CN113324242B - W-flame boiler adopting circulating flue gas type gap type direct-current pulverized coal burner - Google Patents
W-flame boiler adopting circulating flue gas type gap type direct-current pulverized coal burner Download PDFInfo
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- CN113324242B CN113324242B CN202110679429.8A CN202110679429A CN113324242B CN 113324242 B CN113324242 B CN 113324242B CN 202110679429 A CN202110679429 A CN 202110679429A CN 113324242 B CN113324242 B CN 113324242B
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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
- F23C5/00—Disposition of burners with respect to the combustion chamber or to one another; Mounting of burners in combustion apparatus
- F23C5/08—Disposition of burners
Abstract
A W flame boiler adopting a circulating smoke type gap type direct-current pulverized coal burner relates to the technical field of boiler combustion. The invention solves the problems of high NOx emission concentration, poor stable combustion, high fly ash combustible content, over-temperature of the water-cooled wall of the lower hearth, large wall temperature deviation and slag bonding of the existing W flame boiler. A plurality of direct-flow pulverized coal burners are symmetrically arranged on a front arch and a rear arch by taking the central line of a hearth as a center, a light pulverized coal airflow nozzle is arranged on the side close to a water cooling wall, a main circulation flue gas nozzle is arranged on the side, close to the central line of the direct-flow pulverized coal burner, of a thick pulverized coal airflow nozzle and a light pulverized coal airflow nozzle, a secondary air nozzle is arranged on the side, far away from the central line of the direct-flow pulverized coal burner, of the thick pulverized coal airflow nozzle and the light pulverized coal airflow nozzle, and an outer circulation flue gas nozzle is arranged on the side close to the water cooling wall along the width direction of the hearth. The invention is used for reducing the NOx discharge amount at the outlet of the hearth, enhancing the stable combustion and burnout of the pulverized coal, reducing the ultra-high temperature and thermal deviation of the water-cooled walls on the front wall and the rear wall of the lower hearth and preventing the water-cooled walls from slagging.
Description
Technical Field
The invention relates to the technical field of boiler combustion, in particular to a W flame boiler adopting a circulating smoke type gap type direct-flow pulverized coal burner.
Background
With the vigorous development of economic society in China, the demand of power resources is continuously expanding. In recent years, the development speed of various new energy industries such as wind power generation, hydroelectric power generation, solar power generation and the like is rapidly increased, and the new energy industries also occupy certain market share, but the related technologies have not made breakthrough progress due to the limitation of natural resources and geographical environments in China, and the coal-fired thermal power generation is still the most important power generation form in the power industry. The low volatile coal is anthracite and lean coal which account for more than 40 percent of the coal used for boiler combustion in power stations in China. The low volatile coal is not easy to ignite and difficult to burn out, so that the foreign four-corner tangential liquid slag discharging furnace is introduced in the last 60 th century, and the difficult-to-burn coal is combusted by adopting a wall type opposed firing boiler in the last 90 th century, meanwhile, the W flame boiler is introduced in China, so that the high-efficiency combustion efficiency enables the difficult-to-burn coal to quickly occupy the market, and the W flame boiler is quickly developed in decades and becomes a main furnace type for combusting the difficult-to-burn coal in the domestic coal-fired power station.
W flame boilers are widely applied in China, but some problems are still exposed in actual operation, and more serious and common NO existsxHigh emission, poor stable combustion, high content of combustible substances in fly ash, over-temperature of a water cooled wall of a lower hearth, large wall temperature deviation and serious slag bonding. NOxThe high emission is because the pulverized coal combustion in the W flame boiler is carried out under the condition of high temperature and oxygen enrichment and can promote fuel NOxAlthough the thick and thin combustion measures have certain improvement effect, the difference from the theory real realization is large. In actual operation, in order to reduce fuel cost, the actual coal quality for burning of the boiler is sometimes poorer than the designed coal quality, for example, poor-quality coal with high combustion ash content and dry base ash content Ad larger than 40 percent belongs to coal which is extremely difficult to stably burn and is difficult to burn out in a medium mode. When the boiler burns the inferior coal with high ash content, the pulverized coal is late in ignition and poor in stable combustion, and the pulverized coal is hard to be completely burnt, so that the combustible content of the fly ash is higher. The W flame boiler adopts a vertical tube panel type water-cooled wall, and because the size of a lower hearth is large, the number of parallel tube panels of the water-cooled wall is large, the corresponding geothermal deviation is large, and the W flame boiler is sensitive to the deviation of the thermal load of the hearth. The uneven distribution of the local heat load of the water-cooled wall can cause the overtemperature of the water-cooled wall to cause tube explosion, the wall temperature deviation is large, fins are pulled to crack, and the safe operation of the boiler is influenced. Meanwhile, the unreasonable distribution of secondary air on the arch can also lead to different ignition point positions of burners arranged along the width direction of the hearth, the downward-thrust depth of flame of the burners is different, and the wall temperature deviation of the water-cooled wall of the front wall and the rear wall along the width direction of the hearth is large. The slag bonding is serious because the temperature of the lower hearth of the W flame boiler is higher, and the temperature near the water-cooled wall is also higher under the condition that no secondary air or low-temperature circulating flue gas is cooled near the water-cooled wall, so that the slag bonding is easy to occur.
