Systems and methods for removing multiple contaminants from a water stream

Abstract

A system for separating volatile hydrocarbons from a water stream includes a lead side mixer-injector device that receives an untreated water stream containing volatile hydrocarbons and injects compressed air into the untreated water stream to mix the injected air with the untreated water stream to form a first injected fluid stream. A shear mixing device receives the first injected fluid stream from the mixer-injector device and shears gas bubbles in the received first injected fluid stream to form a foamed stream. A lead side degasser separator receives the foamed stream from the shear mixing device and separates it based on density differences into a volatile hydrocarbon stream and a partially treated water stream. A compressor directs clean, oil-free compressed air to the lead side mixer-injector device.

Description

[Technical field]

[0001] Claiming priority

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 305,730, filed February 2, 2022, the contents of which are incorporated herein by reference.

[0002]

[0002] This disclosure relates generally to systems and methods for purifying water, and more particularly, to systems and methods for removing volatile hydrocarbons from water. [Background technology]

[0003]

[0003] Dissolved gases, including methane and other volatile hydrocarbons, can render groundwater recovered from wells unpotable due to appearance, bad taste, or health concerns. In addition, at high concentrations, methane and other dissolved volatile hydrocarbons can escape from the water quickly and pose an explosion hazard in poorly ventilated or enclosed areas. Systems and methods for removing methane and other volatile hydrocarbons from water are desired. Summary of the Invention [Means for solving the problem]

[0004]

[0004] There are multiple aspects of the subject matter of the present invention that may be embodied individually or together in the devices and systems described and claimed below. These aspects may be employed alone or in combination with other aspects of the subject matter described herein, and the description of these aspects, taken as a whole, is not intended to exclude the use of these aspects individually or to exclude the claiming of these aspects individually or in various combinations as set forth in the appended claims.

[0005] In one aspect, a system for separating volatile hydrocarbons from a water stream includes a lead side mixer-injector device that receives a raw water stream containing volatile hydrocarbons and injects compressed air into the pressurized raw water stream to mix the injected air with the raw water stream to form a first injected fluid stream. The air is injected using an air diffuser. A shear mixing device receives the first injected fluid stream from the mixer-injector device and shears gas bubbles in the received first injected fluid stream, resulting in the formation of a frothed stream. A lead side degasser separator receives the frothed stream from the shear mixing device and separates it based on density differences into a volatile hydrocarbon stream and a partially treated water stream. A compressor directs compressed air to the lead side mixer-injector device.

[0006]

[0006] In another aspect, a process for separating volatile hydrocarbons from a water stream includes injecting compressed air into a pressurized raw water stream; mixing the compressed air and the raw water stream to form a first injected fluid stream; shearing gas bubbles in the first injected fluid stream, thereby forming a foamed stream; and separating the foamed stream based on density differences into a volatile hydrocarbon stream and a partially treated water stream. [Brief description of the drawings]

[0007] [Figure 1] 1 is a piping and flow diagram illustrating an embodiment of the disclosed system and method. [Diagram 2]

[0008] FIG. 2 is a perspective view of an embodiment of the system of FIG. 1. [Diagram 3]

[0009] FIG. 3 is a plan view showing the system of FIG. 2. [Figure 4]

[0010] FIG. 4 is a side elevational view of an embodiment of an injector-mixer device of the system of FIGS. 1-3. [Diagram 5]

[0011] 5 is a side elevational view, partially cut away, showing an embodiment of an air diffuser of the system of FIGS. 1-3 installed within the injector-mixer of FIG. 4. FIG. [Figure 6]

[0012] FIG. 6 is an enlarged side elevational view of an embodiment of a solution tube of the aeration device of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008]

[0013] Although the following disclosure refers to treating water streams at the source and to systems that may be retrofitted to a prior source, the systems and methods of this disclosure may also be used further downstream or at other stages of water treatment.

[0009]

[0014] It should be noted that, herein, lines, pipes, conduits, passages, and similar structures, and corresponding streams, are all referred to by the same reference numerals, as may be the case, depicted in the figures.

