Deposition Properties of Sodium Carbonate in Supercritical Water in a Continuous-Flow Tubular Reactor

Abstract:

Supercritical water oxidation (SCWO) has a promising future for treating high concentration and bio-refractory organic wastewaters. However, the reactor plugging problem induced by salt deposition has hindered its extensive commercial application. In this work, we used a continuous-flow experiment plant to systematically examine the influences of the pressure, temperature, running time, initial concentration and flow rate on the deposition properties of Na₂CO₃ under supercritical water conditions. Two parameters including the deposition ratio (R) and the deposition rate (V) were defined to evaluate the deposition extent of Na₂CO₃ in the reactor. The results showed that the pressure and temperature had remarkable influences on the R and V of 1 wt% Na₂CO₃, and their increase would make R and V reduce. The running time had slight effect on the varieties of R and V. Both R and V would rise with the initial Na₂CO₃ concentration increasing. However, V had a reverse change tendency compared with R as the flow rate rose. The R and V of 1 wt% Na₂CO₃ with the flow rate of 0.65 L/h at 550 °C and 25 MPa were higher than 80% and 64 μm/h, respectively. This meant a high reactor plugging risk under the long-time run conditions. Moreover, NaOH was not suitable as the alkali neutralizer of the SCWO process at the low velocity condition in the reactor.

• Periodical: Advanced Materials Research (Volumes 864-867)
• Pages: 1172-1177
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.864-867.1172
• Online since: December 2013
• Authors: Dong Hai Xu*, Shu Zhong Wang, Chuan Bao Huang, Xing Ying Tang
• Keywords: Conductivity, Salt Deposition, Sodium Carbonate, Supercritical Water Oxidation

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