Applications of titanium alloys in the petroleum industry
Titanium heat exchangers, condensers and related auxiliary equipment have been successfully used in petrochemical companies for more than 20 years. Among titanium materials, the most commonly used industrial pure titanium (TA2 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 no oxidation medium).
(1) In the refining of high-sulfur and high-salt crude oil, titanium equipment is ideal. Abroad, titanium equipment has been successfully used in many processes such as atmospheric distillation units, sewage treatment equipment, desulfurization separation tower condensers, and stripping tower radiators. Our country has also used cast titanium seawater pumps, titanium condensers for catalytic cracking and fractionation, cryogenic separation titanium condensers and porous titanium plates in this system, which has been running for more than ten years without problems.
(2) Chlorinated hydrocarbons are one of the largest varieties of petrochemical products. Due to the chlorination reactions involved, stainless steel equipment is no longer adequate. Titanium materials have been used abroad to manufacture methylene chloride distillation towers, trichloroethane heat exchangers, condensation towers and fractionation towers, trichlorethylene condensation towers, perchlorethylene heat exchangers and polychlorethylene coil heaters. In my country's vinyl chloride production, the tray supports, pipes, and flange sealing surfaces of cooling towers, wastewater stripping towers, and wastewater storage tanks are all lined with Ti-0.2Pd and have been used for nearly ten years without corrosion. Titanium pipes, fittings and gas distributors have been manufactured from titanium for many years.
(3) Phenol is an important raw material in the petrochemical industry. It uses propylene and benzene in oil refining gas as raw materials, and produces phenol and acetone from cumene and cumene peroxide. This is a new process. Titanium equipment has been used abroad more than ten years ago, but this process is still in the development stage in my country. The old process uses benzene sulfonation alkali solution to produce phenol. Our country has adopted titanium neutralization reactors, titanium coil coolers and ion titanium nitride stirring jackets, with very good results.
(4) In addition to raw materials and products, titanium heat exchangers, condensers and related auxiliary equipment have been successfully used in petrochemical companies in the oxidation of ethylene to acetaldehyde, the oxidation of acetaldehyde to acetic acid, and the oxidation of propylene to acetone. More than 20 years ago. Among titanium materials, the most commonly used industrial pure titanium (TA2 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 no oxidation medium).
(5) Acetaldehyde oxidation to acetic acid is a common process in my country. Titanium materials are now used as high boiling point reboilers, primary acetic acid tower reboilers, condensation coolers and other equipment. Foreign titanium equipment is mostly used in distillation towers, fractionating towers, and distillation towers. Especially when lower alkanes are oxidized to generate acetic acid, there are many by-products, and the formic acid content reaches 8%, which is extremely corrosive. In this case, using titanium alloy instead of stainless steel will have a very ideal effect.
(6) Terephthalic acid is a raw material for the synthesis of polyester and is industrially produced by the oxidation of paraxylene. Regardless of high-temperature oxidation or low-temperature oxidation, there is high-temperature corrosion caused by acetic acid and bromide. In media with a temperature higher than 135°C, pitting corrosion will occur in 316L stainless steel after dozens of hours. Therefore, design specifications stipulate that titanium materials must be used above 135°C. The use effect of titanium materials is very good, and the prospects for promotion and application are very good.
(7) Urea is a high-quality chemical fertilizer and a raw material for the petrochemical industry. Since the first titanium-lined urea synthesis tower was put into operation in 1963, there are currently nearly 10,000 units of this equipment in operation around the world. Practice has shown that there is no obvious corrosion in the titanium-lined urea synthesis tower. 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 synthesis towers, CO2 strippers, heat exchangers, mixers, pump valves, etc. have been used in our country since the 1970s. In addition to having certain corrosion properties, the main corrosion medium is the catalyst, in which stainless steel corrodes quickly, and only titanium has good corrosion resistance. As early as 1963, the United States had successfully applied titanium to the ethylene oxidation method to produce acetaldehyde. my country's first ethylene oxidation to acetaldehyde unit was put into use in 1976, and the titanium unit is operating well to this day. The foreign titanium-lined reactor is 9.6m high, 3m in diameter, and has 11 titanium equipment such as heat exchangers, catalyst regeneration towers, and acetaldehyde solution coolers. After the 1980s in my country, Shanghai and Jilin introduced complete sets of equipment for ethylene oxidation to acetaldehyde from abroad. Many equipment, pumps, and valves are made of titanium, which has obvious advantages over stainless steel and has very ideal results. The final design of propylene oxidation to acetone includes 12 sets of titanium equipment. A factory with an annual output of 30,000 tons of acetone has 40 tons of titanium equipment.
