Liquid‐to‐Particle Mass Transfer in a Structured‐Bed Minireactor

Abstract

Liquid-to-particle mass transfer effects in a string pellet minireactor were studied by applying the diffusion-controlled copper dissolution technique. Structured beds were formed with cylindrical particles in spiral and vertical configurations and operated with liquid and gas-liquid feeds in upflow mode. Single-and two-phase flow experiments were conducted to study the effects of the gas and the liquid superficial velocities on the liquid-to-particle mass transfer coefficient. Computational fluid dynamics calculations were performed to study the effect of the arrangement of the particles in the reactor tube on the liquid-to-particle effective mass transfer coefficient for the single-phase flow. Correlations of the mass transfer coefficient with the operating conditions were derived.

Study of Liquid–Solid Mass Transfer and Hydrodynamics in Micropacked Bed with Gas–Liquid Flow

“…The values of the two-phase L-S volumetric mass transfer coefficient (Figure b) are lower than those in the respective single liquid phase flow (Figure b). Similar behaviour was reported by Templis and Papayannakos from the studies of L-S mass transfer in milliscale string-bed reactors (reactor diameter 2 mm; copper cylindrical particles d p = 1.5 mm) using the copper dissolution method . They attributed this to the lower wetting efficiency of the particles during the gas–liquid flow.…”

“…In conventional lab scale beds packed with cylindrical particles (3–6 mm) or spherical particles (0.54–2.4 mm), k s a was reported to be in the order of 10 –2 to 10 –1 s –1 . 14 , 17 , 18 , 60 Templis and Papayannakos 30 reported k s a on the order of 10 –2 s –1 in structured-bed minireactors formed with cylindrical particles (1.5 mm diameter). In our micropacked bed, k s a is of the order of 10 s –1 .…”

“…Similar behaviour was reported by Templis and Papayannakos from the studies of L-S mass transfer in milliscale string-bed reactors (reactor diameter 2 mm; copper cylindrical particles d p = 1.5 mm) using the copper dissolution method. 30 They attributed this to the lower wetting efficiency of the particles during the gas–liquid flow. However, they reported a small positive or negligible response of the measured two-phase L-S volumetric mass transfer coefficient to the gas velocity.…”

“…Although obtained at different velocity range and particle sizes, the measured mass transfer coefficients tended to be in agreement with the data reported by Tidona et al However, the measurement of the L-S mass transfer coefficient with G-L two-phase flow was not successful, as the electrochemical technique showed limitations. Templis and Papayannakos 30 reported the study of L-S mass transfer using the copper dissolution method in mini-string reactors formed with cylindrical particles in spiral and vertical configurations and operated with liquid-only and G-L feeds in upflow mode. The measurement of liquid-to-solid mass transfer thus remains a challenge in MPBRs.…”

Choosing the right packing in millipacked bed reactors under single phase gas flow

“…Over decades, packed bed reactors for catalyst testing have faced a reduction in size and have now diameters commonly below 1 cm, the limit being the catalyst pellet size (~1-3 mm). The advantages are the reduction of the development costs and delays: less catalyst (Moulijn et al, 2003), lower amount of feed-stock and waste (Templis and Papayannakos, 2017;Zhang et al, 2017), better temperature control (higher surface to volume ratio) (Zhang et al, 2017), easier implementation of parallel reactor systems (Moonen et al, 2017) yielding more reactors per unit area and per man-hour and reduced safety issues (Moonen et al, 2017). The experimentation performed using parallel reactor systems is known as High Throughput Experimentation (HTE).…”