Study On The Characteristics Of Slag And Fly Ash Which Generated From Entrained-bed Gasifiers

The properties of the entrained flow gasification slag and fly ash are analyzed basing on the study of the pressurized entrained flow coal gasification pilot plant which produce slag and fly ash (Shell gasifier, the waste heat boiler of GE gasifier).The thesis gives a depth analysis on the characteristics of slag that generated from the coal gasification pilot plant, such as the content of combustible, the apparent shape, size distribution, composition of the mineral and the migration of elements in the slag, with the impact of temperature on these factors. In order to reveal the adhesion behavior of fly ash, the experimental setup about adhesion of fly ash is trying to be designed.By the determination of the combustibles content and the particle size distribution of the slag, it is found that there is great difference between the coarse slag and fine slag, which result from the different path. The coal particles come through the gasifier. The combustibles content has close relationship with the Residue in the fuel and operating conditions of the ratio of oxygen. And the coal and the kind of the coal. The higher the oxygen-coal ratio, the lower the fuel concentration, and more large the particle size. The content of some metals and S element in the coal will also greatly influent the combustibles content and the particle size of slag.The apparent form of the coal and slag samples, the mineral composition of slag, major elements and trace elements are analyzed by SEM, XRD, XRF, ICP-AES and other techniques. It is found that temperature has greater impact on these factors:the higher the temperature, the more thick the surface of the slag, and mineral crystal form will change. The temperature influence greatly on the element migration, especially on the migration of trace elements, trace elements tend to be enriched in the low-temperature slag. To imitate the behaviour of trace elements by Fact-Sage in the gasification. And compare the resualts with the experiments. This will provide the support for in-depth knowledge of trace element.Design experimental setup to determine the adhesion characteristics of fly ash. The temperature has great effect on the adhesion characteristic of fly ash, the particle adhesion will greatly increases at certain temperature.