Straw low temperature gasification melt-combustion method
Technical field
The present invention relates to a kind of straw low temperature gasification melt-combustion method, belong to the technical field that stalk is handled.
Background technology
The energy is the prerequisite and the basis of human survival and development.Mankind nowadays is not only brought serious pollution to environment to the very big dependence of fossil energy, and because the scarcity gradually of this energy also will become following social potential collision hazard.Under the dual-pressure of the energy and environment, make the mankind have to begin seek a kind of relatively regenerative resource of cleaning, and stalk is one of at present more satisfactory selection, it has following characteristics: 1. recyclability; 2. low contaminative; 3. distributivity widely.Utilize straw power generation, not only can be power-shortage area valuable electric power is provided, and can improve the atmosphere acid rain environment, reduce carbon dioxide content in the atmosphere, highly beneficial to environmental protection.At present, in the straw power generation technology, comparative maturity two types of direct combustion power generation and gasifying electricity generations are arranged.
Aspect the direct combustion power generation of stalk, be representative abroad with Denmark BWE company, directly burning produces steam in boiler dedicated, is converted to electric energy by steam turbine generator.At present existing more application example.China has introduced this technology, sets up demonstration project.The little suspension combustion share of densified straw height, volatile matter accounts for more than 70% in the stalk, the combustion furnace internal combustion is organized and is very easily produced carbon black when bad, it is the carbon black after the agglomerated, its particle diameter is also mostly below 10 μ m, make these carbon blacks burn fully, need higher ignition temperature, but because alkali metal, content of halogen are higher in the stalk, easily cause coking in the stove during high temperature, in fluid-bed combustion furnace, alkali-metal compound easily forms the eutectic point compound with the bed material, causes normally fluidisation of fluid bed slagging scorification especially.Also there are in difficult stable, the flue gas of high low temperature burn into burning problems such as floating dust content height when simultaneously stalk directly burns.
The gasifying stalk generation technology can be divided three classes: 1. the combustible gas of gasification furnace generation drives generator for electricity generation in the gas turbine internal combustion.Gas turbine must carry out corresponding transformation, and the combustible gas that calorific value is lower is pressurized between the 0.5-3.0MPa, otherwise generating efficiency is lower.2. combustible gas burns at internal combustion engine and drives generator for electricity generation.Preceding dual mode requires combustible gas stable, and must purify.Adopt traditional fixed bed or fluid bed to the stalk direct gasification, tar content is higher in the combustible gas of generation, and present control techniques is difficult to make it remove fully, can cause pipeline blockage and carbon deposit like this, has a strong impact on gas turbine and internal combustion engine stable operation.3. combustible gas is produced steam and is driven the steam turbine generator generating as the fuel combustion of steam boiler.This mode can keep stable fired state when gas componant and calorific value change.But the ignition temperature of steam boiler is subjected to the restriction of distinctive alkali metal, halogen in the stalk equally.
Summary of the invention
Technical problem: the present invention is directed to problems such as coking in the stove that occurs at present, pipeline tar obstruction in utilizing the straw power generation process, propose a kind of straw low temperature gasification melt-combustion method, this method has continuously, stable and safe effect.
Technical scheme: gasifying stalk melting method of the present invention is:
(1) stalk carries out low temperature gasification in circle fluidized-bed gasification furnace, and gasification temperature is 400-650 ℃.Have a large amount of inert bed materials in the fluid bed, can heat the stalk that newly advances stove rapidly and make it reach the gasification reaction temperature, its heat accumulation function also can reduce because reinforced inhomogeneous, stalk kind and moisture change temperature fluctuation in the stove that causes.
(2) the gasification furnace outlet is provided with high temperature cyclone separator, to take the outer fine grained inert bed material of stove out of with combustible gas separates, again send gasification furnace back to through material returning device, in stove, form the circulation of high concentration particle material with this, its heat carrier function can make gasification furnace reach unanimity along the short transverse temperature, be beneficial to efficient dechlorination in gasifying stalk reaction, the stove, and prevent coking in the stove.
(3) in gasification furnace, add adsorbent such as lime, can orientation remove after the pollutants, particularly degree of depth dechlorination such as sulphur, chlorine, fluorine, can prevent the high temperature corrosion of metal material, therefore can adopt conventional material to make the waste heat boiler of back, the expense of reducing investment outlay greatly, and realize efficient generating.
