Causes of CO2 backflow in the high-pressure loop and solutions? (CO2 stripping process)

The disappearance of the seal on the liquid outlet pipe of the synthesis tower during material feeding, or failure to address promptly the evacuation of the liquid level in the synthesis tower during production, can both lead to CO2 backflow. Reason: (1) A liquid seal was not promptly applied to the liquid outlet pipe of the synthesis tower during the feeding process, or the flow rate was insufficient. (2) It is difficult to evaluate 902-J; the amount of water added is not sufficient to create a liquid seal. (3) The outlet pipe of the synthesis tower is connected too late or the connection pipe is blocked. (4) A malfunction in the instrument of the liquid outlet valve of the synthesis tower causes it to stay fully open, or there is excessive internal leakage preventing the formation of a liquid seal. (5) During normal production, improper adjustment of HV201 or a malfunctioning level gauge led to evacuation, and the liquid outlet valve of the synthesis tower was not closed in time. Phenomenon: (1) PR204 rises sharply, steam production from 202-C drops significantly, TR002/8 drops sharply, while TR002/1 and 5 increase, and R002/2, 3, and 4 also decrease. (2) During the material feeding process, \"backflow\" occurs; the liquid level is not displayed in the synthesis tower for an extended period, and the pressure rises rapidly. (3) During the production process, CO2 \"backflow\" occurred, causing a sudden drop in the load of 201-C, while PIC904 and PIC901 saw a sharp increase, and FR902 and FR901 experienced a sharp decline. Treatment: (1) During the material feeding process, it is necessary to maintain a liquid seal in the liquid outlet pipe of the synthesis tower at all times; pay attention to changes in TR002/5, and add water to the outlet pipe or establish a connection as needed. (2) In the event of CO2 backflow during normal production, the liquid outlet valve of the synthesis tower should be closed immediately, HV901 should be opened to reduce the pressure at PIC904, HV203 should be used to maintain system pressure, water should be filled into the liquid outlet pipe of the synthesis tower, and discharge can proceed only after the level in LR201 returns to normal. If a liquid seal cannot be established, CO2 can be used to export it and then a liquid seal can be filled into the outlet pipe of the synthesis tower. (3) During the processing, it is necessary to adjust the operating conditions of the unit in a timely manner to prevent sudden increases in vibration.

Generally speaking, under normal production conditions, the likelihood of CO2 backflow is not high; as long as proper control is maintained to keep the liquid level in the synthesis tower, there will be no problems. If CO2 backflow occurs during production, in addition to turning on the high-pressure flushing pump, the self-liquid seal can also be activated.

It generally does not occur during normal production, unless there is a malfunction in the bottom liquid valve of the synthesis tower. And it can only happen if the operator fails to notice. When driving the original machine, if the control over the lower liquid valve is not proper, opening it too tightly can also cause backflow. If this occurs, close the liquid discharge valve, and the on-site operator should start the high-pressure pump to add liquid; if the high-pressure pump will not start. Open the discharge valve of the high-pressure ammonium hydroxide condenser to establish a liquid seal.

To be honest, here in the past, after short or long shutdowns, it was common for the liquid seal in the synthesis tower to be breached. During the maintenance carried out after those long shutdowns, it was found that the control valves on the liquid outlet pipeline of our synthesis tower were leaking severely; in the most serious cases, even when a water pump was used to add water in order to maintain the liquid seal, as soon as feeding started, the liquid seal would inevitably be broken. Later, the self-liquid seal method had to be adopted. In this approach, there is a connection between the liquid outlet from the high-pressure ammonia addition condenser and the liquid outlet line of the synthesis tower; this allows for effective liquid sealing as long as there is a certain level of liquid in both the synthesis tower and the high-pressure ammonia addition condenser. We have found this method to be highly reliable in our tests. As for the phenomena that occur after the liquid seal is punctured, what was mentioned above has covered it comprehensively. However, when adding materials, it is essential to pay attention to the speed at which they are added; in other words, the material feeding valve must be opened slowly. This post was last edited by lxq700918 on 2009-2-12 21:21.]