Sulfur-containing sewage treatment process and application thereof

Abstract

The invention discloses a sulfur-containing sewage treatment process and application thereof, and belongs to the technical field of sewage treatment. The sulfur-containing sewage treatment process comprises pretreatment and deep treatment, wherein the pretreatment comprises steam stripping treatment and oxidative desulfurization treatment; the pressure of the steam stripping treatment is 0 MPa to 0.050 MPa; a micro-positive pressure steam stripping and oxidative desulfurization process is adopted in the pretreatment stage, clarification pretreatment, ammonia nitrogen removal, COD (Chemical Oxygen Demand) removal, ion removal and other processes are adopted in the advanced treatment stage, and finally, the quality of effluent reaches the standard of reuse water.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a sulfur-containing sewage treatment process in the collection, transportation and purification links during the development of sulfur-containing gas fields. Background Art

[0002] In the process of developing sour gas fields, the production of natural gas will inevitably carry a certain amount of gas field water. As the environmental protection situation becomes increasingly severe and environmental protection requirements gradually increase worldwide, the treatment of sour produced water has become the focus of global attention, especially with the gradual development of sour gas fields such as Puguang and Yuanba. The treatment technology and methods of sour wastewater are also constantly developing, from simple wastewater desulfurization and reinjection to deep treatment and reuse. It has gone through different stages of development and achieved breakthrough progress. The current process steps mainly include desulfurization and deep treatment.

[0003] The desulfurization part is mainly divided into steam stripping and oxidation desulfurization processes. The steam stripping process mainly uses the low solubility of H2S in water to reduce the gas phase partial pressure of H2S with internal combustion engine exhaust gas, air, etc., so that H2S and water are separated. In order to improve the efficiency of steam stripping, the pH value of gas field wastewater should be as low as possible so that sulfide exists in the form of H2S. When the pH of oil and gas field water is less than 5.0, 98% of S 2- It exists in the form of H2S. At this time, the stripping efficiency is the highest. The Weizhou 11-4 Oilfield in the South my country Sea has successfully used the stripping method to treat sulfur-containing wastewater, which greatly reduces the sulfur content of the treated water and can be directly discharged into the sea. The oxidation process is to oxidize sulfide into elemental sulfur and remove it from the sewage. According to the different catalysts, it can be divided into air oxidation and chemical oxidation. Air oxidation is a conventional treatment method that uses oxygen in the air to oxidize organic matter and reducing substances in sewage. The oxidation ability of air is weak. In order to improve the oxidation effect, it must be carried out under certain conditions, such as high temperature, high pressure or the use of catalysts. Considering economics and other aspects, the catalytic oxidation method is currently used in China, that is, under the action of a catalyst, the oxygen in the air is used to oxidize sulfide into thiosulfate or sulfate. The most commonly used catalyst is manganese salt, such as manganese sulfate. In addition, there are metal salts such as copper, iron, cobalt, and activated carbon. A fan and an ultra-microporous releaser are used to carry out strong oxidation in an aeration tank or oxidation tower. Air is filled into the sewage to make it fully contact with the sewage. Harmful gases such as hydrogen sulfide dissolved in the sewage are carried up by a large number of fine bubbles and transferred to the air.

[0004] In 2007, Song Erlian Oily Wastewater Treatment Station carried out a field test on sulfide removal using aeration oxidation desulfurization technology. 2-The average content is below 1 mg / L, but the treatment method has a long reaction time and high energy consumption; the chemical oxidation method removes reducing pollutants in sewage by adding strong oxidants. There are two major types of oxidants commonly used, one is chlorine, such as Cl2, ClO2, NaClO, Ca(ClO)2, etc.; the other is oxygen, such as O2, H2O2, KMnO4. This method should be carried out under alkaline conditions as much as possible to prevent the release of H2S gas during implementation and pollute the atmosphere. The H2O2 method is divided into direct oxidation and catalytic oxidation. The former uses H2O2 for direct desulfurization, and the latter uses Fenton's reagent (H2O2 as an oxidant, Fe 2+ Cu 2+ As a catalyst), catalytic oxidation desulfurization is used, but the effect on the treatment of high-sulfur wastewater is not obvious, and the pH value of the wastewater (3-4) and the concentration of the oxidant must also be controlled. ClO2 has extremely strong oxidizing properties, a wide pH range, a small dosage, and a rapid effect. It is highly favored in the oxidation treatment of sulfur-containing wastewater. The chemical oxidation method is used to treat sulfur-containing wastewater, and the treatment facilities mainly include reaction tanks and sedimentation tanks. When the amount of sewage is not too large, it is usually switched between general oxidation reaction tanks and sedimentation tanks. In Nanyang Oilfield, the oxidation-precipitation method was used to carry out a desulfurization experiment on the sulfur-containing wastewater at Shuanghe Station. After adding homemade oxidizing agents and precipitating agents, S in the water 2- The content dropped from 29.0 mg / L to 0.1 mg / L, meeting the sulfur content requirements of the oilfield reinjection water standard. In addition to the above methods, ozone oxidation and photocatalytic oxidation have also been applied to the project. Because ozone is unstable in aqueous solution, it must be prepared on-site and the processing cost is high. Photocatalytic oxidation is a new water treatment technology that has only appeared in the past 20 years. It can oxidize almost all reducing substances within a certain period of time to avoid secondary pollution. It is a simple, efficient and promising technology. In particular, the catalyst TiO2 immobilization technology overcomes the problem that suspended phase catalysts are difficult to separate and recover in the past, and truly realizes the simultaneous integration of catalysis and separation. The UV-H2O2-TiO2 process was used to treat S 2- It has a good removal effect. Under the conditions of reaction temperature of 30℃ and reaction time of 180min, S 2- The removal rate can reach over 95%.

