Performance, material degradation and durability of an ammonia chemical scrubber operated under acidic conditions

The aim of this study was to investigate the tensile strength reduction of four different materials: steel, polypropylene, polyethylene and glass fiber/epoxy (GFRP), under the conditions in a chemical scrubber. . For this reason a pilot -scale scrubber was operated at influent ammonia concentrations between 4000-4200 ppm with gradually decreasing pH. Optimum process performance was achieved at low pH=2.0 and this scrubber liquid used to study the aging of different construction materials, over a six month period.. The outcomes of the study revealed that thermoplastic materials and especially polypropylene are suitable for biogas applications under acidic conditions as their strength and modulus of elasticity remained highly unaffected. For steel specimens, the experimental results showed that failure was due to propagation of a single crack, while the failure of GFRP was caused by multiple microcracks (defects and voids) in the matrix. Finally, the data generated were capable to predict the aging effect on the strength when used to finite element simulations.