The temperature at the bottom of the stabilizer is high and the propylene content in the liquefied gas is low; what could be the reason?
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In recent days, the temperature at the bottom of the stabilizer has been high, and tests have shown a decrease in the propylene content in the liquefied gas. Could you please explain the reason for this?
Are there any changes in the operation of the parsing tower?
There are no significant fluctuations in bottom temperature or pressure
The propylene content seems to have little to do with the operation of the stabilizer tower. Has there been any adjustment in your reaction unit? Also, has the nature of your raw materials changed?
If there are no changes in the reaction conditions and it’s simply the high temperature at the bottom of the stabilizer that results in a low propylene content, my understanding is that when the temperature at the bottom of the stabilizer is high, the C4 and C5 components evaporate back upward (this can be determined by checking the test results of the liquefied gas and the stabilized gas). In the liquefied gas sample, due to the increased proportion of other components, the propylene content appears lower; however, this doesn’t necessarily mean that the actual amount of propylene has decreased.
How to change the propylene content by stabilizing the bottom temperature
I’m not sure either, that’s why I asked Is it true that the bottom temperature has little impact on the propylene content in liquefied gas, with key factors lying elsewhere such as the properties of the raw materials and the reaction temperature?
It means changing the base value for liquefied gas. But even if the bottom temperature is high, isn’t it still necessary to control the vapor pressure? With this indicator in control, the amount of C5 component at the top won’t increase; therefore, there is some impact, but it’s likely to be minimal. If the propylene content changes not significantly (by more than 2%), then it has little impact on the base temperature. By the way, if your liquefied gas is sampled using a cylinder and analyzed by gas chromatography, the results will differ significantly depending on whether the analysis is conducted immediately after sampling or after waiting 1–2 hours. Heavier C5 compounds adhere to the inner wall of the cylinder, leading to an increase in the propylene content; this is also a factor that affects the baseline values.
The components of liquefied gas have become heavier; the levels of C4 and C5 have increased, while the propylene content has decreased. This should be normal