Soda ash is one of the most basic chemical raw materials, and it is directly related to the development of the national economy. During the production of soda ash, the gaseous medium is mostly NH3 and CO2, and the liquid medium is mostly NaCl, NH4Cl, NH4HCO3 and Cl-concentrated solutions. Carbonized tower tubes and hot mother liquid coolers using carbon steel and cast iron for carbonation , The main equipment such as cooler, crystallization external cooler, etc., are not resistant to corrosion, serious corrosion leakage, service life is not more than three years. From 1975 to 1977, Tianjin Alkali Plant and Dalian Chemical Industry Company established titanium demonstration projects, carbonization tower cooling tube 63 × 2mm, titanium plate heat exchanger, titanium external cooler, titanium pump, CO2 turbine compressor rotor , Ti-6Al-4V alloy impeller and other applications have a very good effect, which has played a role in the industry for the transformation of titanium technology and the construction of three new 600,000 tons of soda ash plant.
For example, an ammonia condenser at the top of a distillation tower of a soda ash plant should use pure titanium tubes instead of cast iron tubes. The ammonia condenser is a device for condensing the ammonia gas distilled from the distillation tower during the production of soda ash. It consists of two cast iron cooling boxes, each with a diameter of 2.5m and a height of 1.2m. The original box has Φ63 × 6 214 × 2986mm cast iron tubes, 428 in two boxes. Both the inside and outside of the pipe are anti-corrosion with thermosetting phenolic varnish. The medium outside the pipe is NH3, CO2, H2O vapor, and the temperature is about 95 ℃. Take the NH4Cl mother liquor inside the tube to exchange heat with the medium outside the tube. Under this condition, the cast iron pipe is severely corroded, and some pipes are corroded and perforated after one year of use. After 2 years, the corrosion has been severely damaged and the use is stopped. 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, the specifications were Φ60 × 2 × 3010mm, and the titanium pipe ends were sealed with O-type rubber rings. This is the first titanium cooling tower in China’s soda industry. It has been put into production for more than two years. The tube has been drawn for macro inspection, and no corrosion has been found. The expected service life can reach more than 20 years, which can be 10 times longer than that of cast iron pipes. Due to the corrosion resistance of the titanium tube, the heat transfer efficiency remains good (the cast iron tube has a good heat transfer efficiency in the early stage, poor in the middle stage, and will fail in the later stage during a major overhaul of 3 years). The temperature can save a lot of steam, and the economic benefit is obvious.