Flue gas drying brown coal steel ball powder-grinding system
Technical field
The utility model belongs to the coal fired power generation technical field, relates to the brown coal generation technology, specifically, relates to the pulverized coal preparation system of combustion brown coal station boiler.
Background technology
Brown coal are the minimum pit coals of degree of coalification, are peat depositions after dehydration, compacting change the initial stage product of organic-biological rock into, because of appearance is brown or crineous is gained the name.Brown coal account for 18% of China's thermal coal reserves, mainly are distributed in areas such as the Inner Mongol, northeast and Yunnan.Brown coal have volatile matter height (V
Daf>37%) characteristics such as high-moisture (total moisture is about 30%, and free moisture surpasses 19% mostly), caloric value low (about 12.56MJ/kg), ash fusion point low (about 1150 ℃), low (HGI is 50-70) of abrasiveness and easy spontaneous combustion.The characteristics of brown coal " two Senior Three are low " have determined that its pulverized coal preparation system has certain particularity.
Brown coal are mainly used in Power Plant Fuel, also can be used for fields such as chemical industry.The brown coal generating is widely used in developed countries such as Australia, Germany, the U.S..Research points out that the brown coal behind the burning drying and upgrading can improve boiler efficiency, reduce exhaust gas temperature, reduce the energy consumption of power plant auxiliary machines such as air-introduced machine, coal pulverizer, reduce gross coal consumption rate, improve plant thermal efficiency, simultaneously to reducing CO
2, NO
XDischarging is also played a role.
At present, domestic electric coal strained market supply, state's ore deposit electricity coal price lattice are high.For ensureing the long-term stability supply of electric coal, and control Power Plant Fuel cost, a large amount of power plant begin to explore and test in all kinds of coal-fired units, to mix to burn cheap brown coal.Higher and inflammable and explosive because of brown coal moisture, so becoming, dry undercapacity of pulverized coal preparation system and explosion of Coal Pulverizing System hidden danger restricts the key factor that burning brown coal is mixed by power plant.
In the station boiler pulverized coal preparation system, the difference of the maximum of all kinds of pulverized coal preparation systems is the coal pulverizer type.The coal pulverizer of widely using at present mainly contains low speed coal mill, medium-speed pulverizer and blower mill three major types, wherein adopts the pulverized coal preparation system of low speed coal mill to account for China at 60% of labour station boiler pulverized coal preparation system.Therefore, existing ball mill pulverizing system is improved, make it satisfy the requirement that vast scale is mixed burning brown coal or ground the high-moisture brown coal, all have remarkable economical and environmental benefit in labour and newly-built station boiler what adopt steel ball powder-grinding system.
A large amount of brown coal are mixed and are burnt test and confirmed already, adopt 350~450 ℃ hot blast to be difficult to satisfy the dry demand of high-moisture brown coal as drier.The dry undercapacity of pulverized coal preparation system not only makes the coal powder performance variation, also influences coal pulverizer simultaneously and grinds to exert oneself and cause boiler output lower, makes to mix to burn to lose meaning.And the further raising of hot blast temperature receives the restriction of air preheater and coal pulverizer bearing allowable temperature.In addition; The explosion-proof performance of bin storage type pulverizing system is relatively poor; Brown coal are inflammable and explosive in addition, thus adopt hot blast or hot blast to demand technological improvement urgently as the steel ball powder-grinding system of drier with stove cigarette mixture so that low speed coal mill can be safely, economy, efficiently grind the high-moisture brown coal.
The utility model content
The utility model technical problem to be solved provides a kind of flue gas drying brown coal steel ball powder-grinding system; This pulverized coal preparation system is that existing steel ball powder-grinding system is transformed; The safety in operation that overcomes the dry high-moisture brown coal undercapacity of existing steel ball powder-grinding system and improve steel ball powder-grinding system; But make the coal-fired unit vast scale that contains steel ball powder-grinding system mix burning brown coal or whole burning high-moisture brown coal, can also realize reducing simultaneously cost of electricity-generating.
