combustion is facilitated more, and the secondary air reaches the upper part of the hearth earlier than the mixture of the primary air and the pulverized coal. In the process that the air-powder mixture flows upwards from the lower space of the inner cavity of the hearth, partial combustion reaction occurs, heat released by the combustion of the pulverized coal is transferred to the water-cooled walls around the bottom of the hearth, and along with the increase of the height of the hearth and the expansion of the sectional area of the hearth, the combustion of the pulverized coal is maintained by means of tertiary air fed into the hearth, and the section speed of the hearth is kept to be not lower than 2.0m/s.
In one embodiment according to the invention, the pulverized coal burner adopts a circulating fluidized bed preheating burner, pulverized coal carried by primary air can be preheated to 800-850 ℃ or even higher in the circulating fluidized bed preheating burner, the pulverized coal is ignited in the burner, and the preheated pulverized coal is quickly mixed with secondary air after being introduced into a hearth and is stably combusted. At this time, primary air and pulverized coal which are introduced into a hearth through a pulverized coal burner are precisely high-temperature powdery fuel formed after the pulverized coal is partially combusted and high-temperature gas containing a large amount of combustible components. However, as for ignition of the pulverized coal, it is understood by those skilled in the art that, instead of preheating the burner or the like to bring the pulverized coal into the furnace to the ignition temperature, plasma ignition or other treatment of the pulverized coal to lower the ignition point may be employed.
When the boiler operates, a mixture of primary air and coal dust is introduced into the inner cavity 13 of the furnace from the bottom 12 of the furnace through the coal dust burner 5, secondary air is introduced into the furnace from the bottom of the furnace through the secondary air outlet 21, and tertiary air is introduced into the furnace through the tertiary air nozzle. Because the secondary air is evenly supplied to the inner cavity of the hearth and matched with reasonable jet momentum of the primary air and the secondary air, the mixture of the primary air and the pulverized coal is mixed with the secondary air strongly and evenly at the bottom of the hearth, namely above the secondary air distribution pipe 2, entrainment and backflow hardly occur, and the speed difference of each part on the cross section of the hearth is small, the dispersed air-powder mixture integrally flows upwards, namely the air-powder mixture flows upwards in a plug flow way, so that the conventional air-powder combustion mode is changed. The air-powder mixture fills the inner cavity of the hearth, the combustion mode of the pulverized coal is full-field space combustion in the hearth, and the staged combustion and the uniform temperature control of the pulverized coal are realized in the full-field space of the hearth by combining the air distribution control of tertiary air.
The tertiary air for pulverized coal combustion is added along the height of the hearth in multiple layers, the reducing atmosphere is arranged below the top layer nozzle of the tertiary air, and fuel nitrogen released in pulverized coal combustion is converted into multidirectional nitrogen. Because the concentrated combustion area does not exist in the pulverized coal combustion, the highest temperature level of the pulverized coal combustion is low, and thermal NOx is basically not generated in the pulverized coal combustion. Thus, the original emission level of NOx is much lower than conventional pulverized coal combustion technology.
In addition, as the hearth is internally provided with a horizontal plug flow which integrally flows upwards, the section speed of the hearth is controlled not to be too low, pulverized coal is not lost, the uniform temperature is controlled, and the worry that the powder deposition and slag discharge at the bottom of the hearth fall into an air chamber is not needed, so that a blast cap is not needed, secondary air is directly provided through small holes on a secondary air distribution pipe, and the small holes on the secondary air distribution pipe are basically uniformly arranged at the moment, and the distance is not more than 300mm.
