【Major Equipment in the Chemical Equipment Industry】362—High-frequency ball valves have been successfully replaced with domestic alternatives in Sichuan Petrochemical’s polypropylene production facility project
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This post was last edited by Desert Fish on 2022-6-21 at 15:38. High-frequency ball valves have been successfully replaced with domestically produced ones in the polypropylene production facility of Sichuan Petrochemical. The polypropylene PDS system places very high demands on valves; the medium used in this facility is a gas-solid mixture, and the ultra-fine polypropylene powder has the tendency to aggregate, easily causing blockages in the valve components. This can lead to pipeline blockages, and therefore valves are required to operate frequently – opening and closing every 2–3 minutes, with an operation time of less than 2.5 seconds. This batch of PDS high-frequency ball valves features a large number of units, large diameters, and critical installation locations; in particular, valves D and E are the ones that operate under the harshest conditions and play the most vital role in the polypropylene PDS system. A batch of PDS high-frequency ball valves designed and manufactured by Chongqing Chuanyi Control Valve Co., Ltd. in October 2019 were used to replace imported products in the 450,000 tons per year polypropylene production facility of Sichuan Petrochemical Company in China. Since their installation, they have performed well, earning high praise from the users, who noted that they have \"good sealing properties, stable operation, and performance comparable to that of the original imported high-frequency valves.\"
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The polypropylene plant uses a gas-phase fluidized bed method to produce polypropylene resin. When the reactor meets the discharge conditions, the powder is transferred to downstream processes via the PDS discharge system. The efficiency of this discharge system has a direct impact on the reaction load, making it one of the key systems in the plant. The PDS discharge system operates automatically. During normal production, the powder in the reactor is discharged to the PC tanks through valves A and B. Then, the two PC tanks in the same group are pressure-balanced via valve W. After pressure balancing, the powder is sent to the “PBT tank” through valve D, from where it is then discharged to the downstream processing steps. During the production process, due to factors such as equipment limitations, the fluidization effect in the polymerization reaction system, the amount of catalyst injected, and the system’s heat removal capacity, the temperature of the reactor walls can rise. This can lead to the formation of lumps or flakes, increasing the density of the material in the lower layer of the bed and reducing the efficiency of material discharge, thereby affecting the operation of the plant.
Based on production experience, when a blockage occurs between the PC tank and the PBT tank, resulting in reduced efficiency of the PDS feeding system, a \"backwashing\" procedure is used to resolve this issue. In this process, gas from the PBT tank is used to backwash the PC tank through valve D; the resulting pressure difference blows away the lumps remaining at the conical bottom of the PC tank. Through repeated backwashing operations, the lumps in the PC tank are moved into the PBT tank and then sent downstream. In order to further improve the efficiency of flushing and enhance the operational performance of the equipment, the polypropylene workshop conducted in-depth research on the process based on the characteristics of the PDS discharge system, seeking the best optimization measures. After analyzing various processes and procedures, an optimization method that combines forward flushing and reverse flushing was proposed. Building on the \"backwashing\" mechanism, a method of manually increasing the pressure difference between the pipeline and the transfer tank is added; once the location of the blockage is identified, all the lumps or flakes inside the reactor and the PDS system are blown out.
【Major Industrial Equipment in the Chemical Engineering Sector】Construction begins on the upper module of 360 – the world’s largest FPSO for deep-sea oil fields https://bbs.hcbbs.com/thread-3359526-1-1.html (Source: Hua Hai Chuan Liu – Haichuan Chemical Industry Forum)