A VOCs balance tank system with pressure gradient design and an oil and gas treatment method

Abstract

The application provides a VOCs balance tank system with a pressure gradient design and an oil and gas treatment method, the VOCs balance tank system with the pressure gradient design comprises at least two storage tanks, any storage tank is provided with a tank top breather valve and an emergency pressure relief device, the exhaust pressure of the tank top breather valve is not less than 3.8 KPaG, and the relief pressure of the emergency pressure relief device is not less than 5.8 KPaG; the balance tank is in communication with a gas phase space of the storage tank through a gas phase balance pipe, a single call valve is arranged on the gas phase balance pipe, and the call-out pressure of the single call valve is greater than or equal to 2.8 KPaG; a gas phase discharge pipe is connected to the top of the balance tank, an on-off valve is arranged on the gas phase discharge pipe, the on-off valve is opened when the internal pressure of the balance tank is greater than or equal to 2.8 KPaG, and the gas phase discharge pipe delivers volatile organic compounds to a downstream treatment device. The application ensures that volatile organic compounds are collected in an orderly manner under normal fluctuations, avoids waste of raw materials and reduces production cost, and eliminates the fire, explosion and other safety risks caused by the air supply fan as a potential ignition source.

Description

Technical Field

[0001] This invention belongs to the field of VOCs treatment and oil and gas recovery technology, and relates to a VOCs balancing tank system with pressure gradient design and an oil and gas treatment method. Background Technology

[0002] Currently, the odorous gas emissions from the breathing of atmospheric oil storage tanks, the volatilization of residual oil, shutdown cleaning, and the volatilization of solvents carried in the oil are among the main sources of VOCs (volatile organic compounds) in the plant area.

[0003] Most current chemical oil storage tanks are atmospheric pressure tanks, designed with pressures of -0.49 / 2.0 kPaG. The typical pressure control scheme for these tanks is as follows: breather valve intake pressure P ≤ -0.3 kPaG, nitrogen sealing pressure 0.2~0.5 kPaG, single breather valve pressure P ≥ 0.9 kPaG, breather valve exhaust pressure P ≥ 1.35 kPaG, and emergency relief pressure P ≥ 1.8 kPaG. Under this pressure gradient, changes in material inflow / outflow and temperature can easily cause pressure fluctuations within the tank, leading to increased VOC emissions in the tank area. Large amounts of oil and gas are emitted into the exhaust gas treatment unit, resulting in raw material waste and increased production costs.

[0004] In addition, existing technologies often use oil and gas conveying fans to transport oil and gas, which cannot be energy-intensive, and the fans also pose a safety risk of fire and explosion as potential ignition sources. Summary of the Invention

[0005] This application provides a VOCs balance tank system with pressure gradient design and an oil and gas treatment method to solve the problems existing in the prior art, ensure the orderly collection of volatile organic compounds under normal fluctuations, avoid raw material waste and reduce production costs, and eliminate the safety risks such as fire and explosion caused by the blower as a potential ignition source.

[0006] The VOCs balancing tank system with pressure gradient design provided in this application includes: at least two storage tanks, each of which is equipped with a top-mounted breather valve and an emergency pressure relief device. The exhaust pressure of the top-mounted breather valve is not less than 3.8 kPaG, and the release pressure of the emergency pressure relief device is not less than 5.8 kPaG. A balancing tank is connected to the gas phase space of the at least two storage tanks via a gas phase balancing pipe for receiving and buffering volatile organic compounds from each of the storage tanks. A single-exhale valve is installed on the gas phase balancing pipe, and the exhale pressure of the single-exhale valve is greater than or equal to 2.8 kPaG. A gas phase discharge pipe is connected to the top of the balancing tank, and a switch valve is installed on the gas phase discharge pipe. When the internal pressure of the balancing tank is greater than or equal to 2.8 kPaG, the switch valve opens, and the gas phase discharge pipe transports the volatile organic compounds to a downstream treatment device.

[0007] Optionally, any of the storage tanks is further provided with a nitrogen sealing system, wherein: the nitrogen sealing system includes a nitrogen supply pipe connected to the gas phase space, the nitrogen supply pipe is opened when the pressure of the gas phase space is less than or equal to 0.2 kPaG, and the nitrogen supply pipe is closed when the pressure of the gas phase space is greater than or equal to 0.5 kPaG.

