Process for the purification of an aqueous stream coming from the fischer-tropsch reaction

A liquid and reactive technology, applied in chemical instruments and methods, preparation of liquid hydrocarbon mixtures, water/sludge/sewage treatment, etc., can solve the problem that organic compounds cannot be completely discharged and/or regenerated

Inactive Publication Date: 2011-02-02

ENI

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AI-Extracted Technical Summary

Problems solved by technology

[0015] However, due to the solubility of organic compounds in water and the inability of organic compounds to be completely discharged an...

Abstract

The present invention relates to a process for the purification of an aqueous stream coming from the Fischer-Tropsch reaction which comprises: feeding the aqueous stream containing organic by products of the reaction to a fractionating distillation column or to a stripping column,- condensation of the vaporized stream leaving the head of the column and the removal of a distillate enriched in the heaviest by-products,- feeding the partially purified aqueous stream leaving the bottom of the distillation column, at the head to one or more sensible contact exchangers,- sending a process gas in countercurrent to the tail of the exchanger at a temperature lower than that of the aqueous stream,- sending the process gas enriched in water and part of the residual organic product leaving the head of the exchanger to the Fischer-Tropsch synthesis plant of hydrocarbons,- sending the purified colder water leaving the exchanger directly to further treatment.

Application Domain

Multistage water/sewage treatmentLiquid hydrocarbon mixture production +3

Technology Topic

ChemistryDistillation +3

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Examples

Experimental program(1)

Example Embodiment

[0061] Example 1

[0062] A pump unit with an impeller immersed in a well with a height of less than 7 m relative to the bottom of the stripping column receives a liquid stream having a pressure equal to about 290 kg/h at a temperature equal to 101.4°C corresponding to 1030 hPa flow. The pump makes the water under pressure regain its 45 bar value at the inlet of the sensitive contact heat exchanger. The methane gas stream is delivered at a flow rate of less than 325 kg/h, a temperature of about 25°C, and a pressure equal to the inlet pressure of water.

[0063] The heat exchanger is manufactured to achieve a performance equal to 5 theoretical thermodynamic steps. In fact, an inlet temperature equal to 105°C for pressurized water corresponds to an outlet temperature equal to 40°C. Remember that there is no insulation.

[0064] Regardless of the fact that the flow rate added to the outgoing gas stream has been reduced by 7 kg/h, the composition data representing the water at the inlet of the heat exchanger shows that at the inlet, the COD is 3100 (relative to the oxidized organic compound 0.225% of the total weight of the feed); at the outlet, the water has COD=2950 (at the outlet, the reduction of organic compounds in the water relative to the total amount is 15%). The gas at the outlet of the heat exchanger has a temperature of 90.5°C and a flow rate of 332 kg/h.

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