内循环流化床烟气脱硫技术研究
摘要
本科题创造性地开发了内循环流化床烟气脱硫装置和技术，
旨在解决传统循环流化床在较低绝热饱和温度差运行时的湿壁和
粘壁现象、外循环量大、钙综合利用率低等问题，进一步强化了
传热、传质效果，提高钙的利用率和脱硫效率，以期促进循环流
化床烟气脱硫技术在中国的发展和应用。
实验主要分为冷态实验和热态实验两个阶段：
冷态实验装置为内径190mm有机玻璃塔，总高5.1m，主要进
行了不同塔顶、塔底结构和不同床料的流态化实验。根据观察到
的流化状态和外回流量的多少，选择塔顶结构为扩大段加挡板，
塔底为筛板式或喷流式布气结构；选择床料为40-60目或60-80
目的细砂。在表观气速为2-5m／s时，塔内固体颗粒外回流量少，
大部分颗粒都在塔内贴壁回流，流化状态好，实现了内循环流化
床的设想。实验进一步考察了表观气速、床料量等因素对塔内轴
向固含率的影响，指出在表观气速较高时塔内固含率轴向呈“C”
型分布，径向呈“环-核”流流型。
在冷态实验的基础上设计了放大的热态实验装置，其内径
300mm，总高5.3m，塔底为筛板布气，塔顶为扩大段加挡板结构，
扩大段内径480mm，高度1.1m。实验以60目-80目细砂作为主要
的惰性床料，在表观气速为2.55m／s情况下，实现了绝大部分固
体颗粒在脱硫塔内的内循环。研究了喷水量、烟气入口温度、Ca／S、
入口SO_2浓度和固体浓度等因素对脱硫效率的影响。结果表明，
绝热饱和温度差是影响脱硫效率的决定性因素，固体浓度是保证
系统稳定运行的关键因素。在Ca／S为1.2和固体浓度为10100g／m~3
等优化条件下，系统能连续稳定运行，脱硫效率达90％以上。最
后，初步建立了内循环流化床脱硫效率的预测模型。
A new technology of internally circulating fluidized bed (ICFB) for flue gas desulfurization (FGD) was developed in this study. Our research aims to solve problems of wall wetting and agglomeration , high external circulating rate and low sorbent utilization under the condition of low approach to saturation temperature in the traditional CFB-FGD technologies, to enhance the mass and heat transfer, and to increase the sorbent utilization and S02 removal efficiency, therefore to push the development and application of this technology in our country.
The experimental research includes two sections: cold condition section and hot condition section.
In the cold condition, the fluidization phenomena in the plexiglass column of 190mm in i. d, 5. 1m in height were investigated with different top and bottom structures and different kinds of bed material. According to the fluidization states observed and the external circulating rates measured, we could select a spout-fluid or orifice distributor as bottom structure, a baffleplate-equipped and expanded column as the top structure and the 40-60 mesh or 60-80 mesh sand as the suitable bed material. Therefore, an internally circulating fluidized bed in which when the superficial gas velocity was at 2-5m/s, most of particles return to the bottom section along the column wall and just a few were entrained out was developed. In additional, the effects of superficial gas velocity and the weight of bed material on the solid holdups in axial direction of the bed were discussed. The results indicate that the solid distribution present characteristics of "c" type in the
axial direction section and a "core-annulus" structure in radial under the condition of high superficial gas velocity. In the hot condition, the experimental apparatus of 300mm in i. d and 5. 3m in height was proportionally scaled up on the basis of that used in the cold condition, we could select a orifice distributor as bottom structure, a baffleplate-equipped and expanded column of 480mm in i. d, 1. 1m in height as the top structure. Most of 60-80 mesh sand used as the main bed material internally circulated when superficial gas velocity was at 2.55 m/s. In this process, effects of the factors such as the flow rate of water sprayed, inlet gas temperature, S02 inlet concentration, Ca/S ratio, solid concentration, on the efficiency of S02 removal were discussed. The experimental results show that approach to saturation temperature is the key factor on efficiency and solid concentration is the important factor that affects the stability of system. Under the condition of Ca/S of 1. 2, solid concentration of 10100g/m3 and other optimum factors, the system can continually and stably operate in long time with S02 removal efficiency above 90%. At last, a simple model was developed to predict the efficiency of S02 removal in the study.
旨在解决传统循环流化床在较低绝热饱和温度差运行时的湿壁和
粘壁现象、外循环量大、钙综合利用率低等问题，进一步强化了
传热、传质效果，提高钙的利用率和脱硫效率，以期促进循环流
化床烟气脱硫技术在中国的发展和应用。
实验主要分为冷态实验和热态实验两个阶段：
冷态实验装置为内径190mm有机玻璃塔，总高5.1m，主要进
行了不同塔顶、塔底结构和不同床料的流态化实验。根据观察到
的流化状态和外回流量的多少，选择塔顶结构为扩大段加挡板，
塔底为筛板式或喷流式布气结构；选择床料为40-60目或60-80
目的细砂。在表观气速为2-5m／s时，塔内固体颗粒外回流量少，
大部分颗粒都在塔内贴壁回流，流化状态好，实现了内循环流化
床的设想。实验进一步考察了表观气速、床料量等因素对塔内轴
向固含率的影响，指出在表观气速较高时塔内固含率轴向呈“C”
型分布，径向呈“环-核”流流型。
在冷态实验的基础上设计了放大的热态实验装置，其内径
300mm，总高5.3m，塔底为筛板布气，塔顶为扩大段加挡板结构，
扩大段内径480mm，高度1.1m。实验以60目-80目细砂作为主要
的惰性床料，在表观气速为2.55m／s情况下，实现了绝大部分固
体颗粒在脱硫塔内的内循环。研究了喷水量、烟气入口温度、Ca／S、
入口SO_2浓度和固体浓度等因素对脱硫效率的影响。结果表明，
绝热饱和温度差是影响脱硫效率的决定性因素，固体浓度是保证
系统稳定运行的关键因素。在Ca／S为1.2和固体浓度为10100g／m~3
等优化条件下，系统能连续稳定运行，脱硫效率达90％以上。最
后，初步建立了内循环流化床脱硫效率的预测模型。
A new technology of internally circulating fluidized bed (ICFB) for flue gas desulfurization (FGD) was developed in this study. Our research aims to solve problems of wall wetting and agglomeration , high external circulating rate and low sorbent utilization under the condition of low approach to saturation temperature in the traditional CFB-FGD technologies, to enhance the mass and heat transfer, and to increase the sorbent utilization and S02 removal efficiency, therefore to push the development and application of this technology in our country.
The experimental research includes two sections: cold condition section and hot condition section.
In the cold condition, the fluidization phenomena in the plexiglass column of 190mm in i. d, 5. 1m in height were investigated with different top and bottom structures and different kinds of bed material. According to the fluidization states observed and the external circulating rates measured, we could select a spout-fluid or orifice distributor as bottom structure, a baffleplate-equipped and expanded column as the top structure and the 40-60 mesh or 60-80 mesh sand as the suitable bed material. Therefore, an internally circulating fluidized bed in which when the superficial gas velocity was at 2-5m/s, most of particles return to the bottom section along the column wall and just a few were entrained out was developed. In additional, the effects of superficial gas velocity and the weight of bed material on the solid holdups in axial direction of the bed were discussed. The results indicate that the solid distribution present characteristics of "c" type in the
axial direction section and a "core-annulus" structure in radial under the condition of high superficial gas velocity. In the hot condition, the experimental apparatus of 300mm in i. d and 5. 3m in height was proportionally scaled up on the basis of that used in the cold condition, we could select a orifice distributor as bottom structure, a baffleplate-equipped and expanded column of 480mm in i. d, 1. 1m in height as the top structure. Most of 60-80 mesh sand used as the main bed material internally circulated when superficial gas velocity was at 2.55 m/s. In this process, effects of the factors such as the flow rate of water sprayed, inlet gas temperature, S02 inlet concentration, Ca/S ratio, solid concentration, on the efficiency of S02 removal were discussed. The experimental results show that approach to saturation temperature is the key factor on efficiency and solid concentration is the important factor that affects the stability of system. Under the condition of Ca/S of 1. 2, solid concentration of 10100g/m3 and other optimum factors, the system can continually and stably operate in long time with S02 removal efficiency above 90%. At last, a simple model was developed to predict the efficiency of S02 removal in the study.
引文
[1] 国家环保总局，2001年中国环境状况公报，环境工作通讯，7(2002)，5-17。
[2] 雷体钧等，中国燃煤电厂的二氧化硫排放控制，国际电力，4(1998)，57-62。
[3] 曾汉才，城市燃煤SO_2污染及其治理技术，华中电力，11(4)1998，14-19。
[4] 肖文德，吴忠泉，二氧化硫的脱除与回收，化学工业出版社，北京(2001)，1。
[5] 童志权，工业废气净化和利用，化学工业出版社，北京(2001)，6。
[6] 李宗恺等，中国的酸雨模拟及控制对策研究，气象科学，2(3)(2000)，339-347。
[7] 刘烦江，郝吉明等，酸雨二氧化硫污染控制战略，中国环境科学，16(3)(1996)，108-112。
[8] Takeshita M, FGD performance and experience on coal-fired plants, London, IEA coal research, 1993, 35-38.
[9] Uchida S, Ariga O, Absorption of sulfur dioxide into limstone slurry in a stirred tank, Can J Chem Eng, 46(1985), 2281-2291.
[10] Olausson S, Wallin M, A model for the absorption of sulphur dioxide into a limestone slurry, Chem Eng J, 15 (1993), 99-105.
[11] Rochelle G T, King C J, The effect of additives on mass transger in CaCO_3 or CaO slurry scrubbing of SO_2 from waster gas, Ind Chem Fundam, 16(1)(1997),67-75.
[12] Meierer, Matthias, Operation and optimization of flue gas desulfurization systems in coal-fired power plants, Power-plant Chem, 1(3)(1999),12-17.
[13] Ellison W, Today' s FGD system satisfy retrofit needs for 19905, Power, 135(10) 1991,101-106.
[14] 吴忠标，大气污染控制工程，化学工业出版社，北京(2001)，323。
[15] 郝吉明，陆永琪，燃煤二氧化硫控制技术现状及技术经济分析，中国环保产业，(2)(1998)，28-31。
[16] 管菊根，喷雾干燥烟气脱硫工艺，电力环境保护，15(3)(1999)，59-62。
[17] 邰德荣等，电子束烟气脱硫技术示范工程进展，环境科学进展，7(2)(1997)，125-135。
[18] 徐息等，电子束脱硫技术的应用及分析，电力环境保护，15(1)(1995)，1-5。
[19] Gerald H, Newton, John kramlich, modeling the SO_2-slurry droplet reaction, AIChE Journal, 36(12) (1990), 1865-1872.
[20] Dantuluri SR, Mathematical model of sulfur dioxide absorption into a calcium hydroxide slurry in a spray dryer, Separation Science and Tech, 25(13) (1990), 1843-1855.
[21] Joson Makani, CFB technology injects life into dry scrubbing, Power, 137(10)(1993),79-81.
[22] Tom Ohmacher et al, Circulating dry scrubber with debuts new unit, Power, 139(4)(1995),88-91.
[23] XiaoXun Ma et al, Use of limestone for SO_2 removal from flue gas in the semidry FGD process with a powder-particle spouted bed. Chemical Engineering Science, 55 (2000), 4643-4652.
[24] Karsten Felsvang, Peter Bo olsen, The GSA dry scrubbing technology forretrofit applications, Environmental Progress, 18(2)(1995), 75-79.
[25] 黄震，65t／h锅炉循环流化床烟气脱硫系统及经济技术分析，环境工程，18(2)(1998)，40-42。
[26] 谢建军等，循环流化床烟气脱硫研究进展，重庆环境科学，23(1)(2001)，31-33。
[27] 米浩林，马国骏，回流式烟气循环流化床脱硫技术，热力发电，(2)(1998)，57-61。
[28] 张伟，张凡，杨霓云，半干半湿烟气脱硫反应塔湿壁现象的分析．环境科学研究，13(2)(2000)，62-64。
[29] 彭斌等，循环流化床烟气脱硫模拟中试实验研究，东南大学学报，31(2)(2001)，72-76。
[30] 张学才等，中小型锅炉烟气气流喷雾干燥法脱硫的研究，环境工程，17(4)(1999)，50-52。
[31] 朱廷钰，肖云汉，循环流化床流体动力学研究进展，热能动力工程，16(1)2000，11-15。
[32] Yang Y, Local slip behavior in the circulating fluidized bed, AIChE Symp Ser, 89(1993),80-90.
[33] 白丁荣等，循环流态化：(Ⅵ)反应器行为及其模型，化学反应工程与工艺，8(3)(1992)，258-263。
[34] 金涌，祝金旭等，流态化工程原理，清华大学出版社(2001)，21-27。
[35] Mastellone, Maria Laura, Umberto Arena, Effect of particle size and density on solids distribution along the riser of a circulating fluidized bed Chem. Eng. Sic, 54(22) (1999), 5383-5391.
[36] Nethery James K, Model for flue gas desulfurization in a circulating fluidized dry scrubber, AIChE J, 42(1) (1996), 259-268.
