Gas field water resource recovery method and system

Abstract

This invention provides a method and system for recovering water resources from gas fields. The method includes: subjecting gas field water to media filtration and / or ultrafiltration membrane filtration to obtain pretreated gas field water; adsorbing lithium from the pretreated gas field water using a lithium adsorbent to obtain adsorbed tailings water; desorbing lithium from the lithium adsorbent after adsorption to obtain a lithium-containing solution; subjecting the adsorbed tailings water to acidification and oxidation treatments sequentially to obtain an oxidized liquid; and subjecting the oxidized liquid to air stripping to obtain gaseous bromine. This method for recovering water resources from gas fields can efficiently recover lithium, bromine, and other resources from gas field water, achieving full utilization of gas field water resources.

Description

Technical Field

[0001] This invention relates to a method and system for recovering water resources in gas fields, belonging to the field of gas field water treatment. Background Technology

[0002] Reinjecting treated gas field water can reduce pollution to the ecological environment and avoid wasting water resources. Therefore, injecting treated gas field water back into the underground oil layer is the most common treatment method in oil fields today.

[0003] The lithium and bromine content in gas field water is higher than the minimum industrial grade, indicating potential resource utilization value. With the booming development of new energy vehicles, lithium consumption is increasing dramatically, making the extraction and recovery of lithium and bromine resources from gas field water economically valuable. Currently, gas field water treatment mainly involves water reuse and reinjection into underground oil reservoirs, without effectively recovering lithium and bromine resources. Therefore, it is necessary to provide a new method for recovering gas field water resources to address these issues. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a method and system for recovering water resources in gas fields. This method can efficiently recover resources such as lithium and bromine from gas field water, thereby achieving full utilization of gas field water resources.

[0005] To achieve the above objectives, the present invention provides a method for recovering water resources in a gas field, comprising the following steps:

[0006] Pretreatment steps: The gas field water is subjected to media filtration and / or ultrafiltration membrane filtration to obtain pretreated gas field water;

[0007] Lithium extraction steps: lithium adsorption is performed on pretreated gas field water using a lithium adsorbent to obtain adsorbed tail water; and after lithium adsorption, lithium desorption is performed on the lithium adsorbent to obtain a lithium-containing solution.

[0008] Bromine extraction steps: The adsorption tail water is subjected to acidification and oxidation treatment in sequence to obtain an oxidized liquid; the oxidized liquid is then subjected to air stripping to obtain gaseous bromine.

[0009] First, compared to typical salt lake brine, gas field water has a more complex composition of impurities and coexisting ions, containing a higher amount of suspended solids (SS), oily substances, and small-molecule organic matter. These impurities can adversely affect the efficiency of subsequent adsorption and membrane separation processes, as well as product purity. For example, oily substances and suspended solids can physically clog the pores of adsorbents and membrane materials, reducing their adsorption and separation performance. This invention pre-treats the gas field water, removing suspended solids (SS), oily substances, and small-molecule organic matter, thereby avoiding the adverse effects of these impurities on the efficiency of subsequent adsorption and membrane separation processes and product purity.

[0010] Secondly, the lithium and bromine resources in gas field water are low in content and difficult to extract, making it challenging to extract these resources using conventional lithium and bromine extraction processes. This invention utilizes a lithium adsorbent to effectively recover lithium from the gas field water. After lithium extraction, the aforementioned bromine extraction process is performed, effectively recovering bromine from the gas field water. Furthermore, this invention, while effectively recovering bromine from the gas field water, avoids the problem of repeated pH adjustments, reducing the amount of acid and alkali used (lithium adsorbents are generally suitable for neutral pH conditions; while bromine extraction requires acidification and is suitable for acidic pH conditions).

[0011] Furthermore, the average pore size of the ultrafiltration membrane is 0.002–0.5 μm; the molecular weight cutoff of the ultrafiltration membrane is 10,000–5,000,000 Da; and the media includes quartz sand filter media and / or activated carbon.

[0012] Furthermore, the average pore size of the filter membrane is 0.05–0.1 μm, for example, 0.05 μm, 0.75 μm, or 0.1 μm; the molecular weight cutoff of the ultrafiltration membrane is 20,000–5,000,000 Da, for example, 20,000 Da, 100,000 Da, 500,000 Da, 1,000,000 Da, or 5,000,000 Da.

[0013] Furthermore, the adsorption flow rate during the lithium adsorption process is 1–20 BV / h; the desorption flow rate during the lithium desorption process is 1–30 BV / h.

[0014] Furthermore, the adsorption flow rate during the lithium adsorption process is 5–15 BV / h; the desorption flow rate during the lithium desorption process is 4–12 BV / h.

[0015] Further, the lithium adsorbent is selected from one or more combinations of aluminum-based adsorbents, manganese-based adsorbents, and titanium-based adsorbents. In some optional embodiments, the lithium adsorbent can be selected from aluminum-based adsorbents, wherein the adsorption component of the aluminum-based adsorbent is lithium aluminum layered double hydroxide, and the aluminum layered double hydroxide is granulated by a binder to obtain the aluminum-based lithium adsorbent. In some optional embodiments, the lithium adsorbent can be selected from titanium-based adsorbents, wherein the adsorption component of the titanium-based adsorbent is a spinel-type titanium oxide ion sieve. For example, the aluminum adsorbent is JW-LAHS-03 from Jiuwu High-Tech, and the titanium adsorbent is JW-LTOS-03 from Jiuwu High-Tech.

[0016] Furthermore, after lithium extraction, the gas field water resource recovery method also includes the following steps:

[0017] Concentration step: The lithium-containing solution is concentrated to obtain a lithium-rich solution;

[0018] Precipitation step: Carbonate is added to the lithium-rich solution to carry out a precipitation reaction, yielding lithium carbonate. In some alternative embodiments, the lithium-rich solution can also be treated by electrodialysis to obtain lithium hydroxide, which is well known to those skilled in the art and will not be described in detail here.

