污泥煤粉混合制浆及浆体燃烧特性的试验研究
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摘要
污泥是污水处理过程中的必然产物,其含有大量的有害物质,如不对其进行妥善处理必然引起严重的二次污染。目前的处理方式中,焚烧最为有效和洁净。污泥煤粉混烧克服了污泥低热值,高含水无法满足自身水分蒸发的难题。但由于污泥的粘度很高,所制混浆难以达到泵送和雾化要求。本文通过对污泥微观结构的观察,分析了污泥粘度高的原因;研究了物理化学方法的降粘机理;提出了一种制备污泥浆体燃料的方法。研究结果如下:
污泥结构分析表明:污泥的基本结构为丝状微生物相互缠绕、搭接所形成的网状结构,自身排泄物EPS(胞外聚合物)与水形成凝胶体,填充在网状结构中。导致污泥粘度很高。
物理作用方式会破坏污泥网状结构,降低污泥粘度。挤压方式的降粘效果最为明显,最终粘度值可降低到2.64Pa·S,降粘率达到83.66%。化学方法可以破坏微生物细胞壁,放出细胞水,降低污泥粘度。其中添加5%NaOH,污泥粘度值可降低到0.73Pa·S,降粘率达到96.23%。
污泥中掺加煤粉制浆,当煤粉添加量超过40%时,浆体粘度明显上升,说明煤粉添加量控制在40%以内比较合理。
污泥中加入10%的煤粉制成的浆体,其热值足以满足水份蒸发的需要,且燃烧过程能够稳定进行。添加40%煤粉,混浆热值能够达到1.38×10~4kJ/kg,相当于劣质煤的发热量。
混浆中添加碱,对污泥的燃烧过程影响很小,着火温度略有升高,燃烬温度变化也不大,说明在混浆中加碱降粘燃烧是可行的。
Sludge is the inevitable product of the sewage disposal process. If not properly handled, large amounts of harmful substances in sludge can inevitably cause secondary serious pollution. Combustion is the most efficient and cleanest way in the current disposal approach. Combustion of Sludge and pulverized coal mixture can overcome the sludge’s low calorific value and the problem that high water content can’t meet the need of its own water evaporation. However, due to the high viscosity of the sludge, the slurry is difficult to meet the viscosity requirements of pumping and?atomization. Based on the observation of microstructure of sludge, this paper analyzes the causes of sludge’s high viscosity, studies viscosity-reduction mechanism by use of physical and chemical methods, and proposes a method of preparing sludge slurry fuel. The results are as follows:
The structure analysis shows that basic structure of sludge is a network structure formed by overlapping and entangling of filamentous microorganisms. Their own waste EPS (extracellular polymer) dissolved in water to form gels, together filling in the network structure, which leads to high viscosity of sludge.
Physical forces will damage sludge’s network structure and reduce sludge viscosity. The compressing method has the maximal viscosity reduction effect, the final viscosity can reach 2.64Pa·S, viscosity reduction rate 83.66%. Chemical methods can damage the cell walls of microorganisms, release cell water and thus reduce sludge viscosity. Add 5% NaOH, sludge viscosity value can reach 0.73Pa·S, viscosity reduction rate 96.23%.
Add pulverized coal to sludge to make slurry. When the amount of pulverized coal are above 40% , the slurry viscosity obviously rises. It shows that adding less than 40% of pulverized coal is reasonable.
Add 10% of pulverized coal to sludge to make slurry, heat of the slurry can meet the needs of the water evaporation and the combustion process can proceed steadily. Add 40% of pulverized coal, slurry heat value can reach 1.38×10~4mJ / g, equivalent to heat of low quality coal;
Adding alkali to the slurry has little effect on sludge combustion process, ignition temperature increased slightly, and burnout temperature did not change much, indicating that viscosity reduction combustion is feasible when adding alkali to the slurry.
