Combined acid gas removal and water filtration system
The combined acid gas removal and water filtration system ( 10 ) removes sour gases, such as hydrogen sulfide (H2S) and carbon dioxide (CO2), from an input gaseous hydrocarbon stream (FG), as well as producing purified water (TW). The acid gas removal system ( 10 ) has a contactor ( 12 ) for contacting the input gaseous stream (FG) with an absorption liquid solvent (ALS), and a stripper ( 24 ) for recycling the absorption liquid solvent (ALS) and removing acidic gases (AG) therefrom. A first heat exchanger ( 22 ) heats used absorption liquid solvent (UALS) output from the contactor ( 12 ) prior to injection into the stripper ( 24 ). A second heat exchanger ( 26 ) cools recycled absorption liquid solvent (RALS) using a refrigerant (R) before injection back into the contactor ( 12 ). The refrigerant (R) is coupled with an absorber ( 84 ), which receives a dilute ethanolic draw solution (DDS) from a forward osmosis filtration system ( 72 ), producing purified water (TW).
1. A combined acid gas removal and water filtration system, comprising:
an absorption liquid solvent capable of removing acidic gases from gaseous hydrocarbons;
a refrigerant;
a contactor having:
a gas inlet adapted for receiving a stream of gaseous hydrocarbons;
a gas outlet adapted for providing an outlet for the gaseous hydrocarbons after removal of acidic gases therefrom, the gaseous hydrocarbons being contacted by the absorption liquid solvent and the acidic gases being removed therefrom by absorption into the absorption liquid solvent inside the contactor;
an absorption liquid inlet for introducing the absorption liquid solvent into the contactor; and
an absorption liquid outlet for removing used absorption liquid solvent having the acidic gases absorbed therein from the contactor;
a first heat exchanger in fluid communication with the contactor, the first heat exchanger being configured for receiving the used absorption liquid solvent and heating the used absorption liquid solvent to output heated solvent;
a stripper in fluid communication with the first heat exchanger, the stripper being configured for receiving the heated solvent and separating the heated solvent into an acidic gas waste stream and recycled absorption liquid solvent, the recycled absorption liquid solvent providing a heat source to the first heat exchanger for heating the used absorption liquid solvent;
a second heat exchanger in fluid communication with the first heat exchanger, the second heat exchanger being configured for receiving the recycled absorption liquid solvent and for receiving the refrigerant from a refrigerant tank for cooling the recycled absorption liquid solvent to form at least a portion of the absorption liquid solvent received by the contactor through the absorption liquid inlet thereof;
a draw solution comprising ethanol;
a forward osmosis filtration system having a feed side, a draw side, and a semipermeable membrane disposed between the feed side and the draw side, the feed side having an input adapted for connection to a source of brine for filling the feed side with brine, the draw side having an input connected to the draw solution for filling the draw side with the draw solution; and
an absorber tank configured for receiving the refrigerant from the second heat exchanger and for receiving the draw solution diluted by water passing from the brine through the semipermeable membrane from the draw side of the forward osmosis filtration system by osmotic pressure, such that the refrigerant absorbs ethanol from the dilute draw solution, producing pure water and a mixture of ethanol and the refrigerant, the mixture of ethanol and the refrigerant being returned to the refrigerant tank and a portion of the pure water being received by the contactor through a wash water inlet thereof.
2. The combined acid gas removal and water filtration system as recited in claim 1 , wherein the first heat exchanger comprises a plate-plate heat exchanger.
3. The combined acid gas removal and water filtration system as recited in claim 2 , wherein the second heat exchanger comprises a plate-plate heat exchanger.
4. The combined acid gas removal and water filtration system as recited in claim 1 , wherein said absorption liquid solvent comprises methyl diethanolamine (MDEA) and a piperazine (PZ) additive.
5. The combined acid gas removal and water filtration system as recited in claim 1 , wherein the refrigerant is n-pentane.
6. The combined acid gas removal and water filtration system as recited in claim 1 , further comprising a reboiler connected to the stripper for heating the heated solvent for stripping acidic gases from the heated solvent in the stripper.
7. The combined acid gas removal and water filtration system as recited in claim 1 , further comprising a reflux drum in fluid communication with the first heat exchanger for receiving the acidic gas waste stream from the first heat exchanger for reflux thereof.
8. The combined acid gas removal and water filtration system as recited in claim 1 , further comprising a knock out drum connected to the gas inlet of the contactor for removing solid and liquid impurities from the stream of gaseous hydrocarbons.
