【Chemical Process Operations】Propylene Column Reboiler
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This post was last edited by Xiao Gong 1985 on 2016-3-11 at 09:28. Since the only utility available on-site is steam, with a pressure of 0.35 MPaG, the corresponding temperature is quite high, over 150 degrees; meanwhile, the operating temperature at the top of the tower is 59°C. The calculated heat transfer temperature difference is 85°C, and the overall heat transfer coefficient is 1400 W/(m²·K). With such a high heat transfer temperature difference and heat transfer coefficient, will it be possible to operate the reboiler stably in the future? I hope experienced experts can give me some guidance!
Consider using a temperature reducer to lower the temperature.
No problem; the propylene column is designed to operate with a high reflux ratio, so just control the top temperature properly
No problem, we can handle saturated steam at 0.6 as well. .
What is the relationship between the temperature of the heat source at the bottom of the tower and the temperature at the top of the tower?
The temperature isn’t high either, is it? It’s normal; the operation is fine! ! !
Thank you all for your replies! It is the temperature at the bottom of the tower that is 59°C. Saturated steam at 0.6 pressure can be operated stably; it seems that a large temperature difference isn’t a problem, though there is some energy waste!
I don’t understand. I just know that steam with a pressure of 0.4–1.0 MPA can be used as a heat source; if the temperature difference is large, isn’t it possible to use less amount of steam? There shouldn’t be any problem with that… I’m not sure what your question is… The temperature difference between the heat source and the medium determines the material required for the heater, right? It’s like boiling water; as long as there is water, the temperature won’t get too high.
Temperature is important; if it is too high, bubbles will form on the surface of the tubes in the reboiler, increasing the heat transfer resistance and reducing the efficiency of heat exchange. Therefore, the difference between the steam temperature and the saturation temperature at the bottom pressure of the tower should not be too large.
I think you still haven’t understood this problem! Reboilers that use steam as a heat source utilize not the heat from the temperature difference between steam and the heating medium, but rather the latent heat released when steam turns into condensed water! The sensible heat is minuscule compared to the latent heat of steam! To determine whether a reboiler is suitable, you need to consider the processing load per unit time and the heat that needs to be supplied; what’s the use of just thinking about the temperature difference! After all, whether it’s 1.0 MPa or 0.35 MPa, steam heating isn’t effective; it is the latent heat released when steam condenses into condensed water that plays the key role!