In conclusion, the existing W flame boiler has the problems of high NOx emission concentration, poor stable combustion, high fly ash combustible content, over-temperature of a water-cooled wall of a lower hearth, large wall temperature deviation and slag bonding.
Disclosure of Invention
The invention aims to solve the problems of high NOx emission concentration, poor stable combustion, high fly ash combustible content, over-temperature of a water-cooled wall of a lower hearth, large wall temperature deviation and slag bonding of the conventional W flame boiler, and further provides the W flame boiler adopting the circulating smoke type gap type direct-flow pulverized coal burner.
The technical scheme of the invention is as follows:
a W flame boiler adopting a circulating flue gas type gap type direct-flow pulverized coal burner comprises an upper hearth 1 and a lower hearth 5, wherein the lower hearth 5 comprises a front arch 2, a rear arch 3, a front wall 4, a rear wall 7, a cold ash hopper 6 and a plurality of direct-flow pulverized coal burners, the direct-flow pulverized coal burners are the circulating flue gas type gap type direct-flow pulverized coal burners, the plurality of direct-flow pulverized coal burners are symmetrically arranged on the front arch 2 and the rear arch 3 by taking a hearth central line 1-1 as a center, the plurality of direct-flow pulverized coal burners are communicated with the lower hearth 5, each direct-flow pulverized coal burner comprises a dense pulverized coal airflow nozzle 12, a dilute pulverized coal airflow nozzle 11, a main circulating flue gas nozzle 18, an external circulating flue gas nozzle 10 and a secondary air nozzle 22, the dilute pulverized coal airflow nozzle 11 is arranged on the side close to a water cooling wall, and the dilute coal airflow nozzle 11 is arranged behind the dense pulverized coal airflow nozzle 12, the main circulation flue gas nozzle 18 is arranged on the side, close to the central line of the direct-flow pulverized coal burner, of the thick pulverized coal airflow nozzle 12 and the thin pulverized coal airflow nozzle 11, the secondary air nozzle 22 is arranged on the side, far away from the central line of the direct-flow pulverized coal burner, of the thick pulverized coal airflow nozzle 12 and the thin pulverized coal airflow nozzle 11, the outer circulation flue gas nozzle 10 is arranged on the side, close to the water cooling wall, of the hearth in the width direction, the outer circulation flue gas nozzle 10 is arranged behind the thin pulverized coal airflow nozzle 11, and the thin pulverized coal airflow nozzle 11, the thick pulverized coal airflow nozzle 12, the main circulation flue gas nozzle 18, the outer circulation flue gas nozzle 10 and the secondary air nozzle 22 are communicated with the lower hearth 5.
Further, the direct flow pulverized coal burners are divided into two types, wherein the direct flow pulverized coal combustion near the wing wall 25 side is the lateral direct flow pulverized coal combustion 24, and the direct flow pulverized coal burner located between the lateral direct flow pulverized coal combustion 24 is the middle direct flow pulverized coal combustion 23.
Further, the plurality of once-through pulverized coal burners disposed on the front arch 2 and the rear arch 3 are equally spaced in the width direction of the furnace.
Further, each direct-flow pulverized coal burner further comprises a main circulation flue gas pipe 17 and a first electric air damper 26, the number of main circulation flue gas nozzles 18 in each direct-flow pulverized coal burner is multiple, the main circulation flue gas nozzles 18 are symmetrically arranged on two sides of the central line of the direct-flow pulverized coal burner along the depth direction of the hearth, the upper ends of the main circulation flue gas nozzles 18 are communicated with one end of the main circulation flue gas pipe 17, the other end of the main circulation flue gas pipe 17 is communicated with the hearth outlet 14, the first electric air damper 26 is arranged on the main circulation flue gas pipe 17, the main circulation flue gas is extracted from the hearth outlet 14, the main circulation flue gas accounts for 60% -75% of the total circulation flue gas, and the concentration of the components of the main circulation flue gas is as follows: o is2：1.6％～4.6％；CO：20ppm～250ppm；CO2：13.5％～18％。
Further, every direct current pulverized coal burner still includes extrinsic cycle flue gas pipe 21 and electronic air damper of second 27, extrinsic cycle flue gas spout 10 in every direct current pulverized coal burner is a plurality of, a plurality of extrinsic cycle flue gas spouts 10 are the equidistant side of arranging near the waterwall of a straight line along furnace width direction, a plurality of extrinsic cycle flue gas spouts 10 upper ends all communicate with extrinsic cycle flue gas pipe 21 one end, the other end of extrinsic cycle flue gas pipe 21 communicates with afterbody flue 16 behind the economizer 15, and set up electronic air damper of second 27 on the extrinsic cycle flue gas pipe 21, extrinsic cycle flue gas is extracted in the afterbody flue 16 behind the economizer 15, extrinsic cycle flue gas accounts for 20% -30% of total cycle flue gas, extrinsic cycle flue gas component concentration is: o is2：3％～5.6％；CO：20ppm～200ppm；CO2：13％～17％。
Further, each lateral direct-flow pulverized coal combustion 24 further comprises a boundary circulating flue gas nozzle 19, and the boundary circulating flue gas nozzles 19 are arranged on the outer side of the lateral direct-flow pulverized coal combustion 24 close to the wing wall 25.
