CN209042433U - A kind of pneumatic conveying boiler coal-ash combustion system - Google Patents

Abstract

The utility model discloses a kind of pneumatic conveying boiler coal-ash combustion systems, are suitable for power plant boiler, cement furnace and industrial coal powder furnace.Combustion system includes primary air fan, pulverized coal bin, pulverizer coal feeder, coal, pulverulent fuel mixer, filter and coal burner and connecting pipe, and the powder feeding pipe road for being sent into coal burner through coal, pulverulent fuel mixer is connected with filter；The filter includes that entrance reamer section, straight pipe and exit constriction cone section, the inlet diameter of the entrance reamer section areEntrance diffusion angle is β, and the diameter of the straight pipe isLength is L, and the outlet diameter for shrinking cone section isThe exit constriction angle that exit constriction bores section is α.This system solves pulverized-coal fired boiler because of hearth combustion fluctuation caused by fluctuating to powder and unburned carbon in flue dust rising, and filter construction is simple, and easy to operate, using effect is good, has wide applicability.

Description

A kind of pneumatic conveying boiler coal-ash combustion system

Technical field

The utility model relates to a kind of pulverized coal combustion system, especially it is a kind of be suitable for power plant boiler, cement furnace and Pneumatic conveying boiler coal-ash combustion system in industrial coal powder furnace.

Background technique

Coal dust is widely used in power plant boiler, cement furnace and industrial coal powder furnace, although coal dust is as oil gentle one Sample is similar to fluid convenient for conveying, commonly referred to as pneumatic conveying, and conveying can be divided into diluted phase transport and two-phase transportation by gas-solid ratio again, But for the coal-powder boiler of diluted phase transport, low-load combustion-stabilizing is all a problem all the time, nearest 10 years industrial coal powders Boiler is more and more, and load change is also more frequent than station boiler before and amplitude is bigger.One for generating plant pulverized coal boiler As it is minimum not throw oily steady combustion load be the 30~40% of rated load, and industrial coal powder boiler capacity is smaller than station boiler, instead And lower oil of not throwing is required surely to fire load, therefore, it is proposed to more stringent requirement.By largely practicing, grope both at home and abroad More method is gone out.For example coal studies the coal burner that total institute has developed the inverse spray in center, the burning control of the author's unit Xuzhou Research institute processed develops double-cyclone central bluff body coal burner.But original coal dust strength for power plant is found at runtime Transportation system is difficult to adapt to, therefore also produces a large amount of coal dust conveying patent.Substantially reach such common recognition, gives powder wave It is dynamic to cause the bad furnace pressure fluctuation fire extinguishing of boiler combustion.

Patent No. CN201510660373.6 discloses a kind of method that coal dust firing generates high temperature hyperoxia torch ignition, Even if finding that the precombustion chamber misfires in practice also functions to certain steady combustion effect.But it can not meet " thermal power plant cigarette wind Pulverized coal channel designing technique regulation ", 9.4.9 item defines pulverized coal channel conveying speed not less than 18m/ in DL/T5121-2000 S, pulverized coal carried by hot air are not less than 25m/s；7.2.3 it is preferably 7-15 degree that item, which gives pipeline angle of flare, and collapsible tube optimum angle is 25 degree.Specially Benefit number discloses the chain-grate boiler coal dust transfer pipeline of secondary pressure system for CN201510521968, adds in chain furnace coal powder injection Buffer unit is entered, which is considered that pressure oscillation causes detonation, in order not to set with thermal power plant cigarette wind pulverized coal channel The regulation of 9.4.9 item mutually conflicts in meter technical regulation DL/T5121-2000, self limits its scope of application and only belongs to chain pot Furnace coal dust transfer pipeline, the cross-sectional flow area by the dsah-pot I described in it is 2-8 times of normal pulverized coal channel, by pulverized coal channel Normal minimum design current velocity 18m/s, then the minimum design current velocity of dsah-pot is 2.25m/s, dsah-pot is substantially that flow velocity is lower Air flow bed, do not reach the standard recycled in fluidized bed.Patent No. CN201510521968 discloses middle flow velocity and angle It all without the regulation for abiding by the above regulation, does not also give an explaination, can not justify oneself in the above-mentioned patent of application, there are serious Accident potential, it is insufficient on practicability.