[0019] Absorption step: Gaseous bromine is absorbed by an aqueous solution of sulfur dioxide to obtain hydrobromic acid. The reaction involved is: Br2 + SO2 + 2H2O → H2SO4 + 2HBr.

[0020] Furthermore, the concentration method is reverse osmosis membrane concentration and / or electrodialysis membrane concentration. In some optional embodiments, the organic membrane used in the concentration is a spiral wound membrane module, and the membrane material can be selected from one or more combinations of PVC, PEEK, PES, PS, PP, PET and PVDF.

[0021] In one preferred embodiment, the concentration includes sequentially performing a first-stage reverse osmosis membrane concentration, a second-stage reverse osmosis membrane concentration, and an evaporative concentration; the operating pressure of the first-stage reverse osmosis membrane concentration is 3.0–3.5 MPa, and the operating pressure of the second-stage reverse osmosis membrane concentration is 7.5–8.0 MPa. In another preferred embodiment, the concentration includes sequentially performing a first-stage reverse osmosis membrane concentration, a second-stage electrodialysis membrane concentration, and an evaporative concentration; the operating pressure of the first-stage reverse osmosis membrane concentration is 3.0–3.5 MPa, and the current efficiency of the second-stage electrodialysis membrane concentration is 64–71%.

[0022] In some alternative embodiments, the lithium-containing solution is concentrated to a lithium ion concentration of 15–25 g / L.

[0023] Furthermore, an acid is added to the system to control the pH value to 2–4. The acid can be hydrochloric acid or nitric acid.

[0024] Furthermore, the oxidant used in the oxidation process is chlorine gas, and the amount of chlorine gas introduced is 110-140% of the chlorine ratio in the bromine-chlorine reaction.

[0025] In some optional implementations, gas field water refers to the desulfurized (desulfurization method is conventional methods such as gas stripping desulfurization or oxidative desulfurization) produced water during the gas field extraction process, wherein the COD is 1-300 ppm; TOC is 1-100 ppm; oily substances content is 1-100 ppm; lithium ion content is 10-300 ppm; magnesium ion content is 0.1-1.0 g / L; sulfate content is 1-300 ppm; and pH value is 5-9. COD and TOC are commonly used indicators of organic matter content in reaction water in the water treatment industry.

[0026] This invention also provides a gas field water resource recovery system, which includes a pretreatment unit, a lithium extraction unit, and a bromine extraction unit; the pretreatment unit includes a media filtration device and / or an ultrafiltration membrane filtration device; the lithium extraction unit includes a lithium adsorption tower; the bromine extraction unit includes a reaction tank, a stripping tower, and an absorption tower; the lithium adsorption tower has a pretreated gas field water inlet, a desorption solvent inlet, a lithium-containing solution outlet, and an adsorption tailwater outlet; the pretreated gas field water inlet of the lithium adsorption tower is connected to the outlet of the pretreatment unit; the inlet of the reaction tank is connected to the adsorption tailwater outlet; and the reaction tank also has an acid feed inlet and an oxidant feed inlet; the inlet at the top of the stripping tower is connected to the outlet of the reaction tank; and the bottom of the stripping tower has an air inlet; the inlet of the absorption tower is connected to the outlet at the top of the stripping tower; and sulfur dioxide is provided inside the absorption tower.

[0027] After being filtered by a media filtration device and / or an ultrafiltration membrane filtration device, the gas field water continues to enter the lithium adsorption tower through the pretreated gas field water inlet for lithium adsorption, resulting in adsorption tail water. After lithium adsorption, the lithium adsorbent is desorbed to obtain a lithium-containing solution. The lithium-containing solution is discharged from the lithium-containing solution outlet, and the adsorption tail water is discharged from the adsorption tail water outlet and enters the reaction tank. In the reaction tank, acidification and oxidation treatments are carried out in sequence to obtain an oxidizing liquid. The oxidizing liquid enters from the top of the stripping tower and is sprayed down. The bromine molecules in the oxidizing liquid are stripped by the air flowing from bottom to top in the stripping tower, forming air containing bromine molecules, which is blown out from the top of the stripping tower to obtain gaseous bromine.

[0028] Furthermore, the lithium extraction unit also includes a concentration device and a precipitation reaction device; the inlet of the concentration device is connected to the lithium-containing solution outlet of the lithium adsorption tower; the inlet of the precipitation reaction device is connected to the outlet of the concentration device, and the precipitation reaction device has a carbonate feed port.

[0029] Furthermore, the concentration unit includes a first-stage membrane concentration unit, a second-stage membrane concentration unit, and an evaporation concentration unit connected in sequence; the membrane in the first-stage membrane concentration unit is a reverse osmosis membrane; the membrane in the second-stage membrane concentration unit is a reverse osmosis membrane or an electrodialysis membrane.

[0030] Furthermore, the bromine extraction unit also includes an absorption tower; the inlet of the absorption tower is connected to the gaseous bromine outlet at the top of the stripping tower; and sulfur dioxide is installed inside the absorption tower. The sulfur dioxide absorbs the gaseous bromine to produce hydrogen bromide.

[0031] Based on the reasons stated above, this invention can effectively extract resources such as lithium and bromine from gas field water, obtain industrial-grade lithium products and industrial-grade bromine products, and realize the full utilization of gas field water resources. Attached Figure Description

[0032] Figure 1 A schematic diagram of a gas field water resource recovery system according to one embodiment of the present invention is shown.

