Inherently safe oxygen/hydrocarbon gas mixer
AssigneeNOVA Chemicals (International) S.A.
InventorsVasily Simanzhenkov, Shahin Goodarznia, Kamal Elias Serhal, Bolaji Olayiwola, Eric Clavelle
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Abstract
Provided herein is a gas mixer for the safe mixing of a hydrocarbon containing gas with a gaseous oxidant. The gas mixer and method for mixing described includes a closed mixing vessel where bubbles of gas injected at the bottom of the vessel are mixed during their rise to the top of the vessel, forming a homogeneous mixture that can safely be removed. This simple design and method allows for safe mixing of gases and is applicable to catalytic oxidative processes such as oxidative dehydrogenation of paraffins where there is a risk of thermal runaway of reactions.
Claims19
A gas mixer for mixing a hydrocarbon containing gas with a gaseous oxidant, comprising:
- i) a closed mixing vessel having a top end, a bottom end, and flooded with a non-flammable liquid;
- ii) a liquid supply nozzle for introducing a non-flammable liquid into the closed mixing vessel in close proximity to the top end;
- iii) a drain connection for removing non-flammable liquid from the closed mixing vessel located in close proximity to the lowest point of the bottom end;
- iv) at least one hydrocarbon containing gas supply nozzle for introducing hydrocarbon containing gas into the closed mixing vessel near the bottom end;
- v) at least one gaseous oxidant supply nozzle for introducing gaseous oxidant into the closed mixing vessel near the bottom end;
- vi) at least one means within the closed mixing vessel for internal mixing of introduced hydrocarbon containing gas with introduced gaseous oxidant;
- and
- vii) a mixed gas outlet located in close proximity to the uppermost point of the top end;
- wherein the level of non-flammable liquid within the closed mixing vessel is at a height sufficient to allow mixing of the introduced hydrocarbon containing gas and the gaseous oxidant before reaching the top end such that bubbles of gas exiting the non-flammable liquid comprise a mixture of hydrocarbon containing gas and gaseous oxidant that is outside the flammability limit.
A method of mixing a hydrocarbon containing gas and a gaseous oxidant within a closed mixing vessel flooded with a non-flammable liquid and having a bottom end, a top end, and internal mixing means, with the resulting gaseous mixture being homogenous and comprising a ratio of hydrocarbon containing gas to gaseous oxidant that is outside the flammability envelope, the method comprising:
- i) introducing a hydrocarbon containing gas into close proximity to the bottom end of the closed mixing vessel;
- ii) introducing a gaseous oxidant, simultaneously with the hydrocarbon containing gas, in close proximity to the bottom end of the closed mixing vessel;
- and
- iii) recovering a homogenous gaseous mixture of hydrocarbon containing gas and gaseous oxidant in close proximity to the top end of the closed mixing vessel;
- wherein the level of non-flammable liquid together with the internal mixing means provide sufficient residence time and promote interactions between bubbles of hydrocarbon containing gas and gaseous oxidant such that the gas exiting the non-flammable liquid comprises a mixture of hydrocarbon containing gas and gaseous oxidant that is outside the flammability limit.
A process for the oxidative dehydrogenation of ethane to ethylene, the process comprising:
- i) mixing an ethane containing gas and a gaseous oxidant in a closed mixing vessel;
- ii) passing the mixture from i) through a heat exchanger to raise the temperature to at least 250° C.;
- iii) introducing the mixture from ii) into an ODH reactor containing an ODH catalyst, giving a product stream containing unreacted ethane, CO, C2H4, CO2, H2O, CH3COOH, minimal hydrocarbons, and possibly O2;
- iv) directing product stream from iii) through a quench tower to remove H2O and CH3COOH;
- v) directing product stream from iv) through at least one amine wash to remove CO2;
- and
- vi) directing product stream from v) through a demethanizer (distillation tower) to separate from the product stream.
Dependencies are inferred from the claim text.