Study On The Combustion And Pollutant Emission Characteristics Of Biomass And Coal Blends In A Circulating Fluidized Bed

Energy is an important substantial foundation of human's survival and development.It is the motive power of human being engaging in various economic activities.With the development of the social economy,the energy sources consumption is increasing quickly,but the energy shortage in all over the world is facing great challenge at present time.At the same time,the gas pollution caused by coal utilization is endangering the safety of resource, development of the social economy and human survival seriously.Facing this critical situation,new kinds of energy must be exploited and used to reduce or replace the application of fossil fuel.As a kind of renewable energy,biomass energy has great practical value.The co-combustion with coal is one of easy, simple and economical methods in using biomass,but its utilization is facing many difficulties and challenges.So,to survey the critical fluidization velocity of the blendings of coal and biomass,to probe separation discipline of oxysulfide and nitrogen oxide in the circulating fluid bed,to control pollutant discharge,to realize highly active cleanse combustion of coal is significant meaning to actual production.First of all,coal and biomass distribution of particle size on the determination of the minimum fluidizing velocity of the test method,and the minimum fluidizing velocity of the test stand measuring lean coal blending ratio in all the minimum fluidizing velocity.Experiment materials include:chaff and lean coal were depleted to 0%,5%,10%,20%,40%,80%,100%of the mixing ratio of blending.Coal obtained from the formula of the minimum fluidizing velocity,return binding assay of the chaff of the minimum fluidizing rate of relational,thus obtained two-component mixed system of minimum fluidizing velocity,amend the two-component minimum fluidizing velocity of the formula for calculating U_mf=1.2x_lu_p+u_s(1.05-1.2x_l).Two-component hybrid systems for the minimum fluidizing velocity of the calculation formula provides a theoretical and experimental data.Next,pollution testing that the matter having carried out a life on system drifts along when coal burns in circulating fluid bed discharges an experiment,the effects of temperature and mixing ratio of the mixed oxides of sulfur coal combustion characteristics of precipitation.Compared with the single-quality coal,biomass of very small volume of SO₂ concentration,when the combustion temperature exceeds 800℃,the coal and biomass combustion volume of SO₂ concentration has increased faster.With the accession to the amount of chaff increased the volume of the combustion generated volume of SO₂ concentration,in the blending ratio of biomass in the 0%to 10%of the volume between the concentration of SO₂ fell a very sharp,quality of coal from a single down to 550μl/l at the time of 200μl/l.10%to 20%between the second,fell toμl/lppm fromμl/lppm.20%to 100%of the volume of SO₂ concentrations decline very slowly,drop from 100μl/l to 70μl/l.Adding too much biomass for control of SO₂ emissions would not be of much significance.With the increase in combustion temperature SO₂ emissions have increased.And after blended with 10%of the biomass,at 650℃to 850℃between the increase of SO₂ emissions from the more gentle,from 200μl/l to 300μl/l,at 850℃to 950℃between the rapid increase from 300μl/l to 400μl/l.SO₂ emissions and mixing of what the relationship between biomass is not very clear.It can be said to control the emissions of SO₂,the key is the control of combustion temperature,the most suitable combustion temperature is between the 800℃to 850℃.At last,in the experiment of discharging pollutants,the effects of temperature and mixing ratio of the mixed coal combustion nitrogen oxides precipitation characteristics.Lean coal and biomass combustion,respectively, with an increase in combustion temperature of the volume of NO_X concentration increase.With the accession to the increase in biomass,combustion-generated NO_X concentration decreased volume.As biomass and coal to reduce the increase in the proportion,in the blending ratio of biomass in the 0%to 10%of the volume between the concentration of NO_X very sharp decline,dropped from 190μl/l to 100μl/l,10%to 20%between the second,dropped from 100μl/l to 70μl/l,20%to 100%of the volume between the concentration of NO_X relatively slow decline,dropped from 70μl/l to 30μl/l.The addition of biomass in coal combustion can significantly reduce NO_X emissions,and biomass with the increase in the proportion,reduce NO_X emissions was gradually getting smaller.It can be said that too many of the chaff for the control of NO_X emissions would not be of much significance.With the increase in combustion temperature generated by the corresponding increase in nitrogen oxides,mixing 10%of the mixed biomass burning coal at 650℃to 800℃between the nitrogen oxides emissions of the more moderate increase in,increased by approximately 25μl/l of NO_X,After 800℃the rapid increase in,an increase of 40μl/l of NO_X.20%of chaff combustion mixing and combustion of coal blending 10%chaff coal nitrogen oxides emitted to the small,but it is not particularly evident.Anyway,when the combustion temperature exceeds 800℃,the NO_X emissions increased significantly accelerated.Certain go into the main body of a book has been carried out on mixed coal with biomass in circulating fluid bed combustion process middle sulfur nitrogen oxide characteristic property discharging and the critical fluidization velocity,to expect that the data and theory enriching and accumulating the valuable experiment in should study a field study a conclusion,be that reasonableness design,fabrication,economy and clean operation burning the boiler using mixed coal with biomass provide the reference basis.