Blockage in polypropylene production unit D-501

D501? What is it? A steaming tank?

It’s the steam pot! The powder doesn’t stick, right? 1

:) Although your question isn’t phrased very accurately, I’m more than willing to help you clarify it. Based on a comprehensive overview of the second-generation twin-screw polypropylene production process developed in France for use in liquid-phase systems, I will now summarize the common faults, their causes, and the steps for handling them in the steaming system (including steam generator D501): 1. Problem: Low pressure difference between bag filter F301 and the steam generator ； Possible reasons: 1) Low level and pressure in bag filter F301 ； 2) High pressure in the steam generator ； Solution: 1) Check the feed rate from the flash tank to F301. Close the outlet valve LIC311 of the bag filter. Check the pressure of the bag filter, PIC311. 2) Check the feed rate from the flash tank to the bag filter, as well as whether the level and pressure of the bag filter are normal; reduce the flow rate at LIC311. Check the inlet pressure of compressor PK501 and report the loading condition of the air compressor. 2. Problem: High pressure in the steamer ； Possible cause: 1) The return air compressor has stopped ； 2) Low level in bag filter ； 3) The return air compressor is not loaded ； 4) Obstruction in the T501 tower top gas stream ； Solution: 1) Reduce PIC501 to control pressure and restart the compressor. 2) Increase the level of material in the bag filter. Check the pressure difference gauge between the steamer and the bag filter to confirm that the pressure difference is appropriate. 3) Check the valve position of the compressor inlet pressure controller. Check the outlet pressure of the compressor; if necessary, reduce PIC512. Check the level of material at the return gas outlet separator D504. Check the material level in compressor inlet K.O. tank D505. 4) Check the level of material in wash tower T501 (I503). 3. Problem: High gas temperature in the steamer scrubber tower ； Possible cause: Insufficient heat exchange ； Solution: Check the water circulation volume of the scrubber tower. Check the temperature changes of the heat exchanger. Check the process water flow at the pump inlet. Reduce the steam volume of FIC504. 4. Issue: Unstable material level and pressure in the steamer ； Possible reasons: 1) There may be products with low stereoregularity ； 2) The return air compressor is not loaded ； 3) The steam generator level gauge is broken ； 4) Instability in the pressure of the steamer can cause instability in the material level. Solution: 1) Check whether the powder inside the bag filter is sticky. Check the flow of DONOR and reduce the TEAL/DONOR ratio. Check the level indicator of the bag filter, and manually operate the steam generator outlet valve and the bag filter outlet valve. 2) Check the outlet pressure PIC512 of the return gas compressor. It may be necessary to restart the compressor. 3) Manually control LV501. 5. Issue: Low temperature in the steam generator bed ； Possible reasons: 1) Inaccurate level indication or steam malfunction ； 2) Low pressure in the steamer jacket ； Solution: 1) Check the pressure and temperature of the steam at FIC501 and FIC502. Increase the level of material in the steamer. Check the flow rate and inlet pressure of the steam going to the vaporizer. Check the steam trap on the vaporizer outlet line. 2) Check the operation of the jacket steam control valve. Verify the pressure of PV506. Check whether the strainer is working properly. 6. Issue: Low pressure in the steamer ； Possible causes: Low feed rate from the bag filter or compressor failure ； Solution: Check the valve position from the recycle gas compressor to the vaporizer. Check the suction pressure at the air compressor site and the position of the pressure control valve. 7. Question: PK501 is stopped ； Possible reasons: 1) Low suction inlet pressure ； 2) Outlet pressure is very high ； 3) D505 temperature is too high ； 4) Low low level of material D505 (I506). Solution: Identify the cause and restart the compressor. :)

This post was last edited by ajie8352 on 2009-12-13 at 20:04. It seems there is a problem with the discharge process; it might be necessary to check the pressure of LV501, or perhaps the pressure in D502 is too high.

My clog happens very easily at the start of operation!

If there is a blockage at the start of operation, you can set D501 to a direct connection at the beginning; in other words, do not establish a material level for D501 at that time, but instead establish a material level for D502 first. Once things stabilize, and it is confirmed that there are no issues by taking material from AC25, then you can establish a material level for D501

Which grade does the manufacturer’s equipment get clogged when producing? This issue generally does not occur with homopolymer grades

Reply to 8# sinock902: It doesn’t seem very appropriate to build the level in reverse; the hydrocarbon content in the subsequent system will be very high, which is quite dangerous! I think the blockage that occurs at startup is related to the steam from D501 being introduced too early. Generally, after starting the steam supply from D501, we keep the valve for LV501 open at around 5% capacity, and at the same time activate the drying system of D502, in order to prevent liquid accumulation inside D501 and D502 from causing difficulties in discharging material! The effect is pretty good!

Take a photo of the block removed from D501 and upload it.