For the coal powder conveying system of normal operation, all there is give for Impeller powder feeder, screw(-type) feeder, star-shaped feeding machine Powder fluctuation, by taking the most common Impeller powder feeder as an example, normal revolving speed is at 20~80 revs/min, and classical pulverizer coal feeder blender is only There are 2 blades, theoretically coal powder light-dark period of change T has reached 1 second grade, that is, typical vibration frequency to 12 powder allocation blades Near 1Hz, for normal coal flame from the point of view of optical spectrum analysis, vibration frequency concentrates on 30-120Hz, the dominant frequency of oily flame It is higher, it is clear that almost unrelated with fire extinguishing in the fluctuation of 30Hz frequencies above.Normal dilute phase powder feeding wind speed 20~30m/s it Between, 0.1 second disconnected powder cause 2 meters of spout long be enough without fiery distance cause furnace flame stripping, this is to cause boiler combustion bad The theoretical reasons of furnace pressure fluctuation fire extinguishing.In actual operation it is observed that such phenomenon, if stokehold oil system exists The caliber of stokehold is thinner, and when only 2 oil guns, when actual ignition is frequently occurred in when throwing the 2nd oil gun the 1st to catch fire A oil gun band goes out, this is fire extinguishing caused by of short duration fuel slash caused by typical oil pressure bust, increases stokehold oil system caliber Such case can be usually eliminated afterwards.We also observe pulverizer coal feeder occasionally there are unexpected revolving speeds to become pulverized-coal fired boiler in actual operation There is short interruption in the case where restoring revolving speed again in slow 1~3 second when hardened piece in coal dust passes through pulverizer coal feeder sometimes, this to give powder Fluctuation is the immediate cause for causing burner hearth to be put out a fire suddenly, even this fluctuation is preferable in quality of pc, when boiler load is higher It can not avoid completely.In practice we have found that coal dust humidity be under the influence of the successional major reason of powder, coal dust humidity is big When easily occur continuously cause to put out a fire to powder, lead to combustion chamber draft fluctuation not putting out a fire, unburned carbon in flue dust rises； In addition the longer mobility of coal dust storage time is also poorer.

Since flow velocity of the wind powder mixture in pulverized coal channel be not small according to the regulation of 9.4.9 item in DL/T5121-2000 To consider that Dual-Phrase Distribution of Gas olid does not deposit in horizontal pipe in 18m/s, this regulation in fact with the gas-solid of vertical pipe two Mutually the safety of stream transports no any relationship.18m/s is only to consider that deposition does not occur for Dual-Phrase Distribution of Gas olid stifled in horizontal pipe Plug, the stationarity of its not guaranteed flowing, in practice to guaranteeing that flowing is steady in horizontal pipe, flow velocity is suitable in pulverized coal channel In 25m/s or more, and the rate of wear of pipeline is directly proportional to the cube of flow velocity, so flow velocity is usually only in 25m/ in pipeline S or so.It is considered that by pulverized coal channel horizontal pipe and vertical pipe distinguish, be solve coal dust mobility it is unstable Good method.For the pulverized coal particle between common R90=10-40 (170-200 mesh), critical fluidisation in a fluidized bed Speed is between 0.2~0.5m/s, it is contemplated that safety, safe transport velocity is 1m/s in vertical pipe.

The fluctuation of coal dust pneumatic conveying and the fluctuation analogy of direct current, direct current filtering generally use capacitive filter (C Filter), choke-condenser filter (LC filter), the circuits such as pi filter filter, for coal dust, we must find conjunction Suitable filtering mode.No matter it is that field electronics temporarily stores which kind of electrofiltration wave, which is all by electrotransformation, corresponding coal dust pneumatic transporting It send and should also be as stored electrons that storage section coal dust is among suitable system, when coal powder density is diluter in system, It can release in time, part coal dust can be stored when coal powder density is high.Engage fluctuation of the pulverized coal flame before underload fire extinguishing Frequency is mainly 0.2-5Hz, and therefore, the filtering main object of coal dust pneumatic conveying should be the low-frequency fluctuation of 0.2-5Hz.We Analogue simulation filtering of the self-designed filter to the square-wave signal of cycle T=3s and T=6s, effect are satisfied.Through It practices the filter to be applied to after engineering, the fluctuation of combustion chamber draft is obviously suppressed, and clinker and unburned carbon in flue dust have obviously Reduction, although the index of the back yard industry coal-powder boiler of 60t/h, clinker and unburned carbon in flue dust is better than the 600MW grades of main forces The average level of unit.

Summary of the invention

Technical problem: the purpose of utility model is to provide a kind of band filter in place of wanting overcome the deficiencies in the prior art Pneumatic conveying pulverized coal combustion system solves pulverized-coal fired boiler because boiler combustion caused by fluctuating to powder is bad, furnace pressure fluctuation goes out Fire and unburned carbon in flue dust rise.

Technical solution: a kind of pneumatic conveying boiler coal-ash combustion system of the utility model, including primary air fan, coal dust Storehouse, pulverizer coal feeder, coal, pulverulent fuel mixer, filter and coal burner and connecting pipe, it is described to be sent into coal dust combustion through coal, pulverulent fuel mixer The powder feeding pipe road of burner is connected with the filter that mean wind speed is 0.5-3m/s；The filter include entrance reamer section, Straight pipe and exit constriction bore section, and the inlet diameter of the entrance reamer section isEntrance diffusion angle is β, the straight pipe Diameter is2, length L, the outlet diameter for shrinking cone section areThe exit constriction angle that exit constriction bores section is α.

