Coal-water-slurry feeding

The GE coal gasifier, shown in Figure 5, originally developed by Texaco, is a down-flow, entrained-flow, slagging design. It uses a coal-water slurry feed, which... 

It is also possible to inject up to 40wt% of the feed coal by dense-phase conveying or coal-water-slurry feeding at the gasifying agent injection level. Therefore, the coal must be grinded to <100 pm [206,213],... 

ECUST TPRI Entrained flow 2-step entrained flow Coal-water slurry Dry feeding o2 o2 2-6.5 1300-1400 1400-1500 98-99... 

The feed system is an important choice for entrained-flow gasifiers. GE and E-Gas use a coal-water slurry compared with the dry-feed systems of Shell and Future Energy, which require lock hoppering. 

Min-U-Gel . [Floridin] Attapulgiteclay absorbent, adsorbent, gellant, suspend-iiig agent, stabilizer, thickener for t ric. formulations, animal feeds, asphalt cutabacks, coal water slurries, paints. 

Recently the phase inversion-based coal-C02 slurry (PHICCOS) feeding system was presented as an alternative feeding method [23,24]. The main idea behind it is to prepare a coal-water-slurry that is compressed to 80 bar using conventional techniques. Downstream, the coal-water-slurry should be contacted with liquid CO2 at 30 °C. The principle of phase inversion postulates that a hydrophobic liquid, such as CO2, displaces water on the surface of the coal especially on the carbonaceous parts, also referred to as selective... 

The tuyere nozzles may have a second feed pipe for injection of pulverized coal, dusty tar/oil, coal-water-slurry, or gas liquor [2,206,210]. 

In the case of the E-Gas gasification, the first stages can also be displayed as distinct points, which are inside the slurry-feed entrained-flow domain for the standard system and inside the dry-feed domain for the enhanced system (entrained slagging transport reactor [E-STR]). The slurry point, which is located at the coal-H20 axis, represents the coal-water slurry that is introduced in the second stage. The overall mixing points, again, represent the outlet of the gasifier and can be found inside the fluid-bed domain. 

Since the completion of this project other processes utilizing carbon dioxide and water benefication have been developed (12). Specifically, in this work liquid carbon dioxide near the critical point is used to coalesce the coal and leave behind ash components. The coal feed is a water slurry in this project. The coal is cleaned by the characteristics of two Immiscible phases in sharp contrast to the miscible carbon dioxide water treatments described in this paper. 

In the tests made using slurry feeding, the concentration of coal in relation to steam and Stage 1 gas was not as high as visualized for the commercial process. Thus, development of a dry coal feeder in which the coal feed rate is independent of the amount of water fed into the reactor represented a major improvement over the slurry feeding system. 

Beside the highest possible cobalt and copper recoveries, the auto-thermal operation of those fluid bed roasters, were of prime importance in order to avoid the extra operating cost of auxiliary fuel consumption. In order to limit any fuel (coal) addition, the feed slurry was maintained at 75 wt% solids to minimize the energy loss to water vaporization. This resulted in a slurry that presented a significant challenge in the roaster feed system design due to its high viscosity and solid content. 

The various gasifiers dififer in method of feeding and in waste heat recovery [230], The GE (Texaco) gasifier feeds coal in a waste slurry (paste) which means that oxygen is used for evaporation of water. However, the slurry feed system allows a much higher pressure (up to 70-80 bar) than possible for gasifiers with dry feeding systems. 

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