[0033] Figure 2 A flowchart of a gas field water resource recovery method according to one embodiment of the present invention is shown;

[0034] The components include: 1. filtration device; 2. lithium adsorption tower; 3. reaction vessel; 4. stripping tower; 5. absorption tower; 6. concentration device; and 7. precipitation reaction device. Detailed Implementation

[0035] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0036] Example 1

[0037] (I) This embodiment provides a gas field water resource recovery system, such as Figure 1 As shown, it includes a pretreatment unit, a lithium extraction unit, and a bromine extraction unit connected in sequence; wherein,

[0038] (1) The pretreatment unit includes a filtration device 1, which is an activated carbon filter;

[0039] (2) The lithium extraction unit includes a lithium adsorption tower 2, a concentration device 6, and a precipitation reaction device 7.

[0040] Lithium adsorption tower 2 has a pretreatment gas field water inlet, a desorption solvent inlet (for introducing the desorption solvent), a lithium-containing solution outlet, and an adsorption tailwater outlet;

[0041] The pretreatment gas field water inlet of lithium adsorption tower 2 is connected to the discharge port of filter device 1;

[0042] The lithium-containing solution outlet of lithium adsorption tower 2 is connected to the feed inlet of concentration device 6;

[0043] The inlet of the precipitation reaction device 7 is connected to the outlet of the concentration device 6, and the precipitation reaction device 7 has a carbonate inlet.

[0044] The concentration unit 6 includes a first-stage reverse osmosis membrane concentration system, a second-stage reverse osmosis membrane concentration system, and an evaporation concentration system connected in sequence.

[0045] (3) The bromine extraction unit includes a reaction tank 3, a stripping tower 4, and an absorption tower 5; among which...

[0046] The feed inlet of reaction vessel 3 is connected to the adsorption tailwater outlet of lithium adsorption tower 2;

[0047] Reaction vessel 3 has an acid inlet and a chlorine inlet;

[0048] The discharge port of reaction vessel 3 is connected to the feed port at the top of stripping tower 4, and an air inlet is provided at the bottom of stripping tower 4;

[0049] The feed inlet of the absorption tower 5 is connected to the discharge outlet at the top of the stripping tower 4; sulfur dioxide is installed inside the absorption tower 5.

[0050] (II) This embodiment provides a method for recovering water resources in a gas field, such as... Figure 2 As shown, it includes the following steps:

[0051] Gas field water with a lithium ion content of 70 mg / L, a bromide ion content of 500 ppm, an oily substance content of 3 mg / L, a TOC content of 15 mg / L, a sulfate content of 28 mg / L, a magnesium ion content of 0.32 g / L, and a chloride ion content of 10 g / L was pumped into filtration device 1 (activated carbon filter) to remove suspended solids and oily substances. At a flow rate of 10 m / h and a pressure of 0.2 MPa, the turbidity of the effluent was <3 NTU.

[0052] The effluent from filter device 1 (activated carbon filter) is pumped into lithium adsorption tower 2 (filled with JW-LAHS-03 aluminum adsorbent) for lithium adsorption. The influent flow rate is 12 BV / h. After adsorption, desorption is performed (soft water with a TDS value of 110 mg / L is used as the desorption solvent in lithium adsorption tower 2). The desorption influent flow rate is 10 BV / h, and the desorption water temperature is 40℃. The lithium content in the desorbed lithium-containing solution is 160 mg / L, and the lithium concentration in the adsorption tail water is 14.38 mg / L.

[0053] The lithium-containing solution undergoes preliminary lithium concentration in the first-stage reverse osmosis membrane concentration system of concentration unit 6 (operating pressure 3.0–3.5 MPa), yielding a first-stage reverse osmosis membrane concentrate (with a lithium recovery rate of 95%, i.e., the weight content of lithium in the first-stage reverse osmosis membrane concentrate / the weight content of lithium in the lithium-containing solution × 100%) and a first-stage reverse osmosis membrane permeate. The first-stage reverse osmosis membrane concentrate further enters the second-stage reverse osmosis membrane concentration system for deep concentration (operating pressure 7.5–8.0 MPa), yielding a second-stage reverse osmosis membrane concentrate (with a lithium recovery rate of 70%, i.e., the weight content of lithium in the second-stage reverse osmosis membrane concentrate / the weight content of lithium in the first-stage reverse osmosis membrane concentrate × 100%) and a second-stage reverse osmosis membrane permeate. The second-stage reverse osmosis membrane concentrate enters the evaporation concentration system for further concentration, yielding a lithium-rich solution with a lithium content of 22 g / L. The first-stage and second-stage membrane permeates are refluxed as desorption solvents in lithium adsorption tower 2.

[0054] The lithium-rich solution enters the precipitation reaction device 7, and a sodium carbonate aqueous solution with a sodium carbonate mass concentration of 20% is added to precipitate lithium carbonate. The product is washed and centrifuged to obtain lithium carbonate product. The purity of the lithium carbonate product is 99.1%, and the final lithium yield is 71% (i.e., the weight of lithium carbonate product / the weight content of lithium in the raw gas field water × 100%).

[0055] The adsorption tailwater enters reaction tank 3 for acidification treatment (pH value 2-4) to obtain acidified gas field water. Chlorine gas is then introduced into reaction tank 3 for oxidation reaction to obtain oxidized liquid. The amount of chlorine gas introduced is 120% of the chlorine ratio of the bromine-chlorine reaction.

[0056] The oxidizing liquid enters from the top of the stripping tower 4 and is sprayed downwards. Bromine molecules in the oxidizing liquid are stripped by air flowing upwards inside the stripping tower, forming gaseous bromine, which is then blown out from the top of the stripping tower 4 and enters the absorption tower 5. The purity of the gaseous bromine is 99.8%, and the bromine recovery rate is 86% (i.e., (bromine ion content in the raw gas field water - bromine ion content in the oxidizing liquid after oxidative stripping) / bromine ion content in the raw gas field water × 100%).

