CN221701168U - High-energy-efficiency oilfield produced water integrated treatment system - Google Patents

Abstract

The utility model discloses a high-energy-efficiency oilfield produced water integrated treatment system which comprises an oily sewage sedimentation filter and an oily sewage filtering coalescer which are connected in sequence: the oily sewage sedimentation filter comprises a filtering water tank, a sedimentation separation mechanism and a paper tape filtering mechanism; the sedimentation separation mechanism is arranged in the upper area of the filtering water tank, and the paper tape filtering mechanism is arranged on the filtering water tank; the oily sewage filtering coalescer comprises a shell and a filtering coalescing filter element group, wherein the shell comprises a filter element installation section, a water inlet flow distribution section and a buoyancy lift separation section. The technical scheme of the utility model uses the oily sewage sedimentation filter as front (pre) treatment equipment and uses the oily sewage filtering coalescer as rear (fine) treatment equipment, and the two are organically combined, so that the economical efficiency (low construction cost and low running cost) and the environmental protection performance (low energy consumption and low secondary oily waste production) of the system are improved while the system effectiveness (good effluent quality index and stable performance) is improved.

Description

A high-energy-efficiency integrated treatment system for oilfield produced water

Technical Field

The utility model relates to the technical field of oilfield produced water treatment, in particular to a high-energy-efficiency oilfield produced water integrated treatment system.

Background Art

Oilfield produced water is the oily wastewater separated from the produced fluid after dehydration during the oilfield exploitation process. It is also called oilfield oily wastewater or produced water.

Oilfield produced water is a complex multiphase system, containing petroleum substances, colloids, solid suspended particles, soluble salts, chemicals and other organic and inorganic substances. Its composition is complex and highly polluted. If these harmful substances are not effectively treated, they will be directly discharged into the surrounding environment, causing serious pollution to the soil, groundwater and water bodies. On the other hand, the amount of oilfield produced water is huge. After decades of exploitation, most of my country's oil fields have entered the late stage of high water content exploitation. The water content of produced fluid has exceeded 70%, and some oil fields are even above 90%. There are about more than 10 billion cubic meters of oilfield produced water that need to be treated every year in the country. After these sewages are treated to meet the standards, most of them are injected back into the formation as exploitation injection water, and a small part is discharged into the natural environment. By treating and reusing oilfield produced water, a large amount of water resources can be saved. Therefore, the treatment of oilfield produced water is of great significance for protecting the environment, saving water resources and promoting sustainable development.

The oilfield produced water treatment process usually includes a pre-treatment process (removing viscous suspended matter such as petroleum and colloids and solid suspended matter with larger particle size) and a post-treatment process (removing solid suspended matter with smaller particle size and emulsified petroleum substances).

The existing technical means for pre-treatment include natural sedimentation, hydrocyclone, air flotation, chemical flocculation, etc. The main problems of these technical means are:

1) Natural settlement: It takes a long time, the equipment is large, the floor space is large, and the construction cost is high;

2) Cyclone and flotation: high energy consumption, low operational flexibility, and greatly affected by flow fluctuations;

3) Chemical flocculation: Chemical agents need to be added, and a large amount of sludge and scum is produced;

4) The removal effect on viscous suspended solids (especially heavy viscous suspended solids) is very small, and the effluent water quality cannot provide effective protection for post-treatment (fine treatment).

5) The process flow is long, the system equipment has many stages, the system occupies a large area, and the system cost is high.

The existing technical means for post-processing (fine treatment) include: walnut shell filter, packing type coalescer, membrane treatment, etc. The main problems of these technical means are:

1) Walnut shell filter: The removal capacity of small-particle solid suspended matter and small-particle liquid suspended matter (emulsified oil) is limited. The water quality index of the treated effluent is difficult to meet the water quality standard of oil field reinjection water. Backwashing is required, the on-site operation volume is large, and secondary pollution (backwash water) will be generated.

2) Packing type coalescer: It is difficult to coalesce and separate small-particle solid suspension and small-particle liquid suspension (emulsified oil), and the water quality index of the treated effluent is difficult to meet the water quality standard of oilfield reinjection water;

3) Membrane treatment: It has a strong ability to remove small-particle solid suspended matter and small-particle liquid suspended matter (emulsified oil). The water quality index of the treated effluent can meet the water quality standard of oilfield reinjection water; however, it has high requirements for pre-treatment, the membrane is seriously polluted and needs to be cleaned, and the water treatment cost is extremely high.

The prior art "A method and system for treating oily wastewater based on filtration" (application number CN202110376330) discloses a technical solution for treating oily wastewater, as shown in FIG1. Although the technical solution solves the above-mentioned technical problems well, it still has the following problems:

(1) The treatment system consists of three stages of treatment equipment: a buffer filter, a cartridge filter, and a coalescing oil-water separator, as shown in Figure 1. The system has a long process, many equipment stages, a large area, and a high construction cost.

(2) The pre-treatment equipment is a buffer filtration device, which does not have the function of separating light viscous suspended matter and cannot fully adapt to the water quality characteristics and treatment requirements of oilfield produced water. The oil content of oilfield produced water is usually 500-20000 mg/L (ppm), and most of the petroleum substances contained in it exist in a suspended state (larger particle size), and only a small part exists in an emulsified state (smaller particle size); the petroleum suspended matter (crude oil, organic matter, colloid, sludge, etc.) in oilfield produced water is usually viscous. We call the petroleum suspended matter that can float upward in water (relying on its own buoyancy) light viscous suspended matter, and the petroleum suspended matter that cannot float upward is called heavy viscous suspended matter.

The light viscous suspended matter in the produced water of the oil field can be separated from the incoming water by natural sedimentation (floatation) to obtain recyclable floating oil (qualified crude oil). However, the existing buffer filtration device does not have the sedimentation (floatation) separation function of the light viscous suspended matter. During its working process, these light viscous suspended matter flows through the filter paper belt with the water flow under the suction action of the pump, causing contamination and clogging of the filter paper belt, which not only shortens the service life of the filter paper belt, but also greatly increases the amount of secondary oily waste generated (the light viscous suspended matter is originally recyclable qualified crude oil, and becomes secondary oily waste when it is contaminated on the filter paper belt);

(3) Post-processing equipment includes two-stage equipment, namely, cartridge filter and coalescing oil-water separator. Both of these equipment are cartridge filter equipment, which requires frequent replacement of filter cartridges. The replacement cycle of the filter cartridges of the two-stage filter equipment is short, the replacement workload is large, and the replacement cost is high (material consumption cost and operation cost).

(4) The post-processing equipment consists of two stages: a cartridge filter and a coalescing oil-water separator, and its average operating pressure difference is high. The operating pressure difference of the cartridge filter is 5 to 260 KPa, and its average operating pressure difference is 132.5 KPa. The operating pressure difference of the coalescing oil-water separator is 5 to 100 KPa, and its average operating pressure difference is 102.5 KPa. The average operating pressure difference of the two combined is 235 KPa. A high operating pressure difference will inevitably lead to high operating energy consumption.

(5) The removal effect of the coalescing oil-water separator on small-size oil droplets (especially emulsified oil) needs to be further improved.

Therefore, it is necessary to design a high-energy-efficiency integrated oilfield produced water treatment system to solve the above problems.

Utility Model Content

The purpose of the utility model is to provide a high-energy-efficiency integrated treatment system for oilfield produced water, which has the advantages of short process flow, low construction cost, good treatment effect (good and stable water quality indicators of effluent), long filter element replacement cycle, low operating energy consumption and operating cost, and simple operation and maintenance.

