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Fluid cracking fluidization

Fluidized-bed catalytic cracking units (FCCUs) are the most common catalytic cracking units. In the fluidized-bed process, oil and oil vapor preheated to 500 to SOOT is contacted with hot catalyst at about 1,300°F either in the reactor itself or in the feed line (called the riser) to the reactor. The catalyst is in a fine, granular form which, when mixed with the vapor, has many of the properties of a fluid. The fluidized catalyst and the reacted hydrocarbon vapor separate mechanically in the reactor and any oil remaining on the catalyst is removed by steam stripping. [Pg.88]

Both devices described above were developed in order to test the friability of fluid-cracking catalysts. Nowadays the application of these or similar tests is a common procedure in the development of fluidized bed catalysts. Contractor et al. (1989), for example, used a submerged-jet test to compare the attrition resistance of newly developed VPO catalysts. In fact, such tests can be applied to any type of fluidized bed processes. Sometimes they have to be slightly modified to adapt them to the process under consideration. The drilled plate may, for example, be substituted by... [Pg.451]

Prior to 1938, gasoline was obtained from thermal-cracking plants then the Houdry fixed-bed catalytic cracking process led to the development of a fluidized-bed process by Standard Oil for the catalytic production of motor fuels (4-8). Acid-treated clays of the montmorilIonite type were the first fluid-cracking catalysts widely employed by the industry. However, the ever greater demand for aviation fuels during the 1939-1945 period prompted the search for more active and selective catalysts. Research on novel catalyst... [Pg.1]

Commercial fluid cracking catalysts are predominantly particles with diameters ranging from 20 to 100 microns and densities of the order of 1.0 to 1.6 g./cc. (based on geometric volume of particles including pores). Gas velocities of 1 to 2.5 ft./second are ordinarily used in the reaction vessels of fluid cracking units. Within this range, the bulk density of the dense-phase fluidized bed is typically 40 to 60% of the bulk density of the packed static bed. [Pg.322]

The weight of catalyst in a vessel is determined by measuring the pressure differential between taps installed at the top and bottom. Density of the fluidized catalyst is determined in a similar manner from the differential pressure between taps located a measured distance apart in the dense phase. Location of the catalyst level can be determined from the combination of the density and the total weight of catalyst, or by the use of a series of pressure taps placed at intervals along the height of the vessel. A hot-wire probe has been used to locate the level in laboratory fluidized beds (250), but this technique has not been adopted for fluid cracking units. The method depends upon the fact that heat-transfer rate from the heated wire is much higher when immersed in the dense phase of fluidized solids than when in the dilute phase. [Pg.348]

Figure 84 Greldhart classification of particles for fluidization by air at ambient temperature. Region A corresponds to the properties of well-behaved fluid cracking catalysts. [After D. Kunii and O. Levenspiel, Fluidization Engineering, with permission of Butterworth-Heinemann, Boston, MA, (1991).]... Figure 84 Greldhart classification of particles for fluidization by air at ambient temperature. Region A corresponds to the properties of well-behaved fluid cracking catalysts. [After D. Kunii and O. Levenspiel, Fluidization Engineering, with permission of Butterworth-Heinemann, Boston, MA, (1991).]...
The decomposition of ozone was studied in a fluidized bed 0.1 m in diameter using different samples of fluid cracking catalyst [16,19]. Some data for catalyst with a broad size distribution and a mean particle size of 60 txm are given in Table 9.1. Use Model II to calculate the values of K. [Pg.381]

Boerefijn R, Zhang SH, Ghadiri M. Analysis of ISO fluidized bed test for attrition of fluid cracking catalyst particles. In Fan LS, Knowlton TM, eds. Fluidization IX. New York Engineering Foundation, 1998, pp 325-332. [Pg.242]

These empirical correlations were mostly determined for fluidized beds of fine sand or fluid cracking catalyst. It is advised to use these relations only for applications of these materials. For applications of other powders it is better to measure mass transfer rates in small scale fluidized b s, and use empirical equations for predicting the scale-up effects. When one wants to use a new catalyst in really large reactors, e.g., with a diameter and a height of several meters, one should preferably do some pilot tests with the catalyst in a "cold flow model reactor of at least 1 m diameter. Measurements of mass transfer rates under realistic flow conditions may be sufficient. [Pg.96]

In fluid catalytic cracking, a partially vaporized gas oil is contacted with zeoflte catalyst (see Fluidization). Contact time varies from 5 s—2 min pressure usually is in the range of 250—400 kPa (2.5—4 atm), depending on the design of the unit reaction temperatures are 720—850 K (see BuTYLENEs). [Pg.126]

Figure 2.3.2 (Kraemer and deLasa 1988) shows this reactor. DeLasa suggested for Riser Simulator a Fluidized Recycle reactor that is essentially an upside down Berty reactor. Kraemer and DeLasa (1988) also described a method to simulate the riser of a fluid catalyst cracking unit in this reactor. Figure 2.3.2 (Kraemer and deLasa 1988) shows this reactor. DeLasa suggested for Riser Simulator a Fluidized Recycle reactor that is essentially an upside down Berty reactor. Kraemer and DeLasa (1988) also described a method to simulate the riser of a fluid catalyst cracking unit in this reactor.
Fluid bed reactors became important to the petroleum industry with the development of fluid catalytic cracking (FCC) early in the Second World War. Today FCC is still widely used. The following section surveys the various fluid bed processes and examines the benefits of fluidization. The basic theories of fluidization phenomena are also reviewed. [Pg.26]

Fluid bed processes have been subject to many problems and uncertainties in development and scale up from bench-scale reactors. The fluidization behavior of each process seems different and very often does not meet expectations based on experience with earlier plants. With hindsight fluid cat cracking seems to be an ideal system from the point of view of easy operation and straightforward scale up. [Pg.28]

In the fluid coking process, part of the coke produced is used to provide the process heat. Cracking reactions occur inside the heater and the fluidized-bed reactor. The fluid coke is partially formed in the heater. Hot coke slurry from the heater is recycled to the fluid reactor to provide the heat required for the cracking reactions. Fluid coke is formed by spraying the hot feed on the already-formed coke particles. Reactor temperature is about 520°C, and the conversion into coke is immediate, with... [Pg.58]

Fluid catalytic cracking is one of the most important conversion processes in a petroleum refinery. The process incorporates most phases of chemical engineering fundamentals, such as fluidization, heat/mass transfer, and distillation. The heart of the process is the reactor-regenerator, where most of the innovations have occurred since 1942. [Pg.39]

Squires, A. M., The Story of Fluid Catalytic Cracking The First Circulating Fluid Bed, Proc. First Intern. Conf. Circulating Fluidized Bed, p. 1-19 (1985)... [Pg.580]


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See also in sourсe #XX -- [ Pg.321 , Pg.322 ]




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