Slurry bubble column

Reactor type Slurry bubble colunrn Slurry bubble column Slurry airlift reactor... 

Reactor t3q>e slurry bubble column circulating slurry reactor... 

In the above three processes, the catalysts are all composed of Cu-based methanol synthesis catalyst and methanol dehydration catalyst of AI2O3. The reactors used by JFE and APCI are slurry bubble column, while a circulating slurry bed reactor was used in the pilot plant in Chongqing. It can be foxmd from Table 1 that conversion of CO obtained in the circulating slurry bed reactor developed by Tsinghua University is obvious higher and the operation conditions are milder than the others. 

Two basically different reactor technologies are currently in operation low temperature and high temperature. The former operates at -220 °C and 25-45 bar, employing either a multitubular, fixed bed (i.e. trickle bed) reactor or a slurry bubble column reactor with the catalyst suspended in the liquid hydrocarbon wax product. 

The term three-phase fluidization, in this chapter, is taken as a system consisting of a gas, liquid, and solid phase, wherein the solid phase is in a non-stationary state, and includes three-phase slurry bubble columns, three-phase fluidized beds, and three-phase flotation columns, but excludes three-phase fixed bed systems. The individual phases in three-phase fluidization systems can be reactants, products, catalysts, or inert. For example, in the hydrotreating of light gas oils, the solid phase is catalyst, and the liquid and gas phases are either reactants or products in the bleaching of paper pulp, the solid phase is both reactant and product, and the gas phase is a reactant while the liquid phase is inert in anaerobic fermentation, the gas phase results from the biological activity, the liquid phase is product, and the solid is either a biological carrier or the microorganism itself. 

The development of three-phase reactor technologies in the 1970 s saw renewed interest in the synthetic fuel area due to the energy crisis of 1973. Several processes were developed for direct coal liquefaction using both slurry bubble column reactors (Exxon Donor Solvent process and Solvent Refined Coal process) and three-phase fluidized bed reactors (H-Coal process). These processes were again shelved in the early 1980 s due to the low price of petroleum crudes. 

The 1980 s and the early 1990 s have seen the blossoming development of the biotechnology field. Three-phase fluidized bed bioreactors have become an essential element in the commercialization of processes to yield products and treat wastewater via biological mechanisms. Fluidized bed bioreactors have been applied in the areas of wastewater treatment, discussed previously, fermentation, and cell culture. The large scale application of three-phase fluidized bed or slurry bubble column fermen-tors are represented by ethanol production in a 10,000 liter fermentor (Samejima et al., 1984), penicillin production in a 200 liter fermentor (Endo et al., 1986), and the production of monoclonal antibodies in a 1,000 liter slurry bubble column bioreactor (Birch et al., 1985). Fan (1989) provides a complete review of biological applications of three-phase fluidized beds up to 1989. Part II of this chapter covers the recent developments in three-phase fluidized bed bioreactor technology. 

Saxena, S. C., Rosen, M., Smith, D. N., and Ruether, J. A., Mathematical Modeling of Fischer-Tropsch Slurry Bubble Column Reactors, Chem. Eng. Comm., 40 97 (1986)... 

Toseland, B. A., Brown, D. M., Zou, B. S., and Dudukovi..M., Flow Patterns in a Slurry-Bubble-Column Reactor Conditions, Trans. Inst. Chem. Engrs., 73 297 (1995)... 

FTS activity (215-232°C, 19-28 bar, H2/CO = 1.98-2.28) in a two-stage slurry bubble column using a Co/A1203 catalyst, (b) Correlation between amounts of residual carbon after 02 treatment and H2 chemisorption capacity. (Drawn from data provided in Gruver et al.34)... 

FIGURE 4.7 Methane TPH profile of a wax-extracted 20 wt% Co/A1203FTS catalyst taken from a 100 bbl/day slurry bubble column operated at realistic FTS conditions.73... 

Gruver, V., Young, R., Engman, J., and Robota, H. J. 2005. The role of accumulated carbon in deactivating cobalt catalysts during FT synthesis in a slurry-bubble-column reactor. Prepr. Pap.-Am. Chem. Soc. Div. Pet. Chem. 50 164—66. 

