Petroleum production wastewater treatment and recycling device

Abstract

The invention provides a petroleum production wastewater treatment and recycling device which is characterized in that a floating oil cleaning mechanism is arranged on an oil separation tank and comprises a low-temperature roller, at least part of the low-temperature roller is immersed into wastewater in the oil separation tank, and the floating oil can be removed through the low-temperature state of the outer surface of the low-temperature roller; heavy floating oil with the condensation temperature of 20-40 DEG C on the surface of the wastewater is solidified and attached to the low-temperature roller, meanwhile, water is prevented from being brought out due to solidification, and then solidified oil attached to the outer surface of the low-temperature roller is scraped and collected through a scraper. On the basis of the components of the floating oil, the floating oil can be highly selectively solidified and attached to the low-temperature roller by controlling the temperature of the outer surface of the low-temperature roller, so that the water content in the separated floating oil is effectively reduced, the cost of further oil-water separation of the subsequent floating oil is reduced, and the treatment efficiency of the oil production wastewater is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil extraction wastewater treatment, and particularly relates to a device for treating and recycling oil extraction wastewater. BACKGROUND

[0002] Oil extraction wastewater (also known as "produced water") is oil-containing wastewater generated in the process of oil field exploitation, and mainly comes from water separated from produced liquid of an oil extraction well, well washing wastewater, drilling wastewater and flushing water of a gathering and transportation system. The oil extraction wastewater has the characteristics of complex composition (containing crude oil, suspended solids, inorganic salts, heavy metals, organic matters such as phenols / sulfides / polymers, etc.), high emulsification degree (small oil droplet size, mostly 0.1-10 microns of stable emulsion) and large water quality fluctuation (changes with the exploitation stage), and needs to be treated by a multi-stage treatment process to achieve standard discharge or recycling. The existing oil extraction wastewater treatment process is: oil separation (scraping off heavy floating oil such as heavy fuel oil and crude oil on the surface) -> coagulation air flotation (separating light oil emulsified in water) -> A / O biological denitrification -> filtration -> disinfection.

[0003] In the first oil separation process in the existing treatment process, the floating oil on the liquid surface is scraped off by an oil scraper. However, under the agitation of the oil scraper, the heavy floating oil is easy to form an oil-water mixture, and a large amount of wastewater is taken away, so that a large amount of wastewater is mixed in the scraped floating oil, greatly increasing the cost of further oil-water separation of the floating oil. SUMMARY

[0004] Therefore, the present application aims to provide a device for treating and recycling oil extraction wastewater, so as to solve the problem that the floating oil separated by the existing oil extraction wastewater treatment process has a large amount of wastewater, greatly increasing the cost of further oil-water separation of the floating oil.

[0005] The present application provides a device for treating and recycling oil extraction wastewater, which comprises: sequentially connected oil separation tanks, air flotation tanks, filtration tanks and disinfection tanks, and a floating oil cleaning mechanism is arranged on the oil separation tank, wherein the floating oil cleaning mechanism comprises: a low-temperature roller, which is at least partially immersed in the wastewater in the oil separation tank, and is used to make the floating oil on the surface of the wastewater solidify and adhere to the low-temperature roller by the low-temperature state of the outer surface of the low-temperature roller; a scraper, which is used to scrape off the solidified oil adhered to the outer surface of the low-temperature roller, and the oil scraping surface of the scraper comprises an oil-repellent layer.

[0006] Optionally, the low-temperature roller comprises a semiconductor refrigeration layer, and outer and inner heat-conducting layers clamping the semiconductor refrigeration layer; Both ends of the low-temperature roller are sealingly connected with heat dissipation pipelines for heat dissipation of the inner heat-conducting layer.

[0007] Optionally, the internal space of the low-temperature drum is led out through connecting pipes at both ends. A first bearing is provided outside the connecting pipe and is rotatably connected to the mounting frame through the first bearing. The mounting frame is fixedly connected to the oil separator. A sealed bearing is also installed inside the connecting pipe, and the pipe is connected to the heat dissipation pipe through the sealed bearing.

