CN112902148B

CN112902148B - Boiler combustion system

Info

Publication number: CN112902148B
Application number: CN202110086628.8A
Authority: CN
Inventors: 闫飞; 徐书德; 朱继锋; 邵海雷; 辛世伟; 郭恩陶; 陈守磊
Original assignee: Zhejiang Zheneng Zhongmei Zhoushan Coal Power Co ltd
Current assignee: Zhejiang Zheneng Zhongmei Zhoushan Coal Power Co ltd
Priority date: 2021-01-22
Filing date: 2021-01-22
Publication date: 2023-01-17
Anticipated expiration: 2041-01-22
Also published as: CN112902148A

Abstract

The invention relates to a boiler combustion system, which comprises a system body, wherein the system body comprises a hearth, a combustor, an over-fire air bellow positioned above the combustor and a primary air cylinder arranged in the combustor, the over-fire air bellow is communicated with the primary air cylinder through a communicating mechanism, an isolation main valve is arranged on the communicating mechanism, and when the combustor runs, the isolation main valve is in a closed state; when the combustor stops operating, keep apart the main valve and be open mode, when the combustor stops operating, keep apart the main valve and open, the wind in the over fire air bellows will enter into the dryer of once of combustor as the cooling air this moment, play the cooling action to a dryer, regard the wind regime in the over fire air bellows as cooling medium, this wind regime is the boiler classification burning air-used wind of over fire, it is good to the cooling effect of a dryer, can not influence the combustion efficiency of boiler, this scheme has replaced adopting the mode of the dryer of single adjustment secondary amount of wind cooling in the original technology, its used cooling medium is few, and the cooling effect is good.

Description

Boiler combustion system

Technical Field

The invention relates to the technical field of combustion boiler structures, in particular to a boiler combustion system.

Background

The ultra-supercritical front-and-rear wall opposed-flow boiler is generally provided with three layers of front walls and three layers of rear walls, and each layer of the front wall burners and each layer of the rear wall burners are respectively provided with 6 burners or 8 burners. During normal operation, five coal mills are put into operation under load to meet the maximum output of the boiler, and one coal mill is used as a spare coal mill. When the load is more than 70% when the unit operates with variable load, 5 coal mills are put into operation, 4 pulverizing systems are put into operation when the load is more than 40% and less than 70%, 3 pulverizing systems are put into operation when the load is less than 40%, and the specific corresponding load can be properly adjusted. 8 NOx nozzles are respectively arranged on the front wall and the rear wall above the combustor, and 16 NOx nozzles are arranged in total.

The boiler combustion system is generally composed of a low NOx cyclone burner, a NOx nozzle, an open annular large air box and the like. The design of the combustor can ensure the high-efficiency combustion of the pulverized coal and greatly reduce the emission of nitrogen oxides. The function of the burner is to establish a stable ignition point in a proper range outside the burner throat and to achieve complete and efficient combustion of pulverized coal. The arrangement of the burner is not only beneficial to controlling the discharge of NOx, but also can meet the requirement of the retention time in the furnace for the complete combustion of the pulverized coal. The burner makes full use of the characteristic of air staged combustion, the pulverized coal nozzle is positioned in the central area of the burner, the interaction of air/pulverized coal at the root of flame can be effectively controlled, secondary air enters the burner through three annular air channels outside a primary air channel of the burner, the air quantity of the secondary air can be adjusted, a small amount of the secondary air enters a transition area surrounding the periphery of the primary air channel so as to control the oxygen quantity of a fuel-rich area in the center of the flame, which is beneficial to reducing the emission of NOx, an inner secondary air area and an outer secondary air area are sequentially arranged on the outer ring of the transition area, the secondary air can respectively enter the two areas, a rotary secondary air flow is generated through an adjustable axial blade in the burner, the mixing of air and the primary air is controlled, and the generation quantity of NOx is reduced by controlling the combustion rate and the secondary air quantity. The secondary air is gradually mixed with products of initial combustion in the combustion process to complete the burnout of the pulverized coal, so that the generation of NOx is minimized. Among them, the NOx nozzle (also referred to as OFA or staged air nozzle) can further reduce the emission of NOx by shunting a part of the combustion air of the main burner to the NOx nozzle by means of staged air supply. The upper part of the wind box is provided with a baffle plate which separates the secondary air of the burner area from the air supply of the NOx nozzle. The secondary air quantity of the main combustion area and the hot air quantity of the NOx nozzle are respectively controlled by secondary air baffles on two side walls of the air box, and an air measuring device is arranged in front of the baffles to measure the air quantity entering the main combustion area and the NOx nozzle.