For solving the problems of the technologies described above, the utility model adopts following technical scheme:
A kind of flue gas drying brown coal steel ball powder-grinding system comprises low speed coal mill, mill separator, hot air apparatus, and said hot air apparatus divides two-way, and one the tunnel connects burner; The coal outlet of said low speed coal mill connects the import of mill separator; The meal outlet of said mill separator connects the coal feed point of low speed coal mill again; It is characterized in that: said low speed coal mill is connected with pre-drying device at coal feed point, and said pre-drying device has coal feed point and high temperature flue gas drying agent inlet on top; The fine powder outlet of said mill separator connects pulverized-coal collector; The meal outlet of pulverized-coal collector connects machine supplying powder; Machine supplying powder connects air and powder mixer, and the bellows in another road of said hot air apparatus also connect air and powder mixer, and said air and powder mixer is connected to the burner of boiler; The weary gas outlet of said pulverized-coal collector connects deduster, and the meal outlet of deduster connects machine supplying powder again, and the gas outlet of deduster connects weary gas blower fan.
Adopt technique scheme; Through a pre-drying device is set before low speed coal mill; And utilize high-temperature flue gas in pre-drying device, to carry out predrying to brown coal as drying medium; Can promptly realize and in the coal-fired unit that adopts steel ball powder-grinding system, to have mixed burning brown coal or clean burn brown coal by vast scale so that the moisture in the brown coal reduces to adapt to the operating mode of low speed coal mill like this.And further replace hot blast as required drier and the ventilation medium of low speed coal mill operation with high-temperature flue gas.Because oxygen content is lower in the high-temperature flue gas, is inert gas, this just makes low speed coal mill safer when grinding brown coal, has eliminated the hidden danger of brown coal detonations, the security that has improved pulverized coal preparation system.Hot air apparatus divides two-way through hot air duct, and one the tunnel connects the burner of boiler, and another road is connected to air and powder mixer, and air and powder mixer is connected to burner.Through hot blast the brown coal that drying grinds are sent into burner so again, can suitably improve the wind-warm syndrome degree one time on the one hand, improve the flammability of fuel, make the boiler low load stable combustion performance strengthen, guaranteed the primary air ratio that coal dust firing is required on the other hand.Extract out owing to will contain the weary gas of brown coal drying of a large amount of water vapours through deduster, weary gas blower fan, make a large amount of former moisture content of coals not get into boiler furnace, fire box temperature is improved; Thereby significantly improve coal powder performance; The boiler exhaust gas heat loss is reduced, and boiler efficiency is improved, and can reduce air-introduced machine, coal pulverizer power consumption in addition; Thereby unit efficiency is improved, and gross coal consumption rate reduces.
Said weary gas blower fan also connects weary gas cooler, and weary air cooling but utensil has the weary gas outlet of condensation-water drain and dehydration.Through weary gas cooler, the large quantity of moisture in the recyclable weary gas of one side, the heat energy that weary on the other hand gas cooler reclaims returns the Unit Steam Water circulatory system, can further improve generating set efficient.
For realizing that the temperature that gets into the high-temperature flue gas in the drying device is regulated; In the utility model; The high temperature flue gas drying agent inlet of said pre-drying device is connected with flue gas mixing-chamber; Said flue gas mixing-chamber has two gas approach, and one of them gas approach is connected at the smoking mouth of boiler furnace, and another gas approach connects the weary gas outlet of dehydration of weary gas cooler or/and the cold smoke of boiler flue afterbody is taken out mouth.
Also be connected with Pulverized Coal Bin before the said machine supplying powder, the meal outlet of said pulverized-coal collector and the meal outlet of deduster all are connected to this Pulverized Coal Bin.In machine supplying powder the place ahead Pulverized Coal Bin is set, can makes pulverized coal preparation system not receive the influence of boiler load, guarantee that pulverized coal preparation system can be stablized, efficiently operation.
In addition, the weary gas outlet of the dehydration of said weary gas blower fan and weary gas cooler also is directly connected to desulfurizing tower.
Also be provided with cigarette wind mixing chamber between said hot air apparatus and the air and powder mixer, said cold smoke is smoked mouth and also is connected to this wind mixing chamber.Such wind wind-warm syndrome can be regulated through change hot blast, cold smoke ratio.
Description of drawings
Through the description of its exemplary embodiment being carried out below in conjunction with accompanying drawing, the above-mentioned feature and advantage of the utility model will become apparent and understand easily.
Fig. 1 is the system construction drawing of the utility model.
