Chemical Engineering Commons^™

Evolution Of Fcc - Past Present And Future And The Challenges Of Operating A High Temperature Cfb System, Ye-Mon Chen

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

The fluid catalytic cracking (FCC) process is one of the most important circulating fluidized bed processes. Although the FCC process has been in commercial operation for over 60 years, the technology continues to evolve in order to meet new challenges, which include processing more difficult feedstock and meeting more stringent environmental regulations. This paper presents selected snap-shots of a few challenges (high temperature erosion, corrosion and emission control) that the FCC process faces today and the new challenges yet to come in the near future.

Catalyst Attrition In The Cfb Riser, Andreas Thon, Marvin Kramp, Ernst-Ulrich Hartge, Stefan Heinrich, Joachim Werther

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

Catalyst attrition in the CFB riser was experimentally investigated in a pilot scale CFB system consisting of a 400 mm diameter riser with a height of 15 m, a return leg and a two-stage cyclone separation. The catalyst loss of the CFB system was measured. In order to discern between attrition occurring in the cyclones and in the riser the system was simulated by a population balance approach which takes the separation efficiency of the cyclone system into account. On the basis of the experimental investigation an empirical correlation for catalyst attrition in the CFB riser has been developed which …

The Relationship Between Fluidization Velocity And Segregation In Two-Component Fluidized Beds: A Preliminary Analysis, Brunello Formisani, Rossella Girimonte, Vincenzino Vivacqua

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

Experiments are presented that provide the initial and final fluidization velocity of binary mixtures at varying composition. Introducing just one parameter to account for their segregation level, the theoretical equations of the two characteristic velocities are derived. These equations are then employed to predict the concentration profile obtained by slowly defluidizing the bed down to the fixed state

Coal Ignition Temperature In Oxygen-Enriched Cfb Boiler, Junnan Chao, Hairui Yang, Junfu Lv, Hai Zhang, Qing Liu, Yuxin Wu

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

The oxygen-enriched Circulating fluidized bed (CFB) combustion technology is a new method to reduce CO2 emissions. The coal ignition temperature, Ti F, in an oxygen-enriched CFB boiler is an important parameter for designing the startup burner and for choosing the operating strategy during the startup process. The combustion of five types of coal under four different atmospheres (air, O2 27 %, O2 40%, O2 53%, CO2 as balance gas) was measured in a laboratory scale fluidized bed (FB) with an under-bed preheat system. Using thermocouples and a Gas Analyzer, the changes in bed temperature and the concentration of the different …

Effect Of Bed Temperature, Fuel Density And Particle Size On Hydrodynamic Parameters Of 10 Mw Fluidized Bed Combustion Power Plant Using Riser Waste, Ravi Inder Singh, S.K. Mohapatra

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

The design and operation of boilers using rice waste present a number of challenges. The overall capacity and efficiency of the boiler are strongly dependent on the fuel, and the supplier has to be able to guarantee the capacity and efficiency within the whole range of the fuel mixture being burned. It is well known that the exit gas composition is strongly dependent on the fuel. Bed temperature, fuel density and particle size significantly affect the hydrodynamic properties of a fluidized bed combustor. The effect of bed temperature, fuel density, particle size on exit gas composition and other hydrodynamic parameters …

Bench-Scale Investigation Of Limestone Size Evolution In A Fluidized Bed Combustor, Xuan Yao, Hairui Yang, Pierre Gauville, Hairui Yang, John H. Chiu, Shin G. Kang

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

The influence of temperature, heating rate and chemical reaction on fragmentation

and attrition of limestone in a fluidized bed (FB) was investigated. The intensity of

fragmentation and attrition was measured in the same apparatus but at different

fluidizing velocities and fluidizing media. It was found that the heating rate has a

positive effect on fragmentation for the tested limestones. The effect of bed

temperature on limestone fragmentation was inconclusive. The influence of

chemical reaction on the fragmentation seems to be complicated; CO2 release due to

calcination would prompt fragmentation while the sulfation would increase the gas

diffusion resistance and depresses …

The Variation Of The Bubble Phase Properties Of A Fcc Fluidized Bed At High Temperature, Rossella Girimonte, Brunello Formisani

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

Some important characteristics of the bubbling regime, relevant to a cut of FCC catalyst with an average size of 110 mm were investigated at 100, 400 and 700 °C. This was achieved by imploying data of bed collapse tests as well as images of the bubble eruption at the free surface of the bed by varying fluidization velocities and bed aspect ratios. The results show that a smoother regime of fluidization is observed at superambient temperature.