This form of boiler exposes a number of problems as boiler efficiency continues to increase and boiler NOx ultra-low emission requirements become higher and higher. For example, the primary air duct of the boiler burner is seriously burnt and damaged, the condition of burning and damage of the primary air duct of the burner commonly exists in the existing ultra-supercritical opposed combustion boiler burner, and the burning and damage of the primary air duct of the burner are mainly related to the reasons of high efficiency of the existing boiler, high central temperature of a hearth (generally 1200-1400 ℃, and 1600 ℃ for high temperature), more heat received by the whole primary air duct and the like. The powder process system that boiler burner corresponds is put into operation, the medium that flows through in the dryer once is the wind powder mixture, wind powder mixture temperature is about 70 ~ 90 ℃, the dryer outside once is the combustor overgrate air, the temperature is about 300 ℃, in the dryer once of combustor when throwing the use corresponding to the powder process system, outer wind can play good cooling effect to the dryer once of combustor, a dryer material itself has fine heat resistance, under this kind of condition, a dryer can guarantee long-term steady operation, can not warp. However, when the pulverizing system corresponding to the burner is stopped, the cooling medium is lost in the corresponding primary air duct, and meanwhile, the flame of the adjacent layer or the opposite wall burner tends to the nozzle of the burner, and meanwhile, the tempering condition also exists, so that the temperature of the nozzle is increased. Under the superposition of double-layer adverse factors of loss of cooling medium and increase of the temperature of the nozzle, the temperature of a primary air barrel of the combustor can be rapidly increased to over 900 ℃. From the actual burning situation at present, the ultra-supercritical boiler is generally burnt in the middle-upper layer burner at present, wherein the upper layer burner is particularly serious, and the burning is serious every year and needs to be replaced.

Disclosure of Invention

The invention aims to solve the technical problem of providing a boiler combustion system which can cool a primary air duct, has a good cooling effect and can avoid burning loss of the primary air duct.

The technical scheme adopted by the invention is that the boiler combustion system comprises a system body, wherein the system body comprises a hearth, a combustor, an over-fire air box positioned above the combustor and a primary air cylinder arranged in the combustor, the over-fire air box is communicated with the primary air cylinder through a communicating mechanism, an isolation main valve is arranged on the communicating mechanism, and when the combustor runs, the isolation main valve is in a closed state; when the burner is shut down, the isolation main valve is in an open state.

The invention has the beneficial effects that: adopt the boiler combustion system of above-mentioned structure, with the overfire air bellows and a dryer intercommunication, when the combustor is shut down, keep apart the main valve and open, the wind in the overfire air bellows will enter into the dryer of a dryer of combustor as the cooling air this moment, play the cooling action to a dryer, regard the wind regime in the overfire air bellows as cooling medium, this wind regime is the boiler fractional combustion overfire air with wind, it is good to the cooling effect of a dryer, and after entering furnace, can not influence the combustion efficiency of boiler, this scheme has replaced the mode that adopts single adjustment secondary amount of wind cooling dryer in the original technique, its used cooling medium is few, and the cooling effect is good.

As prior, the system body still includes the wind powder pipe of once with a dryer intercommunication, feed mechanism one end and burn out air bellows intercommunication, the other end and the wind powder pipe intercommunication of once, adopt this structure, link together feed mechanism and the wind powder union coupling of once, be convenient for supply air in the dryer of once, make things convenient for boiler structural design overall arrangement, through feed mechanism with burn out air bellows and the wind powder pipe intercommunication of once, when keeping apart the main valve and opening, the wind in the burn out air bellows will enter into the wind powder pipe as the cooling air, and enter into the dryer of combustor once through the wind powder pipe, play the cooling effect to a dryer, its used coolant is few, and the cooling effect is good.

