Oil and gas field water treatment system

Abstract

The invention discloses an oil and gas field water treatment system which comprises a pre-sedimentation treatment system, and the pre-sedimentation treatment system at least comprises a dosing unit and a settling tank unit; the filtering system is communicated with the pre-sedimentation treatment system, wastewater treated by the pre-sedimentation treatment system enters the filtering system, and the filtering system at least comprises a plurality of filtering modules; the security filter system is communicated with the filtering system; the preheating system adopts solar energy to supply energy, and the preheating system preheats the wastewater; the film evaporation system is connected with the preheating system and is used for concentrating the wastewater. Through a synergistic process of pre-sedimentation, high-precision filtration, security filtration, solar preheating and thin film evaporation, high-efficiency treatment and resource utilization of high-salinity wastewater are realized, the total recycling rate is 70-75%, the comprehensive recovery rate can reach 90% or above, meanwhile, strong brine is further desalted and concentrated, salt in water is crystallized into single crystal salt, and the single crystal salt is recycled. And recycling of salt resources is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and particularly relates to an oil and gas field water treatment system. Background Art

[0002] With the continuous development of the petroleum industry, the treatment of high-salt oil and gas field wastewater has become a major challenge faced by the industry. Such wastewater usually has characteristics such as high salinity, high hardness, high COD and TDS, and is difficult to degrade. Among them, the high chloride ion concentration leads to strong corrosiveness, contains a variety of chemical additives, and most of the organic matters are in cyclic forms, with stable structures and poor biodegradability. At the same time, Ca2 + , Mg2 + form hydrates in the form of ion beams or ion clusters, increasing the difficulty of hardness removal. The high suspended solids and stable colloidal state make it difficult to precipitate, resulting in high equipment risks and difficult hazardous waste treatment during the wastewater treatment process. Under the situation of increasingly strict environmental protection requirements, realizing the resource utilization and harmless treatment of high-salinity water, and further desalting and concentrating the brine to recover salt resources is an urgent need for related near-zero discharge treatment processes.

[0003] At present, the existing wastewater treatment technologies have many deficiencies when dealing with high-salt oil and gas field wastewater. Traditional treatment methods are difficult to effectively cope with the complex characteristics of wastewater such as high salinity, high hardness, and high COD, resulting in poor treatment effects and unable to meet the increasingly strict environmental protection standards. Summary of the Invention

[0004] The purpose of the present invention is to propose an oil and gas field water treatment system to solve the problems in the prior art.

[0005] To this end, the present invention provides an oil and gas field water treatment system, including:

[0006] A pre-sedimentation treatment system, the pre-sedimentation treatment system at least includes a chemical dosing unit and a sedimentation tank unit for removing large particle sludge from the wastewater;

[0007] A filtration system, the filtration system is connected to the pre-sedimentation treatment system, and the wastewater treated by the pre-sedimentation treatment system enters the filtration system. The filtration system at least includes a plurality of filtration modules with a precision of 1-5 μm for removing small particle impurities from the wastewater;

[0008] A security filter system, the security filter system is connected to the filtration system;

[0009] A preheating system, the preheating system uses solar energy for power supply and preheats the wastewater;

[0010] A thin-film evaporation system, which is connected to the preheating system and is used for concentrating wastewater.

[0011] As a further description of the above technical solution, the pre-sedimentation treatment system includes the chemical dosing unit, which is arranged at one end of the sedimentation tank unit. A stirring unit is arranged at one end of the sedimentation tank, and inclined tube sedimentation fillers are arranged in the middle of the sedimentation tank unit.

[0012] As a further description of the above technical solution, the chemical dosing unit includes a metering pump, which is connected to a chemical storage tank. The chemical dosing unit is used to add 0.01% PAC and 0.002% PAM to the sedimentation tank unit.

[0013] As a further description of the above technical solution, the filter system includes multiple filter module groups, which are connected to a clear liquid storage tank through a water outlet pipeline;

[0014] A backwashing pipeline is also connected between the clear liquid storage tank and the filter module group, and the clear liquid storage tank can backwash the above filter module group;

[0015] The filter module group is connected to a valve pump group, the clear liquid storage tank is connected to a sterilizer, and a water outlet is arranged on one side of the sterilizer.

