Entrainment flow types

To provide chemical industries with clean syngas even when using low-rank fuels such as salt-rich lignite or biomass entrained flow-type gasifiers were developed, offering many advantages in synthesis gas generation and downstream synthesis ... 

There are essentially three types of coal gasifiers moving-bed or countercurrent reactors fluidized-bed or back-mixed reactors and entrained-flow or plug-flow reactors. The three types are shown schematically in Eigure 2. 

Nq is strongly dependent on the flow regime, Reynolds Number, NRe, and installation geometry of the impeller. The flow from an impeller is only that produced by the impeller and does not include the entrained flow, which can be a major part of the total motion flow from the impeller. The entrained flow refers to fluid set in motion by the turbulence of the impeller output stream [27]. To compare different impellers, it is important to define the type of flows being considered. 

The company Noell in Germany, currently owned by Future Energy GmbH, has developed a down-fired entrained flow reactor (EFR). Instead of burners at the side of the reactor, this gasifier only consists of a single burner in the top part, which results in a simpler and lower cost reactor. Also, the control of this single burner is easier than the former types mentioned with a resulting lower capital and operational cost related. 

Other relevant gasifier types are bubbling fluid beds being tested by Enerkem and the high-pressure high-temperature slurry-fed entrained flow Texaco gasifier. 

There are three main types of gasification technology entrained flow, fluidized bed, and moving bed. All of these can... 

FIG. 24-4 Gasifier types and temperature profiles a) fixed bed (dry ash) h) fluidized bed (c) entrained flow. This figure teas published in N. Holt and S. Alpert, Integrated Gasification Combined-Cycle Po-werG vol. 7, pp. 897-905, in Encyclopedia of Physical Science and Technology 3d ed. Copyright Elsevier, 2002.)... 

This study shows that limited oxidation at 373 K or weathering (ambient) of coal feedstock reduces the thermoplastic properties of a coal This is manifest as a transformation in char type, from cenospheres to inertoids, at high rates of heating (10 -10 K s" ) in an Entrained Flow Reactor at 1273 K. The specific types of char are related to the chemical structure of the coal and an inverse relationship exists between the occurrence of cenospheric chars and the atomic 0/C ratio of the oxidised or weathered coal from which they are derived... 

Entrained flow reactor (riser) This is a fluidized-bed reactor in which the solid is entrained by the fluid phase and is recycled throughout the operation (Figure 3.9). Some applications of this reactor type are the modem FCC process and the calcination of alumina hydrate. 

Reactor Vessel used for gasification, liquefaction, and pyrolysis, with the three main types the moving packed bed, the entrained flow, and the fluidized bed reactor. 

The reactor type strongly influences the temperature distribution and, in this way, the gas and residue products. The reaction temperature typically varies from about 800 to 1500°C, and up to a maximum of about 1900°C in entrained flow oxygen reactors. Each type of gasifier... 

In order to achieve rapid heating of the biomass, it should be finely ground. The particle size of the biomass is dependent on the reactor type used. In particular, it was reported [17] that ablative reactors can pyrolyze large-size feedstocks, whereas the fluidized beds require smaller (below 3 mm) particles [16]. The difference is due to lower heat transfer through conduction in the fluidized beds, which is even lower in the entrained flow reactor, being in the range of 4% [17],... 

Gasification processes can be separated into three major types (1) moving-bed (counter-current flow) reactors (2) fluidized-bed (back-mixed) reactors and (3) entrained-flow (not back-mixed) reactors. Figure 19.11 shows the types of gasification reactors together with temperature profiles and locations of feed and product streams. Table 19.12 summarizes the important characteristics of each type of gasifier, and Table 19.13 presents the performance characteristics of selected gasifiers. 

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