The filter is vertically arranged or is arranged in the range of with plumb line at 20 degree of angles.

L=6-9 meters of the flow development length of the filter.

The diameter of the straight pipe of the filterIt is inlet diameter2.8-5.5 times.

Entrance diffusion angle β=7-60 degree of the entrance reamer section of the filter, preferably 20-40 degree.

The exit constriction angle of the exit constriction cone section of the filter is α=15-60 degree, preferably 20-40 degree.

In the straight pipe of the filter mean wind speed be 1-2 meters/it is per second.

The utility model has the advantages that as the above scheme is adopted, caused by the utility model is solved because of as-fired coal powder fluctuation of concentration Combustion instability is even put out a fire, and coal dust firing is stable, negative pressure fluctuates small and small unburned carbon in flue dust problem.It exports and receives in filter Contracting cone section, wind preferentially accelerate, and the initial velocity of powder is 1m/s, and the speed of powder seriously lags behind wind speed, variable accelerated motion is done after by wind, Shrinking the outlet of cone section away from burner nozzle is 2.5 meters, and burner nozzle wind speed is 20m/s, solves inclined gentle breeze equation and obtains burner The speed of spout powder is only capable of reaching 9m/s.The combustion stability of coal dust can be greatly improved, while unburned carbon in flue dust also has It is apparent to improve.Used filter length L connects diffusion on vertical ascent powder feeding pipes in filter between 6-9 meters Angle beta=7-60 degree reamer, since vertical ascent pipeline section becomes larger after reamer, the mean wind speed 1- in vertical ascent pipeline 2m/s, to form the flow field in similar fluidized bed in vertical ascent pipeline, coal dust rises with air-flow among pipe, and closely manages Part coal dust forms membranaceous decline at wall, and part coal dust, which is stored in filter, forms interior circulation, forms fluidized bed, reduces Variation because entering burner coal dust amount caused by fluctuating to powder；By taking powder feeding pipes DN200 filters out the period as the fluctuation of 6s as an example, filtering L >=T/v=6/1.5=4 meters of device length.Its structure is simple, easy to operate, and using effect is good, has in the art wide General practicability.

Detailed description of the invention

Fig. 1 is the system structure diagram of the utility model.

Fig. 2 is the filter graph architecture of the utility model.

Wherein: 1, primary air fan, 2, pulverized coal bin, 3, pulverizer coal feeder, 4, coal, pulverulent fuel mixer, 5, filter, 6, coal burner,Inlet diameter,Straight pipe diameter,Outlet diameter, β, entrance diffusion angle, α, exit constriction angle, L, straight pipe Length；

Specific embodiment

The utility model will be further described for embodiment in reference to the accompanying drawing:

A kind of pneumatic conveying boiler coal-ash combustion system of the utility model, mainly by primary air fan 1, pulverized coal bin 2, to powder Machine 3, coal, pulverulent fuel mixer 4, filter 5 and coal burner 6 and connecting pipe, it is described to be sent into coal dust firing through coal, pulverulent fuel mixer 4 The powder feeding pipe road of device 6 is connected with the filter 5 that mean wind speed is 0.5-3m/s；The filter 5 be vertically arranged or with Plumb line in the range of 20 degree of angles at being arranged.The filter 5 includes entrance reamer section, straight pipe and exit constriction cone Section, the inlet diameter of the entrance reamer section areEntrance diffusion angle is β, and the diameter of the straight pipe isLength is L, Entrance diffusion angle β=7-60 degree of the entrance reamer section of the filter 5, preferably 20-40 degree；The straight pipe of the filter 5 DiameterIt is inlet diameter2.8-5.5 times；L=6-9 meters of the flow development length of the filter 5, in straight pipe Mean wind speed be 1-2 meters/it is per second.It is described shrink cone section outlet diameter beThe exit constriction angle that exit constriction bores section is α, The exit constriction angle of the exit constriction cone section of the filter 5 is α=15-60 degree, preferably 20-40 degree.

Embodiment: the straight pipe diameter of filter 5It is inlet diameter2.8-5.5 times, design straight pipe in wind Speed is 0.5-3m/s, preferred 1-2m/s, the flow development length L=3-20m, preferred 6-9m of filter.Filter 5 can also be with It is the structure type of entire vertical tube and elbow.Entrance diffusion angle β=7-60 degree, preferred 20-40 degree；Exit constriction angle α= 15-60 degree, preferred 20-40 degree.

