Operating characteristics of the MTBE catalytic distillation column
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Recently, the operation of the MTBE catalytic distillation column in our facility has been extremely unstable; the quality of the MTBE produced is often substandard. The temperature at the top of the catalytic distillation column is high, but the temperature at the bottom fails to increase. Multiple adjustments to the alcohol-to-olefin ratio have yielded no significant results; I seek advice from those with more experience. Thank you!
You can be more specific; it would be best to provide actual figures, or send me an email
The operation of the MTBE catalytic distillation column is extremely unstable; the MTBE product often fails to meet quality standards. The temperature at the top of the column is high, yet the temperature at the bottom fails to increase. Multiple adjustments to the alcohol-to-olefin ratio yielded no significant effect. The specific conditions are as follows: C4 feed at 19.3 t/h, methanol at 2.3 t/h, with an additional 48 kg/h of methanol added. The pressure in the mixed-bed reactor is maintained around 0.6 MPa, while the temperature is approximately 63 degrees in the upper, middle, and lower sections. The pressure in the lower section of the catalytic distillation tower is controlled at 0.5 MPa; the bottom temperature is around 124 degrees, and it does not exceed 125.5 degrees. The top temperature is around 65 degrees. The pressure in the upper tower is 0.49 MPa; the external reflux rate is 10.3 t/h, while the internal reflux rate is 28.9 t/h. The temperature in the reaction section of the upper tower is around 52 degrees. Since our 70,000 t/year MTBE plant has been in operation for just over two months, another problem has been identified recently: the C4 tank after etherification always contains methanol. The level in the extraction tower is around 40%, and the methanol at the bottom of the methanol recovery tower cannot be vaporized either; the methanol content there is also around 40%. Sampling and testing in the methanol recovery tank are not possible, as the gasification is too severe.
Your plant’s MTBE process is quite different from mine, so it’s hard for me to comment! There must be some issues with the operation of your methanol recovery unit: 1. What is the temperature at the bottom of the recovery tower? 2. What is the pressure in the extraction tower? 3. Is the two-tank return flow control appropriate? Additionally, my humble opinion is that the methanol content in the bottom of the recovery tower is too high; adjusting it to over 80% should have an effect
1. Pay attention to analyzing the content of carbon five and water in the raw material carbon four to determine whether it exceeds the specified limits 2. Since the feed and discharge compositions are not provided, the amount of methanol cannot be determined. 3. The bottom temperature of the catalytic distillation column is too low; it is possible to analyze the composition of the material exiting from the bottom of the column. If the MTBE level is within the specified range, the issue may lie with the instruments or pressure controls. 4. Unstable operation of the catalytic distillation column is related to its startup; if necessary, full reflux can be used to stabilize it before proceeding further. 5. Check the water-to-oil ratio regularly in the C4 tank after etherification to ensure it is normal. 6. Methanol vapor cannot rise from the bottom of the methanol recovery tower; check the tower pressure – it’s possible that there is carbon tetrahydrocarbons present. 7. Where is the technology provider located? There shouldn’t be so many problems, right?
It must have contained C4; the laboratory saw boiling occur when methanol was heated.