As the priority, the feed mechanism includes the main cooling pipe that communicates with the burn-up air bellows and the vice cooling pipe that one end and main cooling pipe intercommunication other end and the first wind powder pipe intercommunication, vice cooling pipe is located the first wind powder pipe directly over, adopt this structure, when keeping apart the main valve and opening, the wind in the burn-up air bellows will enter into main cooling pipe as the cooling air, flow to vice cooling pipe again, because vice cooling pipe is located the first wind powder pipe directly over, the cooling air that vice cooling pipe flows in the wind powder pipe will play a scouring action to the first wind powder pipe so, avoid the phenomenon of long-pending powder to appear in the junction of first wind powder pipe and vice cooling pipe, and this structure also is favorable to the cooling air source to enter into the first wind pipe and cool off the first wind pipe, the cooling effect is good.

As prior, vice cooling tube includes vice pipe body and slope pipe, the one end and the main cooling tube intercommunication of vice pipe body, the other end and slope pipe intercommunication, slope pipe one end and vice pipe body intercommunication, the other end and a wind powder pipe intercommunication, vice pipe body and slope pipe all are located a wind powder pipe directly over, the slope pipe inclines towards a wind powder pipe direction, adopt this structure, the cooling air that comes out from the slope pipe can play a scouring action to a wind powder pipe, avoid a wind powder pipe and the junction of slope pipe phenomenon of long-pending powder to appear, the slope pipe inclines towards a wind powder pipe direction, can avoid a wind powder pipe and the junction of slope pipe to be worn and torn by the buggy.

Preferably, the auxiliary cooling pipe further comprises a cooling air adjusting valve arranged on the inclined pipe, the cooling air adjusting valve can adjust the flow of cooling air, and powder accumulation in the inclined pipe can be avoided.

Preferably, the included angle α between the inclined tube and the primary air powder tube is in the range: alpha is more than or equal to 30 degrees and less than or equal to 45 degrees, and by adopting the structure, cooling air coming out of the inclined pipe can better play a role of scouring the primary air-powder pipe, so that the phenomenon of powder accumulation at the joint of the primary air-powder pipe and the inclined pipe is avoided, and the joint of the primary air-powder pipe and the inclined pipe is better prevented from being abraded by pulverized coal.

As the priority, the auxiliary pipe body is horizontal structure, and main cooling pipe is the right angle structure, adopts this structure, horizontal structure's auxiliary pipe body for the cooling air that enters into the auxiliary pipe body also is the horizontal flow, and during the inclined pipe of slope structure was gone into to the horizontally cooling air, at last rushed into the air powder pipe, can avoid appearing the phenomenon of long-pending powder in the inclined pipe and the air powder pipe, and the main cooling pipe of right angle structure helps the cooling air motion, improves cooling efficiency.

As the precedence, the inside of the junction of the inclined pipe and the primary air-powder pipe adopts a lining ceramic structure, and by adopting the structure, the junction of the primary air-powder pipe and the inclined pipe can be prevented from being worn by coal powder.

As the priority, the system body still includes the three-phase expansion joint of setting between a wind powder pipe and an dryer, three-phase expansion joint one end and a wind powder pipe intercommunication, and the other end and a dryer intercommunication adopt this structure, and the cooling air that comes out from a wind powder pipe advances the three-phase expansion joint, finally enters into an dryer and cools off a dryer, avoids a dryer to be burnt and damaged.

