Coal-fired gasifier combined with anti-burning point porcelain
The gasification furnace mainly adopts coal water slurry feed and pure oxygenation process, and has the advantages of high carbon conversion rate, good gas quality, suitable for chemical synthesis of raw gas, convenient disposal of three wastes, and remote control of computers. However, the process conditions for coal-water slurry gasifiers are quite strict, and the operating temperature is above the coal ash melting point. The working conditions are: high temperature (12501550), high pressure (28.5 MPa), strong reducing atmosphere and liquid acid slag, accompanying Solids, liquids, and gases adjust flushing, and there are large fluctuations in temperature and pressure during startup and shutdown. These impose stringent requirements on lining fire facing refractories: (1) Must have high resistance to slag penetration and aggressiveness; (2) Have higher hot strength to improve erosion wear resistance; (3) Has good thermal shock resistance to withstand temperature fluctuations, reduce cracks and flaking of refractory materials; (4) has a suitable volume stability, so that the gasifier in the temperature and pressure fluctuations in the process of better integrity.
The chrome-alumina-zirconium brick gasifier for gasification furnaces is generally cylindrical. The steel shell is composed of 26 layers of different types of refractory materials and is composed of concentric-circular integrated furnace linings. The fire-facing surface is a high-chromium refractories. High-chromium refractories for gasifiers date back to the 1970s. The literature has pointed out that the effect of w(Cr2O3)>75% is better in high-chromium refractories for gasifiers. Research and industrial applications show that only Cr2O3-Al2O3, Cr2O3-Al2O3-ZrO2, and Cr2O3-MgO refractories can withstand the gasifier's operating environment for a long time, such as the Harbison-Walker Cr2O3-Al2O3 brick (w(Cr2O3) At 75% and 90% respectively, France's SAVOIE's Cr2O3-Al2O3-ZrO2 bricks (w(Cr2O3) are 80% and 90%, respectively), and Radex's chromiummagnesia spinel brick (w(Cr2O3) is 80 %)Wait. When China introduced the first set of Texaco gasifiers, it did not have the ability to produce gasifiers facing fire bricks. Therefore, the linings were also imported. The Zirchrom80 bricks from SAVOIE of France were used as facing bricks, but the prices were comparable. Expensive, accounting for about 40% of the cost of imported equipment. However, SAVOIE's chromium-aluminum-zirconium bricks have a service life of only half a year at the Lunan Fertilizer Plant gasifier. Later, when the Tie River Fertilizer Plant was introduced with Texaco gasifiers, it also used the French Chrome AZZ bricks from SAVOIE. However, the service life of the 3 gasifiers was only 3900h, 2300h and 3100h, respectively.
When Shanghai Coking Co., Ltd. introduced the Detugu gasification furnace, the lining refractories also used the French chromium chromium aluminum zirconium brick (Zirchrom 90), the average service life of the gasifier is 8000h. Because the foreign chromium aluminum zirconium brick The effectiveness of domestic gasifiers varies from one manufacturer to another, and its cost is relatively high. Therefore, domestic research on high-chromium refractories for gasifiers has begun.
The cause of the destruction of the gasifier was analyzed through laboratory work and analysis of the residual bricks of the chrome-aluminum-zirconium bricks. There are usually two types of damage to the chromium-aluminum-zirconium bricks on the fire surface, ie, erosion and spalling. Erosion occurs when the refractory material dissolves in the slag, or when the bonded phase of the refractory material is dissolved on the surface of the fire, the refractory particles fall off into the slag. For high-chromium refractory linings, this type of damage is continuous and slow. Peeling occurs at a certain stage, and it is a large-scale exfoliation of the refractory material at the surface of the fire to the flowing liquid slag. Refractory material damage caused by erosion and spalling is shown at different times.
The slag corrosion test work shows that the depth of penetration of iron oxides in the slag into the refractory material is not deep and is only limited to the interface. However, the depth of penetration of CaO, Al2O3, SiO2 in the slag in the refractories is deeper. The relative depth of the elements in the slag penetrates into the chrome-aluminum-zirconium bricks.
Although erosion and spalling are the main reasons for the destruction of refractory materials, there are other erosion mechanisms in the actual operation of the gasifier, such as the erosion of hot gases or the accumulation of salt. The current status of refractory materials for gasification furnaces Since the development and application of Cr2O3 refractory materials in the 1970s, due to the technical complexity of the gasification furnace and the relatively small market, there is no significant technological advancement in this refractory material. In order to extend the lining life of the gasifier, and also to realize the localization of chromium aluminum zirconium bricks for gasification furnaces, some domestic manufacturers successfully developed chromium aluminum zirconium bricks suitable for use in domestic gasifiers.
An example of the use of chromium aluminum zirconium bricks produced by a domestic plant on the gasifier is as follows: In 2001, a new C gasifier was installed in Lunan Chemical Fertilizer Plant. The service life of the cylinder was 13,000 hours, and the service life of the cone bottom was 8729 hours. In 2005, Shaanxi Shenmu Chemical Industry Co., Ltd. established a new 600,000 t methanol project. The lining structure and brick design of the 3 gasifier adopt the design scheme of the plant, and a full set of refractories is also provided by the plant.
At present, the service life of chrome-aluminum-zirconium brick produced by this plant in Shanghai Coking and Anqi Huai Chemicals gasification furnaces is 8000h and 14106h, respectively.
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