Numerical simulation of liquid spray dispersion in a fluidized bed

Pougatch, Konstantin; Salcudean, M.

doi:10.1002/cjce.20316

Cited by 9 publications

(4 citation statements)

References 13 publications

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“…The solid concentration in the lower area is higher than that in the upper area. Therefore, the collision frequency between droplets and bed material is higher when using the countercurrent spray . This leads to a higher fraction of Ca(OH) 2 particles adhering to the bed material surface.…”

Section: Resultsmentioning

confidence: 99%

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Experimental Study on In Situ Preparation of Supported Sorbent for Moderate Temperature CFB-FGD

2018

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Supported sorbent for flue gas desulfurization was prepared by a process of hydrating and drying a mixture of carrier particles and lumps of CaO in previous studies. Supported sorbent achieves high desulfurization efficiency in a Circulating Fluidized Bed (CFB) reactor at moderate temperature. However, the preparation process is complicated, which makes industrial application difficult. In this study, supported sorbent is prepared in situ in a CFB reactor by a coating process, in combination with SO2 removal. The experiments are conducted in a pilot-scale CFB experimental facility at 700–750 °C. The influence of operation parameters on supported sorbent formation and desulfurization efficiency is tested, including bed inventory, sprayer location, and spray method. The results show that the present process achieves 85.3% desulfurization efficiency with a Ca/S molar ratio of 2.01 when the bed inventory is 25 kg. This result is approximately 10 times higher than that of a zero bed inventory. The scanning electron microscope and energy dispersive spectrometer results show that the supported sorbent forms when fine Ca(OH)2 particles in the lime slurry adhere to the bed material surface. The residence time of the supported sorbent in the CFB reactor is significantly longer than that of the fine Ca(OH)2 particles. The adhesion efficiency is influenced by the spray location and spray method. The desulfurization performance of the supported sorbent prepared by the original hydration and drying method is also tested. The desulfurization efficiency is 25–35% higher than the present process because there is better adhesion in the original method than the in situ method. But the process complexity is significantly reduced when using the present process. The present process is a substantial attempt toward the application of supported sorbent.

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Section: Resultsmentioning

confidence: 99%

“…Therefore, the collision frequency between droplets and bed material is higher when using the countercurrent spray. 27 This leads to a higher fraction of Ca(OH) 2 particles adhering to the bed material surface. Hence, the average reaction time of SO 2 with Ca(OH) 2 increases when using the countercurrent spray.…”

Section: Energy and Fuelsmentioning

confidence: 99%

Experimental Study on In Situ Preparation of Supported Sorbent for Moderate Temperature CFB-FGD

2018

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“…This is due to the assumption that scaled‐down 2.2 mm spray nozzles would be used in a Fluid Coker. To obtain truly relevant values, the agglomerates produced in a smaller‐scale fluidized bed would need to be scaled‐up to match those produced with commercial‐scale nozzles in a Fluid Coker …”

Section: Resultsmentioning

confidence: 99%

Effect of interactions between spray jets on liquid distribution in a fluidized bed

et al. 2016

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In Fluid Cokers™, banks of spray nozzles are used to inject oil into a bed of hot coke particles. The purpose of this study is to determine whether interactions between spray jets could enhance liquid distribution on hot coke particles, which is crucial to improve the operability and performance of Fluid Cokers. A low temperature experimental model of Fluid Coking was used to measure the liquid distribution. Preliminary screening of nozzle positions employed conductance measurements. A binder solution was utilized to further investigate the most interesting nozzle interactions, by simulating at low temperature the formation of agglomerates during high temperature coking. Adding different dyes to the binder solutions injected by the different nozzles helped determine how nozzles interacted. With two synchronized nozzles of the same size, the liquid distribution is greatly improved when the spray jets slightly merge due to the expansion time being significantly reduced. The merged spray jets result in an unstable single jet, which allows for bubbles to be released faster from the spray jet. Because the volume of the released bubble is about the same for individual and merged jets, the jets do not contract as much upon bubble release: this enhances the jets' ability to capture gas bubbles from the bed, accelerating their expansion. Fewer agglomerates are also produced due to the improved liquid distribution.

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“…This can be achieved by confining the jet with a draft tube located downstream of the spray nozzle tip. ,− The distance from the nozzle tip should be such as to allow for sufficient particle entrainment into the jet cavity. ,, The entrainment of particles into the jet can also be improved by modifying the draft tube geometry . Although a draft tube will reduce particle entrainment into the jet, therefore increasing the average liquid content of the wet solids formed at the tip of the jet, its beneficial impact results from the reduction of variations in liquid content within the wet solids; CFD modeling confirmed that a draft tube reduces the amount of the wettest agglomerates, which are the most resistant to breakup in the fluidized bed. , Draft tubes have also been shown to improve the liquid distribution with vertical spray jets…”

Section: Reactormentioning

confidence: 99%

Review of Research Related to Fluid Cokers

Briens

McMillan

2021

Energy Fuels

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Fluid coking is a thermal conversion process that uses a conventional two-vessel circulating fluidized bed to convert heavy hydrocarbon feeds to lighter products. The technology was developed in the 1950s and since then has been used commercially around the world to upgrade heavy oils from various sources. Research work has been summarized related to all aspects of the fluid coking process, including reaction fundamentals, bed hydrodynamics, liquid distribution and jet–bed interaction, mixing of solid particles and agglomerates, mixing of vapors, control of the particle size, cleaning of the vapor stream in the scrubber, cleaning of the cold coke in the stripper, process monitoring, coke transfer lines, and the burner. The fluid coking process involves complex interactions between fluidized bed hydrodynamics, liquid feed injection, and reaction kinetics, and research tools that can take into account all of these interacting variables are requited to test methods to optimize the process. Fluid cokers can process many different types of feeds, and future applications may include blending and co-processing a variety of feedstocks ranging from waste plastics, pyrolytic bio-oil, and off-spec vegetable oils with heavy oil. The findings from this summary are also relevant for other applications that inject liquid into fluidized beds, such as the fluid catalytic cracking process, olefin polymerization cooled by liquid injection, granulators, and coaters.

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Numerical simulation of liquid spray dispersion in a fluidized bed

Cited by 9 publications

References 13 publications

Experimental Study on In Situ Preparation of Supported Sorbent for Moderate Temperature CFB-FGD

Experimental Study on In Situ Preparation of Supported Sorbent for Moderate Temperature CFB-FGD

Effect of interactions between spray jets on liquid distribution in a fluidized bed

Review of Research Related to Fluid Cokers

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