污泥结构分析表明:污泥的基本结构为丝状微生物相互缠绕、搭接所形成的网状结构,自身排泄物EPS(胞外聚合物)与水形成凝胶体,填充在网状结构中。导致污泥粘度很高。
物理作用方式会破坏污泥网状结构,降低污泥粘度。挤压方式的降粘效果最为明显,最终粘度值可降低到2.64Pa·S,降粘率达到83.66%。化学方法可以破坏微生物细胞壁,放出细胞水,降低污泥粘度。其中添加5%NaOH,污泥粘度值可降低到0.73Pa·S,降粘率达到96.23%。
污泥中掺加煤粉制浆,当煤粉添加量超过40%时,浆体粘度明显上升,说明煤粉添加量控制在40%以内比较合理。
污泥中加入10%的煤粉制成的浆体,其热值足以满足水份蒸发的需要,且燃烧过程能够稳定进行。添加40%煤粉,混浆热值能够达到1.38×10~4kJ/kg,相当于劣质煤的发热量。
混浆中添加碱,对污泥的燃烧过程影响很小,着火温度略有升高,燃烬温度变化也不大,说明在混浆中加碱降粘燃烧是可行的。
Sludge is the inevitable product of the sewage disposal process. If not properly handled, large amounts of harmful substances in sludge can inevitably cause secondary serious pollution. Combustion is the most efficient and cleanest way in the current disposal approach. Combustion of Sludge and pulverized coal mixture can overcome the sludge’s low calorific value and the problem that high water content can’t meet the need of its own water evaporation. However, due to the high viscosity of the sludge, the slurry is difficult to meet the viscosity requirements of pumping and?atomization. Based on the observation of microstructure of sludge, this paper analyzes the causes of sludge’s high viscosity, studies viscosity-reduction mechanism by use of physical and chemical methods, and proposes a method of preparing sludge slurry fuel. The results are as follows:
The structure analysis shows that basic structure of sludge is a network structure formed by overlapping and entangling of filamentous microorganisms. Their own waste EPS (extracellular polymer) dissolved in water to form gels, together filling in the network structure, which leads to high viscosity of sludge.
Physical forces will damage sludge’s network structure and reduce sludge viscosity. The compressing method has the maximal viscosity reduction effect, the final viscosity can reach 2.64Pa·S, viscosity reduction rate 83.66%. Chemical methods can damage the cell walls of microorganisms, release cell water and thus reduce sludge viscosity. Add 5% NaOH, sludge viscosity value can reach 0.73Pa·S, viscosity reduction rate 96.23%.
Add pulverized coal to sludge to make slurry. When the amount of pulverized coal are above 40% , the slurry viscosity obviously rises. It shows that adding less than 40% of pulverized coal is reasonable.
Add 10% of pulverized coal to sludge to make slurry, heat of the slurry can meet the needs of the water evaporation and the combustion process can proceed steadily. Add 40% of pulverized coal, slurry heat value can reach 1.38×10~4mJ / g, equivalent to heat of low quality coal;
Adding alkali to the slurry has little effect on sludge combustion process, ignition temperature increased slightly, and burnout temperature did not change much, indicating that viscosity reduction combustion is feasible when adding alkali to the slurry.
引文
[1]E.Nwyenys , J.Baeyens , R.Dewil , et al.Advanced Sludge Treatment affects Extracellular Polymeric Substances to Improve Activated Sludge Dewatering[J]. J.Hazard.Mat.2004,106B:83-92.
[2]V.Urbain,J.C.Block,and J.Manem,Bioflocculation in activated sludge:an analytic approach[J].Water Research,1993,27,829-838.
[3]J.W.Costerton,G.G.Geesey,K.J.Cheng.How Bacteria Stick[J].Sci Am,1978,238 (1):86 ~95.
[4]M.F.Dignac and V.Urbain et al.Chemical description of extracellular polymers:Implication on activated sludge floc structure[J].Water Sci.Technol , 1998 ,8(38):45-53.
[5]J.Wingender,T.R.New,Flemming H C,et al.Microbial Extracellular Plymeric Substances: Characterization,Structure and Function[M].Berlin:Springer,1999.
[6]K.Keiding,and P.H.Nielsen,Desorption of organic macromolecules from activated sludge: effect of ionic composition.Water Resource,1997(31):1665-1672.
[7]Hong Liu,Herbert H,P.Fang.Extraction of extracellular polymeric subatance(sEPS)ofsludges.Journal of Biotechnology,2002:249~256.
[8]周健,龙腾锐,苗利利.胞外聚合物EPS对活性污泥沉降性能的影响研究[J].环境科学报,2004,24(4):613-618.
[9]Fr?lund B O,et al.Enzymatic activaties in the activated sludge floc matrix.Appl.Microbiol.Biotechnol,1995(43):755-761.
[10]Liu Y,Fang H H P.Influences of extracellular polymeric substances(EPS)on flocculation,settling,and dewateringof activated sludge[J].Water Sci Technol, 2003, 33(3):237-273.
[11]Morgan J W,Forster C F,Evison L.A comparative study of the nature of biopolymers extracted from anaerobic and activated sludges.Water Res, 1990, 24:743–750.
[12]Sutherland I W.Exopolysaccharides in bioflims flocs and related structures.Water Sci Technol,2001,43,77-86.
