Practical application and requirements of heat exchanger

The structure of heat exchanger and external iron box is serious
1. The structure of heat exchanger group and external iron box was seriously deformed.
2. The damage of heat exchanger group and pipeline causes fire or cannot be dealt with urgently.
3. In the process of startup and shutdown, abnormal phenomena occur in the system, endangering the safety of the equipment.
4. Other emergencies endangering personal safety and heat exchanger unit.
In the process of practical application of heat exchanger, the tube bundle of heat exchanger is easily affected by medium, or material problems, such as stress corrosion, intergranular corrosion, pitting corrosion and fatigue corrosion. In view of this situation, it should be checked by means of pressure test, so as to understand the leakage condition and specific location of the heat exchanger. If there is corrosion perforation in the inner tubes of the heat exchanger, it is easy to cause serious leakage problems, which will have a negative impact on the production of the device itself. If this type of failure occurs in the heat exchanger, the cost of replacing the tube core is relatively high, so it is necessary to extract the original tube core and complete the installation of the new tube core.
The temperature of the medium to be cooled, the velocity of the water side of the heat exchanger, the outlet temperature of the circulating water, the heat flux, the annual fouling resistance and the annual corrosion rate are closely related to the treatment of circulating water. The general provisions are as follows:
(1) Cooling water side flow rate of heat exchanger: tube side should not be lower than 0. 9 m / s, the shell side should not be less than 0. 3 m/s。
(2) Outlet temperature of circulating water: not higher than 50 ℃ (this limit is not allowed under special circumstances).
(3) Heat flux of heat exchanger: no more than 58. 2 kW/m2。
(4) Fouling thermal resistance value: it should be determined according to the nature of the enterprise, production characteristics and the requirements of heat exchange equipment.
(5) The annual corrosion rate of heat exchanger: ① ordinary carbon steel should be less than 0. 125mm/a。 ② Steel, copper alloy and stainless steel should be less than 0. 005mm/a。
(6) The total number of heterotrophic bacteria should be less than 5 × 10 5 / ml.
(7) Sludge amount of heat exchanger: 180 mesh biological filter method should be less than 4 ml / m3 water.
(8) Process medium leakage of heat exchanger: the process medium of heat exchanger often leaks. If the leakage contains ammonia, carbon dioxide, oil and other substances, the quality of circulating water will deteriorate and bacteria and algae will breed.