In addition, the invention also provides a pulverized coal combustion method, which adopts the vertical pulverized coal burner, and the pulverized coal boiler comprises the following steps: the hearth comprises side walls positioned at the periphery of the hearth, a hearth bottom positioned below the side walls, and a hearth cavity formed by surrounding the side walls and the hearth bottom; at least one pulverized coal burner comprising a main body disposed below the bottom of the furnace and a burner outlet tube extending from the main body, the burner outlet tube extending upwardly from the outside of the bottom of the furnace into the furnace cavity and being adapted to introduce a mixture of primary air and pulverized coal into the furnace cavity; the secondary air distribution device is arranged in the bottom of the hearth and is suitable for introducing secondary air into the inner cavity of the hearth, wherein the secondary air distribution device comprises a plurality of secondary air distribution pipes distributed at the bottom of the hearth, and a plurality of air outlet holes are formed in the pipe wall of each secondary air distribution pipe; and the burner outlet tube extends into the gap between the overgrate air ductwork, the method comprising: and introducing a mixture of primary air and pulverized coal into the inner cavity of the furnace from the bottom of the furnace through at least one pulverized coal burner, and introducing secondary air into the inner cavity of the furnace from the bottom of the furnace through a secondary air distribution device, so that the mixture of primary air and pulverized coal and the secondary air are mixed in the inner cavity of the furnace to form an air-powder mixture flowing upwards in a plug flow integrally so as to burn at the same temperature in the inner cavity of the furnace.
On the basis of the vertical pulverized coal boiler according to the embodiment of the present invention, several experiments were performed to exemplarily better illustrate the technical effects of the boiler according to the present invention, and the specific experiments are as follows:
test 1
On the basis of the vertical pulverized coal boiler provided by the embodiment of the invention, the fuel is bituminous coal powder, the granularity of the pulverized coal is below 200 mu m, the secondary air is the mixed gas of preheated air and flue gas recirculation, the oxygen content is 15%, and the temperature is 150 ℃; the tertiary air is preheated air, and the air temperature is 150 ℃; the combustion efficiency of the bituminous coal powder is 99.2%, the original NOx emission value is 120mg/Nm3, the original NOx emission value is obviously reduced, and the high-efficiency low-nitrogen combustion of the bituminous coal is realized.
Test 2
On the basis of the vertical pulverized coal boiler provided by the embodiment of the invention, the fuel is semicoke powder with very low volatile matters, and a circulating fluidized bed type preheating burner is adopted to spray a mixture of the semicoke powder preheated to 850 ℃ and primary air into a hearth; the temperature of the secondary air is 200 ℃; the apparent velocity of the coke powder air flow in the hearth is 3.0m/s, and the combustion temperature of the hearth is 1100 ℃; along the height direction of the hearth, two layers of tertiary air are arranged. The test result shows that the combustion efficiency of semicoke is 96.5%, the original emission level of NOx is 50mg/Nm3, the original emission value of NOx is obviously reduced, and the high-efficiency low-nitrogen combustion of low-volatile flame-retardant fuel is realized.
Therefore, in the vertical pulverized coal boiler according to the embodiment of the invention, the secondary air is provided by adopting the secondary air distribution pipe arranged on the whole cross section of the bottom of the hearth, the air supply is uniform, entrainment and backflow hardly occur, and the speed difference of each part on the cross section of the hearth is small, so that the dispersed air-powder mixture integrally flows upwards, and the conventional air-bag powder combustion mode is changed. Therefore, the invention realizes the overall upward thrust flow of the wind-powder mixture in the whole hearth space, no reflux area appears in the hearth, the accumulation of coal powder particles in the hearth is avoided, and the running stability of the system is improved.
Furthermore, the invention breaks through the wind powder-wrapping mode of the conventional burner, so that the combustion temperature of the pulverized coal in the whole hearth space is uniformly distributed, and the highest temperature of pulverized coal combustion is stabilized, so that the uniform temperature combustion can be realized, the current situations of concentrated combustion and concentrated heat release of the conventional combustion mode can be changed, the concentrated high temperature area in the furnace in the conventional pulverized coal combustion mode is eliminated, and thermal NOx is not generated.
Furthermore, because the uniform temperature combustion is realized in the inner cavity of the hearth, the highest temperature in the furnace is lower than the ash fusion point by the uniform temperature combustion of the pulverized coal, slag bonding is avoided, and fly ash generated by the combustion of the pulverized coal enters the tail part along with the flue gas, so that slag discharge is not needed in the operation of the boiler, the thermal efficiency of the boiler is high, and the system is simple to operate.
Furthermore, the pulverized coal is combusted at the uniform temperature, so that the temperature of the hearth is uniformly distributed, the average temperature in the furnace is higher than that of the conventional combustion mode, the radiation heat transfer capacity in the furnace is enhanced, the volume of the boiler can be reduced, and the manufacturing cost of the boiler is saved.
Although embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.
