Electrosynthesis system

Abstract

In the case that the concentration of carbon dioxide gas within an exhaust gas has fallen below a predetermined carbon dioxide concentration threshold value in a state in which oxygen gas is being supplied to a synthesizing device, an electrosynthesis system opens a water vapor amount adjustment valve without opening a carbon dioxide amount adjustment valve, and thereby supplies hydrogen gas to the synthesizing device via an electrolysis device.

1 . An electrosynthesis system comprising:
 an electrolysis device configured to subject carbon dioxide gas and water vapor to electrolysis and thereby generate carbon monoxide gas and hydrogen gas;   a synthesizing device configured to use a catalyst to synthesize hydrocarbon gas from the carbon monoxide gas and the hydrogen gas that are discharged from the electrolysis device;   a water vapor amount adjustment valve configured to adjust a flow rate of the water vapor supplied to the electrolysis device;   a carbon dioxide amount adjustment valve configured to adjust a flow rate of the carbon dioxide gas supplied to the electrolysis device;   a carbon dioxide concentration sensor configured to measure a concentration of the carbon dioxide gas within an exhaust gas discharged from the synthesizing device; and   a control device,   wherein the control device comprises one or more processors that execute computer-executable instructions stored in a memory, and in a case that the concentration of the carbon dioxide gas within the exhaust gas has fallen below a predetermined carbon dioxide concentration threshold value in a state in which oxygen gas is being supplied to the synthesizing device, the one or more processors execute the computer-executable instructions to cause the control device to open the water vapor amount adjustment valve without opening the carbon dioxide amount adjustment valve, and thereby supply the hydrogen gas to the synthesizing device via the electrolysis device.   
     
     
         2 . The electrosynthesis system according to  claim 1 , further comprising at least one of a hydrogen concentration sensor configured to measure a concentration of the hydrogen gas within the exhaust gas, or a water vapor concentration sensor configured to measure a concentration of the water vapor within the exhaust gas,
 wherein, in a state in which the oxygen gas is being supplied to the synthesizing device, in a case that the concentration of the hydrogen gas within the exhaust gas exceeds a predetermined hydrogen concentration threshold value, or in a case that the concentration of the water vapor within the exhaust gas falls below a predetermined water vapor concentration threshold value, the one or more processors cause the control device to open the water vapor amount adjustment valve and the carbon dioxide amount adjustment valve and thereby start supplying the carbon dioxide gas and the water vapor to the electrolysis device.   
     
     
         3 . The electrosynthesis system according to  claim 1 , further comprising:
 a hydrocarbon concentration sensor configured to measure a concentration of the hydrocarbon gas within the exhaust gas; and   a switching valve configured to selectively switch whether or not to supply the oxygen gas to the synthesizing device,   wherein, in a case that the concentration of the hydrocarbon gas has fallen below a predetermined hydrocarbon concentration threshold value in a state in which the carbon monoxide gas and the hydrogen gas are being supplied to the synthesizing device, the one or more processors cause the control device to close the water vapor amount adjustment valve and the carbon dioxide amount adjustment valve and thereby stop supplying the carbon dioxide gas and the water vapor to the electrolysis device, and   after supply of the carbon dioxide gas and the water vapor is stopped, the one or more processors cause the control device to control the switching valve and thereby supply the oxygen gas to the synthesizing device.   
     
     
         4 . The electrosynthesis system according to  claim 3 , wherein the one or more processors cause the control device to stop supplying the water vapor after having stopped supplying the carbon dioxide gas. 
     
     
         5 . The electrosynthesis system according to  claim 3 , further comprising a heat exchanger disposed between the electrolysis device and the synthesizing device, and configured to cool a gas supplied from the electrolysis device to the synthesizing device,
 wherein the heat exchanger is configured to adjust a degree of cooling of the gas in accordance with a temperature specified by the control device, and   the one or more processors cause the control device to switch the temperature specified for the heat exchanger depending on a type of the gas.   
     
     
         6 . The electrosynthesis system according to  claim 3 , wherein:
 the electrolysis device is provided in plurality, the synthesizing device is provided in plurality, and the switching valve is provided in plurality;   a first synthesizing device, which is one of the plurality of synthesizing devices, uses the catalyst to synthesize the hydrocarbon gas from the carbon monoxide gas and the hydrogen gas that are discharged from a first electrolysis device, which is one of the plurality of electrolysis devices;   a second synthesizing device, which is another one of the plurality of synthesizing devices, uses the catalyst to synthesize the hydrocarbon gas from the carbon monoxide gas and the hydrogen gas that are discharged from a second electrolysis device, which is another one of the plurality of electrolysis devices;   a first switching valve, which is one of the plurality of switching valves, selectively switches whether or not to supply the oxygen gas, which is generated secondarily by the electrolysis in the first electrolysis device, to the second synthesizing device;   a second switching valve, which is another one of the plurality of switching valves, selectively switches whether or not to supply the oxygen gas, which is generated secondarily by the electrolysis in the second electrolysis device, to the first synthesizing device;   in a case that the concentration of the hydrocarbon gas within the exhaust gas discharged from the first synthesizing device has fallen below a predetermined hydrocarbon concentration threshold value in a state in which the carbon monoxide gas and the hydrogen gas are being supplied to the first synthesizing device, the one or more processors cause the control device to control the second switching valve and thereby supply the oxygen gas to the first synthesizing device; and   in a case that the concentration of the hydrocarbon gas within the exhaust gas discharged from the second synthesizing device has fallen below a predetermined hydrocarbon concentration threshold value in a state in which the carbon monoxide gas and the hydrogen gas are being supplied to the second synthesizing device, the one or more processors cause the control device to control the first switching valve and thereby supply the oxygen gas to the second synthesizing device.