Many large-scale desalination projects are under construction in the country. This article starts from the media, materials, anticorrosive treatment, structure and installation requirements, and analyzes the choice of process valves in desalination project engineering design. Process media desalination process, the need for special attention to chloride corrosion of equipment. In addition, the seawater temperature has a great effect on the corrosion rate, the higher the temperature, the faster the corrosion. Solid contaminants can damage the protective film and cause erosion. Various types of chemical contaminants can also increase the probability of corrosion. Ingredient Additives may be a man-made sea chemicals chemical pollutant, but from the corrosion point of view, the amount does not cause any problems. Sodium hypochlorite is sometimes used to inhibit algae, but too much dosage can cause severe pitting corrosion. Seawater desalination There are a variety of processes, of which the main reverse osmosis process for the sea water → pretreatment → ultrafiltration → reverse osmosis → product water (by-product of reverse osmosis concentrate), the main medium of the composition of the process shown in Table 1 ( Different seawater intake at different locations). Valve material In desalination project, valve material problems appear in the overcurrent components. At present, the commonly used flow components are mainly nickel aluminum bronze, stainless steel, duplex stainless steel and metal coating. Valve type Reasonable choice of valve type, can reduce material consumption, reduce local resistance and energy consumption, ease of installation, reduce maintenance. This article focuses on the choice of large-diameter shut-off valves and check valves. Shut-off valve Large desalination process diameter is generally DN300 ~ 1600, beyond the general range of ball valves and globe valves. Compared with the same diameter gate valve (Z41H), the butterfly valve has the advantages of simple structure, easy anti-corrosion, short installation length, less consumption of steel, and similar partial resistance coefficient of the valve. It is more economical and practical to choose the butterfly valve as the shut-off valve. According to the pressure level, the butterfly valve can be divided into low pressure butterfly valve and high pressure butterfly valve.
Thread Rolling Machine
The thread rolling machine is a multifunctional cold extrusion forming machine. The thread rolling machine can process the workpiece in the cold state under the rolling pressure range, such as threading, straight graining and twill rolling; straight gear, helical gear and diagonal spline gear Rolling; straightening, reduction, rolling, and various forming rolls. The machine features a safe and reliable electro-hydraulic actuator and control system that can be selected in manual, semi-automatic and automatic modes.
The rolling cold rolling process is an advanced non-cutting process, which can effectively improve the internal and surface quality of the workpiece, and the radial compressive stress generated during processing can significantly improve the fatigue strength and torsional strength of the workpiece. The ideal process for energy saving and low consumption.
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