The production process of polycrystalline silicon is rather complex and has specific requirements for valve limit switches. In the production of polycrystalline silicon, due to the involvement of various chemical substances and complex process conditions, valve limit switches need to have good corrosion resistance to cope with the erosion of strongly corrosive substances such as chlorine gas and hydrofluoric acid. At the same time, as there may be high-temperature and high-pressure situations during the production process, valve limit switches also need to have the characteristics of withstanding high temperatures and high pressures to ensure their stable and reliable operation.
For instance, in the tendering project of adding solenoid valves and limit switches to the bellows control valves in the 60,000 tons per year polycrystalline silicon project of Zhunneng, strict requirements were put forward for the related equipment, including basic qualification conditions such as having an independent legal person status and the ability to fulfill the contract, and not being in an adverse state such as being ordered to suspend business or having assets taken over. In the relevant materials of the dry separation system technology for the reduction tail gas of polycrystalline silicon, high requirements for the performance and quality of various components in the system, including valve limit switches, were also mentioned.
In addition, there are also some problems in the use of valves in polycrystalline silicon. For example, in the silicon powder transportation link, the ball valve is prone to being wrapped by silicon powder, causing damage and leakage of the metal seal. Frequent opening may also damage the ball valve, resulting in failure to close and causing backflow of high-pressure gas. Therefore, the valve limit switches used in polycrystalline silicon production need to have characteristics such as high wear resistance, high precision, and long service life to meet the needs of the complex production process of polycrystalline silicon.
Corrosion Resistance Requirements of Valve Limit Switches in Polycrystalline Silicon Production
During the production of polycrystalline silicon, the environment is complex with multiple chemical substances. Valve limit switches need to have excellent corrosion resistance to cope with these harsh conditions. In the manufacturing environment of polycrystalline silicon, there may be corrosive substances such as strong acids and strong alkalis. For example, some chlorides produced during production may have strong corrosivity. To ensure the long-term stable operation of the limit switch, the selection of its materials is crucial. Usually, special alloy materials or specially treated surface coatings are adopted to enhance its corrosion resistance. These materials can not only resist common chemical corrosion but also deal with electrochemical corrosion caused by temperature changes. For example, certain stainless steel alloys exhibit good corrosion resistance in chlorine-containing environments and are widely used in valve limit switches in polycrystalline silicon production.
High Temperature and High Pressure Resistance Requirements of Valve Limit Switches in Polycrystalline Silicon Production
Polycrystalline silicon production often occurs under conditions of high temperature and high pressure. Valve limit switches need to maintain stable and reliable performance in this environment. High temperatures may cause the degradation of material properties, such as softening, deformation, or even loss of strength. While high pressure poses a severe challenge to the structure and sealing of the switch. Generally speaking, limit switches that can adapt to polycrystalline silicon production need to be able to operate normally at several hundred degrees Celsius and relatively high pressures. For example, some special ceramic materials or high-temperature resistant alloys can withstand high temperatures without deformation, and their sealing structures are also carefully designed to ensure no leakage under high pressure. In addition, good heat dissipation design and insulation measures are also key to ensuring the normal operation of limit switches in high-temperature environments.
Wear Resistance Requirements of Valve Limit Switches in Polycrystalline Silicon Production
In polycrystalline silicon production, due to the particularity of the process, the actions of valves are rather frequent, which poses very high requirements for the wear resistance of limit switches. Frequent friction and collisions can easily lead to the wear of switch components, affecting their accuracy and reliability. To improve the wear resistance, the key components of limit switches usually adopt materials with high hardness and excellent wear resistance. For example, using hardened metal components or high-performance composite materials. At the same time, optimizing the structural design of the switch to reduce the contact area and pressure of the friction parts can also effectively improve the wear resistance. Some advanced surface treatment technologies, such as carburizing and nitriding, can further enhance the surface hardness and wear resistance of the materials and prolong the service life of the limit switches.
Precision Requirements of Valve Limit Switches in Polycrystalline Silicon Production
The production of polycrystalline silicon has extremely high requirements for process precision, which directly affects the precision of valve limit switches. High-precision limit switches can accurately control the stroke of the valve to ensure the stability and consistency of the production process. In the manufacturing of polycrystalline silicon, even tiny errors may lead to the decline in product quality or the reduction in production efficiency. To meet the requirements of high precision, the manufacturing process of limit switches needs to be very fine, and the sensitivity and accuracy of the sensors need to undergo strict testing and calibration. For example, adopting advanced photoelectric sensors or high-precision mechanical contact sensors can precisely sense the position changes of the valve. At the same time, cooperating with a precise control system to achieve precise control of the valve actions.
Service Life Requirements of Valve Limit Switches in Polycrystalline Silicon Production
In polycrystalline silicon production, due to the continuity and complexity of production, valve limit switches need to have a long service life. Long-term operation and frequent actions are a huge test for the durability of the switch. To meet the requirements of long service life, in addition to selecting high-quality materials and advanced manufacturing processes, strict quality inspection and reliability testing are also required. For example, fatigue tests simulating actual working conditions are conducted during the production process to verify the stability of the switch during long-term use. In addition, regular maintenance and servicing are also important measures to prolong the service life of the limit switch, including cleaning, lubrication, and inspection of the wear of components, etc.
The requirements for valve limit switches in polycrystalline silicon semiconductor production are very strict and diverse. The requirements of corrosion resistance, high temperature and high pressure resistance, wear resistance, precision, and service life are all crucial. Only by meeting these requirements can valve limit switches operate stably and reliably in polycrystalline silicon production, ensuring the smooth progress of production and the quality of products.