How can you troubleshoot distillation columns?

1 Identify the symptoms

Troubleshooting distillation columns begins with identifying the symptoms that indicate a problem. These can be determined from the column's operating conditions, such as pressure, temperature, flow rates, and compositions, or from the physical appearance of the column, like vapor plumes, noise, or vibration. Common symptoms include a high or low pressure drop across the column or a section of the column, an unstable or oscillating operation, excessive heat or cooling duty, and abnormal tray or packing behavior like flooding, foaming, weeping, or dry spots. Additionally, you may observe a high or low reflux ratio or boil-up ratio and high or low product purity or recovery. Off-specification products or intermediate streams are also indicators of a problem.

2 Collect and analyze data

The next step in troubleshooting distillation columns is to collect and analyze data that can help you diagnose the problem. You need to gather historical and current data from the column's instruments, such as pressure gauges, temperature sensors, flow meters, and analyzers, as well as from the column's design and simulation models, if available. Additionally, you should inspect the column's internals for any signs of damage, corrosion, fouling, or misalignment. To analyze the data, you can use various tools and techniques such as plotting operating curves like McCabe-Thiele diagrams or HETP charts, performing mass and energy balances around the column and its sections, calculating the column's efficiency, capacity, and loading factors, comparing actual and expected performance of the column and its components, and identifying any deviations or trends from normal or design conditions.

3 Find the root causes

The third step in troubleshooting distillation columns is to find the root causes of the problem. To do this, you need to use logic and evidence to narrow down the possible causes and eliminate the unlikely ones. To help you find the root cause, you can use the 5 Whys technique, which involves asking why a problem occurred and then asking why again until you reach the root cause. Additionally, you can use a fishbone diagram, which helps you organize potential causes into categories. Alternatively, you can apply a fault tree analysis, which traces the problem back to its origins by using a tree-like structure of events and conditions.

4 Implement corrective actions

The final step in troubleshooting distillation columns is to implement corrective actions that can solve the problem and prevent it from recurring. You need to evaluate the feasibility, effectiveness, and cost of the possible solutions before deciding on the best one. Additionally, you must test and monitor the results of the solution and document the lessons learned. Common corrective actions include adjusting the operating parameters, such as pressure, temperature, flow rates, and compositions; replacing or repairing damaged or faulty equipment; cleaning or removing fouling or plugging materials; and modifying or upgrading the column's design or configuration. For example, you could add or remove trays, change the packing type or size, or install internals.

5 Here’s what else to consider

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