?72?r?7.3?10pA,Pa单位Kpa,催化剂直径高A5,某催化反应在500℃,本征动力学方程
度均为5MM,密度0.8G/CM,A分压10.133,De=0.025CM3/S。计算效率因子。
解:
计算以浓度为变量的反应速率常数2(?rA)(?rA)?p=7.3?10?7(RT)2cAV?k?7.3?10?7?p(RT)2?7.3?10?7?0.8??8.314??273?500???2.412?10?7cm3.mol?1.s?1计算西勒模数2?VS2pAS2?10.1334==0.833cm f'?cAS??2cAS???3.153?106mol.cm?3SS0.5?0.5?+2?0.52RT8314?(273?500)4V?S?SSSk2.412?10?7f'?cAS??0.833?3.153?10?6?4.60De0.025?1?11???????0.20164.6tanh(3?4.63?4.6??????0.52?0.5计算效率因子?=1?11???S?tanh?3?S?3?S
6.常压下正丁烷在镍铝催化剂上进行脱氢反应。已知该反应为一级不可逆反应。在500℃时,反应的速率常数为k=0.94cm3s-1gcat-1,若采用直径为0.32cm的球形催化剂,其平均孔径d0=1.1╳10-8m,孔容为0.35cm3g-1,空隙率为0.36,曲折因子等于2.0。试计算催化剂的效率因子。 解:
?P??PVg?0.36?1.029g?cm?30.35T773.15?4850?1.1?10?6?M58kV?k?P?0.94?1.029?0.9673s?1DK?4850?d0?0.01948cm2s?1D?0.01948?0.36De?KP??0.003506cm2s?1?2?S?R3kV0.160.9673??0.8859De30.003506?1?e3?0.8859?e?3?0.88591?????3?0.8859?3?0.8859? 0.8859?e?e3?0.8859??1?14.2634?0.07011????0.8859?14.2634?0.07012.6577??0.7052?7.相对分子质量120某组分,该组分催化剂表面的浓度1.0?10mol/cm,实测反应速率
?531.2?10?5mol/cm3.s,催化剂直径0.2cm球体,孔隙率0.5,曲折因子3,孔径3?10?9m,
求效率因子。 解:
由于孔径很小,设想为克努森扩散(1)计算有效扩散系数De DK?4850?3?10?7De?DK273?6002?1cm.s?3.342?10?3cm2.s?1120?P0.5?3.342?10?3??5.57?10?4cm2.s?1?3f?cAS?cAS(2)设本征动力学方程(-rA)?kf?cA?,由于f?cA??f?cAS???cA?cAS?f'?cAS?cA?0时,f?cA?=0 f'?cAS?=222-rfc?????RkR????ASAS2?S=???故?-rA?S=9DecAS?S?9DecAS?3?DecAS?R?宏观动力学方程(?RA)???-rA?S????9DecAS?S???R?2R2?-RA?S0.121.2?10?5??????2.394?4?59DecAS95.57?10?1?102S?11?由效率因子与?S关系可知??=?S????2.394 ?S?2.7273tanh3?3??S?S??2S试差法求得??1?11?????0.3218?S?tanh?3?S?3?S?
第八章 气液反应动力 1.已知气液相反应A?B?R,
r??rA?20CACbmol/(cme.s)含A10%,?=3,?=0.15,D=2.2?10?5, KA?1.115?10-4,kAL?0.07,cb?3,单位容积床层宏观反应速率。
解:
液相中B组分浓度大,视为常数,本征速率将是拟一级反应?rA?20CACb=20?0.003CA=0.06CAmol/(cm3.s)计算?值kDALcBL?=?kAL20?3.0?10?3?2.2?10?5?0.0164?0.02属于慢反应,?=10.07-RA?kAL?(CAI?CAL)?(1??G)kCAICBLCAI?CAL?pApy202.6?0.1?1?6?3?A?mol.L?1.818?10mol.cmKAKA1.115?104CAI1?(1??G)kcBLkAL??1.818?10?61?(1?0.15)?20?0.0030.03?3?1.462?10?6mol.cm?3-RA?kAL?(CAI?CAL)?0.07?3?(1.818?1.462)?10?6?7.467?10?5mol.L?1.s?1
2.若采用NaOH水吸收CO2. 25度,(1)纯水,气液膜阻力比(2)(3)
kAG?0.789,KAL?25,KA?3039.9,DAL?DBL,
PCO2?1.0133KPa,CNAOH?2mol/L吸收速率
PCO2?20.244KPa,CNAOH?0.2mol/L,吸收速率
解:
1k(1)AGKAKAL1?0.7893039.925?1:96传质为液膜控制,可忽略气膜传质阻力及浓度差PAG=PAL(2)?A??1,?B??20CBL??BkAGDAL?20.789DALPAG????1.0133?0.064mol/L?CBL?AkALDBL?125DBL反应面与相界面重合???,CAL=0KA111??? KG?KAGKGKAG?KALKAG(?RA)?KG(PAG?KACAL)?KGPAG?0.789?1.0133?0.8mol/(m2..h)0(3)CBL??BkAGDAL?20.789PAG???20.244?1.278mol/L?CBL?AkALDBL?125相界面与反应面不重合,反应在液膜内,CAL=0CAI=PAI20.244?DC?1?0.2??0.00666mol/l ?=1+ABLBL?1??16KA3039.9?BDALCAL?2?0.00666KA1113039.9???? KG?0.1128mol/(h.m2.kpa)KGKAG?KAL0.78916?25(?RA)?KG(PAG?KACAL)?0.1128?20.244?2.283mol/(m2.h)
3氨与硫酸的反应飞速不可逆
NH3(A),H2SO4(B),(NH4)2SO4(R)
KAG?3.45?10?3kmol.m?2.s?1.kpa?1,KAL?0.005,HA?0.74,DAL?DBL
(1)氨分压6.08kpa,硫酸浓度是0.4kmol/l,总反应速率。 (2)硫酸浓度3kmol/l,求速率。 解;
(1)由反应式知:?A??1,?B??0.5,反应是飞速瞬时反应?BkAGDAL13.45?10?3?6.08C?PAG=?=2.10kmol/l?AkALDBL20.005?DC0CBL?0.4kmol/l?CBL 则?=1+ABLBL CAI?HAPA?0.74?6.08?4.50kmol/l?BDALCAL0BL?10.41?11???2?1??1?0.5??1.04 -RA???PA????6.08?0.011kmol.m.h??3?4.5KHK?3.45?100.74?0.005?1.04??AAL??AG0(2)CBL?3kmol/l?CBL ,????1?1?RA?kAGPA?3.45?10?3?6.08?0.21kmol.m?2.h?1
4.在填料塔中用浓度为0.25mol·L-1的甲胺水溶液来吸收气体中的H2S,反应式如下:
H2S+RNH2→HS-+RNH3+ (A) (B) (R) (S)
反应可按瞬间不可逆反应处理,在20℃时的数据如下:F=3╳10-3mol·cm-2s-1;cT=55.5mol·L-1;pT=101.3kPa; kALσ=0.03s-1;kAGσ=5.92╳10-7mol·cm-3kPa-1s-1;DAL=1.5
-52-1-52-1
╳10cms;DBL=1╳10cms;HA=11.65kPa·L·mol-1。为使气体中H2S浓度由1╳10-3降到1╳10-6,求最小液气比和所需填料高度。 解:
FpA2?pA1p?LcA2?cA1cT3?10?3?1?10?3?1?10?6??L??0.25?0??55.5??L?6.65?10?4最小液气比??L?6.65?10?4?F????3?0.22min3?10c0????B??kAG??DAL?BL????A?????k?AL?????D?BL??pAG????5.92?10?7??1.5?10?5???0.03???????1?10?5???103?101.3?3?10?6mol?cm?3?3?10?3kmol?m?3cBL?0.25kmol?m?3c0BL?cBL???pAi?0KAG??kAG?Z?F?pA1dpAFpApkAG?pp?ln2
A2ApkAG?pA1?3?10?3101.33?5.92?10?7ln10?310?6?230.37cm5.在一逆流操作的填料塔把有害A含量从0.1%降到0.02%。
?KAG?0.3158 ?KAL?0.11 HA?12.67 L=700 F=100 P=101.3
(1)总浓度56kmol/l的水,球填料高度。(2)高浓度kAL?KBL,?A?1,?B??1
解
B0.8kmol/l,
:
(1)对塔顶和塔内某一界面物料衡算p?pA1c?cFA?LATA1pcp?101.3?0.0002c?0100?A?700A 7.895?10?2pA?1.6?10?3?cA101.356?选择几个pA,计算cA,利用亨利定律求出与之平衡p?A,算出推动力pA-pA1KAG??1kAG??HA112.67???129.9 KAG??7.698?10?3kmol.m?3.Kpa?1.h?1kAL?0.31580.1FdYA?FdpAF?KAG?(pA?p?A)dz Z=ppK??p1pA2dpA100?p?p?101.3?7.698?10?3?0.10130.02027dpA?513mp?p?AGAA(2)由物料衡算FpA?pA1p?LcA?cA1Lp700101.3cT pA?pA1=Fc(cB1?cB)??(0.8?cB2)T10056p10.133?101.3?0.001A?10.133?12.666cB2则cB2?12.666?0.7920kmol/lcBL?c0BL的瞬间反应???,pAL=0,KAG??kAG?Z?F?p1dpAFpA2?100pKAG?p?0.3158ln(1?10?3?101.3?A2p?pK??2?10?4?101.3???5.03mAAG?lnpA1101.3?
AA