(4) combustible gas that produces of gasification furnace carries not the carbon containing soot particle of complete reaction and enters high temp, vertical whirlwind melting furnace and carry out melt-combustion, and ignition temperature is 1000-1500 ℃, and gas residence time is 2-3s, can guarantee that carbon contained in fuel gas and the ash burns fully.Ash after burning is molten condition and enters the chilling tank from the melting furnace bottom.
(5) high-temperature flue gas of melting furnace discharge passes through air-introduced machine from the chimney emptying at last successively by radiant type evaporating heating surface, superheater, economizer, air preheater and the deduster of waste heat boiler.High temperature that waste heat boiler produces or middle temperature superheated steam enter steam turbine generator and generate electricity by way of merging two or more grid systems.The part vapour of an alkali metal that gasifying stalk and melt-combustion produce condenses on the radiant type evaporating heating surface, through rapping and purging, a part falls into radiant type evaporating heating surface bottom ash bucket, all the other enter back-end ductwork and deduster with flue gas, are captured by back-end ductwork below ash bucket and deduster respectively.
When (6) stalk gasifies in gasification furnace, wherein contained alkali metal part can migrate to the inert bed material surface, when inert bed material surface alkali metal content reaches finite concentration, bonding mutually will take place in inert bed material, cause the gasification furnace fluidisation to worsen when serious, influence gasification furnace and normally move, therefore need regular discharge section bed material.The hott bed material of discharging enters the bosh of gasification furnace bottom, can add gasification furnace as the bed material again after the regeneration of water logging bubble.
(7) separated into two parts after air is preheating to 300-400 ℃ in air preheater, a part enters gasification furnace, carries out gasification reaction as gasifying medium and stalk; All the other enter melting furnace as combustion air, and the carbon in fuel gas and the ash is burnt fully.
(8) waste water of the flying dust of waste heat boiler and deduster collection and immersion bed material all contains abundant alkali metal, and these alkali metal are that the plant growth is necessary, and directly as fertilizer sources (as potash fertilizer) imposes on the farmland.
The fluidized gasification fusion technology early is used in domestic waste, as the weak former formula of Japanese ebara corporatlon exploitation.The difference of the present invention and domestic waste gasification and melting technology is:
(1) stalk more easily gasifies with respect to domestic waste, adds the use circle fluidized-bed gasification furnace, and gasification reaction speed height in the stove can maximize.
(2) because the hot air temperature after the preheating is higher, and the stalk species are more single, stalk is gone into stokehold drying-free processing, also need not auxiliary fuel.And the domestic waste gasification and melting has certain requirement to going into the stokehold refuse moisture, if calorific value is lower than 6000kJ/kg, must add coal or diesel oil as auxiliary fuel.
(3) in the domestic waste gasified melting system, the flying dust that the end slag that gasification furnace produces, waste heat boiler and deduster capture all need be delivered to melting furnace and carry out fusion, and among the present invention, because the stalk ash content is very low, and gasification back ash content granularity is very thin.Bed material after the gasification is gone up the part mineral matter in the enrichment stalk, only needs through behind the water logging bubble, can be again as the bed material.And the flying dust that the waste water after soaking, waste heat boiler and deduster are collected all contains the mineral matter of abundant plant growth needs, can directly impose on the farmland.
(4) among the present invention, condense on the superheater tube wall in order to control the gaseous bases slaine, water-cooling wall adds the radiant type evaporating heating surface structure of two-sided water-cooled screen around the special design of melting furnace outlet, and mainly based on following consideration: temperature drops to below the softening temperature of alkali metal salt before 1. making flue gas enter superheater; 2. arrange more radiant type evaporating heating surface, can reduce radiant type evaporating heating surface height greatly; 3. the lime-ash that condenses on the radiant type evaporating heating surface all is alkali metal salt basically, can collect lime-ash by the mechanical vibrator device.This lime-ash can be used as agricultural fertilizer.
Beneficial effect: compared with prior art, advantage of the present invention has:
(1) adopts recirculating fluidized bed low temperature gasification technology, go for stalk of any kind of and composition thereof; And the production of can maximizing, the separate unit circle fluidized-bed gasification furnace can mate with 12MW or 25MW electricity generation system.