As a priority, the burner includes the upper burner, middle level combustor and lower floor's combustor, the primary air powder pipe includes the upper air powder pipe with upper burner intercommunication, the middle level air powder pipe with middle level combustor intercommunication and the lower floor's air powder pipe with lower floor's combustor intercommunication, the dip pipe includes the upper inclined tube with upper air powder pipe intercommunication, the middle level dip pipe with middle level air powder pipe intercommunication and the lower floor's dip pipe with lower floor's air powder pipe intercommunication, the auxiliary pipe body includes the upper auxiliary pipe body with upper inclined tube intercommunication, the middle level auxiliary pipe body with middle level dip pipe intercommunication and the lower floor's auxiliary pipe body with lower floor's dip pipe intercommunication, cooling air regulating valve is including setting up the upper cooling air governing valve on the upper inclined tube, the middle level cooling air governing valve that sets up on the middle level dip pipe, the lower floor's cooling air governing valve that sets up on the lower floor's dip pipe, adopt this structure, the combustor adopts the mode of hierarchical burning, the primary air in the boiler system that will adopt the mode of burning is as the dryer that cools off, carry out the primary air cooling air dryer that the effect is gone into as the best, avoid burning loss of each time.

Drawings

FIG. 1 is a schematic structural view of a boiler combustion system according to the present invention;

FIG. 2 is an enlarged view taken at A in FIG. 1;

as shown in the figure: 1. a hearth; 2. a burner; 3. an over-fire air bellow; 4. a primary air duct; 5. a communication mechanism; 6. an isolation main valve; 7. a primary air powder pipe; 8. a primary cooling tube; 9. a secondary cooling tube; 10. a secondary pipe body; 11. an inclined tube; 12. a cooling air regulating valve; 13. a three-phase expansion joint; 14. an upper burner; 15. a middle layer burner; 16. a lower burner; 17. an upper layer wind powder pipe; 18. a middle layer wind powder pipe; 19. a lower layer wind powder pipe; 20. an upper layer auxiliary pipe body; 21. a middle layer auxiliary pipe body; 22. a lower auxiliary pipe body; 23. an upper layer cooling air regulating valve; 24. a middle layer cooling air regulating valve; 25. and a lower layer cooling air regulating valve.

Detailed Description

The invention is further described below with reference to the accompanying drawings in combination with specific embodiments so that those skilled in the art can practice the invention with reference to the description, and the scope of the invention is not limited to the specific embodiments.

It will be understood by those skilled in the art that in the present disclosure, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for convenience in describing the invention and simplicity in description, but do not indicate or imply that the device or element so referred to must have a particular orientation, be constructed in a particular orientation, and be constructed in a particular manner of operation, and thus, the terms are not to be construed as limiting the invention.

Example 1:

the embodiment relates to a boiler combustion system, which comprises a system body, as shown in fig. 1 and fig. 2, the system body comprises a hearth 1, a burner 2, an over-fire air box 3 positioned above the burner 2 and a primary air barrel 4 arranged in the burner 2, the over-fire air box 3 is communicated with the primary air barrel 4 through a communicating mechanism 5, an isolation main valve 6 is arranged on the communicating mechanism 5, and when the burner 2 operates, the isolation main valve 6 is in a closed state; when the burner 2 is shut down, the isolation main valve 6 is open. Like the boiler combustion system of structure in fig. 1, with the overfire air bellows 3 and dryer 4 intercommunication once, when combustor 2 is shut down, keep apart main valve 6 and open, the overfire air in the overfire air bellows 3 will enter into dryer 4 once of combustor 2 as the cooling air this moment, play the cooling action to dryer 4 once, regard the wind regime in the overfire air bellows 3 as cooling medium, this wind regime is for boiler level burning air, its cooling effect to dryer 4 is good once, the temperature range of this wind regime is: 300-340 ℃, and the pressure range is as follows: 0.3 kpa-1.5 kpa, namely, the secondary air is close to the secondary air in the boiler, after the air source enters the hearth 1, the combustion efficiency of the boiler cannot be influenced, the scheme replaces the mode of singly adjusting the secondary air quantity to cool the primary air duct 4 in the prior art, the used cooling medium is less, and the cooling effect is good.

The system body further comprises a distributor and three-phase expansion joints 13, the distributor is arranged between the primary air powder pipe 7 and the primary air cylinder 4 and is divided into two parts, the two three-phase expansion joints 13 are connected with the distributor respectively, each three-phase expansion joint 13 is correspondingly connected with the primary air cylinder 4 of one combustor 2, the structure is adopted, cooling air coming out of the primary air powder pipe 7 enters the three-phase expansion joints 13 and finally enters the primary air cylinder 4 to cool the primary air cylinder 4, and the primary air cylinder 4 is prevented from being burnt.

