Do You Know Why the Heat Exchanger Tube Body Is Leaking?

Heat exchangers, as common chemical equipment, also have many problems in the process of use. Take the shell and tube heat exchanger as an example, the leakage of the tube itself is a very serious problem. In the following, we will talk about the reasons why leaks occur and hopefully help with solutions later on.

Here is the content list:

• Scouring Erosion

• Tube vibration

• Erosion at the inlet end of the tube feedwater

• Corrosion

Scouring Erosion

One cause is when the steam flow rate is high and the vapor stream contains large droplets of water, the outer wall of the tube is scoured by the two-phase flow of steam and water, thinning, perforation occurs or by the pressure of the feed water and drum break. Due to the anti-shock plate material and fixed in an unreasonable manner. Broken or fallen off in operation, the loss of anti-scouring protection. The anti-scouring plate area is not large enough, and water droplets with high-speed airflow movement hit the anti-scouring plate outside the tube bundle. These are the causes of tube leakage in shell and tube heat exchangers.

Tube vibration

Feed water temperature is too low or unit overload, etc., through the shell and tube heat exchanger between the steam flow and flow rate more than the design value, with a certain elasticity of the tube bundle in the shell side of the fluid disturbance force will produce vibration. When the frequency of the excitation force coincides with the natural vibration frequency of the tube bundle or its multiples, will cause the tube bundle resonance, so that the amplitude greatly increased. This leads to repeated forces on the connection between the tube and the tube plate causing damage to the tube bundle. This is also a major cause of leakage in shell and tube heat exchangers.

Erosion at the inlet end of the tube feedwater

Erosion damage at the inlet end of the tube occurs only in carbon steel heat exchangers, which is a damaging process of erosion and corrosion acting together. The mechanism is that the oxidation film formed on the surface of the tube wall metal is destroyed by the high turbulence of the feed water and carried away, and the metal material is continuously lost. This eventually leads to the breakage of the tube. In the case of low solution PH and high oxygen content, shell and tube heat exchangers are more prone to erosion.

Corrosion

When the low-pressure heat exchanger tube for copper low plus copper tubes are often forced to replace. pH 8.5 ~ 8.8, copper corrosion rate is the lowest. And carbon steel requires a pH value of not less than 9.5. boiler feed water pH value is too high, resulting in the corrosion of copper tubes. The main factors affecting the corrosion of carbon steel tube bundles are oxygen content and feedwater pH value.

With the widespread use of heat exchangers, ordinary people are increasingly exposed to these high-end devices. But when problems occur, it is important that we are able to identify the causes to make treatment. The above describes several causes of tube leakage in shell and tube heat exchangers, and I hope it can be helpful to you.