In order to achieve the above purpose, the utility model adopts the following technical solutions:

The high-efficiency oilfield produced water integrated treatment system includes an oily wastewater sedimentation filter and an oily wastewater filtration coalescer connected in sequence, wherein:

The oily wastewater sedimentation filter comprises a filter water tank, a sedimentation separation mechanism and a paper belt filter mechanism. The sedimentation separation mechanism is arranged in the upper area of the filter water tank, and the paper belt filter mechanism is installed on the filter water tank.

Furthermore, the filtered water tank is a rectangular structure, with a paper inlet on the left side and a paper outlet on the right side, and a first water inlet and a first water outlet are provided at appropriate positions of the filtered water tank.

Furthermore, the paper tape filter mechanism includes a filter paper tape roll, a filter paper tape, a filter paper tape paper removal mechanism and a waste paper storage box, and the filter paper tape roll and the waste paper storage box are installed outside the filter water tank. The filter paper tape enters from the paper inlet, passes horizontally through the inner cavity of the filter water tank, and leaves the filter water tank from the paper outlet. The filter paper tape divides the inner cavity of the filter water tank into a water inlet area and a water outlet area. The upper area of the filter paper tape is the water inlet area, and the lower area of the filter paper tape is the water outlet area. The water inlet area is provided with the first water inlet, and the water outlet area is provided with the first water outlet.

Furthermore, the sedimentation and separation mechanism includes a sedimentation/floating separation zone, an oil floating baffle and an oil skimming mechanism. The inner cavity of the filtered water tank is provided with a water inlet zone and a water outlet zone, and the oil floating baffle is arranged in the water inlet zone; the oil floating baffle includes a left baffle and a right baffle, and the area between the two oil floating baffles is the sedimentation (floating) separation zone, and the oil skimming mechanism is installed above the sedimentation/floating separation zone.

Specifically, the first water inlet is arranged at the lower inner side of the left partition of the sedimentation/floatation separation zone; the first water inlet is arranged horizontally and communicated with the sedimentation/floatation separation zone; the first water inlet is arranged above the filter paper belt. The first water outlet is arranged at the lower part of the water outlet zone and close to the paper outlet side. The relative positions of the first water inlet and the first water outlet should ensure that the oily wastewater flows from left to right and downward in the sedimentation/floatation separation zone.

Specifically, the skimming mechanism is installed on the upper inner side of the partition on the right side of the settling/floating separation zone, and is used to extract the floating oil from the settling/floating separation zone. The position of the skimming mechanism should be as far away from the first water inlet as possible, and the relative position of the first water inlet and the skimming mechanism should be set to ensure that the floating oil flows from left to right and upward at the same time.

Specifically, the filter paper tape enters the filter water tank from the left side partition of the sedimentation/floatation separation zone, and leaves the filter water tank from the right side partition of the sedimentation/floatation separation zone, preventing the floating oil on the upper part of the sedimentation/floatation separation zone from contaminating the filter paper tape during the process of entering and leaving the filter water tank.

Furthermore, it also includes a centrifugal pump, which is connected to the first water outlet through a pipeline.

Furthermore, the filter paper roll and the filter paper belt paper removal mechanism are respectively located on both sides of the filter water tank, and the waste paper storage box is arranged below the paper outlet.

The working process and working principle of the oily sewage sedimentation filter are:

The sedimentation filter completes two working processes: sedimentation/floatation separation and paper tape filtration. The first is the sedimentation/floatation separation process, where the influent (such as oilfield produced water) enters the sedimentation/floatation separation zone through the first water inlet and then flows from left to right. In this process, the light viscous suspended matter (crude oil, organic matter, sludge) in the influent water floats up by its own buoyancy, forming floating oil on the water surface of the sedimentation/floating separation zone, and the floating oil is extracted by the skimming mechanism. Through this process, the light viscous suspended matter is separated from the influent water, and the floating oil is recovered; the second is the paper tape filtration process, in which the heavy suspended matter (which cannot float in the water) in the influent water settles to the surface of the filter paper tape under the carrying of water, and then flows downward through the filter paper tape under the suction action of the centrifugal pump, and the heavy viscous suspended matter (which cannot float in the water) and large-particle-size solid suspended matter are intercepted by the filter paper tape, and the effluent after filtration by the filter paper tape enters the water outlet area, and finally, the filtered effluent is extracted through the first water outlet by a centrifugal pump. Through this process, the heavy viscous suspended matter and large-particle-size solid suspended matter are separated from the influent water. Through the above two working processes, the oily wastewater sedimentation filter effectively removes the viscous suspended matter (light and heavy) and large-particle solid suspended matter in the influent water, making the SDI of the effluent water quality ≤5, providing effective protection for the post-treatment process.

During the filtration process of the filter paper belt, as the amount of sewage passing through increases, the amount of viscous suspended solids intercepted and contaminated by the filter paper belt increases continuously, causing the pressure difference (filtration resistance) of the filter paper belt to gradually increase, resulting in a gradual decrease in the vacuum degree of the outlet area; when the vacuum degree of the outlet area drops to the set value, an instruction is issued to the filter paper belt paper feeding mechanism to allow the filter paper belt paper feeding mechanism to automatically feed the new filter paper belt into the filter water tank, and send the contaminated filter paper belt to the waste paper storage box, thereby realizing the automatic replacement of the filter paper belt and entering the next working cycle. This design does not require shutdown during the replacement of the filter paper belt.

The technical effects of the oily wastewater sedimentation filter are:

1) By using the principle of sedimentation and buoyancy, the light viscous suspended matter is first separated from the influent water, which not only effectively recovers the floating oil (qualified crude oil), but also avoids the pollution (contamination) of the filter paper tape by the light viscous suspended matter, thereby extending the service life of the filter paper tape and reducing the amount of secondary oily waste generated; compared with the technical solution disclosed in the comparative document (CN216259472U), as shown in Figure 1, the existing buffer filter device does not have the separation function of light viscous suspended matter, and the light suspended matter causes serious contamination and blockage to the filter paper tape, which not only shortens the service life of the filter paper tape, but also increases the amount of secondary oily waste generated (the light viscous suspended matter is originally qualified crude oil that can be recovered, and it becomes secondary oily waste when it is contaminated on the filter paper tape). Compared with the existing buffer filter device, the service life of the filter paper tape of this technical solution is extended by more than two times, and the amount of secondary oily waste generated is reduced by 60%.

2) The use of two floating oil baffles effectively prevents floating oil from contaminating the filter paper belt, further reducing the amount of secondary oily waste generated;

3) The combination of shallow pool sedimentation (natural sedimentation) and paper tape filtration (forced sedimentation) improves the working efficiency and treatment effect of oily wastewater treatment. After floating separation and paper tape filtration, the viscous suspended solids contained in the oily wastewater are effectively removed, and the SDI of the effluent water quality is ≤5, which provides effective protection for the post-treatment process.

The oily wastewater filtration coalescer comprises a filtration coalescing filter element group, a shell and an end cover:

The filter coalescing filter element group includes multiple filter coalescing filter elements. The filter coalescing filter elements flow from the inside to the outside, and their designed surface flow velocity is ≤0.001m/s. When designing the filter coalescing device, the number of filter elements (total filter area) should be calculated and determined based on this (surface flow velocity ≤0.001m/s); filter coalescing filter elements with small flow resistance and large pollution holding capacity should be selected, and their initial pressure difference is ≤2KPa, the allowable working pressure difference is ≤60KPa, and the apparent pollution holding capacity is ≥5200g/(L/min).

Furthermore, the filter-coalescing filter element comprises a filter combination layer, a skeleton and a coalescing combination layer which are arranged in sequence, the filter combination layer is folded and arranged on the inner side of the skeleton, and the coalescing combination layer is wound and arranged on the outer side of the skeleton in sequence. The unfolded area of the folded filter combination layer is more than 3 times the outer surface area of the filter-coalescing filter element.

