NOVELTY - A device for separating and recovering argon and methane in draining air of synthetic ammonia, comprises a refrigerating case, a raw material draining air pipeline (1), a purifying system which is set with a first molecular sieve absorber MS1 and a second molecular sieve absorber MS2 and is connected with the raw material draining air pipeline (1), a refrigerating system for providing cold material for separating and liquefying, and a rectifying system for separating raw material draining air stage by stage.    USE - The device and the method are useful for separating and recovering argon and methane in draining air of synthetic ammonia (all claimed).    ADVANTAGE - In utilizing the device and the method, the product has high purity and high recovery rate.    DETAILED DESCRIPTION - A device for separating and recovering argon and methane in draining air of synthetic ammonia, comprises a refrigerating case, a raw material draining air pipeline (1), a purifying system which is set with a first molecular sieve absorber MS1 and a second molecular sieve absorber MS2 and is connected with the raw material draining air pipeline (1), a refrigerating system for providing cold material for separating and liquefying, and a rectifying system for separating raw material draining air stage by stage; where the refrigerating system comprises a low pressure circulating nitrogen pressing machine TC1, a middle pressure circulating nitrogen pressing machine TC2, a low temperature pressurizing turbine expansion engine ET2, a high temperature pressurizing turbine expansion engine ET1, a major heat exchanger E1, and a liquefying device E2; the rectifying system comprises a flashing tank S2, a dehydrogenating tower C1 mounted with a first condenser K4 and a first evaporator K1, a denitrifying tower C2 mounted with a second condenser K5 and a second evaporator K2, and a product tower C3 mounted with a third condenser K6 and a third evaporator K3; the second evaporator K2 is connected with the first evaporator K1 which is connected with the first condenser K4 in the dehydrogenating tower C1, the second condenser K5 in the denitrifying tower C2, and the third condenser K6 in the product tower C3; the upper sides of the dehydrogenating tower C1, denitrifying tower C2, and the product tower C3 are connected with the liquefying device E2 by pipelines; the liquefying device E2 is connected with the major heat exchanger E1 by a pipeline; and the major heat exchanger E1 is connected with the middle pressure circulating nitrogen pressing machine TC2 by a pipeline. An INDEPENDENT CLAIM is a method for separating and recovering argon and methane by the device, comprising: (a) entering the raw material draining air into the first molecular sieve absorber MS1 or the second molecular sieve absorber MS2 of the purifying system by the raw material draining air pipeline (1); continuously cooling and liquefying by the liquefying device E2; and saving flow and flashing by the flashing tank S1; (b) separating and flashing most hydrogen by the flashing tank S1 in (a); re-heating the rich hydrogen by the major heat exchanger E1 and discharging out of the refrigerating case; leading the liquid in the bottom part of the flashing tank into the dehydrogenating tower C1; exchanging heat, condensing and evaporating by the dehydrogenating tower C1; obtaining waste hydrogen at top of the dehydrogenating tower C1 and obtaining poor hydrogen liquid at bottom of the dehydrogenating tower C1; (c) re-heating the waste hydrogen obtained from top part of the dehydrogenating tower C1 in (b); delivering the poor hydrogen liquid obtained from bottom part of the dehydrogenating tower C1 into the denitrifying tower C2; (d) re-heating the waste hydrogen obtained from top part of the dehydrogenating tower C1 in (c); heating at 170-180 degrees C in the electric heater HE; removing activated molecular sieve by the first molecular sieve absorber MS1 or the second molecular sieve absorber MS2, and emptying by a muffler SL; delivering the poor hydrogen liquid obtained from bottom part of the dehydrogenating tower C1 into the product tower C3; exchanging heat, condensing and evaporating in the product tower C3; obtaining waste argon at top of the product tower C3, obtaining high-purity liquid argon on the upper side of the product tower C3, and obtaining high-purity liquid methane on the bottom part of the product tower C3; (e) compressing the nitrogen from external side by the low pressure circulating nitrogen pressing machine TC1; dividing into two parts; swelling one part of the compressed nitrogen by the high temperature pressurizing turbine expansion engine ET1, re-heating and discharging out of the refrigerating case, and compressing and circulating in the low pressure circulating nitrogen pressing machine TC1; delivering the other part of nitrogen to the pressurizing end of the low temperature pressurizing turbine expansion engine ET2, increasing pressure, and cooling by the second water cooler WE2; delivering into the major heat exchanger E1, further decreasing temperature and discharging; swelling the low temperature pressurizing turbine expansion engine ET2; delivering into the major liquefying device E2 and the major heat exchanger E1; providing low temperature cold energy; re-heating and discharging out of the cold case and compressing the nitrogen by the low pressure circulating nitrogen pressing machine TC1; and (f) compressing the nitrogen from external side by the middle pressure circulating nitrogen pressing machine TC2; removing from the denitrifying tower C2 and using as heat source of the second evaporator K2; evaporating the poor nitrogen liquid, cooling the liquid at the same time; removing from the dehydrogenating tower C1 and using as heat source of the first evaporator K1; evaporating the poor hydrogen liquid, cooling and liquefying into liquid nitrogen; dividing liquid nitrogen into three parts, providing cold energy from the first, the second and the third condenser K4, K5 and K6; combining the nitrogen which is gasified by the condensers in the dehydrogenating tower C1, denitrifying tower C2 and the product tower C3; delivering to the liquefying device E2 and the major heat exchanger E1; re-heating and discharging out of the cold case; and circulating and compressing in the middle pressure circulating nitrogen pressing machine TC2.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the device for separating and recovering argon and methane in draining air of synthetic ammonia.    Raw material draining air pipeline (1)