Sulzer Chemtech
Tower Technical Bulletin Troubleshooting distillation columns – Part 1: The basics Background
Properly designed and operated distillation columns can provide long-term, trouble-free service. However However,, mechanical failure, process upsets, and other factors can occur, preventing the distillation system from achieving the expected design performance. Taking a tower off-line is time consuming and expe nsive; before doing so it is important to have a good idea of what is causing the problem. A systematic study of the column should be made (often with the assistance of the column equipment provider). After careful study, a tower inspection should be perform ed to confirm the cause of the problem and to determine and/ or provide a proper solution. In emergency cases, expected replacement equipment may need to be on site prior to the column opening.
Where to start
Ask yourself the foll owing questions: • What specications are not being met? What could happen internally to create this issue? • Is this a capacity problem? Has the column ever run successfully at these rates? If not, the internals may be at
their capacity limit. • Have there been any upset conditions that may have damage internals?
Understanding Understandin g mass transfer fundamentals is critical
Knowledge of the column thermodynamic and hydraulic functions is the key key starting point. Any problem that develops develops that does not allow the vapor and liquid to contact each other in the manner for which the device was designed, or keeps the vapor and liquid from separating after contact, will adversely affect column performance. For example, example, the packing shown below will not provide good flow or vapor/liquid contacting efficiency because some of the packing is blocked off by fouling.
Working toward a solution
The simple checks should be made first. Check the instrumentation to ensure that flows, levels, temperatures, and pressures are correct. Check to make sure that feed compositions and analyses are correct. Conduct a single gauge pressure survey and a temperature survey as possible. Perform a mass balance across the column—a closure of 3-5% is normally considered acceptable. Once you have this information, review the information with plant engineering and operations. Consult with your equipment vendor to further investigate the problem. Decide on the feasibility of a column gamma scan. If practical, schedule a tower inspection at the first opportunity in order to personally examine the internals. In the meantime, the problem may be temporarily alleviated by reducing rates, changing the reflux and reboiler duties, changing the feed location, and increasing or de creasing the tower pressure. The Sulzer Applications Group
Sulzer Chemtech has over 150 years of in-house operating and design experience in process applications. We understand your process and your economic drivers.
Sulzer has the know-how and the technology to design internals with reliable, high performanc performance. e. Hydraulic evaluation
Symptoms of hydraulic flooding include excessive or erratic pressure drop, reduced bottoms flow, reduced column temperature profile, and excessive liquid carryover. Conversely, low pressure drop is an indication of missing trays or packing.
Sulzer Chemtech, USA, Inc.
8505 E. North Belt Drive | Humble, TX 77396 Phone: (281) (281) 604-4100 604-4100 | Fax: (281) (281) 540-2777 540-2777 Email: TowerTech.CTUS@sul
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Legal Notice: The information contained in this publication is believed to be accurate and reliable, but is not to be construed as implying any warranty or guarantee
of performance. Sulzer Chemtech waives any liability and indemnity for effects resulting from its application.