The shell includes a filter element installation section, a water inlet distribution section, and a buoyancy separation section; the shell also includes a second water inlet, a second water outlet and an oil collecting bag, the second water inlet is arranged on the water inlet distribution section, the second water inlet is connected to the inside of the water inlet distribution cavity, the second water outlet is arranged at the lower right of the buoyancy separation section, the oil collecting bag is arranged at the upper right of the buoyancy separation section, the second water outlet and the oil collecting bag are both connected to the inner cavity of the buoyancy separation section; the second water outlet should be as far away from the oil collecting bag as possible.

Furthermore, a water inlet distribution cavity is provided at the upper part of the inner cavity of the water inlet distribution section, and a crescent-shaped flow channel is provided at the lower part, and the crescent-shaped flow channel connects the filter element installation section and the floating separation section.

Specifically, the water inlet distribution cavity is composed of a mounting tube sheet, a vertical partition, a horizontal partition and an outer cylinder. The mounting tube sheet is provided with a plurality of filter element mounting seats, each of which is provided with an internal flow channel to connect the water inlet distribution cavity with the interior of the filter coalescing filter element. The outer cylinder is provided with a second water inlet, which is connected with the interior of the water inlet distribution cavity.

The filter coalescing filter element group is installed in the cylinder of the filter element installation section, and the filter coalescing filter element is installed on the corresponding filter element installation seat. The filter coalescing filter element includes a free end (sealed end) and an installation end (water inlet end). The free end of the filter coalescing filter element is sealed, and the free end of the filter coalescing filter element faces the end cover of the housing; the installation end of the filter coalescing filter element is sealed and connected to the filter element installation seat, and its interior is connected to the water inlet distribution cavity.

Optionally, a separation element that blocks oil and allows water to pass may be provided in the floating separation section, and the separation element includes a blade separator or a separation filter element.

The oily wastewater filter coalescer can effectively remove fine solid particles and fine liquid particles (emulsified oil) in the oily wastewater. Its working process and working principle are as follows:

The inlet water (oil-containing sewage) enters the inlet distribution cavity through the second water inlet, and then flows into the interior of the filtering and coalescing filter element from the internal channel of the filter element mounting seat.

In the filter-coalescing filter element, the incoming water flows from the inside to the outside through the filter-coalescing filter element, completing the two working processes of filtration and coalescence: first, the incoming water flows through the folded precision filtration layer, and the fine solid particles are intercepted by the precision filtration layer; then, the filtered effluent flows to the coalescence layer, and in the process of flowing through the coalescence layer, the fine liquid particles (emulsified oil) are coalesced into larger oil droplets (oil beads), and the coalesced and grown oil droplets (oil beads) flow out from the outer surface of the filter-coalescing filter element and enter the filter element installation section. In the process of oily sewage flowing through the filter-coalescing filter element, fine solid suspended matter is retained inside the filter element, while fine liquid suspended matter (emulsified oil) is coalesced and grown into larger oil droplets (oil beads).

Inside the cylinder of the filter element installation section, the coalesced oil droplets float up by their own buoyancy (oil is lighter than water), achieving the first floating separation: inside the filter coalescing filter element, the water flow before coalescing flows from right to left, and outside the coalescing filter element, the water flow after coalescing flows from left to right, so the entire internal space and length of the filter element installation section can be used for floating separation.

The oil droplets that fail to float and separate in the filter element installation section are carried by the water flow through the crescent-shaped flow channel at the upper part of the water inlet distribution cavity and enter the floating separation section.

Inside the cylinder of the flotation separation section, water flows in from the top and continues to flow from left to right; in this process, due to the difference in specific gravity between oil and water, water sinks downward while oil droplets float upward, achieving a second flotation separation.

The oil droplets after buoyancy separation gather into the oil collecting bag and are discharged from the oil discharge port. At the same time, the water flow after buoyancy separation flows to the right side of the buoyancy separation section and flows out through the second water outlet to obtain clean water.

In the above working process, the oily wastewater is filtered, agglomerated and separated by floating, and the fine solid particles and fine liquid particles (emulsified oil) are effectively removed. The water quality indicators of the effluent can reach: oil content ≤5ppm, SS content ≤1mg/L.

During the operation of the system (equipment), as the amount of sewage passing through increases, the particulate pollutants intercepted by the filter coalescing element continue to increase, and the operating pressure difference of the filter element will gradually rise. When the operating pressure difference of the filter element reaches the specified allowable working pressure difference, it is necessary to stop the system and replace the filter element. In this technical solution, the specified allowable working pressure difference is 60KPa.

The technical effects of the oily wastewater filter coalescer are:

(1) Significantly extend the filter element replacement cycle of the filter coalescer, significantly reduce the filter element replacement cost and replacement workload, and thus significantly reduce the equipment operating cost (filter element replacement cost)

In order to extend the replacement cycle of the filter coalescing filter element, the main technical measures taken are:

① Use apparent dirt holding capacity to evaluate the filter element's performance (service life)

During the operation of the filter coalescer, as the amount of water treated increases, the filter element (filter coalescing element) in the equipment will gradually increase the pressure difference due to the increase in the trapped particulate pollutants. When the pressure difference reaches the specified allowable working pressure difference, the filter coalescing element needs to be replaced. The operating time from the start of the filter element to the time when the working pressure difference reaches the specified allowable working pressure difference is called the filter element replacement cycle (service life), which is usually expressed in months or days (such as 180 days or 6 months).

The filter element replacement cycle (service life) is closely related to the particle content upstream and the performance of the filter element itself (apparent dirt holding capacity):

T＝D/43.2C

Where: T: Service life (the working time before the filter element reaches the specified allowable working pressure difference △P. Unit: month)

D: Apparent dirt holding capacity (the capacity of the filter element to hold dirt before reaching the specified allowable working pressure difference △P. Unit: g/(L/min))

C: upstream particulate matter content (unit: mg/L);

In the prior art, the filter element replacement cycle (service life) is usually used as a technical indicator to evaluate the performance of the filter element, which is not accurate enough. This is because the filter element replacement cycle is not only related to the performance of the filter element itself, but also to the concentration of particulate pollutants upstream of it. For the same filter element, if the concentration of particulate pollutants upstream is high, the filter element replacement cycle is short; if the concentration of particulate pollutants upstream is low, the filter element replacement cycle is long.

In order to avoid the above problems, this technical solution uses the apparent dirt holding capacity as a technical indicator for evaluating the performance of the filter element. The apparent dirt holding capacity refers to the capacity of the filter element to hold pollutants before the operating pressure difference reaches the specified allowable working pressure difference. The apparent dirt holding capacity is only related to the performance of the filter element itself, and has nothing to do with the content of upstream particulate matter. Using the apparent dirt holding capacity as an evaluation indicator for the service life of the filter element is more accurate and scientific.

② Use a filter element with large dirt holding capacity (apparent dirt holding capacity ≥ 5200g/(L/min))

When the upstream particulate pollutants are constant, the greater the apparent pollution holding capacity of the filter element, the longer its service life. This technical solution clearly stipulates that a filter coalescing filter element with a large pollution holding capacity should be selected, and its apparent pollution holding capacity should be ≥5200g/(L/min); when the content of upstream particulate matter is 10mg/L, the filter element replacement cycle is 12 months. The filter coalescing filter element selected in the prior art solution has an apparent pollution holding capacity of ≤420g/(L/min). When the content of upstream particulate matter is 10mg/L, the filter element replacement cycle is less than 1 month; obviously, the filter element replacement cycle of this technical solution is more than 12 times longer than that of the prior art solution. The replacement cost of the filter element includes the purchase cost, labor cost and downtime loss. The extension of the filter element replacement cycle not only saves the purchase cost, but also greatly reduces the labor cost and downtime loss. Since the replacement of the filter element requires downtime operation, and the shell and pipeline are drained and filled with water, the replacement operation cost is greater than the purchase cost of the filter element. The use of a filter coalescing filter element with a large dirt holding capacity can significantly extend the filter element replacement cycle, thereby significantly reducing the filter element replacement cost (purchase cost, labor cost, and downtime loss).