[0008] Optionally, the heat dissipation pipe is also connected to the air supply pipe of the flotation tank, for heating the water in the flotation tank according to the hot air discharged from the heat dissipation pipe.

[0009] Optionally, the oil slick cleaning mechanism further includes: A guide frame is fixedly mounted on the oil separator. The extension direction of the guide frame is consistent with the rolling direction of the low-temperature drum and parallel to the outer surface of the low-temperature drum. The scraper is slidably mounted on the guide frame. A collection box is fixedly installed on the oil separator, and the scraper's discharge side extends into the collection box; A vibration actuator is fixedly mounted on the oil separator, and the vibration end of the vibration actuator is connected to the scraper drive.

[0010] Optionally, a first spring is also fitted on the guide frame, and the lower surface of the scraper is elastically connected to the guide frame through the first spring. The vibration driver is disposed above the scraper, and the vibration end of the vibration driver abuts against the upper surface of the scraper.

[0011] Optionally, the inner surface of the cryogenic roller is further provided with turbulence vanes.

[0012] The oilfield wastewater treatment and recycling device provided by this invention includes an oil spill cleaning mechanism on an oil separator. This mechanism comprises a low-temperature drum, which is at least partially immersed in the wastewater in the oil separator. The low temperature of the drum's outer surface causes heavy oil (with a condensation temperature between 20°C and 40°C) to solidify and adhere to the drum, while preventing the solidified water from being carried away. The solidified oil is then scraped off and collected by a scraper. Based on the composition of the oil spill, this invention, by controlling the outer surface temperature of the low-temperature drum, can selectively solidify and adhere the oil to the drum, effectively reducing the water content in the separated oil, lowering the cost of further oil-water separation, and improving the treatment efficiency of oilfield wastewater. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall modular structure of the oilfield wastewater treatment and recycling device in an embodiment of the present invention from a first-view perspective. Figure 2This is a schematic diagram of the overall modular structure of the oilfield wastewater treatment and recycling device in an embodiment of the present invention from a second perspective. Figure 3 This is a schematic diagram showing the installation position of the floating oil cleaning mechanism in the oilfield wastewater treatment and recycling device according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the external structure of the floating oil cleaning mechanism of the oilfield wastewater treatment and recycling device in an embodiment of the present invention. Figure 5 This is a partial cross-sectional view of the oil spill cleaning mechanism of the oilfield wastewater treatment and recycling device in an embodiment of the present invention. Figure 6 This is a schematic diagram of the pipeline installation of the floating oil cleaning mechanism in the oilfield wastewater treatment and recycling device according to an embodiment of the present invention. Figure 7 for Figure 6 A magnified view of a portion of region A in the middle; Figure 8 This is a schematic diagram of the scraper section of the floating oil cleaning mechanism in the oilfield wastewater treatment and recycling device according to an embodiment of the present invention. Figure 9 This is a schematic diagram of the main structure of the filter pool in the oilfield wastewater treatment and recycling device of the present invention. Figure 10 for Figure 9 A magnified view of a portion of region B in the middle.

[0014] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0015] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0016] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0018] To address the problem that existing oilfield wastewater treatment processes often separate oil containing large amounts of wastewater, significantly increasing the cost of subsequent oil-water separation, this invention provides an oilfield wastewater treatment and recycling device. This device includes an oil spill cleaning mechanism on an oil separator. The mechanism comprises a low-temperature drum, which is at least partially immersed in the wastewater in the oil separator. The low temperature (e.g., 10°C) on the outer surface of the drum causes heavy oil with a condensation temperature between 20°C and 40°C to solidify and adhere to the drum, while preventing the solidified water from being carried away. The solidified oil is then scraped off and collected by a scraper. This highly selective method effectively reduces the water content in the separated oil, lowers the cost of subsequent oil-water separation, and improves the treatment efficiency of oilfield wastewater.