The specific embodiment
As shown in Figure 1; The flue gas drying brown coal steel ball powder-grinding system of the utility model; Comprise former coal bunker 1; Feeder 2, pre-drying device 3, steel ball mill 4, mill separator 5, powder retrieving pipe 6, pulverized-coal collector 7, Pulverized Coal Bin 8, machine supplying powder 9, pressure fan 11, air preheater 12, air supply duct 13, secondary wind bellows 14, primary air fan 15, cigarette wind mixing chamber 16, airduct road 17, bellows 18, air and powder mixer 19, cold smoke blower fan 23, cold smoke pipeline 24, cold smoke branch pipe(tube) 25, flue gas mixing-chamber 26, high temperature boiler flue gas tube road 27, sack cleaner 28, weary gas blower fan 29, weary gas cooler 30, the weary gas blower fan 31 of dehydration, blast pipe road 32.
Wherein, pre-drying device 3 is descending drying tube, has coal feed point and high temperature furnace cigarette desiccant inlet on top, and the bottom has coal outlet.
Former coal bunker 1 outlet connects feeder 2, and feeder 2 is connected to the coal feed point of pre-drying device 3, and the coal outlet of pre-drying device 3 is connected to the coal feed point of low speed coal mill 4.The coal outlet of low speed coal mill 4 connects the import of mill separator 5; The meal outlet of mill separator 5 connects the coal feed point of low speed coal mill 2 again through powder retrieving pipe 6; The fine powder outlet of mill separator 5 connects pulverized-coal collector 7; The weary gas outlet of pulverized-coal collector 7 connects sack cleaner 28; The meal outlet of the meal outlet of pulverized-coal collector 7 and sack cleaner 28 all is connected to Pulverized Coal Bin 8, and Pulverized Coal Bin 8 is connected to air and powder mixer 19 through machine supplying powder 9 again, and air and powder mixer 19 is connected to the burner 20 of boiler 10.The gas outlet of sack cleaner 28 connects weary gas blower fan 29, and weary gas blower fan 29 is being connected to weary gas cooler 30.Weary gas cooler 30 is heat exchangers, has condensation-water drain and the weary gas outlet of dehydration.
The high temperature flue gas drying agent inlet of pre-drying device 3 is connected to flue gas mixing-chamber 26 through high temperature boiler flue gas tube road 27, and flue gas mixing-chamber 26 has two gas approach, and one of them gas approach is connected to the hot cigarette of boiler 10 burner hearths and takes out mouth 21.And the cold smoke of the flue afterbody of boiler 10 is taken out mouthfuls 22 and is connected with cold smoke blower fan 23; The weary gas outlet of the dehydration of weary gas cooler 30 is connected with the weary gas blower fan 31 of dehydration, and cold smoke blower fan 23 all is connected to another gas approach of flue gas mixing-chamber 26 through blast pipe road 32 through cold smoke branch pipe(tube) 25, the weary gas blower fan 31 of dehydration.So just can in flue gas mixing-chamber 26, high temperature furnace cigarette and cold smoke or the weary gas that dewaters be mixed, thereby the high temperature furnace cigarette is carried out temperature adjustment.
Hot air apparatus is made up of pressure fan 11, primary air fan 15 and air preheater 12; Wherein, Air preheater 12 is located in the flue of boiler; Pressure fan 11 links to each other with air preheater 12 outward with the flue that primary air fan 15 is positioned at boiler 10,12 fens two-way of air preheater, and the air supply duct 13 of leading up to is connected to the burner 20 of boiler 10 through secondary wind bellows 14; Another road is connected to cigarette wind mixing chamber 16, and cigarette wind mixing chamber 16 is connected to air and powder mixer 19 through an airduct road 17 through wind bellows 18, and cold smoke blower fan 23 is also connected to this flue gas mixing-chamber 16 in addition.
