Gas field water up-to-standard discharge treatment device

Abstract

The utility model provides a gas field water up-to-standard discharge treatment device, and relates to the technical field of sewage treatment. The device comprises a first unit, a second unit and a third unit, wherein the first unit comprises a sulfur removal assembly and a microelectrolysis-Fenton assembly; the treated water enters a second unit, and the sludge I enters a fourth unit; the second unit comprises a filtering assembly, concentrated water, fresh water and second sludge are obtained, the concentrated water enters the third unit, and the second sludge enters the fourth unit; the third unit comprises a crystallization assembly and an MBR membrane assembly; crystalline salt, residual sludge and clear water are obtained, and the residual sludge enters a fourth unit; the fourth unit comprises a solid waste assembly, and mud cakes and squeezed water are obtained. According to the treatment device provided by the utility model, the removal effect on organic matters in gas field water is enhanced, so that the service life of a membrane separation system is prolonged. The two-stage micro-electrolysis tank is adopted to forcibly oxidize the pre-oxidized gas field water again, 'ring opening and chain scission 'are carried out on refractory organics, most of the organics are removed in the first unit, the water inlet load of a membrane separation system in the subsequent second unit is reduced, and the service life of a semipermeable membrane is effectively prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of sewage treatment, in particular to a gas field water discharge treatment device that meets the standards. Background Art

[0002] During the exploration and development of natural gas in gas fields, fracturing fluid is often used to fractur e oil and gas reservoirs to ensure normal natural gas production. However, a large amount of fracturing flowback fluid will be produced during the fracturing operation, and a large amount of formation water will also be brought out. This water returning to the ground is collectively referred to as gas field water. Affected by the formation, geology, and drilling technology, the water quality characteristics of gas field water in different blocks vary greatly, and generally have the following characteristics: ①Cl - On average, 5×10 4 mg / L, the gas field water is weakly acidic; ② The content of organic matter such as petroleum is high, among which COD can reach several thousand or even tens of thousands of mg / L; ③ The total mineralization is relatively high, reaching tens of thousands to hundreds of thousands of mg / L; ④ There is dissolved H 2 S and other harmful gases. Since the gas field water contains more complex substances, if it is not effectively treated, it will cause serious pollution to the environment.

[0003] At present, the treatment methods for gas field water mainly include reinjection into the formation after pretreatment, reuse and preparation of chemicals after pretreatment, and discharge after deep treatment. Since the pretreatment method does not treat the gas field water thoroughly, it will affect the development and operation of the gas field. In addition, the current treatment method also has the problem of high consumption of chemicals and high costs. Utility Model Content

[0004] The purpose of the utility model is to provide a gas field water discharge treatment device that meets the standards and can efficiently remove H 2 S.COD Cr 、BOD 5 , SS and a large number of pollutants such as chloride ions, calcium and magnesium ions, so as to ensure that the gas field water meets the discharge standards. The specific contents are as follows:

[0005] The utility model provides a gas field water discharge treatment device that meets the standards, comprising

[0006] The first unit includes a desulfurization component and a micro-electrolysis-Fenton component; sludge 1 and treated water are obtained, the treated water enters the second unit, and the sludge 1 enters the fourth unit;

[0007] The second unit includes a filtering assembly to obtain concentrated water, fresh water and sludge 2, the concentrated water enters the third unit, and the sludge 2 enters the fourth unit;

[0008] The third unit includes a crystallization component and an MBR membrane component; crystallized salt, excess sludge and clean water are obtained, and the excess sludge enters the fourth unit;

[0009] The fourth unit, which includes the solid waste component, obtains mud cake and press water.

[0010] According to an optional implementation, the gas field water enters the regulating tank and then enters the first unit.

[0011] According to an optional embodiment, the squeeze water is passed into a regulating tank.