Example 2:

the embodiment relates to a boiler combustion system, which comprises a system body, as shown in fig. 1, the system body comprises a hearth 1, a combustor 2, an over-fire air bellows 3 positioned above the combustor 2, a primary air duct 4 arranged in the combustor 2 and a primary air powder pipe 7 communicated with the primary air duct 4, the over-fire air bellows 3 is communicated with the primary air powder pipe 7 through a communicating mechanism 5, one end of the communicating mechanism 5 is communicated with the over-fire air bellows 3, the other end of the communicating mechanism is communicated with the primary air powder pipe 7, an isolation main valve 6 is arranged on the communicating mechanism 5, and when the combustor 2 operates, the isolation main valve 6 is in a closed state; when the burner 2 is shut down, the isolation main valve 6 is open. Like the boiler combustion system of structure in fig. 1, adopt this structure, link together feed mechanism 5 and a wind powder pipe 7, be convenient for toward supplying air in dryer 4, make things convenient for the boiler structural design overall arrangement, will burn out wind bellows 3 and a wind powder pipe 7 intercommunication through feed mechanism 5, when keeping apart main valve 6 and opening, the wind in the burn out wind bellows 3 will enter into the wind powder pipe as the cooling air, and enter into a dryer 4 of combustor 2 through the wind powder pipe in, play the cooling action to a dryer 4, its used coolant is few, and the cooling effect is good.

Further, the communicating mechanism 5 comprises a main cooling pipe 8 communicated with the over-fire air bellow 3 and an auxiliary cooling pipe 9, one end of the auxiliary cooling pipe 9 is communicated with the main cooling pipe 8, the other end of the auxiliary cooling pipe 9 is communicated with the primary air powder pipe 7, the auxiliary cooling pipe 9 is located right above the primary air powder pipe 7, by adopting the structure, when the isolation main valve 6 is opened, air in the over-fire air bellow 3 can enter the main cooling pipe 8 as cooling air and then flows to the auxiliary cooling pipe 9, because the auxiliary cooling pipe 9 is located right above the primary air powder pipe 7, the cooling air flowing into the air powder pipe from the auxiliary cooling pipe 9 can play a scouring role on the primary air powder pipe 7, the phenomenon of powder accumulation at the joint of the primary air powder pipe 7 and the auxiliary cooling pipe 9 is avoided, and the structure is also favorable for enabling a cooling air source to enter the primary air barrel 4 to cool the primary air barrel 4, and the cooling effect is good.

Further, the auxiliary cooling pipe 9 comprises an auxiliary pipe body 10 and an inclined pipe 11, one end of the auxiliary pipe body 10 is communicated with the main cooling pipe 8, the other end of the auxiliary pipe body is communicated with the inclined pipe 11, one end of the inclined pipe 11 is communicated with the auxiliary pipe body 10, the other end of the inclined pipe is communicated with the primary air powder pipe 7, the auxiliary pipe body 10 and the inclined pipe 11 are both located right above the primary air powder pipe 7, the inclined pipe 11 inclines towards the primary air powder pipe 7, by adopting the structure, the cooling air coming out of the inclined pipe 11 can play a scouring role on the primary air powder pipe 7, the phenomenon that powder is accumulated at the joint of the primary air powder pipe 7 and the inclined pipe 11 is avoided, the inclined pipe 11 inclines towards the primary air powder pipe 7, and the joint of the primary air powder pipe 7 and the inclined pipe 11 can be prevented from being abraded by pulverized coal.

Furthermore, the auxiliary cooling pipe 9 further comprises a cooling air adjusting valve 12 arranged on the inclined pipe 11, and the cooling air adjusting valve 12 can adjust the flow of cooling air and avoid powder accumulation in the inclined pipe 11.

Further, the range of the included angle alpha between the inclined pipe 11 and the primary air powder pipe 7 is as follows: alpha is more than or equal to 30 degrees and less than or equal to 45 degrees, and by adopting the structure, the cooling air coming out of the inclined pipe 11 can better play a role of scouring the primary air-powder pipe 7, so that the phenomenon of powder accumulation at the joint of the primary air-powder pipe 7 and the inclined pipe 11 is avoided, and the joint of the primary air-powder pipe 7 and the inclined pipe 11 is better prevented from being abraded by pulverized coal.