Further, each lateral direct-current pulverized coal combustion 24 further comprises a boundary circulating flue gas pipe 20 and a third electric air damper 28, the number of boundary circulating flue gas nozzles 19 in each lateral direct-current pulverized coal combustion 24 is multiple, the boundary circulating flue gas nozzles 19 are arranged in a straight line shape at equal intervals along the depth direction of the hearth, the upper ends of the boundary circulating flue gas nozzles 19 are communicated with one end of the boundary circulating flue gas pipe 20, the other end of the boundary circulating flue gas pipe 20 is communicated with a tail flue 16 behind the economizer 15, the third electric air damper 28 is arranged on the boundary circulating flue gas pipe 20, the boundary circulating flue gas is extracted from the tail flue 16 behind the economizer 15, the boundary circulating flue gas accounts for 5% -10% of the total circulating flue gas, and the component concentration of the boundary circulating flue gas is as follows: o2: 3% -5.6%; CO: 20ppm to 200 ppm; CO 2: 13 to 17 percent.
Further, the total recirculated flue gas includes main circulation flue gas, outer circulation flue gas and boundary circulation flue gas, and the total recirculated flue gas accounts for the ratio of total flue gas: 15 to 20% at 70 to 100% rated electrical load, 10 to 15% at 50 to 70% rated electrical load, and 0 to 10% at 50% or less rated electrical load.
Further, the W flame boiler further comprises a plurality of tertiary air nozzles 8, the outer sides of the front wall 4 and the rear wall 7 of the lower hearth 5 are respectively provided with the plurality of tertiary air nozzles 8 along the width direction of the hearth, the lower ends of the plurality of tertiary air nozzles 8 are communicated with the lower hearth 5, and an included angle between the central line of each tertiary air nozzle 8 and the horizontal plane is 0-45 degrees.
Further, the W flame boiler also comprises a plurality of over-fire air nozzles 13, a plurality of over-fire air nozzles 13 are respectively arranged at the positions, close to the central line 1-1 of the hearth, of the front arch 2 and the rear arch 3 of the lower hearth 5, the lower ends of the over-fire air nozzles 13 are communicated with the lower hearth 5, and the included angle between the central line of each over-fire air nozzle 13 and the horizontal plane is 20-45 degrees.
Compared with the prior art, the invention has the following effects:
1. the invention greatly reduces the NOx emission at the outlet of the hearth:
the main circulation flue gas is a mixture of gas generated after pulverized coal combustion and a small amount of air leakage, the oxygen content is low, the main circulation flue gas is arranged around the concentrated pulverized coal airflow, the oxygen concentration nearby is reduced, the excessive air coefficient on the arch is reduced to 0.70 from 1.03, a high-temperature oxidizing atmosphere is difficult to form, and the NOx generation amount at the initial stage of pulverized coal combustion is remarkably reduced; meanwhile, the air quantity of the circulating flue gas is adjustable, the mixing proportion can be effectively controlled by adjusting the opening of the valve, and the oxygen supply at the initial stage of ignition of the dense coal powder airflow is changed. The circulating flue gas also contains NO, and the NO is pumped out and then is introduced into a hearth, and can perform out-of-phase reduction reaction with coke generated in the furnace to convert the NO into N2, so that the overall NOx emission is reduced.
2. The invention is beneficial to the rapid ignition and stable combustion of the coal powder:
high-temperature (800-1000 ℃) circulating flue gas is arranged around the dense pulverized coal airflow nozzle, and the high-temperature circulating flue gas can heat the dense pulverized coal airflow, so that pulverized coal particles in the dense pulverized coal airflow can quickly absorb heat, catch fire and stably combust.
3. The invention reduces the content of combustible substances in the fly ash:
the W flame boiler mainly uses hard-burning coal such as anthracite, lean coal and the like, has poor burning effect due to the characteristics of the W flame boiler, is difficult to burn completely, and has more unburned carbon in the smoke discharged into the atmosphere. A part of smoke is extracted and is introduced into the furnace again, so that unburned carbon in the smoke can be reburnt, meanwhile, the dense coal dust airflow is heated by adjacent circulating smoke, the coal dust airflow is ignited earlier, the burnout stroke in the furnace is relatively prolonged, the combustion reaction is more thorough, and the content of fly ash combustible substances is reduced, and the boiler efficiency is improved.
