CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
BACKGROUND
This disclosure is related to the field of gas compression and separation, primarily used in crude oil refining, petrochemicals and other industrial applications.
A process known in the art for recovering hydrogen-rich gasses and increasing the recovery of liquid hydrocarbon products comprises a separator, a compressor, a cooler, a final separator, a molecular sieve-type separation system, wherein a separator is connected by liquid product with a cooler, and by gaseous product with a compressor. The compressor discharge is connected with a cooler, and the cooler is connected with a final separator, wherein the final separator is connected by a gaseous product with a molecular sieve-type separator system. In the molecular sieve-type separator, raw vapor-liquid mixture is fed to a separator and separated into liquid and gaseous phases. The gaseous phase is fed to a compressor for compression, and the liquid phase is moved to a cooler mixing with a compressed gas coming from the discharge of a compressor, wherein a liquid-gas mixture heat is absorbed in a cooler. The cooled liquid-gas mixture is separated into liquid and gaseous products in a final separator, wherein a gaseous product from a final separator is fed to a molecular sieve-type separator system wherein heavy hydrocarbons are separated from a final gaseous product, and partially recycled to the suction of a compressor and partially are sent to consumers (see U.S. Pat. No. 5,332,492 issued Jul. 26, 1994).
SUMMARY
A condensing and absorbing gas compression unit according to one aspect includes a cooler. A product outlet of the cooler is coupled to an inlet of a separator. A liquid outlet of the separator is coupled to an inlet of a pump. The pump outlet is coupled to a condensing unit, wherein the condensing unit comprises a condensing liquid-driven gas ejector A liquid-driven ejector product outlet is connected to an inlet of the cooler.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 represents a schematic diagram of an example condensing and absorbing gas compression unit.
FIG. 2 represents a schematic diagram of the described condensing and absorbing gas compression unit, which includes a partial gas recycle.
FIG. 3 represents a schematic diagram of the described condensing and absorbing gas compression unit, which includes a liquid makeup from an outside source.
FIG. 4 represents a schematic diagram of the described condensing and absorbing gas compression unit, which includes the additional cooler.
FIG. 5 represents a schematic diagram of the described condensing and absorbing gas compression unit, wherein the separator is a three-phase separation vessel.
FIG. 6 shows a detailed view of a liquid driven gas ejector.
FIG. 7 shows another view of the gas ejector of FIG. 6.
DETAILED DESCRIPTION
FIG. 1 represents a schematic diagram of the described condensing and absorbing gas compression unit. Raw feed gas (2) from an outside source (1) is fed to the gas inlet port (3A) of a liquid-driven gas ejector (3), wherein the ejector liquid inlet port (3B) is connected with a recirculating pump (13) liquid outlet port (13B) to supply a motive liquid (14) to the ejector (3), wherein the ejector discharge port (3C) is connected through a cooler (5) with the inlet port (7A) of a separator (7). Gaseous product (8) from the separator (7) is directed to the outside consumers and liquid product is sent to a first tee (10). In the first tee (10) a part (12) of the separator liquid product (9) is withdrawn from the system and sent to consumers, and another part (11) is directed to the pump (13) inlet port (13A).
The ejector (3) operates at full condensation with liquid discharge at its outlet (3C). To obtain full condensation, the ejector motive fluid weight flow rate may be in a range of from 3.3 to 500 times the weight flow rate of the compressed gas entering the ejector (3) gas inlet port (3A).
