Internally circulating fluidized bed

Y.W. Jang, Steam Gasification of Bituminous Coal in a Bench-Scale Internally Circulating Fluidized Bed, MS Thesis, Kunsan National University, Korea, 2002. 

This concept was first called a recirculating fluidized bed by Yang and Kearins (1974). Several other names have also been used to describe the same concept the fluid-lift solids recirculator (Buchanan and Wilson, 1965), the spouted fluid bed with a draft tube (Y ang and Keaims, 1983 Hadzismajlovic et al., 1992), the internally circulating fluidized bed (Milne et al., 1992 Lee and Kim, 1992) or simply a circulating fluidized... 

The fast internally circulating fluidized-bed (FICFB) gasifier (developed by Technical University (TU) Vienna, Austria)... 

Marschall KJ, Mleczko L. CFD modeling of an internally circulating fluidized-bed reactor. Chem Eng Sci 1999 54 2085-2093. 

Subbarao, D. and Gambhir, S., Gas to particle mass transfer in risers, in "Proceedings of 7th International Circulating Fluidized Beds Conference", pp. 97-104, Canadian Society for Chemical Engineering, Niagara Falls. 

Bruce, J., Milne, Franco Berruti, and Leo A. Behie. The Hydrodynamics of the Internally Circulating Fluidized Bed at High Temperature, in Circulating Fluidized Bed Technology IV (Amos A. Avidan, ed.), pp. 29-34. Somerset, Pennsylvania (1993). 

Milne et al. [42] used an internally circulating fluidized bed to study pyrolysis of low-density PE (LDPE) at temperatures ranging from 780 to 860° C and residence times of 400-600 ms. They achieved gas yields in excess of 90 wt% with total aUcene yields as high as 75 wt%, demonstrating a waste treatment potential for processes snch as flash pyrolysis, distinguished from classical pyrolysis by its high heating rates and low retention times, where these conditions can be maintained. 

Zschctzsche, A. Hofbauer. Schmidt, A. (1994). "Biomass Gasification in an Internally Circulating Fluidized Bed". Proc.of the S" European Conference on Biomass for Agriculture and Industry, Vol, 3, pp. 1771-1777... 

Schematic diagram of a pilot plant for the thermal conversion of plastic wastes with an internally circulating fluidized bed reactor.30...

The third example, fast fluidization, can also be achieved in a concentric circulating fluidized bed. One option is to have solids flow up in the center and down in the annular shell. This has been called an internally circulating fluidized bed. Alternatively, one can have solids flow up in the annular shell and... 

Milne BJ, Berruti F, Behie LA. Solids circulation in an internally circulating fluidized bed (ICFB) reactor. In Fluidization VII (OE Potter, DJ Nicklin, eds.). Engineering Foundation, New York, 1992a, pp 235-242. 

Milne BJ, Berruti F, Behie LA, de Bruijn, TJW. The hydrodynamics of the internally circulating fluidized bed at high temperature. In Avidan AA (ed.), Circulating Fluidized Bed Technology IV. AIChE, New York, 1994, pp 28-31. 

Wang ZL, Yao JZ, Liu SJ, Li HZ, Kwauk M. Studies on the voidage distribution in an internally circulating fluidized bed (in Chinese). In Proceedings 6th National Conf. on Fluidization, Wuhan, China, Oetober 1993, pp 150-154. 

In recent years, the term circulating fluidized bed has also been used for liquid-solid systems and gas-liquid-solid (three-phase) systems. These are treated in Chapters 26 and 27. However, the predominant interest in CFB systems continues to be for gas-solid (two-phase) systems, and we restrict this chapter to this case. Some mention is also made in the literature of internally circulating fluidized beds where the particles circulate around one or more loops within a main reactor space or vessel. This chapter deals principally with gas-solid systems where solids recirculate through an external solids flow system, usually involving one or more eyelones, a standpipe, and a valve or seal, either non-meehanieal (e.g., L-valve or loop seal see Chapter 21) or meehanical (e.g., slide valve). 

A circulating fluidized bed ean also be constructed in a concentric configuration as an internally circulating fluidized bed. The riser is usually located in the interior with the downcomer as an outer armulus (e.g., Fusey el al., 1986). Such geometries simplify construction, facilitate direct heat exchange between the riser and the downcomer, and simplify the design of high-pressure systems. 

Lee WJ, Kim SD. Hydrodynamics and CWM combustion characteristics in an internally circulating fluidized bed combustor. In Potter OE, Nicklin DJ, eds. Fluidization VII. New York Engineering Foundation, 1992, pp 479-486. 

The Internally Circulating Fluidized Bed. To improve further the design of a reactor suitable for operation in the ultrapyrolytic regime and on the basis of the above described experimental observations, a novel reactor has been recently proposed. This improved version, called Internally Circulating Fluidized Bed (ICFB), has been designed and two prototypes (a cold semi-cylindrical acrylic unit as well as a cylindrical hot pilot plant) have been constructed and extensively operated. 

Because the flow pattern inside gasification reactors is of prime importance to understand gasifier behavior, this section is dedicated to give an engineering-oriented and pragmatic overview how to approach the complex field of CFD utilization for coal gasification. On the example of internal circulating fluidized bed (INCI) concept development, explained in detail in Chapter 9, test calculations should be accomplished to understand the basic relationships of the system. 

Table 6.19 Modeling results for high-temperature Winkler (HTW) and internal circulating fluidized bed (ICFB) gasification.

Figure 7.10 Explanation of the gasifier symbols from Figure 7.9 (ICFB - internal circulating fluidized bed).

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