SIM 4900 Green Hydrogen Production

 Model Description

This model represents an 18 MW Proton Exchange Membrane (PEM) electrolysis plant that produces up to 4000 Nm3/h of green hydrogen by splitting demineralised water into hydrogen and oxygen using 16 electrolysis stacks. 

Key Features: 

• PEM Electrolysis Process: Uses electricity to split water into hydrogen and oxygen. A solid polymer electrolyte allows hydrogen ions to pass while keeping the gases separate. 
  • Anode Reaction: 2H2O  →  4H+ + O2 + 4e– 
  • Cathode Reaction: 4H+ + 4e–  →  2H2 

• Electrolysis Stacks: Composed of hundreds of cells with bipolar plates serving as anodes and cathodes, containing fluid channels for water flow. 

• Operation Details: 
  • Water enters through channels, passes through a diffusion layer, and meets the anode catalyst where it splits into oxygen gas and hydrogen ions. 
  • Hydrogen ions pass through the membrane to the cathode, forming hydrogen gas. 
  • Hydrogen side operates at 30 barg; oxygen side at 4 barg. 

• Cooling System: Feed water is circulated through a heat exchanger to cool it before entering the electrolysis stack, this then acts as both a reactant and cooling medium. 

• Separation and Recirculation: 
  • Oxygen-water mixture is separated, with oxygen vented and water recirculated. 
  • Hydrogen-water mixture is cooled and separated, with water recirculated and hydrogen dried through pressure swing adsorption. 

• Purification System: Pressure swing adsorption system with 4 beds of zeolite beads to dry hydrogen for high purity. 

• Electrical Systems: High voltage electricity is stepped down and rectified before being supplied to the electrolysis stacks, with controlled current to manage hydrogen output. 

This model demonstrates efficient green hydrogen production with integrated cooling and purification systems to ensure high-quality output. 

Learning Outcomes

• Understand the principles of hydrogen production using electrolysis. 
• Understand the half-reactions that occur within a PEM electrolysis cell. 
• Understand the electrical potentials in the system and how they affect the performance and efficiency of electrolysis cell. 
• Understand the effect of the voltage, current, and number of cells on hydrogen production and stack efficiency. 
• Understand the ancillary equipment needed to produce high purity hydrogen from a PEM electrolysis system. 
• Understand the principles of pressure swing adsorption. 
• Understand why multiple adsorbers are required and how they operate to produce a continuous supply of hydrogen. 
• Analyse the economics of producing hydrogen in an electrolysis plant