[0057] Example 2

[0058] (I) This embodiment provides a gas field water resource recovery system, such as Figure 1 As shown, it includes a pretreatment unit, a lithium extraction unit, and a bromine extraction unit connected in sequence; wherein,

[0059] (1) The pretreatment unit includes a filtration device 1, which is an activated carbon filter;

[0060] (2) The lithium extraction unit includes a lithium adsorption tower 2, a concentration device 6, and a precipitation reaction device 7.

[0061] The concentration unit 6 includes a first-stage reverse osmosis membrane concentration system, a second-stage reverse osmosis membrane concentration system, and an evaporation concentration system connected in sequence.

[0062] Lithium adsorption tower 2 has a pretreatment gas field water inlet, a desorption solvent inlet (for introducing the desorption solvent), a lithium-containing solution outlet, and an adsorption tailwater outlet;

[0063] The pretreatment gas field water inlet of lithium adsorption tower 2 is connected to the discharge port of filter device 1;

[0064] The lithium-containing solution outlet of lithium adsorption tower 2 is connected to the feed inlet of concentration device 6;

[0065] The inlet of the precipitation reaction device 7 is connected to the outlet of the concentration device 6, and the precipitation reaction device 7 has a carbonate inlet.

[0066] (3) The bromine extraction unit includes a reaction tank 3, a stripping tower 4, and an absorption tower 5; among which...

[0067] The feed inlet of reaction vessel 3 is connected to the adsorption tailwater outlet of lithium adsorption tower 2;

[0068] Reaction vessel 3 has an acid inlet and a chlorine inlet;

[0069] The discharge port of reaction vessel 3 is connected to the feed port at the top of stripping tower 4, and an air inlet is provided at the bottom of stripping tower 4;

[0070] The feed inlet of the absorption tower 5 is connected to the discharge outlet at the top of the stripping tower 4; sulfur dioxide is installed inside the absorption tower 5.

[0071] (II) This embodiment provides a method for recovering water resources in a gas field, such as... Figure 2 As shown, it includes the following steps:

[0072] Gas field water with a lithium ion content of 110 mg / L, a bromide ion content of 700 ppm, an oil content of 5 mg / L, a TOC content of 50 mg / L, a sulfate content of 35 mg / L, a magnesium ion content of 0.38 g / L, and a chloride ion content of 11 g / L was pumped into filtration device 1 (activated carbon filter) to remove suspended solids and oily substances. At a flow rate of 8 m / h and a pressure of 0.2 MPa, the turbidity of the effluent was <3 NTU.

[0073] The effluent from filter device 1 (activated carbon filter) is pumped into lithium adsorption tower 2 (filled with JW-LAHS-03 aluminum adsorbent) for lithium adsorption. The influent flow rate is 15 BV / h. After adsorption, desorption is performed (soft water with a TDS value of 100 mg / L is used as the desorption solvent). The influent flow rate for desorption is 12 BV / h, and the desorption water temperature is 40℃. The lithium content in the desorbed lithium-containing solution is 180 mg / L, and the lithium concentration in the adsorption tail water is 20.38 mg / L.

[0074] The lithium-containing solution undergoes preliminary lithium concentration in the first-stage reverse osmosis membrane concentration system of concentration unit 6 (operating pressure 3.0–3.5 MPa), yielding a first-stage reverse osmosis membrane concentrate (with a lithium recovery rate of 95%, i.e., the weight content of lithium in the first-stage reverse osmosis membrane concentrate / the weight content of lithium in the lithium-containing solution × 100%) and a first-stage reverse osmosis membrane permeate. The first-stage reverse osmosis membrane concentrate further enters the second-stage reverse osmosis membrane concentration system for deep concentration (operating pressure 7.5–8.0 MPa), yielding a second-stage reverse osmosis membrane concentrate (with a lithium recovery rate of 70%, i.e., the weight content of lithium in the second-stage reverse osmosis membrane concentrate / the weight content of lithium in the first-stage reverse osmosis membrane concentrate × 100%) and a second-stage reverse osmosis membrane permeate. The second-stage reverse osmosis membrane concentrate enters the evaporation concentration system for further concentration, yielding a lithium-rich solution with a lithium content of 21.8 g / L. The first-stage and second-stage membrane permeates are refluxed as desorption solvents.

[0075] The lithium-rich solution enters the precipitation reaction device 7, and a sodium carbonate aqueous solution with a sodium carbonate mass concentration of 20% is added to precipitate lithium carbonate. The product is washed and centrifuged to obtain lithium carbonate with a purity of 98.8% and a lithium yield of 75% (i.e., the weight of lithium carbonate product / the weight content of lithium in the raw gas field water × 100%).

[0076] The adsorption tailwater enters reaction tank 3 for acidification treatment (pH value 2-4) to obtain acidified gas field water. Chlorine gas is then introduced into reaction tank 3 for oxidation reaction to obtain oxidized liquid. The amount of chlorine gas introduced is 120% of the chlorine ratio of the bromine-chlorine reaction.

[0077] The oxidizing liquid enters from the top of the stripping tower 4 and is sprayed downwards. Bromine molecules in the oxidizing liquid are stripped by air flowing upwards inside the stripping tower, forming gaseous bromine, which is then blown out from the top of the stripping tower 4 and enters the absorption tower 5. The purity of the gaseous bromine is 99.8%, and the bromine recovery rate is 88% (i.e., (bromine ion content in the raw gas field water - bromine ion content in the oxidizing liquid after oxidizing and stripping) / bromine ion content in the raw gas field water × 100%).

