hswang2
Civil/Environmental
- Oct 27, 2006
- 53
I have tried to figure out how to get the entrainment from the vaprozer. In this process, the multicomponent feed reactor is vaporize in the system shown in the attached graph. Liquid reactant feed enters a horizontal kettle vaporizer that is heat by a process stream. Vapor goes to a knockout pot to remove entrained liquid and then to a stream heated superheater and thence to the reactor. The bottoms from the kettle vaporizer are fed by gravity to a separate blowdown drum. The blowdown drum is heated with a steam coil with the vapor joining the feed to the knockout pot. The bottoms of the blowdown drum contain unwanted high boilers and are removed from the system. The knockout pot has a demister. The liquid from the knockout pot returns by gravity to kettle vaporizer. The demand for product has increased and to meet the demand the feed to the vaporizer has been increase. The result has been that the level indictor in the knockout pot signals a high level. Any additional increase in feed gave a sudden and sever drop in vapor temperature into the reactor. Erratic reactor temperature follows. We need to meet the increase demand. If the feed is reduced to the lower rate, normal performance occurs.
Initial evidence we observed
1. Hi level alarm KO
2. Tem sensor ex supuerheater low.
3. Reactor temp sensors erratic
4. Symptoms disappear for normal feed to vaporizer.
Possible hypotheses
1. Entrainment from the vaporizer. (does this really make the temperature read low, and how to calculate the entrainment from vaporizer?)
2. Steam leak into blowdown.
3. Steam leak from superheater into vapor.
4. Vaporizer bottoms rises up into knockout drum (seems not make sense to me
Is that too much feed to cause liquid level rises up into knockout drum)
5. Drain line from knockout pot too small or plugged
6. Steam boils too much Blowdown vapor into the KO and entrains liquid.(entrain liquid is mean much more vapor surrounding the small amount liquid?)
7. Level in vaporizer lower than normal
8. Blowdown level controller reading low or is frozen level sensor on KO pot faulty
Action.
1. Calculate entrainment from vaporizer.
2. Record level gauge read KO pot as increase feed rate
3. Calculate press profile vapor
4. Measure P via sensors in KO and Blowdwon.
Conclude:
1. Pressure drop very high between vaporizer and KO and relatively low from KO to reactor. Calculations show liquid would flow from bottom of vaporizer into KO.
2. Enlarge line, minimize fittings, change valve in line from vaporizer to KO
Thank you very much.
Initial evidence we observed
1. Hi level alarm KO
2. Tem sensor ex supuerheater low.
3. Reactor temp sensors erratic
4. Symptoms disappear for normal feed to vaporizer.
Possible hypotheses
1. Entrainment from the vaporizer. (does this really make the temperature read low, and how to calculate the entrainment from vaporizer?)
2. Steam leak into blowdown.
3. Steam leak from superheater into vapor.
4. Vaporizer bottoms rises up into knockout drum (seems not make sense to me
Is that too much feed to cause liquid level rises up into knockout drum)
5. Drain line from knockout pot too small or plugged
6. Steam boils too much Blowdown vapor into the KO and entrains liquid.(entrain liquid is mean much more vapor surrounding the small amount liquid?)
7. Level in vaporizer lower than normal
8. Blowdown level controller reading low or is frozen level sensor on KO pot faulty
Action.
1. Calculate entrainment from vaporizer.
2. Record level gauge read KO pot as increase feed rate
3. Calculate press profile vapor
4. Measure P via sensors in KO and Blowdwon.
Conclude:
1. Pressure drop very high between vaporizer and KO and relatively low from KO to reactor. Calculations show liquid would flow from bottom of vaporizer into KO.
2. Enlarge line, minimize fittings, change valve in line from vaporizer to KO
Thank you very much.
