Titanium alloy has excellent corrosion resistance and mechanical properties, which is widely used in many departments. In particular, the application of chemical industry, with titanium can replace the stainless steel as corrosion resistant material, which is to extend the service life of the equipment, reduce costs, prevent pollution and improve productivity and so on has a very important significance.
In recent years, the scope of titanium used in chemical industry in China has been expanding, and the amount of titanium has been increased year by year. Titanium has become one of the main anti-corrosion materials in chemical equipment. Titanium, as a kind of corrosion resistant structural material used in chemical plant, has become an ideal material in chemical engineering equipment.
Chlor alkali industry
Chlor alkali industry is an important basic raw material industry, the production and development of a great impact on the national economy. This is because the corrosion resistance of titanium to chloride ion is better than that of stainless steel and other non-ferrous metals. At present in the chlor alkali industry is widely used to manufacture titanium metal anode electrolyzer and ion-exchange membrane electrolyzer, wet chlorine cooler, refined brine preheater, the dechlorination of chlorine gas cooling tower, washing tower etc.. The main components of these devices in the past using non-metallic materials (such as graphite, PVC etc.), because the process performance of mechanical properties, the thermal stability of metallic materials and processing is not ideal, resulting in heavy equipment, high energy consumption, short service life, and affect the quality of products and environmental pollution. Therefore, our country since 70s, began to use the metal anode electrode and ion membrane electric tank instead of graphite electrode, with titanium wet chlorine cooler instead of graphite cooler, have achieved good results.
For example: the application of titanium wet chlorine cooler. The production of caustic soda is to produce a large number of high temperature wet chlorine, the temperature is generally 75~95 degrees Celsius, need to be cooled and dry to use. In our country, the production of chlorine by electrolysis is not reasonable or the corrosion of cooling equipment affects the output and quality of chlorine gas, and the environment is seriously polluted. High temperature wet chlorine corrosion of titanium cooler into production, change the manufacture of chlor alkali industry in the production outlook. Titanium in high temperature wet chlorine environment is very resistant to corrosion, chlorine titanium at room temperature in the corrosion rate of 0.000565mm/a at 80 DEG C; the chlorine water, the corrosion rate of titanium is 0.00431mm/a; containing 95% wet chlorine, the corrosion rate of titanium at room temperature for 0.00096mm/a. Many of the commonly used chlor alkali titanium wet chlorine gas cooler, some of which have been used for nearly 20 years, is still intact.
Soda ash is one of the most basic chemical raw materials, it is directly related to the development of the national economy. In the process of producing sodium carbonate, gas medium is NH3 and CO2, liquid medium for the solution of NaCl, NH4Cl, NH4HCO3 and Cl- with high concentration, the use of steel and cast iron material for carbonation carbonation tower tubular cooler, cooler, heat, liquid crystal outer cooler main equipment, no corrosion, corrosion serious leakage, the service life of not more than three years. 1975-1977, Tianjin soda plant and Dalian chemical industry construction company of titanium application demonstration work, the application effect of carbonation tower cooling tube 63 x 2mm, titanium plate, titanium heat exchanger external cooler, titanium pump, CO2 turbo compressor rotor, Ti-6Al-4V alloy impeller is very good, this is the industry with titanium technology the transformation and new three with an annual output of 600 thousand tons of soda ash plant plays a role model.
For example, instead of a cast iron pipe top soda plant distillation tower of ammonia condenser application of pure titanium tube. Ammonia condenser is in the process of producing sodium carbonate, the ammonia distillation tower distilled condensation equipment, which is composed of two cast iron cooling box, each box diameter 2.5m, high 1.2m, the original is Phi 63 * 6 * 2986mm cast iron tubular 214, two boxes of 428 root. Both inside and outside of the tube are used thermosetting phenolic varnish preservation, the outside media for NH3, CO2, H2O vapor, temperature of 95 degrees celsius. Tube NH4Cl mother liquor, heat exchanger and pipe medium. In this condition, the corrosion of cast iron pipe is serious, the use of a year that there is a part of the pipe corrosion perforation, 2 years of corrosion damage is serious, stop using. In order to solve the ammonia condenser in the serious corrosion of cast iron pipe, cast iron pipe will replace all TA2 titanium tube, specifications for phi 60 * 2 * 3010mm, titanium pipe end and cast iron flower plate using O type rubber sealing ring. This is China's first industrial Soda Cooling tubular distillation tower is made of pure titanium tube. Put into operation for more than two years, has been pumping tube for macro inspection, no corrosion phenomenon is expected to use life of up to 20 years, 10 times longer than the cast iron pipe. Because the titanium tube corrosion resistance, good heat transfer efficiency (cast iron pipe during a 3 year overhaul of the heat transfer efficiency of early, middle, late failure), NH4Cl tube preheating heat recovery to improve liquor, liquor into the distillation temperature, can save a lot of steam, obvious economic benefit.