Why do we need to repair and maintain the heat exchanger?
In oil refining and chemical production, some of the media passing through the heat exchanger contain coke and other deposits, and some are corrosive. Therefore, after using the heat exchanger for a period of time, it will accumulate scale and form rust in the overflow parts such as heat exchange tubes and shells; this reduces the heat transfer efficiency on the one hand; on the other hand it reduces the flow cross section of the tube and increases the flow resistance, even causing blockage. In addition, dielectric corrosion will also make the tube bundle, shell and other parts damaged. The vibration and uneven heating of the equipment during long-term operation may cause leakage at the pipe expansion joints and other connections. These will affect the normal operation of the heat exchanger, and even force the device to shut down. Therefore, the daily maintenance of the heat exchanger must be strengthened. Regular inspections and repairs must be carried out to ensure the normal production.
What is the daily inspection of heat exchangers?
The inspection includes: whether there is leakage of the equipment; whether the heat insulation or cold insulation is good; whether the equipment without heat insulation and cold insulation is obviously deformed, and whether the foundation or supporting hanger is good; whether the equipment has ultra-high pressure. For heat exchangers with safety accessories on site, check whether the safety accessories are good; use a listening stick to determine whether there is abnormal sound in the device, and confirm whether there is mutual friction and vibration in the heat exchanger.
What are the preparations before overhauling the heat exchanger?
(1) Grasp the operation and prepare necessary drawings and documents.
(2) Prepare necessary maintaining tools and test tires, fixtures, etc.
(3) Replace and clean up the internal medium, which should meet the safety inspection conditions.
What does heat exchangers overhaul include?
1. Macroscopically check the casing, tube bundle and components for corrosion, cracks, deformation, etc. If necessary, surface inspection and eddy current inspection shall be adopted randomly.
2. Check if the anti-corrosion layer is aging or falling off.
3. Check for lining corrosion, bulging, wrinkles and cracks.
4. Check the sealing surface and gasket.
5. Check the fastener for damage. High-pressure bolts and nuts should be cleaned and inspected one by one. If necessary, non-destructive testing should be carried out.
6. Check the foundation for sinking, tilting, damage, cracks, and other anchor bolts and horns for looseness and damage.