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US 7,019,038 B2Granted
Recycle of low boiling point products to a Fischer-Tropsch reactor
AssigneeConocoPhillips Company
InventorsRafael L. Espinoza, Harold A. Wright, Jianping Zhang
Life of this patent
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Abstract
Methods for reducing the average molecular weight of liquid hydrocarbons in a Fischer-Tropsch reactor are disclosed. The preferred embodiments of the present invention are characterized by feeding a hydrocarbon stream, which lowers the average molecular weight of the hydrocarbon liquids inside the reactor, and more preferably by recycling a portion of low-molecular weight hydrocarbon products back into the reactor. Lowering the molecular weight of the hydrocarbon liquids inside the reactor increases the mass transfer and solubility, and diffusivity of the reactants in the hydrocarbons present in the slurry.
Claims44
A method for increasing the mass transfer of a reactant gas component into a liquid product comprising:
- feeding a reactant gas to a catalytic reactor;
- converting at least a portion of the reactant gas on a synthesis catalyst to generate in the catalytic reactor a liquid product having a product average molecular weight;
- withdrawing from the catalytic reactor a liquid outlet stream comprising at least a portion of the liquid product, the liquid outlet stream having an outlet average molecular weight lower than the product average molecular weight;
- and
- feeding to the catalytic reactor a hydrocarbon feedstream with a feed average molecular weight of less than the outlet average molecular weight, such that the difference between the product average molecular weight and the outlet average molecular weight favors a mass transfer increase of at least one component of the reactant gas into the liquid product inside the catalytic reactor, wherein the ratio of the hydrocarbon feedstream flow rate over the liquid outlet stream flow rate is between 0.14 to 0.95.
2 more elements
A method for increasing the mass transfer of a reactant gas component into a liquid product comprising:
- feeding a reactant gas to a catalytic reactor;
- converting at least a portion of the reactant gas on a synthesis catalyst to generate a liquid product having a product average molecular weight;
- withdrawing from the catalytic reactor a liquid outlet stream comprising at least a portion of the liquid product, the liquid outlet stream having an outlet average molecular weight lower than the product average molecular weight;
- separating the liquid outlet stream into at least a light stream and a heavy stream;
- and
- feeding a recycling stream comprising at least a portion of the light stream to the catalytic reactor at a recycle ratio so as to maintain the outlet molecular weight, such that the difference between the product average molecular weight and the outlet average molecular weight favors a mass transfer increase of at least one component of the reactant gas into the liquid product in the catalytic reactor, wherein the ratio of the recycling stream flow rate over the liquid outlet stream flow rate is between 0.14 and 0.95.
3 more elements
A method for increasing the solubility of synthesis gas into a liquid product, comprising:
- feeding synthesis gas to a synthesis reactor;
- converting at least a portion of the synthesis gas to generate a liquid product with a product average molecular weight;
- withdrawing from the synthesis reactor a liquid outlet stream comprising at least a portion of the liquid product, the liquid stream having an outlet average molecular weight lower than the product average molecular weight;
- separating the liquid stream into at least a light stream and a heavy stream;
- and
- feeding a recycling stream comprising at least a portion of the light stream to the synthesis reactor, wherein the recycling stream has an average molecular weight lower than the outlet average molecular weight, and wherein the ratio of recycling stream flow rate over the liquid stream flow rate is such as to maintain the outlet average molecular weight within a range selected to increase the solubility of at least one component of the synthesis gas into the liquid product in the synthesis reactor, wherein the ratio of the recycling stream flow rate over the liquid outlet stream flow rate is between 0.14 and 0.95.
3 more elements
A process for producing hydrocarbons from synthesis gas, comprising:
- feeding a reactant gas comprising H2 and CO to a hydrocarbon synthesis reactor;
- feeding a hydrocarbon feedstream with an average molecular weight between 150 and 300;
- converting at least a portion of the reactant gas on a hydrocarbon synthesis catalyst to generate a hydrocarbon product stream of an average molecular weight of more than 300;
- combining the hydrocarbon product stream and the hydrocarbon feedstream within the hydrocarbon synthesis reactor to generate a reactor outlet stream, wherein the flow rate of hydrocarbon feedstream and the rate of conversion are such that the reactor outlet stream has an average molecular weight between 100–350.
1 more element
A method for producing hydrocarbons comprising:
- providing a slurry comprising a hydrocarbon liquid component inside a catalytic reactor;
- removing at least a portion of the slurry comprising hydrocarbons from the catalytic reactor;
- separating the at least said portion of the slurry into a first stream having an average hydrocarbon molecular weight higher than the average hydrocarbon molecular weight of the slurry hydrocarbon liquid component remaining in the catalytic reactor and a second stream having an average hydrocarbon molecular weight lower than the average hydrocarbon molecular weight of the slurry hydrocarbon liquid component remaining in the reactor;
- and
- returning at least a portion of the second stream to the reactor so as to reduce the molecular weight of the average hydrocarbon molecular weight of the slurry hydrocarbon liquid component in the reactor, wherein the ratio of the flow rate of the returned portion of the second stream to the rate of the liquid withdrawal in the slurry is between 0.14 and 0.95.
2 more elements
A method for decreasing the average molecular weight of a liquid component in a reactor, the method comprising:
- contacting a gaseous reactant with a catalyst in a reactor to produce an intermediate component having an average molecular weight MWP;
- removing a liquid outlet stream from the reactor, the liquid outlet stream comprising at least a portion of the intermediate component and having an average molecular weight MWW;
- separating the liquid outlet stream into a recycle stream and a products stream, the recycle stream having an average molecular weight MWR;
- and
- feeding at least a portion of the recycle stream into the reactor;
- wherein MWR<MWW l <MWP;
- wherein the ratio of the recycle stream flow rate over the liquid outlet stream flow rate is between 0.14 and 0.95.
4 more elements
Dependencies are inferred from the claim text.