[0019] Specifically, such as Figure 1 and Figure 2 As shown, the oilfield wastewater treatment and recycling device of this embodiment includes an oil separator 102, an air flotation tank 103, a filter tank 104, and a disinfection tank 105 connected in sequence. Each treatment tank is enclosed and separated by a base 100 (made of reinforced concrete, stainless steel, etc.). The treatment tanks can be arranged continuously or separately, with wastewater transported through closed pipes or semi-open ditches (not shown in the figure). The specific arrangement can be selected according to actual needs, and this application does not impose any particular limitations on this.

[0020] The front end of the oil separator 102 is equipped with an equipment compartment 101 for housing hardware equipment such as drives, main controllers, and monitoring systems.

[0021] Oil separator 102 is used for cleaning floating oil in wastewater. The floating oil is mainly heavy oil, with a melting point typically between 20°C and 40°C. Therefore, in this embodiment, as... Figure 3 , Figure 4 and Figure 5As shown, an oil-water separation mechanism 200 is provided on the base 100 of the oil separator 102. The oil-water separation mechanism 200 includes a low-temperature roller 202 and a scraper 208. The height of the low-temperature roller 202 is related to the wastewater level in the oil separator 102 and is set according to the actual situation. The low-temperature roller 202 needs to be at least partially immersed in the wastewater in the oil separator 102 so that the floating oil on the surface of the oil separator 102 can come into contact with the low-temperature roller 202. Through the low temperature state of the outer surface of the low-temperature roller 202, the floating oil on the surface of the wastewater solidifies and adheres to the low-temperature roller 202. Then, the scraper 208 scrapes off the solidified oil adhering to the outer surface of the low-temperature roller 202.

[0022] To prevent oil from adhering to the scraper 208, the scraping surface of the scraper 208 (the upper surface in this embodiment) includes an oleophobic layer, so that the scraped solidified oil can fall along the inclined surface of the scraper 208 into the collection box 207 (which also has an oleophobic layer for cleaning and unloading). The oleophobic layer can be, for example, a fluorosilicone rubber coating, a superhydrophobic / oleophobic nano-coating, or a polydimethylsiloxane coating, etc., and can be specifically selected according to actual needs.

[0023] In this embodiment, the scraper 208 is inclined, with its side away from the cryogenic drum 202 tilting downwards, so that the scraped solidified oil can fall into the collection box 207 located at the bottom of the scraper 208 (the scraper 208 has a short discharge stroke). The collection box 207 can also be inclined along the axial direction of the cryogenic drum 202, with its lower end extending to the oil separator 102 and having a discharge port to discharge the collected solidified oil to an external collection module (such as an oil drum), from which it is transferred to subsequent oil treatment equipment. In an optional embodiment, the scraper 208 can be inclined along the axial direction of the cryogenic drum 202, forming a spiral arrangement around the outer surface of the cryogenic drum 202, which can directly transport the scraped solidified oil to the external collection module.

[0024] A mounting frame 203 is fixedly installed on the base 100 of the oil separator 102. The floating oil cleaning mechanism 200 is mainly fixed to the oil separator 102 via the mounting frame 203. A drive assembly 204 is installed at one end to drive the low-temperature drum 202 to rotate. A connecting plate 205 is fixed in the middle of the mounting frame 203. The two ends of the low-temperature drum 202 are rotatably connected to the connecting plate 205 via first bearings 206, so that the low-temperature drum 202 is centered relative to the mounting frame 203, improving stability. The scraper 208 and the collection box 207 are fixed to the mounting frame 203.

[0025] The drive assembly 204 includes a drive motor 2041, a first bevel gear 2042, and a second bevel gear 2043. The drive motor 2041 is fixed on the mounting bracket 203, and the second bevel gear 2043 is fixed on the output shaft of the drive motor 2041. The first bevel gear 2042 is coaxially and fixedly connected to the cryogenic drum 202, and the first bevel gear 2042 and the second bevel gear 2043 are meshed together. The drive motor 2041 drives the cryogenic drum 202 to rotate.

