Application of industrially pure titanium in chemical industry

Titanium metal has excellent corrosion resistance and mechanical properties, and is widely used in many sectors. Especially in chemical applications, titanium can replace stainless steel as a corrosion-resistant materials, which has a very important significance to extend the service life of the equipment, reduce costs, prevent pollution and improve productivity. In recent years, China's chemical industry with the scope of titanium is expanding, the amount of increasing year by year, titanium has become the chemical equipment in the main corrosion-resistant materials. As a kind of corrosion-resistant structural material used in chemical installations, titanium has become an ideal material in chemical equipment.
Chlor-alkali industry
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 the corrosion resistance of titanium 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 electrolyzer, ionic membrane electrolyzer, wet chlorine cooler, refined brine preheater, dechlorination tower, chlorine cooling scrubber tower and so on. In the past, the main parts of these equipments were mostly made of non-metallic materials (e.g. graphite, PVC, etc.), due to the mechanical properties of non-metallic materials, thermal stability and processing performance is not ideal, resulting in bulky and heavy equipment, energy consumption, short service life, and affect the quality of the product and pollution of the environment. Therefore, since the 1970s, China began to use the metal anode tank and ionic membrane tank instead of graphite tank, titanium wet chlorine cooler instead of graphite cooler, have achieved good results.

For example, the application of wet chlorine cooler made of titanium. Salt electrolysis production of caustic soda is to produce a large number of high-temperature wet chlorine gas, the temperature is generally 75 ~ 95 ℃, need to be cooled and dried to use. China's salt electrolysis production of chlorine, previously because of the cooling process is not reasonable or because of the corrosion of the cooling equipment affects the chlorine yield and quality, but also seriously pollute the environment. High-temperature wet chlorine corrosion-resistant titanium cooler into production, changing the face of chlorine production in the chlor-alkali industry. Titanium in the environment of high temperature wet chlorine gas is extremely corrosion-resistant, titanium at room temperature in chlorine water, corrosion rate of 0.000565mm / a; at 80 ℃ in chlorine water, titanium corrosion rate of 0.00431mm / a; containing 95% of the wet chlorine gas, the corrosion rate of titanium at room temperature is 0.00096mm / a. Many chlor-alkali often applied to the titanium system of wet chlorine cooler, and some have been used for nearly 20 years, is still intact. 20 years, still intact.

Soda ash industry
Soda ash is one of the most basic chemical raw materials, it is directly related to the development of the national economy. Soda ash production process, the gas medium is mostly NH3 and CO2, the liquid medium is mostly NaCl, NH4Cl, NH4HCO3 and Cl- concentration of the solution, the use of carbon steel, cast iron carbonation reaction of carbonation tower tubules, hot mother liquor cooler, cooler, crystallization outside the cooler and other equipment, are not corrosion-resistant, corrosion and leakage is serious, the service life of less than three years. 1975-1977, Tianjin Alkali Plant, the main equipment, the main equipment is not corrosion-resistant, corrosion and leakage is serious, the service life of less than three years. -1977, Tianjin Soda Plant and Dalian Chemical Industry Company built a titanium application demonstration work, carbonization tower cooling tube 63 × 2mm, titanium plate heat exchanger, titanium external cooler, titanium pumps, CO2 turbine compressor rotor, Ti-6Al-4V alloy impellers, etc. The application of the effect is very good, which is the industry for the use of titanium technology to carry out the transformation and the construction of three new 600,000 tons of annual output of the soda ash plant has played a model role.

For example: a soda ash plant distillation tower at the top of the ammonia condenser application of pure titanium pipe instead of cast iron pipe. Ammonia condenser is a soda ash production process, the distillation tower will steam out of the ammonia condensing equipment, it consists of two cast iron cooling box, each box diameter 2.5m, 1.2m high, the original box Φ63 × 6 × 2986mm cast iron tubes 214, a total of 428 of the two boxes. Both inside and outside of the pipe are anticorrosive with thermosetting phenolic varnish, and the medium outside of the pipe is NH3, CO2, H2O vapor at a temperature of about 95℃. Inside the pipe go NH4Cl mother liquor, and outside the pipe medium for heat exchange. Under these conditions, the cast iron pipe corrosion is serious, the use of a year that is part of the pipe corrosion perforation, 2 years has been corrosion damage is serious, stop using. In order to solve the problem of serious corrosion of cast iron pipe in the ammonia condenser, all cast iron pipes are replaced with TA2 titanium pipes, with specifications of Φ60×2×3010mm, and the titanium pipe ends are sealed with O-ring rubber rings between the pipe ends and the cast iron splash plates. This is China's soda ash industry, the first distillation tower cooling tubes using pure titanium tubes. Put into production and use for more than two years, has been pumping pipe for macro inspection, no corrosion phenomenon, is expected to service life of up to 20 years or more, can be extended by 10 times than cast iron pipe. As the titanium tube corrosion resistance, heat transfer efficiency to maintain good (cast iron pipe in 3 years during an overhaul, the heat transfer efficiency of the early good, poor mid-term, late on the failure), the tube NH4Cl mother liquor preheating heat recovery, improve the mother liquor into the distillation tower temperature, can save a lot of steam, the economic benefits are obvious.