Claims (13)
1. A vertical pulverized coal fired boiler comprising:
the hearth comprises side walls positioned at the periphery of the hearth, a hearth bottom positioned below the side walls, and a hearth cavity formed by surrounding the side walls and the hearth bottom;
at least one pulverized coal burner comprising a main body disposed below the bottom of the furnace and a burner outlet tube extending from the main body, the burner outlet tube extending upwardly from the outside of the bottom of the furnace into the furnace cavity and being adapted to introduce a mixture of primary air and pulverized coal into the furnace cavity; and
the secondary air distribution device is arranged in the bottom of the hearth and is suitable for introducing secondary air into the inner cavity of the hearth,
the secondary air distribution device comprises a plurality of secondary air distribution pipes distributed at the bottom of the hearth, and a plurality of air outlet holes are formed in the pipe wall of each secondary air distribution pipe; and
the burner outlet pipe extends into a gap between the secondary air distribution pipes, so that the mixture of primary air and coal dust is mixed with the secondary air in the inner cavity of the hearth to form an air-powder mixture which flows upwards in a plug flow overall manner in the inner cavity of the hearth;
the secondary air distribution device is arranged at the bottom of the hearth and distributed on the whole cross section of the bottom of the hearth; the jet momentum of the secondary air is smaller than or equal to the jet momentum of the mixture of the primary air and the pulverized coal; and a hood is arranged in the air outlet of the secondary air distribution pipe.
2. The vertical pulverized coal boiler according to claim 1, wherein the furnace comprises a sidewall lower portion having a height of 20% -40% of a total height of the sidewall, and the furnace sidewall lower portion is an inverted cone portion having a cross section gradually increasing from bottom to top.
3. The vertical pulverized coal boiler as claimed in claim 2, wherein the furnace comprises four side walls, wherein two opposite side walls are inclined inwardly at lower portions thereof, and the other two opposite side walls remain vertical in a vertical direction.
4. The vertical pulverized coal boiler as claimed in claim 1, wherein the furnace comprises four side walls, the middle and lower parts of which are kept vertical, and the cross section of the middle and lower parts of the side walls of the furnace is substantially rectangular and the area is kept constant, the height of the middle and lower parts respectively accounting for 20 to 40% of the total height of the side walls.
5. The vertical pulverized coal boiler according to claim 2 or 4, further comprising: and the at least one layer of tertiary air nozzle is suitable for introducing tertiary air into the hearth and is arranged on the side wall of the hearth in a layered manner, and one layer of nozzle in the at least one layer of tertiary air nozzle is arranged on the lower part of the side wall of the hearth.
6. The vertical pulverized coal boiler according to claim 1, wherein a center-to-center distance between hoods on the secondary air distribution pipes and a distance between the pipes are not more than 300mm.
7. The vertical pulverized coal fired boiler according to claim 1, wherein the plurality of secondary air distribution pipes are parallel to each other and transversely penetrate through the side wall near the bottom of the furnace so that both ends of the secondary air distribution pipes are positioned outside the furnace, one end of each secondary air distribution pipe is in fluid communication with the secondary air main pipe, and the other end of each secondary air distribution pipe is provided with a detachable plug.
8. The vertical pulverized coal boiler according to claim 1, wherein the injection momentum of the secondary air is between 70% and 90% of the injection momentum of the mixture of primary air and pulverized coal.
9. The vertical pulverized coal boiler according to claim 1, wherein the pulverized coal burner is a pulverized coal preheating burner to preheat a mixture of primary air and pulverized coal to 850 ℃ or more.