A continuous cross-flow filtration process has been utilized to investigate the effectiveness in the separation of nano sized (3-5 nm) iron-based catalyst particles from simulated Fischer-Tropsch (FT) catalyst/wax slurry in a pilot-scale slurry bubble column reactor (SBCR). A prototype stainless steel cross-flow filtration module (nominal pore opening of 0.1 pm) was used. A series of cross-flow filtration experiments were initiated to study the effect of mono-olefins and aliphatic alcohol on the filtration flux and membrane performance. 1-hexadecene and 1-dodecanol were doped into activated iron catalyst slurry (with Polywax 500 and 655 as simulated FT wax) to evaluate the effect of their presence on filtration performance. The 1-hexadecene concentrations were varied from 5 to 25 wt% and 1-dodecanol concentrations were varied from 6 to 17 wt% to simulate a range of FT reactor slurries reported in literature. The addition of 1-dodecanol was found to decrease the permeation rate, while the addition of 1-hexadecene was found to have an insignificant or no effect on the permeation rate. 

Oukaci, R., Singleton, A.H., and Goodwin Jr., J.G. 1999. Comparison of patented Co F-T catalysts using fixed-bed and slurry bubble column reactors. Appl. Catal. A 186 129 14. 

Fe-LTFT Sasol Slurry Bed Precipitated Fe Slurry bubble column 1993 Sasol 1, Sasolburg, South Africa... 

Co-LTFT Sasol Slurry Bed Supported Co Slurry bubble column 2007 Oryx, Ras Laffan, Qatar... 

AGC-21 A process for converting natural gas to liquid fuels in three stages generation of syngas in a fluidized bed, Fischer-Tropsch synthesis in a slurry bubble column reactor, and hydrocracking. Piloted in 1997 and proposed for installation in Qatar. 

GTSC [Gas to syncrude] A process for converting natural gas to a synthetic crude oil which may be mixed with natural crude oil and used in conventional oil refineries. Based on F-T technology, but using a proprietary slurry bubble column reactor with a promoted cobalt catalyst. Developed by Syncrude Technology, Pittsburgh, PA, in the 1990s. 

Slurry Bubble Column Reactors (SBCR) This reactor is tubular (Figure 3.12). The liquid is agitated by means of dispersed gas bubbles. Gas bubbles provide the momentum to suspend the catalyst particles. The gas phase flows upward through the reactor at a constant rate. This reactor could be of continuous type or of semibatch type. This type is used only in catalysis. 

There are two types of slurry reactors slurry bubble column reactor (SBCR, Figure 3.25) and agitated slurry reactor (ASR, Figure 3.26). These reactors differ in that the solid... 

Figure 3.25 Slurry bubble column reactor (SBCR)...

In the common case, in slurry bubble column reactors, the catalyst phase remains in the reactor while the liquid phase could remain in the reactor with a continuous flow of gas (semibatch operation). Both gas and liquid could be in plug flow or could be well mixed. 

The most important applications of slurry bubble column reactors ... 

In a typical slurry bubble column operation, the liquid velocity is one order of magnitude lower than the one of gas, and in general, is very low. This mode of operation can be approximated by a semibatch operation. The semibatch operation is frequently used and is the case where the liquid and the catalyst comprise a stationary phase (sluny) in the reactor. In this case, the material balance, eq. (3.122) is used along with the overall rate based on the bulk gas-phase concentration (see Section 3.4.6). In the following, the semibatch operation is presented. 

Finally, the relationship between the several rate expressions for slurry bubble column reactors is (see Section 3.1.1 for derivation)... 

The hydrodynamics of bubble columns and slurry bubble column reactors depend strongly on the flow regime (Figure 3.27). There are three flow patterns that prevail in these reactors (Wallis, 1969 Shall et al., 1982) ... 

For maximum utilization of the solid phase in a bubble column, it is essential that all particles be suspended in the reactor (Ramachandran and Chaudhari, 1984). This means that the gas velocity should be sufficiently high to enable suspension of all solids in the liquid. In slurry bubble column reactors, two suspension states exist ... 

It has been reported that for diameters less than 7.62 cm, the gas holdup depends on the column diameter, whereas it is independent of it for diameters greater than 10.2 cm (Hughmark, 1967 Saxena, 1991). The same has been found in studies of the Fisher-Tropsch synthesis in slurry bubble columns, where it has been reported that the effect of the column diameter is negligible when foam is not present in the system (Fox and Degen, 1990). 

---