Severe coking occurs on the outer wall of the tube bundle of the constant-pressure/constant-temperature crude oil heat exchanger in petrochemical industries
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The image below shows the tube bundle of the constant-pressure/constant-temperature heat exchanger for crude oil in the petrochemical industry; under operating conditions, the fluid flowing through the tubes is constant-pressure/constant-temperature oil, while the fluid flowing outside the tubes is crude oil； The operating temperature is 186 degrees in the tube side and 138 degrees in the shell side ； The pressure in the tube side is 0.94 MPa, and that in the shell side is 0.8 MPa. After being in use for over a year, this tube bundle suffered severe fouling on the shell side, which affected its normal operation.
Coking is mainly caused by the thermal cracking of heavy components in crude oil at high temperatures. The following solutions can be considered to address the issue: 1. **Adjust the operating temperature**: Reduce the operating temperature in the shell side to prevent excessive cracking of the oil at high temperatures. 2. **Increase the cleaning frequency of the tube bundle**: Regularly perform chemical or physical cleaning of the heat exchanger to remove carbon deposits. 3. **Improve the quality of crude oil**: Use crude oil with better stability to reduce the formation of coke. 4. **Optimize heat exchanger design**: This includes using materials that can withstand high temperatures and resist coking, or increasing the spacing between the tubes in the heat exchanger to improve fluid dynamics and reduce dead zones, which helps to minimize coking. Ensure that appropriate measures are taken to improve the efficiency and lifespan of the equipment. .