4. The invention is beneficial to reducing the thermal deviation of the water-cooled walls of the front wall and the rear wall of the lower hearth and preventing the water-cooled walls from slagging:
arrange in the extrinsic cycle flue gas that is close to front and back wall side and have two effects: (1) the temperature of the water cooling wall is low (250-350 ℃), and the temperature near the water cooling wall can be reduced; (2) the pulverized coal airflow can be blocked from flowing to the water-cooled walls of the front wall and the rear wall, and meanwhile, the oxygen concentration is low, so that the combustion heat release of pulverized coal particles near the water-cooled walls is reduced, and the temperature near the water-cooled walls can also be reduced. The circulating flue gas volume is adjustable, and the coal powder combustion share near the water-cooled wall of the lower hearth at the corresponding position of the combustor can be changed. When the circulating flue gas volume is increased, the low-temperature flue gas volume near the water-cooled wall of the lower hearth at the corresponding position is increased, the combustion share of pulverized coal near the water-cooled wall is reduced, the wall temperature is reduced, and the water-cooled wall is prevented from being over-heated and slagging. The circulating flue gas amount corresponding to each combustor arranged along the width direction of the hearth is adjusted in a matching manner, so that the wall temperature deviation of the water-cooled wall can be adjusted, and the water-cooled wall fins are prevented from being pulled apart. A group of low-temperature boundary circulating flue gas nozzles are additionally arranged on the outer side of the combustor nozzle close to the side of the wing wall, so that slag bonding of the water-cooled wall of the wing wall is prevented.
Drawings
FIG. 1 is a schematic view of a hearth structure and a flow field of a longitudinal section of the hearth of the invention (in the figure, the flow field distribution of a lower hearth 5 is distributed by taking a hearth center line 1-1 as a symmetrical plane, and the direction of the air flow is marked by an arrow in the figure);
FIG. 2 is a schematic view of the jet-over-arch arrangement of the present invention;
FIG. 3 is a schematic view (section A-A in FIG. 2) of the main cycle flue gas duct 17 and its electrically operated damper 26 of the present invention;
FIG. 4 is a schematic view (section B-B in FIG. 2) of the outer circulation flue gas duct 21 and its electrically operated damper 27 of the present invention;
figure 5 is a schematic view of the boundary loop flue gas duct 19 of the present invention and its electrically operated damper 28 (section C-C in figure 2).
Detailed Description
The first embodiment is as follows: the present embodiment is described with reference to fig. 1 and 2, and the W-flame boiler of the present embodiment using a circulating flue gas type slit direct current pulverized coal burner includes an upper furnace 1 and a lower furnace 5, the lower furnace 5 includes a front arch 2, a rear arch 3, a front wall 4, a rear wall 7, a soot cooling hopper 6, and a plurality of direct current pulverized coal burners, the direct current pulverized coal burners are circulating flue gas type slit direct current pulverized coal burners, the plurality of direct current pulverized coal burners are symmetrically arranged on the front arch 2 and the rear arch 3 with a furnace center line 1-1 as a center, and the plurality of direct current pulverized coal burners are all communicated with the lower furnace 5, each direct current pulverized coal burner includes a dense gas flow pulverized coal nozzle 12, a dilute gas flow nozzle 11, a main circulation flue gas nozzle 18, an outer circulation flue gas nozzle 10, and a secondary air nozzle 22, the dilute gas flow nozzle 11 is arranged on a side close to a water cooling wall, and the dilute gas flow nozzle 11 is arranged behind the dense gas flow nozzle 12, the main circulation flue gas nozzle 18 is arranged on the side, close to the central line of the direct-flow pulverized coal burner, of the thick pulverized coal airflow nozzle 12 and the thin pulverized coal airflow nozzle 11, the secondary air nozzle 22 is arranged on the side, far away from the central line of the direct-flow pulverized coal burner, of the thick pulverized coal airflow nozzle 12 and the thin pulverized coal airflow nozzle 11, the outer circulation flue gas nozzle 10 is arranged on the side, close to the water cooling wall, of the hearth in the width direction, the outer circulation flue gas nozzle 10 is arranged behind the thin pulverized coal airflow nozzle 11, and the thin pulverized coal airflow nozzle 11, the thick pulverized coal airflow nozzle 12, the main circulation flue gas nozzle 18, the outer circulation flue gas nozzle 10 and the secondary air nozzle 22 are communicated with the lower hearth 5.
The concentrated coal powder airflow of the embodiment is sprayed into the lower hearth 5 through a plurality of concentrated coal powder airflow nozzles 12. The secondary air is sprayed into the lower hearth 5 through a plurality of secondary air nozzles 22. The light coal powder airflow is sprayed into the lower hearth 5 through a plurality of light coal powder airflow nozzles 11.
