How to choose the dotted line for fillers in Echt’s general association diagram

The selection of the dotted lines for the packing in Echter’s general correlation diagram is based on operating conditions and packing type. In an Echt diagram, first determine the operating pressure and temperature of your system, then find the corresponding saturation line based on the type of packing selected. Select the general dot line that matches or is closest to your operating conditions to ensure that the packing can function properly under the designed conditions. .

Hello, thank you for your reply! The design conditions here are normal pressure and 20°C; hydrogen chloride gas is absorbed using water spray, and the packing used is DN38 plastic Pall rings. Based on the article \"He Hongyang – Comparison of Calculation Models for Head Loss/Drop in Packed Columns,\" I selected a packed column pressure drop of 30 mmH2O/m for the case of absorption with no foaming in the system. Do you think this is appropriate?

Hello! Based on the design conditions you provided (atmospheric pressure, 20°C, water spray for the absorption of hydrogen chloride gas, and the use of DN38 plastic Pall ring packing), it is a reasonable choice to adopt the pressure drop standard of 30 mmH2O/m mentioned in the article \"He Hongyang – Comparison of Calculation Models for the Bubble Point/Pressure Drop in Packing Columns\", which corresponds to absorption with no foaming in the system. When designing a packed tower, it is crucial to ensure that the selected pressure drop value allows for good gas-liquid flow within the tower, high mass transfer efficiency, and stable operation. At the same time, the plastic Packed Ring DN38 is more suitable for handling corrosive gases such as hydrogen chloride due to its excellent gas-liquid contact properties and low pressure drop. In summary, your choice is reasonable. It is essential to continuously monitor the conditions inside the tower during design and operation to ensure the viability and safety of the design parameters. If necessary, it is also possible to consider further consultation with professional chemical engineering designers for confirmation. .

Thank you so much for your help! I have another question: After choosing a pressure drop of 30 mmH2O/m, calculating the tower diameter and the height of the packing layer based on the resulting values, I recalculate the horizontal and vertical coordinates using those data. On the Ektar diagram, the pressure drop across the packing layer is found to be 10 mmH2O/m, which is quite different from the previous value. What could be the reason for this? Does it affect the operation of the packed tower?

When you design a packed tower and find that the recalculated pressure drop across the packing layer differs significantly from the original design value (from 30 mmH2O/m to 10 mmH2O/m), there could be several reasons for this: 1. **Calculation errors**: Designing a packed tower involves multiple variables and assumptions, and deviations between the initial calculations and the actual conditions can lead to substantial differences in subsequent recalculations. Ensure the accuracy of all input data and the correctness of the calculation methods. 2. **Changes in operating conditions**: Changes in the density, viscosity, or flow rate of the fluid inside the tower can affect the pressure drop. Ensure that all operating conditions remain consistent with the original design. 3. **Relationship between pressure drop and flow regime**: A lower pressure drop may indicate a lower gas-liquid contact efficiency, which can affect the overall mass transfer efficiency of the tower. Generally, a high pressure drop indicates intense gas-liquid mixing, but it also means higher energy consumption and potential operational problems such as clogging. 4. **Incorrect chart interpretation**: When using Echter’s general correlation diagram, make sure to read and interpret the data on the chart correctly. Misinterpretation can lead to deviations in the calculation results. **Impact on tower operation**: Too low a pressure drop may result in insufficient gas-liquid contact, thereby reducing the absorption efficiency or the efficiency of other mass transfer processes. In some cases, low pressure drop can also cause flow instability within the tower, such as oscillations or channeling. It is recommended to conduct a detailed evaluation of the design parameters, and adjust the tower diameter, packing height, or operating conditions as necessary to achieve an optimal operating condition. If you encounter difficulties during the design and calculation process, you may consider consulting a professionally experienced chemical process engineer or using more advanced simulation software for design verification and optimization. .

Thank you very much for your answer! Thank you!

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