As shown in FIG. 1, the motive liquid (14) is pumped by the recirculating pump (13) in the closed loop through the liquid-driven condensing gas ejector (3), cooler (5) and separator (7). The raw feed gas (2), which may have a multi-component composition is conducted to the ejector (3) gas inlet port (3A) from the source (1). The motive liquid (14) enters the ejector (3) through the liquid inlet port (3B) at a high static pressure. By passing through the ejector motive fluid nozzle tip as shown in FIG. 6 and FIG. 7, the motive liquid accelerates to high velocity, converting high static pressure to high kinetic energy, and enters the ejector throat entrance (see FIG. 6 and FIG. 7). In the ejector throat entrance, the motive liquid at high velocity entrains the gas entering the ejector feed zone, wherein the resulting gas-liquid mixture equalizes in linear velocity reaching sonic flow conditions and moves through the shock wave established by the sonic flow regime within the ejector throat (shown at 3E in FIG. 6 and FIG. 7). In the ejector throat, the static pressure of the two-phase flow increases resulting in condensation of condensable components of the raw feed gas, which causes instantaneous collapse of the fluid volume and deceleration of the flow followed by a secondary shock wave and consequent second static pressure increase. Simultaneously, with such increase of the static pressure in the ejector throat (3E in FIG. 6 and FIG. 7), due to highly atomized liquid phase blended with the raw feed gas to near homogeneous conditions, the resulting liquid, which is rich with heavy components, absorbs high molecular weight content from the gas. To reduce the temperature rise of the compressed gas in the ejector throat and to maintain near isothermal compression conditions, and to increase extraction of heavy components from the gas by shifting phase equilibrium to heavy molecular weight side, the motive liquid to gas weight flow rates ratio may be set within the range from 3.3 to 500 depending upon gas and liquid properties and motive liquid pressure available, which is provided by the circulating pump (13). Upon exiting the ejector through the ejector discharge port, the fluid is directed to the cooler (5) to remove the heat of condensation and absorption prior separation in the separator (7) to preserve heavy components absorbed in the liquid from being flashed and lost with separator gaseous product. After cooling in the cooler (5) the mixture (6) is separated in the separator (7) into gaseous and liquid products, wherein the liquid product includes heavy components condensed and absorbed from the raw feed gas, and it is sent to the tee (10), where part of the liquid product is drawn from the system, and part is directed to the recirculating pump (13) to recycle and to be used as a motive fluid to operate the ejector. Since the motive liquid is separated from the gaseous product in the separator (7) at a higher pressure than it is in the ejector feed zone (FIG. 6 and FIG. 7), and light components tend to flash when entering the ejector feed zone and moving through the ejector throat and to increase gas flowrates simultaneously reducing the ejector capacity, the distance between the end of the ejector motive fluid nozzle tip and the ejector throat entrance (parameter Lh in FIG. 6 and FIG. 7) may be set from 0.12 to 5.0 inches, and a pressure at the ejector liquid nozzle (3B) may be not less than 350 psig (pounds per square inch gauge) to ensure high enough velocity of the motive fluid passing through the ejector feed zone and the ejector throat entrance, and not more than 5600 psig to prevent unsteady liquid flow conditions.
FIG. 2 represents a schematic diagram of the above described condensing and absorbing gas compression unit, which includes a partial gas recycle. Raw feed gas (2) from the outside source (1) is mixed with recycle gas (23) from a second tee (21), and the mixture (24) is fed to the gas inlet port (3A) of the liquid-driven gas ejector (3), wherein the ejector liquid inlet port (3B) is connected with the pump (13) liquid outlet port (13B) to supply a motive fluid (14) to the gas ejector (3), wherein the ejector discharge port (3C) is connected through the cooler (5) with the inlet port (7A) of the separator (7). From the separator (7), gaseous product (8) is directed to the second tee (21) where it is divided into a recycle gas stream (23) and gaseous product (22) that is directed to outside consumers. Liquid product (9) from the separator (7) is sent to the first tee (10), wherein a part (12) of the separator liquid product (9) is withdrawn from the system and sent to consumers, and another part (11) is directed to the pump (13) inlet port (13A). FIG. 2 shows substantially the process as explained with reference to FIG. 1, where to increase heavy component recovery from the gaseous product, the gaseous product (8) from the separator (7) is split into a part (17) that is recycled back to the ejector (3) and another part (16) that is sent to outside consumers.
