Hydrogen Separation Module Type Hysep® 308

Introduction

The Hysep® 308 has a multi tube design and is especially suited for those who want to test ECN’s thin-film palladium membrane performance at somewhat larger flows and it allows verification of the multi-tube concept. With 0.1 m2 membrane area it represents the first step of scaling-up toward multi-tube systems.

 

Applications

The hydrogen separation module can be used to extract hydrogen from any reformed fuel. This can be an effective means to deliver high quality hydrogen for industrial process gas, for hydrogen fuelling stations or for PEM fuel cells.

 

 

Benefits

 

Quality

  • High hydrogen selectivity, high hydrogen recovery possible

Reliability

  • No moving parts and therefore reliable (passive operation)

Cost efficient

  • Lower Capital Costs. Thin film palladium composite membranes are relatively low cost and allow high hydrogen separation rate per unit membrane area
  • Lower operating cost; dramatic reduction in energy use

Flexibility

  • Expansion of capacity is straightforward; more membrane modules are added.
  • Additional future capacity can easily and cheaply be “designed in” during the first phase of a project
  • Small size

Principle of operation

The hydrogen separation module, type 308, consists of a 316L stainless steel construction, incorporating tubular palladium composite membranes that act as the catalytic/diffusion element.

 

In order to effectively utilize the membranes the hydrogen is brought into contact with the outer surface of the palladium coated ceramic support tube. The thin palladium film acts as a selective barrier, passing only atomic hydrogen through the tube wall, while excluding other gasses. Molecular hydrogen is adsorbed onto the surface where it is dissociated to become atomic hydrogen. The hydrogen gas diffuses through the layer in a direction determined by the pressure gradient. The hydrogen atom recombines on the low pressure side of the membrane with another hydrogen atom and is desorbed as a hydrogen molecule.

 

In addition to the separation of hydrogen, the palladium membranes can drive reactions beyond traditional equilibrium levels because the palladium acts as a catalyst. As an example, the membranes can further drive water gas shift reactions for reformats. This membrane configuration may be operated to maximize hydrogen recovery to extremely high levels (>95%).

 

The Hysep® Technology

ECN has developed the Hysep® technology to enable low cost and reliable hydrogen separation based on thin-film palladium membrane technology. The supported palladium membrane layer in the Hysep® module has a thickness as low as 3-9 µm, a substantial improvement over current commercially available palladium membranes which are based on self-supporting metals foils with a thicknesses of 20-100 µm.

 

To create these membranes ECN has developed the technology to apply a very thin layer of palladium on a ceramic support tube. The assembly combines the excellent hydrogen selectivity of the palladium layer with the robustness of a ceramic support tube. Focus in all aspects of membrane development is on a low-cost end-product. Using thin layers reduces the amount of palladium on a membrane to a minimum. But because these membranes perform better, at the same time less membrane area will be required which will reduce the amount of palladium even further. Cost is crucial in the selection of the support system and manufacturing steps as well. Although the support tube is a high-tech product requiring unique expertise to manufacture, it is based on low-cost ceramic tubes. In producing membranes based on these tubes only production methods are used which enable scale-up to cost-effective high-volume industrial fabrication.

 

Key characteristics of the membranes are the hydrogen flux, selectivity and lifetime. These will depend on the specific process, most importantly on the pressure at which the hydrogen containing mixture is available, gas composition and presence of contaminants. Lifetimes of several thousands of hours have been shown under different conditions and purities which can be reached range from 99.5% to 99.995% depending on the initial composition.

 

The thin palladium layer, combined with the ceramic support tubes on which the Hysep® technology is based, creates a cost-effective and reliable solution to deliver high quality hydrogen.

 

 

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Hysep® 308

Specifications

 

Capacity

  • Standard size: 2.5 – 3.5 kW
  • Hydrogen flow: 2.5 – 3.5 Nm3/h
  • Nominal capacity based on reformate with 51% H2, an inlet pressure of 60 bar and H2 outlet pressure of 3 bar

Quality of hydrogen

  • 99.5% to 99.995%

Process specifications

  • Reformate feed gas inlet pressure: 2-60 bar
  • Operating temperatures: 300- 550°C
  • Process specifications can be adapted to client demands

Mechanical specifications

  • Tubing / cell material: SS 316 (L) and 316Ti
  • Outlet connections: Swagelok SS316 tubing

Design features

  • Placed in self-supported frame with hood
  • Electrical heating with control box
  • Both vacuum and sweep gas (N2 or steam) at H2 outlet possible

Safety features

  • K-type thermo couple in H2 outlet for T control
  • Designed and manufactured according to PED

Dimensions

  • HxWxL: 2.2x0.8x0.8 m

Typical utility specifications

  • N2 for start-up and cooling down
  • Preheated feed

Technical benefits

  • Easy installation and connections
  • English language standard

Additional options

  • Onsite integration
  • Service & support agreements
  • Training