Heat exchangers (also known as heat exchangers or heat exchange equipment) are devices used to transfer heat from a hot fluid to a cold fluid to meet defined process requirements and are an industrial application of convective heat transfer and heat conduction.
Heat transfer can be a difficult task when dealing with corrosive media such as acids, chlorinated compounds and vapourised fluids. Corrosion can lead to a loss of mechanical integrity and scaling. Scaling is the result of depositing unwanted material on a surface. This can alter the heat transfer coefficient of the surface and affect the performance of the heat exchanger.
1.Material corrosion
Corrosion of valves and equipment is a common problem for the chemical, refining, oil and gas related processing industries.
According to approximate defence statistics, the US military scraps more than 5% of its equipment each year due to metal corrosion, which also causes a significant increase in the cost of repairing and protecting weapons and equipment. According to the US Department of Defense, the US Naval Service loses an estimated US$7 billion annually due to corrosion, of which US$500 million is spent on repairing corroded Marine Corps ground vehicles.
2.The seriousness of corrosion
The Chinese Academy of Engineering's major consulting project Huan Baorong, Wang Jingquan and other academicians on industrial corrosion survey "our corrosion situation and control strategy research" survey results show that in 2014, China's losses due to corrosion reached 2.1 trillion yuan, accounting for about 3.34% of the GDP of the year.
According to a survey in the United States, the losses caused by corrosion can reach as much as 6% of the US GDP. On the same scale, globally, annual corrosion losses total more than US$4 trillion.
3.Advantages of tantalum plating technology
Tantalum is recognised as the most corrosion-resistant metal
Low temperature chemical vapour deposition (CVD for short)
Surface alloy prepared
Has the physical properties of tantalum metal
Effective in improving the mechanical properties of the substrate
Excellent deformation and bending capabilities
Unrivalled resistance to corrosion, high temperature and pressure
The best choice for harsh service conditions
4.Advantages of tantalum-plated heat exchangers
Performance of tantalum-plated products in different environments
Nickel-based alloys, zirconium and titanium thermowells are susceptible to stress corrosion cracking (SCC) and pitting, especially in hot acids. Tantalum, on the other hand, performs extremely well in hot acids.
Performance in corrosive media
Corrosion
Chemically resistant to SCC and pitting in many corrosive media and environments.
In high temperature acidic conditions
acids
Tantalum layers remain passivated and inert to corrosion under acidic conditions (including concentrated HCl and H2SO4) at high temperatures (>200°C).
In chlorine-containing environments
Chlorine
Excellent corrosion resistance to humid, dry chlorine atmospheres and other chlorinated environments.
Application environments for tantalum-plated heat exchangers
Chemical processing
Pickling chlorinated solvents, strong acids such as HCl, H2SO4, HNO3, hot corrosive waste liquids
Petroleum
Natural gas
Heating flue gases (CO2, H2S, SO2), ammonia treatment
Pharmaceuticals
Volatile oxidising compounds such as dichloromethane and methanol
Semi-conductors
Preparation of strong HCl etchant, processing of silicon deposition by-products
General industry
Hot volatile chlorides, corrosive salts, sulphide, methanation
5.Typical applications for tantalum-plated heat exchangers
Acid heat exchangers Reboilers Acid evaporators
Process equipment Condensers Regenerative heat transfer
Digester heating Waste water cooling Waste heat recovery
Process fluid heating and cooling