FIG. 3 represents a schematic diagram of the described condensing and absorbing gas compression unit, which includes a liquid makeup from outside source. Raw feed gas (2) from the outside source (1) is fed to the gas inlet port (3A) of the liquid-driven gas ejector (3), wherein the ejector liquid inlet port (3B) is connected with a mixer (36) fed by a motive fluid (14) recycled from the pump (13) liquid outlet port (13B) and by an additional liquid stream (35) from an outside source (34) to supply a motive fluid (37) to the ejector (3). The ejector discharge port (3C) is connected through the cooler (5) with the inlet port (7A) of the separator (7), wherein gaseous product (8) is directed to the outside consumers and liquid product is sent to the first tee (10), wherein a part (12) of the separator liquid product (9) is withdrawn from the system and sent to consumers, and another part (11) is directed to the mixer (32). The part (11) directed to the mixer (32) is mixed with the makeup product (31) from outside source (30), wherein the liquid mixture directed to the pump inlet port (13A). The liquid makeup could be any property media being in liquid phase under the same temperature andpressure as in separator (7). FIG. 3 demonstrates the same process as explained with reference to FIG. 1, with the increase of heavy components recovered from the gaseous product being achieved by making up the motive liquid (14) with a lean absorbent (16) from an outside source (15), wherein in specific cases when the raw feed gas (2) composition includes components that have to be removed or washed out to prevent corrosion or solid salt formation. To do this, the inhibitor (20) from the outside source (19) is injected into the motive liquid (14), and the resulting liquid mixture (22) is used as a motive fluid for ejector (3).
FIG. 4 represents a schematic diagram of the described condensing and absorbing gas compression unit, which includes an additional cooler. Raw feed gas (2) from the outside source (1) is fed to the gas inlet port (3A) of the liquid-driven gas ejector (3), wherein the ejector liquid inlet port (3B) is connected with the pump (13) liquid outlet port (13B) to supply a motive fluid (14) to the ejector (3). The ejector discharge port (3C) is connected through the cooler (5) to the inlet port (7A) of the separator (7), wherein gaseous product (8) is directed to the outside consumers and liquid product is sent to the first tee (10). From the first tee (10) a part (12) of the separator liquid product (9) is withdrawn from the system and sent to consumers, and another part (11) is directed to the inlet port (41A) of additional cooler (41) wherein the outlet port (41B) is connected with the inlet port (13A) of circulating pump (13). FIG. 4 illustrates the same process as explained with reference to FIG. 1, but wherein to improve heavy component recovery from the gaseous product (8) an additional cooler (15) is installed between the separator (7) and the recirculating pump (13). The additional cooler (15) could be a reversed cooler, or a heater. The additional cooler or heater (15) may be used when a different separator (7) outlet temperature is required during the compression. Such could be due to a variety of reasons including chemical reactions or a preferred shift in the liquid-vapor phase equilibrium in the ejector (3) and at the cooler (5).
FIG. 5 represents a schematic diagram of the described condensing and absorbing gas compression unit, wherein the separator is a three-phase separation vessel. Raw feed gas (2) from the outside source (1) is fed to the gas inlet port (3A) of the liquid-driven gas ejector (3), wherein the ejector liquid inlet port (3B) is connected with the pump (13) liquid outlet port (13B) to supply a motive fluid (14) to the ejector (3). The ejector discharge port (3C) is connected through the cooler (5) with the inlet port (7A) of the separator (7), which in the present example may be a three phase separation vessel, wherein gaseous product (8) is directed to the outside consumers. Heavy liquid product (51) is drawn from a heavy liquid separator port (7D), and the light liquid product (9) is sent to the first tee (10), wherein a part (12) of the separator liquid product (9) is withdrawn from the system and sent to consumers, and another part (11) is directed to the pump (13) inlet port (13A). FIG. 5 shows substantially the same process ex explained with reference to FIG. 1 but wherein the separator (7) may be a three-phase separation vessel, with heavy liquid drawn from the heavy liquid product port (7D), light liquid product drawn from the light liquid port port (7C), and gaseous product leaving the separator from the gas product port (7B). The example of FIG. 5 may be used when separation of light and heavy liquids is required.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
Patent Application
20150184907