[0016] As a further description of the above technical solution, the security filter system includes multiple security filter groups, which are connected to a supply pump and a scale inhibitor dosing device.

[0017] As a further description of the above technical solution, the preheating system includes a solar heating module or an electric auxiliary heating module.

[0018] As a further description of the above technical solution, the thin-film evaporation system includes an evaporation equipment main body, which is connected to a vacuum pump, a multistage centrifugal pump, and a clear liquid buffer tank.

[0019] As a further description of the above technical solution, the evaporation equipment main body includes multiple evaporation towers and multiple absorption towers.

[0020] As a further description of the above technical solution, it further includes a fresh water tank, which is communicated with the thin-film evaporation system and is used for collecting the clear liquid discharged by the thin-film evaporation system.

[0021] Beneficial effects:

[0022] 1. The present invention provides an oil and gas field water treatment system. Through the collaborative processes of pre-sedimentation, high-precision filtration, security filtration, solar preheating, and thin-film evaporation, the efficient treatment and resource utilization of high-salt wastewater are achieved. The overall reuse rate is 70 - 75%, and the comprehensive recovery rate can reach over 90%. At the same time, the concentrated brine is further desalted and concentrated to crystallize a single crystal salt from the water, realizing the recovery and utilization of salt resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is the process flow diagram of the oil and gas field water treatment system provided by the present invention.

[0025] Figure 2 It is the process equipment flow diagram of the oil and gas field water treatment system provided by the present invention.

[0026] In the figure: 100, pre-sedimentation treatment system; 200, filtration system; 300, security filter system; 400, preheating system; 500, thin-film evaporation system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The content of the present invention can be more easily understood by referring to the following detailed description of the preferred implementation methods of the present invention and the included embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. When there is a contradiction, the definition in this specification shall prevail.

[0028] Such as Figure 1-2As shown in the figure, an oil and gas field water treatment system includes a pre-sedimentation treatment system 100. The pre-sedimentation treatment system 100 at least includes a chemical dosing unit and a sedimentation tank unit. Specifically, the chemical dosing unit is arranged at at least one end of the sedimentation tank unit. The chemical dosing unit is specifically a chemical dosing device, which stores at least two chemicals, PAC (polyaluminium chloride) and PAM (polyacrylamide). After the chemicals are stirred, they are added to the sedimentation tank unit through a metering pump. By adding 0.01% PAC as a flocculant, the colloids and suspended solids in the water are destabilized and aggregated mainly through the compression of the double electric layer and the adsorption bridging effect, forming fine flocs. By adding 0.002% PAM as a coagulant aid, through the adsorption sweeping and net trapping effects of the polymer chains, the small flocs are further aggregated into large and dense flocs, accelerating the sedimentation speed. The synergistic effect of the two can significantly improve the solid-liquid separation efficiency, reduce the turbidity and suspended solid content of the effluent, and improve the sludge dewatering performance at the same time. It can effectively remove large particle sludge in the sedimentation tank unit. In some embodiments, the chemical dosing unit, i.e., the chemical dosing device, includes a 2t chemical storage tank, a mechanical diaphragm metering pump with a flow rate of 30L / h, a pneumatic motor stirring device, and inlet and outlet pipelines (not shown in the figure).

[0029] Optionally, inclined tube sedimentation fillers can be arranged in the sedimentation tank unit. They are installed in the middle of the sedimentation tank unit and can quickly sediment the reacted flocs to the bottom cone of the sedimentation tank unit. A sludge discharge pipe is arranged at the bottom of the bottom cone, and a pneumatic sewage discharge valve is arranged on the sludge discharge pipe to discharge the sludge. Optionally, about 12m 3 of inclined tube fillers are arranged in the sedimentation tank unit. The material of the inclined tube fillers is polypropylene, and the thickness is 0.8mm. The inclined tube fillers are spliced and installed at the bottom of the sedimentation tank unit.

[0030] Optionally, a liquid level transmitter is arranged in the sedimentation tank unit, which can effectively solve the problem of water level overflow in the sedimentation tank unit. In some embodiments, the shutdown height limit of the liquid level transmitter can be set to 0 - 800mm.

