Why does the temperature at the bottom of the distillation tower rise suddenly?

Insufficient circulation of oil: When the oil circulating at the bottom of the tower stops and starts again, especially after the filter is cleaned, the oil there may develop a fairly stable stratification or sedimentation due to remaining stationary for an extended period of time. When the circulating oil is put back into use, if there is insufficient disturbance, the sediments at the bottom (such as coke powder) may not be adequately stirred, leading to localized heat accumulation. When the flow rate suddenly increases, the heat accumulated is released rapidly, causing the temperature at the bottom of the tower to rise sharply. Filter cleaning effectiveness: If the filter is not cleaned thoroughly and carbon residue or other impurities remain, these impurities can block pipes during circulation or affect the flow of the oil. Clogged or obstructed pipes can restrict the flow of oil, leading to localized temperature increases. Changes in the quality of circulating oil: After prolonged operation, the heavy components in the circulating oil may gradually increase, leading to a decline in the oil’s thermal stability and fluidity. When these lower-quality oils re-enter the bottom of the tower for circulation, they may accumulate more easily at the bottom of the tower and release heat. Changes in operating conditions: When restarting the bottom circulation, if operating conditions such as the heating intensity of the heater or the pressure in the distillation tower are not adjusted in a timely manner, it may also lead to an abnormally high bottom temperature.

Does the senior know if similar issues have occurred with other devices? Are there any technical measures that can improve things or prevent such issues from happening?

I’m flattered, but I didn’t expect this to happen； It is still necessary to conduct more analysis and compare the data from previous productions ； Enhance filter cleaning and maintenance: Ensure that the filters are thoroughly cleaned, with no residual impurities, in order to minimize the impact on the flow of circulating oil. Optimize circulating oil disturbance: When restarting the bottom-of-tower circulation, gradually increase the flow rate to avoid localized heat accumulation caused by a sudden increase in flow. At the same time, it is possible to consider increasing the degree of disturbance in the circulating oil, for example by changing the speed of the circulating oil pump or adjusting the pipeline layout. Monitoring and adjusting operating conditions: When restarting the bottom circulation, closely monitor changes in key operating conditions such as the heating intensity of the heater and the pressure in the distillation tower, and make timely adjustments to maintain a stable operating state. Regular inspection and cleaning of the tower bottom: The bottom of the distillation tower should be inspected and cleaned regularly to prevent the accumulation of coke powder and other impurities there, which could affect temperature control.

This sudden rise in temperature may be related to the sediment and impurities at the bottom of the tower. When the cyclic cleaning of the filter is stopped, some sediment or impurities may accumulate at the bottom of the tower. When the cycle is started again, if the flow rate is high, these deposits may be disturbed again, resulting in a sudden increase in the heat load and thus a rapid rise in temperature. A cycle of replacement over about a week helps to gradually remove these deposits, allowing the system to return to normal operation. It is recommended to adjust the flow rate gradually, avoiding sudden increases in flow, in order to reduce the impact of disturbed sediments. At the same time, regular cleaning of the bottom of the distillation tower may also help prevent such problems from occurring. .

Since the temperature sensor at the bottom of our distillation column is not too far from the outlet for bottom circulation, I generally assume that the sediment layer should not be very thick, and the temperature should be below 300°C. I don’t understand how the return of residue with a lower temperature to the bottom of the column can result in such a high temperature rise. I also asked my brother, and his device doesn’t have this issue, which is really puzzling.

What we do now is to gradually increase the flow rate after bringing the system into operation, but sometimes the temperature still rises suddenly, which has a significant impact on the heating furnace; the operators are very worried and find it extremely difficult to make the necessary adjustments.

There could be several reasons for this situation: 1. **Changes in heat transfer conditions within the tower**: When the circulation is stopped or started, especially when there are significant changes in flow rates, it may affect the heat transfer efficiency within the tower. If there is a large amount of residue at the bottom of the tower, or if the heat transfer area is limited, heat may not be transferred effectively during the heating process, resulting in localized temperature increases. 2. **Changes in operating conditions**: When restarting the cycle, rapid changes in flow rate can lead to unexpected variations in operating pressure or flow dynamics, which in turn may indirectly affect temperature stability. 3. **Equipment issues**: It may also be related to the calibration or performance of the temperature measurement equipment or other related control devices. For example, if the temperature sensor is not in the right position or there are issues with the device itself, it may lead to incorrect temperature readings. 4. **Chemical reaction factors**: There may be trace amounts of reactive substances at the bottom of the tower; when it is restarted and the flow rate is adjusted, these substances may start to react, releasing heat. Improvement measures may include: - **Optimizing the startup process**: gradually increasing the flow rate to avoid sudden temperature changes. - **Regular cleaning and inspection**: Ensure the cleanliness of the bottom part of the tower and the proper functioning of the equipment. - **Re-calibrate and check the sensors**: Ensure that all measuring devices are calibrated and functioning properly. - **System simulation and analysis**: Use process simulation software to simulate the system’s response under different operating conditions, in order to better understand the influencing factors. It is recommended to work with the equipment manufacturer or professional engineers to conduct a thorough analysis of the problem in order to find the best solution. .

High-boiling-point components reach their boiling point within their respective temperature ranges. Take a look at the endothermic and exothermic curves of the different fractions. Understanding this principle allows one to know the optimization strategies for aspects such as flow rate, temperature, and pressure.