The second embodiment is as follows: referring to fig. 1 and 2, the present embodiment will be described, and the once-through pulverized coal burners of the present embodiment are classified into two types, in which the once-through pulverized coal burners near the wing walls 25 are the side once-through pulverized coal burners 24, and the once-through pulverized coal burners between the side once-through pulverized coal burners 24 are the middle once-through pulverized coal burners 23.
So set up, the difference of lateral part direct current buggy burning 24 and middle part direct current buggy burning 23 lies in, and lateral part direct current buggy burning 24 is close to the outside of wing wall 25, has arranged boundary circulation flue gas spout 19, can prevent that the buggy air current from erodeing the water-cooled wall of wing wall 25. Other components and connections are the same as in the first embodiment.
The third concrete implementation mode: the present embodiment is described with reference to fig. 2, and the plurality of once-through pulverized coal burners disposed in the front arch 2 and the rear arch 3 of the present embodiment are equally spaced in the furnace width direction.
So set up, guarantee through the even and comprehensive gas of direct current pulverized coal burner entering in furnace 5 down. Other compositions and connections are the same as in the first or second embodiments.
The fourth concrete implementation mode: the embodiment is described with reference to fig. 1 to 3, each straight-flow pulverized coal burner of the embodiment further includes a main circulation flue gas pipe 17 and a first electric damper 26, the main circulation flue gas nozzles 18 in each straight-flow pulverized coal burner are multiple, the multiple main circulation flue gas nozzles 18 are symmetrically arranged on two sides of the center line of the straight-flow pulverized coal burner along the depth direction of the furnace hearth, the upper ends of the multiple main circulation flue gas nozzles 18 are all communicated with one end of the main circulation flue gas pipe 17, and the main circulation flue gas nozzles 18 are all communicated with one end of the main circulation flue gas pipe 17The other end of the circulating flue gas pipe 17 is communicated with the hearth outlet 14, a first electric damper 26 is arranged on the main circulating flue gas pipe 17, the main circulating flue gas is extracted from the hearth outlet 14, the main circulating flue gas accounts for 60% -75% of the total circulating flue gas, and the main circulating flue gas has the following component concentrations: o is2：1.6％～4.6％；CO：20ppm～250ppm；CO2：13.5％～18％。
According to the arrangement, the main circulation flue gas is extracted from the hearth outlet 14, the temperature is high and ranges from 800 ℃ to 1000 ℃, and is sprayed into the lower hearth 5 through the main circulation flue gas nozzles 18, secondary air with high air speed carries thick pulverized coal airflow with low air speed to jet downwards in the lower hearth 5, and the main circulation flue gas with the temperature far higher than that of the thick pulverized coal airflow is mixed into the thick pulverized coal airflow after leaving the nozzles, so that the temperature of the thick pulverized coal is rapidly increased, and the ignition temperature is rapidly reached. The main circulation flue gas volume can be adjusted through the first electric damper 26 according to the actual operation condition of the boiler, and is used for adjusting oxygen supply in the initial stage of ignition of the concentrated pulverized coal gas flow. The temperature of the main circulation flue gas and the ratio of each component in the main circulation flue gas are utilized to fully utilize the main circulation flue gas. Other compositions and connection relationships are the same as in the first, second or third embodiment.
The fifth concrete implementation mode: the embodiment is described with reference to fig. 1, fig. 2 and fig. 4, each straight-flow pulverized coal burner of the embodiment further includes an outer circulation flue gas pipe 21 and a second electric damper 27, a plurality of outer circulation flue gas nozzles 10 in each straight-flow pulverized coal burner are arranged in a straight line shape along the width direction of the furnace hearth at equal intervals on the side close to the water-cooled wall, the upper ends of the plurality of outer circulation flue gas nozzles 10 are all communicated with one end of the outer circulation flue gas pipe 21, the other end of the outer circulation flue gas pipe 21 is communicated with the tail flue 16 behind the economizer 15, the second electric damper 27 is arranged on the outer circulation flue gas pipe 21, the outer circulation flue gas is extracted from the tail flue 16 behind the economizer 15, the outer circulation flue gas accounts for 20% -30% of the total circulation flue gas, and the component concentration of the outer circulation flue gas is: o is2：3％～5.6％；CO：20ppm～200ppm；CO2：13％～17％。
According to the arrangement, the external circulation flue gas is extracted from the tail flue 16 behind the economizer 15, the temperature is low and is 250-350 ℃, the external circulation flue gas is sprayed into the lower hearth 5 through the plurality of external circulation flue gas nozzles 10, the low-temperature external circulation flue gas is close to the water cooled walls of the front wall and the rear wall, on one hand, the dense coal dust airflow and the dilute coal dust airflow are prevented from diffusing to the water cooled walls of the front wall 4 and the rear wall 7 to flush the water cooled walls, on the other hand, the temperature of the area near the water cooled walls is reduced, the low-temperature recirculation flue gas quantity can be adjusted through the second electric adjusting air door 27, and the coal dust combustion share near the water cooled walls of the lower hearth 5 at the corresponding position of the direct-flow coal dust burner can be changed. The temperature of the externally circulated flue gas and the ratio of each component in the externally circulated flue gas are utilized fully. Other compositions and connection relationships are the same as those in the first, second, third or fourth embodiment.
