Many large-scale desalination projects are under construction. This paper analyzes the selection of process valves in the process of engineering design of seawater desalination projects from the aspects of media, material, anti-corrosion treatment, structure and installation requirements.
Process Medium
In the process of seawater desalination, special attention should be paid to the corrosion of chloride to equipment. In addition, the seawater temperature has a great effect on corrosion rate, the higher the temperature, the faster the corrosion. Solid contaminants can damage the protective film of the material and cause erosion and corrosion. Various chemical contaminants also increase corrosion rates. Ingredient additives may be a man-made marine chemical contaminant, but in the right amount they do not cause any problems from a corrosion standpoint. Sodium hypochlorite, for example, is sometimes used to inhibit algae, but in large doses it can cause severe pitting. There are many processes in seawater desalination, among which the main process of reverse osmosis is seawater intake → pretreatment → ultrafiltration → reverse osmosis → product water (by-product reverse osmosis concentrate) .
Valve Material
In seawater desalination engineering, valve material problems often appear on the flow parts. At present, the commonly used materials for over-current components are mainly nickel-aluminum bronze, stainless steel, dual-phase stainless steel and metal coating.
Valve Type
Reasonable selection of valve type, can reduce material consumption, reduce local resistance and energy consumption, easy installation, reduce maintenance. This paper focuses on the selection of large diameter cut-off valve and check valve.
Cut-off Valve
The diameter of DN300 to DN1600 in large-scale seawater desalination is beyond the use range of ball valve and globe valve. Compared with the gate valve of the same caliber, butterfly valve has the advantages of simple structure, easy corrosion protection, short installation length, less consumption of steel and similar local resistance coefficient. According to the pressure level, butterfly valve can be divided into low-pressure butterfly valve and high-pressure butterfly valve.
Post time: Nov-25-2021