[0005] The deep treatment process mainly realizes that the wastewater in the pretreatment system stage meets the reuse standard, which mainly includes clarification pretreatment, ammonia nitrogen removal, COD removal, ion removal and other links. At present, Puguang and Yuanba gas fields have adopted this method to make the wastewater in the pretreatment system meet the reuse standard. The main process content is: the gas field water after desulfurization first enters the clarification pretreatment system for softening treatment, and the Ca in the water is 2+ Mg 2+ , Sr 2+The scale-forming ions are removed, and the scale-forming ions are removed to less than 15mg / L after treatment. The clarified water is filtered through the filter and then enters the pre-evaporation system for evaporation treatment to remove ammonia nitrogen and part of COD in the water. The temperature at the bottom of the deamination tower in the pre-evaporation process is controlled at 103-105℃, and the temperature at the top of the tower is 85-95℃. The ammonia nitrogen in the deamination tower inlet is less than 150mg / L, and the ammonia nitrogen in the outlet is less than 10mg / L. The effluent of the deamination tower is transported to the subsequent low-temperature multi-effect evaporation system through a transfer pump. The low-temperature multi-effect evaporation uses a three-effect decompression evaporation process to remove COD from gas field water. This process mainly removes COD. The third effect produces a salt slurry with a solid-liquid ratio of about 15% to 20%, which enters the subsequent drying salt making system for salt making. The COD of the effluent from the low-temperature multi-effect evaporation system is ≤900mg / L. The effluent from the low-temperature multi-effect evaporation system enters the Fenton oxidation device. After treatment by the Fenton oxidation device, the effluent COD is ≤100mg / L and the volatile phenol is ≤0.5mg / L. The effluent from the Fenton device enters the double membrane system for treatment. After treatment, the effluent meets the water quality requirements for supplementary water in the circulating cooling water system of the purification plant. COD mother liquor and deamination tower condensate will be produced during the production process, of which the COD mother liquor output is generally 4% to 5% of the treated water volume. The amount of deamination tower condensate is related to the tower top temperature. The COD mother liquor and deamination tower condensate are finally reinjected into the Yuanba gas field for treatment.

[0006] The above methods have treated the sulfur-containing gas field water to a certain extent and achieved the goal of zero emission. However, a series of problems were exposed during the operation, which not only affected the production operation but also increased the operating cost. These problems mainly include less sulfide removal in the desulfurization stage, easy scaling and clogging of the heat exchange equipment in the deamination tower, extremely high COD of the water inlet of the water treatment system, and difficulty in cleaning the fouling in the double membrane system. At the same time, the application scope of this treatment process is relatively single, and it can only carry out targeted treatment of the sulfur-containing wastewater in the collection and transportation system, and cannot comprehensively consider the integrated treatment of the sulfur-containing wastewater in the collection, transportation and purification system.

[0007] Therefore, it is necessary to optimize the entire sulfur-containing wastewater treatment process to meet the needs of integrated treatment of sulfur-containing wastewater in the collection, transportation and purification systems, and achieve the green and environmentally friendly goal of no acid gas leaving the station. Summary of the invention

[0008] In view of the above situation, the present invention provides a sulfur-containing wastewater treatment process, which is mainly aimed at the integrated construction of collection, transportation and purification, and the need for desulfurization on the same platform, while meeting the needs of sulfur-containing wastewater treatment in the collection, transportation and purification systems, and ultimately making the sulfur-containing wastewater meet the resource utilization standards of public units and achieve the goal of zero emissions.

[0009] In order to solve the above technical problems, the first aspect of the present invention provides a sulfur-containing wastewater treatment process, including pretreatment and deep treatment, the pretreatment includes steam stripping and oxidative desulfurization; the pressure of the steam stripping is 0MPa to 0.05MPa; the sulfide concentration in the pretreated sulfur-containing wastewater is ≤10mg / L;

[0010] The oxidative desulfurization is carried out in a pressure inclined plate tank.

[0011] According to some embodiments of the present invention, the stripping is carried out in a nitrogen stripping tower, and the amount of nitrogen introduced into the nitrogen stripping tower is 8 to 10 times the amount of the sulfur-containing wastewater introduced;

[0012] And / or, a pH regulator is added before the stripping, wherein the pH regulator is hydrochloric acid with a mass concentration of 10%; preferably, the pH regulator is added to adjust the pH to 4.5-5.5, preferably 5.0;

[0013] And / or, a catalyst is added after the stripping, wherein the catalyst is a sodium hydroxide solution with a mass concentration of 30%; preferably, the amount of the catalyst added is 50 L / h;

[0014] And / or, an oxidant is added during the oxidative desulfurization, wherein the oxidant is hydrogen peroxide with a mass concentration of 27.5%; preferably, the amount of the oxidant added is 10 L / h;

[0015] And / or, the pressure inclined plate tank is made of non-metallic material, preferably FRP glass fiber reinforced plastic;

[0016] And / or, a coagulant and a flocculant are added after the oxidative desulfurization, the coagulant is PAC (polyaluminium chloride), and the flocculant is PAM (polyacrylamide); preferably, the amount of the coagulant added is 20 L / h, and the amount of the flocculant added is 20 L / h.

[0017] According to some embodiments of the present invention, the deep treatment includes stirring clarification treatment, primary filtration, oxidation treatment, secondary filtration and membrane treatment; preferably, the primary filtration is carried out in a corundum filter, and the secondary filtration is carried out in a manganese sand filter.

[0018] The diamond sand filter used for the primary filtration and the manganese sand filter used for the secondary filtration in the present invention are both conventional instruments in the art, and there are no special requirements, and any commonly available instruments on the market can be used.

[0019] According to some embodiments of the present invention, the oxidation treatment includes electrolytic oxidation and Fenton oxidation; preferably, the electrolytic oxidation is performed in an electrolytic oxidation device; further preferably, the positive electrode of the electrolytic oxidation device adopts a sub-titanium oxide ceramic membrane electrode, and the negative electrode adopts a 316L electrode;

[0020] The Fenton oxidation is carried out in a Fenton oxidation device; preferably, the Fenton oxidation device includes a reagent mixing zone, a Fenton reaction zone, a degassing zone, a coagulation reaction zone, a primary sedimentation zone and an inclined tube sedimentation zone.

