Investigation on a high gravity device for reduction of NOx emission from marine diesel engines.

High gravity technology, as a process intensification technology, has demonstrated the great advantages in the field of gas purification on account of its excellent mass transfer efficiency and energy-efficient, but it is rarely applied in the field of nitrogen oxides (NOx) purification of marine diesel engine exhaust. In this paper, a high-gravity bowl-shaped-disk rotating bed (HBRB) without catalytic was designed for diesel exhaust after-treatment. A diesel oxidation catalyst (DOC) was installed in the front of the HBRB to regenerate more nitrogen dioxide (NO2) easily reduced by urea. A bench test of a 6-cylinder marine diesel engine with the HBRB was carried out. The effects of the HBRB speeds, urea concentrations, and engine operating conditions on NOx purification efficiency in engine exhaust were experimentally investigated. The experimental result indicates that the maximum NOx removal efficiency of the HBRB can reach 69.1%. The improvement of the NOx removal efficiency is not obvious at the HBRB speed of over 1500 r/min. The pre-oxidation degree of nitric oxide (NO) and urea concentration largely affect the NOx removal efficiency. The HBRB has great potential in marine diesel engine exhaust denitration.