The course of work: when coal dust is fallen from powder cabin 2, enter coal, pulverulent fuel mixer 4 after the metering of pulverizer coal feeder 3 and neutralize from primary The wind that blower 1 comes conveys after mixing in coal, pulverulent fuel mixer 4 through pulverized coal channel, enters after elbow turning enters increase in pipeline In filter 5, after being filtered in filter 5 through pipeline into burner 6.

The access port diffusion angle β after horizontal pipe elbow after powder feeding pipes band powder, the increase in pipeline section after reamer become larger, Mean wind speed forms the cold flow field in similar fluidized bed, coal dust among pipe in 1-2m/s in increase in pipeline in increase in pipeline Rising with air-flow, coal dust forms membranaceous decline at nearly tube wall, and part coal dust, which is stored in vertical ascent pipeline, forms interior circulation, Form fluidized bed, enter the variation of burner coal dust amount caused by reducing because of the fluctuation of entrance coal powder density, entering at combustor elbow or Tapered again after elbow to reach normal wind speed in burner, pipeline angle of throat is 20-40 degree, and wind accelerates first in collapsible tube, coal Powder accelerates after by wind, and wind speed is still higher than coal dust speed at burner nozzle, increases the coal dust residence time, is conducive to kindling and combustion To the greatest extent.

9.4.9 item defines pulverized coal channel pneumatic conveying speed not less than 18m/s in DL/T5121-2000, which is It is provided under the same conditions in horizontal feed pipeline and vertical ascent pipeline sectional area, considers horizontal pipe pneumatic conveying safety The speed of speed not plugging simultaneously provides 18m/s after reserving safe clearance, which does not consider gas in vertical ascent conveyance conduit Only 1m/s with horizontal tube differs larger to the safe speed of power conveying.Floating velocity of the typical coal dust in vertical ascent pipeline be 0.3m/s, the actual motion speed referring to recirculating fluidized bed are usually 2-3 times of critical fludization velocity, therefore, upward vertical tube In road permissible velocity it is suitable > 1.0m/s.By taking normal pulverized coal channel design current velocity 25m/s as an example, design current velocity is 1-2m/ in filter S, average v=1.5m/s, will filter out the fluctuation that the period is T=3s, and L >=T/v=3/1.5=2 meters of filter length；If filtered Except the period be 6s fluctuation, L >=T/v=6/1.5=4 meters of filter length.Coal dust is deposited on when in order not to cause unexpected blowing-out Pipeline extreme lower position results in blockage, and coal dust position is easily deposited under filter, the maintenance door for drawing powder is preferably arranged；In order to filter out Coal dust fluctuation again will not filter is too long that stifled powder fault spread and investment is caused to rise, usual filter length L is not preferably greater than 20 Rice, preferred L is preferably between 6-9 meters.By normal circular pipe, the diameter of filter straight pipe is normal level pulverized coal channel 2.8-5.5 times of diameter, preferred 3-4 times.

Claims (7)

1. a kind of pneumatic conveying boiler coal-ash combustion system, including primary air fan (1), pulverized coal bin (2), pulverizer coal feeder (3), coal dust are mixed Clutch (4), filter (5) and coal burner (6) and connecting pipe, it is characterised in that: described to be sent into through coal, pulverulent fuel mixer (4) The powder feeding pipe road of coal burner (6) is connected with the filter (5) that mean wind speed is 0.5-3m/s；The filter (5) Section is bored including entrance reamer section, straight pipe and exit constriction, the inlet diameter of the entrance reamer section is φ 1, entrance diffusion angle For β, the diameter of the straight pipe is φ 2, length L, and the outlet diameter for shrinking cone section is φ 3, and exit constriction bores section Exit constriction angle is α.

2. pneumatic conveying boiler coal-ash combustion system according to claim 1, it is characterised in that: the filter (5) It is vertically arranged or is arranged in the range of with plumb line at 20 degree of angles.

3. pneumatic conveying boiler coal-ash combustion system according to claim 1, it is characterised in that: the filter (5) L=6-9 meters of flow development length.

4. pneumatic conveying boiler coal-ash combustion system according to claim 1, it is characterised in that: the filter (5) The diameter phi 2 of straight pipe is 2.8-5.5 times of inlet diameter φ 1.

5. pneumatic conveying boiler coal-ash combustion system according to claim 1, it is characterised in that: the filter (5) Entrance diffusion angle β=7-60 degree of entrance reamer section.

6. pneumatic conveying boiler coal-ash combustion system according to claim 1, it is characterised in that: the filter (5) The exit constriction angle that exit constriction bores section is α=15-60 degree.

7. pneumatic conveying boiler coal-ash combustion system according to claim 1, it is characterised in that: the filter (5) Mean wind speed is 1-2m/S in straight pipe.