[0021] The electrolytic oxidation device and Fenton oxidation device used in the oxidation treatment process of the present invention are both conventional devices in the art, and there are no special requirements, and any commonly available devices on the market can be used.

[0022] According to some embodiments of the present invention, the membrane treatment includes DTRO membrane treatment and RO membrane treatment, the DTRO membrane treatment is performed in a DTRO device, and the RO membrane treatment is performed in a RO device;

[0023] Further preferably, the membrane treatment process also includes MVR evaporation treatment, and the MVR evaporation treatment is performed in an MVR evaporation device.

[0024] The DTRO device, RO device and MVR evaporation device used in the membrane treatment process of the present invention are all conventional devices in the art, and there are no special requirements, and any common commercially available devices can be used.

[0025] According to some embodiments of the present invention, the stirring clarification treatment is carried out in a mechanical stirring clarification tank; a clarifier is also added during the stirring clarification treatment, and the clarifier is at least one of a NaOH solution, a Na2CO3 solution, a PAC solution, and a PAM solution; preferably, the mass concentration of the NaOH solution is 30%, the mass concentration of the Na2CO3 solution is 10%, the mass concentration of the PAC solution is 5%, and the mass concentration of the PAM solution is 1%.

[0026] The stirring and clarifying tank used in the present invention is a conventional device in the art, and has no special requirements, and any commonly available one on the market can be used.

[0027] In the present invention, in the pretreatment link of sulfur-containing wastewater, the residual acid separated by the separator and the sulfur-containing wastewater such as the gas field water and the acidic water from the desulfurization area are discharged into the produced water buffer tank in the station, and then hydrochloric acid with a mass concentration of 10% is added to adjust the pH value of the sulfur-containing wastewater to 4.5-5.5, and then enters the nitrogen stripping tower for stripping, and the stripping gas at the top of the tower is sucked by the water ring compressor to maintain the slight positive pressure operation in the tower, and the low-pressure gas (operating pressure of 0.1MPa-0.3MPa) at the outlet of the water ring compressor goes to the acid gas separator tank of the desulfurization unit (the desulfurization unit is irrelevant to the process of the present invention), and finally enters the Claus furnace; the produced water after stripping enters the oxidative desulfurization unit, and is stripped by the stripping gas. After the lifting pump is lifted, hydrogen peroxide and catalyst (alkaline solution) are added into the pressure inclined plate tank for desulfurization, and coagulants and flocculants are added to remove suspended matter in the water. The reaction time of the produced water after stripping in the pressure inclined plate tank is ≥6h, ensuring that the suspended matter concentration of the effluent is ≤30mg / L and the sulfide concentration is ≤10mg / L; the gas field water after oxidation desulfurization is filtered through two stages and the effluent index reaches oil concentration ≤30mg / L, suspended matter concentration ≤15mg / L, and the median particle size ≤3um before entering the pressure two-phase buffer tank. After the residual acid is treated in the initial stage of production, it is loaded and transported to the reinjection station for treatment through a loading pump. In the later stage, the gas field water is transported or exported to the deep treatment unit for further treatment.

[0028] According to the present invention, the operating pressure of the nitrogen stripping tower is 0MPa-0.050MPa; the sulfide concentration at the liquid inlet of the nitrogen stripping tower is ≤3000mg / L, and the sulfide concentration at the liquid outlet is ≤10mg / L.

[0029] According to the present invention, in the above-mentioned two-stage filtration, the first-stage filter is a double-filter material filter (2 units), and the second-stage filter is a corundum filter (2 units); and an override process is set, that is, the incoming water can override the first-stage filter and directly enter the second-stage filter; the diameters of the two-stage filters are both 1.2m, and the filters are set with 3 backwashing modes, including pressure difference backwashing (flushing after the pressure difference reaches 0.07MPa), timed backwashing (flushing once every 12 hours), and manual backwashing (manually starting the flushing process depending on the water output situation).

[0030] In the present invention, when the oxidation desulfurization treatment unit is under maintenance, the gas well is shut down, and the main treatment object of the produced water pretreatment unit of the desulfurization station (the pretreatment link of sulfur-containing wastewater) is the maintenance wastewater. The maintenance wastewater in the maintenance wastewater buffer tank is pressurized by a lifting pump and then transported into a pressure inclined plate tank. During the transportation, hydrogen peroxide and a catalyst (alkali solution) are added into the pressure inclined plate tank for desulfurization, and coagulants and flocculants are added to remove suspended matter in the water. The reaction time of the maintenance wastewater in the pressure inclined plate tank is ≥6h, ensuring that the effluent suspended matter concentration is ≤30mg / L and the sulfide concentration is ≤10mg / L. After the oxidation desulfurization, the maintenance wastewater is filtered through two stages and the effluent index reaches an oil concentration of ≤30mg / L, a suspended matter concentration of ≤15mg / L, and a particle size median of ≤3um, and enters the pressure two-phase buffer tank, and is loaded by a loading pump for external transportation or external transportation to a gas field water deep treatment unit.

[0031] In the present invention, the deep treatment unit of sulfur-containing wastewater mainly performs deep treatment on pre-treated gas field water, acidic water, alkaline wastewater, maintenance wastewater and production wastewater generated by the purification unit. According to the different water qualities to be treated, it is divided into two processes: gas field water process and production wastewater process; among them, the gas field water process mainly treats pre-treated gas field water, maintenance wastewater and alkaline wastewater; the production wastewater process mainly treats initial rainwater, acid-base neutralization water, condensate station sewage, boiler sewage, waste heat boiler sewage, circulating water field sewage, and device flushing. The sulfur-containing sewage after qualified treatment of the above types of wastewater is used as the supplementary water of the public engineering circulating cooling water system, and the two processes share the DTRO device, RO device and MVR evaporation device.

