Flexible hydrocarbon gas separation process and apparatus
First Claim
1. A flexible hydrocarbon gas separation process that could dehydrate a water-saturated hydrocarbon gas (“
- raw gas”
hereafter) and recover thereof the higher hydrocarbon liquid (“
NGL”
hereafter) with controllable ethane recovery rate ranging from >
95% to <
2% while keeping high recovery rate of all other heavier hydrocarbon components comprises the following steps;
(a) Pre-cooling and pre-dehydrating the raw gas by directly contacting a counter-flowing liquid coolant comprising an aqueous solution of a gas hydrate inhibitor to get a pre-cooled pre-dehydrated gas and a partial NGL condensate;
(b) Deep-cooling and deep-dehydrating the pre-cooled pre-dehydrated gas with a refrigerant from an external refrigerator to get a deep-cooled deep-dehydrated gas and a deep-cooled NGL condensate;
(c) Flowing the NGL condensate into a condensate pre-demethanizer and a flexible condensate deethanizer in tandem to remove all the methane content therein and simultaneously reduce the ethane content therein to any desirable level to get a deep-cooled purified NGL condensate;
(d) Flowing the deep-cooled deep-dehydrated gas into a flexible absorber and contacting the gas with a counter-flowing liquid absorbent (“
lean oil”
hereafter) to get a cold residue gas and a cold rich absorbent (“
rich oil”
hereafter) with a desirable level of ethane content;
(e) Flowing the cold rich oil into a rich oil pre-demethanizer and a flexible rich oil deethanizer in tandem to remove all the methane content therein and simultaneously reduce the ethane content therein to any desirable level to get a purified rich oil;
(f) Depressurizing the purified rich oil and distilling the purified rich oil in a rich oil fractionator to get an NGL vapor and a regenerated lean oil;
(g) Cooling the NGL vapor with a heat transport medium to transport the heat energy from the NGL vapor to the deep-cooled rich oil in the flexible rich oil deethanizer;
(h) Compressing the NGL vapor and mixing the compressed NGL vapor with the deep-cooled purified NGL condensate to get a low-temperature NGL vapor-liquid mixture; and
(i) Liquefying the low-temperature NGL vapor-liquid mixture to get a final NGL product.
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Abstract
The present invention related to a flexible hydrocarbon gas separation process that could dehydrate the water-saturated hydrocarbon gas mixture and recover thereof the required higher hydrocarbons (NGL) therein with a controllable ethane recovery rate (ranging from >95% to <2%) while keeping high recovery rate of all other heavier components. The flexible process comprises the following steps: deep-cooling and dehydrating the raw gas and get the NGL condensate; flowing the deep-dehydrated gas into the flexible absorber to get the rich oil with desirable ethane content; completely demethanizing and partially deethanizing as desired the rich oil and the NGL condensate to get purified rich oil and purified NGL condensate, respectively; separating the NGL vapor from the purified rich oil; cooling and compressing the NGL vapor; mixing the NGL vapor with the purified NGL condensate; and liquefying the mixture to get the final NGL product. The present invention also provides a flexible apparatus with highly efficient components for the flexible process.
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Citations
13 Claims
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1. A flexible hydrocarbon gas separation process that could dehydrate a water-saturated hydrocarbon gas (“
- raw gas”
hereafter) and recover thereof the higher hydrocarbon liquid (“
NGL”
hereafter) with controllable ethane recovery rate ranging from >
95% to <
2% while keeping high recovery rate of all other heavier hydrocarbon components comprises the following steps;(a) Pre-cooling and pre-dehydrating the raw gas by directly contacting a counter-flowing liquid coolant comprising an aqueous solution of a gas hydrate inhibitor to get a pre-cooled pre-dehydrated gas and a partial NGL condensate; (b) Deep-cooling and deep-dehydrating the pre-cooled pre-dehydrated gas with a refrigerant from an external refrigerator to get a deep-cooled deep-dehydrated gas and a deep-cooled NGL condensate; (c) Flowing the NGL condensate into a condensate pre-demethanizer and a flexible condensate deethanizer in tandem to remove all the methane content therein and simultaneously reduce the ethane content therein to any desirable level to get a deep-cooled purified NGL condensate; (d) Flowing the deep-cooled deep-dehydrated gas into a flexible absorber and contacting the gas with a counter-flowing liquid absorbent (“
lean oil”
hereafter) to get a cold residue gas and a cold rich absorbent (“
rich oil”
hereafter) with a desirable level of ethane content;(e) Flowing the cold rich oil into a rich oil pre-demethanizer and a flexible rich oil deethanizer in tandem to remove all the methane content therein and simultaneously reduce the ethane content therein to any desirable level to get a purified rich oil; (f) Depressurizing the purified rich oil and distilling the purified rich oil in a rich oil fractionator to get an NGL vapor and a regenerated lean oil; (g) Cooling the NGL vapor with a heat transport medium to transport the heat energy from the NGL vapor to the deep-cooled rich oil in the flexible rich oil deethanizer; (h) Compressing the NGL vapor and mixing the compressed NGL vapor with the deep-cooled purified NGL condensate to get a low-temperature NGL vapor-liquid mixture; and (i) Liquefying the low-temperature NGL vapor-liquid mixture to get a final NGL product. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- raw gas”
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13. A flexible hydrocarbon gas separation process that could dehydrate a water-saturated raw hydrocarbon gas under high pressure and recover thereof the NGL with controllable ethane recovery rate ranging from >
- 95% to <
2% while keeping high recovery rate (over 90%) of all other heavier hydrocarbon components comprises the following steps;(a) Pre-cooling and pre-dehydrating the raw gas by directly contacting a counter-flowing liquid coolant comprising an aqueous solution of a gas hydrate inhibitor to get a pre-cooled pre-dehydrated gas and a partial NGL condensate; (b) Deep-dehydrating the pre-cooled pre-dehydrated gas with a solid desiccant to get a pre-cooled deep-dehydrated gas; (c) Expanding the pre-cooled deep-dehydrated gas to a lower pressure and temperature to get a deep-cooled deep-dehydrated gas and an NGL condensate; (d) Flowing the NGL condensate and the partial NGL condensate into a condensate pre-demethanizer and a flexible condensate deethanizer in tandem to remove all the methane content therein and simultaneously reduce the ethane content therein to any desirable level to get a deep-cooled purified NGL condensate; (e) Flowing the deep-cooled deep-dehydrated gas into a flexible absorber and contacting the gas with a counter-flowing liquid absorbent (“
lean oil”
hereafter) to get a cold residue gas and a cold rich oil with a desirable level of ethane content;(f) Flowing the cold rich oil into a rich oil pre-demethanizer and a flexible rich oil deethanizer in tandem to remove all the methane content therein and simultaneously reduce the ethane content therein to any desirable level to get a purified rich oil; (g) Depressurizing the purified rich oil and distilling the purified rich oil in a rich oil fractionator to get an NGL vapor and a regenerated lean oil; (h) Cooling the NGL vapor with a heat transport medium to transport the heat energy from the NGL vapor to the deep-cooled rich oil in the flexible rich oil deethanizer; (i) Compressing the NGL vapor and mixing the compressed NGL vapor with the deep-cooled purified NGL condensate to get a low-temperature NGL vapor-liquid mixture; and (j) Liquefying the low-temperature NGL vapor-liquid mixture to get a final NGL product.
- 95% to <
Specification