Various problems encountered by the low-pressure depropanizer tower during the start-up and operation of the unit.

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In the olefin industry, the high and low pressure depropanizer system plays a role in separating carbon two/carbon three and carbon three/carbon four components. In the methanol to olefins and steam cracking ethylene processes, the process flow designs for this column system vary. It is nothing more than whether the top of the high-pressure tower goes to the compressor inlet or the top of the tower for propylene distillation, and the top of the low-pressure tower returns to the high-pressure tower for reflux or goes directly to the C3 hydrogenation system. Various problems encountered by the low-pressure depropanizer tower during the start-up and operation of the unit. 1. During the start-up of the device, the tower pressure is extremely high and the safety valve takes off (there are interlocking and non-interlocking when the tower pressure is high). 2. The mechanical seal of the reflux pump of the low-pressure depropanizer tower leaks (whether there is an emergency isolation valve at the pump inlet). 3. The top temperature of the low-pressure depropanization tower is high and the pressure is low (the C4 content at the top of the tower is too high). 4. The low-pressure depropanizer tower kettle brings a large amount of carbon dioxide into the debutanizer. 5. The high-pressure depropanizer tower tank carries carbon dioxide into the low-pressure depropanizer tower. 6. The low-pressure depropanizer tower is flooded and flooded with liquid. 7. The reboiler is scaled and needs to be replaced and inspected. 8. The refrigerant in the tower top condenser is interrupted (the propylene machine stops or the liquid control valve suddenly closes). 9. The heating medium of the reboiler is interrupted (the heating medium is interrupted or the valve is suddenly closed). 10. The return pump trips and stops due to failure, and the return valve is fully open (the return valve is FO). 11. Flange mouth leakage (often encountered during the original start-up process). 12. The system is overloaded and the feed composition deviates greatly from the design (the raw materials deviate from the design during the operation period). 13. Low-pressure depropanizer tower overhead condenser ultra-delay control loop (the specific implementation methods of control loops in different devices are different, switch-type ultra-delay and continuous-type ultra-delay). 14. During the initial start-up, the pump inlet filter was clogged (a common occurrence during the start-up period). 15. The low-pressure depropanizer tower LCB low-temperature gate valve is installed in the wrong direction (often occurs during construction). 16. Problem with the injection amount of polymerization inhibitor in the depropanizer tower. S&W High and Low Pressure Depropanizer System SEI Low Pressure Depropanizer (Single Tower) Low Pressure Depropanizer of Lummus Twin Tower System S&W High and Low Pressure Depropanizer System Lummus Twin Tower System in Sequential Separation