[0032] In the present invention, the deep treatment of sulfur-containing wastewater is carried out by transporting the pretreated maintenance wastewater to the maintenance wastewater receiving tank in the station, lifting it to the gas field water receiving tank through a lifting pump, and at the same time, the pretreated gas field water is transported to the gas field water receiving tank in the station, and the pretreated gas field water and the maintenance wastewater are lifted together to the mechanical stirring clarification tank through a lifting pump, and the alkaline wastewater is transported to the alkaline wastewater receiving tank in the station, and lifted to the mechanical stirring clarification tank through a lifting pump, and then a clarifier is added to the mechanical stirring clarification tank (the clarifier is a sodium carbonate solution with a mass concentration of 10%, a sodium hydroxide solution with a mass concentration of 30%, a PAC solution with a mass concentration of 5%, and a PAM solution with a mass concentration of 1‰; wherein, the addition amount of sodium carbonate is 300L / h, the addition amount of sodium hydroxide is 400L / h, the addition amount of PAC is 45L / h, and the addition amount of PAM is 30L / h, and the mass concentration is 1‰), and Ca is removed. 2+ Mg 2+ Scale-forming ions, effluent water quality Ca 2+ Mg 2+The content of each is ≤15mg / L; the effluent from the mechanical stirring clarification tank is temporarily stored in the filter buffer tank, lifted by the lifting pump to the diamond sand filter for filtration, and then enters the electrolytic oxidation device, where the electrolytic reactor is used to electrolytically oxidize and remove ammonia nitrogen and part of COD in the water. The effluent water quality COD cr ≤800mg / L, ammonia nitrogen ≤10mg / L, then the effluent enters the Fenton oxidation device, and hydrochloric acid with a mass concentration of 10% is added to the inlet pipeline of the Fenton oxidation device to adjust the pH value of the inlet water to between 2 and 3, and then ferrous sulfate solution with a mass concentration of 10% and hydrogen peroxide with a mass concentration of 27.5% are added, and the effluent enters the mixing area of ​​the Fenton oxidation device for reagent mixing. The finished water with complete reagent mixing enters the Fenton reaction area. After reacting for 5 hours, it enters the degassing area and adds 3% ferrous sulfate solution with a mass concentration. 0% sodium hydroxide solution, adjust the pH value of the effluent to 6-8, and generate iron hydroxide precipitation at the same time. After the pH value adjustment is completed, the effluent enters the coagulation reaction zone of the Fenton oxidation device, wherein the flocculant is PAM, the addition amount of PAM is 60L / h, and the injection concentration of the flocculant is 1‰. After the flocculation is completed, the effluent enters the primary sedimentation zone of the Fenton oxidation device, the effluent of the primary sedimentation zone enters the inclined tube sedimentation zone, and the effluent of the inclined tube sedimentation zone enters the buffer water tank of the Fenton oxidation device, and the final effluent water quality COD cr ≤100mg / L, ammonia nitrogen ≤10mg / L, chloride concentration ≤9000mg / L, the effluent from the Fenton oxidation device is filtered through a manganese sand filter and then enters the high-pressure membrane raw water tank;

[0033] At this time, the production wastewater is discharged to the production wastewater receiving tank in the station, and the production wastewater is lifted to another mechanical stirring clarification tank by a lifting pump. After stirring and clarifying treatment, the effluent is temporarily stored in another filter buffer tank, and then lifted to another diamond sand filter by a lifting pump and enters the high-pressure membrane raw water tank. Then the gas field water is mixed with the production wastewater and enters the membrane treatment link together;

[0034] The gas field water and production wastewater in the high-pressure membrane raw water tank are discharged into the DTRO device. The membrane water produced by the DTRO device enters the low-pressure membrane raw water tank, and the concentrated water enters the MVR evaporation device for evaporation. The water produced by the MVR evaporation device enters the low-pressure membrane raw water tank. The output water of the low-pressure membrane raw water tank is lifted by the reverse osmosis booster pump and then enters the reverse osmosis high-pressure pump for pressurization after passing through the security filter. The pressurized water enters the RO device. The output water of the RO device enters the finished water tank and is then transported to the outside by the finished water pump. The concentrated water of the RO device enters the high-pressure membrane raw water tank for circulation again.

[0035] In the prior art, MVR evaporation devices are generally not used to treat concentrated water. Considering that its power consumption is relatively large, the present invention uses the self-produced gas in the device area as the heating medium of the MVR evaporation device, which can save electricity costs, reduce energy consumption and costs; the MVR evaporation device can further concentrate the concentrated water into mother liquor, thereby increasing the water production rate of finished water.

[0036] According to the present invention, the main function of the mechanical stirring clarification tank used is to remove Ca in gas field water, maintenance wastewater, alkaline wastewater and production wastewater. 2+ Mg 2+ The scaling ions are removed by a process combining chemical softening and suspended sludge circulation purification, wherein the dosage of the added chemical is adjusted according to the water quality of the incoming water; the liquid level of the mechanical stirring clarification tank is set at 6.6m as the alarm upper limit, the lifting pump is interlocked to stop the pump, and it has its own PLC control cabinet, which can realize remote and local control, and the stirring device adopts frequency conversion control and can adjust the speed; this equipment is conventional equipment in this field, there are no special requirements, and ordinary commercially available equipment can be used.

[0037] According to the present invention, the diamond sand filter used is provided with 2 filter tanks, with a diameter of 3m and a water flow rate of 65m 3 / h, the diamond abrasive filter has three backwashing modes, including differential pressure backwashing (flushing after reaching 0.07MPa), timed backwashing (flushing every 12h), and manual backwashing (manually starting the flushing process depending on the water outlet). The backwashing pump is interlocked with the liquid level of the low-pressure membrane raw water tank. When the liquid level is low, the backwashing pump is interlocked to shut down the backwashing pump. It can be operated locally and remotely, and can be uploaded to the central control room. This equipment is conventional in this field and has no special requirements. It can be purchased on the market.

