Gas phase dispersion/mixing investigation in a representative geometry of gas-liquid upflow Moving Bed Hydrotreater Reactor (MBR) using developed gas tracer technique and method based on convolution/regression

Alexander, Vineet; Albazzaz, Hamza; Al‐Dahhan, Muthanna H.

doi:10.1016/j.ces.2018.10.013

Cited by 8 publications

(12 citation statements)

References 25 publications

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“…The tapped bed height was 13 cm thermal heat capacity, which facilitates differentiating tracer gas and carrier gas. 12,[27][28][29] For small systems, like micro-channel reactors, inlet and outlet geometries contribute to the spread in the RTD curve while, according to this study, He will reduce the spread. To adequately identify tailing requires a delta-pulse rather than a step-input function.…”

Section: Tracermentioning

confidence: 70%

“…12 Furthermore, our data advocates that researchers establish independently the extent of the interaction between the tracer and solids phase rather than assuming that it is inert: 30 we clearly show that at ambient temperature CO 2 adsorbs to the catalyst surface. Helium might be an adequate tracer for gas-liquid(water) and gas-liquid-solid systems 29 as we would expect little adsorption in liquid (water) but a better system would include helium and another nonadsorbing gas like nitrogen or argon whose gas diffusivity characterizes the actual system physico-chemical properties better.…”

Section: Tracermentioning

confidence: 99%

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Fluidized bed hydrodynamic modeling of CO₂ in syngas: Distorted RTD curves due to adsorption on FCC

2021

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Bubbles rising through fluidized beds at velocities several times superficial velocities contribute to solids backmixing. In micro-fluidized beds, the walls constrain bubble sizes and velocities. To evaluate gas-phase hydrodynamics and identify diffusional contributions to longitudinal dispersion, we injected a mixture of H 2 , CH 4 , CO, and CO 2 (syngas) as a bolus into a fluidized bed of porous fluid catalytic cracking catalyst while a mass-spectrometer monitored the effluent gas concentrations at 2 Hz. The CH 4 , CO, and CO 2 trailing RTD traces were elongated versus H 2 demonstrating a chromatographic effect. An axial dispersion model accounted for 92% of the variance but including diffusional resistance between the bulk gas and catalyst pores and adsorption explained 98.6% of the variability. At 300 C, the CO 2 tailing disappeared consistent with expectations in chromatography (no adsorption). H 2 and He are poor gas-phase tracers at ambient temperature. We recommend measuring RTD at operating conditions.

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Section: Tracermentioning

confidence: 70%

Section: Tracermentioning

confidence: 99%

Fluidized bed hydrodynamic modeling of CO₂ in syngas: Distorted RTD curves due to adsorption on FCC

2021

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“…At these conditions, the catalyst bed behaves as an upflow packed bed with slight expansion at the top of the reactor. [ 2 ] This study's primary focus is to understand the local phase saturations, local velocities, local backmixing, and local maldistribution at various locations inside the catalyst bed, and to identify its relationship with the design of the reactor. Hence, different local measurement zones are selected at various radial and axial locations along the catalyst bed's packed region, as shown in Figure 1 and Table 1.…”

Section: Methodsmentioning

confidence: 99%

“…[ 1 ] Upflow moving‐bed hydrotreater (MBR) reactors represent a new technology for hydrotreating and are usually used as guard reactors to fixed‐bed residual desulfurization (RDS) reactors. [ 2 ] The MBR reactor has a hydrodemetallization catalyst (HDM), which treats crude oil in the presence of hydrogen for metal and organometallic removal.…”

Section: Introductionmentioning

confidence: 99%

Local hydrodynamics investigation of industrial scaled‐down upflow moving‐bed hydrotreater reactor using a two‐tip optical probe

2021

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Upflow moving‐bed hydrotreater (MBR) is used in refineries as a guard reactor to a fixed‐bed residual desulfurization reactor. Uniform local flow distribution in these reactors is critical to avoid issues like coking, catalyst agglomeration, and hotspots in the catalyst bed. Local maldistribution is investigated on a scaled‐down MBR at a scaled‐down industrial flow condition using an experimental technique called two‐tip optical probe (TTOP), which gives local phase saturations, phase velocities, backmixing, and maldistribution at voids of a two‐phase‐flow packed bed. TTOP implemented at local radial/axial locations indicates highly fluctuating phase saturations inside the catalyst bed, with zones having low‐to‐high gas or liquid saturations, indicating severe local maldistribution. The local phase backmixing and local maldistribution is more on the upper part of the bed.

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“…Gas transfer occurs due to gas transfer from the gas phase to the liquid phase or preferably where there are three phenomena (Alexander et al, 2019)…”

Section: Literature Reviewmentioning

confidence: 99%

The Effect of Salinity on Oxygen Transfer Process in Leachate With a Low Initial Cod Concentration

Sagara¹,

Sari²,

Septiariva³

et al. 2022

JGST

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Leachate is one of the results of rainwater infiltration and the degradation of microorganisms in waste. Some leachate types usually contain salinity which is an inhibitor in biological treatment processes. Aerobic biological treatment usually also requires sufficient dissolved oxygen (DO) levels. This study aimed to determine the effect of salinity on oxygen transfer in saline leachate. This study used a DO meter to measure the DO concentration in the 2 L volume reactor. There were two variations, namely leachate without salinity and with salinity 6 ppt, where the processing was carried out with three repetitions. The final oxygen transfer coefficients for the leachate without salinity and with salinity were 0.021 and 0.014, respectively. While the detention time required for leachate without salinity is 47.5 minutes, it takes 71.43 minutes with salinity.

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Gas phase dispersion/mixing investigation in a representative geometry of gas-liquid upflow Moving Bed Hydrotreater Reactor (MBR) using developed gas tracer technique and method based on convolution/regression

Cited by 8 publications

References 25 publications

Fluidized bed hydrodynamic modeling of CO₂ in syngas: Distorted RTD curves due to adsorption on FCC

Fluidized bed hydrodynamic modeling of CO₂ in syngas: Distorted RTD curves due to adsorption on FCC

Local hydrodynamics investigation of industrial scaled‐down upflow moving‐bed hydrotreater reactor using a two‐tip optical probe

The Effect of Salinity on Oxygen Transfer Process in Leachate With a Low Initial Cod Concentration

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Gas phase dispersion/mixing investigation in a representative geometry of gas-liquid upflow Moving Bed Hydrotreater Reactor (MBR) using developed gas tracer technique and method based on convolution/regression

Cited by 8 publications

References 25 publications

Fluidized bed hydrodynamic modeling of CO2 in syngas: Distorted RTD curves due to adsorption on FCC

Fluidized bed hydrodynamic modeling of CO2 in syngas: Distorted RTD curves due to adsorption on FCC

Local hydrodynamics investigation of industrial scaled‐down upflow moving‐bed hydrotreater reactor using a two‐tip optical probe

The Effect of Salinity on Oxygen Transfer Process in Leachate With a Low Initial Cod Concentration

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Fluidized bed hydrodynamic modeling of CO₂ in syngas: Distorted RTD curves due to adsorption on FCC

Fluidized bed hydrodynamic modeling of CO₂ in syngas: Distorted RTD curves due to adsorption on FCC