Influence of the Model Scale on Hydrodynamic Scaling in CFB Boilers

Mirek, Paweł

doi:10.1590/0104-6632.20160334s20150348

Cited by 11 publications

(6 citation statements)

References 14 publications

(14 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The scale-up of cyclones is important for reactor design and estimating separation efficiency. Mirek P. (2016Mirek P. ( , 2018 investigated the scaling rules of cyclones in CFB boilers and estimated the separation efficiency of cyclones by setting up the following model (Eqs. (16)-(21)).…”

Section: Scale-up Methodology and Grade Efficiencymentioning

confidence: 99%

Recent Progress in Efficient Gas–Solid Cyclone Separators with a High Solids Loading for Large-scale Fluidized Beds

Fushimi

Yato

Sakai

et al. 2021

KONA

View full text Add to dashboard Cite

Circulating fluidized beds (CFB)s are important technical equipment to treat gas-solid systems for fluid catalytic cracking, combustion, gasification, and high-temperature heat receiving because their mass and heat transfer rates are large. Cyclones are important devices to control the performance of CFBs and ensure their stable operation; heat-carrying and/or solid catalyst particles being circulated in a CFB should be efficiently separated from gas at a reduced pressure loss during separation. In commercial CFBs, a large amount of solids (> 1 kg-solid (m 3-gas)-1 or > 1 kg-solid (kg-gas)-1) is circulated and should be treated. Thus, gas-solid cyclones with a high solids loading should be developed. A large number of reports have been published on gas-solid separators, including cyclones. In addition, computational fluid dynamics (CFD) technology has rapidly developed in the past decade. Based on these observations, in this review, we summarize the recent progress in experimental and CFD studies on gassolid cyclones. The modified pressure drop model, scale-up methodology, and criteria for a single large cyclone vs. multiple cyclones are explained. Future research perspectives are also discussed.

show abstract

Section: Scale-up Methodology and Grade Efficiencymentioning

confidence: 99%

Recent Progress in Efficient Gas–Solid Cyclone Separators with a High Solids Loading for Large-scale Fluidized Beds

Fushimi

Yato

Sakai

et al. 2021

KONA

View full text Add to dashboard Cite

show abstract

“…The entrained solids are assumed to flow at their slip velocity, u s = u–u t , with u t being the single particle terminal velocity (calculated according to), and form a transport zone that extends up to the riser top and that shows a constant net back-mixing from the core to the wall layers. This back-mixing is governed by a mass transfer coefficient, k , computed from measurements in large-scale units under a wide range of operational conditions and boiler geometries, ,,,,− as shown in eq . This back-mixing yields an exponential decay with a decay constant K (linked to k according to eq , see ref ).…”

Section: Description Of the Modelmentioning

confidence: 99%

Dynamic Modeling of the Reactive Side in Large-Scale Fluidized Bed Boilers

Castilla

Montañés

Pallarès

et al. 2021

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

This work presents a dynamic model of the reactive side of large-scale fluidized bed (FB) boilers that describes the infurnace transient operation of both bubbling and circulating FB boilers (BFB and CFB, respectively). The model solves the dynamic mass and energy balances accounting for the bulk solids, several gas species, and the fuel phase. The model uses semiempirical expressions to describe the fluid dynamics, fuel conversion, and heat transfer to the furnace walls, as derived from units other than the studied ones. The model is validated against operational data from two different industrial units: an 80 MW CFB and a 130 MW BFB, both at steady-state and transient conditions. The validated model is used to analyze: (i) the performance of the reactive side of two FB boilers under offdesign, steady-state conditions of operation; and (ii) the open-loop transient response when varying load or fuel moisture. The results underline the key role of heat capacity on the stabilization time. Within a given unit, the differences in heat capacity between the top and bottom of the furnace affect also the stabilization times, with the furnace top (lower heat capacity) being 1−3 times faster in the CFB unit and up to 10 times faster in the BFB unit. Due to the differences in gas velocity, the investigated boilers are found to stabilize more rapidly to input changes when running at full load than at partial load. Lastly, a variable ramping rate analysis shows that the inherent transient responses of the reactive side disappear when disturbances are introduced at (slower) rates, typical of industrial operation. Thus, the reactive side could be modeled as pseudo-static.

show abstract

“…However, due to the complexity of the heterogeneous gas-solid system, its behavior depending on numerous boundary conditions (e.g., gas velocity and solid flux), the utilized particle system, reactor size, and geometry, etc. [26][27][28][29][30][31], accurate a priori assertions on the system's performance under novel boundary conditions remains a challenge. Although several studies have formulated semi-empirical sets of equations for modeling of fluidized beds [32][33][34][35][36][37][38], their application generally is only valid for a given range of boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

System Hydrodynamics of a 1 MWth Dual Circulating Fluidized Bed Chemical Looping Gasifier

et al. 2023

View full text Add to dashboard Cite

Chemical looping gasification (CLG) is a novel dual-fluidized bed gasification technology that allows for the production of high-calorific syngas from various solid feedstocks (e.g., biomass). Solid circulation between the two coupled fluidized bed reactors, serving the purpose of heat and oxygen transport, is a key parameter for the CLG technology, making system hydrodynamics the backbone of the gasification process. This study serves the purpose to provide holistic insights into the hydrodynamic behavior of the dual-fluidized bed reactor system. Here, special focus is placed on the operational principles of the setup as well as the entrainment from the circulating fluidized bed (CFB) reactors, the latter being the driving force for the solid circulation inside the entire reactor system. Using an elaborate dataset of over 130 operating periods from a cold flow model and 70 operating periods from a 1 MWth CLG pilot plant, a holistic set of ground rules for the operation of the reactor setup is presented. Moreover, a novel easily-applicable approach, solely relying on readily-available live data, is presented and validated using data from the 1 MWth chemical looping gasifier. Thereby, a straightforward estimation of solid entrainment from any CFB setup is facilitated, thus closing a crucial research gap.

show abstract

Influence of the Model Scale on Hydrodynamic Scaling in CFB Boilers

Cited by 11 publications

References 14 publications

Recent Progress in Efficient Gas–Solid Cyclone Separators with a High Solids Loading for Large-scale Fluidized Beds

Recent Progress in Efficient Gas–Solid Cyclone Separators with a High Solids Loading for Large-scale Fluidized Beds

Dynamic Modeling of the Reactive Side in Large-Scale Fluidized Bed Boilers

System Hydrodynamics of a 1 MWth Dual Circulating Fluidized Bed Chemical Looping Gasifier

Contact Info

Product

Resources

About