10. A pulverized coal combustion method for a vertical pulverized coal boiler, the pulverized coal boiler comprising: the hearth comprises side walls positioned at the periphery of the hearth, a hearth bottom positioned below the side walls, and a hearth cavity formed by surrounding the side walls and the hearth bottom; at least one pulverized coal burner comprising a main body disposed below the bottom of the furnace and a burner outlet tube extending from the main body, the burner outlet tube extending upwardly from the outside of the bottom of the furnace into the furnace cavity and being adapted to introduce a mixture of primary air and pulverized coal into the furnace cavity; the secondary air distribution device is arranged in the bottom of the hearth and is suitable for introducing secondary air into the inner cavity of the hearth, and the secondary air distribution device is arranged at the bottom of the hearth so as to be distributed on the whole cross section of the bottom of the hearth; the secondary air distribution device comprises a plurality of secondary air distribution pipes distributed at the bottom of the hearth, a plurality of air outlet holes are formed in the pipe wall of each secondary air distribution pipe, and an air cap is arranged in each air outlet hole of each secondary air distribution pipe; and the burner outlet tube extends into the gap between the overgrate air ductwork, the method comprising:
introducing a mixture of primary air and pulverized coal into the inner cavity of the hearth from the bottom of the hearth through at least one pulverized coal burner,
and introducing secondary air into the inner cavity of the furnace from the bottom of the furnace through a secondary air distribution device, so that the mixture of the primary air and the pulverized coal is mixed with the secondary air in the inner cavity of the furnace to form an air-powder mixture which flows upwards in a plug flow integrally so as to burn in the inner cavity of the furnace at the uniform temperature, and the injection momentum of the secondary air is smaller than or equal to that of the mixture of the primary air and the pulverized coal.
11. The method of claim 10, wherein,
the mixture of primary air and pulverized coal is preheated to 850 ℃ or above by a pulverized coal burner.
12. The method of claim 10, wherein,
the jet momentum of the secondary air is between 70% and 90% of the jet momentum of the mixture of the primary air and the pulverized coal.
13. The method of claim 10, wherein,
the secondary air is air or mixed gas of air and flue gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710425369.0A CN107044632B (en) | 2017-06-07 | 2017-06-07 | Vertical pulverized coal boiler |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710425369.0A CN107044632B (en) | 2017-06-07 | 2017-06-07 | Vertical pulverized coal boiler |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107044632A CN107044632A (en) | 2017-08-15 |
| CN107044632B true CN107044632B (en) | 2023-09-12 |
Family
ID=59546310
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710425369.0A Active CN107044632B (en) | 2017-06-07 | 2017-06-07 | Vertical pulverized coal boiler |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107044632B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110160039A (en) * | 2018-02-14 | 2019-08-23 | 兖矿中科清洁能源科技有限公司 | Overhead burner pulverized-coal fired boiler and its control method |
| CN108503174A (en) * | 2018-04-17 | 2018-09-07 | 湖南省益能环保科技有限公司 | A kind of gasification installation for Treatment of Sludge |
| CN111121002A (en) * | 2018-11-01 | 2020-05-08 | 中国科学院工程热物理研究所 | Pulverized coal fired boiler with bottom burner and control method thereof |
| CN111121003A (en) * | 2018-11-01 | 2020-05-08 | 中国科学院工程热物理研究所 | Burner bottom-mounted pulverized coal fired boiler with wall-attached air and control method thereof |
| CN112443833B (en) * | 2019-09-05 | 2023-01-06 | 中国科学院工程热物理研究所 | Pulverized coal fired boiler with bottom-mounted burner and control method thereof |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1119039A (en) * | 1993-03-08 | 1996-03-20 | 欧文·W·戴克马 | Coal combustion process for SOx and NOx control |
| CN2388547Y (en) * | 1999-07-13 | 2000-07-19 | 乔俊哲 | High-efficient pollutionless boiler |
| CN104791775A (en) * | 2015-04-10 | 2015-07-22 | 中国科学院工程热物理研究所 | Vertical pulverized coal boiler with burner arranged at bottom |
| CN104832915A (en) * | 2015-01-30 | 2015-08-12 | 武汉凯迪工程技术研究总院有限公司 | Method of blending combustion of fuel coal fly ash in biomass circulating fluidized bed boiler and a device thereof |