(2) gasification product (flying dust that combustible gas, combustible gas carry, tar etc.) of gasification furnace generation directly enters melting furnace, and tar is thoroughly decomposition combustion in melting furnace, thoroughly solves the tar problem.
(3) adsorbents such as lime that add in the gasification furnace can realize that the dry method orientation removes pollutants such as sulphur, chlorine, fluorine, particularly after the degree of depth dechlorination, can prevent the high temperature corrosion of metal material, therefore can adopt conventional material to make the waste heat boiler of back, the expense of reducing investment outlay greatly, and realize efficient generating.
(4) adopt the whirlwind melting furnace, have bigger relative velocity between combustible gas, combustible granules and the combustion air, gas solid/liquid/gas reactions, gas-solid reaction are abundant, excess air coefficient can be controlled at lower level, carry out fractional combustion simultaneously, thereby significantly reduce NO
xDischarging and tail flue gas heat loss.
(5) waste water of the flying dust of waste heat boiler and deduster collection and immersion bed material all contains abundant alkali metal, and these alkali metal are that the plant growth is necessary, and directly as fertilizer sources (as potash fertilizer) imposes on the farmland.
Description of drawings
Fig. 1 is a gasifying stalk fusion generation technology schematic diagram of the present invention, wherein has: apotheca 1, disintegrating machine 2, belt pulley conveyer 3, circle fluidized-bed gasification furnace 4, screw feeder 4-1, cyclone separator 4-2, material returning device 4-3, adsorbent feed bin 4-4, air distribution plate 4-5, air compartment 4-6, vomit pipe 4-7, bosh 4-8, dragveyer 4-9, high temperature whirlwind melting furnace 5, chilling tank 5-1, waste heat boiler 6, radiant type evaporating heating surface 6-1, water-cooled tube panel 6-1-1, mechanical vibrator device 6-1-2, spiral ash ejector 6-2, superheater 6-3, economizer 6-4, air preheater 6-5, deduster 7, air-introduced machine 8, chimney 9, pressure fan 10, steam turbine generator 11.Wherein also comprise stalk a, cold air b, hot-air c, superheated steam d, bed material e, adsorbent f, waste water g, slag h, combustible gas i, high-temperature flue gas j, flying dust k.
Specific embodiments
Straw low temperature gasification melt-combustion method of the present invention is:
1) stalk carries out low temperature gasification in circle fluidized-bed gasification furnace 4, and gasification temperature is 400-650 ℃; Have a large amount of inert bed materials in the circle fluidized-bed gasification furnace 4, can heat the stalk that newly advances stove rapidly and make it reach the gasification reaction temperature, its heat accumulation function also can reduce because reinforced inhomogeneous, stalk kind and moisture change temperature fluctuation in the stove that causes.
2) circle fluidized-bed gasification furnace 4 outlets are provided with high temperature cyclone separator 4-2, to take the outer fine grained inert bed material of stove out of with combustible gas separates, again send circle fluidized-bed gasification furnace 4 back to through material returning device, in stove, form the circulation of high concentration particle material with this, its heat carrier function can make gasification furnace reach unanimity along the short transverse temperature, be beneficial to efficient dechlorination in gasifying stalk reaction, the stove, and prevent coking in the stove
3) add the lime adsorbent in circle fluidized-bed gasification furnace 4, orientation removes after the pollutants, particularly degree of depth dechlorination such as sulphur, chlorine, fluorine, can prevent the high temperature corrosion of metal material,
4) combustible gas that produces of circle fluidized-bed gasification furnace 4 carries not the carbon containing soot particle of complete reaction and enters high temperature whirlwind melting furnace 5 and carry out melt-combustion, gas residence time is 2-3s, can guarantee that carbon contained in fuel gas and the ash burns fully, ash after burning is molten condition and enters the chilling tank from the melting furnace bottom
5) high-temperature flue gas of melting furnace discharge passes through air-introduced machine 8 from chimney 9 emptyings at last successively by radiant type evaporating heating surface 6-1, superheater 6-3, economizer 6-4, air preheater 6-5, the deduster 7 of waste heat boiler 6; High temperature that waste heat boiler 6 produces or middle temperature superheated steam enter steam turbine generator 11 and generate electricity by way of merging two or more grid systems, the part vapour of an alkali metal that gasifying stalk and melt-combustion produce condenses on the radiant type evaporating heating surface 6-1 of boiler 6, through rapping and purging, a part falls into radiant type evaporating heating surface bottom ash bucket, all the other enter back-end ductwork and deduster 7 with flue gas, captured by back-end ductwork below ash bucket and deduster respectively
When 6) stalk gasifies in circle fluidized-bed gasification furnace 4, wherein contained alkali metal part can migrate to inert bed material e surface, when inert bed material e surface alkali metal content reaches finite concentration, bonding mutually will take place in inert bed material e, cause the gasification furnace fluidisation to worsen when serious, influencing gasification furnace normally moves, therefore need regular discharge section bed material e, the hott bed material e that discharges enters the bosh 4-8 of circle fluidized-bed gasification furnace 4 bottoms, can add circle fluidized-bed gasification furnace 4 as the bed material again after the regeneration of water logging bubble.
