Bronkhorst's distributor, Wagner Mess- und Regeltechnik, helped German R&D companies investigate a new way to store hydrogen: in synthetic, aromatic oil-based heat transfer systems commonly used in bakery systems and other high-temperature applications. Here the heat transfer oil acts as a liquid organic hydrogen carrier, LOHC (Liquid Organic Hydrogen Carrier). High temperatures play a role in this setup Coriolis flow meters in combination with WADose HPLC pumps an important role.
Application requirements
The companies investigate at what pressure the reaction takes place best during charging and discharging. This requires an accurate flow of LOHC and hydrogen to be supplied to the reactor. What is difficult here is the change in viscosity of the LOHC before and after the catalytic reaction. The mass flow meters must be able to cope with these changes in viscosity.
Important subjects
-Be able to dose and pump viscous liquids
-accuracy and high temperatures
flow meters must be able to handle viscosity changes
Process solution
In one setup, the LOHC is heated to achieve the correct viscosity range and brought to a higher pressure by a WADose HPLC pump with heating element. A high-temperature Coriolis flow meter is used with the correct electronics and a control valve to direct the LOHC to the reactor vessel in a measured manner.
In another setup, the dosing of the LOHC at higher viscosities also works excellently with HNP pumps in combination with the Coriolis mass flow meters. The medium does not need to be heated much, because the pump can handle high viscosities well.
Only the flow of the hydrogen that is introduced into the LOHC process is measured. This hydrogen (which leaves the electrolyser in an earlier phase before entering the reactor vessel) is controlled with pressure.
In this application, different Bronkhorst instruments are used for different aspects of the process:
-for applying pressure
-before pumping
-for measuring and controlling media
-to determine the density of the medium
-to measure relevant temperatures
The combination of these devices creates an extremely functional solution.
More information about hydrogen storage research:
The hydrogen is stored in the liquid hydrogen carriers via a catalytic reaction. The liquid now has a low viscosity and looks like water. After hydrogenation, the viscosity has increased and the liquid looks like honey. When charged with hydrogen, this LOHC is flame retardant, making it a safe transport medium for hydrogen to the point of use, after which the hydrogen can be separated from this carrier liquid for pure H2 use.
The charged LOHC can be stored at ambient conditions, which is (another) advantage over gaseous hydrogen.
This charging/discharging is a reversible process; hydrogenation (charging) requires higher pressures, is exothermic and therefore releases energy, while dehydrogenation (discharging) is an endothermic process that requires energy and therefore higher temperatures – both catalytically controlled.
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