[13]B.Q.Liao,D.G.Allen,I.G.Droppo,et al.Surface properties of sludge and their role in bioflocculation and settleability[J].Water Research,2001,35:339-350.
[14]Geesey G.G. Microbial exopolymers:ecological and economic economic considerations [J] ASM News,1982,48:9-14.
[15]HsiehK.M.,Murgel G.A.,Lion L.w.,Shuler M.L.interactions of mierobial biofilms with toxic trace metals:1.Observation and modeling of cell growth,attachment,and production of extracellular polymer[J]Biotechnol.Bioeng.,1994,44(2):219-231.
[16]Nielsen P.H.,Jahn A.,Palmgren R. Conceptual model for production and composition of exopolymers in biofilms[J].water sci.Technol.,1997,36(1):11-19
[17]Nieklin J.,Graeme-Cook K.,Killington R.著;林稚兰译.微生物学(第2版)[M]北京:科学出版社,2004:94.
[18]LaspidouC.S , RittmanLn B.E. A unified theory for extracellular polymeric substances,soluble microbial products,and active and inert biomass[J].Water Res.,2002,36:2711-2720.
[19]王红武,李晓岩,赵庆祥.胞外聚合物对活性污泥沉降和絮凝性能的影响研究[J].中国安全科学学报,2003,13(9):32-34
[20]Namkung E.Rittmann B.E.Soluble microbial products (SMP)formation kinetic by biofilms [J].Water Res.,1986,20(6):795-806.
[21]Forster,C.J.Activated sludge surfaces inrelation to the sludge volume index [J].Water Res.,1971,5:861-870.
[22]Brown M.J.,Lester J.N. Comparison of baeterial extraeellular polyer extraction methods[J].Appl. Environ. Microbiol.. 1980,40 (2) :179-185.
[23]霍贞,王芬,季民.污泥破解技术的研究与进展.工业水处理,2005,25(9)
[24]Chio H B, Hwang K Y, Shin E B. Effect on anaerobic digestion of sewage sludge pretreatment[ J] . Wat. Sci. Tech., 1997, 35( 10) : 207 -211
[25] Muller J. Disintegration as a key-step in sewage sludge treatment [ J] . Wat. Sci.
[26]Camacho P, Deleris S. A comparative study between mechanical,thermal and oxidative disintegration techniques of waste activated sludge[ J] . Wat. Sci. Tech., 2002, 46( 10) : 79 - 87
[27]Sakai Y, Fukase T. An activated sludge process without excess sludge production[ J] . Wat. Sci. Tech., 1997, 36( 11) : 163– 170
[28]Deleris S, Rouston J M. Effect of ozonation on activated sludge solubilization and mineralization [ J] . Ozone Sci. Eng., 2000, 22( 2) : 473– 486
[29]Saby S, Djafer M, Chen G H. Feasibility of using a chlorination step to reduce excess sludge in activated sludge process[ J] . Water Res., 2002, 36( 5) : 656 - 666
[30]林志高,张守中.废弃活性污泥加碱预处理后厌氧消化的试验研究[J].给水排水,1997,23(1):10–15
[31]Daud,W.R.W.Fluidized Bed Dryers-Recent Advances[J]. Advanced Powder Technology , 2008 . 19 (5). 403-418
[32]李伟东等.改性污泥与无烟煤成浆性的研究[J].燃料化学学报,2009,37(1)36-30
[33]朱妙军.污泥水煤浆的成浆、燃烧及燃烬特性特性研究[D].浙江大学,2008
[34]李明,李伟东,李伟峰等.污泥与石油焦的共成浆性[J].石油学报,2008,24(6):663-668
[35]王丹.污泥水煤浆的基础特性、脱硫特性以及锅炉燃烧特性研究[D].杭州:浙江大学,2010
[36]王惠桐.污泥煤浆的最佳浓度、流变特性与稳定特性研究[D].杭州:江苏大学,2009
[37]顾利锋,陈晓平,赵长遂等、城市污泥和煤混燃特性的热重分析法研究[J].热能动力工程,2003,18(6):561-563
[38] Ndaji F E,Ellyat W A T,Malik A A,et al.Temperature Programmed combustion studies of the co-proeessing of coal and waste materials[J].Fuel , 1999 ,78(3):301-307
[39]Otero M,Diez C,Calvo L F,et a1.Analysis of the co-combustion of sewage sludge and coal by TG-MS[J].Biomass Bioenergy,2002,22(4):319-329
[40]张云都,喻剑辉,郭建全等,煤与城市污泥混燃的热重法研究[J]煤炭转化,2005,28(2):67-71
[41]李东鹏,高洪培,循环流化床条件下贫煤掺烧高水分污泥的燃烧特性试验研究[J]洁净煤技术,2006,12(2):56-59
[42]吕清刚,李志伟,那永洁,等CFBC混烧城市污泥与煤:N2O与NO的排放[J].工程热物理学报,2004,25(I):163-166.