[0012] According to an optional embodiment, the desulfurization component is a dosing desulfurization tank, in which NaClO, ZnSO 4 Before entering the micro-electrolysis cell, adjust the pH value to 3-4. The micro-electrolysis-Fenton component includes a first-level micro-electrolysis cell, a second-level micro-electrolysis cell, and an inclined plate sedimentation tank connected in sequence. The first-level micro-electrolysis cell is provided with a reagent input port (i.e., H 2 SO 4 、NaHSO 3 ), the secondary micro-electrolysis cell is equipped with a reagent input port (i.e. H 2 O 2 ).

[0013] According to an optional embodiment, the filtration component includes a tubular microfiltration membrane, a nanofiltration membrane, and a two-stage reverse osmosis membrane; the sludge obtained by the tubular microfiltration membrane enters the fourth unit, the concentrated water obtained by the nanofiltration membrane is returned to the gas field water pretreatment unit, the concentrated water obtained by the two-stage reverse osmosis membrane enters the third unit, and the fresh water obtained by the two-stage reverse osmosis membrane enters the clear water tank.

[0014] According to an optional embodiment, the crystallization unit is an MVR evaporator, and the MBR membrane assembly is an MBR membrane bioreactor.

[0015] According to an optional embodiment, the solid waste component includes a sludge thickening tank, a filter press, and squeezed water obtained by the filter press. After the sludge is concentrated, a PAM cation is added.

[0016] The technical solution of the embodiment of the utility model has at least the following advantages and beneficial effects:

[0017] 1. The treatment device provided by the utility model enhances the removal effect of organic matter in gas field water, thereby extending the service life of the membrane separation system. A two-stage micro-electrolysis cell is used to force oxidation of the pre-oxidized gas field water again, and the difficult-to-degrade organic matter is "opened and broken". Most of the organic matter is removed in the first unit, reducing the water inlet load of the membrane separation system in the subsequent second unit, and effectively extending the service life of the semipermeable membrane.

[0018] 2. The treatment device provided by the utility model effectively reduces the amount of reagents used by designing the dosing reaction process of the first unit. ① Using NaClO and H 2 The H generated by the reaction of S 2 SO 3 , H2 SO 4 The products such as sulphur removal can reduce the pH value of the raw water after desulfurization, thereby reducing the amount of H in the water entering the micro-electrolysis cell. 2 SO 4 ② Since Fe has been generated at the anode of the micro-electrolysis cell, 2+ , and the pH of the influent is acidic, so only H 2 O 2 The reagent can form a combined treatment process of "iron-carbon micro-electrolysis-Fenton method", and basically no FeSO 4 The oxidation performance of the micro-electrolytic cell can be enhanced. ③ At the end of the micro-electrolytic cell, after the Fenton reaction, part of the Fe 2+ Oxidized to Fe 3+ , Fe 2+ , Fe 3+ They all have extremely strong hydrolysis ability. After adjusting the pH value to alkaline with NaOH, they can generate ferrous hydroxide and ferric hydroxide colloidal flocculants. Their coagulation effect is much higher than that of general coagulants. Therefore, there is no need to add other coagulants to complete solid-liquid separation in the inclined plate sedimentation tank.

[0019] 3. The treatment device provided by the utility model adopts a two-stage reverse osmosis membrane to treat raw water. The water inlet end of the second-stage reverse osmosis membrane is connected to the water production end of the fresh water side of the first-stage reverse osmosis membrane, thereby enhancing the membrane separation effect and effectively ensuring that the effluent water quality meets the discharge standards.

[0020] 4. The treatment device provided by the utility model uses an MBR membrane bioreactor to treat the condensed water produced by the MVR evaporator. Since the refractory organic matter in the raw water has completed the "open-loop chain breaking", the BOD in the condensed water is effectively improved. 5 / COD cr value, and has the conditions for biochemical treatment. This device uses high-concentration activated sludge in the reactor to oxidize the organic matter in the condensed water. Compared with the ordinary activated sludge method, this device can complete the mud-water separation without the need for a secondary sedimentation tank, reducing the equipment footprint; compared with the dosing oxidation method, this device can complete the oxidation of organic matter in the condensed water without the need for adding strong oxidizing agents. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the connection of a gas field water discharge treatment device that meets the standards provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0026] In the description of the present invention, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the application is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0027] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] Example 1

[0029] This embodiment provides a gas field water discharge treatment device that meets the standards, which specifically includes a first unit, a second unit, a third unit and a fourth unit that are connected in sequence.