Effect Of Gas Bypassing In Deep Beds On Cyclone Dipleg Operation, Allan Issangya, Reddy Karri Dr, Ted Knowlton, Ray Cocco

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

Cyclone diplegs play a major role in the functioning of fluidized beds. Previous studies have shown that at certain operating conditions there can be severe gas bypassing (also referred to as jet streaming) of gas in deep beds of Geldart Group A materials which leaves significant portions of the fluid bed defluidized. If cyclone diplegs are immersed in these defluidized regions, solids discharge from the dipleg may be hindered, which can lead to the flooding of the dipleg and the cyclone. This could result in high solids losses from the fluidized bed. Tests were conducted to demonstrate that cyclone diplegs …

Fast Pyrolysis Process Intensification: Study Of The Gas Phase Residence Time Distribution And Backmixing In A Downer Reactor, Martin Huard, Franco Berruti, Cedric Briens

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

A downer reactor was developed at ICFAR to maximize the liquid yield of pyrolysis in the conversion of biomass and heavy oil feedstock. An experimental study using hot wire anemometers was performed to measure the residence time distribution of the gas phase in the reactor and around the gas-solids separator. Some gas backmixing was observed around the gas-solids separator, which decreased with increasing distance between the separator and the gas outlet.

Hydrodynamics Of Conical Spouted Beds With High Density Particles, Salih Sari, Aylin Polat, Dokugan Zaglamaris, Gorkem Kulah, Murat Koksal

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

An extensive experimental investigation of conical spouted beds with high density particles were carried out by measuring bed pressure drop, particle velocity and solids hold-up in a 15 cm ID conical spouted bed at three different cone angles (30°, 45°, 60°) with Yttria-stabilized zirconia (YSZ) particles (ρp = 6050 kg/m3). The results show that the minimum external spouting velocity increases with cone angle, particle diameter and static bed height. The bed is characterized by two regions: upward moving particles with high slip in the spout and slowly downward moving particles at loosely packed conditions in the annulus.

Experimental Study On The Effects Of Gas Permeation Through Flat Membranes On The Hydrodynamics In Fluidized Beds, J.A.M. Kuipers, J.F. De Jong, M. Van Sint Annaland

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

In this work, the effects of gas permeation through flat membranes on the hydrodynamics in a pseudo-2D membrane-assisted gas-solid fluidized bed have been investigated experimentally. A combination of the non-invasive Particle Image Velocimetry (PIV) and Digital Image Analysis (DIA) was employed to simultaneously investigate emulsion phase and bubble phase properties in great detail. Counter-intuitively, addition of secondary gas via the membranes, that constituted the confining walls of a gas-solid suspension at conditions close to incipient fluidization, did not result in a larger, but in a smaller bubble diameter, while gas extraction on the other hand, resulted in a larger equivalent …

Fluidization Behavior In A Gas- Solid Fluidized Bed With Thermally Induced Inter-Particle Forces, Jaber Shabanian, Farzam Fotovat, Jamal Chaouki, Jonathan Bouffard

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

In this work, a new approach for increasing and controlling inter-particle forces (IPFs) was applied. This method used a spherical inert particle coated with a polymer material having a low glass transition temperature. Since IPFs depend on the temperature of the coated particles, they can be easily controlled by the temperature of the inlet air. For this reason, the temperature of the system was varied uniformly near the glass transition temperature of the polymer, between 20 – 40oC, to investigate the effect of IPFs on fluidization behavior at low and high gas velocities

Correlation Of The Minimum Spouting Velocity For The Design Of Open-Sided Draft Tube Conical Spouted Beds For The Treatment Of Fine Materials, M. Olazar, Haritz Altzibar, Gartzen Lopez, I. Estiati, Javier Bilbao

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

The hydrodynamics of conical spouted beds provided with open-sided draft tubes have been studied for the treatment of fine particles. A correlation has been proposed for the calculation of the minimum spouting velocity as a function of dimensionless moduli that take into account the geometric factors of the contactor and the draft tube, particle characteristics and operating conditions.

