Steam reboiler water hammer
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This post was last edited by cjh950218 on 2024-7-16 at 19:00. We have a distillation tower for C4 separation; due to process modifications, the load on the entire tower is currently low. The steam consumption of the tubular reboiler located at the bottom of the tower is around 2–3 tons per hour. A drain valve is also installed behind the reboiler. However, since the plant started operating again, water hammer has persisted in this heat exchanger. We tried opening the manual valves before and after the on-site drain valve, but that didn’t help – the water hammer continued to occur. Currently, the only way to reduce the severity of water hammer is by draining condensate through the drain port on the reboiler itself. Before the renovation, the steam consumption of the reboiler in this distillation tower was around 10 t/h, and no water hammer phenomenon occurred. Could everyone please help analyze what might be the cause and whether there are any solutions? Additionally, the operating temperature at the bottom of this tower is 55–65°C; the steam used is at 0.6 MPa and 180°C.
The water hammer phenomenon is usually caused by abnormal flow of steam and condensate. After the modification, the steam consumption of the reboiler in the tower bottom decreases, which may lead to uneven steam distribution or poor drainage of condensate water. You can try the following methods to solve it: 1. Check whether the steam trap is working properly, ensuring there is no blockage or damage. 2. Adjust the hydrophobic system, which may require adding more hydrophobic points or optimizing the hydrophobic pathways. 3. Check the reboiler’s vent system to ensure it is unobstructed. 4. Consider adding an automatic control system to adjust steam and drain automatically based on the load. The methods mentioned above can help improve the situation related to water hammer; it is recommended to start with simple procedures and gradually work through the issues. .
The process of the distillation tower must meet the original designed production capacity; adjustments within a certain range are acceptable. If this range is exceeded, problems will occur. It is recommended to start by checking the original design parameters to determine whether the modification is reasonable; this can serve as a reference.
Water hammer……Following the Soviet design approach, if it’s not possible to address the root cause, then deal with the practical aspects by connecting a buffer tank or attaching one separately……
“\"Open the on-site drain valve and the upstream and downstream manual valves\" —— Should the upstream and downstream valves be fully open? “The water hammer can only be reduced by draining the condensate through the drain port on the reboiler itself” – this shows that the drainage of the condensate is not smooth
This post was last edited by Watt Energy Saving on 2024-12-2 at 11:45. Proper discharge of steam condensate is only possible when the pressure inside the heat exchanger is higher than the outlet pressure. Therefore, the ideal operating condition is a positive pressure difference at the inlet and outlet of the heat exchanger. However, changes in the process or overly large equipment design often result in an oversized selection of steam heat exchangers. According to the heat transfer calculation formula Q=KA Δt, when the heat transfer area far exceeds the actual requirement, it is necessary to reduce the heat transfer temperature difference Δt; with the average temperature of the product remaining unchanged, this means lowering the temperature of the steam. Lowering the steam temperature inevitably results in a decrease in the steam pressure downstream of the temperature control valve by ΔP, preventing it from overcoming the backpressure of the recovery system. When the steam temperature is below 100°C, a vacuum can even form inside the heat exchanger – and this is the temperature required for many processes. Fluctuations in the pressure difference between the inlet and outlet of the steam heat exchanger, or even a negative pressure difference, will hinder effective drainage. In extreme cases, the heat exchanger loses flow, preventing the condensate from being drained and causing water to accumulate within the equipment. Choosing a steam heat exchanger that is too large is a disaster for the process and damages the heater, as heat cannot be transferred; meanwhile, the accumulation of condensate water causes water hammer, which erodes the heat exchanger.