Chain reaction of frozen vinyl chloride distillation tail gas condenser

If the brine opening of the total condenser reaches 100% in a short period of time, it indicates a problem. Either the purity of the synthesized crude VCM changes greatly in an instant (that is, the instantaneous increase in non-cooling gases, such as hydrogen, acetylene, nitrogen and other non-cooling gases) or the amount of VCM gasified in the high-boiling material gasification tank is too large (can be judged by whether the height of the gas cabinet rises sharply, provided that the number of running compressors is certain, that is, the opening pressure is not increased when starting, or the gas cabinet is refluxed before high-boiling materials are discharged, and the height of the gas cabinet is not increased after the high-boiling gas is discharged) or the refrigerant temperature rises. There is still little data. "What was the opening of the total condenser brine to 100%" before? The opening of the hot water valves of the high and low boiling towers before and after the accident; the liquid level; the opening of the feed valve of the high boiling tower; the opening of the tail automatic control valve: the opening of the -35 degree brine automatic control valve; What is the combined flow rate of the pressure at the top and bottom of the tower and the pressure difference? "The temperature drop of the tail gas condenser" refers to the gas phase outlet temperature of the tail gas condenser or the return water temperature of -35 degrees brine? The liquid level measurement points of the high and low boiling towers are respectively located at the positions of the heating kettle (the flower plates of the upper and lower heads). Nearby or the bottom pressure measuring point is in the middle of the tube)? Is the low-boiling tower operating at overload? Is the feed to the low-boiling tower a pressure difference feed or a pump feed? Is there a flow meter? If there is an accident, what is the flow rate before and after? What is the activated carbon adsorption of the tail gas? PSA? Membrane adsorption? Evacuation? Your company's equipment pipeline configuration and other operating data are unknown. I currently believe that the cause of the accident is: when the accident occurred, the amount of steam rising from the bottom of the low-boiling tower was large and the feed liquid VCM could not come down (it may also be due to tower blockage, but it became normal later and can be ruled out, or due to overloading and the full tower. At this time, most of the low-boiling tower is liquid VC M) goes to the tail condenser and vaporizes here, causing "the tail gas condenser discharge temperature and the tail gas condenser temperature to reduce the boiling tower top pressure and tail gas vent pressure up to 7 kilograms, the liquid phase monomer is discharged from the tail gas vent pipe like snow, and the monomer compressor trips." Later, the hot water temperature of the low boiling tower reboiler was adjusted to 60 degrees. Close all exhaust condenser brine valves. Only when the top pressure of the low boiling tower and the exhaust pressure of the tail gas gradually decreased did the production gradually become normal. From "Close all exhaust condenser brine valves. Only when the top pressure of the low boiling tower and the exhaust pressure of the tail gas gradually decreased did the production gradually become normal. "If the backup exhaust condenser was not switched after the accident and the flow rate at the time of the accident was restored within a short period of time, it can be basically determined that the exhaust condenser was not blocked at the time of the accident. This post was last edited by Ideal Simulation on 2008-1-8 15:52 ]

Can this phenomenon be explained in this way?: 1. Excessive release of high boiling matter ---- The liquid level in the high tower is low ---- The pressure in the high tower drops ---- The feed valve from the low tower to the high tower is opened wide or remains unchanged because the pressure difference between the high and low towers is large --- The feed from the low tower is quickly fed to the high tower --- The liquid level in the low tower drops ---- The pressure drops --- Water separation and total condenser material flow into the low tower == Compressor outlet resistance is small == Air supply volume increases ==== Total condenser water valve is fully open==|| After the high tower liquid level is restored - after the feed valve is closed - there is too much material in the low tower - the pressure rises == the water separation material cannot be discharged == the full condensation cannot be discharged ---- the liquid phase enters from the total condenser gas phase pipe and the water separation tail cooling discharge pipe == tail condenser --- tail row discharge (snow) ---- the compressor outlet resistance is large - overload. 2. Distillation operation is a stable process. A sudden change in flow rate will cause the operation to go out of control, and the balance can only be re-established. 3. It is best to make a comprehensive analysis of the commissioning and interlocking of automatic control loops. 4. Because the process of the problem is not very clear, the analysis is based on general process assumptions. This post was last edited by edc1233 on 2008-6-1 06:49 ]

I originally studied mechanical and electrical engineering, and later graduated to work in chemical operations. Many things are half-understood, and problems cannot be solved. well!

I'll get all the data at that time and tell you tomorrow.

This issue should be addressed jointly by process and control personnel. Depending on the situation, I think the control parameters of the automatic valve are poor, and the controller has little understanding of the process, resulting in excessive overshooting of the control parameters, causing pressure fluctuations in the low tower system, causing material leakage from the tail row. If you want stable control, the system capacity should be larger, such as ； This problem can be avoided by maintaining a high liquid level in the distillation tower and by emptying the distillation tower less frequently when discharging high amounts of waste.