[0038] According to the present invention, the electrolytic oxidation device used has a designed processing capacity of 30m 3 / h. The main process is that the water from the diamond sand filter enters the electrolytic reactor of the electrolytic oxidation device. Through electrolysis, hypochlorite, hydroxyl radicals and other strong oxidizing substances are produced in the water to remove ammonia nitrogen and part of COD in the water. The COD of the effluent water quality cr ≤800mg / L, ammonia nitrogen ≤10mg / L; the electrolytic oxidation device will produce a small amount of chlorine during the electrolysis process, and this part of the gas will enter the tail gas treatment system for treatment; the electrolytic reactor is divided into two stages, each stage of the electrolytic reactor contains 10 electrolyzers, with a designed treatment capacity of 30m 3 / h, electrodes are arranged inside the electrolytic reactor, the positive electrode adopts a sub-titanium oxide ceramic membrane electrode, and the negative electrode adopts a titanium metal electrode; this equipment is conventional equipment in this field, there is no special requirement, and ordinary commercially available equipment can be used.

[0039] According to the present invention, the main function of the Fenton oxidation device is to further remove organic pollutants such as COD in the water produced by the electrolytic oxidation device; the designed processing capacity of the Fenton oxidation device is 30m 3 / h, divided into two rows, the processing capacity of each row is 15m 3 / h, the Fenton oxidation device includes reagent mixing zone, Fenton reaction zone, degassing zone, coagulation reaction zone, primary sedimentation zone and inclined tube sedimentation zone, among which the reagent mixing zone has the size of 2m×3m×5m, the Fenton reaction zone has the size of 11m×3m×5m, the degassing zone has the size of 2m×3m×5m, the coagulation reaction zone has the size of 2m×3m×5m, the primary sedimentation zone has the size of 3m×3m×5m, the inclined tube sedimentation zone has the size of 4m×3m×5m, and the buffer water tank has the size of 2m×3m×5m. The Fenton reaction zone adopts a fully mixed plug flow design. The mixing of water and reagents in the reaction zone is achieved by air aeration. The main function of the coagulation reaction zone is to remove residual hydrogen peroxide and flocculation reaction. An online pH monitor and redox potential monitor are installed in the Fenton oxidation device skid, which can monitor the pH value and redox characteristics of the entire skid in real time online and on-site. The Fenton oxidation buffer water tank is equipped with high and low liquid level alarms and extremely low liquid level interlocks to stop the manganese sand filter lift pump; the manganese sand filter tank is conventional equipment in this field, without special requirements, and any ordinary commercially available one can be used.

[0040] According to the present invention, the manganese sand filter tank has a diameter of 2m and is provided with two tanks. The manganese sand filter tank is conventional equipment in the art and has no special requirements and can be any common commercially available equipment.

[0041] According to the present invention, the main function of the DTRO device is to reduce the volume of wastewater, desalinate, remove part of the COD, etc. The device is designed to process 45m 3 / h, divided into 3 sets, single row processing capacity is 15m 3 / h, the system water production rate is ≥55%; the DTRO device is a conventional device in the field, there is no special requirement, and any common commercially available device can be used.

[0042] According to the present invention, the RO device is designed to process water at a rate of 100 m 3 / h, the raw water is the water produced by the DTRO device, the water produced by the MVR evaporation device and the filtered production wastewater, and the system water production rate is ≥85%; the RO device adopts a combination of one stage and two stages; the pressurized water first enters the first stage reverse osmosis membrane system, the concentrated water produced by the first stage reverse osmosis membrane enters the second stage reverse osmosis membrane for further treatment, and the concentrated water produced by the second stage reverse osmosis membrane returns to the high-pressure membrane raw water tank. The water produced by the first and second stage reverse osmosis membranes is collected together and enters the rear-end finished water delivery system; in addition, the RO device is also equipped with a dosing device, among which the scale inhibitor dosing device is mainly used to prevent the membrane surface of the reverse osmosis membrane from scaling during operation, the reducing agent dosing device is mainly used to add sodium bisulfite, and the pH value regulator dosing device is mainly used to adjust the pH of the effluent of the reverse osmosis system. The RO device effluent is equipped with online conductivity and pH online instruments to monitor the effluent in real time; the RO device is a conventional device in this field, there are no special requirements, and ordinary commercial products can be used.

[0043] According to the present invention, the main function of the MVR evaporation device is to remove the heavy components COD and TDS in the water, and the water production rate is ≥90%; the MVR evaporation device adopts a treatment process combining vertical tube falling film evaporation and forced circulation evaporation; wherein, the vertical tube falling film evaporation process is used to concentrate the TDS of gas field water and production wastewater to 20000mg / L, and then enter the forced circulation evaporation, and the forced circulation evaporator further evaporates and concentrates the gas field water and production wastewater, and the TDS is 430000mg / L (solid content 15%). The MVR evaporation device will produce COD mother liquor in the forced circulation process section, and the mother liquor enters the mother liquor tank and is handed over to a qualified third party for treatment.

[0044] According to the present invention, when the MVR evaporation device is started, steam is required to be started, and the steam volume is 8 t / h (150°C, 0.35 MPa). After the startup is completed, the steam required by the evaporation device is obtained by pressurizing and heating the secondary steam generated by the evaporation device through a centrifugal compressor. During the operation, the steam volume that needs to be continuously supplemented is 1 to 2 t / h. The non-condensable gas generated during the operation of the MVR evaporation device is extracted through a water ring vacuum pump. During the operation of the entire MVR evaporation device, the pressure in the evaporation chamber is -0.04 MPa, and the secondary steam temperature is 85°C.

[0045] According to the present invention, the MVR evaporation device is a conventional device in the art. What is different from the prior art is that it uses steam generated by a boiler for heating. Steam is a self-produced and recycled medium in the device area, and no additional electricity costs are generated, which has an energy-saving effect.

[0046] In the present invention, the gas field water receiving tank, maintenance waste water receiving tank, alkaline waste water receiving tank and production waste water receiving tank are mainly set according to the amount of gas field water, maintenance waste water, alkaline waste water and production waste water, and receiving tanks of different volumes are used to receive water from different sources.

[0047] The second aspect of the present invention provides an application of a sulfur-containing wastewater treatment process in the treatment of gas field water and / or wastewater generated by a purification unit; preferably, the wastewater is at least one of residual acid, acidic water, alkaline wastewater, maintenance wastewater, and production wastewater.

