Table of Contents
Gas treating in refineries involves removing impurities from natural gas or other hydrocarbon streams. Absorbers and strippers are essential equipment used in this process to ensure the purity and quality of the final product. Proper design and calculation of these units are crucial for efficiency and safety.
Design Principles of Absorbers
Absorbers are vessels where impurities are absorbed from the gas into a liquid solvent. The design focuses on maximizing contact between the gas and liquid to enhance mass transfer. Key parameters include flow rates, temperature, pressure, and solvent properties.
The height and diameter of the absorber are determined based on the required capacity and mass transfer efficiency. Proper distribution of the liquid and gas flow ensures uniform contact and prevents channeling.
Calculating Absorber Performance
Performance calculations involve determining the absorption efficiency and the solvent flow rate needed to meet impurity removal targets. The use of equilibrium data and mass transfer coefficients helps in designing effective absorbers.
Design equations, such as the McCabe-Thiele method or the use of operating line diagrams, assist in estimating the number of theoretical stages required for desired separation.
Design and Calculation of Strippers
Strippers are used to regenerate the solvent by removing absorbed impurities. They operate at different conditions than absorbers, often at higher temperatures to facilitate stripping.
The design involves selecting appropriate column height, diameter, and tray or packing type. Calculations focus on achieving sufficient stripping efficiency while minimizing energy consumption.
Key parameters include vapor and liquid flow rates, temperature profiles, and the equilibrium data for the impurities. Proper design ensures the solvent is effectively regenerated for reuse.
Summary
Designing absorbers and strippers requires understanding of mass transfer principles and process conditions. Accurate calculations ensure effective impurity removal, operational efficiency, and safety in refinery gas treating units.