Failure Analysis During the Operation of the Heat Exchanger

The heat exchanger is a process equipment that transfers the heat between different temperature media by heat conduction from high-temperature objects to low-temperature objects when the objects reach the required temperature for production. At present, heat exchangers are not only used in large chemical raw material manufacturers but also have entered the daily use of thousands of households. Below we introduce two common heat exchanger failures.

Here is the content list:

• Liquid cascade

• Stress corrosion

• Solution

Liquid cascade

The main characteristic of the liquid cascade is that the medium on the higher-pressure side cascades into the medium on the lower-pressure side. Abnormalities in pressure and temperature can occur in the system. The causes are varied. Cracking or perforation due to plate corrosion caused by improper plate selection. Operating conditions do not meet design requirements. Stress corrosion is caused by residual stress after cold stamping and undersized clamping during assembly. Slight leakage at the leakage groove of the plate, causing harmful substances in the medium to corrode the plate and form a string of liquid. These are the reasons for the string liquid phenomenon in the plate heat exchanger.

Stress corrosion

Corrosion of the plate heat exchanger mainly refers to the corrosion of the plate. Although most of the plate is made of stainless steel sheet pressed, and stainless steel has very good corrosion resistance, in some special conditions, the destruction of the passivated film so that the stainless steel plate uniform or localized corrosion. Plate heat exchanger plate in some special conditions, the destruction of the passivation film so that the stainless steel plate uniform or localized corrosion. In the combined effect of tensile stress and corrosive medium metal powder local corrosion damage, damage form is crack, crack until fracture. Chloride ion is a major factor causing stress corrosion. The chloride ion radius is small, the penetrating force is very strong, it is easy to penetrate the protective film within the very small pores, damage to the local passivation film and into the crack tip to generate hydrochloric acid, resulting in the white accelerated catalytic accelerated corrosion process.

Solution

The series of liquid treatment methods are relatively simple. In the field with the light transmission method to find the plate cracks, replace the cracked or perforated plate. Adjust the operating parameters to bring them to the design conditions. Heat exchanger maintenance and assembly of clamping size should meet the requirements, strictly in accordance with the instructions for clamping size operation. Plate materials are reasonably matched. These methods can solve most of the string liquid problems.

The solution to stress corrosion is also relatively simple. The occurrence of heat exchanger corrosion can be reduced by reducing the concentration of chloride ions in the medium. The occurrence of plate heat exchanger stress corrosion can be prevented by the improvement of the processing process.

The above introduction analyzes the most common problems in the operation of the two versions of heat exchangers and gives the corresponding treatment methods. If the plate heat exchanger you are using also has the corresponding problems, I hope it can give you some help!