The sixth specific implementation mode: referring to the embodiment described with reference to fig. 1, 2 and 5, each lateral once-through pulverized coal combustion 24 of the embodiment further includes a boundary circulation flue gas nozzle 19, and the boundary circulation flue gas nozzle 19 is disposed outside the lateral once-through pulverized coal combustion 24 near the wing wall 25.
So set up, can prevent that buggy air current from scouring the 25 water-cooled walls of wing wall. Other compositions and connection relationships are the same as in the first, second, third, fourth or fifth embodiment.
The seventh embodiment: the present embodiment is described with reference to fig. 1, fig. 2, and fig. 5, each lateral direct-flow pulverized coal combustion 24 of the present embodiment further includes a boundary circulating flue gas pipe 20 and a third electric damper 28, a plurality of boundary circulating flue gas nozzles 19 in each lateral direct-flow pulverized coal combustion 24 are provided, the plurality of boundary circulating flue gas nozzles 19 are arranged in a line shape at equal intervals along the depth direction of the furnace, the upper ends of the plurality of boundary circulating flue gas nozzles 19 are all communicated with one end of the boundary circulating flue gas pipe 20, the other end of the boundary circulating flue gas pipe 20 is communicated with the tail flue 16 behind the economizer 15, the third electric damper 28 is provided on the boundary circulating flue gas pipe 20, the boundary circulating flue gas is extracted from the tail flue 16 behind the economizer 15, the boundary circulating flue gas accounts for 5% to 10% of the total circulating flue gas, and the concentration of the components of the boundary circulating flue gas is: o2: 3% -5.6%; CO: 20ppm to 200 ppm; CO 2: 13 to 17 percent.
So set up, boundary circulation flue gas is extracted in the afterbody flue 16 behind the economizer 15 equally to spout into in lower furnace 5 by a plurality of boundary circulation flue gas spouts 19, boundary circulation flue gas volume can be adjusted through third electronic air damper 28, can prevent that buggy air current from scouring the water-cooled wall of wing wall 25. The temperature of the boundary circulating flue gas and the ratio of each component in the boundary circulating flue gas are utilized to fully utilize the boundary circulating flue gas. Other compositions and connection relationships are the same as in the first, second, third, fourth, fifth or sixth embodiment.
The specific implementation mode is eight: the total recirculated flue gas of this embodiment includes main circulation flue gas, extrinsic cycle flue gas and boundary circulation flue gas, and the ratio of total recirculated flue gas to total flue gas is: 15 to 20% at 70 to 100% rated electrical load, 10 to 15% at 50 to 70% rated electrical load, and 0 to 10% at 50% or less rated electrical load.
So set up, utilize the ratio of occupation of total recirculated flue gas under different operating modes, carry out make full use of to total recirculated flue gas. Other compositions and connection relationships are the same as those of embodiment one, two, three, four, five, six or seven.
The specific implementation method nine: the present embodiment is described with reference to fig. 1, the W-flame boiler of the present embodiment further includes a plurality of tertiary air nozzles 8, the outer sides of the front wall 4 and the rear wall 7 of the lower furnace 5 are respectively provided with the plurality of tertiary air nozzles 8 along the width direction of the furnace, the lower ends of the plurality of tertiary air nozzles 8 are all communicated with the lower furnace 5, and an included angle between the center line of each tertiary air nozzle 8 and the horizontal plane is 0 ° to 45 °.
According to the arrangement, tertiary air is sprayed into the lower hearth 5 through the plurality of tertiary air nozzles 8, and when secondary air, thick pulverized coal airflow, light pulverized coal airflow, main circulation flue gas and outer circulation flue gas reach the tertiary air nozzle area, the tertiary air with high air speed and an included angle of 0-45 degrees with the horizontal angle further ejects the pulverized coal airflow to move downwards, so that staged combustion is realized. Other compositions and connection relationships are the same as those in the first, second, third, fourth, fifth, sixth, seventh or eighth embodiment.
The detailed implementation mode is ten: the present embodiment is described with reference to fig. 1, the W-flame boiler of the present embodiment further includes a plurality of over-fire air nozzles 13, a plurality of over-fire air nozzles 13 are respectively disposed at positions of the front arch 2 and the rear arch 3 of the lower furnace 5 close to the central line 1-1 of the furnace, lower ends of the plurality of over-fire air nozzles 13 are all communicated with the lower furnace 5, and an included angle between the central line of each of the plurality of over-fire air nozzles 13 and the horizontal plane is 20 ° to 45 °.