③Increase the filter area of the filter element and reduce the filter speed of the filter element

The relationship between the dirt holding capacity (D) of the filter element and its filtration area (S) is: D = (S ₁ /S ₂ ) ⁿ , where 1≤n≤2. When the filtration area is doubled, its dirt holding capacity can be increased by 2.4 to 2.8 times. In this technical solution, the filter combination layer inside the filter coalescing filter element adopts a folded structure, and its unfolded filtration area is more than 3 times the outer surface area of the filter coalescing filter element, and its dirt holding capacity is increased by 4-5 times;

The relationship between the dirt holding capacity (D) of the filter element and its filtration speed (V) is: D = (V ₂ /V ₁ ) ⁿ , where 1≤n≤2. When the filtration speed of the filter element is reduced by 1/2, its dirt holding capacity can be increased by 2.6 to 3.2 times. In this technical solution, the surface flow rate of the filtration coalescing filter element is 0.001m/s, which is 1/5 of the existing technology (0.005m/s). This means that when the structure and size of the filter element are constant, its dirt holding capacity is 9 to 11 times that of the existing technical solution.

At the same time, two technical measures, namely increasing the filtration area and reducing the surface flow velocity, are adopted to greatly improve the pollution holding capacity of the filter coalescing filter element, so that the pollution holding capacity of the filter coalescing filter element is ≥5200g/(L/min).

(2) Reduce the operating energy consumption and energy cost of the equipment

The filter coalescer will generate a pressure difference (filtration resistance) during operation, and power is required to overcome the pressure difference and allow water to flow through the filter coalescer. The relationship between the operating energy consumption of the filter coalescer and the operating pressure difference is: N = Q*ΔP (where N: operating energy consumption; Q: working flow; ΔP: operating pressure difference).

When the working flow of the equipment is constant, the greater the average operating pressure difference of the equipment, the higher its operating energy consumption. The technical solution clearly stipulates that the initial pressure difference of the filter coalescer is ≤2Kpa, the allowable working pressure difference is ≤60KPa, and its average operating pressure difference is 31Kpa; the operating pressure difference of the filter coalescer shell is about 1KPa. Adding the two together, the average operating pressure difference of the equipment assembly is 32KPa; while in the prior art, the operating pressure difference of the filter coalescer is usually 10-120KPa, and the average operating pressure difference is 65KPa. According to N=Q*ΔP, when the system working flow (Q) is the same, the operating energy consumption of the filter coalescer of the technical solution is 49% of the operating energy consumption of the prior art solution, that is, the energy consumption is saved by 51%.

The relationship between the working pressure difference and flow rate of the filter element is: ΔP∝V (ΔP: operating pressure difference; V: flow rate on the filter element surface). A reduction in flow rate will inevitably reduce the operating pressure difference. In this technical solution, the surface flow rate of the filtration coalescing filter element is 0.001m/s, which is 1/5 of the existing technology (0.005m/s). Then its operating pressure difference will also be 1/5 of the existing technology. It is completely feasible to reduce the average operating pressure difference from 65KPa (10-120KPa) to 32KPa.

The reduction in the filtration speed of the filter element leads to a reduction in the operating pressure difference of the equipment, which in turn leads to a reduction in the operating energy consumption and energy costs of the equipment.

(3) Improved the filtering performance and oil removal performance of the equipment (especially fine-sized solid suspended matter and fine-sized emulsified oil)

In order to improve the oil removal effect of the filter coalescer (especially the emulsified oil with fine particle size), the technical measures adopted in this technical solution are:

① The filter element with the filter flowing from inside to outside is adopted. The water flows from inside to outside, which is conducive to the coalescence and growth of oil droplets on the outer surface of the coalescence filter element. The oil droplets after coalescence are larger in size, which is conducive to the subsequent floating separation;

② The surface flow rate of the filter coalescing filter element is reduced. The coalescing effect of the filter coalescing filter element is closely related to its surface flow rate. Reducing the surface flow rate can significantly improve the coalescing effect of the oil droplets. The lower the flow rate, the larger the size of the oil droplets after coalescing. The designed surface flow rate (≤0.001m/s) of the utility model is 1/5 of that of the prior art (≤0.005m/s). The substantial reduction in surface flow rate will significantly improve the coalescing effect of the oil droplets (especially the emulsified oil with fine particle size) (the oil droplets after coalescing will be larger in size), which is beneficial to improving the separation efficiency of the subsequent floating separation process.

③ The design of the internal structure and internal flow field of the shell has been improved. By setting the water inlet distribution section and the crescent-shaped flow channel, the flow field inside the shell has been changed, so that the coalesced oil droplets can make full use of the internal space of the cylinder for floating (filter element installation section and floating separation section). The coalesced oil droplets achieve two floating separations in the shell, with sufficient floating separation and good floating separation effect.

By adopting the above three technical measures at the same time, the filtration performance and oil removal performance of the oily wastewater filtration coalescer are significantly improved, so that the effluent water quality indicators reach: oil content ≤5ppm, SS ≤1mg/L.

In summary, the high-efficiency integrated treatment system for produced water from oilfields of the utility model uses the oily wastewater sedimentation filter as the pre-treatment equipment to first remove viscous suspended matter (light and heavy) and solid suspended matter with larger particle size, and uses the oily wastewater filtration coalescer as the post-treatment equipment to further remove solid suspended matter with fine particle size and liquid suspended matter with fine particle size (emulsified oil). The organic combination of the two improves the system's effectiveness (good effluent water quality indicators and stable performance) while improving the system's economy (low construction cost, low operating cost) and environmental performance (low energy consumption and less secondary oily waste generation). Specifically, the utility model system has the following advantages:

(1) Effectively recover crude oil (floating oil) from produced water in oil fields, and the system generates little secondary oily waste;

(2) The replacement cycle of filter paper belts and filter coalescing filter elements is long, and the replacement workload and replacement cost of filter elements are low;

(3) The operating pressure difference of the post-processing (fine processing) equipment is small and the operating energy consumption is low;

(4) The system has stable working performance and good effluent quality, and the effluent quality can reach: oil content ≤5ppm, SS ≤1mg/L;

(5) The system consists of only two levels of processing equipment, with fewer equipment levels, shorter process flow, smaller footprint, lower cost, and easier operation and maintenance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a process flow of the prior art;

FIG2 is a schematic diagram of the process flow of the utility model;

FIG3 is a schematic diagram of the structure of the oily wastewater sedimentation filter in the utility model;

FIG4 is a schematic diagram of the structure of the oily wastewater filter coalescer in the utility model;

FIG5 is a schematic diagram of the structure of the oily wastewater filter coalescer with a blade separator in the utility model;

FIG6 is a schematic diagram of the structure of the oily wastewater filter coalescer containing a separation filter element in the utility model;

FIG7 is a schematic diagram of the three-dimensional structure of the water inlet flow distribution section of the utility model;

FIG8 is a schematic diagram of the main structure of the water inlet distribution section of the utility model;

FIG9 is a schematic diagram of the top view of the structure of the water inlet distribution section in the utility model;

FIG10 is a schematic diagram of the water flow direction of the water inlet distribution section of the utility model;

FIG. 11 is a schematic diagram of the structure of the filtering and coalescing filter element in the present invention.

FIG12 is an enlarged schematic diagram of the local structure of point A in FIG11 of the present invention;

FIG. 13 is a schematic diagram of the water flow direction of the filtering coalescing filter element in the present invention.

