Process for Helium Recovery
Publication Date: 2005-Apr-19
The IP.com Prior Art Database
Process for Helium recovery
Most of the helium produced worldwide is from natural gas containing more than 2 % Helium. The separation of Helium is achieved using membranes or cryogenics. For lower concentrations natural gas fields can still be attractive if the natural gas is liquefied. During this process the Helium accumulates in the gaseous phase, which is purged. In this stream the concentration of helium is such that it can be economically separated from the hydrocarbon containing gas.
The proposed solution allows recovery of helium from natural gas which is chemically converted to transportable liquids. This enlarges the sources which can be exploited for Helium production which at present are diminishing. The main problem when separating Helium from these processes is that the natural gas is typically converted to syngas and the separation of Hydrogen/CO and Helium is far more complicated than the separation of Hydrocarbons and Helium.
The chemical conversion of natural gas to transportable liquids like methanol, its derivates or hydrocarbons with a carbon number > 3, is generally characterised by a syngas stage and a conversion step using a recycle to increase the overall carbon and hydrogen efficiency.
Application 1 : Fischer Tropsch reaction
The conversion of natural gas to liquid hydrocarbons (GTL) with a carbon number > 3 is commonly using a syngas (stream 11) process followed by a Fischer-Tropsch Synthesis section (
box3). In most cases, syngas (stream 11) is produced by reaction of pure oxygen (stream 10) , steam (stream 9) and natural gases (stream 8) in auto thermal reformer or POX (
The off gasses from the Fischer –Tropsch synthesis section are taken and treated to recover, amongst possibly others, the Hydrogen / CO (stream 14) which can be recycled to the process. This separation can be performed with adsorption, cryogenics or membranes (box 5 ).
When recycling the Hydrogen / CO leaving the Fischer-Tropsch synthesis section, the Heliumwhich was present in the natural gas used for the syngas production is accumulated.
A part of the Hydrogen / CO stream fraction (stream 14) can be treated with a purification step (box 6 : adsorption, cryogenics or membranes). Hydrogen is separated from the other components like CO and traces of Methane, and the Helium will leave the process with this hydrogen stream (stream 15).
Having obtained a Hydrogen / Helium stream (stream 15) , the recovery of helium can be made by a oxidation stage (direct burning or catalytic combustion : box 7) of the Hydrogen using pure oxygen (purity 99.5 % - 0.5 % Argon) (stream 10). After this step, the produced water (stream 18) is separated with a liquid separation and the resulting gas is dried (box 8). This process will provide the Helium product with a purity of 97 % (stream 17).
- If oxygen with a better purity is used, the produced Helium stream purity can be higher.
- The separation 1 and 2 can be made with the same unity (for ex...