[0031] The oil and gas field water treatment system further includes a filtration system 200. The filtration system 200 is connected to the pre-sedimentation treatment system 100. The wastewater treated by the pre-sedimentation treatment system 100 enters the filtration system 200. The filtration system 200 includes at least a plurality of filtration modules with a precision of 1-5 μm, which are used to remove small particle impurities in the wastewater. Specifically, the filtration system 200 is a CXM filtration system 200, which includes at least one CXM filtration module group, and also includes structures such as an automatic online cleaning device, a pump valve system, and a PLC automatic control system. The wastewater with small particle suspended solids treated by the pre-sedimentation treatment system 100 is injected into the CXM filtration system 200 by a centrifugal pump. The precision of the CXM filtration equipment is 1-5 μm, and various insoluble impurities in the water body will be completely intercepted. The turbidity of the water discharged from the filtration system 200 is <1 NTU, and the purified clear liquid flows into the main pipeline clear liquid tank. At the same time, every about 0.3-0.5 h, the filtration system 200 automatically performs backwashing and online automatic cleaning with a small amount of clear liquid (about 1%-3%), and returns the backwashing cleaning water with a higher impurity concentration to the sedimentation tank to be discharged to the plant sludge tank for combined treatment.

[0032] Optionally, the filtration system 200 at least includes a filter module group, which filters and removes small particle insoluble substances in the pretreated cooling water to ensure the water quality of the discharged water, and can fully automatically perform functions such as exhaust, filtration, cleaning, backwashing, and slag discharge. In some embodiments, every six groups of CXM filter module groups form a treatment line, and a total of two treatment lines are set. The treatment capacity of a single treatment line can reach 22.5 m 3 / h. In some embodiments, the size of each filter module group is about φ355*1500, the shell is made of stainless steel material, and an integral high-strength filter element tank plate and a polypropylene fiber filter element are adopted, with a precision of 2-5 μm.

[0033] Optionally, the filter module group is connected to the clear liquid storage tank through an outlet pipeline. The clear liquid storage tank is used to buffer part of the clear liquid to perform backwashing on the filter module group. In some embodiments, the clear liquid storage tank adopts a 10t-class PE water storage tank with a diameter of about 1.5 m and a height of about 1.8 m.

[0034] A backwashing pipeline is also connected between the clear liquid storage tank and the filter module group. The clear liquid storage tank can perform backwashing on the above-mentioned filter module group. A backwash pump is connected in the backwashing pipeline, which is used to provide energy for the backwashing clear liquid;

[0035] The filter module group is connected to the valve pump group, the clear liquid storage tank is connected to the sterilizer, and a water outlet is arranged on one side of the sterilizer.

[0036] The oil and gas field water treatment system also includes a security filter system 300, which is connected to the filtration system 200. Specifically, it is a pre - security filtration device, including a liquid supply clean water tank, a security filter group, a security filter liquid supply pump, and a scale inhibitor dosing device. The liquid supply clean water tank is used to provide the influent water for in - depth security filtration, and it can share a clear liquid storage tank with the CXM filtration system 200. The security filter group conducts security filtration before the membrane distillation to avoid accidental insoluble pollution of the water quality. In some embodiments, there are two sets of security filter groups, and each set includes five PPH filtration modules and 90 linear wound filter elements. The liquid supply pump of the security filter injects the clear water in the liquid supply clean water tank into the security filter. In some embodiments, a horizontal centrifugal pump with a power of 4 kW is used. The scale inhibitor dosing device stores the prepared reverse osmosis scale inhibitor, stirs the agent, and quantitatively adds it through a metering pump. The scale inhibitor dosing device includes a 1t - level agent storage tank, a 30L / h mechanical diaphragm metering pump, and a pneumatic motor stirring device.

[0037] Since the oil and gas field wastewater contains relatively high levels of chloride ions and calcium - magnesium ions, desalination treatment is required to meet the discharge standards. And due to the extremely high content of oilfield wastewater, an evaporation process needs to be used for further in - depth treatment. In related technologies, a triple - effect evaporation or MVR evaporation system is generally adopted, but it has the defects of high operating costs and large initial investments. In the present invention, a three - in - one evaporation system is adopted, which specifically includes a pre - heating system 400 and a thin - film evaporation system 500. The pre - heating system 400 is an evaporation heating system, which uses solar heating or electric auxiliary heating. By preliminarily heating the material to make it close to the evaporation temperature, the energy consumption in the subsequent evaporation process is reduced and the treatment efficiency is improved. In some other achievable embodiments, air - source heat pumps can also be used for heating.