[0010]

[0015] Reference numbers introduced herein in connection with a drawing figure may, if providing context for other features, be repeated in one or more subsequent figures for a common element or component without additional description herein.

[0011]

[0016] In the claims, letters are used to identify the claimed steps (e.g., a, b, and c). These letters are used to aid in referencing the method steps and are not intended to dictate the order in which the claimed steps are performed unless and only to the extent that an order is specifically recited in the claims.

[0012]

[0017] A first embodiment of the system of the present disclosure is shown generally at 10 in Figure 1. A pump 12 is disposed at the wellhead and provides a pressurized flow of untreated groundwater or well water to a junction forming lines 14 and 16. Line 16 is a system bypass line through which untreated groundwater or well water may be directed when a corresponding shutoff valve 18 is open and a shutoff valve 20 in line 14 is closed. In normal operation of the system of the present disclosure, valve 20 is open and valve 18 is closed.

[0013]

[0018] Groundwater or well water streams contain dissolved methane or dissolved natural gas, and potentially also contain entrained methane or entrained natural gas as well as other volatile hydrocarbons that may be dissolved or entrained, including but not limited to ethane and propane or other volatile hydrocarbons.

[0014]

[0019] After entering line 14, the water from pump 12 travels through a reducer 22 where the diameter of the conduit is reduced, resulting in an increase in water flow velocity to promote downstream mixing. By way of example only, reducer 22 may reduce the diameter of the line from 10 inches to 8 inches. The water flow then enters a lead side mixer-injector device 24, which may include a static mixer by way of example only and as will be described in more detail below.

[0015]

[0020] In the lead side mixer-injector device 24, the water stream passes into a static in-line mixer having blades or other mixing structures and an injector port where a stream of compressed air 26 is injected into the liquid water to cause mixing such that small air bubbles are formed in the liquid water. By way of example only, the mixer-injector can be the devices disclosed in U.S. Patent Nos. 4,123,800 and 5,863,128, both to Mazzei, the contents of both of which are incorporated herein by reference.

[0016]

[0021] The lead side mixer-injector device 24, which may be a static in-line mixer by way of example only, brings the water and air into intimate contact by introducing small bubbles of air into the water. The resulting turbulence creates an air scrubbing or air stripping process that physically removes dissolved gases from the solution, thereby forming bubbles of methane in the water.

[0017]

[0022] The efficiency of a scrubbing or stripping process depends, at least in part, on the magnitude of surface contact between the air and water, which is controlled primarily by the size of the air bubbles (smaller bubbles provide higher efficiency), the water velocity, and the mixing time in situ. Thus, the mixer-injector device 24 is equipped with an air diffuser, shown at 28 in FIG. 1, which covers the air flow path and may include a structure featuring a large number of small openings / holes or mesh. As a result, smaller air bubbles are allowed to form in the liquid water stream.

[0018]

[0023] An example of a suitable injector-mixer device is shown generally at 24 in Figure 4. The mixer-injector device 24 includes an injection port 25 that receives an air diffuser 28 as shown in Figure 5. With continued reference to Figure 5, the air diffuser 28 includes a valve body 29 secured to the mixer-injector device 24 and a solution tube 30 that extends into the mixer-injector fluid path 31. The valve body 29 and solution tube 30 receive the compressed air stream 26 shown in Figure 1. As shown in Figure 6, the solution tube includes a closed bottom 33 and a number of openings 35. The air stream 26 is injected through the openings 35 into the water stream flowing through the mixer-injector device. By way of example only, the mixer-injector device 24 may be an SMP series in-line static mixer available from Storm Mixer (www.stormmix.com), and the aeration device 28 may be a Model 5721 aeration device available from Inyo Process (www.inyoprocess.com).

