Pyrolysis Characteristics of Waste Salt Organic Impurities in Solar Reactors

To effectively remove organic impurities from waste salt for better waste salt recycling and environmental protection, a pyrolysis reactor model based on a parabolic trough concentrator and a tubular reactor was established in this paper. The effects of reflector depth, focal length, and reactor outer diameter on the energy distribution and the organics pyrolysis characteristics were investigated through photothermal coupling. The results show that as the reflector depth increased from 100 mm to 1000 mm, the average concentration ratio of the concentrator increased by 7.34 while the optical efficiency decreased by 0.52%; both the maximum temperature Tmax and minimum temperature Tmin of the reactor increased, with a temperature difference ΔT of the reactor about 100 K; the pyrolysis reaction time was shortened, and the thermal efficiency of the system increased by about 10.71%. As the focal length increased from 100 mm to 1 000 mm, the heat flow density became more concentrated, resulting in a 21.03 increase in the maximum concentration ratio and a 0.53% decrease in optical efficiency; the Tmin did not change significantly, but the Tmax and ΔT exhibited a linear increase, with the ΔT increasing from 31.45 K to 222.56 K; the system reaction rate and thermal efficiency increased. As the reactor outer diameter increased from 14 mm to 104 mm, the heat flow density decreased, the Rave decreased from 34.75 to 4.71, and the optical efficiency increased by 0.53%. The Tmax and Tmin exhibited a decreasing trend, while ΔT increased from 52.13 K to 114.32 K. The reaction rate and thermal efficiency decreased, but the pyrolysis time of per unit volume waste salt decreased from 5.26 s•cm-3 to 1.29 s•cm-3. The study results presented in this paper are significant for the parameter design and optimization of solar waste salt pyrolysis reactor. © 2025 Xi'an Jiaotong University. All rights reserved.