Can a naphtha hydrocracking distillation column use a reboiler?
Thread Content
The question is: Is a reboiler typically used at the bottom of a gasoline hydrocracking fractionator to prevent olefins from coking? After hydrogenation, the naphtha is fed into a fractionation tower to separate the products; 80% of the product must be taken from the top of the tower, which results in a high load on the fractionation tower. Can a reboiler be used? How can the tower load be reduced when a large amount of product is extracted from the top of the tower? I hope experts can provide guidance and insights; thank you!
1. The use of a reboiler is not to prevent olefin coking, but rather to make full use of the plant’s heat source and reduce the operating costs and energy consumption of the plant； 2. 80% of the product should be taken from the top of the distillation tower. Have you changed the distribution of the product within this tower? Under normal circumstances, the design should be sufficient to meet the process requirements; if changes have been made, those can be compensated for by adjusting the process parameters. By ensuring the quality of the product while reducing the pressure at the tower top and increasing the temperature at the extraction point, the process requirements can still be met.
Well, for gasoline hydrogenation, a reboiler can be used. I’ve seen that neither the petroleum universities in China nor the company AXENS abroad use reboilers; moreover, when using a reboiler, it is necessary to reduce the steam temperature to over 200 degrees for heating, which imposes requirements on the temperature of the heat source. How can we reduce the tower pressure while increasing the temperature of the vapor drawn from the top of the tower? I reduced the tower pressure to 0.15 MPa.G, and the top temperature of the tower was only 50°C.
All of the things you mentioned are determined by the properties of the medium and various parameters. 1. The bottom reboiler of the gasoline hydrogenation stripper does not require much heat; if a small reboiler is used, the investment cost and energy consumption will be much higher than those of the reboiler itself ； 2. “Reboilers are used to reduce the steam temperature to over 200 degrees for heating,” and this is because the medium being heated is gasoline; the property of gasoline is that the lighter its components, the higher its vaporization rate ； If the temperature of the heating medium is too high, it will cause the gasoline to vaporize instantly inside the reboiler, resulting in a sharp increase in pressure, which can easily lead to gas blockages within the reboiler ； Therefore, the control of the heat source temperature in the reboiler at the bottom of the gasoline tower is determined through calculations based on parameters such as the heat required by the stripping tower, the flow rate of the fluid within the reboiler, the vaporization rate, the heat exchange area, as well as investment costs and energy consumption during processing ； 3. It’s not about \"how to reduce the tower pressure and temperature by lowering the temperature of the heat source\"; the adjustment of the product is carried out based on the results of analytical tests. There are actually many ways to make such adjustments – the feed temperature, the bottom temperature of the tower, the top temperature of the tower, and the tower pressure can all be used as means to adjust the product distribution.