Operation of the Aerospace Furnace at Tianxi Coal-to-Oil Branch in 2016
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In 2016, the Tianxi Coal-to-Oil Branch of Shanxi Jincheng Smokeless Coal Mining Industry Group Co., Ltd. produced 300,000 tons of methanol, thus fulfilling its annual production target. The plant’s operational rate was 92%, with continuous operation for 97 days; the consumption of raw coal was 1.55 tons (the designed value being 1.62 tons), and the coal consumption per ton of methanol produced was 0.55 tons. The raw coal used by the Tianxi Coal-to-Oil Branch is \"high-sulfur, high-ash, and high-carbon\" coal. The original design called for the use of ash fusion gasification technology; however, due to the limitations of this technology, the operating load of the facility was not high. To this end, a space furnace was used for modification. Taking into account the characteristics of coal in Jincheng, Shanxi, the aerospace company optimized the design of the aerospace furnace. First, make adaptive improvements to the furnace chamber and slag outlet of the gasifier ； Secondly, some targeted adjustments are made in response to the high ash content and high ash fusion point. In 2014, 2 space furnaces were put into operation. Once the space furnace is put into operation, it uses entirely Jincheng’s \"high-grade\" anthracite, marking a breakthrough in China’s use of anthracite as the sole fuel. According to operational statistics, Gasifier No. 1 was in operation for 329 days in 2016, while Gasifier No. 2 was in operation for 315 days. Currently, both space furnaces are operating at full capacity and stably; the daily methanol production is 1,050–1,100 tons, and the maximum daily processing capacity for raw coal is 1,900 tons. All performance indicators meet or exceed the design values.
Judging from the description, it seems to be true; it is said that the sludge water system still needs optimization
Isn’t Jinmei working on a Jinmei furnace with Huali?
That’s right; it seems a lot of work has already been done regarding their bituminous coal.
What are the main problems? Problems with bituminous coal raw materials?
What is the carbon conversion rate? Is the residual carbon in the ash high?
Is the consumption of raw coal and fuel coal expressed in standard coal?
I visited the Tianxi coal-to-oil project last year, and it faced quite a number of problems. The coal used for gasification in this project has a high silicon content, which results in an excessive level of silica in the ash water and an increase in its turbidity. This leads to severe blockages in the pipes running from the quench chamber and wash tower to the high-flash point device; in severe cases, only a narrow channel remains in the middle of these pipes. The main cause of this problem is an excessive silicon content, and silica exists in the form of silica gel colloids under weakly acidic conditions. The slurry in the quench chamber is generally weakly acidic, which can easily lead to pipe blockages.
This is the first time I’ve heard of a substance that is produced through gasification to form silica gel; the silicon dioxide content in the anthracite ash from Jincheng seems to be around 42%. Are there no similar situations in other projects? How did Tianxi solve this problem?
The general formula for silicic acid is xSiO2·yH2O; it is a hydrate of amorphous silica. A white, jelly-like or flocculent solid. The composition of silicic acid is complex and often varies depending on the conditions of its formation. The silicon acids that have been identified to date are: metasilicic acid H2SiO3 (x=1, y=1), disilicic acid H2Si2O5 (x=2, y=1), pyrosilicic acid H6Si2O7 (x=2, y=3), and orthosilicic acid H4SiO4 (x=1, y=2). When the values of x and y are large, these substances are actually polymers of SiO2; as the degree of polymerization increases, their solubility in water decreases, resulting in the formation of silica gel, which is what is commonly referred to as colloidal silicon. Colloidal silicon and dissolved silicon can be converted into each other, with the conversion conditions depending on the pH of the water. The higher the PH, the easier it is for colloidal silicon to convert into dissolved silicon. For example, at pH=6.0, the solubility of silicic acid is 0.005 mmol/L ； At PH=7, the solubility is 0.05 mmol/L. The existence form and composition ratio of silicates are related to the pH of water: pH 5, 6, 7, 8, 9, 9.5, 10, 11, 12, 12.9 – H2SiO3: 100, 100, 99.7, 96.9, 75.8, 49.6, 23.5, 2.6, 0.1; 0 HSiO3-: /, /, 0.3, 3.1, 24.2, 50.2, 75.3, 84.0, 38.4, 7.3; SiO32-: /, /, /, /, /, 0.2, 1.2, 13.4, 61.5, 92.7. In a quench chamber, the pH is generally between 4 and 6; therefore, all silicate compounds in the water exist in the form of silica gel, which can easily lead to silica gel precipitation and blockage of pipes. Moreover, colloidal substances have a very large specific surface area, which makes it easy for them to adsorb dispersants and coagulants, thereby reducing the effectiveness of these chemicals and ultimately leading to a vicious cycle. The gray water that overflows from Tianxi’s sedimentation tank is somewhat whitish in color, mainly due to a high level of colloidal substances, which remain stable.