Abstract: In a diesel engine which includes an air intake system, an exhaust system, and an exhaust gas recirculation passage which recirculates part of the exhaust gases produced by the engine from the exhaust system to the air intake system, a control system for the recirculation of exhaust gases and the flow of intake air, having an intake air flow control valve mounted in the air intake passage, and a recirculated exhaust gas flow control valve, mounted in the exhaust gas recirculation passage, these two control valves being so coupled together that, as one of them opens progressively, the other closes progressively, and vice versa, so that exhaust gas recirculation ratio alters in substantially direct proportion to the amount of opening of the exhaust gas recirculation flow control valve.

Abstract: A process is provided for recovering a solvent vapor from a mixed gas of the solvent vapor and air. From a vessel storing a mixed gas of the solvent vapor and air, the mixed gas is passed through a compressor to be compressed to a low degree, the resultant compressed mixed gas is introduced to a first absorption column, where said compressed mixed gas is brought into contact with a first absorbent to absorb and recover a greater part of the solvent vapor. A gas coming out from the first absorption column is introduced to a second absorption column, where said gas is brought into contact with a second absorbent.