Application of Titanium materials in petrochemical industry

Titanium heat exchangers, condensers and related auxiliary equipment have been successfully used in petrochemical enterprises for more than 20 years. Titanium is the most commonly used industrial pure titanium (Gr2 is the most widely used), Ti-6Al-4V (when a certain strength is required) and Ti-0.8Ni - 0.3Mo (when there is a gap or in non-oxidizing media).

(1) In the crude oil refining with high sulfur and salt content, titanium equipment is more ideal. Titanium equipment has been successfully used in many processes such as atmospheric distillation unit, sewage treatment equipment, condenser of desulfurization separation tower and radiator of stripping tower for many years. China has also used cast titanium sea pump, titanium condenser in catalytic cracking fractionation, cryogenic separation of titanium condenser and porous titanium plate in this system, which have been in normal operation for more than 10 years.

(2) Chlorinated hydrocarbons are one of the largest varieties of petrochemical industry. Due to the chlorination reaction involved, stainless steel equipment has been unable to perform. Internationally, titanium has been used to manufacture dichloromethane rectification towers, trichloroethane heat exchangers, condensing towers and fractionating towers, trichloroethylene condensing towers, perchloroethylene heat exchangers and polychloride coil heaters. In the production of vinyl chloride in China, the tray support frame, nozzle and flange sealing surface of the cooling tower, waste water stripping tower and waste water storage tank are lined with Ti-0.2Pd, which has been used for nearly ten years without corrosion. Titanium pipes, joints and gas distributors have been made of titanium for many years.

(3) Phenol is an important raw material of petrochemical industry. It is a new process to obtain phenol and acetone from isopropylbenzene and isopropylbenzene peroxide by using propylene and benzene in oil refining gas as raw materials. Titanium equipment was used in the world more than a decade ago. In the old process, benzene sulfonated alkaline solution was used to produce phenol. China has adopted titanium neutralization reactor, titanium coil cooler and ion-titanium nitride agitator shaft sleeve, and the effect is very good.

(4) In the device of ethylene oxidation to acetaldehyde, acetaldehyde oxidation to acetic acid and propylene oxidation to synthesize acetone, in addition to the corrosion of raw materials and products, the main corrosion medium is the catalyst, stainless steel corrodes quickly in which only titanium has good corrosion resistance. As early as 1963, the United States successfully applied titanium in the production of ethylene oxidation to acetaldehyde. China's first ethylene oxidation to acetaldehyde plant has been put into use in 1976, and the titanium equipment has been running well so far. Internationally, the titanium lined reactor is up to 9.6m, the diameter is 3m, and there are 11 titanium equipment such as heat exchangers, catalyst regeneration towers, acetaldehyde solution coolers. In China after the 1980s, Shanghai and Jilin have built complete sets of equipment for ethylene oxidation to acetaldehyde, many of which equipment and valves are made of titanium, which has obvious advantages compared with stainless steel, and the use effect is very satisfactory. The final design of propylene oxidation to acetone, titanium equipment has 12 sets, a factory with an annual output of 30,000 tons of acetone, titanium equipment up to 40t.

(5) acetaldehyde oxidation to acetic acid is a general process in China, and titanium has been used as a high-boiling reboiler, a grade acetic acid tower reboiler and condensation cooler and other equipment. Titanium equipment is used in the international rectification tower, fractionation tower and distillation tower. Especially in the oxidation of low alkane to acetic acid by more by-products, formic acid content of 8%, extremely corrosive, at this time use titanium instead of stainless steel, the effect is very ideal.

(6) terephthalic acid is the raw material of synthetic polyester, which is obtained by p-xylene oxidation process in industry. Whether it is high temperature oxidation or low temperature oxidation, there is high temperature corrosion of acetic acid and bromide, in the medium with a temperature higher than 135 ° C, 316L stainless steel will pitting after dozens of hours. Therefore, the design specification stipulates that titanium must be used above 135 ° C. Beijing Petrochemical Complex introduced a full set of titanium equipment, including oxidation reactor, solvent dewatering tower, heater, condenser, reboiler and other 16 sets. Nanjing Yangzi Petrochemical Company introduced an annual output of 450,000 tons of terephthalic acid equipment, 56 sets of titanium equipment and a large number of titanium pipeline valves. The oxidation reactor introduced by Shanghai Petrochemical Complex is 32m high with an upper diameter of 4m and a lower diameter of 5.3m, with a volume of 505m and a weight of 175t. The effect of titanium is very good, and the prospect of popularization and application is bright.

(7) Urea is a high-quality fertilizer and a raw material for petrochemical industry. Since the first pure titanium urea synthesis tower was put into operation in 1963, there have been nearly 10,000 devices in operation around the world, and practice has shown that pure titanium synthesis tower has no obvious corrosion. The converted corrosion rate of 316L stainless steel is 4.1-4.5mm/a. Therefore, titanium has better economic benefits than stainless steel. In addition to titanium lined urea synthesizer, since the 1970s, China has used C02 stripper, heat exchanger, mixer and pump valve.