Dynamic measurement of liquid‐phase mass transfer coefficient and significance on the SO₂ absorption rate

Abstract

Liquid‐phase mass transfer coefficient is important for characterization of gas–liquid reactors and relevant to the modelling of gas absorption rate. Both direct and indirect methods have been used to obtain this coefficient. However, these methods have not been compared on the same basis. Liquid‐phase mass transfer coefficients were measured in three ways—(a) CO2 absorption into water, (b) SO2 absorption into 1 kmol m−3 of HCl, and (c) O2 absorption into Na2SO3—and then normalized to the coefficient for SO2. Based on transient experiments, the normalized values for liquid‐phase mass transfer coefficient obtained from three methods are in turn of kL,O2>kL,SO2>kL,CO2. The fluxes of SO2 predicted from three methods were further compared with the experimental values measured in SO2‐NaOH system. The fluxes predicted from kL,SO2 agreed well with the experimental values, whereas those from kL,CO2 and kL,O2 were significantly lower or higher. Therefore, the liquid‐phase mass transfer coefficient is preferably obtained from the targeted gas. Modelling on the flux of SO2 demonstrates the transition of controlling regions against pH. At pH above 4, the gas side resistance is larger than the liquid side, whereas at pH below 4, the gas side resistance is smaller than the liquid side.

Computational Fluid Dynamics Based Modeling of Gas Absorption Process: A State-of-the-Art Review

“…The average MTC is 0.014 cm/s for 100–1000 μm droplets with terminal velocities. This agrees well with MTCs in spray towers in the range of 0.007–0.015 cm/s …”

“…The direct way to understand the mass transfer rate is through the measurement of MTC by film theory. 367 Measured liquid-phase MTC through a two-film theory was used to investigate the effect of gas−liquid flow ratio and venturi design on gas−liquid mass transfer rates. 368 Different mass transfer models may be applicable at different positions in the same process.…”

“…This agrees well with MTCs in spray towers in the range of 0.007−0.015 cm/s. 367 4.2.2. For the Gas Bubbling System.…”

Computational Fluid Dynamics Based Modeling of Gas Absorption Process: A State-of-the-Art Review

“…The average MTC is 0.014 cm/s for 100–1000 μm droplets with terminal velocities. This agrees well with MTCs in spray towers in the range of 0.007–0.015 cm/s …”

“…The direct way to understand the mass transfer rate is through the measurement of MTC by film theory. 367 Measured liquid-phase MTC through a two-film theory was used to investigate the effect of gas−liquid flow ratio and venturi design on gas−liquid mass transfer rates. 368 Different mass transfer models may be applicable at different positions in the same process.…”

“…This agrees well with MTCs in spray towers in the range of 0.007−0.015 cm/s. 367 4.2.2. For the Gas Bubbling System.…”

Bionic Packings Enhance the Absorption of SO2 in a Bubble Column

“…Liquid side mass transfer coefficient is derived from dimensionless analysis and diffusivity correlation for gas in dilute solution . Then, according to eq , the liquid-phase mass transfer coefficient of O 2 is converted into the liquid-phase mass transfer coefficient of SO 2 Equation is as follows: k normalL , SO 2 / k normalL , normalO 2 = false( V normalO 2 / V SO 2 false) 0.4 where k L, SO 2 is the liquid-phase mass transfer coefficient of SO 2 , m/s; k L, O 2 is the liquid-phase mass transfer coefficient of O 2 , m/s; V O 2 is the molecular volume of O 2 , 25.6 cm 3 /mol; V SO 2 is the molecular volume of SO 2 , 44.8 cm 3 /mol.…”

“…39 Then, according to eq 5, the liquid-phase mass transfer coefficient of O 2 is converted into the liquid-phase mass transfer coefficient of SO 2 . 40 Equation 5 is as follows:…”

Computational Fluid Dynamics Based Modeling of Gas Absorption Process: A State-of-the-Art Review

“…The average MTC is 0.014 cm/s for 100–1000 μm droplets with terminal velocities. This agrees well with MTCs in spray towers in the range of 0.007–0.015 cm/s …”

“…The direct way to understand the mass transfer rate is through the measurement of MTC by film theory. 367 Measured liquid-phase MTC through a two-film theory was used to investigate the effect of gas−liquid flow ratio and venturi design on gas−liquid mass transfer rates. 368 Different mass transfer models may be applicable at different positions in the same process.…”

“…This agrees well with MTCs in spray towers in the range of 0.007−0.015 cm/s. 367 4.2.2. For the Gas Bubbling System.…”

Bionic Packings Enhance the Absorption of SO2 in a Bubble Column

“…Liquid side mass transfer coefficient is derived from dimensionless analysis and diffusivity correlation for gas in dilute solution . Then, according to eq , the liquid-phase mass transfer coefficient of O 2 is converted into the liquid-phase mass transfer coefficient of SO 2 Equation is as follows: k normalL , SO 2 / k normalL , normalO 2 = false( V normalO 2 / V SO 2 false) 0.4 where k L, SO 2 is the liquid-phase mass transfer coefficient of SO 2 , m/s; k L, O 2 is the liquid-phase mass transfer coefficient of O 2 , m/s; V O 2 is the molecular volume of O 2 , 25.6 cm 3 /mol; V SO 2 is the molecular volume of SO 2 , 44.8 cm 3 /mol.…”

“…39 Then, according to eq 5, the liquid-phase mass transfer coefficient of O 2 is converted into the liquid-phase mass transfer coefficient of SO 2 . 40 Equation 5 is as follows:…”

Computational Fluid Dynamics Based Modeling of Gas Absorption Process: A State-of-the-Art Review

“…The average MTC is 0.014 cm/s for 100–1000 μm droplets with terminal velocities. This agrees well with MTCs in spray towers in the range of 0.007–0.015 cm/s …”

“…The direct way to understand the mass transfer rate is through the measurement of MTC by film theory. 367 Measured liquid-phase MTC through a two-film theory was used to investigate the effect of gas−liquid flow ratio and venturi design on gas−liquid mass transfer rates. 368 Different mass transfer models may be applicable at different positions in the same process.…”

“…This agrees well with MTCs in spray towers in the range of 0.007−0.015 cm/s. 367 4.2.2. For the Gas Bubbling System.…”

Bionic Packings Enhance the Absorption of SO2 in a Bubble Column

“…Liquid side mass transfer coefficient is derived from dimensionless analysis and diffusivity correlation for gas in dilute solution . Then, according to eq , the liquid-phase mass transfer coefficient of O 2 is converted into the liquid-phase mass transfer coefficient of SO 2 Equation is as follows: k normalL , SO 2 / k normalL , normalO 2 = false( V normalO 2 / V SO 2 false) 0.4 where k L, SO 2 is the liquid-phase mass transfer coefficient of SO 2 , m/s; k L, O 2 is the liquid-phase mass transfer coefficient of O 2 , m/s; V O 2 is the molecular volume of O 2 , 25.6 cm 3 /mol; V SO 2 is the molecular volume of SO 2 , 44.8 cm 3 /mol.…”

“…39 Then, according to eq 5, the liquid-phase mass transfer coefficient of O 2 is converted into the liquid-phase mass transfer coefficient of SO 2 . 40 Equation 5 is as follows:…”