FIG. 14 is a schematic diagram showing the calculation of the filtration area of a pleated filter layer and a cylindrical filter layer.

In the figure: 1-oil-containing sewage sedimentation filter; 11-filter water tank; 111-first water inlet; 112-first water outlet; centrifugal pump 113; 12-sedimentation separation mechanism; 121-floating separation zone; 122-floating oil partition; 123-oil skimming mechanism; 13-paper tape filtering mechanism; 131-filter paper tape roll; 132-filter paper tape; 133-filter paper tape paper mechanism; 134-waste paper storage box; 2-oil-containing sewage filter coalescer; 21-housing; 211-filter element installation section; 212-water inlet distribution section; 2 121-water inlet distribution cavity; 21211-mounting tube sheet; 21212-vertical partition; 21213-horizontal partition; 21214-filter element mounting seat; 2122-crescent-shaped flow channel; 213-floating separation section; 2131-blade separator; 2132-separation filter element; 214-second water inlet; 215-second water outlet; 216-oil collecting bag; 22-filter coalescing filter element group; 221-filter coalescing filter element; 2211-filter combination layer; 2212-skeleton; 2213-coalescence combination layer.

DETAILED DESCRIPTION

In order to more clearly illustrate the technical solutions in the embodiments of the utility model or the prior art, the utility model will be briefly introduced below in combination with the drawings and the description of the embodiments or the prior art. Obviously, the following description of the structure of the drawings is only some embodiments of the utility model. For ordinary technicians in this field, other drawings can also be obtained based on these drawings without creative work. It should be noted that the description of these embodiments is used to help understand the utility model, but does not constitute a limitation of the utility model.

The utility model is further described below in conjunction with Figures 2-12:

Example 1

This embodiment provides a high-efficiency oilfield produced water integrated treatment system, as shown in FIG2 , comprising an oily wastewater sedimentation filter 1 and an oily wastewater filter coalescer 2 connected in sequence, wherein:

As shown in FIG. 3 , in this embodiment, the oily wastewater sedimentation filter 1 includes a filter water tank 11 , a sedimentation separation mechanism 12 and a paper belt filter mechanism 13 , wherein the sedimentation separation mechanism 12 is arranged in the upper area of the filter water tank 11 , and the paper belt filter mechanism 13 is installed on the filter water tank 11 .

As shown in Figure 3, in this embodiment, the sedimentation and separation mechanism 12 includes a sedimentation (floating) separation area 121, an oil floating baffle 122 and an oil skimming mechanism 123. The inner cavity of the filtered water tank 11 is provided with a water inlet area and a water outlet area, and the oil floating baffle 122 is arranged in the water inlet area; the oil floating baffle 122 includes a left baffle and a right baffle, and the area between the two oil floating baffles is the sedimentation (floating) separation area 121, and the oil skimming mechanism 123 is installed above the sedimentation (floating) separation area 121.

In this embodiment, the sedimentation separation mechanism 12 has the function of separating light viscous suspended matter from the oily wastewater and recovering floating oil, and the paper tape filtering mechanism 13 has the function of removing heavy viscous suspended matter and large-particle solid suspended matter from the oily wastewater. The oily wastewater sedimentation filter 1 has the dual function of removing viscous suspended matter (light and heavy) and large-particle solid suspended matter. As a pre-treatment of oilfield produced water, its effluent is the first effluent, and the water quality indicators of the first effluent should be able to meet the following requirements: SDI ≤ 5, oil content ≤ 50 ppm, SS ≤ 10 mg/L. The viscous suspended matter in the produced water of the oil field will cause rapid clogging and pollution of the filter coalescing filter element 221. The viscous suspended matter is the natural enemy of the filter coalescing filter element 221. The oily wastewater sedimentation filter 1, as a pre-treatment equipment, can effectively remove the viscous suspended matter in advance, significantly improve the effluent water quality indicators (especially SDI), make the use of precision filtration coalescing filter element possible, and significantly extend the service life and replacement cycle of the filter coalescing filter element 221, thereby improving the effectiveness and economy of the operation of the oily wastewater coalescer 2.

As shown in FIG4 , in this embodiment, the oily wastewater filtration coalescer 2 comprises a filtration coalescing filter element group 22, a housing 21 and an end cover:

In this embodiment, the filter coalescing filter element group 22 includes a plurality of filter coalescing filter elements 221, and the filter coalescing filter elements 221 flow from inside to outside, and the designed surface flow velocity is 0.001 m/s;

In this embodiment, a filter coalescing filter element with low flow resistance and large dirt holding capacity is selected, and its initial pressure difference is 1KPa, the allowable working pressure difference is 60KPa, and the dirt holding capacity is 5800g/(L/min).

As shown in FIG. 4 , in this embodiment, the housing 21 includes a filter element installation section 211, a water inlet distribution section 212 and a floating separation section 213, the lower part of the inner cavity of the water inlet distribution section 212 is provided with a water inlet distribution cavity, and the upper part is provided with a crescent-shaped flow channel 2122, and the crescent-shaped flow channel 2122 connects the inner cavity of the filter element installation section 211 with the inner cavity of the floating separation section 213;

As shown in FIG. 4 , in this embodiment, the filtering and coalescing filter element group 22 is installed in the filter element installation section 211 of the housing 21 .

In this embodiment, the influent (oilfield produced water) first enters the sedimentation separation mechanism, which separates the light viscous suspended matter from the influent and recovers the floating oil; then, the viscous suspended matter that cannot be separated by floating flows downward through the paper belt filter mechanism under the carry-over of the water flow, and the paper belt filter mechanism separates the heavy viscous suspended matter and the solid suspended matter with larger particle size to obtain the first effluent; the water quality index of the first effluent reaches: SDI≤4, oil content≤30ppm, SS≤8mg/L, providing effective protection for the post-(fine) treatment process; then, the first effluent flowing out of the oily wastewater sedimentation filter flows into the oily wastewater filter coalescer, and the oily wastewater filter coalescer effectively removes the solid suspended matter with fine particle size and the liquid suspended matter with smaller particle size (emulsified oil), to obtain qualified second effluent, and the water quality index of the second effluent reaches: oil content≤5ppm, SS≤1mg/L.

The technical solution disclosed in the comparative document (CN202110376330) is shown in FIG1 , and its treatment system includes a buffer filtration device, a cartridge filter, and a coalescing oil-water separator three-stage treatment equipment. Compared with the comparative document (CN202110376330), the technical solution provided in this embodiment has the following advantages:

(1) It can effectively recover crude oil (floating oil) in the produced water of the oil field, and the amount of secondary oily waste generated by the system is small;

(2) The replacement cycle of filter paper belts and filter coalescing filter elements is long, and the replacement workload and replacement cost of filter elements are low;

(3) The operating pressure difference of the post-processing (fine processing) equipment is small and the operating energy consumption is low;

(4) The system has stable working performance and good effluent quality, and the effluent quality can reach: oil content ≤5ppm, SS ≤1mg/L;

(5) The system consists of only two levels of processing equipment, with fewer equipment levels, shorter process flow, smaller footprint, lower cost, and easier operation and maintenance.

Example 2

This embodiment provides an oily wastewater sedimentation filter, as shown in Figure 3, including a filter water tank 11, a sedimentation separation mechanism 12 and a paper belt filter mechanism 13, the sedimentation separation mechanism 12 is arranged in the upper area of the filter water tank 11, and the paper belt filter mechanism 13 is installed on the filter water tank 11.

As shown in FIG. 3 , in this embodiment, the filtered water tank 11 is a rectangular structure, with a paper inlet 113 on the left side and a paper outlet 114 on the right side, and a water inlet 111 and a water outlet 112 are provided at appropriate positions of the filtered water tank 11 .

