Selection of a coal gasification method

This is a characteristic of lignite; it can be subjected to pressurized gasification using dry pulverized coal. The advantages include high gasification efficiency, low coal consumption, a low methane content in the syngas, and few by-products that are difficult to handle. However, drying the raw coal requires significant effort and energy, and the investment involved is also high. Coal pulverization pressurized gasification technology can also be used; its advantages are low investment and low oxygen consumption. However, the syngas contains a high level of methane, there are other by-products, and the amount of wastewater generated is large, making it difficult to treat.

Choosing a fluidized bed is the right approach; the challenge with dry powder feeding lies in drying the coal； The disadvantage of wet feed, namely slurry gasification, is that the concentration of the coal slurry cannot be increased. It is recommended to conduct a slurry-forming test on this coal, and then make a decision after comparing aspects such as investment and technology.

I learned from the teachers on the 2nd and 3rd floors*, and I think the analysis presented by those two gentlemen is quite reasonable! For dry coal powder fluidized bed pressurized gasification methods such as SHELL, the relatively higher carbon conversion rate compared to Texaco water-coal slurry gasification is achieved by raising the gasification temperature. Is this approach suitable for coal types with a low ash fusion point, as mentioned by the original poster? Should anything else be added to increase the ash fusion point of coal? :lol

From environmental and technical perspectives, powder coal gasification methods such as those used by Shell are the preferred choice. From an investment standpoint, both Lurgi and Endress boilers represent good options

Currently, the main gasification processes used in China are those developed by Shell and Texaco. As you mentioned, coal of a certain quality is suitable for Shell’s gasification process, but the investment required is very high; therefore, its use in China is not yet satisfactory. In my opinion, the Anode furnace process could be a good option, as it requires less investment, although it has a higher coal consumption

Regardless of the gasification technology used, do high moisture and high ash content result in higher specific oxygen consumption and specific coal consumption compared to other types of coal?

I disagree; Shell and Texaco seem to be viable options, but in reality they aren’t. Theoretically, these two methods can make use of all coal (Texaco needs coal to produce water-coal slurry), but the economic viability of using such coal is very poor. The Lurgi pressurized gasification process with liquid slag discharge can be employed, as this process offers significant advantages due to the low melting point of the ash.

What are the disadvantages or negative effects of using this type of coal in SHELL or GSP dry coal powder gasification? I do not think that SHELL and GSP dry coal powder gasification is suitable for all types of coal, because when it comes to suitability, one must consider technical feasibility, economic viability, and operational reliability. This post was last edited by Pioneering Spirit on 2008-1-7 15:54]

See how large it is; if it’s not very large, then the End furnace is a viable option

I have the following immature opinions; I welcome feedback and corrections from all teachers: 1. The water content is high, and if water-coal slurry gasification is used, it is not possible to increase the concentration of the slurry, which results in a higher specific oxygen consumption； In the case of dry coal powder gasification, significant energy is required for drying the coal powder before it enters the gasifier. 2. The ash content is high; if water-coal slurry gasification is used, the oxygen consumption increases ； If dry coal powder gasification is used, the specific oxygen consumption will also increase. 3. With a high moisture content and a high ash content, using any existing coal gasification technology poses problems in terms of cost and economic viability. 4. A more reasonable approach might be to modify the coal quality first, by reducing its moisture and ash content, regardless of whether water-coal slurry gasification or dry coal powder gasification is used. This post was last edited by sdz*a on 2008-1-12 11:40]

With a high internal water content, coal-water slurry is not an option. If pressure requirements are not a concern, Entho furnace and ash fusion polymerization are both good choices.

Don’t coals with a low ash fusion point tend to form slag deposits more easily?

The analysis data for the coal should be made available. This coal can be modified to use Texaco technology.

It is most suitable for dry gasification; with wet methods, the pulp concentration simply cannot be increased. If you don’t believe it, you can send it to the Northwest Research Institute for a pulp formation test – I heard their results are quite good! Hehe.

With high moisture and high ash content, if SHELL dry coal powder gasification is used, the effective components H2+CO in the raw gas won’t be high either, right?

If economic factors are not taken into account and we consider only technical aspects, companies such as GE, multi-nozzle coal water slurry systems, SHELL, GSP, and LURGI are all capable of gasifying this type of coal. GE’s predecessor, TEXACO, claimed to have a universal furnace when it first entered the Chinese market; after many years of \"testing\" in China, GE has accumulated extensive operational experience, and it no longer makes such claims； The current SHELLs and GSPs are trying to deceive the Chinese people by following in TEXACO’s footsteps from back then; after all, those who made wrong decisions will never admit their faults no matter what happens – one side is willing to act, and the other is willing to suffer!

In my opinion, this type of coal should not be processed using the water-coal slurry gasification method, as it has a high ash content, making the treatment of ash-water quite difficult.

I have a rather silly question: in what way does the level of internal water affect the pulp-forming properties? Does it influence whether the concentration can be achieved, and is it definitely related to the internal water? It’s a problem related to the quality of the coal itself; it should be determined through slurry formation tests, right? There is also a high ash content, which will definitely affect the amount of wastewater that needs to be treated. As for whether scaling occurs or not, it would be necessary to examine the chemical composition of the coal ash; I think it is related to the amount of calcium present. Hope for some advice

The coal quality characteristics you mentioned seem to be typical of lignite. Currently, the gasification of lignite is considered an advanced technology, and there is still debate as to which gasification method is the most suitable. Dry gasification can be used for lignite, but it is difficult to dry the coal; to determine whether slurry gasification is appropriate, it is necessary to analyze the properties of the slurry. If the pores in the coal are sealed after coking, then slurry gasification is a viable option; if they are not sealed, adding water results in a slurry concentration that is not high enough, making this method less economical.