| JP2015215119A (en) * | 2014-05-09 | 2015-12-03 | 株式会社Ihi | Burner |
| CN206861509U (en) * | 2017-06-07 | 2018-01-09 | 中国科学院工程热物理研究所 | Vertical pulverized-coal fired boiler |
-
2017
- 2017-06-07 CN CN201710425369.0A patent/CN107044632B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1119039A (en) * | 1993-03-08 | 1996-03-20 | 欧文·W·戴克马 | Coal combustion process for SOx and NOx control |
| CN2388547Y (en) * | 1999-07-13 | 2000-07-19 | 乔俊哲 | High-efficient pollutionless boiler |
| JP2015215119A (en) * | 2014-05-09 | 2015-12-03 | 株式会社Ihi | Burner |
| CN104832915A (en) * | 2015-01-30 | 2015-08-12 | 武汉凯迪工程技术研究总院有限公司 | Method of blending combustion of fuel coal fly ash in biomass circulating fluidized bed boiler and a device thereof |
| WO2016119670A1 (en) * | 2015-01-30 | 2016-08-04 | 武汉凯迪工程技术研究总院有限公司 | Blend combustion method of fuel coal fly ash for biomass circulating fluidized bed boiler and device thereof |
| CN104791775A (en) * | 2015-04-10 | 2015-07-22 | 中国科学院工程热物理研究所 | Vertical pulverized coal boiler with burner arranged at bottom |
| CN206861509U (en) * | 2017-06-07 | 2018-01-09 | 中国科学院工程热物理研究所 | Vertical pulverized-coal fired boiler |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107044632A (en) | 2017-08-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107044632B (en) | Vertical pulverized coal boiler | |
| PL206626B1 (en) | Solid fuel burner and combustion method using solid fuel burner | |
| CN107023824B (en) | Vertical pulverized coal boiler | |
| CN107044633B (en) | Vertical pulverized coal boiler | |
| CN104791775A (en) | Vertical pulverized coal boiler with burner arranged at bottom | |
| CN110425520B (en) | Flameless combustion system for semi-coke type flame-retardant fuel | |
| CN111928237A (en) | Mixed combustion nozzle based on mixed combustion chemical waste gas of circulating fluidized bed boiler and mixed combustion method | |
| JP2002243108A (en) | Mixed-fuel fired device of coal and biofuel and operating method thereof | |
| CN103697465A (en) | Boiler capable of achieving reignition of exhaust gas coal powder and reducing NOx by using high-temperature flue gas | |
| CN101280920B (en) | Fluidization-suspension combined combustion boiler | |
| CN107013903B (en) | Vertical pulverized coal boiler | |
| CN211502751U (en) | Combustion apparatus | |
| EP3535521B1 (en) | Multi chamber incinerator for turbulent combustion of solid and biomass fuel | |
| CN109000219B (en) | Vertical pulverized coal boiler | |
| CN112443833B (en) | Pulverized coal fired boiler with bottom-mounted burner and control method thereof | |
| CN206861509U (en) | Vertical pulverized-coal fired boiler | |
| CN101196294A (en) | Fluidization-suspending two-stage type compound combustion device | |
| CN116025893A (en) | Preheating burner with heating surface | |
| CN206861510U (en) | Vertical pulverized-coal fired boiler | |
| CN205782895U (en) | A kind of modular multijet combustible powder burner | |
| CN206861512U (en) | Vertical pulverized-coal fired boiler | |
| CN111121002A (en) | Pulverized coal fired boiler with bottom burner and control method thereof | |
| RU2282105C2 (en) | Solid fuel burner (variants), fuel combustion device (variants), boiler (variants), fuel combustion method (variants), boiler system and power plant (variants) | |
| CN206861511U (en) | Vertical pulverized-coal fired boiler | |
| CN208936144U (en) | A kind of low nitrogen type circulating fluidized bed boiler based on optimization burning |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| TA01 | Transfer of patent application right |
Effective date of registration: 20181010 Address after: 100190 North Fourth Ring Road, Haidian District, Beijing, 11 Applicant after: Institute of Engineering Thermophysics, Chinese Academy of Sciences Applicant after: YANKUANG GROUP Co.,Ltd. Address before: 100190 North Fourth Ring Road, Haidian District, Beijing, 11 Applicant before: Institute of Engineering Thermophysics, Chinese Academy of Sciences |
|
| TA01 | Transfer of patent application right | ||
| TA01 | Transfer of patent application right |
Effective date of registration: 20181227 Address after: 273516 No. 16 Gongjian Road, Beishu Town, Zoucheng City, Jining City, Shandong Province Applicant after: YANKUANG GROUP ZHONGKE CLEANING ENERGY TECHNOLOGY Co.,Ltd. Address before: 100190 North Fourth Ring Road, Haidian District, Beijing, 11 Applicant before: Institute of Engineering Thermophysics, Chinese Academy of Sciences Applicant before: YANKUANG GROUP Co.,Ltd. |
|
| TA01 | Transfer of patent application right | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |