In a five-star hotel, a direct drinking water system with a capacity of 1000 m³/day utilizes hollow fiber ultrafiltration membranes. These membranes have an outer diameter of approximately 1 mm and an inner bore of about 0.7 mm. Raw water passes through the fiber's inner holes under pressure, and water permeates through the membrane pores to form ultrafiltrate, which is collected from the filter outlet. The hollow fiber membrane does not require any support structure, making the filtration device simple in design, cost-effective, and highly efficient. Compared to plate-type membranes, the performance of hollow fiber membranes is about 20 times higher in terms of water treatment per unit volume.
The treatment process includes: tap water → raw water tank → sand filtration → activated carbon → softening → fine filtration → clean room → final storage. Sand filtration effectively removes most suspended solids (effluent SS can reach up to 2 mg/L), while using a 5 μm precision filter can bring SS down to 0.1 mg/L and reduce the pollution index (FI) to 3–5. Activated carbon and ion exchange resins help remove residual chlorine, organic matter, and divalent ions like calcium and magnesium, improving water taste and quality.
The system uses two ultrafiltration units, each containing 36 membranes divided into two groups of 18. During operation, the system adjusts the cycle time based on water production, performs isobaric washing, and ensures the membrane returns to normal operation. Backwashing is highly effective but requires ultrafiltered water as the cleaning medium. To achieve this, the system alternates between groups for backwashing—Group A washes Group B, and vice versa.
Each ultrafiltration module has dimensions of 90 mm × 1000 mm and contains around 2,000 hollow fiber membranes with a total area of approximately 4 m². The membrane material is polyvinylidene fluoride (PVDF), known for its excellent chemical stability and resistance to fouling, outperforming common materials like PS or PAN. Despite its advantages, practical applications still face challenges, especially in membrane cleaning and maintenance. Key issues include determining the right cleaning timing, methods, and chemicals to ensure long-term performance and lifespan.
To meet the high demand for continuous, stable water supply for direct drinking, the system was designed with an "Automated Ultrafiltration Equipment with Microcomputer and Pneumatic Diaphragm Valve." This system automates the entire process, including work, isobaric washing, backwashing, and chemical cleaning. It uses a microcontroller (89C51) as the core control unit, integrated with pneumatic diaphragm valves to manage the filtration modules. Operators can set the program times via a keyboard, such as "water intake → isobaric washing → backwash → chemical cleaning."
The pneumatic diaphragm valve plays a crucial role in the automated system. Unlike manual valves, it operates using compressed air, with a two-part structure: an upper air chamber and a lower liquid chamber. When pressurized, the diaphragm moves to close the valve; when the pressure drops, it reopens due to the return force of the elastic bowl. The valve body is made of ABS plastic, offering good mechanical, chemical, and thermal properties without affecting water quality. High-quality rubber and reinforced internal cords are used for durability.
One key advantage of membrane filtration is the high-speed lateral flow on the membrane surface, which prevents impurities from settling and reduces fouling. However, this leads to significant water loss. Typically, only 90% of the water is utilized, with 10% discharged. To improve efficiency, a reuse system was added, increasing the recovery rate to 98.7%. Only 1.3% of the water is discharged during automatic cleaning. The concentrated water is redirected to an intermediate tank and continuously fed back into the ultrafiltration system along with the filtered water.
In conclusion, ultrafiltration, combined with sand filtration, activated carbon, softening, and fine filtration, successfully meets all water quality standards, including total bacteria (<50/mL) and coliforms (<3/L). After one year of operation, the system has performed reliably, and the self-developed ultrafiltration equipment with microcomputer control and pneumatic diaphragm valves has proven stable and suitable for large-scale applications.
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A Tower Crane trolley is a component of a tower crane that moves horizontally along the jib of the crane. It is a wheeled device that is attached to the jib and is used to move the load from one location to another. The trolley is controlled by the operator using a remote control or a cabin located on the crane. The trolley is an essential component of the tower crane as it allows the operator to move the load precisely and safely. It is designed to withstand the weight of the load and the forces generated during the lifting process.
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