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What are the hazards of impurities in water to plate heat exchangers
Source: Time: 2020-11-04 18:55:28 Hit:
No matter how good the quality of the plate heat exchanger equipment is, it will also be damaged by various impurities in the water. Let's explore the harm of impurities in the water to the heat exchanger.
The harm of impurities in water to plate heat exchangers
1、The harm of impurities dissolved in water in the state of ions or molecules(1) Calcium salt
The main components in water are Ca(HCO3)2, CaCl2, CaSO4, CaSiO3, etc. Calcium salt is the main component of plate heat exchanger fouling. Among them, CaSO4 is a hard, crystalline, dense scale with a loose structure and low adhesion. It is a soft sludge that separates from water and is easy to clean even on heated surfaces.
(2) Magnesium salt
The main components in water are Mg (HCO3), MgCl 2, MgSO4, etc. When magnesium is dissolved in water, it will decompose into Mg(OH)2, which is also sludge. When the pH of the water is less than 7, MgCl 2 and MgSO 4 will be hydrolyzed, which will cause acid corrosion of the metal wall.
(3) Sodium salt
NaCl is mainly composed of NaCl, Na2SO4, NaHCO3, etc. NaCl will not produce scale, but the presence of free oxygen in the water will accelerate the corrosion of the metal wall. Too high Na2SO4 content will produce salt in the accessories after the evaporator, which will affect safe operation; NaHCO3 in the water will decompose NaCO3 and Na. OH and CO2 will cause metal particles to be destroyed under the action of temperature and pressure.
2、Reduce the harm of oxygen
There are many reasons for plate heat exchanger corrosion. On the ordered list of atoms, iron is higher than hydrogen. In neutral water without oxygen, iron atoms on the metal surface of the system will lose electrons and enter divalent ions (Fe 2e to Fe2 ). The Fe2 ions and OH- ions in the water combine under the action of electrostatic force and establish a balance in the water.
When oxygen is present in the water, Fe(OH)2 is further oxidized to insoluble iron hydroxide.
When Fe(OH)3 precipitates, the iron ions around the anode are transferred to the aqueous solution to accelerate corrosion.
Water and oxygen are prerequisites for corrosion. The positive electrode is the corrosion part, and the negative electrode is the place where corrosion products accumulate. When the entire metal surface is corroded, the corrosion rate will not be very fast, so it is not harmful. When the corrosion is concentrated on certain parts of the metal surface, it is called localized corrosion. Local corrosion is fast and easy to wear. Pitting corrosion is a common local corrosion in heat exchangers, which is very harmful.
YOJO is a professional supplier of plate heat exchange equipment. It is inevitable that the heat exchange equipment will be damaged by impurities in the water, but as long as proper maintenance is done, if you want to know how to maintain it, click here>>. The heat exchange equipment produced by yojo The quality is trustworthy.
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