Depressurization System by Coiled Pipes Applied to a High Pressure Process: Experimental Results and Modeling

Background: The use of backpressure regulator valves is widespread in high-pressure processes both at laboratory and pilot plant scales, but being a single step for effluent depressurization, such valves may have some limitations at industrial scale. In an effort to improve the depressurization step, this work studies a system based on the pressure drop of a fluid that circulates through coiled pipes. Method: The equipment, based on three series of variable length coiled pipes, was installed to achieve depressurization of 240 bars in a SCWO pilot plant. Results: The experimental results were compared with those obtained by the modeling carried out using different friction factor correlations from the literature. Conclusion: Among all the correlations tested, the Lockhart–Martinelli correlation showed the best agreement with experimental data. However, it was necessary to obtain an appropriate C parameter to achieve a good agreement with experimental data.