[0026] The scraper 208 is positioned according to the rolling direction of the low-temperature drum 202. When the movement direction of the lower surface of the low-temperature drum 202 is the same as the wastewater flow direction, the scraper 208 is positioned on the upstream side of the wastewater flow; otherwise, it is positioned on the downstream side of the wastewater flow. The direction of movement of the lower surface of the low-temperature drum 202 in the same or opposite direction to the wastewater flow direction can be selected based on the actual differences in treatment efficiency, and this application does not impose any special limitations on this.

[0027] To facilitate cooling, semiconductor cooling is selected in this embodiment to meet the cooling requirements. Specifically, the low-temperature roller 202 includes a semiconductor cooling layer 2021, and an outer heat-conducting layer 2022 and an inner heat-conducting layer 2023 that hold the semiconductor cooling layer 2021, such as... Figure 6 As shown, the low-temperature roller 202 is sealed at both ends with heat dissipation pipes, including an air inlet pipe 2014 and an air outlet pipe 2015, for heat dissipation of the inner heat-conducting layer 2023, to ensure the temperature difference between the inside and outside, thereby ensuring the low-temperature state of the outer heat-conducting layer 2022 and ensuring reliability.

[0028] Please refer to further details. Figure 7 The internal space of the low-temperature drum 202 is led out through the connecting pipes 2025 at both ends. A first bearing 2026 is provided outside the connecting pipe 2025 and is rotatably connected to the connecting plate 205 through the first bearing 2026. A sealed bearing 2027 is also provided inside the connecting pipe 2025 and is connected to the heat dissipation pipe through the sealed bearing 2027 to ensure the unidirectional flow of heat dissipation air and ensure heat dissipation efficiency.

[0029] To improve heat dissipation efficiency, a baffle 2024 is also provided on the inner surface of the cryogenic drum 202. The baffle 2024 extends radially from the outside to the inside of the cryogenic drum 202, adopting a shaftless mode to increase throughput. The baffle 2024 can diffuse the airflow entering through the smaller inner diameter connecting pipe 2025 to the entire space inside the larger inner diameter cryogenic drum 202, improving the heat exchange effect between the heat dissipation airflow and the inner wall of the cryogenic drum 202.

[0030] The thermoelectric cooling layer 2021 requires direct power supply. Its power supply cable 20211 can be embedded inside the cryogenic roller 202. The connecting pipes 2025 at both ends of the cryogenic roller 202 are extended, and the power supply cable 20211 is guided to the outside of the oil separator 102 through the connecting pipes 2025. An electric slip ring is installed on the connecting pipe 2025 to supply power to the rotating cryogenic roller 202. This avoids the influence of liquid in the oil separator on the power supply cable 20211, ensuring the reliability of the power supply to the thermoelectric cooling layer 2021. The connecting pipe 2025 bears the weight of the cryogenic roller 202 and is generally quite thick. It has mounting slots for the power supply cable 20211 and generally also ensures its support reliability. Specific parameters can be designed according to actual conditions to ensure mechanical and electrical reliability.

[0031] To further reduce the amount of solidified oil remaining on the scraper 208 and thus improve the efficiency of oil removal, in this embodiment, please refer to... Figure 4 and Figure 8 The oil spill cleaning mechanism 200 also includes a material feeding auxiliary module 206. The material feeding auxiliary module 206 is located at both ends of the scraper 208 and includes a mounting frame 2061, a slider 2062, a guide frame 2063, a vibration driver 2064, and a first spring 2065. The mounting frame 2061 is fixed on the mounting frame 203. The guide frame 2063 and the vibration driver 2064 are fixedly mounted on the mounting frame 2061. The slider 2062 is loosely fitted on the guide frame 2063 and is fixedly connected to the scraper 208 so that the scraper 208 can slide along the guide frame 2063 through the slider 2062.

