水煤浆螺旋折流板预热器的流体力学和传热性能的数值模拟
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摘要
有研究表明对入炉前的水煤浆进行预热可以提高其气化效率,今利用数值模拟方法,采用非牛顿流体Bingham模型,计算并比较螺旋折流板换热器和弓形折流板换热器预热水煤浆时的流动换热性能。研究螺旋折流板换热器用于水煤浆预热的可行性以及螺旋角、搭接度对其流动换热性能的影响。结果表明:以单位压降的温升作为流动换热综合性能评价指标,螺旋折流板换热器更适于预热水煤浆。对螺旋折流板换热器,螺旋角和搭接度的变化对壳侧温升影响不大,而螺旋角的增大或搭接度减小能使壳侧压降明显降低。大螺旋角和小搭接度的换热器用于水煤浆预热时的流动换热性能更好。在螺旋角18°～40°、搭接度0%～50%,40°螺旋角,0%搭接度的螺旋折流板换热器的流动换热性能最好。研究结果可为选择水煤浆预热器的型式和结构参数提供参考。
Preheating of coal water slurry(CWS) before entering into gasifier can improve its gasification efficiency. Bingham model was used to calculate and compare flow and heat transfer performance of shell-and-tube heat exchangers with helical baffles(STHXsHB) and shell-and-tube heat exchangers with segmental baffles(STHXsSB) for CWS preheating. The feasibility of using STHXsHB to preheat CWS and effects of helical angle and overlapped degree on flow and heat transfer were studied. The results show that STHXsHB is more suitable for preheating CWS when the temperature difference per unit pressure drop is used as an evaluation criterion. Temperature difference has little variation with helical angle and overlapped degree, but pressure drop decreases significantly with the increase of helical angle or the decrease of overlapped degree for STHXsHB. STHXsHB shows better flow and heat transfer performance with larger helical angles and smaller overlapped degrees. The shell-and-tube heat exchanger with 40° helical angle and 0% overlapped degree is the best. The results can help to select type and structural parameters of CWS preheaters.
Preheating of coal water slurry(CWS) before entering into gasifier can improve its gasification efficiency. Bingham model was used to calculate and compare flow and heat transfer performance of shell-and-tube heat exchangers with helical baffles(STHXsHB) and shell-and-tube heat exchangers with segmental baffles(STHXsSB) for CWS preheating. The feasibility of using STHXsHB to preheat CWS and effects of helical angle and overlapped degree on flow and heat transfer were studied. The results show that STHXsHB is more suitable for preheating CWS when the temperature difference per unit pressure drop is used as an evaluation criterion. Temperature difference has little variation with helical angle and overlapped degree, but pressure drop decreases significantly with the increase of helical angle or the decrease of overlapped degree for STHXsHB. STHXsHB shows better flow and heat transfer performance with larger helical angles and smaller overlapped degrees. The shell-and-tube heat exchanger with 40° helical angle and 0% overlapped degree is the best. The results can help to select type and structural parameters of CWS preheaters.
引文
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[2]高聚忠.煤气化技术的应用与发展[J].洁净煤技术,2013,19(1):65-71.GAO J Z.Application and development of coal gasification technologies.Clean Coal Technology,2013,19(1):65-71.
[3]孙漾,顾幸生.水煤浆气化装置操作优化技术及其应用[J].化工学报,2012,63(9):2799-2804.SUN Y,GU X S.Coal water slurry gasification unit operation optimization technology and its application[J].CIESC Journal,2012,63(9):2799-2804.
[4]夏德宏,唐献红,王世均.水煤浆预热对燃烧的影响[J].冶金能源,1992(5):30-31.XIA D H,TANG X H,WANG S J.Influence of preheating on CWS combustion[J].Energy for Metallurgical Industry,1992,11(5):30-31.
[5]AIUCHI K,MORIYAMA R,TAKEDA S,et al.A pre-heating vaporization technology of coal-water-slurry for the gasification process[J].Fuel Processing Technology,2007,88(4):325-331.
[6]ZHANG J,ZHOU Z,MA L,et al.Efficiency of wet feed IGCC(integrated gasification combined cycle)systems with coal-water slurry preheating vaporization technology[J].Energy,2013,51(1):137-145.
[7]CRESPí-LLORENS D,VICENTE P,VIEDMA A.Flow pattern of non-Newtonian fluids in reciprocating scraped surface heat exchangers[J].Experimental Thermal&Fluid Science,2016,76(9):306-323.
[8]CRESPí-LLORENS D,VICENTE P,VIEDMA A.Experimental study of heat transfer to non-Newtonian fluids inside a scraped surface heat exchanger using a generalization method[J].International Journal of Heat and Mass Transfer,2018,118(3):75-87.