[0048] In the present invention, the initial residual acid waste liquid is treated separately from general gas field water and maintenance waste water in the pretreatment stage. The initial residual acid waste liquid is reinjected after treatment, and the general gas field water and maintenance waste water are deeply treated after pretreatment.

[0049] Beneficial effects:

[0050] The present invention firstly utilizes a nitrogen micro-positive pressure stripping process for sulfur-containing wastewater. Compared with a conventional positive pressure stripping process, the process can maximize the stripping effect under the condition of reducing the amount of stripping gas used. The sulfide in the outlet sulfur-containing wastewater can be reduced to below 10 mg / L, and nitrogen pressurization recovery is achieved, reducing carbon dioxide emissions. The process has the characteristics of being able to achieve a significant reduction in hydrogen sulfide in the sulfur-containing wastewater and ensuring efficient stripping gas recovery.

[0051] Secondly, the pretreatment of sulfur-containing wastewater adopts the mode of oxidative desulfurization, and for the first time uses non-metallic pressure vessels as containers for oxidation reactions. Compared with the traditional oxidative desulfurization process, which mainly uses metal containers and underground excavated sulfur-containing wastewater pools, it reduces the cost of irregular replacement of anti-corrosion coatings while ensuring the desulfurization effect and corrosion resistance, and can ensure a certain pressure resistance level while meeting the desulfurization effect;

[0052] The sulfur-containing wastewater treatment process of the present invention integrates all sulfur-containing wastewater treatment functions involved in the collection, transportation and purification links of sulfur-containing gas fields, can select reasonable treatment processes for different water qualities, and incorporate different waters into the treatment at different process stages. Ultimately, the effluent water quality of all sulfur-containing wastewater reaches the reuse water index, truly realizing resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a pretreatment process for sulfur-containing wastewater such as gas field water, residual acid, and acidic water;

[0054] Figure 2 Overhaul wastewater pretreatment process flowsheet for purification unit;

[0055] Figure 3 It is a deep treatment process for pretreated gas field water, maintenance wastewater, alkaline wastewater and production wastewater. DETAILED DESCRIPTION

[0056] The present invention will be further described below in conjunction with the embodiments, but the present invention is not limited by these embodiments.

[0057] In the embodiment of the present invention, the operating pressure of the produced water buffer tank is 0.1MPa-0.3MPa, and the temperature is 20°C-40°C.

[0058] In the embodiment of the present invention, the inner diameter of the nitrogen stripping tower is 800 mm, the height is 12000 mm, and the design pressure is 1.0 MPa.

[0059] In the embodiment of the present invention, the inlet pressure of the water ring compressor is 0MPa-0.05MPa, the outlet pressure is 0.25MPa, and the displacement is 20m 3 / h~150m 3 / h.

[0060] The design pressure of the pressure inclined plate tank in the embodiment of the present invention is 0.6MPa, the operating pressure is 0.3MPa, the design temperature is 60℃, the operating temperature is 30℃, and the volume is 60m 3 .

[0061] Unless otherwise specified, the acid gas separator tank, Claus furnace, lift pump, and two-phase buffer tank described in the embodiments of the present invention are all common commercially available products.

[0062] The polyaluminium chloride and polyacrylamide used in the embodiments of the present invention are both common commercially available products, and there are no other special requirements.

[0063] Example 1

[0064] This embodiment provides a process for treating sulfur-containing wastewater, comprising the following steps:

[0065] (I) Pretreatment of sulfur-containing wastewater: The gas field water is uniformly discharged into the produced water buffer tank in the station, and then hydrochloric acid with a mass concentration of 10% is added to adjust the pH value of the gas field water to 5.0. The gas field water (sulfide concentration is 1200 mg / L) enters the stripping tower and is stripped by nitrogen. The stripping gas at the top of the tower is sucked by the water ring compressor to maintain a slight positive pressure in the tower. The inlet flow rate of the gas field water is 10m 3 / h, the amount of nitrogen introduced into the stripping tower is 9 times the amount of gas field water introduced (i.e. the gas-liquid ratio is 9:1), and the operating pressure in the stripping tower is 0.008MPa;

[0066] The low-pressure gas at the outlet of the water ring compressor goes to the acid gas separator of the desulfurization unit and finally enters the Claus furnace. The gas field water (sulfide concentration is 8 mg / L) after stripping is lifted by a lifting pump, and then a sodium hydroxide solution with a mass concentration of 30% is added, and then a hydrogen peroxide with a mass concentration of 27.5% is added and then enters the pressure inclined plate tank for oxidative desulfurization. After oxidative desulfurization, PAC and PAM are added to remove suspended matter in the water. The measured suspended matter concentration in the water is 20 mg / L, and the sulfide concentration is 6 mg / L; wherein, the amount of sodium hydroxide solution added is 50 L / h, the amount of PAC added is 20 L / h, the filling concentration is 5wt% (that is, after adding PAC, the concentration of PAC in the gas field water is 5wt%), the amount of PAM added is 20 L / h, the filling concentration is 1% (that is, after adding PAM, the concentration of PAM in the gas field water is 1wt%), and the time of oxidative desulfurization is 7h;

[0067] After oxidation desulfurization and removal of suspended solids, the gas field water is filtered through two stages and the effluent index reaches 25mg / L oil content, 10mg / L suspended solids concentration, and 2um median particle size. The water enters the two-phase buffer tank and is transported or exported to the deep treatment unit for further treatment. The reference standard for the effluent index is "Water Quality Index and Analysis Method for Water Injection in Clastic Reservoirs" SY / T-5329-2012.

