China has overcome the technical barriers related to the production of high-concentration water-coal slurry from low-grade coal; costs in the coal chemical industry are expected to decrease significantly
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This post was last edited by Tianya Langji on 2009-11-12 at 11:22. China has overcome the technical barriers related to the production of high-concentration water-coal slurry from low-cost coal, which will significantly reduce the costs for coal chemical enterprises. After 14 years of research, the Western Shaanxi Yulin Coal Technology Research Center has finally overcome the global challenge of low-grade coal’s difficulty in being converted into a slurry and of producing high-concentration water-coal slurry. It has developed a technology for preparing high-concentration water-coal slurry from fine dry powder of low-grade coal, along with a complete set of production processes. On November 8, the center signed a project cooperation agreement with Shanxi Coal Group Shennan Zhangjiamao Mining Co., Ltd., covering a total investment of 90 million yuan and an annual production capacity of 2 million tons. **More than a dozen experts, including Zhan Long, former director of the Water-Coal Slurry Engineering Center and a professor-level senior engineer; Wu Guoguang, dean of the School of Chemical Engineering at China University of Mining and Technology; and Li Baoqing, a researcher at the Shanxi Institute of Coal Chemistry under the Chinese Academy of Sciences, are of the unanimous opinion that the technology for producing high-concentration water-coal slurry from low-grade coal in fine dry powder form, along with the corresponding production line developed by the Yulin Western Coal Technology Research Center, has overcome the technical barriers associated with using low-cost coal to produce high-concentration water-coal slurry, reaching an internationally advanced level. Experts recommend accelerating its promotion and application on the basis of further improving relevant security technical measures. Experts point out that this achievement will play a positive role in promoting the development of the new clean coal chemical industry, which is driven by the pressurized gas generation technology using water-coal slurry. In particular, the use of this technology to increase the concentration of water-coal slurry will significantly reduce the costs for coal chemical enterprises. Taking a 600,000 tons per year coal-to-methanol plant as an example, by using new technology to increase the concentration of coal water slurry from 62% to 72%, it is possible to produce 50,000 more tons of methanol per year, reduce oxygen consumption by 84 million cubic meters, and cut coal consumption (including coal equivalent to that used for power generation) by 21,000 tons. This results in cost savings and increased efficiency worth over 13 million yuan; the economic, energy-saving, and environmental benefits are very significant. Low-grade coal is the type of coal that has been formed over the shortest period of time and undergoes the least degree of coalification; its difficulty in being used to produce high-concentration water-coal slurry limits its application in chemical manufacturing. Previously, the highest concentration of water coal slurry produced domestically and internationally using low-rank coal as a raw material could only reach 59%; achieving a high concentration of over 65% with good rheological properties has always been a global challenge. He Feng, the chief engineer of the Yulin Western Coal Technology Research Center, led his team to conduct research on the production of high-concentration water-coal slurry from low-rank coal starting in 1995. The center invested 40 million yuan to purchase testing equipment and analysis facilities. Using five types of low-rank coal, including lignite, with an internal moisture content of 25%-43%, it conducted 56,000 repeated tests and made multiple improvements to the testing equipment. As a result, it developed a technology for producing high-concentration water-coal slurry from fine dry powder of low-rank coal, along with a complete set of production processes, enabling the creation of water-coal slurry with a concentration of 67.8%-72.0%, a viscosity of 590-900 millipascal·seconds, and excellent stability. Furthermore, using the Baorixile lignite, which is the most difficult to convert into slurry, the center has produced water coal slurry with a concentration of over 65%, a viscosity of less than 1,200 millipascal-seconds, and good stability, thereby overcoming the global challenge of producing high-concentration water coal slurry from low-grade coals. http://www.16ds.com/papers/4912/topics/49675
The poster’s news is truly worth celebrating: I would like to ask whether the requirements regarding the ash fusion point of coal in the production of coal slurry change during pressurized gasification, and whether coal with a high ash fusion point can be used in the Texaco gasification process.
