TABLE OF CONTENTS As discussed at the beginning of this chapter, the principal advantages of using entrained flow are the ability to handle practically any coal as feedstock, and to produce a clean, tar-free gas. Additionally, the ash is produced in the form of an inert slag or frit. This is achieved with the penalty of a high oxygen consumption, especially in the case of coal-water slurries or coals with a high moisture or ash content, as well as additional effort in coal preparation.
Nonetheless, even if entrained flow has been selected as the means of contacting the fuel and gasification agent, this still leaves a considerable variety of alternatives open in the design approach, as can be judged from Table 5.8, which outlines characteristics of some important entrained-flow processes.
| Process | Stages | Feed | Flow | Reactor wall | Syngas cooling | Oxidant |
|---|---|---|---|---|---|---|
| Koppers-Totzek | 1 | Dry | Up | Jacket | Syngas cooler | Oxygen |
| Shell SCGP | 1 | Dry | Up | Membrane | Gas quench and syngas cooler | Oxygen |
| Prenflo | 1 | Dry | Up | Membrane | Gas quench and syngas cooler | Oxygen |
| Siemens | 1 | Dry | Down | Membrane | Water quench and/or syngas cooler | Oxygen |
| GE Energy | 1 | Slurry | Down | Refractory | Water quench or syngas cooler | Oxygen |
| E-Gas | 2 | Slurry | Up | Refractory | Two-stage gasification | Oxygen |
| MHI | 2 | Dry | Up | Membrane | Two-stage gasification | Air |
| Eagle | 2 | Dry | Up | Membrane | Two-stage gasification | Oxygen |
The majority of the most successful coal gasification processes that have been developed after 1950 are entrained-flow, slagging gasifiers operating at pressures of 20 70 bar and...