[0068] (II) Advanced treatment of sulfur-containing wastewater: The pre-treated gas field water is transported to the gas field water receiving tank in the station. The chemical oxygen demand (COD) of the pre-treated gas field water is cr The pretreated gas field water is lifted to a mechanical stirring clarification tank by a lifting pump, and a clarifier is added (the clarifier is a sodium carbonate solution with a mass concentration of 10%, a sodium hydroxide solution with a mass concentration of 30%, a PAC solution with a mass concentration of 5%, and a PAM solution with a mass concentration of 1‰; among which, the addition amount of sodium carbonate is 300L / h, the addition amount of sodium hydroxide is 400L / h, the addition amount of PAC is 45L / h, and the addition amount of PAM is 30L / h, and the mass concentration is 1‰) to remove Ca 2+ Mg 2+ Scale-forming ions, effluent water quality Ca 2+ Mg 2+ The content is ≤15mg / L; the effluent from the mechanical stirring clarification tank is temporarily stored in the filter buffer tank, lifted by the lifting pump to the diamond sand filter for filtration, and then enters the electrolytic oxidation device. The electrolytic reactor is used to electrolytically oxidize and remove ammonia nitrogen and part of COD in the water. The chemical oxygen demand (COD) of the effluent water quality is cr The pH value of the inlet water is adjusted to between 2.5 and 500 mg / L, and the ammonia nitrogen is 7 mg / L. The effluent then enters the Fenton oxidation device. A 10% hydrochloric acid is added to the inlet pipeline of the Fenton oxidation device to adjust the pH value of the inlet water to between 2.5. Subsequently, a 10% ferrous sulfate solution and a 27.5% hydrogen peroxide solution are added (the amount of ferrous sulfate solution added is 320 L / h, and the amount of hydrogen peroxide added is 200 L / h). The effluent enters the mixing area of ​​the Fenton oxidation device for reagent mixing. The finished product water after the reagent mixing is completely mixed enters the Fenton reaction area. After reacting for 5 hours, it enters the Fenton reaction area. Enter the degassing zone, add 30% sodium hydroxide solution, adjust the pH value of the effluent to 7.0, and generate iron hydroxide precipitation. After the pH value is adjusted, the effluent enters the coagulation reaction zone of the Fenton oxidation device, where the flocculant is PAM, the amount of PAM added is 60L / h, and the concentration of the flocculant is 1‰. After flocculation, the effluent enters the primary sedimentation zone of the Fenton oxidation device, the effluent of the primary sedimentation zone enters the inclined tube sedimentation zone, and the effluent of the inclined tube sedimentation zone enters the buffer water tank of the Fenton oxidation device. The final effluent water quality chemical oxygen demand COD cr The concentration of nitrogen is 80mg / L, ammonia nitrogen is 7mg / L, and the concentration of chloride ion is 7000mg / L. The effluent from the Fenton oxidation device is filtered through a manganese sand filter and then enters the high-pressure membrane raw water tank.

[0069] Then the gas field water in the high-pressure membrane raw water tank is discharged into the DTRO device, and the membrane water of the DTRO device enters the low-pressure membrane raw water tank. The concentrated water is discharged at a rate of 1.5m 3 / h flow rate enters the MVR evaporation device for evaporation at a temperature of 98°C, of ​​which the steam volume is 1.5t / h. The water produced by the MVR evaporation device enters the low-pressure membrane raw water tank, and the water out of the low-pressure membrane raw water tank enters the RO device. The water out of the RO device enters the finished water tank. The water quality of the water out of the RO device is chemical oxygen demand COD cr The concentration of nitrogen is 20mg / L, ammonia nitrogen is 4.5mg / L, chloride concentration is 30mg / L, and sulfate concentration is 486mg / L. After that, it is transported out through the finished water pump, and the concentrated water of the RO device enters the high-pressure membrane raw water tank for further circulation.

[0070] Example 2-29

[0071] The treatment process of sulfur-containing wastewater provided in Example 2-29 is the same as that in Example 1, except that different gas-liquid ratios, sulfide concentrations of the sulfur-containing wastewater, and pH values ​​are selected. The specific process conditions are shown in Table 1 below; before and after oxidation and desulfurization of the sulfur-containing wastewater, the sulfide concentration, suspended matter concentration, median particle size and sulfide removal rate of the sulfur-containing wastewater provided in Example 2-29 are specifically shown in Table 2 below.

[0072] Table 1

[0073]

[0074]

[0075] Table 2

[0076]

[0077] The sulfide removal rate in Table 2 is the removal rate of sulfide in sulfur-containing wastewater during the oxidation desulfurization stage.

[0078] Examples 30-56

[0079] The treatment process for sulfur-containing wastewater provided in Examples 30-56 is the same as that in Example 1, except that the operating pressure in the stripping tower is 0.045 MPa, and different gas-liquid ratios, sulfide concentrations of the sulfur-containing wastewater, and pH values ​​are selected. The specific process conditions are shown in Table 3 below; before and after oxidation and desulfurization of the sulfur-containing wastewater, the sulfide concentration, suspended matter concentration, median particle size and sulfide removal rate of the sulfur-containing wastewater provided in Examples 30-56 are specifically shown in Table 4 below.

[0080] Table 3

[0081]

[0082] Table 4

[0083]

[0084]

[0085] The sulfide removal rate in Table 4 is the removal rate of sulfide in sulfur-containing wastewater during the oxidation desulfurization stage.

[0086] Examples 57-83

[0087] The treatment process for sulfur-containing wastewater provided in Examples 57-83 is the same as that in Example 1, except that the operating pressure in the stripping tower is 0.11 MPa, and different gas-liquid ratios, sulfide concentrations of the sulfur-containing wastewater, and pH values ​​are selected. The specific process conditions are shown in Table 5 below; before and after oxidation and desulfurization of the sulfur-containing wastewater, the sulfide concentration, suspended matter concentration, median particle size and sulfide removal rate of the sulfur-containing wastewater provided in Examples 57-83 are specifically shown in Table 6 below.

[0088] Table 5

[0089]

[0090]

[0091] Table 6

[0092]

[0093] The sulfide removal rate in Table 6 is the removal rate of sulfide in sulfur-containing wastewater during the oxidation desulfurization stage.

[0094] Comparative Examples 1-10

[0095] The treatment process of sulfur-containing wastewater provided in Comparative Examples 1-10 is the same as that in Example 1, except that different operating pressures in the stripping tower, gas-liquid ratios, sulfide concentrations of the sulfur-containing wastewater, and pH values ​​are selected. The specific process conditions are shown in Table 7 below; before and after pretreatment of the sulfur-containing wastewater, the sulfide concentration, suspended matter concentration, median particle size, and sulfide removal rate of the sulfur-containing wastewater provided in Comparative Examples 1-10 are specifically shown in Table 8 below.