[0030] <Preprocessing>

[0031] After the gas field water enters the regulating tank, it is homogenized and equalized to provide relatively stable conditions for subsequent processing. The regulating tank is an underground reinforced concrete structure. Under the control of the liquid level controller in the regulating tank, the raw water is quantitatively lifted into the first unit through the lifting pump.

[0032] <Unit 1>

[0033] Complete pretreatment of gas field water to remove H 2 S, SS, CODcr and Mg 2+ , Ca 2+ , reducing the processing load of subsequent processing units.

[0034] The raw water first enters the dosing desulfurization tank and reacts with NaClO, ZnSO 4 After thorough mixing, the H 2 S is oxidized and replaced with sulfate and zinc sulfide, and some organic matter is removed in advance. The reaction also generates H 2 SO 3 , H 2 SO 4 , acidify the raw water quality; the desulfurized raw water enters the two-stage micro-electrolysis cell, and H is selectively added depending on the pH value of the inlet water. 2 SO 4 Adjust the pH value of the influent to 3-4 and add NaHSO 3 In the two-stage iron-carbon micro-electrolysis cell (i.e., micro-electrolysis cell), the cathode carbon particles of the micro-electrolysis filler and the anode iron filings generate a tiny current, which, under the action of aeration, produces highly oxidizing H 2 O 2 and hydroxyl radicals to degrade organic matter in water. At the same time, H 2 O 2 , forming an iron-carbon micro-electrolysis-Fenton process to strengthen the oxidation of organic matter in the water and convert the Fe 2+ Ions are oxidized to Fe 3+ ions. After the raw water has completed efficient oxidation to remove organic matter, before entering the inclined plate sedimentation tank, NaOH is used to adjust the raw water pH value to above 10. 3+ Ionic hydrates have strong adsorption and flocculation activity. After adding alkali, they can generate iron hydroxide colloidal flocculants, which can absorb a large amount of tiny suspended solids, metal particles and organic macromolecules dispersed in water. At the same time, NaCO 3 After fully reacting with the raw water, the Mg in the raw water 2+ , Ca 2+ The precipitate is produced, so that the suspended matter, metal particles, organic macromolecules and calcium and magnesium precipitates are separated into solid and liquid in the inclined plate sedimentation tank, achieving the purpose of deturbidity and softening the raw water.

[0035] <Unit 2>

[0036] The raw water after treatment in the first unit is deeply treated, the monovalent and divalent ions in the water are effectively separated, and the salt in the raw water is intercepted to ensure that the effluent meets the discharge standards.

[0037] After being treated in the first unit, the effluent enters the second unit for deep treatment. The raw water first enters the tubular microfiltration membrane TMF, where the interception effect of the membrane is used to filter fine suspended solids, reducing the interception load of the subsequent semi-permeable membrane precision filtration system. The effluent from the tubular microfiltration membrane enters the nanofiltration membrane and the two-stage reverse osmosis membrane in turn, where the selective permeability of the membrane is used to further effectively separate the monovalent and divalent ions in the water, and the salt in the raw water is intercepted to form concentrated water. The concentrated water from the nanofiltration membrane flows back to the regulating tank and is circulated and treated with gas field water again. The concentrated water produced by the two-stage reverse osmosis membrane enters the third unit for treatment, and the fresh water on the water production side of the second-stage reverse osmosis membrane meets the discharge standards after being tested and qualified.

[0038] Among them, the roll nanofiltration unit: recovery rate R ≥ 75% (after three years of operation); divalent ion removal rate (MgSO 4 Calculated) D≥97%.

[0039] Roll-type reverse osmosis unit: primary reverse osmosis recovery rate R1 ≥ 50% (after three years of operation); primary reverse osmosis desalination rate (in terms of NaCl) D1 ≥ 98%; secondary reverse osmosis recovery rate R2 ≥ 75% (after three years of operation); secondary reverse osmosis desalination rate (in terms of NaCl) D2 ≥ 98%.