According to the arrangement, the over-fire air is introduced into the upper part of the lower hearth 5 through the over-fire air nozzles 13, and after the coal dust airflow is injected downwards through the downward-inclined injected tertiary air under the arch, the coal dust airflow which is deflected upwards and is not burnt to be over-fire is mixed with the downward-inclined injected over-fire air in the upper area of the lower hearth 5. Other compositions and connections are the same as those of the first, second, third, fourth, fifth, sixth, seventh, eighth or ninth embodiments.
Principle of operation
The working principle of a W-flame boiler using a circulating flue gas type slit type once-through pulverized coal burner according to the present invention will be described with reference to FIGS. 1 to 5: the W flame boiler of the invention adopts a circulating smoke type gap type direct-current pulverized coal burner, high-temperature recycled smoke is arranged on the side of a dense pulverized coal airflow nozzle, and low-temperature recycled smoke is arranged on the side close to the front wall, the rear wall and the water cooling wall of the wing wall. The oxygen supply at the initial stage of ignition of the concentrated pulverized coal airflow is changed by adjusting the amount of high-temperature recycled flue gas, so that the generation of NOx is effectively controlled. The high-temperature (800-1000 ℃) recirculated flue gas can heat the thick pulverized coal airflow, and ignition and stable combustion of the thick pulverized coal airflow are facilitated. The coal dust airflow is ignited earlier, the burnout stroke in the furnace is prolonged, and the coal dust burnout is facilitated. Meanwhile, unburned carbon in the circulating flue gas enters the furnace for reburning, and the content of fly ash combustible is reduced. The low-temperature (250-350 ℃) recycled flue gas close to the water cooling walls of the front wall and the rear wall can prevent pulverized coal airflow from flowing to the water cooling walls of the front wall and the rear wall. The low-temperature recycled flue gas volume is adjustable, the pulverized coal combustion share near the water-cooled wall of the lower hearth at the corresponding position of the burner can be changed, the wall temperature of the water-cooled walls of the front wall and the rear wall of the lower hearth is adjusted, and the water-cooled wall is prevented from tube explosion, fin pulling crack and slag bonding.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. The utility model provides an adopt W flame boiler of circulation flue gas type slot formula direct current pulverized coal burner, W flame boiler includes furnace (1) and lower furnace (5), and lower furnace (5) are including preceding arch (2), back arch (3), front wall (4), back wall (7), cold ash bucket (6) and a plurality of direct current pulverized coal burner, its characterized in that: the direct-flow pulverized coal burner is a circulating flue gas type gap direct-flow pulverized coal burner, a plurality of direct-flow pulverized coal burners are symmetrically arranged on a front arch (2) and a rear arch (3) by taking a hearth central line (1-1) as a center, the direct-flow pulverized coal burners are communicated with a lower hearth (5), each direct-flow pulverized coal burner comprises a concentrated pulverized coal airflow nozzle (12), a light pulverized coal airflow nozzle (11), a main circulating flue gas nozzle (18), an outer circulating flue gas nozzle (10) and a secondary air nozzle (22), the light pulverized coal airflow nozzle (11) is arranged on the side close to a water cooling wall, the light pulverized coal airflow nozzle (11) is arranged behind the concentrated pulverized coal airflow nozzle (12), the main circulating flue gas nozzle (18) is arranged on the side, close to the central line of the direct-flow pulverized coal burner, of the concentrated pulverized coal airflow nozzle (12) and the light pulverized coal airflow nozzle (11), and the secondary air nozzle (22) is arranged on the side, far away from the direct-flow pulverized coal burner central line, of the concentrated pulverized coal airflow nozzle (12) and the light pulverized coal airflow nozzle (11) On the side of the center line of the device, an outer circulation flue gas nozzle (10) is arranged on the side close to the water cooling wall along the width direction of the hearth, the outer circulation flue gas nozzle (10) is arranged behind a light coal powder airflow nozzle (11), and the light coal powder airflow nozzle (11), a thick coal powder airflow nozzle (12), a main circulation flue gas nozzle (18), the outer circulation flue gas nozzle (10) and a secondary air nozzle (22) are communicated with the lower hearth (5).
2. The W-flame boiler using circulating-flue gas type slotted once-through pulverized-coal burner as claimed in claim 1, wherein: the direct-flow pulverized coal burner is divided into two types, wherein the direct-flow pulverized coal burner close to the wing wall (25) side is the lateral direct-flow pulverized coal burner (24), and the direct-flow pulverized coal burner positioned between the lateral direct-flow pulverized coal burner (24) is the middle direct-flow pulverized coal burner (23).
3. A W-flame boiler using a circulating-flue gas type slotted once-through pulverized-coal burner as claimed in claim 1 or 2, wherein: the intervals of the plurality of straight-flow pulverized coal burners arranged on the front arch (2) and the rear arch (3) along the width direction of the hearth are equal.