[0008] Optionally, a pressure transmitter is installed on the top of the balance tank; both the switching valve and the pressure transmitter are communicatively connected to the pressure controller. When the pressure transmitter detects that the pressure on the top of the balance tank is equal to or greater than 2.8 kPaG, the pressure controller controls the switching valve to open.

[0009] Optionally, the balance tank is equipped with a condenser coil, through which a cooling medium is circulated to cool the volatile organic compounds entering the balance tank.

[0010] Optionally, a condensate discharge device is connected to the bottom of the balance tank; the condensate discharge device includes a condensate transfer pump and a level sensor for detecting the condensate level in the balance tank, and both the level sensor and the condensate transfer pump are communicatively connected to a level controller; when the level sensor detects that the condensate level reaches a high level set value, the level controller controls the condensate transfer pump to start discharging; when the level sensor detects that the condensate level drops to a low level set value, the level controller controls the condensate transfer pump to stop.

[0011] Optionally, at least a portion of the outer surface of any of the storage tanks is covered with a heat-insulating layer or coated with a heat-insulating and reflective coating.

[0012] Optionally, the gas phase balance pipe is provided with a branch pressure tap and a differential pressure regulator; one end of the branch pressure tap is connected to the gas phase balance pipe, and the other end is connected to the bottom gas phase space of the balance tank; the differential pressure regulator includes a first regulating valve provided on the branch pressure tap, a second regulating valve provided on the gas phase balance pipe, and a first pressure sensor and a second pressure sensor respectively detecting the top and bottom gas phase spaces of the balance tank; the first pressure sensor, the second pressure sensor, the first regulating valve, and the second regulating valve are all communicatively connected to the differential pressure controller, and the differential pressure controller dynamically adjusts the opening of the first regulating valve and the second regulating valve according to the pressure difference between the top and bottom of the balance tank to optimize the gas phase flow field distribution inside the balance tank.

[0013] Optionally, a pressurization device is provided downstream of the gas phase discharge pipe; the pressurization device includes a Venturi ejector connected in parallel to the gas phase discharge pipe, and a pressure relief bypass connected to the drive port of the Venturi ejector; the other end of the pressure relief bypass is connected to the outlet of the tank top breather valve. When the tank top breather valve of any of the storage tanks is activated to discharge high-pressure gas, the discharged high-pressure gas enters the Venturi ejector through the pressure relief bypass as a power source, ejecting and pressurizing the main gas flow from the gas phase discharge pipe.

[0014] Optionally, the gas phase balance pipe includes at least two gas phase branches, each of which is connected to at least two storage tanks in a one-to-one correspondence. Each gas phase branch is equipped with a detection unit. The detection unit includes a sampling probe, an online analyzer connected to the sampling probe via a pipeline, and a data controller. The sampling probe periodically collects gas samples from its respective gas phase branch and transmits them to the online analyzer for real-time analysis of volatile organic compound components and concentrations to generate analytical data. The data controller receives the analytical data and generates an early warning signal and locates the abnormal storage tank when an abnormality is detected.

[0015] This application also provides an oil and gas treatment method based on the VOCs balance tank system with pressure gradient design described in any one of the above, including the following steps: a collection and buffering step: volatile organic compounds generated by feed or temperature changes in each storage tank are transported to the balance tank for mixing and temporary storage through their respective corresponding gas phase balance pipes; a pressure interlock emission step: the pressure at the top of the balance tank is monitored in real time, and when the pressure at the top of the tank reaches a preset emission interlock value of 2.8 kPaG, the switch valve on the gas phase emission pipe is opened, and the buffered and pretreated gas in the balance tank automatically flows to the downstream treatment device due to the static pressure inside the balance tank.

