Seek guidance on tower design
Thread Content
It is suspected that the light components in the company’s products are above the specified limits; the purity of the products is around 99%, and the identity of these light components is unknown. Therefore, it is planned to design a new distillation tower based on the existing equipment. The reflux ratio of the primary tower was previously around 10; with the addition of a secondary tower, no reflux occurs in the primary tower, and all reflux is directed to the secondary tower. The primary tower is a packed tower – so what aspects need to be considered when designing the secondary tower? Is the feed to the second tower based on the amount of steam rising from the first tower as the feeding condition? If all the reflux occurs in the secondary tower and the top condenser is reused, is it necessary to add a reboiler to the bottom of the secondary tower? Looking at the calculation steps in Chemical Engineering Principles, the material balances all show imbalances... I have little experience with double-tower designs and don’t know where to start... Seeking guidance
I’m not a designer; I’m just expressing my opinions out of curiosity, for reference only. First of all, the existing problems have not been clearly identified, so it is indeed difficult to figure out how to address them. Should the equipment design unit be involved in the consultation to check whether the parameters meet the relevant process conditions of the original design as well as those of on-site production? Through comparative analysis, it is possible to identify the existing problems, and then explore whether developing solutions would make things better. Blind technological upgrades rarely yield the expected results.
The boss gave the order; let’s get to it.
They probably want to save on design costs; that makes it quite difficult. It becomes quite troublesome when the production department is directly responsible for the technical upgrades without the involvement of the original design team; without the original design parameters, it takes a long time to conduct research from scratch, and there is no clear direction to follow. For reference only; you can look for similar devices to see if there are similar issues and learn from others’ experiences.
:L Do you want to raise the tower and change it from a straight tower to a side line? Reduce the amount of light components in the product?
The second option is this; for now, the idea is to add a secondary tower first: (
This post was last edited by Qingcheng Jun on 2020-12-21 at 14:44. The production department should take the lead in carrying out technical upgrades; even if no design firm is hired, it’s still necessary to find reliable people to handle the design work – at least those who understand the principles of distillation. If the processing volume remains unchanged, using the old data for tower diameter and height generally does not cause flooding. It’s unlikely that you can add another level on top of the existing tower; instead, you should build another tower behind it. No backflow at the first stage yet? What is a tower without reflux and without any material exchange called? Unless there is secondary reflux that feeds back to the primary stage, reflux is required for both the primary and secondary stages. To stack them together and increase the height of the tower, the height of the existing condenser must be increased or reflux must be pumped in. Distillation tower design is a highly complex systems engineering task; those who undertake it must be prepared to accept the risk of failure, and it can only be carried out in an environment where there are no safety inspections or enforcement measures. If a layperson with no knowledge of chemical engineering processes could design it after reading a few books, and if some welders could get the job done. The design institutes and security checks are driving people crazy with hunger
If you want to add a second tower, as mentioned above, the first tower remains unchanged. For the second tower, apart from its height, you can completely replicate Tower No. 1; everything else will be essentially the same (the heat exchanger can be smaller). The height of the tower needs to be determined based on your material requirements. You can estimate it using the existing towers you have. It’s fine if the tower is made taller; just make sure it’s not too short； If you don’t have technical support, it might be easier to increase the height; it depends on your building design. Moreover, the fixed costs and operating expenses for the latter option are much lower ；
It is necessary to determine clearly whether it is caused by an excessive level of light components in the feed. If it is confirmed that this approach is feasible, then a primary tower should be used to evaporate away the excess light components, and the liquid from the bottom of that primary tower should then be fed into a secondary tower. This will meet your requirements.
It is recommended to hire professional designers for the design work; the money spent on this is necessary. Designing it yourself may require even more investment, and if it fails, the costs will be much higher, not to mention the time lost. If it is confirmed that the light components are above the specified level, a light-end removal tower can be added; the existing product tower can remain unchanged