[0096] Table 7

[0097]

[0098] Table 8

[0099]

[0100] Through the comparison of the above-mentioned micro-positive pressure stripping and positive pressure stripping operation tests, it can be seen that the removal effect of sulfide in sulfur-containing wastewater by the operating pressure in the stripping tower increases with the decrease of the working pressure in the stripping tower; therefore, in order to achieve an effluent sulfide concentration of ≤10mg / L, the operating pressure in the micro-positive pressure stripping tower is controlled at 0MPa~0.05MPa, and the gas-liquid ratio is controlled at (7:1)~(8;1).

[0101] For the oxidation and desulfurization stage of sulfur-containing wastewater, most processes use metal tanks and build sulfur-containing wastewater pools as the place for oxidation reaction and coagulation and sedimentation after adding drugs. However, during use, it is more troublesome to clean the sludge at the bottom of the sludge pool. The present invention uses non-metallic pressure vessels as the place for integrated oxidation reaction and coagulation and sedimentation, which simplifies the process flow and ensures better anti-corrosion effect. It is also the first time that non-metallic pressure vessels are used in the treatment of sulfur-containing wastewater in sulfur-containing gas fields.

[0102] Examples 84-88

[0103] The treatment process of sulfur-containing wastewater provided in Examples 84-88 is the same as that in Example 1, except that the chemical oxygen demand (COD) of the gas field water after different pretreatment is cr concentration, MVR evaporation temperature, steam volume, specific process conditions are shown in Table 9 below; before and after deep treatment of pretreated gas field water, the inlet COD of the DTRO device of the pretreated gas field water provided in Examples 1, 84-88 cr Concentration, RO device effluent COD cr Concentration and COD cr The removal rates are shown in Table 10 below.

[0104] Table 9

[0105]

[0106] Table 10

[0107]

[0108] The effluent quality of the final deep treatment stage meets the water quality requirements for circulating cooling water system makeup water in the "Assessment Indicators for Water Saving and Emission Reduction in Refining and Chemical Enterprises and Control Indicators for Recycled Water Quality" (Q / SH0104-2007).

[0109] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A sulfur-containing wastewater treatment process, including pretreatment and deep treatment, characterized in that: The pretreatment includes steam stripping and oxidative desulfurization; the pressure of the steam stripping is 0MPa to 0.05MPa; the sulfide concentration in the pretreated sulfur-containing wastewater is ≤10mg / L; The oxidative desulfurization is carried out in a pressure inclined plate tank.

2. The sulfur-containing wastewater treatment process according to claim 1, characterized in that: The stripping is carried out in a nitrogen stripping tower, and the amount of nitrogen introduced into the nitrogen stripping tower is 8 to 10 times the amount of the sulfur-containing wastewater introduced; And / or, a pH regulator is added before the stripping, wherein the pH regulator is hydrochloric acid with a mass concentration of 10%; preferably, the pH regulator is added to adjust the pH to 4.5-5.5, preferably 5.0; And / or, a catalyst is added after the stripping, wherein the catalyst is a sodium hydroxide solution with a mass concentration of 30%; preferably, the amount of the catalyst added is 50 L / h; And / or, an oxidant is added during the oxidative desulfurization, wherein the oxidant is hydrogen peroxide with a mass concentration of 27.5%; preferably, the amount of the oxidant added is 10 L / h; And / or, the pressure inclined plate tank is made of non-metallic material; the non-metallic material is preferably glass fiber reinforced plastic; And / or, a coagulant and a flocculant are added after the oxidative desulfurization, the coagulant is preferably polyaluminium chloride, and the flocculant is preferably polyacrylamide; preferably, the amount of the coagulant added is 20 L / h, and the amount of the flocculant added is 20 L / h.

3. The sulfur-containing wastewater treatment process according to claim 1 or 2, characterized in that: The deep treatment includes stirring clarification treatment, primary filtration, oxidation treatment, secondary filtration and membrane treatment; preferably, the primary filtration is carried out in a corundum filter, and the secondary filtration is carried out in a manganese sand filter.

4. The sulfur-containing wastewater treatment process according to any one of claims 1 to 3, characterized in that: The oxidation treatment includes electrolytic oxidation and Fenton oxidation; preferably, the electrolytic oxidation is carried out in an electrolytic oxidation device; And / or, the Fenton oxidation treatment is carried out in a Fenton oxidation device; preferably, the Fenton oxidation device includes a reagent mixing zone, a Fenton reaction zone, a degassing zone, a coagulation reaction zone, a primary sedimentation zone and an inclined tube sedimentation zone.

5. The sulfur-containing wastewater treatment process according to any one of claims 1 to 4, characterized in that: The membrane treatment includes DTRO membrane treatment and RO membrane treatment; preferably, the DTRO membrane treatment is carried out in a DTRO device, and the RO membrane treatment is carried out in a RO device; Further preferably, the membrane treatment process also includes MVR evaporation treatment, and the MVR evaporation treatment is performed in an MVR evaporation device.

6. The sulfur-containing wastewater treatment process according to any one of claims 1 to 5, characterized in that: The stirring clarification treatment is carried out in a mechanical stirring clarification tank; preferably, a clarifier is also added during the stirring clarification treatment; further preferably, the clarifier is at least one of NaOH solution, Na2CO3 solution, PAC solution, and PAM solution; even further preferably, the mass concentration of the NaOH solution is 30%, the mass concentration of the Na2CO3 solution is 10%, the mass concentration of the PAC solution is 5%, and the mass concentration of the PAM solution is 1%.

7. An application of the sulfur-containing wastewater treatment process according to any one of claims 1 to 6 in the treatment of gas field water and / or wastewater generated by a purification unit; preferably, the wastewater is at least one of residual acid, acidic water, alkaline wastewater, maintenance wastewater, and production wastewater.

Images