7) separated into two parts after air is preheating to 300-400 ℃ in air preheater 6-5, a part enters circle fluidized-bed gasification furnace 4, carries out gasification reaction as gasifying medium and stalk; All the other enter high temperature whirlwind melting furnace 5 as combustion air, and the carbon in fuel gas and the ash is burnt fully,
8) waste water of the flying dust of waste heat boiler 6 and deduster 7 collections and immersion bed material all contains abundant alkali metal, and these alkali metal are that the plant growth is necessary, and directly as fertilizer sources imposes on the farmland.
Stalk a comprises agricultural wastes such as cornstalk, wheat-straw, rice straw, oil crops stalk, legume crop stalk, coarse cereals crop material, cotton stalk.
Stalk in the apotheca 1 adds circle fluidized-bed gasification furnace 4 by screw feeder 4-1 after disintegrating machine 2 fragmentations, gasification temperature is 400-650 ℃.The hot-air c that adopts moisture that stalk contains and come from air preheater 6-5 is as gasifying agent, and hot-air c enters burner hearth through air compartment 4-6, air distribution plate 4-5.Air distribution plate 4-5 is a horizontal, and the centre is provided with vomit pipe 4-7.Adsorbent f among the adsorbent feed bin 4-4 adds gasification furnace 4 by material returning device 4-3, realizes pollutants such as dry removal sulphur, chlorine, fluorine.The combustible gas i that comes out in circle fluidized-bed gasification furnace 4 tops enters cyclone separator 4-2, isolates the fine grained inert bed material, and the bed material that separates reenters gasification furnace 4 by material returning device 4-3.The bed that vomit pipe 4-7 discharges is expected through behind the water logging bubble among the bosh 4-8, can expect as bed again after being pulled out by dragveyer 4-9.The combustible gas i that cyclone separator 4-2 comes out carries the carbon containing soot particle and together enters high temperature whirlwind melting furnace 5, and ignition temperature is 1000-1500 ℃, and hot-air c is from melting furnace 5 tops and tangentially enter melting furnace, realizes classification, low oxygen combustion.Slag h discharges from melting furnace 5 bottoms, behind chilling tank 5-1, pulls the back out as foundation material by dragveyer 4-9.The high-temperature flue gas j that high temperature whirlwind melting furnace 5 produces enters waste heat boiler 6, in radiant type evaporating heating surface 6-1, heat is passed to water-cooled tube panel 6-1-1, after dropping to 650-750 ℃, temperature enters superheater 6-3, can guarantee that like this alkali metal salt does not condense on superheater, can adopt conventional material to make the waste heat boiler of back.Condense in alkali metal salt on the water-cooled tube panel 6-1-1 under the effect of mechanical vibrator device 6-1-2,6-2 discharges through the spiral ash ejector.The waste water g of cooling bed material, waste heat boiler 6 and deduster 7 collected flying dust k can directly impose on the farmland owing to contain the mineral matter of abundant plant growth needs.The flue gas that superheater 6-3 comes out, pass through economizer 6-4, air preheater 6-5, deduster 7, air-introduced machine 8 successively after, finally discharge by chimney 9.The cold air b that pressure fan 10 is come is preheating to 300-400 ℃ in air preheater 6-5 after, separated into two parts, a part of hot-air c enters gasification furnace 4, and a part enters melting furnace 5.The superheated steam d that waste heat boiler 6 produces is used for steam turbine generator 11 generatings.