Further, the auxiliary pipe body 10 is horizontal structure, and main cooling pipe 8 is the right angle structure, adopts this structure, horizontal structure's auxiliary pipe body 10 for the cooling air that enters into auxiliary pipe body 10 also is the horizontal flow, and during the horizontal cooling air rushed into inclined pipe 11 of inclined structure, rushed into air powder pipe 7 at last, can avoid appearing the phenomenon of long-pending powder in inclined pipe 11 and air powder pipe 7, and main cooling pipe 8 of right angle structure helped the cooling air motion, improved cooling efficiency.

Furthermore, the inside of the joint of the inclined pipe 11 and the primary air-powder pipe 7 adopts a lining ceramic structure, and by adopting the structure, the joint of the primary air-powder pipe 7 and the inclined pipe 11 can be prevented from being worn by coal powder.

Example 3:

the invention relates to a boiler combustion system, including the system body, as shown in fig. 1, the system body includes the burner 1, burner 2, the burn-up air bellows 3 located above burner 2, set up in primary dryer 4 and primary air powder tube 7 communicated with primary dryer 4 in burner 2, burner 2 includes upper burner 14, middle burner 15 and lower burner 16, primary dryer 4 includes upper primary dryer 4 set up in upper burner 14, middle layer primary dryer 4 set up in middle burner 15 and lower layer primary dryer 4 set up in lower burner 16, primary air powder tube 7 includes upper air powder tube 17 communicated with upper burner 14, middle layer air powder tube 18 communicated with middle burner 15 and lower layer air powder tube 19 communicated with lower burner 16, burn-up air bellows 3 and upper layer air powder tube 17, middle layer air powder tube 18 and lower layer air powder tube 19 communicated through the communicating mechanism 5, one end of burn-up air bellows 5 communicates with middle layer air powder tube 3, another end of the other end of the air powder tube 3 and lower layer air powder tube 6 separately, there are a total air powder valve for isolating when the burner is operated, the upper air powder tube 6 is a total air duct 6 and isolating valve for isolating; when the burner 2 is shut down, the isolating main valve 6 is open.

Boiler combustion system as structure in fig. 1, with the overfire air bellows 3 and an dryer 4 intercommunication, when combustor 2 is shut down, keep apart the main valve 6 and open, the overfire air in the overfire air bellows 3 will enter into an dryer 4 of combustor 2 as the cooling air this moment, play the cooling action to an dryer 4, regard the wind regime in the overfire air bellows 3 as cooling medium, this wind regime is for boiler level burning air, its cooling effect to an dryer 4 is good, the temperature range of this wind regime is: 300-340 ℃, and the pressure range is as follows: 0.3 kpa-1.5 kpa, namely, the secondary air is close to the secondary air in the boiler, after the air source enters the hearth 1, the combustion efficiency of the boiler cannot be influenced, the scheme replaces the mode of singly adjusting the secondary air quantity to cool the primary air duct 4 in the prior art, the used cooling medium is less, and the cooling effect is good.

Further, the communicating mechanism 5 comprises a main cooling pipe 8 communicated with the over-fire air bellows 3 and an auxiliary cooling pipe 9, one end of the auxiliary cooling pipe 9 is communicated with the main cooling pipe 8, the other end of the auxiliary cooling pipe is communicated with the primary air powder pipe 7, the auxiliary cooling pipe 9 is positioned right above the primary air powder pipe 7, by adopting the structure, when the isolation main valve 6 is opened, air in the over-fire air bellows 3 can enter the main cooling pipe 8 as cooling air and then flows to the auxiliary cooling pipe 9, because the auxiliary cooling pipe 9 is positioned right above the primary air powder pipe 7, the cooling air flowing into the air powder pipe from the auxiliary cooling pipe 9 can play a scouring role on the primary air powder pipe 7, the phenomenon of powder accumulation at the joint of the primary air powder pipe 7 and the auxiliary cooling pipe 9 is avoided, and the structure is also beneficial to the fact that a cooling air source enters the primary air duct 4 to cool the primary air duct 4, and the cooling effect is good.

