Application of titanium and titanium alloy in vacuum salt making equipment

In the vacuum salt system, the raw material is brine, which contains a lot of corrosive medium. Its main equipment, such as brine preheater, heater and evaporation tank, is exposed to high-concentration brine for a long time at a high temperature and constantly impacted by salt and sand. Under such conditions, the equipment should operate normally for a long time, and anti-corrosion is the key problem. There are many reasons for corrosion, among which the presence of O2, high temperature, Cl- and solid salt scouring are the main factors. The widely used anticorrosive methods include deoxygenation, pH adjustment, electrochemical protection, coating protection and anticorrosive materials. The use of anticorrosive materials is a very effective way of anticorrosion, and the application of titanium and titanium alloys in vacuum salt production is one of them. Preheater raw materials should be preheated before entering the heater to save energy. Preheater used to use tubular heat exchanger, heat exchange tube material made of carbon steel, easy to plug, corrosion through the pipe, often need to change the heat exchange tube, stop maintenance, which brings great inconvenience to production. There are also preheaters with red copper pipes, the corrosion situation still exists, the service life is extended to 1 year, but it is still very short, and the cost of red copper pipes is high. Until the titanium plate heat exchanger came along. The heat exchange surface of plate heat exchanger is plate, although the strength is not as good as the tube heat exchanger, but its heat transfer effect is good, less material, light weight, easy to maintain, its life can be up to 15 years. For example, the pure titanium plate heat exchanger used by Zigong Zilujing salt factory has been used since 1994, the titanium plate is still bright as new, never replaced, and the economic benefits are obvious. Because the heater heat exchange tube is densely arranged on the tube plate, the maintenance and repair of the heater is quite time-consuming, and the heating tube needs to be replaced once a year. Ⅱ effect, Ⅲ effect temperature is lower, the heating tube can be used for about 2 years. Ⅳ effect temperature can only be used for 4 years to replace the minimum, overhaul downtime delay production, production is reduced, production is seriously affected, and maintenance costs are high (some manufacturers will use copper for heating chamber, the situation has improved, but I effect service life is only 3-5 years). In view of the characteristics of titanium, if titanium is used in the heater, the situation will be greatly improved.