Hydrogenation is the chemical addition of hydrogen to a hydrocarbon in the presence of a catalyst, a severe form of hydrogen treating is added to a molecule that is unsaturated with respect to hydrogen. In either case, the resulting molecules are highly stable.
In presence of a suitable catalyst such as nickel, gaseous hydrogen adds to the double bond of unsaturated fatty acid and transforming them to the corresponding saturated acid and reducing their degree of unsaturation.
The use of hydrogen requires precautions against creating an explosive mix of hydrogen and air. Typically, a hydrogenation vessel undergoes a pressure test followed by several nitrogen purges before hydrogen is introduced. Similarly, at the end of the reaction process, the vessel is purged with nitrogen in order to leave it in a safe condition. Normally, a hardwired safety system confirms the pressure test and nitrogen purge phases before allowing the hydrogen line to be opened.
Hydrogenation requires high pressures to be maintained in the reaction vessel - giving problems over maintaining seals around agitators which in some cases require additional seal integrity checks or upgrades to incorporate magnetic coupling systems.
Hydrogenation also tends to be a highly exothermic reaction, resulting in demanding temperature control requirements.
The process is used to increase the solid (crystalline fat) content of edible fats and oils & improve their resistivity to thermal and atmospheric oxidation. Hydrogenation rate is governed by temperature, the type of oil being hardened, catalyst activity, selectivity, catalyst concentration, the goal of hydrogenation are to achieve the highest possible activity consist will control of selectivity which we use least possible amount of catalyst.
Such goals are met only to ensuring the following:
- The cleanest possible feed (no soap phosphatides, sulphur compound).
- Hydrogen gas as far as possible (Purity 99.99%)
- Clean airtight hydrogenation vessel
- Catalyst control
- Excellent control of the catalyst filtration process
A control system must therefore provide flexibility in the way in which accurate and repeatable control of the hydrogenation environment is achieved and will include the following features:
- Sequential control for vessel pressure testing, purging and hydrogen addition
- Precise loop control for temperature and pressure
- Secure collection of on-line data from the hydrogenation process for analysis and evidence
- Local operator display with clear graphics and controlled access to parameters