Entrained Flow Technologies

Hitachi. This coal gasification technology is based on an oxygen-blown entrained flow gasifier, where the majority of experience has been gained in a 150 ton coal/day unit. The gasifier is a water-cooled tube that is lined by a high-temperature-resistant castable. Pulverized coal is pneumatically 

SCGP The Shell Coal Gasification Process (SCGP) can operate on a wide variety of feedstocks. It consists of three principal stages  

Gasification (Partial Oxidation), in which the feedstock is converted to syngas in the presence of oxygen and a moderating agent (steam) in a refractory-lined gasification reactor 

Syngas Effluent Cooler (SEC), in which high-pressure steam is generated from the hot syngas leaving the reactor 

Carbon Removal, in which residual carbon and ash are removed from the syngas in a two-stage water scrubbing unit 

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As discussed previously, the Destec Plaquemine project is demonstrating the Destec coal gasification process on subbituminous coals. The use of this two-stage entrained flow technology for bituminous coals poses several technical concerns. Specifically, bituminous coal increases the potential for liquid hydrocarbon formation in the top stage and increases the recycle of char from the top stage to the bottom stage. 

High Temperature Winkler, and Shell. These technologies and their demonstration projects are reviewed in the guide. The East German GSP system could also be considered a demonstration technology. However, it is not reviewed because of the low interest in this system in North America. In addition, the GSP process is similar to entrained-flow technologies such as Shell and Texaco. 

The Shell and PRENFLO coal gasification processes are quite similar they both use pressurized, dry feed, entrained-flow technologies with water wall-cooled gasifier vessels. 

Physical properties Friability Depends on the fibrous nature of the biomass (the more fibrous nature the lower friability) Low Mability influences pretreatment and feeding systems (particularly for entrained-flow technology)... 

The principal advance ia technology for SASOL I relative to the German Fischer-Tropsch plants was the development of a fluidized-bed reactor/regenerator system designed by M. W. Kellogg for the synthesis reaction. The reactor consists of an entrained-flow reactor ia series with a fluidized-bed regenerator (Fig. 14). Each fluidized-bed reactor processes 80,000 m /h of feed at a temperature of 320 to 330°C and 2.2 MPa (22 atm), and produces approximately 300 m (2000 barrels) per day of Hquid hydrocarbon product with a catalyst circulation rate of over 6000 t/h (49). 

PRessurized ENtrained FLOw) gasification technology. Initially developed by Krupp Uhde. Krupp and Shell. They split in 1981 and both developed their own coal gasification process. 

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.)... 

In a suspended bed or entrained flow reactor technology, the coal is crushed, dried, and then pulverized to fine powder in a crusher and mill. As Table 9.1 shows, the coal particles used in entrained flow reactors are very small. The pulverized coal is transported with air to the furnace (primary air), and secondary air is heated and fed into the combustor to ensure complete combustion. The residence time of the coal in the furnace is typically around 1-2 s, which usually suffices for complete combustion. However, not all coal burns completely, and fly ash will be generated (see Table 9.1). 

Figure 2.3.5 Gasification technologies/routes (Atm. = atmospheric pressure Pres. = pressurized FB = fluidized bed [both bubbling and circulating] M/F Bed = moving or fixed bed EF = entrained flow).

Matsen, J. M. Mechanisms of choking and entrainment, Powder Technology 32,21-33 (1982). Militzer, J. Numerical prediction of the fully developed two-phase (air-solids) flow in a pipe, in Circulating Fluidized Bed Technology (P. Basu, ed.), pp. 173-184. Pergamon Press, 1986. 

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