[9]HE Z,FANG X,ZHANG Z,et al.Numerical investigation on performance comparison of non-Newtonian fluid flow in vertical heat exchangers combined helical baffle with elliptic and circular tubes[J].Applied Thermal Engineering,2016,100(3):84-97.
[10]RIOS-IRIBE E Y,CERVANTES-GAXIOLA M E,RUBIO-CASTRO E,et al.Heat transfer analysis of a non-Newtonian fluid flowing through a Plate Heat Exchanger using CFD[J].Applied Thermal Engineering,2016,101(3):262-272.
[11]WANG Q,ZENG M,MA T,et al.Recent development and application of several high-efficiency surface heat exchangers for energy conversion and utilization[J].Applied Energy,2014,135(12):748-777.
[12]王斯民,肖娟,王家瑞,等.基于流固耦合理论的螺旋折流板换热器结构优化研究[J].高校化学工程学报,2017,31(3):539-546.WANG S M,XIAO J,WANG J R,et al.Structural optimization of shell-tube heat exchanger with helical baffles based on fluid-structure interaction[J].Journal of Chemical Engineering of Chinese Universities,2017,31(3):539-546.
[13]WEN J,YANG H Z,WANG S M,et al.Experimental investigation on performance comparison for shell-and-tube heat exchangers with different baffles[J].International Journal of Heat&Mass Transfer,2015,84(5):990-997.
[14]TAHER F N,MOVASSAG S Z,RAZMI K,et al.Baffle space impact on the performance of helical baffle shell and tube heat exchangers[J].Applied Thermal Engineering,2012,44(11):143-149.
[15]DU T T,DU W H,CHE K,et al.Parametric optimization of overlapped helical baffled heat exchangers by Taguchi method[J].Applied Thermal Engineering,2015,85(6):334-339.
[16]WEN J,YANG H Z,JIAN G P,et al.Energy and cost optimization of shell and tube heat exchanger with helical baffles using Kriging metamodel based on MOGA[J].International Journal of Heat and Mass Transfer,2016,98(7):29-39.
[17]谢东.水煤浆流变特性及其检测技术研究[D].武汉:华中科技大学,2010.XIE D.Research on rheological characteristics of coal water slurry and its measurement technologies[D].Wuhan:Huazhong University of Science and Technology,2010.
[18]代淑兰,陈良勇,代少辉.水煤浆的流变特性研究进展[J].锅炉技术,2010,41(3):76-80.DAI S L,CHEN L Y,DAI S H.Advances in research on rheological behaviour of coal-water slurries[J].Boiler Technology,2010,41(3):76-80.
[19]ZHANG J F,LI B,HUANG W J,et al.Experimental performance comparison of shell-side heat transfer for shell-and-tube heat exchangers with middle-overlapped helical baffles and segmental baffles[J].Chemical Engineering Science,2009,64(8):1643-1653.
[20]LEI Y G,HE Y L,CHU P,et al.Design and optimization of heat exchangers with helical baffles[J].Chemical Engineering Science,2008,63(17):4386-4395.
[21]王斯民,王萌萌,顾昕,等.基于火积理论的螺旋折流板换热器结构优化[J].高校化学工程学报,2016,30(3):532-539.WANG S M,WANG M M,GU X,et al.Structure optimization of helical baffle heat exchangers using entransy theory[J].Journal of Chemical Engineering of Chinese Universities,2016,30(3):532-539.
[22]RIOS-IRIBE E Y,CERVANTES-GAXIOLA M E,RUBIO-CASTRO E,et al.Heat transfer analysis of a non-Newtonian fluid flowing through a plate heat exchanger using CFD[J].Applied Thermal Engineering,2015,84(6):225-236.
[23]HUGHES W F,BRIGHTON J A.Schaum's outline of theory and problems of fluid dynamics[M].New York:McGraw-Hill,1967.
[24]岑可法,姚强,曹欣玉,等.煤浆燃烧、流动、传热和气化的理论与应用技术M].杭州:浙江大学出版社,1997.CEN K F,YAO Q,CAO X Y,et al.Theoru and application of combustion,flow,heat transfer,gasfication of coal slurry[M].Hangzhou:Zhejiang University press,1997.
[25]赵碧,蔡京荣.水煤浆加压气化技术工艺特点及应用[J].氮肥技术,2017,38(5):8-12.ZHAO B,CAI J R.Characteristics and application of the technology of coal-water slurry pressurized gasification[J].DANFEIJISHU,2017,38(5):8-12.
[26]王斯民,王萌萌,顾昕,等.螺旋折流板换热器结构参数多目标优化的数值模拟[J].西安交通大学学报,2015,49(11):14-19,109.WANG S M,WANG M M,GU X,et al.Multi-objective optimization on the structural parameters of shell-and-tube heat exchanger with helical baffles[J].Journal of Xi'an Jiaotong University,2015,49(11):14-19,109.