[0019]

[0024] Injection fluid travels from the lead-side mixer-injector device 24 through a shear mixing device, such as flash reactors 34a-34c. Although three flash reactors are shown, the system may include one or another different number of flash reactors. Each flash reactor includes a mixing chamber having a structure that promotes turning and shearing the incoming gas and liquid water mixture. This creates a foam or froth, which in turn promotes mass transfer with the methane as it froths from the water for downstream separation. By way of example only, a suitable shear mixing device is the reactor disclosed in U.S. Patent No. 6,730,214 to Mazzei, the contents of which are incorporated herein by reference.

[0020]

[0025] The foamed stream exiting the flash reactors 34a-b then optionally travels through an expander 32 where the diameter of the conduit increases. By way of example only, the expander may expand the diameter of the conduit from 8 inches to 10 inches. The foamed stream then travels through line 36 to an optional reducer 38 where, by way of example only, the conduit diameter decreases from 10 inches to 8 inches. The foamed stream exiting the reducer 38 then enters a lead side degassing separator 42 equipped with a lead side degassing relief valve 43. Removed gas exits through the relief valve 43 to atmosphere 44.

[0021]

[0026] In the lead-side degasser separator 42, methane is separated from the incoming foam stream and exits the column as overhead stream 44 through lead-side degasser relief valve 43. The degasser relief valve allows air to escape while water is retained in separator 42. The lead-side degasser separates entrained and stripped methane (as well as other volatile hydrocarbons, if present) from the water based on the density difference between the gas and the liquid. The overhead stream 44 can be pure methane or can be a gas containing a high concentration of methane, which is transferred to the gas phase through the degasser relief valve. A liquid stream 46 of partially treated water exits the bottom of lead-side degasser separator 42.

[0022]

[0027] By way of example only, the lead-side degasser separator 42 may include technology disclosed in U.S. Patent No. 6,866,703 to Mazzei, U.S. Patent No. 5,622,545 to Mazzei et al., and / or U.S. Patent No. 5,338,341 to Mazzei et al., the contents of each of which are incorporated herein by reference. In such a degasser separator, the stream 37 exiting the reducer enters the top of the degasser separator 42 tangentially, causing the stream to rotate. The rotating water flows downward through the degasser separator 42 and exits at the bottom as liquid stream 46. Methane (and possibly other volatile hydrocarbons) gases collect in a vortex where they pass through a collector and flow out through the top of the degasser separator 42 via the degasser relief valve 43.

[0023]

[0028] A liquid stream 46 of the partially treated water, which may still contain some methane or other volatile hydrocarbons, flows into a lag-side mixer-injector device 50, which may be characterized in construction and operation similar to the lead-side mixer-injector device 24.

[0024]

[0029] As with the lead-side mixer-injector device 24, in the lug-side mixer-injector device 50, the water stream passes into a second in-line mixer and aeration combination having a mixer and an injector port where a stream of compressed air 52 is injected into the liquid water for mixing, resulting in the formation of small air bubbles in the liquid water. Given the tendency of methane and other VOC compounds to prefer the gas phase over the water phase, as explained above, the resulting turbulence causes methane bubbles to form in the water by air scrubbing. As with the lead-side mixer-injector device 24, the lug-side mixer-injector device 50 is equipped with an aeration diffuser 53, which includes a structure that covers the fluid flow path and features a number of small openings / holes or meshes.

[0025]

[0030] After leaving the lug mixer-injector device 50, the mixed phase fluid stream 54 enters a lead-side degassing separator 56 which is equipped with a lug-side degassing relief valve 58. Both the lug-side mixer-injector device 50 and the lug-side degassing relief valve 58 are characterized by construction and operation similar to that of the lead-side degassing separator 56 and the lead-side degassing relief valve 43.

[0026]

[0031] As in lead-side degasser separator 42, in rag-side degasser separator 56, methane is separated from stream 54 and exits the column as overhead stream 62 through rag-side degasser relief valve 58. A liquid stream 64 of treated water exits the bottom of rag-side degasser separator 56.

