What are the causes of large-scale leaks in VCM converters (hot water heat exchange)?

Inherent equipment issue: ① The tube wall does not meet the design requirements. (One of the reasons) ②, the equipment has reached the end of its useful life. Mechanical damage: ① During the catalyst turning process, the catalyst extraction is carried out by using a negative-pressure pipeline to draw out the catalyst from the tubes. In this operational step, the suction pipe failed to extend in promptly, causing the catalyst particles to move along the irregular wall surface of the pipe under negative pressure; over time, this can be one of the reasons for the thinning of the pipe walls in the lower parts of the converter. One of the reasons is issues with the quality of the converted hot water, such as ion-free water quality problems, high-temperature corrosion inhibitor problems, and other issues related to the quality of water reused (such as the seal water from alkali pumps). There are also problems related to cross-contamination between the steam generated for external use and the hot water used for heating at the heat exchange stations. Leaks in the reboilers of the distillation system can contaminate the converted hot water. The water quality of the hot water system was not replaced regularly. There is stagnant water below the hot water inlet of the converter, and over time this can cause the quality of the water in that area to deteriorate. There is a space between the upper edge of the flange on the hot water outlet pipe of the converter and the upper tube sheet; under the long-term effect of water vapor erosion, corrosion occurs. Raw gas moisture, mixed gas moisture, pressure swing adsorption product gas moisture, catalyst issues, problems with newly installed catalysts and moisture. The moisture issue related to the transfer of catalysts from the backstage to the foreground: Both of these catalysts must undergo drying and activation before they can be put into use. Question 1: If the catalyst is not completely dried under hot nitrogen, when the catalyst is activated, dry hydrogen chloride introduced will combine with the moisture present in the catalyst to form acid mist. This mist moves downward along the airflow and may cause wall flow on the walls of the converter tubes, leading to corrosion of those walls. Conversion for long-term and short-term parking involves pressure retention issues. For long-term parking: the inlet valve of the converter is closed, and the conversion system maintains its pressure independently. Short-term parking. To minimize inert gases (nitrogen) in the system as much as possible. Our current* standard practice is to use an air tank to reverse the flow of gas in order to maintain pressure in the conversion system and keep its pressure stable. This operational step does not rule out the possibility that moisture from the gas tank, after passing through the purification system, enters the converter. Under the adsorption action of the catalyst (activated carbon), it gets adsorbed on the catalyst particles. When driving, hydrogen chloride is first introduced; the hydrogen chloride that enters combines with the moisture adsorbed in the catalyst to form acid mist, which corrodes the converter. Convert one line to emergency shutdown; keep both distillation lines operational. The pressure in the conversion system where the vehicle is parked dropped suddenly; the process gas from the purification system flowed back into the conversion system after passing through water and alkali washes. This causes the catalyst adsorbent to become damp, and when hydrogen chloride is passed through it again, acid mist is generated, which corrodes the tubes in the converter. Catalyst-activated hydrogen chloride is humid; ① there is a slight leak in the activation preheater, resulting in high humidity in the catalyst-activated hydrogen chloride.

Check the pH value of the hot water system to see if it has become acidic.