More than be exactly the flue gas drying brown coal steel ball powder-grinding system of the utility model, its working method is following:
Raw coal is sent into descending drying tube 3 from former coal bunker 1 through feeder 2; Descending drying tube 3 tops mix with drier from flue gas mixing-chamber 26 and under be advanced into low speed coal mill 4 and grind; Wind powder mixture after grinding gets into mill separator 5; Isolated meal is sent coal pulverizer 4 back to by powder retrieving pipe 6 and is continued to grind, and fine powder and weary gas get into pulverized-coal collector 7, and most coal dusts are by pulverized-coal collector 7 separation and fall into Pulverized Coal Bin 8; A small amount of fine powder gets into sack cleaner 28 with weary gas and further carries out gas solid separation; The fine powder that sack cleaner 28 reclaims returns Pulverized Coal Bin 8, and weary gas is sent into weary gas cooler 30 by weary gas blower fan 29 and further is cooled to below the water dew point temperature to reclaim moisture and the heat energy in the weary gas, also can directly send into desulfurizing tower 34 by weary gas blower fan 29; The heat energy that weary gas cooler 30 reclaims returns power plant's boiler circuit through cooling water; The weary gas of low temperature dewatering that weary gas cooler 30 is discharged is carried by the weary gas blower fan 31 of dehydration, and the weary gas of part dehydration returns flue gas mixing-chamber 26 recycles as temperature control medium, and remaining part is discharged into desulfurizing tower 34; The condensate that weary gas cooler 30 is discharged both can be recycled after treatment, also can directly be discharged into desulfurizing tower wastewater disposal basin 33 and focus on.
The hot cigarette that gets into flue gas mixing-chamber 26 is taken out mouthful 21 extractions by the negative pressure of low speed coal mill 4 inlets from the hot cigarette of burner hearth; When arranging weary gas cooler 30 and its work; The weary gas of dehydration that cold smoke is carried by weary gas blower fan 31 of dehydration and blast pipe road 32 provides; Perhaps by the weary gas of dehydration with take out mouthfuls 22 from cold smoke and mix in the lump as temperature control medium with the cold smoke of cold smoke branch pipe(tube) 25, do not arrange that cold smoke was not taken out mouth 22 extractions by cold smoke blower fan 23 from the cold smoke of the flue afterbody of boiler 10 when weary gas cooler 30 or weary gas cooler 30 were not worked.Hot cigarette, cold smoke (or the weary gas of dehydration) mix at flue gas mixing-chamber 26, send into descending drying tube 3 as ventilation and drying medium then.The flue-gas temperature of flue gas mixing-chamber 26 outlets is regulated through changing hot and cold cigarette (or the weary gas of dehydration) ratio.
Hot blast from primary air fan 15 and air preheater 12 outlets mixes at wind mixing chamber 16 with the cold smoke of smoking mouth 22 from cold smoke; Send into wind bellows 18 as wind and defeated powder medium one time via an airduct road 17, through wind bellows 18 distribute after by air and powder mixer 19 pulverized coal conveyings to each burner 20.One time the wind wind-warm syndrome is regulated through change hot blast, cold smoke ratio.Hot blast from pressure fan 11 and air preheater 12 outlets is sent to each burner 20 participation stove internal combustion as secondary wind after secondary wind bellows 14 distribute.
The flue gas drying brown coal steel ball powder-grinding system of the utility model compares with existing steel ball powder-grinding system, has following characteristics:
(1) drier is mixed with cold smoke by hot cigarette and gets, and oxygen concentration is very low, and whole pulverized coal preparation system moves under inert atmosphere, and security obviously improves.
(2) high temperature furnace cigarette temperature is regulated the drier initial temperature more than 800 ℃ through changing hot and cold cigarette ratio, makes that drier drying capacity adjustable range is big, can satisfy the dry demand of all kinds of high-moisture raw coal.
(3) raw coal does not get into boiler furnace at the moisture that descending drying tube and mill drying go out, and can significantly improve coal powder performance, improves boiler efficiency simultaneously, and reduces air-introduced machine, coal pulverizer power consumption, thereby reduce gross coal consumption rate.
(4) not directly emptying of weary gas, a part is as temperature control medium recycle in pulverized coal preparation system, and remaining part is discharged into desulfurizing tower, so environmentally safe.
(5) this patent system both can be applicable to mix burning at the brown coal of labour unit, also can be applicable to the station boiler of whole burning high-moisture brown coal.
It should be noted that; Above content is the further explain that combines concrete embodiment that the utility model is done; The specific embodiment that can not assert the utility model only limits to this; Under the above-mentioned guidance of the utility model, those skilled in the art can carry out various improvement and distortion on the basis of the foregoing description, and these improve or distortion drops in the protection domain of the utility model.