As shown in Fig. 3, in this embodiment, the paper tape filter mechanism 13 includes a filter paper tape roll 131, a filter paper tape 132, a filter paper tape paper removal mechanism 133 and a waste paper storage box 134. The filter paper tape roll 131 and the waste paper storage box 134 are installed outside the filter water tank 11. The filter paper tape 132 enters from the paper inlet 113, passes through the filter water tank 11 horizontally, and leaves the filter water tank 11 from the paper outlet 114. The filter paper tape 132 divides the filter water tank into a water inlet area and a water outlet area. The upper area of the filter paper tape is the water inlet area, and the lower area of the filter paper tape 132 is the water outlet area. The water inlet area is provided with a water inlet 112, and the water outlet area is provided with a water outlet 112.

In this embodiment, the filter paper tape 131 is a polypropylene non-woven fabric or a polyester non-woven fabric filter paper, the filtering accuracy of which is 1-15 μm, and the longitudinal tension thereof is greater than 300 N/5 cm.

As shown in FIG3 , in this embodiment, the sedimentation separation mechanism 12 includes a sedimentation (floating) separation area 121, an oil floating baffle 122 and an oil skimming mechanism 123; an oil floating baffle 122 is provided in the water inlet area, the oil floating baffle 122 includes a left baffle and a right baffle, the area between the two oil floating baffles is the sedimentation (floating) separation area 121, and the oil skimming mechanism 123 is installed above the sedimentation (floating) separation area 121. The sedimentation separation mechanism 12 can effectively separate light viscous suspended matter from the inlet water.

As shown in FIG3 , in this embodiment, the water inlet 111 is arranged at the lower inner side of the left partition of the sedimentation (floating) separation zone; the water inlet 111 is arranged horizontally and communicated with the sedimentation (floating) separation zone; the water inlet 111 is arranged above the filter paper belt 32. The water outlet 112 is arranged at the lower part of the water outlet zone and close to the paper outlet 114; in the sedimentation (floating) separation zone, the incoming water flows from left to right (and downward at the same time).

As shown in Fig. 3, in this embodiment, the skimming mechanism 123 is installed on the upper inner side of the right side partition of the settling (floating) separation zone 121, and is used to extract the floating oil from the settling (floating) separation zone 121. The position of the skimming mechanism 123 is far away from the water inlet 111, which increases the settling (floating) distance.

In this embodiment, the influent water (e.g., produced water from an oil field) enters the sedimentation (floating) separation zone through the water inlet 111, and then flows from left to right. In this process, the light viscous suspended matter (crude oil, organic matter, oil sludge) in the influent water floats up by its own buoyancy, forming floating oil on the water surface of the sedimentation (floating) separation zone, and the floating floating oil is extracted by the skimming mechanism 123; the heavy suspended matter in the influent water (which cannot float in water) settles to the surface of the filter paper belt 132 under the carrying of water, and then flows downward through the filter paper belt 132 under the suction action of the centrifugal pump 14, and the heavy suspended matter (which cannot float in water) is intercepted by the filter paper belt 132, and the effluent water after being filtered by the filter paper belt 132 enters the water outlet zone. Finally, the filtered effluent water is extracted through the water outlet 112 by the centrifugal pump 14. The oily wastewater completes two working processes in the sedimentation filter: sedimentation (floatation) separation and paper tape filtration. The viscous suspended matter (light and heavy) and large-particle solid suspended matter are effectively removed, making the SDI of the effluent water quality ≤5, providing effective protection for the post-treatment process.

In this embodiment, during the working process of the filter paper belt 132, as the amount of sewage passing through increases, the amount of viscous suspended matter intercepted and contaminated by the filter paper belt 132 increases continuously, causing the pressure difference (filtration resistance) of the filter paper belt 132 to gradually increase, resulting in a gradual decrease in the vacuum degree of the water outlet area; when the vacuum degree of the water outlet area drops to a set value, an instruction is issued to the filter paper belt paper feeding mechanism 133, allowing the filter paper belt paper feeding mechanism 133 to automatically feed the paper, drag the new filter paper belt into the filter water tank 11, and drag the contaminated filter paper belt out of the filter water tank 11 and send it to the waste paper storage box 134, thereby realizing the automatic replacement of the filter paper belt and entering the next working cycle. During the paper belt replacement operation, there is no need to stop the machine.

In this embodiment, the filter paper belt enters the filter water tank 11 from the left side partition of the sedimentation (floatation) separation zone, and leaves the filter water tank 11 from the right side partition of the sedimentation (floatation) separation zone, preventing the floating oil on the upper part of the sedimentation (floatation) separation zone from contaminating the filter paper belt 132 during the process of the filter paper belt 132 entering and leaving the filter water tank 11.

As shown in FIG. 3 , this embodiment further includes a centrifugal pump 14 , which is connected to the water outlet 112 through a pipeline.

As shown in FIG. 3 , in this embodiment, the filter paper roll 131 and the filter paper removing mechanism 133 are respectively located on both sides of the filter water tank 11 , and the waste paper storage box 134 is disposed below the paper outlet 114 .

The working process of this embodiment is:

The influent (oilfield produced water) enters the sedimentation (floating) separation zone 121 of the filter water tank through the water inlet 111; in the sedimentation (floating) separation zone 121, the influent flows from left to right. In this process, the light viscous suspended matter (crude oil, organic matter, oil sludge) in the influent floats up by its own buoyancy, forming floating oil on the water surface of the sedimentation (floating) separation zone 121, and the floating floating oil is extracted by the skimming mechanism 123; the heavy suspended matter in the influent (which cannot float in water) settles to the surface of the filter paper belt 132 under the carrying of water, and then flows downward through the filter paper belt 132 under the suction action of the centrifugal pump 14, and the heavy suspended matter (which cannot float in water) is intercepted by the filter paper belt 132, and the effluent filtered by the filter paper belt 132 enters the water outlet zone. Finally, the filtered effluent is extracted through the water outlet 112 by the centrifugal pump 14. The oily wastewater completes two working processes in the sedimentation filter: sedimentation (floatation) separation and paper tape filtration. The light viscous suspended solids and heavy viscous suspended solids contained therein are effectively removed, making the SDI of the effluent water quality ≤5, creating good conditions for the subsequent fine treatment process.

During the filtration process of the filter paper belt 132, as the amount of sewage passing through increases, the filter paper belt 132 is gradually blocked, resulting in a decrease in the vacuum degree of the water outlet area. When the vacuum degree drops to a set value, an instruction is issued to the filter paper belt paper feeding mechanism 133, and the filter paper belt paper feeding mechanism 133 automatically feeds the paper, drags the new filter paper belt into the filter water tank 11, and sends the contaminated filter paper belt 132 to the waste paper storage box 134, thereby replacing the filter paper belt 132 and entering the next working cycle. This design does not require shutdown during the replacement of the filter paper belt.

The beneficial effects of this embodiment are:

1) By using the principle of sedimentation and buoyancy, the light viscous suspended matter is first separated from the influent water, which not only effectively recovers the floating oil (qualified crude oil), but also reduces the workload of the paper tape filtration, thereby extending the service life of the filter paper tape and reducing the amount of secondary oily waste generated; compared with the technical solution disclosed in the comparative document (CN216259472U), as shown in Figure 1, the existing buffer filter device does not have the separation function of light viscous suspended matter, and the light suspended matter causes serious contamination and blockage to the filter paper tape, which not only shortens the service life of the filter paper tape, but also increases the amount of secondary oily waste generated (the light viscous suspended matter is originally qualified crude oil that can be recovered, and it becomes secondary oily waste when it is contaminated on the filter paper tape). Compared with the existing buffer filter device, the technical solution of this embodiment extends the service life of the filter paper tape by more than two times, and reduces the amount of secondary oily waste generated by 60%.

