Analysis of the reasons for the excess level of liquid hydrocarbon C5 in the absorption stabilization system
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Recently, the C5 content in the liquid hydrocarbons at our facility has exceeded the specified limit (our target is ≤2.8). Could anyone give some advice? What could be the cause? The stabilizer pressure is 0.95 MPa, and the low temperature at the reboiler outlet is 216℃
Is the bottom temperature a bit high? Maybe increase the pressure, or raise the recirculation flow
Is the top temperature of the stabilizer too high?
Analyze as follows: 1. Are the reboiler outlet temperature and the sensitive tray temperature too high? 2. Is the steam pressure too low? 3. Feed temperature and feed composition 4. Has the feed location changed? 5. You can try increasing the operating pressure. 6. If none of these issues exist, then the most likely cause is water being carried in with the feed or reflux.
The saturated vapor pressures of C5 and gasoline are a contradictory pair; it is necessary to find a suitable pressure and temperature. I don’t know the specific details, and it’s hard to determine whether this temperature is appropriate
This post was last edited by wyt1234 on 2010-10-14 at 18:04. The bottom temperature at the reboiler outlet is 216°C, which is too high; it needs to be reduced, with the top temperature of the stabilizer controlled at 65°C–70°C. Adjust operations in a timely manner to maintain stable temperatures, pressures, flow rates, and liquid levels in the stabilizer tower. Maintain stable feed and drawoff rates in the stabilizer tower.
I would recommend the following operating parameters: a processing capacity of 120,000 tons for the absorption and stabilization system; the temperature at the bottom of the stabilization tower should be between 176–186°C, while the temperature at the top of the tower should be between 58–64°C. In fact, there is a close relationship between the temperature at the bottom of the tower and the processing capacity – when the processing capacity is high, more liquefied gas is produced, so the temperature should be increased accordingly; if less liquefied gas is produced, the temperature can be reduced slightly. Reflux ratio 1-1.1
Is the temperature at the bottom of the tower high? Is the tower top temperature high? What is the processing capacity? Our temperature control is set at 54-60, with a pressure of 0.8-0.9 Mpa; the liquefied gas meets the standards! Control it to stay at the lower limit during operation!
Top temperature 56, low temperature 180. Pressure 0.96
The conditions mentioned on the ninth floor are acceptable; if the product does not meet the standards, appropriate adjustments can be made. By appropriately lowering the temperature while ensuring that the vapor pressure of gasoline remains within acceptable limits, and by increasing the reflux ratio slightly, it should be possible to achieve the desired parameters
For reference only: Our column reflux ratio is around 1.7, the bottom temperature of the column is about 175 degrees Celsius, the top pressure is 1.1 MPa, and the feed rate is 110 tons. LPG C5 1.5% (by volume)