[0032] The extension direction of the guide frame 2063 is consistent with the rolling direction of the cryogenic roller 202 and parallel to the outer surface of the cryogenic roller 202, so that the scraper 208 maintains contact with the outer surface of the cryogenic roller 202 during the movement, ensuring the reliability of scraping solidified oil on the cryogenic roller 202.

[0033] The vibration end of the vibration driver 2064 is connected to the scraper 208 for transmission. When working, it can drive the scraper 208 to vibrate so that the solidified oil on the scraper 208 can vibrate and be discharged.

[0034] In this embodiment, the first spring 2065 is sleeved on the guide frame 2063, and the lower surface of the scraper 208 is elastically connected to the guide frame 2063 through the first spring 2065. The vibration driver 2064 is disposed above the scraper 208, and the vibration end of the vibration driver 2064 abuts against the upper surface of the scraper 208. The vibration driver 2064 drives the scraper 208 to move downward. When the vibration driver 2064 retracts, the first spring 2065 drives the scraper 208 to move upward and reset. Overall, the scraper 208 is not fixedly connected, which can avoid system jamming and damage when sliding on the guide frame 2063 is obstructed.

[0035] To improve system energy utilization, in this embodiment, the heat dissipation pipe is also connected to the air supply pipe 2012 of the flotation tank 103, for heating the water in the flotation tank 103 based on the hot air discharged from the heat dissipation pipe. Specifically, as shown... Figure 6 As shown, in the gas supply module 201, the gas supply pipe 2012 connects the air pump 2011 and the flotation pipe 2013 laid at the bottom of the flotation tank 103 to provide gas to the flotation tank 103.

[0036] The input end of the air inlet pipe 2014 and the first output end of the air outlet pipe 2015 are respectively connected to the upstream node and the downstream node of the air supply pipe 2012. A first control valve is also provided between the upstream node and the downstream node of the air supply pipe 2012. The second output end of the air outlet pipe 2015 discharges directly (not shown in the figure). The two output ends of the air outlet pipe 2015 are respectively provided with a second control valve and a third control valve to control the air outlet direction of the air outlet pipe 2015.

[0037] The host computer (not shown in the figure) also detects the temperature of the flotation tank 103. When heating is required, it controls the first control valve to close, the second control valve to close, and the third control valve to open. Then, the output gas of the air pump 2011 is transmitted to the flotation pipe 2013 through the downstream node of the inlet pipe 2014, the low temperature drum 202, the outlet pipe 2015, and the supply pipe 2012. The airflow heated by the low temperature drum 202 is provided to the flotation tank 103. The high temperature side energy in the semiconductor refrigeration is used to heat the flotation tank 103, thereby promoting the oil-water separation efficiency in the flotation tank 103 and improving the energy utilization efficiency.

[0038] To improve filtration efficiency, such as Figure 9 and Figure 10 As shown, in this embodiment, a self-cleaning filter module 300 is provided in the filter tank 104. A fixed plate 302 parallel to the filter plate 1041 is provided in the filter tank 104. An impact block 301 is provided on the fixed plate 302. When the fixed plate 302 is driven to reciprocate close to the filter plate 1041, the impact block 301 periodically knocks on the filter plate 1041, which can shake and remove solid debris attached to the filter plate 1041, and prevent the filter plate 1041 from being blocked.

[0039] The filter plate 1041 is fixed in the filter tank 104, and the fixing bracket 303 is fixed on the filter plate 1041 for the installation of the rotary motor 304 and the guide rod 306. The fixing plate 302 is slidably disposed on the second guide rod 306. The second guide rod 306 is loosely fitted with a second spring 307, which is clamped between the filter plate 1041 and the fixing plate 302. The rotating end of the rotary motor 304 is fixedly provided with a cam 305. The rotation of the cam 305 drives the fixing plate 302 to move periodically along the second guide rod 306, thereby controlling the impact block 301 on the fixing plate 302 to periodically strike the filter plate 1041.