[43]陈晓平,顾利锋,赵长遂等城市污泥与煤混烧过程中NOx和N2O的排放特性[J].东南大学学报(自然科学版).2005,350):122-125.
[44]刘渊源.城市污水污泥在流化床中的焚烧特性及重金属排放特性研究[D]杭州:浙江大学,2004.
[45]B Lecknera,Amanda L-E,Luckeb K,et al.Gaseous emissions from co-combustion of sewage sludge and coal/wood in a fluidized bed[J].Fuel,2004,83:477-486.
[46]L-E Amand,B Lecker Metal Emissions from co-combustion of Sewage Sludge and coal/wood in a fluidized bed[J].Fuel,2004,83:1803-1821.
[47]M B Folgueras,Diaz R M,Xiberta J.Sulphur retention during co-combustion of coal and sewage sludge[J].Fuel,2004,83:1315-1322.
[48]吕清刚等.城市下水污泥和煤/LPG在循环流化床上的混烧试验研究[J].工程热物理学报,2006,27(2):339-342
[2]V.Urbain,J.C.Block,and J.Manem,Bioflocculation in activated sludge:an analytic approach[J].Water Research,1993,27,829-838.
[3]J.W.Costerton,G.G.Geesey,K.J.Cheng.How Bacteria Stick[J].Sci Am,1978,238 (1):86 ~95.
[4]M.F.Dignac and V.Urbain et al.Chemical description of extracellular polymers:Implication on activated sludge floc structure[J].Water Sci.Technol , 1998 ,8(38):45-53.
[5]J.Wingender,T.R.New,Flemming H C,et al.Microbial Extracellular Plymeric Substances: Characterization,Structure and Function[M].Berlin:Springer,1999.
[6]K.Keiding,and P.H.Nielsen,Desorption of organic macromolecules from activated sludge: effect of ionic composition.Water Resource,1997(31):1665-1672.
[7]Hong Liu,Herbert H,P.Fang.Extraction of extracellular polymeric subatance(sEPS)ofsludges.Journal of Biotechnology,2002:249~256.
[8]周健,龙腾锐,苗利利.胞外聚合物EPS对活性污泥沉降性能的影响研究[J].环境科学报,2004,24(4):613-618.
[9]Fr?lund B O,et al.Enzymatic activaties in the activated sludge floc matrix.Appl.Microbiol.Biotechnol,1995(43):755-761.
[10]Liu Y,Fang H H P.Influences of extracellular polymeric substances(EPS)on flocculation,settling,and dewateringof activated sludge[J].Water Sci Technol, 2003, 33(3):237-273.
[11]Morgan J W,Forster C F,Evison L.A comparative study of the nature of biopolymers extracted from anaerobic and activated sludges.Water Res, 1990, 24:743–750.
[12]Sutherland I W.Exopolysaccharides in bioflims flocs and related structures.Water Sci Technol,2001,43,77-86.
[13]B.Q.Liao,D.G.Allen,I.G.Droppo,et al.Surface properties of sludge and their role in bioflocculation and settleability[J].Water Research,2001,35:339-350.
[14]Geesey G.G. Microbial exopolymers:ecological and economic economic considerations [J] ASM News,1982,48:9-14.
[15]HsiehK.M.,Murgel G.A.,Lion L.w.,Shuler M.L.interactions of mierobial biofilms with toxic trace metals:1.Observation and modeling of cell growth,attachment,and production of extracellular polymer[J]Biotechnol.Bioeng.,1994,44(2):219-231.
[16]Nielsen P.H.,Jahn A.,Palmgren R. Conceptual model for production and composition of exopolymers in biofilms[J].water sci.Technol.,1997,36(1):11-19
[17]Nieklin J.,Graeme-Cook K.,Killington R.著;林稚兰译.微生物学(第2版)[M]北京:科学出版社,2004:94.
[18]LaspidouC.S , RittmanLn B.E. A unified theory for extracellular polymeric substances,soluble microbial products,and active and inert biomass[J].Water Res.,2002,36:2711-2720.
[19]王红武,李晓岩,赵庆祥.胞外聚合物对活性污泥沉降和絮凝性能的影响研究[J].中国安全科学学报,2003,13(9):32-34
[20]Namkung E.Rittmann B.E.Soluble microbial products (SMP)formation kinetic by biofilms [J].Water Res.,1986,20(6):795-806.