[0016] The above technical solution has the following beneficial effects: The VOCs balancing tank system and oil and gas treatment method with pressure gradient design provided in this application establish a pressure gradient from the storage tank to the balancing tank and then to the downstream equipment. By precisely setting multiple pressure control points, including the exhaust pressure of the tank top breather valve ≥3.8 kPaG, the release pressure of the emergency pressure relief device ≥5.8 kPaG, the exhalation pressure of the single exhalation valve on the gas phase balancing pipe ≥2.8 kPaG, and the interlock pressure of the balancing tank's second discharge ≥2.8 kPaG, a coordinated pressure protection and gas guidance network is constructed from low-pressure normal operating conditions to high-pressure emergency operating conditions. This mechanism ensures that under normal fluctuations, volatile organic compounds in the storage tank are preferentially collected in an orderly manner through the single exhalation valve and the balancing tank, avoiding raw material waste and reducing production costs. Under abnormally high pressure, the tank top breather valve and the emergency pressure relief device are activated step by step to ensure equipment safety. Simultaneously, the balancing tank, as the buffer core, matches its discharge pressure with the single exhalation valve pressure, achieving linkage between collection and discharge. Furthermore, the entire flow process of volatile organic compound gas from the storage tank to the balance tank and then to the downstream treatment unit relies entirely on the static pressure energy generated by the preset pressure gradient difference between the storage tank and the balance tank, and between the balance tank and the downstream unit. This eliminates the need for traditional mechanical conveying fans, which not only achieves energy saving but also eliminates the safety risks of fire and explosion caused by the blower as a potential ignition source. Attached Figure Description

[0017] The preferred embodiments of this application will now be described in detail with reference to the accompanying drawings to help understand the purpose and advantages of this application, wherein...

[0018] Figure 1 A schematic diagram of a VOCs balancing tank system with pressure gradient design provided as an optional embodiment of this application.

[0019] Figure 2 This is a flowchart of an optional embodiment of the oil and gas processing method provided in this application.

[0020] Explanation of reference numerals in the attached figures: 1-Storage tank, 10-Gas phase balance pipe, 100-Gas phase branch pipe, 11-Tank top breather valve, 2-Balance tank, 20-Gas phase discharge pipe, 21-Switch valve, 22-Pressure transmitter, 23-Gas pressure controller, 24-Condensate coil, 25-Condensate transfer pump, 26-Level controller. Detailed Implementation

[0021] The technical solution of the present invention will be further described in detail below with reference to embodiments and accompanying drawings. The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the structures shown in the accompanying drawings. The terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. These directional terms are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive terms.

[0022] The VOCs balancing tank system with pressure gradient design provided in this application, such as Figure 1 As shown, it includes: at least two storage tanks 1 and a balance tank 2.

[0023] Each of the aforementioned storage tanks 1 is equipped with a tank top breather valve 11 and an emergency pressure relief device. The exhaust pressure of the tank top breather valve 11 is not less than 3.8 kPaG. When the internal pressure of the storage tank 1 rises to not less than 3.8 kPaG, the tank top breather valve 11 will open to exhale, serving as one of the release channels to prevent overpressure of the storage tank 1. The release pressure of the emergency pressure relief device is not less than 5.8 kPaG. The emergency pressure relief device can be selected as a pilot-operated safety valve. When the release capacity of the tank top breather valve 11 is insufficient to prevent the pressure from rising further, the emergency pressure relief device is activated as the final protective barrier to quickly release pressure.

[0024] The balancing tank 2 is connected to the gas phase space of at least two of the storage tanks 1 via a gas phase balancing pipe 10, and is used to receive and buffer volatile organic compounds from each of the storage tanks 1. The gas phase balancing pipe 10 is equipped with a single exhalation valve, and the exhalation pressure of the single exhalation valve is greater than or equal to 2.8 kPaG. When the pressure in the storage tank 1 reaches 2.8 kPaG, the high-pressure gas in the storage tank 1 is directed to the balancing tank 2. This design ensures that under most operating conditions, the pressure generated by the feeding or temperature rise in the storage tank 1 first pushes the single exhalation valve to open, directing the gas to the closed balancing tank 2, rather than directly venting it into the atmosphere through the tank top breather valve 11. This reduces the operating frequency of the tank top breather valve 11 and the fugitive emissions, which helps maintain the pressure stability and media purity of the gas phase space of the storage tank 1, and improves the regional environmental safety level and material storage quality.

[0025] The top of the balance tank 2 is connected to a gas phase discharge pipe 20, and a switch valve 21 is installed on the gas phase discharge pipe 20. When the internal pressure of the balance tank 2 is greater than or equal to 2.8 kPaG, the switch valve 21 opens. Driven by the pressure difference, the gas phase discharge pipe 20 transports volatile organic compounds to the downstream processing device.

[0026] Optionally, the design pressure of any of the storage tanks 1 is -0.49 / 6.5 kPaG, and the intake pressure of the breather valve 11 on the top of the tank is less than or equal to -0.3 kPaG, so as to achieve the intrinsic safety of the storage tank 1.