[0078] Example 3

[0079] (I) This embodiment provides a gas field water resource recovery system, such as Figure 1 As shown, it includes a pretreatment unit, a lithium extraction unit, and a bromine extraction unit connected in sequence; wherein,

[0080] (1) The pretreatment unit includes a filtration device 1, which is an ultrafiltration membrane system;

[0081] (2) The lithium extraction unit includes a lithium adsorption tower 2, a concentration device 6, and a precipitation reaction device 7.

[0082] The concentration unit 6 includes a first-stage reverse osmosis membrane concentration system, a second-stage reverse osmosis membrane concentration system, and an evaporation concentration system connected in sequence.

[0083] Lithium adsorption tower 2 has a pretreatment gas field water inlet, a desorption solvent inlet (for introducing the desorption solvent), a lithium-containing solution outlet, and an adsorption tailwater outlet;

[0084] The pretreatment gas field water inlet of lithium adsorption tower 2 is connected to the discharge port of filter device 1;

[0085] The lithium-containing solution outlet of lithium adsorption tower 2 is connected to the feed inlet of concentration device 6;

[0086] The inlet of the precipitation reaction device 7 is connected to the outlet of the concentration device 6, and the precipitation reaction device 7 has a carbonate inlet.

[0087] (3) The bromine extraction unit includes a reaction tank 3, a stripping tower 4, and an absorption tower 5; among which...

[0088] The feed inlet of reaction vessel 3 is connected to the adsorption tailwater outlet of lithium adsorption tower 2;

[0089] Reaction vessel 3 has an acid inlet and a chlorine inlet;

[0090] The discharge port of reaction vessel 3 is connected to the feed port at the top of stripping tower 4, and an air inlet is provided at the bottom of stripping tower 4;

[0091] The feed inlet of the absorption tower 5 is connected to the discharge outlet at the top of the stripping tower 4; sulfur dioxide is installed inside the absorption tower 5.

[0092] (II) This embodiment provides a method for recovering water resources in a gas field, such as... Figure 2 As shown, it includes the following steps:

[0093] Gas field water with lithium ion content of 80 mg / L, bromide ion content of 100 ppm, oil content of 2 mg / L, TOC content of 10 mg / L, sulfate content of 30 mg / L, magnesium ion content of 0.28 g / L, and chloride ion content of 12 g / L was pumped into filtration device 1 (ultrafiltration membrane system, with an average pore size of 0.1 μm and a molecular weight cutoff of 20,000 Da) to remove suspended solids and oily substances. Under a pressure of 0.2 MPa, the turbidity of the effluent was <1 NTU.

[0094] The effluent from the filtration device 1 (ultrafiltration membrane system) is pumped into the lithium adsorption tower 2 (filled with JW-LAHS-03 aluminum-based adsorbent) for lithium adsorption. The influent flow rate is 10 BV / h. After adsorption, desorption is performed (soft water with a TDS value of 100 mg / L is used as the desorption solvent). The desorption influent flow rate is 10 BV / h, the desorption water temperature is 40℃, and the lithium content in the desorbed lithium-containing solution is 190 mg / L. The lithium concentration in the adsorption tail water is 12.8 mg / L.

[0095] The lithium-containing solution undergoes preliminary lithium concentration in the first-stage reverse osmosis membrane concentration system of concentration unit 6 (operating pressure 3.0–3.5 MPa), yielding a first-stage reverse osmosis membrane concentrate (with a lithium recovery rate of 95%, i.e., the weight content of lithium in the first-stage reverse osmosis membrane concentrate / the weight content of lithium in the lithium-containing solution × 100%) and a first-stage reverse osmosis membrane permeate. The first-stage reverse osmosis membrane concentrate further enters the second-stage reverse osmosis membrane concentration system for deep concentration (operating pressure 7.5–8.0 MPa), yielding a second-stage reverse osmosis membrane concentrate (with a lithium recovery rate of 72%, i.e., the weight content of lithium in the second-stage reverse osmosis membrane concentrate / the weight content of lithium in the first-stage reverse osmosis membrane concentrate × 100%) and a second-stage reverse osmosis membrane permeate. The second-stage reverse osmosis membrane concentrate enters the evaporation concentration system for further concentration, yielding a lithium-rich solution with a lithium content of 22.8 g / L. The first-stage and second-stage membrane permeates are refluxed as desorption solvents.

[0096] The lithium-rich solution enters the precipitation reaction device 7, and a sodium carbonate aqueous solution with a sodium carbonate mass concentration of 20% is added to precipitate lithium carbonate. The product is washed and centrifuged to obtain lithium carbonate with a purity of 99.6% and a lithium yield of 72% (i.e., the weight of lithium carbonate product / the weight content of lithium in the raw gas field water × 100%).

[0097] The adsorption tailwater enters reaction tank 3 for acidification treatment (pH value 2-4) to obtain acidified gas field water. Chlorine gas is then introduced into reaction tank 3 for oxidation reaction to obtain oxidized liquid. The amount of chlorine gas introduced is 120% of the chlorine ratio of the bromine-chlorine reaction.

[0098] The oxidizing liquid enters from the top of the stripping tower 4 and is sprayed downwards. Bromine molecules in the oxidizing liquid are stripped by air flowing upwards inside the stripping tower, forming gaseous bromine, which is then blown out from the top of the stripping tower 4 and enters the absorption tower 5. The purity of the gaseous bromine is 99.3%, and the bromine recovery rate is 84% ​​(i.e., (bromine ion content in the raw gas field water - bromide ion content in the oxidizing liquid after oxidizing and stripping) / bromide ion content in the raw gas field water × 100%).

[0099] Example 4

[0100] (I) This embodiment provides a gas field water resource recovery system, such as Figure 1 As shown, it includes a pretreatment unit, a lithium extraction unit, and a bromine extraction unit connected in sequence; wherein,

[0101] (1) The pretreatment unit includes a filtration device 1, which is an ultrafiltration membrane system;

[0102] (2) The lithium extraction unit includes a lithium adsorption tower 2, a concentration device 6, and a precipitation reaction device 7.