Experiments And Modelling Of Micro-Jet Assisted Fluidization Of Nanopowder, Ruud Van Ommen, David M. King, Alan Weimer, Robert Pfeffer, Berend Van Wachem, Samantha Johnson, Niels Looije

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

The fluidization of nanoparticle agglomerates can be largely improved by using downward pointing micronozzles, creating a high-velocity jet, as experimentally shown. By discrete particle simulations – treating the agglomerates as single particles – we show that the microjet strongly reduces the amount of gas in voids.

Erosion In Second Stage Cyclones: Effects Of Cyclone Length And Outlet Gas Velocity, S. B. Reddy Karri, Ray Cocco, Ted Knowlton

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

Severe erosion in the lower cone and in the upper dipleg of second stage cyclones have been observed in commercial cyclones. The main objective of this study is to shed light on the mechanism by which this erosion takes place, and how different design and operating parameters affect the erosion. Experimental data on how parameters such as the cyclone length-to diameter ratio (L/D), inlet solids loading and gas outlet velocity affect second stage cyclone erosion are presented. The outlet gas velocity was varied by changing the size of the vortex tube diameter. The effect of a vortex stabilizer on cyclone …

Design Criteria Of Uniflow Cyclones For The Separation Of Solid Particles From Gases, Ulrich Muschelknautz, Paul Pattis, Michael Reinalter, Michael Kraxner

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

The main advantages of uniflow cyclones compared to standard reverse flow cyclones are their compact design and their capability of being easily integrated into pipelines. Experiments show that a 0.2m-diameter horizontal uniflow cyclone re-moves 88.6% of 2 g/m3 of fine mineral powder (d10=3m, d50=20m) from 1000 m3/h air at a pressure loss of 2510 Pa (0.364 psi).

Characteristics Of The Solid Volume Fraction Fluctuations In A Cfb, Sirpa Kallio, Juho Peltola, Veikko Taivassalo

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

In the paper, the fluctuation characteristics of the solids volume fraction in a CFB are evaluated from measurements and Eulerian-Eulerian CFD simulations. In both cases, similarly large fluctuations are observed in the intermediate voidage range whereas dense and dilute suspension regions are more uniform, as expected. The frequency distributions of solids volume fraction are classified to represent three different suspension density regimes: dilute, dense and intermediate “bimodal” regimes.

Gas-Solids Hydrodynamics In A Cfb With 6 Cyclones And A Pang Leg, Lemigh Cheng, Xinglong Zhou, Chao Wang, Qinhui Wang, Zhongyang Luo, Kefa Cen, Li Nie, Chaogang Wu, Qi Zhou

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

Solids volume fraction and particle velocity profiles were measured with a fiber optical probe in a cold circulating fluidized bed test rig with 6 parallel cyclones and a pant leg. Results in the pant leg zone, main bed zone and exit zone of the furnace are reported. The work also includes the influences of superficial gas velocity, secondary air rate and static bed height on the gas-solids hydrodynamics.

Fluidized Bed Gasification Of Mixed Plastic Wastes: A Material And A Substance Flow Analysis, Maria Laura Mastellone, Umberto Arena

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

Gasification as a reliable and convenient waste-to-energy process for the economic analysis of mixed-plastic waste (MPW) was investigated. To this end a pilot scale bubbling fluidized bed air gasifier was fired with two commercially available MPWs to obtain syngas composition and characterization of the bed material, cyclone collected fines and purge material from the scrubber. These results were then processed by means of Material and Substance Flow Analyses to evaluate the main process performance parameters for the two MPWs tested.

3d Cfd Simulation Of Combustion In A 150 Mwe Circulating Fluidized Bed Boiler, Nan Zhang, Bona Lu, Wei Wang, Jinghai Li

10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10

Eulerian granular multiphase model with meso-scale modeling of drag coefficient and mass transfer coefficient, based on the energy minimization multi-scale (EMMS) model, was presented to simulate a 150 MWe CFB boiler. The three-dimensional (3D), full-loop, time-dependent simulation results were presented in terms of the profiles of pressure, solids volume fraction and solids vertical velocity, the distributions of carbon and oxygen, as well as the temperature. The EMMS-based sub-grid modeling allows using coarse grid with proven accuracy, and hence it is suitable for simulation of such large-scale industrial reactors.