2) The use of two floating oil baffles effectively prevents floating oil from contaminating the filter paper belt, further reducing the amount of secondary oily waste generated;

3) The combination of shallow pool sedimentation (natural sedimentation) and paper tape filtration (forced sedimentation) improves the working efficiency and treatment effect of oily wastewater treatment. After floating separation and paper tape filtration, the viscous suspended solids contained in the oily wastewater are effectively removed, and the SDI of the effluent water quality is ≤5, creating good conditions for the subsequent fine treatment process.

Example 3

As shown in FIG. 4 and FIG. 13 , this embodiment provides a high-efficiency oily wastewater filtering coalescer, comprising a filtering coalescing filter element group 22 , a housing 21 and an end cover 23 . Among them:

As shown in Fig. 4, in this embodiment, the filter coalescing filter element group 22 includes a plurality of filter coalescing filter elements 221. The design surface flow rate of the filter coalescing filter element 221 is 0.001 m/s, and the total filter area and the number of filter elements required for the filter separator 221 are calculated and determined based on the design flow rate. The filter coalescing filter element 221 uses a filter element with low flow resistance and large dirt holding capacity, with an initial pressure difference of ≤2KPa, an allowable working pressure difference of ≤60KPa, and a dirt holding capacity of ≥5200g/(L/min).

The filter coalescing filter element 221 is located in the filter element installation section 211; the filter coalescing filter element 221 includes a free end and an installation end (water inlet), the free end of the filter coalescing filter element 221 is sealed, and the free end of the filter coalescing filter element 221 faces the end cover direction of the housing; the installation end (water inlet) of the filter coalescing filter element 221 is sealed and connected to the filter element installation seat 21214. In the actual working process, sewage enters the interior of the coalescing filter element 221 through the filter element installation end (water inlet);

Specifically, as shown in FIG. 13 , the filter-coalescing filter element 221 flows from the inside to the outside. Inside the filter-coalescing filter element 221, sewage flows from the installation end (water inlet) of each filter-coalescing filter element 221 to the free end of the filter-coalescing filter element 221 (flowing from right to left), and at the same time, flows through the filter-coalescing filter element 221 from the inside to the outside. In this process, fine solid suspended matter is intercepted inside the filter-coalescing filter element 221, while fine liquid suspended matter (emulsified oil) is aggregated and grown on the outer surface of the filter-coalescing filter element 221 to form oil droplets with larger particle sizes. The aggregated and grown oil droplets flow out from the outside of the filter-coalescing filter element 221 and enter the filter element installation section. Since the flow rate (lateral and longitudinal) on the outer surface of the filter-coalescing filter element is relatively small, it is conducive to the aggregation and growth of the oil droplets after aggregation, creating favorable conditions for the subsequent floating separation.

In this example, the surface velocity of the filter coalescing filter element is 0.001 m/s, which is 20% of the prior art (in the prior art solution, the design surface velocity of the filter coalescing filter element is usually 0.005 m/s). The significant reduction in the design surface velocity will produce the following technical effects:

(1) Reduce the operating pressure difference of the filter coalescing filter element, thereby reducing the operating energy consumption of the equipment: The surface flow velocity of the filter coalescing filter element is proportional to its operating pressure difference, and the operating pressure difference of the equipment (mainly the pressure difference of the filter coalescing filter element) is proportional to the operating energy consumption. A significant reduction in the surface flow velocity of the filter coalescing filter element will inevitably significantly reduce the operating pressure difference of the equipment, thereby significantly reducing the operating energy consumption of the equipment.

(2) The number of filter coalescing filter elements 221 increases five times, thereby greatly increasing the pollution-absorbing capacity of the filter coalescer: when the working flow of the filter coalescer is constant, a decrease in the surface velocity of the filter coalescing filter element means an increase in the total surface area of the filter element, that is, an increase in the number of filter elements (when the outer dimensions of the filter elements are the same). If the surface velocity of the filter element decreases by 20%, the number of filter elements increases five times; when the pollution-absorbing capacity of a single filter coalescing filter element is constant, the number of filter elements increases five times, and the pollution-absorbing capacity of the filter coalescer will increase by more than five times.

(3) Improve the coalescing effect of the filter coalescing element. The lower the surface velocity, the better the coalescing effect (the larger the particle size of the oil droplets after coalescing). The larger the particle size of the oil droplets after coalescing, the better the floating separation effect. This will help improve the oil removal effect of the filter coalescer.

As shown in Figures 11 and 12, the filtering and coalescing filter element 221 in this embodiment includes a filtering combination layer 2211, a skeleton 2212 and a coalescing combination layer 2213 which are arranged in sequence. The filtering combination layer 2211 is folded and arranged on the inner side of the skeleton 2212, and the coalescing combination layer 2213 is wound and arranged on the outer side of the skeleton 2212 in sequence.

As shown in Figure 14, the filtration layer area of a traditional filtration coalescing filter element (flowing from outside to inside) is its outer surface area (circumference x length), while the filtration combination layer 223211 in this embodiment is a folded structure, and its filtration area is the expanded area (number of folds x 2 x fold height x length). When the filter element length and outer diameter are the same, the filtration area (expanded area) of the filtration combination layer 223211 in this embodiment is 4 times that of a traditional filtration coalescing filter element (cylindrical structure), and its apparent dirt holding capacity will be increased by 5-9 times.

The dirt-holding capacity of a filter element is directly proportional to its filtration area (index) and inversely proportional to the filtration speed (index). In this embodiment, the filtration area (expanded area) of a single filter-coalescing filter element is increased by 4 times. Under the same processing flow rate, the number of filter elements is increased by 5 times (the surface flow rate is reduced by 20%). These two technical measures work together (there may be a superposition effect), so that the dirt-holding capacity of the filter-coalescing filter element reaches 5200g/(L/min).

In this embodiment, the apparent dirt holding capacity of the filtering coalescing filter element is 5200g/(L/min), and the replacement cycle of the filter element is 12 months. For a device with a working flow of ^180m3 /h, the cost of replacing the filter element once is 231,500 yuan (including: the purchase cost of the filter element is 211,500 yuan, and the replacement cost is 20,000 yuan), and the annual filter element replacement cost is 231,500 yuan after conversion; while in the prior art, the apparent dirt holding capacity of the filtering coalescing filter element is 420g/(L/min), and the replacement cycle of the filter element is 1 month. For a device with a working flow of ^180m3 /h, the cost of replacing the filter element once is 42,300 yuan (including: the purchase cost of the filter element is 24,300 yuan, and the replacement cost is 18,000 yuan), and the annual filter element replacement cost is 507,600 yuan after conversion; compared with the prior art solution, the annual filter element replacement cost of this embodiment saves 54.4%.

As shown in FIG. 4 , in this embodiment, the housing 21 is formed by welding a filter element installation section 211 , a water inlet distribution section 212 , and a floating separation section 213 in sequence.

As shown in Figures 7, 8 and 9, in this embodiment, a water inlet distribution cavity 2121 is provided at the upper part of the water inlet distribution section 212, and a crescent-shaped flow channel is provided at the lower part. A crescent-shaped flow channel 2122 is left at the lower part of the water inlet distribution section 212, and the flow channel 2122 connects the filter element installation section 211 and the floating separation section 213.

As shown in Figures 4, 7, 8, 9 and 10, in a feasible implementation scheme, the water inlet distribution cavity 2121 in this embodiment is composed of a mounting tube sheet 21211, a vertical partition 21212, a horizontal partition 21213 and an outer cylinder, and a plurality of filter element mounting seats 21214 are provided on the mounting tube sheet 21211. The filter coalescing filter element 221 is installed on the filter element mounting seat 21214, and each filter element mounting seat 21214 is provided with an internal flow channel, which connects the water inlet distribution cavity 2121 with the interior of the filter coalescing filter element 221.

