1 . An electric field-based CO 2 capture apparatus by a hydrate method, wherein the electric field-based CO 2 capture apparatus by a hydrate method comprises a seawater input module, a hydrate former supply module, a hydrate nucleation module, a hydrate enhanced growth module, an external electric field module, a hydrate slurry filtration module and a hydrate block collection module; the seawater input module comprises a seawater supply pipeline, a heat exchanger a and a diverter valve a; incoming seawater is precooled in the heat exchanger a through the seawater supply pipeline and a centrifugal pump a, and then flows through the diverter valve a into two ways according to the set ratio, a first seawater supply pipeline and a second seawater supply pipeline respectively; the first seawater supply pipeline is connected to a spray head at the top of a hydrate nucleation chamber through the valve, and the second seawater supply pipeline is connected to the bottom of the hydrate nucleation chamber; the hydrate former supply module comprises an incoming hydrate former pipeline, a hydrate former recovery pipeline, a hydrate former supply main pipeline, a first hydrate former supply pipeline and a second hydrate former supply pipeline; after the incoming hydrate former enters an heat exchanger b through the incoming hydrate former pipeline for heat transfer, the hydrate former enters the hydrate former supply main pipeline through a mixing valve; and a centrifugal pump b and a diverter valve b are arranged on the hydrate former supply main pipeline; the hydrate former is divided into two ways through the diverter valve b, the first hydrate former supply pipeline and the second hydrate former supply pipeline respectively; the first hydrate former supply pipeline is connected to the top of the hydrate nucleation chamber and replenish the hydrate former so that the pressure reaches the designed pressure; the second water hydrate former pipeline is connected to a hydrate solid-liquid separation chamber; the hydrate solid-liquid separation chamber is connected with the hydrate former recovery pipeline; and the hydrate former flows out of the hydrate solid-liquid separation chamber, passes through a drain valve, a check valve b, a back pressure valve and a diverter valve c in turn, and then flows to the hydrate former recovery pipeline; the recovered hydrate former flows into two ways through the diverter valve c, a hydrate former recapture pipeline and an exhaust gas discharge pipeline respectively; the exhaust gas discharged from the exhaust gas discharge pipeline firstly flows through the heat exchanger b for heat transfer, to precool the incoming hydrate and then discharge; the hydrate former in the hydrate former recapture pipeline is mixed with the precooled hydrate former into the hydrate former supply main pipeline; the hydrate nucleation module comprises the hydrate nucleation chamber; a spray head, a hydrate former inlet, a first pressure sensor and a thermometer are arranged above the hydrate nucleation chamber; a hydrate slurry overflow outlet connected to a first hydrate slurry conveying pipeline is arranged on a side wall of the hydrate nucleation chamber, and hydrate slurry binding agent flows into a spiral pipeline in the hydrate rapid growth chamber through the first hydrate slurry conveying pipeline; a seawater inlet is arranged at the bottom of the hydrate nucleation chamber to receive seawater from the second seawater supply pipeline; a plurality of stirrers are arranged at the bottom of the hydrate nucleation chamber, to make the liquid form uniform hydrate slurry and prevent the hydrate from growing at the bottom; and a discharge valve is arranged at the bottom of the hydrate nucleation chamber; the hydrate enhanced growth module comprises the spiral pipeline, a circulating refrigeration pipeline and a heat exchanger c; the hydrate rapid growth chamber is filled with refrigerant and the spiral pipeline is placed therein; the circulating refrigeration pipeline is connected with the hydrate rapid growth chamber, and the heat exchanger c is installed on the pipeline; and cycle refrigeration of the refrigerant is achieved by the circulating refrigeration pipeline and the heat exchanger c; the external electric field module comprises an electrode plate and a DC power supply; and two electrode plates are located at both ends of the hydrate rapid growth chamber respectively, and provide a DC electric field for an environment in which the hydrate enhanced growth module is located; the hydrate slurry filtration module comprises a hydrate solid-liquid separation chamber, and a cross-section thereof is circular; the hydrate solid-liquid separation chamber has a built-in rotating sieve plate frame, comprising a rotating shaft and a multilayer sieve plate; the rotating shaft is arranged in a cross shape in the hydrate solid-liquid separation chamber which is divided into four partitions; the sieve plate is divided into large aperture and small aperture, the sieve plates of each partition are arranged up and down, and the sieve plate with large aperture is located above the partition; two ends of the sieve plate are respectively connected to the rotating shaft and the hydrate solid-liquid separation chamber; a pressure gauge, a hydrate slurry inlet, a hydrate former nozzle and a hydrate former outlet are respectively arranged above the hydrate separation chamber; the hydrate slurry inlet is connected to the hydrate rapid growth chamber through the second hydrate slurry conveying pipeline, the hydrate former nozzle is connected to the second hydrate former supply pipeline, and the hydrate former outlet is connected to the hydrate former recovery pipeline; the concentrated seawater separated from the hydrate solid-liquid separation chamber passes through a check valve a and flows into the heat exchanger a through a concentrated seawater discharge pipeline for heat transfer, and then is discharged; and the hydrate block collection module comprises a barrier plate, a telescopic plate, a collection plate, a linkage door, a hydrate block removal door and a hydrate block collection box; the hydrate block collection module is connected with a partition of the hydrate solid-liquid separation chamber, the collection plate bears the hydrate blocks in the partition, and the pressure sensor is embedded in the collection plate; the telescopic plate is located on one side of the collection plate, and the barrier plate is located above the telescopic plate, which are linked; the linkage door is located on the other side of the collection plate, and a lower end thereof is connected to the hydrate block collection box through the hydrate block removal door; and when the telescopic plate moves to the other side of the collection plate, the linkage door opens.
2 . The CO 2 capture apparatus by a hydrate method according to claim 1 , wherein the sieve plates have 16 layers, respectively 8 sieve plates with large aperture and 8 sieve plates with small aperture; and two layers of sieve plates are arranged in each partition; and the aperture of the upper sieve plate is larger than that of the lower sieve plate.
3 . The CO 2 capture apparatus by a hydrate method according to claim 1 , wherein the spiral pipeline has multiple pipes, and the pipe diameter increases from top to bottom.