Further, the auxiliary cooling pipe 9 includes an auxiliary pipe body 10 and an inclined pipe 11, the inclined pipe 11 includes an upper inclined pipe communicated with the upper layer wind powder pipe 17, a middle layer inclined pipe communicated with the middle layer wind powder pipe 18 and a lower inclined pipe communicated with the lower layer wind powder pipe 19, the auxiliary pipe body 10 includes an upper auxiliary pipe body 20 communicated with the upper inclined pipe, a middle layer auxiliary pipe body 21 communicated with the middle layer inclined pipe and an auxiliary pipe body 10 communicated with the lower inclined pipe, the upper auxiliary pipe body 20 and the upper inclined pipe are both located right above the upper layer wind powder pipe 17, the middle layer auxiliary pipe body 21 and the middle layer inclined pipe are both located right above the middle layer wind powder pipe 18, the lower auxiliary pipe body 22 and the lower inclined pipe are both located right above the lower layer wind powder pipe 19, the upper inclined pipe is inclined towards the upper layer wind powder pipe 17, the middle layer inclined pipe is inclined towards the middle layer wind powder pipe 18, and the lower layer inclined pipe is inclined towards the lower layer wind powder pipe 19. By adopting the structure, the cooling air coming out of the inclined pipe can play a role of scouring the primary air powder pipe 7, the phenomenon of powder accumulation at the joint of the primary air powder pipe 7 and the inclined pipe is avoided, the inclined pipe 11 inclines towards the primary air powder pipe 7, and the joint of the primary air powder pipe 7 and the inclined pipe can be prevented from being abraded by pulverized coal.

Furthermore, an upper-layer cooling air adjusting valve 23 is arranged on the upper-layer inclined pipe, a middle-layer cooling air adjusting valve 24 is arranged on the middle-layer inclined pipe, a lower-layer cooling air adjusting valve 12 is arranged on the lower-layer inclined pipe, the cooling air adjusting valve 12 corresponding to each layer can adjust the flow of cooling air, and powder accumulation in the corresponding inclined pipe 11 can be avoided.

Further, the range of the included angle alpha between the upper-layer inclined pipe and the upper-layer wind powder pipe 17 is as follows: alpha is more than or equal to 30 degrees and less than or equal to 45 degrees, and the value range of the included angle alpha between the middle-layer inclined pipe and the middle-layer wind powder pipe 18 is as follows: alpha is more than or equal to 30 degrees and less than or equal to 45 degrees, and the value range of the included angle alpha between the lower inclined pipe and the lower wind powder pipe 19 is as follows: alpha is more than or equal to 30 degrees and less than or equal to 45 degrees, and by adopting the structure, the cooling air coming out of the inclined pipe 11 can better play a role of scouring the primary air powder pipe 7, so that the phenomenon of powder accumulation at the joint of the primary air powder pipe 7 and the inclined pipe 11 is avoided, and the joint of the primary air powder pipe 7 and the inclined pipe 11 is better prevented from being abraded by pulverized coal.

Further, upper auxiliary pipe body 20, middle level auxiliary pipe body 21 and lower floor's auxiliary pipe body 22 are horizontal structure, main cooling pipe 8 is the right angle structure, adopt this structure, horizontal structure's auxiliary pipe body 10, make the cooling air that enters into auxiliary pipe body 10 also be the horizontal flow, during the inclined pipe 11 of slope structure is gone into to horizontally cooling air, at last in rushing into the wind powder pipe 7, can avoid appearing the phenomenon of long-pending powder in the inclined pipe 11 and the wind powder pipe 7, the main cooling pipe 8 of right angle structure helps the cooling air motion, and the cooling efficiency is improved.

