Abstract: An object of the disclosure is to provide a method of efficiently producing a highly-pure vanadium electrolytic solution from a combustion residue that is discharged from facilities such as refineries and power plants and contains uncombusted carbon. The method of producing a vanadium electrolytic solution for redox flow cell (RFB) includes a vanadium eluate generation step of obtaining a vanadium eluate in which vanadium is dissolved. The vanadium is contained in a combustion residue obtained after combustion of a fossil fuel. The method further includes a precipitation step of mixing a sulfide precipitant into the vanadium eluate to precipitate a solid substance of precipitate in a reduction state and a wet oxidation step including a process of adding dilute sulfuric acid to the solid substance separated from the solution to generate a vanadium sulfate solution.

Abstract: The invention relates to an exhaust gas recirculation system as may be used in an engine of an automobile or the like. A housing is provided with an exhaust gas recirculation passage, which may be opened or closed by a valve connected to a diaphragm. The valve includes a rod which is guided by a guide bushing for movement back and forth. A securing protective cover mounted on the housing and a cup-shaped movable protective cover mounted on the diaphragm prevent ingress of a foreign matter between the guide bushing and the valve. An air passage is formed in the movable protective cover. With this construction, the provision of the air passage prevents a negative pressure from prevailing in the movable protective cover, thus preventing a foreign matter such as water or dust which may be deposited on the housing or the like from being drawn into a clearance between the guide bushing and the valve.

Abstract: Fuel is cut off during deceleration and detection of a racing condition. The racing and deceleration detected by the rate of reduction of the rotational speed of the engine. In the case of fuel cut-off during the racing condition, the fuel injection amount after completion of fuel cut-off is increased. A plurality of injections of increased fuel are carried out once every two cycles of the engine.