[21]Forster,C.J.Activated sludge surfaces inrelation to the sludge volume index [J].Water Res.,1971,5:861-870.
[22]Brown M.J.,Lester J.N. Comparison of baeterial extraeellular polyer extraction methods[J].Appl. Environ. Microbiol.. 1980,40 (2) :179-185.
[23]霍贞,王芬,季民.污泥破解技术的研究与进展.工业水处理,2005,25(9)
[24]Chio H B, Hwang K Y, Shin E B. Effect on anaerobic digestion of sewage sludge pretreatment[ J] . Wat. Sci. Tech., 1997, 35( 10) : 207 -211
[25] Muller J. Disintegration as a key-step in sewage sludge treatment [ J] . Wat. Sci.
[26]Camacho P, Deleris S. A comparative study between mechanical,thermal and oxidative disintegration techniques of waste activated sludge[ J] . Wat. Sci. Tech., 2002, 46( 10) : 79 - 87
[27]Sakai Y, Fukase T. An activated sludge process without excess sludge production[ J] . Wat. Sci. Tech., 1997, 36( 11) : 163– 170
[28]Deleris S, Rouston J M. Effect of ozonation on activated sludge solubilization and mineralization [ J] . Ozone Sci. Eng., 2000, 22( 2) : 473– 486
[29]Saby S, Djafer M, Chen G H. Feasibility of using a chlorination step to reduce excess sludge in activated sludge process[ J] . Water Res., 2002, 36( 5) : 656 - 666
[30]林志高,张守中.废弃活性污泥加碱预处理后厌氧消化的试验研究[J].给水排水,1997,23(1):10–15
[31]Daud,W.R.W.Fluidized Bed Dryers-Recent Advances[J]. Advanced Powder Technology , 2008 . 19 (5). 403-418
[32]李伟东等.改性污泥与无烟煤成浆性的研究[J].燃料化学学报,2009,37(1)36-30
[33]朱妙军.污泥水煤浆的成浆、燃烧及燃烬特性特性研究[D].浙江大学,2008
[34]李明,李伟东,李伟峰等.污泥与石油焦的共成浆性[J].石油学报,2008,24(6):663-668
[35]王丹.污泥水煤浆的基础特性、脱硫特性以及锅炉燃烧特性研究[D].杭州:浙江大学,2010
[36]王惠桐.污泥煤浆的最佳浓度、流变特性与稳定特性研究[D].杭州:江苏大学,2009
[37]顾利锋,陈晓平,赵长遂等、城市污泥和煤混燃特性的热重分析法研究[J].热能动力工程,2003,18(6):561-563
[38] Ndaji F E,Ellyat W A T,Malik A A,et al.Temperature Programmed combustion studies of the co-proeessing of coal and waste materials[J].Fuel , 1999 ,78(3):301-307
[39]Otero M,Diez C,Calvo L F,et a1.Analysis of the co-combustion of sewage sludge and coal by TG-MS[J].Biomass Bioenergy,2002,22(4):319-329
[40]张云都,喻剑辉,郭建全等,煤与城市污泥混燃的热重法研究[J]煤炭转化,2005,28(2):67-71
[41]李东鹏,高洪培,循环流化床条件下贫煤掺烧高水分污泥的燃烧特性试验研究[J]洁净煤技术,2006,12(2):56-59
[42]吕清刚,李志伟,那永洁,等CFBC混烧城市污泥与煤:N2O与NO的排放[J].工程热物理学报,2004,25(I):163-166.
[43]陈晓平,顾利锋,赵长遂等城市污泥与煤混烧过程中NOx和N2O的排放特性[J].东南大学学报(自然科学版).2005,350):122-125.
[44]刘渊源.城市污水污泥在流化床中的焚烧特性及重金属排放特性研究[D]杭州:浙江大学,2004.
[45]B Lecknera,Amanda L-E,Luckeb K,et al.Gaseous emissions from co-combustion of sewage sludge and coal/wood in a fluidized bed[J].Fuel,2004,83:477-486.
[46]L-E Amand,B Lecker Metal Emissions from co-combustion of Sewage Sludge and coal/wood in a fluidized bed[J].Fuel,2004,83:1803-1821.
[47]M B Folgueras,Diaz R M,Xiberta J.Sulphur retention during co-combustion of coal and sewage sludge[J].Fuel,2004,83:1315-1322.
[48]吕清刚等.城市下水污泥和煤/LPG在循环流化床上的混烧试验研究[J].工程热物理学报,2006,27(2):339-342