4. A W-flame boiler using a circulating-flue gas type slotted once-through pulverized-coal burner as set forth in claim 3, wherein: every direct current pulverized coal burner still includes main circulation flue gas pipe (17) and first electronic damper (26), main circulation flue gas spout (18) in every direct current pulverized coal burner are a plurality of, a plurality of main circulation flue gas spouts (18) are along furnace degree of depth direction symmetrical arrangement in direct current pulverized coal burner central line both sides, a plurality of main circulation flue gas spout (18) upper end all communicate with main circulation flue gas pipe (17) one end, main circulation flue gas pipe (17) other end and furnace export (14) intercommunication, and set up first electronic damper (26) on main circulation flue gas pipe (17), main circulation flue gas is extracted by furnace export (14) department, main circulation flue gas accounts for 60% -75% of total circulation flue gas, main circulation flue gas component concentration is: o is2：1.6％～4.6％；CO：20ppm～250ppm；CO2：13.5％～18％。
5. The W-flame boiler using circulating-flue gas type slotted once-through pulverized-coal burner as claimed in claim 4, wherein: every direct current pulverized coal burner still includes extrinsic cycle flue gas pipe (21) and electronic air damper of second (27), extrinsic cycle flue gas spout (10) in every direct current pulverized coal burner are a plurality of, a plurality of extrinsic cycle flue gas spouts (10) are the equidistant side of arranging near the water-cooling wall of a straight line along furnace width direction, a plurality of extrinsic cycle flue gas spouts (10) upper end all communicate with extrinsic cycle flue gas pipe (21) one end, the extrinsic cycle flue gas pipe (21) other end communicates with afterbody flue (16) behind economizer (15), and set up electronic air damper of second (27) on extrinsic cycle flue gas pipe (21), the extrinsic cycle flue gas is extracted in afterbody flue (16) behind economizer (15), the extrinsic cycle flue gas accounts for 20% -30% of total cycle flue gas, extrinsic cycle flue gas component concentration is: o is2：3％～5.6％；CO：20ppm～200ppm；CO2：13％～17％。
6. The W-flame boiler using circulating-flue gas type slotted once-through pulverized-coal burner as claimed in claim 5, wherein: each lateral direct-flow pulverized coal combustion (24) further comprises a boundary circulating flue gas nozzle (19), and the boundary circulating flue gas nozzles (19) are arranged on the outer side of the lateral direct-flow pulverized coal combustion (24) close to the wing walls (25).
7. The W-flame boiler using circulating-flue gas type slotted once-through pulverized-coal burner as claimed in claim 6, wherein: every lateral part direct current pulverized coal burning (24) still includes boundary circulation flue gas pipe (20), third electronic air damper (28), boundary circulation flue gas spout (19) in every lateral part direct current pulverized coal burning (24) are a plurality ofly, a plurality of boundary circulation flue gas spouts (19) are the equidistant setting of a font along furnace depth direction, a plurality of boundary circulation flue gas spout (19) upper ends all communicate with boundary circulation flue gas pipe (20) one end, the tail flue (16) intercommunication behind boundary circulation flue gas pipe (20) other end and economizer (15), and set up third electronic air damper (28) on the boundary circulation flue gas pipe (20), boundary circulation flue gas is extracted in tail flue (16) behind economizer (15), boundary circulation flue gas accounts for 5% -10% of total circulation flue gas, boundary circulation flue gas component concentration is: o2: 3% -5.6%; CO: 20ppm to 200 ppm; CO 2: 13 to 17 percent.
8. The W-flame boiler using circulating-flue gas type slotted once-through pulverized-coal burner as claimed in claim 7, wherein: the total recirculated flue gas comprises main recirculated flue gas, outer recirculated flue gas and boundary recirculated flue gas, and the total recirculated flue gas accounts for the ratio of the total flue gas: 15 to 20% at 70 to 100% rated electrical load, 10 to 15% at 50 to 70% rated electrical load, and 0 to 10% at 50% or less rated electrical load.
9. A W-flame boiler using a circulating flue gas type slotted once-through pulverized coal burner as claimed in claim 1 or 8, wherein: w flame boiler still includes a plurality of tertiary air spouts (8), and preceding wall (4) and back wall (7) outside of lower furnace (5) are equipped with a plurality of tertiary air spouts (8) along furnace width direction respectively, and a plurality of tertiary air spouts (8) lower extreme all communicate with lower furnace (5), and the central line of every tertiary air spout (8) is 0 to 45 with the contained angle between the level.
10. A W-flame boiler using a circulating flue gas type slotted once-through pulverized coal burner as claimed in claim 9, wherein: the W flame boiler further comprises a plurality of over-fire air nozzles (13), a plurality of over-fire air nozzles (13) are respectively arranged at positions, close to a hearth central line (1-1), of a front arch (2) and a rear arch (3) of the lower hearth (5), the lower ends of the over-fire air nozzles (13) are communicated with the lower hearth (5), and an included angle between the central line of each over-fire air nozzle (13) and the horizontal plane is 20 degrees to 45 degrees.
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