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  1. Mohammad Ka

    Problem in sour water stripper

    I do not understand why there is no sufficient steam @ 600kpag, 190C for injection at SWS bottom?! However, due to low thermal efficiency of DSG HX, MP is directly injected to DS via PV-B where the operating conditions of injected DS is 6.2barg and 210 C. It worth noting that the noticeable...
  2. Mohammad Ka

    Problem in sour water stripper

    Dear George I checked steam table and steam properties calculators and it is found that the saturated temp. at 75 kpag is 116.3C and at 85 kpag is 117.9 C. Here is the link: https://www.spiraxsarco.com/resources-and-design-tools/steam-tables/dry-saturated-steam-line By the way, the fouling in...
  3. Mohammad Ka

    Problem in sour water stripper

    Dear georgeverghese The stripper tower top pressure is 75 kpag (based on PFD). Material of the tubes is carbon steel. Based on the Lab. data, there is no chloride in dilution samples. Also pH=8.5-9.5 and conductivity=10-12 micS/cm. It should be noted that blowdown from steam drum to dilution...
  4. Mohammad Ka

    Problem in sour water stripper

    Hi everyone Mixed sour water and hydrocarbon stream from a quench tower is fed to a drum to separate heavy hydrocarbons from water. Then the separated sour water is sent to a coalescer for removing pygas from top and heavy components from bottom. The sour water from effluent of the coalescer...
  5. Mohammad Ka

    Problem in crack gas compressor start up

    georgeverghese, Talking with instrumentation engineers of the plant, it is revealed ASV on stage 5 could be activated by discharge pressure or FIC or MV by DCS operator or anti-surge algorithm internal controller as soon as reaching the min. governor speed. On the other hand, the activating...
  6. Mohammad Ka

    Problem in crack gas compressor start up

    rotw, - The maps are predicted. Can you please tell me how this solve the conflict? - I am using a third party simulator , AspenHysys. For sure, I do like to access the dropbox.
  7. Mohammad Ka

    Problem in crack gas compressor start up

    rotw, Thanks for your notes. 1- The mentioned gas composition is based on weight percent so in mole percent is 32.6% C2H4 + 20% C2H6 MWavg= 0.326*28.05 + 0.2 * 30.07 = 15.16 It sounds the data is correct. 2- For simulation of the compressor I used the ploytropic head and efficiency from the...
  8. Mohammad Ka

    Problem in crack gas compressor start up

    rotw, Thank you for your effort to simulate the phenomenon. 1- Yes, the first stage is a double flow machine. 2- I checked the MW and it is valid based on the vendor, design and laboratory data. 3- I have the same problem with discharge temperature in simulation of the CGC and it could be...
  9. Mohammad Ka

    Problem in crack gas compressor start up

    georgeverghese, Just three furnaces are used for start up. During the normal operation the number of furnaces in service shall be increased to meet the design capacity. As far as I remembered, I noted that " The ASV controller uses suction temperature and pressure, discharge flow, temperature...
  10. Mohammad Ka

    Problem in crack gas compressor start up

    rotw Thank you for your response In case of "fast opening and closing of a valve ...", a valve here refers to the check valve after the caustic tower and not a control valve. Appreciating for clarify the subject, the performance controller does not interfer the antisurge controller.
  11. Mohammad Ka

    Natural draft versus forced draft fire heaters

    Draft is calculated using the following formula D = 0.52 H × P(1/T - 1/T1)             in which D = draft produced (inches of water) H = height of stack (ft) P = atmospheric pressure (psia) T = absolute atmospheric temperature T1 = absolute temperature of stack gases. The height of stack is a...
  12. Mohammad Ka

    Problem in crack gas compressor start up

    rotw The turbine speed controller and antisurge controller has been decoupled and no interference has reported yet.
  13. Mohammad Ka

    Problem in crack gas compressor start up

    hacksaw No abnormal conditions were observed in furnaces during the runs. Outlet temperature, pressure and gas composition all were in the normal range.
  14. Mohammad Ka

    Problem in crack gas compressor start up

    georgeverghese here is the data for ASV 1 & 2: ASV 1 : 187 t/h (min.) , 277 t/h (normal) ASV 2 : 80 t/h (min. at 80% speed) , 277 t/h (normal) Do you believe that these specifications may cause problems in start-up of the compressor? And can you please describe more your...
  15. Mohammad Ka

    Problem in crack gas compressor start up

    rotw, How can I give you the data?
  16. Mohammad Ka

    Flash Drum VLE

    What are the inlet composition,P, T and outlet P of the valve? Can you explain more about the overhead pressure?
  17. Mohammad Ka

    Problem in crack gas compressor start up

    Dear georgeverghese I checked the specifications of the ASVs and found these valves are suitably sized for recycling 170-200 t/h gas flow at 90% of full speed. It should be noted that the plant has been producing since 2004 and the CGC has successfully started many times. I prepared the trends...
  18. Mohammad Ka

    Problem in crack gas compressor start up

    Dear georgeverghese After opening and checking the CGC, opening and fully cleaning the caustic tower, the plant was started. This time the compressor started with no problem and the plant is in normal operation now. since no obvious evident has been detected in the CGC, I checked the trend of...
  19. Mohammad Ka

    Problem in crack gas compressor start up

    TT on stage 5D and other transmitters are checked. All calibrated. There are some paradoxes in operating manual and process data sheets documents: 1- When 3 furnaces are fed with feed stock and one in hot stand by conditions with all effluents diverted to quench water tower, the crack gas...
  20. Mohammad Ka

    Problem in crack gas compressor start up

    a) ASVs were sent to shop. No failure or plugging for both valves has been seen. b)as far as I know from the last normal operation to now, modification or adjustment has not been made to CGC antisurge control or setting. However, it should be checked. c) CGC stage 4 & 5 were opened. Every thing...

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