[0103] The concentration unit 6 includes a first-stage reverse osmosis membrane concentration system, a second-stage electrodialysis membrane concentration system, and an evaporation concentration system connected in sequence.

[0104] Lithium adsorption tower 2 has a pretreatment gas field water inlet, a desorption solvent inlet (for introducing the desorption solvent), a lithium-containing solution outlet, and an adsorption tailwater outlet;

[0105] The pretreatment gas field water inlet of lithium adsorption tower 2 is connected to the discharge port of filter device 1;

[0106] The lithium-containing solution outlet of lithium adsorption tower 2 is connected to the feed inlet of concentration device 6;

[0107] The inlet of the precipitation reaction device 7 is connected to the outlet of the concentration device 6, and the precipitation reaction device 7 has a carbonate inlet.

[0108] (3) The bromine extraction unit includes a reaction tank 3, a stripping tower 4, and an absorption tower 5; among which...

[0109] The feed inlet of reaction vessel 3 is connected to the adsorption tailwater outlet of lithium adsorption tower 2;

[0110] Reaction vessel 3 has an acid inlet and a chlorine inlet;

[0111] The discharge port of reaction vessel 3 is connected to the feed port at the top of stripping tower 4, and an air inlet is provided at the bottom of stripping tower 4;

[0112] The feed inlet of the absorption tower 5 is connected to the discharge outlet at the top of the stripping tower 4; sulfur dioxide is installed inside the absorption tower 5.

[0113] (II) This embodiment provides a method for recovering water resources in a gas field, such as... Figure 2 As shown, it includes the following steps:

[0114] Gas field water with a lithium ion content of 100 mg / L, a bromide ion content of 200 ppm, an oil content of 2 mg / L, a TOC content of 10 mg / L, a sulfate content of 30 mg / L, a magnesium ion content of 0.26 g / L, and a chloride ion content of 10 g / L was pumped into filtration device 1 (ultrafiltration membrane system, with an average pore size of 0.1 μm and a molecular weight cutoff of 200,000 Da) to remove suspended solids and oily substances. Under a pressure of 0.2 MPa, the turbidity of the effluent was <1 NTU.

[0115] After adjusting the pH of the effluent from filter device 1 (ultrafiltration membrane system) to 12 (pH adjustment was performed here because titanium-based adsorbents are more suitable for alkaline conditions), the effluent is pumped into lithium adsorption tower 2 (filled with JW-LTOS-03 titanium-based adsorbent) for lithium adsorption. The influent flow rate is 5 BV / h. After adsorption, desorption is performed (soft water with a TDS value of 110 mg / L is used as the desorption solvent). The influent flow rate for desorption is 4 BV / h, and the desorption water temperature is 40℃. The lithium content in the desorbed lithium-containing solution is 160 mg / L, and the lithium concentration in the adsorption tail water is 22.8 mg / L.

[0116] The lithium-containing solution undergoes preliminary lithium concentration in the first-stage reverse osmosis membrane concentration system of concentration unit 6 (operating pressure 3.0–3.5 MPa), yielding a first-stage reverse osmosis membrane concentrate (with a lithium recovery rate of 95%, i.e., the weight content of lithium in the first-stage reverse osmosis membrane concentrate / the weight content of lithium in the lithium-containing solution × 100%) and a first-stage reverse osmosis membrane permeate. The first-stage reverse osmosis membrane concentrate further enters the second-stage electrodialysis membrane concentration system for deep concentration (current efficiency of 71%), yielding a second-stage reverse osmosis membrane concentrate (with a lithium recovery rate of 72%, i.e., the weight content of lithium in the second-stage reverse osmosis membrane concentrate / the weight content of lithium in the first-stage reverse osmosis membrane concentrate × 100%) and a second-stage reverse osmosis membrane permeate. The second-stage reverse osmosis membrane concentrate enters the evaporation concentration system for further concentration, yielding a lithium-rich solution with a lithium content of 23 g / L. The first-stage membrane permeate is refluxed as a desorption solvent, and the second-stage membrane permeate is refluxed back to the first-stage reverse osmosis membrane concentration system.

[0117] The lithium-rich solution enters the precipitation reaction device, and a sodium carbonate aqueous solution with a mass concentration of 20% is added to precipitate lithium carbonate. The product is washed and centrifuged to obtain lithium carbonate with a purity of 99.2% and a lithium yield of 74% (i.e., the weight of lithium carbonate product / the weight content of lithium in the raw gas field water × 100%).

[0118] The adsorption tailwater enters reaction tank 3 for acidification treatment (pH value 2-4) to obtain acidified gas field water. Chlorine gas is then introduced into reaction tank 3 for oxidation reaction to obtain oxidized liquid. The amount of chlorine gas introduced is 110% of the chlorine ratio of the bromine-chlorine reaction.

[0119] The oxidizing liquid enters from the top of the stripping tower 4 and is sprayed downwards. Bromine molecules in the oxidizing liquid are stripped by air flowing upwards inside the stripping tower, yielding gaseous bromine, which is then blown out from the top of the stripping tower 4 and enters the absorption tower 5. The purity of the gaseous bromine is 99.6%, and the bromine yield is 85% (i.e., the bromide ion content in the oxidizing liquid after oxidizing and stripping / the bromide ion content in the raw gas field water × 100%).

[0120] Example 5

[0121] (I) This embodiment provides a gas field water resource recovery system, such as Figure 1 As shown, it includes a pretreatment unit, a lithium extraction unit, and a bromine extraction unit connected in sequence; wherein,

[0122] (1) The pretreatment unit includes a filtration device 1, which is an ultrafiltration membrane system;

[0123] (2) The lithium extraction unit includes a lithium adsorption tower 2, a concentration device 6, and a precipitation reaction device 7.