[0027] This embodiment of the application establishes a pressure gradient from storage tank 1 to balance tank 2 and then to downstream equipment through the above design: by precisely setting multiple pressure control points, such as the exhaust pressure of the breather valve 11 on the top of storage tank 1 ≥ 3.8 kPaG, the release pressure of the emergency pressure relief device ≥ 5.8 kPaG, the exhalation pressure of the single exhalation valve on the gas phase balance pipe 10 ≥ 2.8 kPaG, and the discharge interlock pressure of balance tank 2 ≥ 2.8 kPaG, a coordinated pressure protection and gas guidance network is constructed from low-pressure normal operating conditions to high-pressure emergency operating conditions. This mechanism ensures that under normal fluctuations, volatile organic compounds in storage tank 1 are preferentially collected in an orderly manner through the single exhalation valve to balance tank 2; under abnormal high pressure, the breather valve 11 on the top of the tank and the emergency pressure relief device are activated step by step to ensure equipment safety; at the same time, balance tank 2, as the buffer core, matches its discharge pressure with the single exhalation valve pressure, realizing the linkage between collection and discharge. Furthermore, the entire flow process of volatile organic compound gas from storage tank 1 to balance tank 2 and then to the downstream treatment device relies entirely on the static pressure energy generated by the preset pressure gradient difference between storage tank 1 and balance tank 2, and between balance tank 2 and the downstream device. This eliminates the need for traditional mechanical conveying fans, which not only achieves energy saving but also eliminates the safety risks of fire and explosion caused by the blower as a potential ignition source.

[0028] In an optional embodiment, each of the storage tanks 1 is further equipped with a nitrogen sealing system. The nitrogen sealing system maintains a slight positive pressure in the gas phase space of the storage tank 1. The nitrogen sealing system includes a nitrogen supply pipe connected to the gas phase space of the storage tank 1. The nitrogen supply pipe is open when the pressure in the gas phase space of the storage tank 1 is less than or equal to 0.2 kPaG, and closed when the pressure is greater than or equal to 0.5 kPaG. A nitrogen sealing valve is installed on the nitrogen supply pipe. The nitrogen supply valve opens to supply nitrogen when the pressure in the gas phase space of the storage tank 1 is less than 0.2 kPaG; the nitrogen supply valve closes when the pressure in the gas phase space of the storage tank 1 is greater than 0.5 kPaG, thereby ensuring that the pressure inside the storage tank 1 is always higher than atmospheric pressure, physically preventing the infiltration of external air (including oxygen and water vapor). These gases are then transported to the balance tank 2 through the gas phase balance pipe 10.

[0029] Furthermore, the inhalation pressure setting of the tank top breather valve 11 (-0.3 kPaG) is lower than the opening pressure setting of the nitrogen replenishment valve (0.2 kPaG), forming a "nitrogen sealing priority" logic. Under normal circumstances, a pressure drop will first trigger nitrogen replenishment. Only when the nitrogen sealing system is insufficient or malfunctioning will the tank top breather valve 11 be triggered to inhale, minimizing the possibility of air intake.

[0030] In one alternative implementation, such as Figure 1 As shown, a pressure transmitter 22 is installed on the top of the balance tank 2. Both the switching valve 21 and the pressure transmitter 22 are communicatively connected to a pressure controller 23. When the pressure transmitter 22 detects that the pressure at the top of the balance tank 2 is equal to or greater than 2.8 kPaG, the pressure controller 23 controls the switching valve 21 to open. When the pressure transmitter 22 detects that the pressure at the top of the balance tank 2 is lower than a set closing value (e.g., 2.5 kPaG), the pressure controller 23 controls the switching valve 21 to close. The pressure controller 23 can be a control module located in a control room. This embodiment of the application achieves automated and precise control of the emission process, ensuring that the emission action strictly follows the preset pressure gradient and avoiding human error or delay. The pressure transmitter 22 provides continuous feedback, making the control more precise.

