Tubular heat exchanger tube bundle failure and flange leakage

Tubular heat exchanger tube bundle failure and flange leakage

1. Tube bundle failure

　　 1. Corrosion and abrasion of the tube bundle cause tube bundle leakage or scale in the tube bundle causes blockage and malfunction

　　The cooling water contains metal ions such as iron, calcium, magnesium and other metal ions, anions and organics. Active ions will increase the corrosiveness of the cooling water. The presence of metal ions causes the depolarization reaction of hydrogen or oxygen, which leads to tube bundle corrosion. At the same time, because the cooling water contains Ca2+ and Mg2+ ions, it is easy to scale at high temperatures for a long time and block the tube bundle.

　　 In order to improve the heat transfer effect and prevent corrosion or blockage of the tube bundle, the following methods have been adopted:

　　 (1) Add scale inhibitor to the cooling water and clean it regularly.

　　For example, the cooling water of the gas cooler adopts an ion electrostatic processor or adds a scale and corrosion inhibitor and a bactericidal algicide to remove dirt and reduce the hardness of the cooling water, thereby reducing the degree of scaling of the tube bundle.

　　 (2) Keep the fluid flow rate in the tube stable.

　　 If the flow rate increases, the thermal conductivity will increase, but the wear will increase accordingly. Minsheng Coal Chemical has carried out a frequency conversion transformation on the underground water pump to stabilize the pressure of the underground water pipe network, improve the heat exchange effect of the heat exchanger and reduce the corrosion of the tube bundle.

　　 (3) Use corrosion-resistant materials (stainless steel, copper) or increase the thickness of the tube bundle.

　　 (4) When the end of the tube is worn, a protective tube bundle such as synthetic resin can be inserted into the inlet within a length of 200mm.

　　2. Failure caused by vibration

　　 The causes of vibration include: vibration of the tube bundle caused by the vibration of the pump and compressor; pulsation generated by rotating machinery; the impact of the high-speed fluid (high pressure water, steam, etc.) flowing into the tube bundle on the tube bundle.

　　 The following methods are often used to reduce the vibration of the tube bundle:

　　 (1) Try to reduce the number of opening and stopping.

　　 (2) Install an adjustment groove at the fluid inlet to reduce the vibration of the tube bundle.

　　 (3) Reduce the spacing of the baffles to reduce the amplitude of the tube bundle.

　　(4) Minimize the aperture of the tube bundle through the baffle.

　　 2. Flange leakage

　　 The leakage of the flange is caused by the temperature rise, the tightening bolts are heated and stretched, and there is a gap in the tightening part. Therefore, after the heat exchanger is put into use, the flange bolts need to be re-tightened. The fluid in the heat exchanger is mostly toxic, high-pressure, and high-temperature substances. Once it leaks, it is likely to cause poisoning and fire accidents. Special attention should be paid to the following points in daily work:

　　 (1) Minimize the number of gaskets used and use metal gaskets.

　　 (2) The method of tightening the gasket with internal pressure.

　　 (3) The easy-to-fasten operation method is adopted.