Study on deposition characteristics of particulate fouling in U-shaped sewage heat exchange tubes

 This paper analyses the changes of deposition, denudation and thermal resistance of particulate fouling on the heat exchange wall under different sewage flow rate, sewage viscosity, particle concentration and particle size. The results show that the sewage flow rate, the sewage viscosity and the particle concentration have a great influence on the deposition of particle fouling, and when the velocity increases from 0.5 m/s to 1.5 m/s under the condition that other parameters remain unchanged, the deposition rate increases by 2.3 times, the time for denudation to reach stability is shortened to 1/6 of the original, and the fouling thermal resistance decreases by 56%. When the sewage viscosity increases from 0.001 0 Pa·s to 0.003 0 Pa·s, the time for denudation to reach stability increases by 1.27 times, and the fouling thermal resistance increases by 1.25 times. When the particle concentration increases from 400 mg/L to 800 mg/L, the time for denudation to reach stability increases by about 1 time, and the fouling thermal resistance increases by about 1 time. The particle size has little effect on the fouling deposition characteristics, when the particle size increases from 1 μm to 40 μm, the deposition rate increases by only 14%, and the fouling thermal resistance increases only 12.8%. This studys results can be used as a reference for the design, operation and descaling of sewage heat exchangers.