CN1118856A

CN1118856A - Concentrated coal powder straight flow burner

Info

Publication number: CN1118856A
Application number: CN 94115573
Authority: CN
Inventors: 徐秀清; 曾瑞良
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 1994-09-16
Filing date: 1994-09-16
Publication date: 1996-03-20
Anticipated expiration: 2014-09-16
Also published as: CN1060855C

Abstract

The burner features that the elbow differential concentration separator with hollow flow distribution plate and double head screw guide dome with hollow core pipe are used, and two working systems (with preheated nozzle or without it) are designed according to the coal grade. it has better performance for concentrating coal powder, collects more than 90% coal powder in primary wind pipe to the outside of the elbow, the 180 deg. guide flow capacity is near 100%, thus effectively improving the combustion stability during light load oil cut-off and reducing NOx exhaust.

Description

Concentrated coal powder straight flow burner

The invention belongs to the combustion apparatus technical field, relate to a kind of coal powder direct supplying burner, particularly relate to a kind of pulverized coal bias combustion device of four jiaos of arranged tangential.

In the prior art, for generating plant pulverized coal boiler, especially the pulverized-coal fired boiler of four jiaos of arranged tangential, realize that dense-dilute burner combustion technology (being rich or poor combustion technology) has received the concern of domestic and international relevant department, it is acknowledged as and solves steady combustion in the stove, realizes underload oil-break peak regulation, low NOx combustion prevents ash erosion, and the better approach that improves coal adaptability.Dense-dilute burner combustion technology is that the breeze airflow in airduct is divided into deep or light two strands, and dense one sent into the side of waring oneself in front of a fire of corner firing; Its mechanism is to make local formation " advantage of catching fire will rapidly obtain high-temperature flue gas after the coal dust (being Fu Fenliu) that is about to high concentration will be injected burner hearth, make it to be heated to ignition temperature; Combustion zone after catching fire then replenishes enough oxygen by the light powder stream of higher oxygen concentration, also in the burning that is beneficial to after catching fire.As seen, improve the coal powder density of rich powder stream and, then be the key point that realizes dense-dilute burner combustion technology effectively with the side of waring oneself in front of a fire of rich powder conductance to corner firing.

At present in the prior art developmental research go out some shade burners, for example the Chinese utility model patent of application on January 14th, 89 " variation coal powder density burner " (notification number: CN 2046975U) and the patent of invention " coal powder burner " (publication number CN1076261A) of application on June 2nd, 92 be exactly to develop according to the mechanism of above-mentioned bias combustion.This type of shade burner is because only by the centrifugation of an airduct elbow, thus make deep or light two strands of air-flows to contain powder concentration difference little, (dense side about 65%, light side about 35%), so the effect of bias combustion goes out relatively poor.It is poor to add existing coal dust guiding device flow conductivity, and resistance is also bigger, isolated dense powder can not be flowed whole water conservancy diversion to the side of waring oneself in front of a fire, and therefore the effect of bias combustion can not be brought into play preferably.

Purpose of the present invention and task are to provide a kind of concentrated coal powder straight flow burner for pulverized-coal fired boiler, this burner not only has coal dust enrichment function preferably, can focus on dense side to the most coal dusts in airduct, and flow resistance is less, and has stronger coal dust flow conductivity.

For achieving the above object, the present invention is achieved by the following technical solutions: it comprises boiler furnace, airduct of arranged tangential and burner nozzle, this airduct comprises that centrifugal elbow reaches the coal dust guiding device thereafter, it is characterized in that adopting the elbow dense-and-weak separator of band hollow flow distribution plate internals, it is to install hollow flow distribution plate internals additional near in the airduct elbow of burner nozzle, and the radius of curvature of its hollow flow distribution plate internals should be identical with the radius of curvature of elbow center line.Experiment shows, because the flow distribution plate internals that are installed in the elbow have been destroyed the eddy current effect in the pipe effectively, thereby compare with the elbow that does not add the flow distribution plate internals, the ability of its enrichment coal dust is significantly increased, and the coal dust more than 90% in airduct can be focused on dense side.

Taking on the basis of technique scheme, for making the Fu Fenliu that is enriched in the bend pipe outside inject the side of waring oneself in front of a fire of burner hearth effectively, the present invention has also adopted the twin-feed spiral blade air deflector of band hollow stamen pipe, it is installed in the airduct of elbow back, the side of waring oneself in front of a fire of the burner hearth that the Fu Fenliu in the elbow outside almost absolutely can be led.For reducing flow resistance, under the certain situation of dust diameter, its length L should not be too short,

For further improving the steady combustion ability of unburnable coal (anthracite and soft coal etc.), also can add a preheating spout, to replace common burner nozzle at the outlet side that is loaded with an airduct of rich powder stream.This spout is by high temperature reflux smoke pre-heating breeze airflow, makes Fu Fenliu help reaching ignition temperature.