[0124] The concentration unit 6 includes a first-stage reverse osmosis membrane concentration system, a second-stage electrodialysis membrane concentration system, and an evaporation concentration system connected in sequence.

[0125] Lithium adsorption tower 2 has a pretreatment gas field water inlet, a desorption solvent inlet (for introducing the desorption solvent), a lithium-containing solution outlet, and an adsorption tailwater outlet;

[0126] The pretreatment gas field water inlet of lithium adsorption tower 2 is connected to the discharge port of filter device 1;

[0127] The lithium-containing solution outlet of lithium adsorption tower 2 is connected to the feed inlet of concentration device 6;

[0128] The inlet of the precipitation reaction device 7 is connected to the outlet of the concentration device 6, and the precipitation reaction device 7 has a carbonate inlet.

[0129] (3) The bromine extraction unit includes a reaction tank 3, a stripping tower 4, and an absorption tower 5; among which...

[0130] The feed inlet of reaction vessel 3 is connected to the adsorption tailwater outlet of lithium adsorption tower 2;

[0131] Reaction vessel 3 has an acid inlet and a chlorine inlet;

[0132] The discharge port of reaction vessel 3 is connected to the feed port at the top of stripping tower 4, and an air inlet is provided at the bottom of stripping tower 4;

[0133] The feed inlet of the absorption tower 5 is connected to the discharge outlet at the top of the stripping tower 4; sulfur dioxide is installed inside the absorption tower 5.

[0134] (II) This embodiment provides a method for recovering water resources in a gas field, such as... Figure 2 As shown, it includes the following steps:

[0135] Gas field water with a lithium ion content of 95 mg / L, a bromide ion content of 800 ppm, an oil content of 5 mg / L, a TOC content of 10 mg / L, a sulfate content of 30 mg / L, a magnesium ion content of 0.33 g / L, and a chloride ion content of 10 g / L was pumped into filtration device 1 (ultrafiltration membrane system, with an average pore size of 0.05 μm and a molecular weight cutoff of 5,000,000 Da) to remove suspended solids and oily substances. Under a pressure of 0.2 MPa, the turbidity of the effluent was <1 NTU.

[0136] The effluent from the filtration unit 1 (ultrafiltration membrane system) is pumped into the lithium adsorption tower 2 (filled with JW-LAHS-03 aluminum-based adsorbent) for lithium adsorption. The influent flow rate is 8 BV / h. After adsorption, desorption is performed (soft water with a TDS value of 120 mg / L is used as the desorption solvent). The influent flow rate for desorption is 6 BV / h, and the desorption water temperature is 40℃. The lithium content in the desorbed lithium-containing solution is 150 mg / L, and the lithium concentration in the adsorption tail water is 23.15 mg / L.

[0137] The lithium-containing solution undergoes preliminary lithium concentration in the first-stage reverse osmosis membrane concentration system of concentration unit 6 (operating pressure 3.0–3.5 MPa), yielding a first-stage reverse osmosis membrane concentrate (with a lithium recovery rate of 95%, i.e., the weight content of lithium in the first-stage reverse osmosis membrane concentrate / the weight content of lithium in the lithium-containing solution × 100%) and a first-stage reverse osmosis membrane permeate. The first-stage reverse osmosis membrane concentrate further enters the second-stage electrodialysis membrane concentration system for deep concentration (current efficiency of 64%), yielding a second-stage reverse osmosis membrane concentrate (with a lithium recovery rate of 72%, i.e., the weight content of lithium in the second-stage reverse osmosis membrane concentrate / the weight content of lithium in the first-stage reverse osmosis membrane concentrate × 100%) and a second-stage reverse osmosis membrane permeate. The second-stage reverse osmosis membrane concentrate enters the evaporation concentration system for further concentration, yielding a lithium-rich solution with a lithium content of 23 g / L. The first-stage membrane permeate is refluxed as a desorption solvent, and the second-stage membrane permeate is refluxed back to the first-stage reverse osmosis membrane concentration system.

[0138] The lithium-rich solution enters the precipitation reaction device, and a sodium carbonate aqueous solution with a mass concentration of 20% is added to precipitate lithium carbonate. The product is washed and centrifuged to obtain lithium carbonate with a purity of 98.6% and a lithium yield of 73% (i.e., the weight of lithium carbonate product / the weight content of lithium in the raw gas field water × 100%).

[0139] The adsorption tailwater enters reaction tank 3 for acidification treatment (pH value 2-4) to obtain acidified gas field water. Chlorine gas is then introduced into reaction tank 3 for oxidation reaction to obtain oxidized liquid. The amount of chlorine gas introduced is 130% of the chlorine ratio of the bromine-chlorine reaction.

[0140] The oxidizing liquid enters from the top of the stripping tower 4 and is sprayed downwards. Bromine molecules in the oxidizing liquid are stripped by air flowing upwards within the stripping tower, forming air containing bromine molecules. This air is then blown out from the top of the stripping tower 4 and enters the absorption tower 5, yielding gaseous bromine. The purity of the gaseous bromine is 99.7%, and the bromine yield is 87% (i.e., (bromine ion content in the raw gas field water - bromide ion content in the oxidizing liquid after oxidative stripping) / bromide ion content in the raw gas field water × 100%).

