Hydrogenators

Hydrogenators

Hydrogenation is a very common class of reaction in an industrial setting.  It forms a large chunk of our autoclave sales business at Amar. Below we show some typical industrial hydrogenations (from the book by Mouljin & Sharma on Fine Chemicals)

This is just an illustration to show the huge varieties of hydrogenations that are possible. From a process design perspective, it is crucial to choose the right reactor for your hydrogenation projects. It is impossible to provide comprehensive advice in a single blog post but here are some tips:

• For smaller volumes of production, batch hydrogenation is usually a common choice. Batch hydrgogenators are extremely versatile.

Most multipurpose pharma and specialty plants have a dedicated section devoted to hydrogenators. As volumes of production increase, it is a wise idea to consider flow mode designs such as trickle beds, bubble columns, loop reactors, etc.

• Safety is paramount for any project involving hydrogenation. Do not skip a Hazop. Remember H2 is a gas that is extremely flammable under a wide range of conditions. H2 flames can be impossible to see with the naked eye.
• Seals and gaskets: Hydrogen has very low MW and extremely high diffusivity. It can leak out from situations that other gases will not. Consider your sealing devices carefully. The industry has progressed from stuffing boxes to double mechanical seals but our strong advice is to select a magnetic drive whenever possible. At Amar, we manufacture our own magnetic drives

• Spargers: Hydrogenations are Gas Liquid reactions (often with the assistance of a solid catalyst). These Gas-liquid reactions are often mass transfer limited. Reaction speeds require large interfacial areas which can be provided by small bubble sizes. Sparger designs are crucial for this. Modern sintered metal spargers are often a great choice for small bubble sizes.
• Gas reinduction impeller designs: Typically hydrogen has low solubility and reaction times are long enough that H2 will not react completely in one pass up the reactor. This makes the entrainment of H2 critical. A good reinduction impeller will make a huge difference. Amar makes a proprietary design of a hollow shaft impeller.

The next blog post in this series will continue to provide more tips on Hydrogenators. Stay tuned! Please sign up on our email list to be notified of the next blog post.