The present invention compared with prior art has following beneficial effect: 1, improved the separative efficiency of elbow effectively, owing to adopted the elbow dense-and-weak separator of hollow deflector, the coal dust more than 90% can be focused on the outside of elbow, and its flow resistance has increased not quite; 2, adopt the twin-feed spiral blade air deflector of band hollow stamen pipe, can be with the side of waring oneself in front of a fire of the almost hundred-percent guiding corner firing of the isolated rich powder stream of elbow separator, its flow resistance is less than 200Pa; 3, unburnable coal is adopted the preheating spout, further improved steady combustion performance.Adopt above-mentioned technical solution in a word, the underload oil-break that has improved boiler effectively surely fires performance (for bituminous coal≤50% rated load, meager coal≤60% rated load, anthracite≤70% rated load), reduced the discharging of NOx, not only realized the purpose of low-resistance, efficient bias combustion preferably, but also have simple in structure, advantages such as repacking and operation are convenient.

Fig. 1 is that concentrated coal powder straight flow burner is arranged and structural representation for four jiaos.It comprises the elbow dense-and-weak separator 1 of band hollow flow distribution plate internals, the twin-feed spiral blade coal dust air deflector 2 of band hollow stamen pipe, a deep or light airduct 3 and burner hearth 4.

Fig. 2 is the structural representation of the elbow dense-and-weak separator of band hollow flow distribution plate.

Fig. 3 is the A-A cutaway view of Fig. 2.

Fig. 4 is the profilograph of the twin-feed spiral blade coal dust air deflector of band hollow stamen pipe.

Fig. 5 is the structure chart of preheating spout.

Fig. 6 is the work system figure of concentrated coal powder straight flow burner band preheating spout.

Describe the specific embodiment of the present invention and embodiment in detail below in conjunction with accompanying drawing:

Fig. 2 and Fig. 3 are the concrete structures of the elbow dense-and-weak separator of band hollow flow distribution plate internals, its formation is to install hollow flow plate internals 5 additional near in the airduct elbow of burner nozzle, and the radius of curvature of these internals 5 is consistent with the radius of curvature of elbow center line; Flow distribution plate hollow pitch B should be controlled in the 1/2-1/3 scope with the ratio (B/D) of elbow diameter D, and the elbow central angle selects for use 45 °～90 ° to be advisable.Test shows, installs that the separating power of elbow is significantly increased than the separating power that does not add the internals elbow after the deflector internals additional, the coal dust more than 90% can be focused on the outside of elbow, and flow resistance do not have significant change.

Fig. 4 is the twin-feed spiral blade coal dust air deflector of band hollow stamen pipe, and it is installed in the airduct behind the elbow dense-and-weak separator.This air deflector is made up of hollow stamen pipe 7 and twin-feed spiral blade 6, and the diameter of hollow core tubes is changeable.The flow conductivity that this air deflector is 108 ° is near 100%, and for reducing resistance, the air deflector length L should not be too short.Its length preferably its diameter 3.5-7 doubly.

Giving hot spout 8 is for further improving unburnable coal: the steady combustion ability as anthracite and soft coal etc. designs, this spout is installed in the exit that is loaded with dense powder stream airduct, the high temperature reflux flue gas is given in heating the thick coal culm air-flow, so more help reaching ignition temperature.

Work system such as Fig. 1 and shown in Figure 6 of typical concentrated coal powder straight flow burner, for using anthracite or soft coal, last middle level straight-through pulverized coal burner can not add the preheating spout, adopt work system as shown in Figure 1, be coal dust behind elbow dense-and-weak separator 1 directly with rich powder stream or again through the side of waring oneself in front of a fire of twin-feed spiral blade air deflector 2 guiding corner firings, and lower floor's coal powder direct supplying burner can adopt the form (as shown in Figure 6) of band preheating spout, be that coal dust is behind the elbow dense-and-weak separator, directly Fu Fenliu is sent into preheating spout 8, and light powder stream enters the combustion chamber in company with secondary wind.Because Fu Fenliu obtained further preheating before entering the combustion chamber, shift to an earlier date more thereby make to catch fire, and had further improved the steady combustion ability of burner.For using high-volatile bituminous coal, its upper, middle and lower layer all adopts the layout pattern of Fig. 1 to be enough to also guarantee that the oil-break underload reduces to below 50%.

Claims

1, a kind of concentrated coal powder straight flow burner, comprise boiler furnace, airduct and burner nozzle, this airduct comprises centrifugal elbow and subsequent coal dust air deflector [2], it is characterized in that adopting the elbow dense-and-weak separator [1] of band hollow flow distribution plate internals, it is to install hollow flow distribution plate internals [5] additional near in the centrifugal elbow of burner nozzle, and the radius of curvature of these flow distribution plate internals is identical with the radius of curvature of elbow center line.

2,, it is characterized in that the middle Ullage B of above-mentioned hollow flow distribution plate and the ratio of centrifugal elbow diameter D (B/D) are 1/3～1/2 according to the described concentrated coal powder straight flow burner of claim 1.

3,, it is characterized in that described coal dust air deflector adopts the twin-feed spiral blade air deflector [2] of a band hollow stamen pipe according to the described concentrated coal powder straight flow burner of claim 1.

4, according to the described concentrated coal powder straight flow burner of claim 3, the length L that it is characterized in that twin-feed spiral blade air deflector should be 3.5 times-7 times of its diameter.

5,, it is characterized in that installing a preheating spout additional at a wind tube outlet place that is loaded with Fu Fenliu according to the described concentrated coal powder straight flow burner of claim 1.