Nitrogen seal flow rate calculation

The calculation of the nitrogen blanketing flow rate for distillation columns and absorption towers generally requires determination based on operating conditions, the properties of the materials inside the columns, and the design parameters of the columns. There is no universal experience value that applies to all situations, as different process conditions and equipment designs result in varying nitrogen requirements. However, the following basic steps can be followed to estimate the nitrogen inlet flow rate: 1. **Determine the purpose of nitrogen**: Nitrogen may be used for pressure regulation at the top of the tower, to protect the materials inside the tower from oxidation, or to provide an inert environment for reactions. Identifying the main purpose of nitrogen helps in assessing the required flow rate. 2. **Operating pressure in the tower**: The required nitrogen flow rate is closely related to the operating pressure level in the tower. Higher operating pressures may require more nitrogen to maintain the inert state of the system. 3. **Leakages and emissions**: Consider possible leakage points in the tower system or the volume that needs to be discharged during normal operation (for example, venting gas from the system); these factors all affect the amount of nitrogen that needs to be replenished. 4. **Operational changes**: During start-up, shutdown, or any changes in operation, the nitrogen seal flow rate of the tower may vary. This requires different evaluations for various stages of the operation. 5. **Safety margin**: A certain safety margin is taken into account during the calculation to prevent unexpected situations from occurring in actual operations. 6. **Equipment Instructions/Design Standards**: Refer to the guiding principles or design specifications provided in the tower’s design documents or equipment manuals, as well as historical operation data. 7. **Simulation and calculation tools**: Process simulation software such as ASPEN HYSYS or other chemical process simulation tools is used to simulate actual operating conditions based on the tower design and operating parameters, in order to estimate the required amount of nitrogen blanketing. 8. **On-site measurement data**: If conditions permit, more accurate data can be obtained by actually measuring the nitrogen flow rate during on-site operations. If there is not enough information or simulation tools available, one can initially refer to some general industry experience values; for example, the possible nitrogen consumption rate at the top of the tower is roughly a few to several dozen liters per hour per unit of tower diameter, but this value needs to be adjusted according to the actual conditions. Due to the wide variety of design and operating conditions for distillation and absorption towers, it is best to determine the appropriate nitrogen seal flow rate by taking into account specific process parameters and safety requirements. It is recommended to contact process engineers or equipment suppliers to obtain more detailed and accurate advice. .

Considering a fixed-roof storage tank, the demand for minor breathing, major breathing, and thermal aeration equals the total nitrogen gas consumption. Minor breathing refers to the volatilization of material within the tower, major breathing relates to the flow rate delivered by the pumps upstream, and the demand for thermal aeration is determined in accordance with SH3007-2014