[0040] In this embodiment, the filter plates 1041 are arranged in pairs, and the fixed plates 302 are also arranged in pairs with the two filter plates 1041. The cam 305 is a double-headed cam, which drives the two fixed plates 302 to move symmetrically and synchronously.

[0041] The oilfield wastewater treatment and recycling device provided by this invention has an oil spill cleaning mechanism on the oil separator. The oil spill cleaning mechanism includes a low-temperature drum. The low-temperature drum is at least partially immersed in the wastewater in the oil separator. The low temperature of the outer surface of the low-temperature drum, such as 10°C, causes the heavy oil with a condensation temperature of 20°C to 40°C on the surface of the wastewater to solidify and adhere to the low-temperature drum. At the same time, it prevents the solidified water from being carried out. The solidified oil adhering to the outer surface of the low-temperature drum is then scraped off and collected by a scraper. This device can selectively solidify and adhere the oil to the low-temperature drum, effectively reducing the water content in the separated oil, reducing the cost of further oil-water separation, and improving the treatment efficiency of oilfield wastewater.

[0042] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0043] The above-described embodiments are merely illustrative of several specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of protection of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A device for treating and recycling oilfield wastewater, characterized in that, include: The system comprises a sequentially connected oil separator, flotation tank, filtration tank, and disinfection tank. The oil separator is equipped with an oil flotation cleaning mechanism, which includes: A low-temperature drum, which is at least partially immersed in the wastewater in the oil separator, is used to cause the floating oil on the surface of the wastewater to solidify and adhere to the low-temperature drum through the low-temperature state of the outer surface of the drum. A scraper is used to scrape off the solidified oil adhering to the outer surface of the low-temperature drum, and the scraping surface of the scraper includes an oleophobic layer.

2. The oilfield wastewater treatment and recycling device according to claim 1, characterized in that, The low-temperature roller includes a semiconductor cooling layer, and an outer heat-conducting layer and an inner heat-conducting layer that hold the semiconductor cooling layer. The low-temperature roller is sealed at both ends with heat dissipation pipes for heat dissipation of the inner heat-conducting layer.

3. The oilfield wastewater treatment and recycling device according to claim 2, characterized in that, The internal space of the low-temperature drum is led out through connecting pipes at both ends. A first bearing is provided outside the connecting pipe and is rotatably connected to the mounting frame through the first bearing. The mounting frame is fixedly connected to the oil separator. A sealed bearing is also installed inside the connecting pipe, and the pipe is connected to the heat dissipation pipe through the sealed bearing.

4. The oilfield wastewater treatment and recycling device according to claim 2, characterized in that, The heat dissipation pipe is also connected to the air supply pipe of the flotation tank, and is used to heat the water in the flotation tank according to the hot air discharged from the heat dissipation pipe.

5. The oilfield wastewater treatment and recycling device according to claim 1, characterized in that, The oil spill cleaning mechanism also includes: A guide frame is fixedly mounted on the oil separator. The extension direction of the guide frame is consistent with the rolling direction of the low-temperature drum and parallel to the outer surface of the low-temperature drum. The scraper is slidably mounted on the guide frame. A collection box is fixedly installed on the oil separator, and the scraper's discharge side extends into the collection box; A vibration actuator is fixedly mounted on the oil separator, and the vibration end of the vibration actuator is connected to the scraper drive.

6. The oilfield wastewater treatment and recycling device according to claim 5, characterized in that, The guide frame is also fitted with a first spring, and the lower surface of the scraper is elastically connected to the guide frame through the first spring. The vibration driver is disposed above the scraper, and the vibration end of the vibration driver abuts against the upper surface of the scraper.

7. The oilfield wastewater treatment and recycling device according to claim 1, characterized in that, The inner surface of the low-temperature drum is also provided with turbulence vanes.

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