[0031] In one alternative implementation, such as Figure 1 As shown, the balance tank 2 is equipped with a condenser coil 24, through which a cooling medium flows to cool the volatile organic compounds entering the balance tank 2. The low temperature causes higher-boiling-point VOCs components (such as heavy hydrocarbons) in the gas to condense into liquid, achieving preliminary condensation recovery. This not only recovers some valuable materials but also significantly reduces the gas load and concentration entering downstream processing units, improving overall processing efficiency and economy. The condensation process itself also helps lower the gas phase temperature inside the balance tank 2, helping to suppress the pressure inside the tank.

[0032] Optionally, the condenser coil 24 is made of corrosion-resistant materials such as stainless steel and is arranged in the form of a coil or tube, and can be located in the upper middle part of the balance tank 2. The inlet and outlet pipes of the condenser coil 24 pass through the side wall of the balance tank 2 and are connected to an external circulating cooling system (such as a refrigeration unit or cooling water system) to introduce a cooling medium (such as chilled water or ethylene glycol solution).

[0033] Furthermore, an electric regulating valve and a temperature sensor are installed on the cooling medium pipeline of the condenser coil 24 and connected to a temperature controller. The temperature sensor monitors the outlet medium temperature of the condenser coil 24. The temperature controller dynamically controls the flow rate of the cooling medium by adjusting the opening of the electric regulating valve based on the deviation between the outlet medium temperature and the set value, or by adjusting the cooling power of the circulating cooling system through commands, thereby achieving optimized control of condensation intensity and reducing energy consumption while ensuring condensate recovery rate.

[0034] In an optional embodiment, the bottom of the balance tank 2 is connected to a condensate discharge device; such as Figure 1As shown, the condensate discharge device includes a condensate transfer pump 25 and a level sensor for detecting the condensate level in the balance tank 2. Both the level sensor and the condensate transfer pump 25 are communicatively connected to a level controller 26. When the level sensor detects that the condensate level reaches a high level set value, the level controller 26 controls the condensate transfer pump 25 to start discharging. When the level sensor detects that the condensate level drops to a low level set value, the level controller 26 controls the condensate transfer pump 25 to stop. This embodiment of the application achieves automatic, on-demand discharge of condensate, preventing excessively high levels in the balance tank 2 from affecting the volume of the top gas phase space or even causing liquid to be carried into the gas phase pipeline. Simultaneously, automated operation avoids the lag and oversight of manual intervention, ensuring the continuous and stable operation of the condensate system and preventing liquid carryover in the gas phase.

[0035] In an optional embodiment, at least a portion of the outer surface of any of the storage tanks 1 is covered with a thermal insulation layer or coated with a thermal reflective coating. The thermal insulation layer may be selected from materials such as rock wool, glass wool with aluminum foil, etc., and the thermal reflective coating may be selected from special coatings with high solar reflectivity and hemispherical emissivity. The embodiments of this application can effectively reduce the increase in internal temperature of the storage tank 1 caused by external heat sources such as solar radiation, thereby significantly suppressing the volatilization of VOCs gas generated by the "small breathing" effect, reducing the amount of waste gas that needs to be treated from the source, and reducing the system load.

[0036] In an optional embodiment, the gas phase balance pipe 10 is provided with a branch pressure tap and a differential pressure regulator; one end of the branch pressure tap is connected to the gas phase balance pipe 10, and the other end can be connected to the bottom gas phase space of the balance tank 2 through an interface opened at the bottom of the side wall of the balance tank 2; the differential pressure regulator includes a first regulating valve provided on the branch pressure tap, a second regulating valve provided on the gas phase balance pipe 10, and a first pressure sensor and a second pressure sensor respectively detecting the top gas phase space and the bottom gas phase space of the balance tank 2; the first pressure sensor, the second pressure sensor, the first regulating valve and the second regulating valve are all communicatively connected to the differential pressure controller, and the differential pressure controller dynamically adjusts the opening of the first regulating valve and the second regulating valve according to the pressure difference between the top and the bottom of the balance tank 2, so as to optimize the gas phase flow field distribution inside the balance tank 2. For example, if the pressure difference between the top and bottom gas phase spaces of the balance tank 2 is too small, there may be a short circuit in the gas flow, that is, the gas entering from the top space of the balance tank 2 is directly discharged from the top space. At this time, the second regulating valve can be closed and the first regulating valve can be opened to guide some gas flow into the bottom of the balance tank 2, promote the vertical mixing of the gas in the balance tank 2, achieve homogenization of the gas, and at the same time push the gas to move from bottom to top, prolonging the effective residence time of the gas in the balance tank 2.

