NOVELTY - The system (10) has a control apparatus (34) that supplies vapor heated by a heater to one of the solenoid valves based on an instruction. The vapor is ejected in pipes more nearly than vapor supply tubes while opening/closing vapor valve and closing/opening vapor valve respectively to generate superheated steam. The direction of the circulating flow of superheated steam generated by a heat-energy generator is switched. The wire filters are installed in the opening of pipes and installation of filters in the pipes is controlled by control apparatus.    USE - Gas recovery system of oil collecting system (claimed), for recovering gas such as methane and ethane from underground surface and sea surface.    ADVANTAGE - The clogging of intake pipe is prevented so that maintenance of the heat-energy generator is simplified and gas recovery from gas-hydrate layer and oil recovery from oil-sand layer are performed stably and continuously for a long time.    DETAILED DESCRIPTION - The system includes a steam generator, a feed pipe which supplies water, and a heater installed in the feed pipe for heating the water supplied by the feed pipe. The vapor supply tubes are inclined in the direction of the opening of the pipes. The valves are installed in the supply tubes. The heat-energy generator is positioned at a predetermined interval with respect to the axis line of gas recovery system. The valves are operated with a vapor pressure generated in the steam generator. An INDEPENDENT CLAIM is included for oil collecting system that includes a heat-energy generator positioned in vicinity of oil sand layer. The steam generator heats water and generates vapor and a superheated steam generation apparatus heats the vapor to generate a superheated steam which is circulated in the oil sand layer as high-speed airflow. The pipes recirculate the superheated steam and eject the superheated steam towards the oil-sand layer. The oil separated with the heat energy of the superheated steam is circulated and provided as high-speed airflow towards the oil sand layer. The control apparatus switches circulation of superheated steam and oil with respect to the sand layer and controls ejecting direction of the superheated steam.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the gas recovery system.    Gas recovery system (10)    Outer cylinder (12)    Inner cylinder (14)    Gas recovery pipe (16)    Control apparatus (34)