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Potential risks and anti-corrosion methods of graphite condensers
- 2019-12-16-

Graphite condenserThe potential risks are as follows:
1. Flammable ingredients
Mainly hydrocarbons such as acetylene. Acetylene is the most risky. The solubility in liquid oxygen is very low (5.6×10-6mg/L), and it is easy to separate in solid state and cause explosion.
2. Strong oxidizer
Liquid chlorine is a strong oxidant.
3. Clogging elements
Mainly carbon dioxide, moisture and nitrous oxide, especially nitrous oxide, are increasingly attracting attention. After they crystallize and separate, they block the main cold channel, which will cause the main cold "dry transpiration" and "dead end jubilation" to form hydrocarbons. Concentrate, accumulate and separate, triggering the main cold blasting.
4. Detonating elements
a. The mechanical impact of solid impurity particles detonates acetylene particles and other friction and liquid oxygen impact.
b. Static electricity, if carbon dioxide particles reach (200~300)×104ppm, static electricity can occur, and the voltage can reach 3kV.
c. Chemically sensitive substances (such as ozone and nitrogen oxides).
d. Pressure pulses caused by airflow impact, pressure impact, and cavitation phenomena, causing temperature rise and explosion.
Condenser to avoid corrosion
The material of the condenser is generally carbon steel, stainless steel and copper. When the tube sheet made of carbon steel is used as a cooler, the welded seam of the tube sheet and the tube often leaks and the leakage into the cooling water system will cause Form pollution of the environment and waste of materials.
When the condenser is manufactured, manual arc welding is generally used for the welding of the tube sheet and the tube. The shape of the weld has different degrees of defects, such as depression, pores, slag inclusion, etc., and the stress distribution of the weld is not uniform. When in use, the tube sheet part touches the industrial cooling water, and the impurities, salts, gases, and microorganisms in the industrial cooling water will cause corrosion to the tube sheet and the weld. The study showed that whether industrial water is fresh water or sea water, there will be various ions and dissolved oxygen, during which the concentration of chloride ions and oxygen changes, which play an important role in the corrosion shape of metals. In addition, the complexity of the metal structure will also affect the corrosion shape. Therefore, pitting corrosion and crevice corrosion are the main corrosion of welds between tube sheet and tube. From the outside, there are many corrosion products and sediments on the surface of the tube sheet, and bubbles of different sizes are distributed. When seawater is used as the medium, galvanic corrosion will also occur. Bimetal corrosion is also a common phenomenon of tube sheet corrosion.
In view of the anti-corrosion problem of condensers, Western countries often use polymer composite materials for maintenance, and high-end technical products are the most widely used. It has excellent adhesion function, temperature resistance and chemical corrosion resistance. It can be used safely without shrinking in a closed environment. In particular, it has outstanding bimetal corrosion resistance and erosion resistance, which fundamentally eliminates the corrosion of repaired parts. Leakage provides a long-term maintenance coating for the condenser.