[0037] Furthermore, a target differential pressure value ΔP_set can be set within the differential pressure controller, for example, 200 Pa (this value needs to be determined experimentally or through simulation based on the height of the balance tank 2, the design flow rate, and process requirements); the pressure value detected by the first pressure sensor is P_top, and the pressure value detected by the second pressure sensor is P_bottom. The controller continuously calculates the real-time differential pressure ΔP_real = P_top - P_bottom. Using a PID (Proportional-Integral-Derivative) algorithm, ΔP_real tracks ΔP_set by adjusting the opening degrees of the first and second regulating valves.

[0038] In an optional embodiment, a pressurization device is provided downstream of the gas phase discharge pipe 20; the pressurization device includes a Venturi ejector connected in parallel to the gas phase discharge pipe 20, and a pressure relief bypass connected to the drive port of the Venturi ejector; the other end of the pressure relief bypass is connected to the outlet of the tank top breather valve. When the tank top breather valve of any of the storage tanks 1 is activated to discharge high-pressure gas, the discharged high-pressure gas enters the Venturi ejector through the pressure relief bypass as a power source. This high-speed airflow will generate negative pressure at the throat of the Venturi ejector, ejecting the main airflow from the gas phase discharge pipe 20 and pressurizing the mixed gas, and then discharge them together to the downstream processing device, thereby increasing the gas pressure and flow rate delivered to the downstream processing device without the need for a mechanical fan.

[0039] In an optional embodiment, the gas phase balance pipe 10 includes at least two gas phase branches 100, each of which is connected to at least two storage tanks 1 in a one-to-one correspondence. Each gas phase branch 100 is equipped with a detection unit, which includes a sampling probe, an online analyzer connected to the sampling probe via a pipeline, and a data controller. The sampling probe periodically collects gas samples from the gas phase branch 100 it is located in and transmits them to the online analyzer for real-time analysis of volatile organic compound components and concentrations to generate analytical data. The data controller receives the analytical data, and when an abnormality is detected in the analytical data, such as an unexpected sudden change in material components or concentrations, the data controller generates an early warning signal and identifies the storage tank 1 connected to the gas phase branch 100 where the sampling probe is located as an abnormal storage tank 1. The embodiments of this application can realize refined online monitoring of VOCs collection sources, and can detect potential leaks in storage tank 1 (such as failure of internal floating roof seal), material mixing errors or process abnormalities at an early stage, so as to achieve rapid location and early warning, and improve the level of proactive safety management and environmental risk supervision capabilities of storage tank 1 area.

[0040] This application also provides an oil and gas treatment method based on the VOCs balance tank system with pressure gradient design described in any of the above embodiments, such as... Figure 2As shown, it includes the following steps.

[0041] S1: Collection and buffering step: Volatile organic compounds generated by each storage tank 1 due to feeding or temperature changes are collected through their respective gas phase balance pipes 10 and transported to the balance tank 2 for mixing and temporary storage and buffering.

[0042] S2: Pressure interlock discharge step: Monitor the pressure at the top of the balance tank 2 in real time. When the pressure reaches the preset 2.8 kPaG discharge interlock value, open the switch valve 21 on the gas phase discharge pipe 20. The gas in the tank that has been buffered and pretreated will automatically flow to the downstream treatment device by relying on its own static pressure.

[0043] Optionally, the following steps may be included after the buffer collection step S1.

[0044] S3: Condensation pretreatment step: The mixed gas entering the balance tank 2 exchanges heat with the condenser coil 24 installed in the balance tank 2, and some volatile organic compound components are condensed into liquid, achieving preliminary recovery.

[0045] Optionally, the following steps may be included after the pressure interlock discharge step S2.

[0046] S4: Automatic condensate discharge step: Real-time monitoring of the condensate level in the balance tank 2. When the level reaches the high level set value, the condensate transfer pump 25 starts to discharge the condensate; when the level drops to the low level set value, the condensate transfer pump 25 stops running.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A VOCs balancing tank system with a pressure gradient design, characterized in that, include: At least two storage tanks, each of which is equipped with a tank top breather valve and an emergency pressure relief device, wherein the exhaust pressure of the tank top breather valve is not less than 3.8 kPaG and the release pressure of the emergency pressure relief device is not less than 5.8 kPaG; A balance tank, connected to the gas phase space of at least two of the storage tanks via a gas phase balance pipe, is used to receive and buffer volatile organic compounds from each of the storage tanks. A single exhale valve is provided on the gas phase balance pipe, and the exhale pressure of the single exhale valve is greater than or equal to 2.8 kPaG. The top of the balance tank is connected to a gas phase emission pipe, which is equipped with a switch valve. When the internal pressure of the balance tank is greater than or equal to 2.8 kPaG, the switch valve opens, and the gas phase emission pipe transports volatile organic compounds to the downstream treatment device.