It is said that GE is also working on this in Shenmu; it is claimed that they can increase the concentration of coal slurry to 80%. If this has been achieved domestically, it is indeed something worth celebrating. Those days of powder coal gasification, especially with foreign technologies, were not easy at all, haha
This post was last edited by robinbird on 2009-11-11 at 15:42. The result is amazing – what about the gradation after dry grinding? Most coal slurry plants currently use wet grinding; will the entire process need to be changed in the future? Also, I have doubts about the data inside. The news said that the internal moisture content of the lignite used was as high as 25%-43%, but the concentration of the coal slurry obtained later was as high as 67.8%-72%? How is this calculated? As we all know, internal water is difficult to remove; with such a high level of internal water already present, it’s surprising that the coal slurry concentration is still so high. If this is true, with no external water added and a large portion of the internal water having been removed? Or does most of the internal water precipitate as external water? Or is it that most of the internal water is dried out, then water is added, or some substance is added to prevent external water from turning into internal water? Also, to remove the internal water, a large amount of heat is definitely required – what is the cost associated with this energy consumption? If anyone knows this technology, please come forward and give some guidance
This news seems really inspiring. But if you think about it carefully, just like the friend upstairs, there are indeed many doubts. 1. Based on the article, it seems that grinding follows pulping; so what are the requirements for the raw coal before grinding? Especially, what are the requirements regarding moisture? 2. The cost issue of additives. Water-coal slurry definitely requires additives, but I’m not sure if the additives used here are expensive 3. The moisture content of ordinary lignite is generally between 20% and 30%. If the concentration of the water-coal slurry can reach 70%, is it then unnecessary to add water during slurry preparation? Should it still be done as mentioned above, by first drying and grinding it, and then adding water to make a pulp? 4. If lignite-based slurry production can achieve such good results, then technology for producing high-concentration coal slurries from bituminous coal should also be developed. After all, this seems to be less difficult; bituminous coal has a higher calorific value and gas generation rate, and success in this area would have a greater impact on the advancement of water-coal slurry gasification. Who knows, maybe Shell will have to stop operating in this field eventually :) (Just joking.)
Simple pulping is not a problem; this technology has been used in many coal-fired boilers for a long time. However, when applied to gasification, cost considerations must be taken into account, and as far as I know, the costs are still quite high. The original poster can talk about the situation in this regard.
After gasification using Texaco’s technology, the resulting mixture contains more carbon and less hydrogen; hydrogen comes mainly from the moisture in the coal slurry. By increasing the concentration of the coal slurry from 62% to 72%, the moisture content decreases, which in turn reduces the amount of hydrogen available for methanol synthesis. So how can methanol production be increased?
When engaging in industrial activities, it is essential to pay attention to technical economics! No matter how good the technology is, high costs still mean that it is not practical to use; Iridium in the United States is a testament to this!
Raising the concentration to 72% is indeed very encouraging; I hope the subsequent work will progress smoothly. Looking forward to it. . .
The last edit to this post was made by hjy2000 on 2009-11-12 at 18:09. It is not difficult to understand that increasing the concentration of water-coal slurry can boost methanol production; when water-coal slurry is gasified, a large amount of water remains unutilized – in fact, only slightly over 20% of the total water participates in the gasification reaction, while the rest turns into steam after absorbing heat, and then exits along with the process gas. Therefore, increasing the concentration of the water-coal slurry does not lead to a decrease in the hydrogen content in the process gas; on the contrary, it significantly reduces the specific oxygen consumption and specific coal consumption, as well as increases the production capacity of each furnace. Thus, as long as the viscosity of the water-coal slurry does not increase significantly, raising its concentration is undoubtedly beneficial with no drawbacks!
Texaco used the dry milling and wet mixing process as early as 1948, but stopped using it in 1958 due to scaling issues and wear