In this embodiment, the coalesced and grown oil droplets flowing out from the outer surface of the filter coalescing filter element 221 enter the inner cavity of the cylinder of the filter element mounting section 211; in the inner cavity of the cylinder of the filter element mounting section 211, the coalesced water flow flows from left to right, and at the same time, the coalesced and grown oil droplets float upward due to their own buoyancy. Since a crescent-shaped flow channel 2122 is provided on the upper part of the cylinder of the water inlet distribution section 212, the coalesced water flow also flows from bottom to top, and the flow direction of the water flow is consistent with the floating direction of the oil droplets, thereby improving the floating separation effect.

In this embodiment, the oil droplets that fail to float and separate in the filter element installation section 211 are carried by the water flow through the crescent-shaped flow channel 2122 at the upper part of the water inlet distribution cavity 2121 and enter the inner cavity of the cylinder of the floating separation section 213 .

In this embodiment, water flows into the inner cavity of the cylinder of the buoyancy separation section 213 from the top and then continues to flow from left to right; in this process, due to the difference in specific gravity of oil and water, water sinks downward while oil droplets float upward, achieving a second buoyancy separation.

In this embodiment, the oil droplets after buoyancy separation are collected into the oil collecting bag 216 and discharged from the oil discharge port. At the same time, the water flow after buoyancy separation flows to the right side of the buoyancy separation section 213 and flows out through the water outlet 215 to obtain clean outlet water.

As shown in Figure 4, in a feasible implementation scheme, the shell 21 in this embodiment also includes a water inlet 214, a water outlet 215 and an oil collecting bag 216. The water inlet 214 is connected to the inside of the water inlet distribution cavity 2121, the water outlet 215 is arranged on the side of the buoyancy separation section 213 away from the filter element installation section 211, and the oil collecting bag 216 is arranged on the upper right side of the buoyancy separation section 213.

As shown in FIG. 5 and FIG. 6 , in a feasible implementation scheme, a separation element that blocks oil and allows water to pass may be provided in the floating separation section 213 of this embodiment, and the separation element includes a blade separator 2131 or a separation filter element 2132 .

Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims (9)

1. A high-efficiency integrated treatment system for oilfield produced water, characterized by: comprising an oily wastewater sedimentation filter and an oily wastewater filtration coalescer connected in sequence: The oily wastewater sedimentation filter comprises a filter water tank, a sedimentation separation mechanism and a paper tape filter mechanism, wherein the sedimentation separation mechanism is arranged in the upper area of the filter water tank, and the paper tape filter mechanism is installed on the filter water tank; The sedimentation separation mechanism includes a sedimentation/floating separation area, an oil floating baffle and an oil skimming mechanism. The inner cavity of the filtered water tank is provided with a water inlet area and a water outlet area. The oil floating baffle is arranged in the water inlet area. The oil floating baffle includes a left baffle and a right baffle. The area between the two oil floating baffles is the sedimentation/floating separation area. The oil skimming mechanism is installed above the sedimentation/floating separation area. The oily wastewater filtration coalescer comprises a filtration coalescing filter element group, a shell and an end cover: The filter coalescing filter element group comprises a plurality of filter coalescing filter elements, and the designed surface flow rate thereof is ≤0.001m/s; the initial pressure difference of the filter coalescing filter element is ≤2Kpa, and the allowable working pressure difference is ≤60KPa; the apparent dirt holding capacity of the filter coalescing filter element is ≥5200g/(L/min); The housing comprises a filter element installation section, a water inlet flow distribution section and a floating separation section, wherein the lower part of the inner cavity of the water inlet flow distribution section is provided with a water inlet flow distribution cavity, and the upper part is provided with a crescent-shaped flow channel, and the crescent-shaped flow channel connects the filter element installation section and the floating separation section; The filtering and coalescing filter element group is installed in the filter element installation section of the housing. 2. According to claim 1, a high-efficiency integrated treatment system for oilfield produced water is characterized in that: the filtered water tank is a rectangular structure, with a paper inlet on the upper left side and a paper outlet on the upper right side; a first water inlet and a first water outlet are provided at appropriate positions of the filtered water tank. 3. A high-energy-efficiency integrated treatment system for oilfield produced water according to claim 1, characterized in that: the paper tape filtering mechanism includes a filter paper tape roll, a filter paper tape, a filter paper tape paper removal mechanism and a waste paper storage box, and the filter paper tape roll and the waste paper storage box are installed on the outside of the filter water tank; the filter paper tape enters the filter water tank from the paper inlet, horizontally penetrates the filter water tank, and then leaves the filter water tank from the paper outlet; the filter paper tape divides the inner cavity of the filter water tank into two parts: the area above the filter paper tape is the water inlet area, and the area below the filter paper tape is the water outlet area; the water inlet area is provided with a first water inlet, and the water outlet area is provided with a first water outlet. 4. A high-efficiency integrated treatment system for oilfield produced water according to claim 1, characterized in that: a first water inlet is provided at the lower inner side of the left partition of the sedimentation/floatation separation zone, the first water inlet is arranged horizontally, and is connected to the sedimentation/floatation separation zone; the first water inlet is arranged above the filter paper belt, and the oil skimming mechanism is installed at the upper inner side of the right partition of the sedimentation/floatation separation zone, for extracting floating oil from the sedimentation/floatation separation zone; the oil skimming mechanism is located away from the first water inlet. 5. According to claim 1, a high-efficiency integrated treatment system for oilfield produced water is characterized in that: the filtering and coalescing filter element comprises a filtering combination layer, a skeleton and a coalescing combination layer arranged in sequence, the filtering combination layer is folded and arranged on the inner side of the skeleton, and the coalescing combination layer is wound and arranged on the outer side of the skeleton; the unfolded area of the folded filtering combination layer is more than 3 times the outer surface area of the filtering and coalescing filter element. 6. A high-efficiency integrated treatment system for oilfield produced water according to claim 1, characterized in that: the water inlet distribution cavity is composed of a mounting tube sheet, a vertical partition, a horizontal partition and an outer cylinder, the mounting tube sheet is provided with a plurality of filter element mounting seats, each filter element mounting seat is provided with an internal flow channel, connecting the water inlet distribution cavity with the interior of the filter coalescing filter element; a second water inlet is provided on the outer cylinder, and the second water inlet is connected to the interior of the water inlet distribution cavity. 7. According to claim 1, a high-efficiency integrated treatment system for oilfield produced water is characterized in that: the filtering and coalescing filter element is located in the filter element installation section, the filtering and coalescing filter element includes a free end and a mounting end, the free end of the filtering and coalescing filter element is sealed, the free end of the filtering and coalescing filter element is facing the end cover direction of the shell, the mounting end of the filtering and coalescing filter element is sealed and connected to the filter element mounting seat, and its interior is connected to the water inlet distribution cavity. 8. According to claim 1, a high-efficiency integrated treatment system for oilfield produced water is characterized in that: the shell also includes a second water inlet, a second water outlet and an oil collecting bag, the second water inlet is connected to the inside of the water inlet distribution cavity, the second water inlet is arranged on the water inlet distribution section, the second water outlet is arranged at the lower right of the floating separation section, the oil collecting bag is arranged at the upper right of the floating separation section, the second water outlet and the oil collecting bag are both connected to the inner cavity of the floating separation section; the second water outlet is far away from the oil collecting bag. 9. A high-energy-efficiency integrated treatment system for oilfield produced water according to claim 2, characterized in that: the oily wastewater sedimentation filter also includes a centrifugal pump, and the centrifugal pump is connected to the first water outlet through a pipeline.