System for flue-gas hydrate-based desalination using LNG cold energy

A system for flue-gas hydrate-based desalination using LNG (liquefied natural gas) cold energy, wherein the system for flue-gas hydrate-based desalination comprising

• a refrigerating system,
• a flue-gas capture system,
• a hydrate formation and separation system,
• a hydrate dissociation system,
• a CO2 circulating system, and
• a control system;
• the said refrigerating system comprising an LNG storage tank, gasification chamber and circulating medium, the LNG gasification is endothermic and the gasification amounts of LNG are changed by the opening of a screw valve of the LNG storage tank, the cold energy is transferred to the circulating medium in the gasification chamber, the circulating medium is a closed loop by a water-delivery pump and exchanging heat with seawater and gas respectively before the formation by more heat exchangers, the seawater and gas after the heat exchange are directly to form hydrates;
• the said flue-gas capture system comprising a flue-gas source, heat-exchanged dissociation chamber, first-stage formation chamber and gas separation chamber, the flue-gas source exchanging heat with the hydrates to make them decompose through the heat-exchanged dissociation chamber and then entering the first-stage formation chamber by an air pump and check valve successively after the further heat exchange with the circulating medium, the flue-gas forming CO2 hydrates with the seawater in the first-stage formation chamber, the temperature-hold and pressure-tight residual gas, CO2 hydrates and remnants seawater mixtures going into the gas separation chamber by a multiphase pump, the multiphase pump having a butterfly valve which can automatically open or close according to whether the multiphase pump operates or not, the residual gas in the mixtures is separated out of the gas separation chamber by a second air pump, the left CO2 hydrates and remnants seawater in the gas separation chamber going into a second-stage formation chamber immediately by a second multiphase pump;
• the said hydrate formation and separation system comprising the second-stage formation chamber and a liquid separation chamber, the CO2 hydrates that formed in the first-stage formation chamber and has exhausted residual gas rapidly entering the second-stage formation chamber by a third multiphase pump, the formation rate of CO2 hydrates will increase sharply formed from the new seawater and CO2, both the massive CO2 hydrates and remnants seawater after the formation going into the liquid separation chamber by the third multiphase pump, the liquid separation chamber separating the remnants seawater from the CO2 hydrates and draining the waste water through a gate valve, the remained pure CO2 hydrates going into an exhausting dissociation chamber by a fourth multiphase pump to be decomposed, all the above multiphase pumps are controlled by the control system;
• the said hydrate dissociation system collecting a freshwater from the decomposed CO2 hydrates in the exhausting dissociation chamber and the heat-exchanged dissociation chamber and delivering them into a freshwater storage tank for output use, the dissociation pressure of the exhausting dissociation chamber is controlled by a third air pump and the dissociation temperature of the heat-exchanged dissociation chamber is decided by the flue-gas source;
• the said CO2 circulating system collecting the exhausted CO2 in the exhausting dissociation chamber and the decomposed CO2 in the heat-exchanged dissociation chamber into a CO2 gas tank, the CO2 gas tank providing CO2 gas for the second-stage formation chamber to form hydrates, the redundant CO2 is sequestrated in conventional ways;
• the said control system is used to control the coordinated operation of the whole system for flue-gas hydrate-based desalination using LNG cold energy, the control system controlling the periodic alternate operation of all parts intelligently, it can control and interlock the opening or closing of each valve and the start or stop of each pump as needed, it controlling the temperature of circulating medium by adjusting the LNG amounts into the gasification chamber, it controlling the seawater amounts into the two formation chambers according to the actual production requirement and automatically allotting the seawater amounts for each formation chamber from a sea basin by a second water-delivery pump and two check valves connected to it, it allotting the hydrate amounts for the heat-exchanged dissociation chamber according to the thermal capacity of the flue-gas source and allots other hydrates into the exhausting dissociation chamber.