[0038] Optionally, the thin - film evaporation equipment includes a thin - film evaporation equipment main body, a vacuum pump, a multi - stage centrifugal pump, a valve group, and an automatic control system. The thin - film evaporation equipment main body includes ten PPH plastic plus fiberglass evaporation towers and ten absorption towers, and each set of PTFE evaporation membranes is 30m 2 . The vacuum pump is used to achieve the secondary evaporation function. The multi - stage centrifugal pump pressurizes the raw water and injects it into the reverse osmosis membrane element for purification treatment. The valve group is preferably a pneumatic valve group, which is used to control the reverse osmosis equipment to integrate different pneumatic valves and instruments in one unit, facilitating installation, commissioning, and maintenance.

[0039] Optionally, a regeneration system is also included. The regeneration system includes a regeneration pump, which chemically regenerates and cleans the membrane element after long - term use. The regeneration valve is linked with the regeneration pump and is used to open or close the chemical regeneration pipeline. A chemical regeneration storage tank, which is connected to the regeneration pump, is used to buffer part of the regeneration clear liquid for the chemical regeneration of the equipment.

[0040] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An oil and gas field water treatment system, characterized in that, Comprising: A pre-sedimentation treatment system, which at least includes a chemical dosing unit and a sedimentation tank unit for removing large particle sludge from wastewater; A filtration system, which is connected to the pre-sedimentation treatment system. The wastewater treated by the pre-sedimentation treatment system enters the filtration system. The filtration system at least includes a plurality of filtration modules with a precision of 1 - 5 μm for removing small particle impurities from wastewater; A security filter system, which is connected to the filtration system; A preheating system, which uses solar energy for power supply and preheats the wastewater; A thin film evaporation system, which is connected to the preheating system and is used for concentrating the wastewater.

2. The oil and gas field water treatment system according to claim 1, characterized in that, The pre-sedimentation treatment system includes the chemical dosing unit. The chemical dosing unit is arranged at one end of the sedimentation tank unit. A stirring unit is arranged at one end of the sedimentation tank, and inclined tube sedimentation fillers are arranged in the middle of the sedimentation tank unit.

3. The oil and gas field water treatment system according to claim 2, characterized in that, The chemical dosing unit includes a metering pump, which is connected to a chemical storage tank. The chemical dosing unit is used to add 0.01% PAC and 0.002% PAM to the sedimentation tank unit.

4. The oil and gas field water treatment system according to claim 1, characterized in that The filter system includes a plurality of filter module groups, and the filter module groups are connected to a clear liquid storage tank through a water outlet pipeline; A backwashing pipeline is also connected between the clear liquid storage tank and the filter module group, and the clear liquid storage tank can backwash the above filter module group; The filter module group is connected to a valve pump group, the clear liquid storage tank is connected to a sterilizer, and a water outlet is arranged on one side of the sterilizer.

5. The oil and gas field water treatment system according to claim 1, characterized in that, The security filter system includes a plurality of security filter groups, the security filter groups are connected to a supply pump, and the security filter groups are connected to a scale inhibitor dosing device.

6. The oil and gas field water treatment system according to claim 1, wherein The preheating system includes a solar heating module or an electric auxiliary heating module.

7. The oil and gas field water treatment system according to claim 1, wherein, The thin film evaporation system includes an evaporation equipment main body, which is connected to a vacuum pump, a multistage centrifugal pump, and a clear liquid buffer tank.

8. The oil and gas field water treatment system according to claim 6, characterized in that, The evaporation equipment main body includes a plurality of evaporation towers and a plurality of absorption towers.

9. The oil and gas field water treatment system according to claim 1, characterized in that, It also includes a fresh water tank, which is connected to the thin film evaporation system and is used to collect the clear liquid discharged from the thin film evaporation system.

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