Titanium metal has excellent corrosion resistance and mechanical properties and is widely used in many sectors. Especially in chemical applications, titanium can be used as a corrosion-resistant material instead of stainless steel, which is of great significance in extending the service life of equipment, reducing costs, preventing pollution, and improving productivity. In recent years, the scope of titanium used in my country's chemical industry has been continuously expanding, and its usage has increased year by year. Titanium has become one of the main anti-corrosion materials in chemical equipment. As a corrosion-resistant structural material used in chemical equipment, titanium has become an ideal material in chemical equipment.

Chlor-alkali industry

The chlor-alkali industry is an important basic raw material industry, and its production and development have a great impact on the national economy. This is because titanium's corrosion resistance to chloride ions is better than commonly used stainless steel and other non-ferrous metals. At present, titanium is widely used in the chlor-alkali industry to manufacture metal anode electrolyzers, ion membrane electrolyzers, wet chlorine coolers, refined brine preheaters, dechlorination towers, chlorine gas cooling and washing towers, etc. In the past, the main components of these equipment were mostly made of non-metallic materials (such as graphite, polyvinyl chloride, etc.). Due to the unsatisfactory mechanical properties, thermal stability and processing performance of non-metallic materials, the equipment was bulky, energy-consuming and short-lived. , and affect product quality and pollute the environment. Therefore, since the 1970s, our country has successively replaced graphite batteries with metal anode batteries and ion membrane batteries, and replaced graphite coolers with titanium wet chlorine coolers, all of which have achieved good results.

For example: Application of titanium wet chlorine cooler. The electrolysis of salt to produce caustic soda produces a large amount of high-temperature wet chlorine gas. The temperature is generally between 75 and 95°C, and it needs to be cooled and dried before it can be used. In the past, the production of chlorine produced by electrolysis of table salt in my country had affected the output and quality of chlorine due to unreasonable cooling process or corrosion problems of cooling equipment, and also seriously polluted the environment. Titanium coolers resistant to corrosion by high-temperature wet chlorine gas were put into production, changing the production face of chlorine production in the chlor-alkali industry. Titanium is extremely resistant to corrosion in high-temperature, wet chlorine environments. In chlorine water at room temperature, the corrosion rate of titanium is 0.000565mm/a; in chlorine water at 80°C, the corrosion rate of titanium is 0.00431mm/a; in chlorine water containing 95% In wet chlorine gas, the corrosion rate of titanium at room temperature is 0.00096mm/a. Many chlor-alkali plants often use titanium wet chlorine coolers, some of which have been used for nearly 20 years and are still in good condition.

Soda ash industry

Soda ash is one of the most basic chemical raw materials, which is directly related to the development of the national economy. In the process of soda ash production, the gas media are mostly NH3 and CO2, and the liquid media are mostly NaCl, NH4Cl, NH4HCO3 and Cl- solutions with higher concentrations. Carbonization tower tubes and hot mother liquor coolers made of carbon steel and cast iron are used for the carbonation reaction. , cooler, crystallization external cooler and other main equipment are not resistant to corrosion, have serious corrosion leakage, and have a service life of no more than three years. From 1975 to 1977, Tianjin Alkali Plant and Dalian Chemical Industry Company built factories to conduct titanium application demonstration work, including carbonization tower cooling pipes of 63×2mm, titanium flat plate heat exchangers, titanium external coolers, titanium pumps, and CO2 turbine compressor rotors. , Ti-6Al-4V alloy impellers, etc. have been applied to good effect, which has served as a model for the entire industry to use titanium technology to transform and build three soda ash plants with an annual output of 600,000 tons.

For example: the ammonia condenser at the top of the distillation tower of a soda ash plant should use pure titanium pipes instead of cast iron pipes. The ammonia condenser is a device used to condense the ammonia steamed out of the distillation tower during the soda ash production process. It consists of two cast iron cooling boxes. Each box has a diameter of 2.5m and a height of 1.2m. The box is originally equipped with Φ63×6 214 x 2986mm cast iron small pipes, 428 pieces in total in two boxes. The inside and outside of the pipe are anticorrosive with thermosetting phenolic varnish. The medium outside the pipe is NH3, CO2, H2O steam, and the temperature is about 95°C. The NH4Cl mother liquor flows through the tube and exchanges heat with the medium outside the tube. Under these conditions, the cast iron pipes were seriously corroded. Some pipes were corroded and perforated after one year of use. After two years of use, they were seriously corroded and damaged and were stopped from use. In order to solve the serious corrosion problem of cast iron pipes in the ammonia condenser, all cast iron pipes were replaced with TA2 titanium pipes with a specification of Φ60×2×3010mm. The ends of the titanium pipes and the cast iron flower plates were sealed with O-type rubber rings. This is the first distillation tower in my country's soda ash industry to use pure titanium tubes for its cooling tubes. After being put into production for more than two years, the pipes were taken out for macro inspection and no corrosion was found. The service life is expected to be more than 20 years, which is 10 times longer than that of cast iron pipes. Because the titanium tube is corrosion-resistant, the heat transfer efficiency remains good (cast iron pipes have good heat transfer efficiency in the early stage, poor mid-term, and failure in the later stage during a three-year overhaul period). The NH4Cl mother liquor in the tube is preheated to recover heat and improve the efficiency of the mother liquor entering the distillation tower. temperature, can save a lot of steam, and the economic benefits are obvious.