[0027]

[0032] A throttle valve may optionally be provided to reduce the pressure of stream 64 before the stream enters expander 68, thereby expanding the diameter of the conduit. By way of example only, the expander may expand the diameter of the conduit from 8 inches to 10 inches. Treated water stream 72 exits expander 68 and the system through valve 74.

[0028]

[0033] Although the embodiment of FIG. 1 shows a lead-side mixer-injector device and a lug-side mixer-injector device, as well as a lead-side degasser and a lug-side degasser, alternative embodiments of the system of the present disclosure may include one of each component or may include three or more of each component.

[0029]

[0034] Compressed air streams 26 and 52, which are clean, oil-free and filtered prior to use, are provided by a compressor 82 to the lead side mixer-injector device 24 and the lug side mixer-injector device 50. Compressed air from the compressor and air receiver tank combination and suitable oil coalescing filter 82 travels through an air line 84, through a throttle valve 86 and a rotameter 88 to form stream 26. Similarly, compressed air from the compressor 82 travels through an air line 94, a throttle valve 96, and a rotameter 98 to form stream 52.

[0030]

[0035] Compressor 82 is designed to operate in automatic mode and to supply air at the required pressure and flow rate on demand. Adjustable air rotameters 88 and 98 measure air flow in cubic feet per minute (CFM). By way of example only, the compressor may be capable of flow rates of 5.7 cubic meters per minute (200 CFM) to 8.5 cubic meters per minute (300 CFM) at 689 kPa (100 psi).

[0031]

[0036] Compressor 82 may optionally be equipped with a storage tank 83 (e.g., 240 gallons), a coalescing oil filter, or an oil / water separator (not shown) to manage drain line wastewater and / or to help minimize compressor cycles, as well as to conserve energy.

[0032]

[0037] Perspective and plan views of an example installation layout of the system of Figure 1 are presented in Figures 2 and 3, respectively, where common reference numerals are used. Figures 2 and 3 further show a wet well 102, to which water may be directed from pump 12 upon pump start-up.

[0033]

[0038] Test results of the systems of Figures 1-3 at water flow rates of 280 gallons per minute (gpm) to 300 gallons per minute (gpm) for degassing remediation at various ratios of air to water provided by each of the lead-side mixer-injector device 24 and the lug-side mixer-injector device 50 are presented below in Table 1. In Table 1, "raw methane" is the methane content of the raw untreated water in micrograms per liter (ug / L) versus "treated methane" is the methane content of the treated water in micrograms per liter (ug / L). In addition, the aeration devices of the lead-side mixer-injector device 24 and the lug-side mixer-injector device 50 each provide a back pressure of 10 psi.

[0034] [Table 1]

[0035]

[0039] Test results of the system of FIGS. 1-3 at water flow rates of 280 gpm to 300 gpm for degassing improvements at various ratios of air to water in each of the lead side mixer-injector device and the lug side mixer-injector device using air diffusers providing various back pressures in the lead side mixer-injector device 24 and the lug side mixer-injector device 50 are presented below in Table 2.

[0036] [Table 2]

[0037]

[0040] As shown in the table above, the preferred air to water ratio achieved by each of the lead side mixer-injector device 24 and the lug side mixer-injector device 50 is in the range of 0.80 to 1.50.

[0038]

[0041] Embodiments of the present disclosure remove both entrained and dissolved methane, as well as other volatile hydrocarbons, from water, where no significant changes in the quality parameters of the non-methane water of the treated water stream were observed.

[0039]

[0042] Additionally, embodiments of the present disclosure provide an in-line process that does not "lose" head pressure on the raw water stream. Embodiments of the present disclosure also do not feature an outlet that takes the treated water stream out at atmospheric pressure. These embodiments contrast with traditional air stripping systems and processes, and therefore may be used while maintaining pressure in a "closed" system, thereby reducing energy and capital costs.

[0040]

[0043] While preferred embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that changes and modifications can be made in the preferred embodiments of the invention without departing from the spirit of the invention.