Claims

1. A method for recovering water resources in a gas field, wherein, Includes the following steps: Pretreatment steps: The gas field water is subjected to media filtration and / or ultrafiltration membrane filtration to obtain pretreated gas field water; Lithium extraction steps: The pretreated gas field water is subjected to lithium adsorption using a lithium adsorbent to obtain adsorbed tail water; and after the lithium adsorption, the lithium adsorbent is desorbed to obtain a lithium-containing solution. Bromine extraction steps: The adsorbed tail water is subjected to acidification and oxidation treatment in sequence to obtain an oxidized liquid; the oxidized liquid is then subjected to air stripping to obtain gaseous bromine.

2. The gas field water resource recovery method according to claim 1, wherein, The media used for filtration include quartz sand filter media and / or activated carbon; and / or, The ultrafiltration membrane used in the ultrafiltration process has an average pore size of 0.002–0.5 μm; and / or The ultrafiltration membrane used in the ultrafiltration process has a molecular weight cutoff of 10,000 to 5,000,000 Da.

3. The gas field water resource recovery method according to claim 1, wherein, The ultrafiltration membrane used in the ultrafiltration process has an average pore size of 0.05–0.1 μm; and / or The ultrafiltration membrane used in the ultrafiltration process has a molecular weight cutoff of 20,000 to 5,000,000 Da.

4. The gas field water resource recovery method according to claim 1, wherein, The adsorption flow rate during the lithium adsorption process is 1–20 BV / h; the desorption flow rate during the lithium desorption process is 1–30 BV / h.

5. The gas field water resource recovery method according to claim 1, wherein, The adsorption flow rate during the lithium adsorption process is 5–15 BV / h; the desorption flow rate during the lithium desorption process is 4–12 BV / h.

6. The gas field water resource recovery method according to claim 1, wherein, The lithium adsorbent is selected from one or more of aluminum-based adsorbents, manganese-based adsorbents, and titanium-based adsorbents.

7. The gas field water resource recovery method according to claim 1, wherein, The lithium adsorbent is selected from aluminum-based adsorbents and / or titanium-based adsorbents; The adsorption component of the aluminum-based adsorbent is lithium aluminum layered double hydroxide; The adsorption component of the titanium-based adsorbent is a spinel-type titanium oxide ion sieve.

8. The gas field water resource recovery method according to claim 1, wherein, The recycling method further includes the following steps: Concentration step: The lithium-containing solution is concentrated to obtain a lithium-rich solution; Precipitation step: Add carbonate to the lithium-rich solution to carry out a precipitation reaction to obtain lithium carbonate; Absorption step: The gaseous bromine is absorbed by an aqueous solution of sulfur dioxide to obtain hydrobromic acid.

9. The gas field water resource recovery method according to claim 8, wherein, The concentration method is reverse osmosis membrane concentration and / or electrodialysis membrane concentration.

10. The gas field water resource recovery method according to claim 9, wherein, The concentration includes sequentially performed first-stage membrane concentration, second-stage membrane concentration, and evaporative concentration; The first-stage membrane concentration is a first-stage reverse osmosis membrane concentration; the second-stage membrane concentration is a second-stage reverse osmosis membrane concentration or a second-stage electrodialysis membrane concentration. The operating pressure of the first-stage reverse osmosis membrane concentration is 3.0–3.5 MPa, the operating pressure of the second-stage reverse osmosis membrane concentration is 7.5–8.0 MPa, and the current efficiency of the second-stage electrodialysis membrane concentration is 64–71%.

11. The gas field water resource recovery method according to claim 1, wherein, The oxidant used in the oxidation treatment is chlorine gas, and the amount of chlorine gas introduced is 110-140% of the chlorine ratio in the bromine-chlorine reaction; and / or, during the acidification treatment, acid is added to the system to control the pH value of the system to be 2-4.

12. The gas field water resource recovery method according to claim 1, wherein, The gas field water has the following characteristics: COD 1–300 ppm; TOC 1–100 ppm; oily substance content 1–100 ppm; lithium ion content 10–300 ppm; bromide ion content 100–800 ppm; magnesium ion content 0.1–1.0 g / L; sulfate ion content 1–300 ppm; and pH value 5–9.

13. A gas field water resource recovery system, wherein, Includes a pretreatment unit, a lithium extraction unit, and a bromine extraction unit; The pretreatment unit includes a media filtration device and / or an ultrafiltration membrane filtration device; The lithium extraction unit includes a lithium adsorption tower; The bromine extraction unit includes a reaction vessel and a stripping tower; The lithium adsorption tower has a pretreated gas field water inlet, a desorption solvent inlet, a lithium-containing solution outlet, and an adsorption tailwater outlet; the pretreated gas field water inlet is connected to the outlet of the pretreated unit; the inlet of the reaction tank is connected to the adsorption tailwater outlet; the reaction tank also has an acid feed inlet and an oxidant feed inlet; the inlet at the top of the stripping tower is connected to the outlet of the reaction tank; and the bottom of the stripping tower has an air inlet, and the top has a gaseous bromine outlet.

14. The gas field water resource recovery system according to claim 13, wherein, The lithium extraction unit also includes a concentration device and a precipitation reaction device; The feed inlet of the concentration device is connected to the lithium-containing solution outlet of the lithium adsorption tower; The inlet of the precipitation reaction device and the outlet of the concentration device are connected; the precipitation reaction device has a carbonate feed port.

15. The gas field water resource recovery system according to claim 14, wherein, The concentration device includes a first-stage membrane concentration device, a second-stage membrane concentration device, and an evaporation concentration device connected in sequence; the membrane in the first-stage membrane concentration device is a reverse osmosis membrane; the membrane in the second-stage membrane concentration device is a reverse osmosis membrane or an electrodialysis membrane.

16. The gas field water resource recovery system according to claim 13, wherein, The bromine extraction unit also includes an absorption tower; the inlet of the absorption tower is connected to the gaseous bromine outlet at the top of the stripping tower; and sulfur dioxide is provided inside the absorption tower.

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