[2] 雷体钧等，中国燃煤电厂的二氧化硫排放控制，国际电力，4(1998)，57-62。
[3] 曾汉才，城市燃煤SO_2污染及其治理技术，华中电力，11(4)1998，14-19。
[4] 肖文德，吴忠泉，二氧化硫的脱除与回收，化学工业出版社，北京(2001)，1。
[5] 童志权，工业废气净化和利用，化学工业出版社，北京(2001)，6。
[6] 李宗恺等，中国的酸雨模拟及控制对策研究，气象科学，2(3)(2000)，339-347。
[7] 刘烦江，郝吉明等，酸雨二氧化硫污染控制战略，中国环境科学，16(3)(1996)，108-112。
[8] Takeshita M, FGD performance and experience on coal-fired plants, London, IEA coal research, 1993, 35-38.
[9] Uchida S, Ariga O, Absorption of sulfur dioxide into limstone slurry in a stirred tank, Can J Chem Eng, 46(1985), 2281-2291.
[10] Olausson S, Wallin M, A model for the absorption of sulphur dioxide into a limestone slurry, Chem Eng J, 15 (1993), 99-105.
[11] Rochelle G T, King C J, The effect of additives on mass transger in CaCO_3 or CaO slurry scrubbing of SO_2 from waster gas, Ind Chem Fundam, 16(1)(1997),67-75.
[12] Meierer, Matthias, Operation and optimization of flue gas desulfurization systems in coal-fired power plants, Power-plant Chem, 1(3)(1999),12-17.
[13] Ellison W, Today' s FGD system satisfy retrofit needs for 19905, Power, 135(10) 1991,101-106.
[14] 吴忠标，大气污染控制工程，化学工业出版社，北京(2001)，323。
[15] 郝吉明，陆永琪，燃煤二氧化硫控制技术现状及技术经济分析，中国环保产业，(2)(1998)，28-31。
[16] 管菊根，喷雾干燥烟气脱硫工艺，电力环境保护，15(3)(1999)，59-62。
[17] 邰德荣等，电子束烟气脱硫技术示范工程进展，环境科学进展，7(2)(1997)，125-135。
[18] 徐息等，电子束脱硫技术的应用及分析，电力环境保护，15(1)(1995)，1-5。
[19] Gerald H, Newton, John kramlich, modeling the SO_2-slurry droplet reaction, AIChE Journal, 36(12) (1990), 1865-1872.
[20] Dantuluri SR, Mathematical model of sulfur dioxide absorption into a calcium hydroxide slurry in a spray dryer, Separation Science and Tech, 25(13) (1990), 1843-1855.
[21] Joson Makani, CFB technology injects life into dry scrubbing, Power, 137(10)(1993),79-81.
[22] Tom Ohmacher et al, Circulating dry scrubber with debuts new unit, Power, 139(4)(1995),88-91.
[23] XiaoXun Ma et al, Use of limestone for SO_2 removal from flue gas in the semidry FGD process with a powder-particle spouted bed. Chemical Engineering Science, 55 (2000), 4643-4652.
[24] Karsten Felsvang, Peter Bo olsen, The GSA dry scrubbing technology forretrofit applications, Environmental Progress, 18(2)(1995), 75-79.
[25] 黄震，65t／h锅炉循环流化床烟气脱硫系统及经济技术分析，环境工程，18(2)(1998)，40-42。
[26] 谢建军等，循环流化床烟气脱硫研究进展，重庆环境科学，23(1)(2001)，31-33。
[27] 米浩林，马国骏，回流式烟气循环流化床脱硫技术，热力发电，(2)(1998)，57-61。
[28] 张伟，张凡，杨霓云，半干半湿烟气脱硫反应塔湿壁现象的分析．环境科学研究，13(2)(2000)，62-64。
[29] 彭斌等，循环流化床烟气脱硫模拟中试实验研究，东南大学学报，31(2)(2001)，72-76。
[30] 张学才等，中小型锅炉烟气气流喷雾干燥法脱硫的研究，环境工程，17(4)(1999)，50-52。
[31] 朱廷钰，肖云汉，循环流化床流体动力学研究进展，热能动力工程，16(1)2000，11-15。
[32] Yang Y, Local slip behavior in the circulating fluidized bed, AIChE Symp Ser, 89(1993),80-90.
[33] 白丁荣等，循环流态化：(Ⅵ)反应器行为及其模型，化学反应工程与工艺，8(3)(1992)，258-263。
[34] 金涌，祝金旭等，流态化工程原理，清华大学出版社(2001)，21-27。
[35] Mastellone, Maria Laura, Umberto Arena, Effect of particle size and density on solids distribution along the riser of a circulating fluidized bed Chem. Eng. Sic, 54(22) (1999), 5383-5391.
[36] Nethery James K, Model for flue gas desulfurization in a circulating fluidized dry scrubber, AIChE J, 42(1) (1996), 259-268.