Claims

1. 1. A system for separating volatile hydrocarbons from a water stream, comprising: a. a lead side mixer-injector device configured to receive an untreated water stream containing volatile hydrocarbons, inject compressed air into said untreated water stream, and mix said injected air with said untreated water stream to form a first injected fluid stream; b. a shear mixing device configured to receive the first infusion fluid stream from the mixer-injector device and shear gas bubbles in the received first infusion fluid stream, resulting in the formation of a foamed stream; c. a lead-side degasser separator configured to receive the foamed stream from the shear mixing device and separate the foamed stream based on density differences into a volatile hydrocarbon stream and a partially treated water stream; d. a compressor configured to direct clean, oil-free compressed air to the lead side mixer-injector device; A system comprising:

2. e. a lug-side mixer-injector device configured to receive compressed air and the partially treated water stream from the lead-side degasser separator containing residual volatile hydrocarbons, inject compressed air into the partially treated water stream, and mix the injected air with the partially treated water stream to form a second injected fluid stream; f. a lug-side degasser separator configured to receive the second injector stream from the lug-side mixer-injector and separate the second injector stream based on density difference into a second volatile hydrocarbon stream and a treated water stream; The system of claim 1 further comprising:

3. the lead side mixer-injector device and the lug side mixer-injector device each have an air diffuser including a plurality of openings or meshes; The system of claim 2.

4. a first line reducer disposed upstream of the lead side mixer-injector device; a first line expander disposed downstream of the lead side mixer-injector device; a second line reducer disposed upstream of the lead side degassing separator; and a second line expander disposed downstream of the lug side degassing separator. The system of claim 2 further comprising:

5. the lead-side degassing isolation device includes a lead-side degassing relief valve configured to open when pressure of volatile hydrocarbons in the lead-side degassing isolation device increases; the rag-side degassing separator including a rag-side degassing relief valve configured to open when the pressure of volatile hydrocarbons in the rag-side degassing separator increases above a predetermined level. The system of claim 2.

6. the lug side mixer-injector device receives compressed air from the compressor; The system of claim 2.

7. the shear mixing device comprises a plurality of flash reactors; The system of claim 1 .

8. a pump configured to direct a stream of untreated water to the lead side mixer-injector device. The system of claim 1 .

9. a line reducer disposed upstream of the lead side mixer-injector device; 10. The system of claim 1, further comprising: a line expander disposed downstream of the lead side mixer-injector device.

10. the lead-side degassing isolation device including a lead-side degassing relief valve configured to open when pressure of volatile hydrocarbons within the lead-side degassing isolation device increases; The system of claim 1 .

11. the lead side mixer-injector device includes an air diffuser having a plurality of openings or meshes; The system of claim 1 .

12. further comprising a throttling valve downstream from the lead side gas separation device. The system of claim 1 .

13. 1. A method for separating volatile hydrocarbons from a water stream, comprising the steps of: a. injecting compressed air into a stream of untreated water; b. mixing said compressed air and said raw water stream to form a first inlet fluid stream; c. shearing gas bubbles in the first injected fluid stream resulting in the formation of a foamed stream; d. separating said foam stream based on density differences into a volatile hydrocarbon stream and a partially treated water stream; A method comprising:

14. e. injecting compressed air into the partially treated water stream; f. mixing said compressed air and said partially treated water stream to form a second inlet fluid stream; g. separating said second input fluid stream into a volatile hydrocarbon stream and a treated water stream based on density differences; The method of claim 13 further comprising:

15. the air to water ratio in each of steps a and e is in the range of 0.80 to 1.50; The method of claim 14.

16. The volatile hydrocarbons include methane. The method of claim 13.

17. further comprising throttling and regulating the treated water flow. The method of claim 13.

18. Further comprising pumping the untreated water prior to step a. The method of claim 13.

19. The untreated water is well water or groundwater; 20. The method of claim 18.

20. the air to water ratio in step a is in the range of 0.80 to 1.50; The method of claim 13.

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