[0040] <Unit 3>

[0041] The concentrated water produced by the reverse osmosis unit of the second unit is treated with evaporation and crystallization to ensure that the salt crystals are completely separated. The evaporated condensed water is oxidized using the activated sludge method to ensure that the condensed water meets the discharge standards.

[0042] The third unit mainly treats the concentrated water produced by the reverse osmosis unit (i.e., two-stage reverse osmosis membrane) in the second unit. The concentrated water enters the MVR evaporator and is evaporated and crystallized through multiple heat exchanges. The separated solid crystal salt is transported out. Since the liquid condensed water still contains some organic matter, the condensed water enters the biochemical treatment unit (MBR membrane assembly) and is oxidized by activated sludge. The remaining sludge produced by the biochemical treatment unit and the sludge in the inclined plate sedimentation tank in the first unit are pumped into the fourth unit for dehydration treatment.

[0043] <Unit 4>

[0044] As a solid waste treatment unit, the water-containing sludge produced by the first unit and the fourth unit is dehydrated, the dehydrated mud cake is transported out for disposal, and the separated liquid water is returned to the equalization tank for circulation treatment.

[0045] The fourth unit is mainly used as a solid waste treatment unit. The sludge produced by the first and third units are collected in the sludge thickening tank in the fourth unit to complete gravity concentration. The concentrated sludge is formed into flocs after adding PAM cations and then pumped into the filter press (screw dewatering machine). The sludge is squeezed and dehydrated in the dewatering machine. The dehydrated mud cake is transported out for disposal, and the squeezed water enters the regulating tank for further treatment.

[0046] Among them, sludge thickening tank: gravity thickening, sludge maximum residence time HRT = 3d;

[0047] Screw stack dehydrator: inlet mud moisture content c1 = 95 ~ 99.5%; outlet mud moisture content c2 = 75 ~ 80%.

[0048] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A gas field water discharge treatment device that meets the standards, characterized in that: include The first unit includes a desulfurization component and a micro-electrolysis-Fenton component; sludge 1 and treated water are obtained, the treated water enters the second unit, and the sludge 1 enters the fourth unit; The second unit includes a filtering assembly to obtain concentrated water, fresh water and sludge 2, the concentrated water enters the third unit, and the sludge 2 enters the fourth unit; The third unit includes a crystallization module and an MBR membrane module; Crystallized salt, excess sludge and clean water are obtained, and the excess sludge enters the fourth unit; The fourth unit, which includes the solid waste component, obtains mud cake and press water.

2. The gas field water discharge treatment device according to claim 1 is characterized in that: After the gas field water enters the regulating tank, it enters the first unit.

3. The gas field water discharge treatment device according to claim 2 is characterized in that: The squeezed water is passed into the regulating tank.

4. The gas field water discharge treatment device according to any one of claims 1 to 3, characterized in that: The desulfurization component is a chemical addition desulfurization tank; the micro-electrolysis-Fenton component includes a primary micro-electrolysis tank, a secondary micro-electrolysis tank, and an inclined plate sedimentation tank connected in sequence, and the micro-electrolysis tanks are all provided with a reagent input port.

5. The gas field water discharge treatment device according to any one of claims 1 to 3, characterized in that: The filtration components include tubular microfiltration membrane, nanofiltration membrane, and two-stage reverse osmosis membrane; the sludge obtained from the tubular microfiltration membrane enters the fourth unit, the concentrated water obtained from the nanofiltration membrane flows back to the gas field water pretreatment unit, the concentrated water obtained from the two-stage reverse osmosis membrane enters the third unit, and the fresh water obtained from the two-stage reverse osmosis membrane enters the clear water tank.

6. The gas field water discharge treatment device according to any one of claims 1 to 3, characterized in that: The crystallization unit is an MVR evaporator, and the MBR membrane component is an MBR membrane bioreactor.

7. The gas field water discharge treatment device according to any one of claims 1 to 3, characterized in that: The solid waste components include a sludge thickening tank, a filter press, and the squeezed water obtained from the filter press.

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