Method for operating an electrolysis plant, and electrolysis plant

Abstract

Disclosed is a method for operating an electrolysis plant for producing hydrogen and oxygen as product gases, wherein the oxygen product gas, which additionally contains hydrogen as a foreign gas, is fed from an electrolyser to a downstream gas separator, wherein when a predefined limit value for the hydrogen concentration in the oxygen product gas is exceeded, an inert gas (L) is fed to the gas separator such that the hydrogen concentration in the oxygen product gas is lowered. The invention further relates to a corresponding electrolysis plant.

1 . A method for operating an electrolysis system for a generation of hydrogen and oxygen as product gases, in which the oxygen product gas from an electrolyzer, which also contains hydrogen as extraneous gas, is supplied to a gas separator connected downstream, wherein, when a predetermined threshold value for a hydrogen concentration in the oxygen product gas is exceeded, compressed air (L) is supplied to the gas separator, so that in the gas separator a dilution of the hydrogen in the oxygen product gas is brought about by mixing of the gases, lowering the hydrogen concentration in the oxygen product gas. 
     
     
         2 . The method as claimed in  claim 1 , in which air is taken in at atmospheric pressure and compressed to a working pressure and is supplied as compressed air (L) to the gas separator. 
     
     
         3 . The method as claimed in  claim 1 , in which the hydrogen concentration is measured and monitored in-situ in the gas separator. 
     
     
         4 . The method as claimed in  claim 1 , in which compressed air (L) is taken from a pressurized gas vessel and supplied to the gas separator. 
     
     
         5 . The method as claimed in  claim 4 , in which air is taken in at atmospheric pressure and compressed to give compressed air (L), and wherein the gas vessel is loaded with compressed air (L). 
     
     
         6 . The method as claimed in  claim 1 , in which, in a purification step, the compressed air (L) is freed of water-soluble extraneous constituents such as carbon dioxide (CO 2 ) and/or sulfur dioxide (SO 2 ). 
     
     
         7 . The method as claimed in  claim 6 , in which, in the purification step, the compressed air (L) is brought into contact with an adsorbent and/or an absorbent, so that water-soluble extraneous constituents are separated from the compressed air (L) and bound, to obtain high-purity compressed air (L). 
     
     
         8 . The method as claimed in  claim 1 , in which the electrolyzer used is a PEM electrolyzer, wherein a differential pressure between the hydrogen product gas and the oxygen product gas is regulated in such a way that a maximum pressure difference across a proton exchange membrane is not exceeded. 
     
     
         9 . The method as claimed in  claim 1 , in which the generation of hydrogen and oxygen in the electrolyzer is halted as required. 
     
     
         10 . An electrolysis system comprising an electrolyzer for a generation of hydrogen and oxygen as product gases, in which the oxygen product gas also contains hydrogen as extraneous gas, and a compressed air system having a gas vessel for stockpiling of compressed air (L), wherein the electrolyzer is connected to a gas separator via a product stream conduit for the oxygen product gas, and wherein the compressed air system is connected to the gas separator via a feed conduit, so that compressed air (L) is suppliable from the gas vessel to the gas separator as required. 
     
     
         11 . The electrolysis system as claimed in  claim 10 , comprising a valve connected into the feed conduit, in particular a control valve. 
     
     
         12 . The electrolysis system as claimed in  claim 10 , having a purification device for the compressed air (L) connected into the feed conduit, so that extraneous constituents can be separated off from the compressed air (L). 
     
     
         13 . The electrolysis system as claimed in  claim 12 , in which the purification device includes an adsorbent and/or an absorbent, by means of which extraneous constituents from the compressed air (L) are adsorbable and/or absorbable. 
     
     
         14 . The electrolysis system as claimed in  claim 10 , comprising a compressor to which the gas vessel is connected via a connection conduit, so that compressed air is suppliable to the gas vessel as compressed air (L). 
     
     
         15 . The electrolysis system as claimed in  claim 14 , in which the compressor is configured as an oil-lubricated air compressor downstream of which an oil filter is connected. 
     
     
         16 . The electrolysis system as claimed in  claim 14 , in which the compressor is configured as an oil-free air compressor.