9. The combined acid gas removal and water filtration system as recited in claim 8 , further comprising a draw solution tank containing aqueous ethanol solution.
10. The combined acid gas removal and water filtration system as recited in claim 9 , wherein a further portion of the pure water is recycled through the draw solution tank.
11. The combined acid gas removal and water filtration system as recited in claim 10 , wherein water removed from the stream of gaseous hydrocarbons by the knock out drum is mixed with the brine being fed into the feed side of the forward osmosis filtration system.
12. A combined acid gas removal and water filtration system, comprising:
an absorption liquid solvent capable of removing acidic gases from gaseous hydrocarbons, the absorption liquid solvent being methyl diethanolamine (MDEA) and a piperazine (PZ) additive;
a refrigerant and a refrigerant tank, the refrigerant being stored in the refrigerant tank, the refrigerant being n-pentane;
a draw solution and a draw solution tank, the draw solution being stored in the draw solution tank, the draw solution being an aqueous solution of ethanol;
a contactor having:
a gas inlet adapted for receiving a stream of crude natural gas;
a gas outlet adapted for providing an outlet for the natural gas after removal of acidic gases therefrom, the crude natural gas being contacted by the absorption liquid solvent and the acidic gases being removed therefrom by absorption into the absorption liquid solvent inside the contactor;
an absorption liquid inlet for introducing the absorption liquid solvent into the contactor; and
an absorption liquid outlet for removing from the contactor used absorption liquid solvent having the acidic gases absorbed therein;
a first heat exchanger in fluid communication with the contactor, the first heat exchanger being configured for receiving the used absorption liquid solvent from the absorption liquid outlet and heating the used absorption liquid solvent to output heated solvent;
a stripper in fluid communication with the first heat exchanger, the stripper being configured for receiving the heated solvent from the first heat exchanger and stripping the acidic gases from the heated solvent using steam to produce an acidic gas waste stream and recycled absorption liquid solvent, the recycled absorption liquid solvent being coupled to the first heat exchanger to provide a heat source to the first heat exchanger for heating the used absorption liquid solvent;
a second heat exchanger in fluid communication with the first heat exchanger, the second heat exchanger being configured for receiving the recycled absorption liquid solvent from the first heat exchanger and for receiving the refrigerant from the refrigerant tank for cooling the recycled absorption liquid solvent to form at least a portion of the absorption liquid solvent received by the contactor through the absorption liquid inlet thereof;
a forward osmosis filtration unit having a feed side, a draw side, and a semipermeable membrane disposed between the feed side and the draw side, the feed side having an input adapted for connection to a source of brine to fill the feed side with brine, the draw side having an input connected to the draw solution tank to fill the draw side with the draw solution, whereby water from the brine selectively passes through the semipermeable membrane by osmotic pressure and is mixed into the aqueous ethanol solution to form a dilute draw solution; and
an absorber column having a refrigerant inlet configured for receiving the refrigerant from the second heat exchanger and configured for receiving the dilute draw solution from the draw side of the forward osmosis filtration unit, the absorber column having a plurality of stages wherein the refrigerant directly contacts the dilute draw solution to separate desalinated, pure water from the dilute draw solution, the absorber column having a bottom water outlet for selectively releasing the pure, desalinated water and a top outlet for selectively releasing a mixture of the refrigerant and nonaqueous ethanol, the system being configured for returning the mixture of the refrigerant and nonaqueous ethanol to the refrigerant tank.
13. The combined acid gas removal and water filtration system as recited in claim 12 , wherein the first heat exchanger comprises a plate-plate heat exchanger.
14. The combined acid gas removal and water filtration system as recited in claim 13 , wherein the second heat exchanger comprises a plate-plate heat exchanger.
15. The combined acid gas removal and water filtration system as recited in claim 12 , further comprising a reboiler connected to the stripper and connected to an external source of saturated steam for mixing the heated solvent with the saturated steam and then stripping the acidic gases from the heated solvent in the stripper.
16. The combined acid gas removal and water filtration system as recited in claim 12 , further comprising a reflux drum in fluid communication with the first heat exchanger for receiving the acidic gas waste stream from the first heat exchanger for reflux thereof.
17. The combined acid gas removal and water filtration system as recited in claim 12 , further comprising a knock out drum connected to the gas inlet of the contactor for removing solid and liquid impurities from the stream of natural gas before feeding the natural gas into the contactor.
18. The combined acid gas removal and water filtration system as recited in claim 17 , further comprising a connection between the bottom water outlet of the absorber column and the draw solution tank, whereby a portion of the pure water released from the absorber column is recycled through the draw solution tank.