Further, the inside of the junction of the upper inclined pipe and the upper wind powder pipe 17 adopts a ceramic lining structure, the inside of the junction of the middle inclined pipe and the middle wind powder pipe 18 adopts a ceramic lining structure, and the inside of the junction of the lower inclined pipe and the lower wind powder pipe 19 adopts a ceramic lining structure, so that the junction of the primary wind powder pipe 7 and the inclined pipe 11 can be prevented from being worn by pulverized coal by adopting the structure.

The primary air duct 4 is visually represented by burning loss: the nozzle becomes oval, blackens, embrittles, thins and even falls off: after a period of high load operation. The occurrence position is as follows: it is seen as the primary air duct 4 nozzle of several burners 2 in the middle of the upper burner 14. Pre-signs occurred: the wall temperature thermocouple of the 2-nozzle of the burner measures that the shutdown wall temperature of the powder-making system is high, the startup wall temperature of the powder-making system is reduced, the high temperature and the low temperature are frequently alternated, the wall temperature rapidly rises to above the allowable temperature after shutdown, and no cooling effect is caused by introducing secondary air.

Claims

1. A boiler combustion system, includes the system body, its characterized in that: the system body comprises a hearth (1), a combustor (2), an over-fire air box (3) positioned above the combustor (2) and a primary air barrel (4) arranged in the combustor (2), wherein the over-fire air box (3) is communicated with the primary air barrel (4) through a communicating mechanism (5), an isolation main valve (6) is arranged on the communicating mechanism (5), and when the combustor (2) operates, the isolation main valve (6) is in a closed state; when the combustor (2) stops running, the isolation main valve (6) is in an open state; the system body also comprises a primary air powder pipe (7) communicated with the primary air duct (4), one end of the communicating mechanism (5) is communicated with the over-fire air bellows (3), and the other end is communicated with the primary air powder pipe (7); the communicating mechanism (5) comprises a main cooling pipe (8) communicated with the over-fire air bellow (3) and an auxiliary cooling pipe (9) with one end communicated with the main cooling pipe (8) and the other end communicated with the primary air powder pipe (7), and the auxiliary cooling pipe (9) is positioned above the primary air powder pipe (7); the auxiliary cooling pipe (9) comprises an auxiliary pipe body (10) and an inclined pipe (11), one end of the auxiliary pipe body (10) is communicated with the main cooling pipe (8), the other end of the auxiliary pipe body is communicated with the inclined pipe (11), one end of the inclined pipe (11) is communicated with the auxiliary pipe body (10), the other end of the inclined pipe (11) is communicated with the primary air powder pipe (7), and the auxiliary pipe body (10) and the inclined pipe (11) are both positioned above the primary air powder pipe (7); the auxiliary cooling pipe (9) further comprises a cooling air adjusting valve (12) arranged on the inclined pipe (11).

2. A boiler combustion system according to claim 1, characterized in that: the range of the included angle alpha between the inclined pipe (11) and the primary air powder pipe (7) is as follows: alpha is more than or equal to 30 degrees and less than or equal to 45 degrees.

3. A boiler combustion system as claimed in claim 1, characterized in that: the auxiliary pipe body (10) is of a horizontal structure.

4. A boiler combustion system according to claim 1, characterized in that: the inner part of the joint of the inclined pipe (11) and the primary air powder pipe (7) adopts a lining ceramic structure.

5. A boiler combustion system as claimed in claim 1, characterized in that: the burner (2) comprises an upper layer burner (14), a middle layer burner (15) and a lower layer burner (16).

6. A boiler combustion system according to claim 5, characterized in that: the primary air powder pipe (7) comprises an upper air powder pipe (17) communicated with an upper burner (14), a middle air powder pipe (18) communicated with a middle burner (15) and a lower air powder pipe (19) communicated with a lower burner (16), the auxiliary pipe body (10) comprises an upper auxiliary pipe body (20) communicated with an upper inclined pipe, a middle auxiliary pipe body (21) communicated with a middle inclined pipe and a lower auxiliary pipe body (22) communicated with a lower inclined pipe, and the cooling air regulating valve (12) comprises an upper cooling air regulating valve (23) arranged on the upper inclined pipe, a middle cooling air regulating valve (24) arranged on the middle inclined pipe and a lower cooling air regulating valve (25) arranged on the lower inclined pipe.