2. The VOCs balancing tank system with pressure gradient design according to claim 1, characterized in that, Any of the aforementioned storage tanks is also equipped with a nitrogen blanketing system, wherein: The nitrogen sealing system includes a nitrogen supply pipe connected to the gas phase space. The nitrogen supply pipe is opened when the pressure of the gas phase space is less than or equal to 0.2 kPaG and closed when the pressure of the gas phase space is greater than or equal to 0.5 kPaG.

3. The VOCs balancing tank system with pressure gradient design according to claim 1, characterized in that, A pressure transmitter is installed on the top of the balance tank; Both the switching valve and the pressure transmitter are communicatively connected to the pressure controller. When the pressure transmitter detects that the pressure at the top of the balance tank is equal to or greater than 2.8 kPaG, the pressure controller controls the switching valve to open.

4. The VOCs balancing tank system with pressure gradient design according to claim 1, characterized in that, The balance tank is equipped with a condenser coil, which is filled with a cooling medium to cool the volatile organic compounds entering the balance tank.

5. The VOCs balancing tank system with pressure gradient design according to claim 1, characterized in that, The bottom of the balance tank is connected to a condensate discharge device; The condensate discharge device includes a condensate transfer pump and a level sensor for detecting the condensate level in the balance tank. Both the level sensor and the condensate transfer pump are communicatively connected to the level controller. When the level sensor detects that the condensate level has reached the high level set value, the level controller controls the condensate transfer pump to start draining the condensate; when the level sensor detects that the condensate level has dropped to the low level set value, the level controller controls the condensate transfer pump to stop.

6. The VOCs balancing tank system with pressure gradient design according to claim 1, characterized in that, At least a portion of the outer surface of any of the aforementioned storage tanks is covered with a heat-insulating layer or coated with a heat-insulating and reflective coating.

7. The VOCs balancing tank system with pressure gradient design according to any one of claims 1-6, characterized in that, The gas phase balance tube is equipped with a branch pressure tap and a differential pressure regulator. One end of the branch pressure tap is connected to the gas phase balance pipe, and the other end is connected to the bottom gas phase space of the balance tank; the differential pressure regulator includes a first regulating valve installed on the branch pressure tap, a second regulating valve installed on the gas phase balance pipe, and a first pressure sensor and a second pressure sensor respectively detecting the top gas phase space and the bottom gas phase space of the balance tank. The first pressure sensor, the second pressure sensor, the first regulating valve, and the second regulating valve are all communicatively connected to the differential pressure controller. The differential pressure controller dynamically adjusts the opening of the first regulating valve and the second regulating valve according to the pressure difference between the top and bottom of the balance tank, so as to optimize the gas phase flow field distribution inside the balance tank.

8. The VOCs balancing tank system with pressure gradient design according to any one of claims 1-6, characterized in that, A booster device is installed downstream of the gas phase emission pipe; The pressurization device includes a Venturi ejector connected in parallel to the gas phase discharge pipe, and a pressure relief bypass connected to the drive port of the Venturi ejector; the other end of the pressure relief bypass is connected to the outlet of the breather valve on the top of the buffer tank. When the breather valve on the top of any of the storage tanks is activated to discharge high-pressure gas, the discharged high-pressure gas enters the Venturi ejector through the pressure relief bypass as a power source, ejecting and pressurizing the main airflow from the gas phase discharge pipe.

9. The VOCs balancing tank system with pressure gradient design according to any one of claims 1-6, characterized in that, The gas phase balance pipe includes at least two gas phase branches, and the at least two gas phase branches are connected to at least two storage tanks in a one-to-one correspondence. Each gas phase branch is equipped with a detection unit. The detection unit includes a sampling probe, an online analyzer connected to the sampling probe via a pipeline, and a data controller; the sampling probe periodically collects gas samples from the gas phase branch pipe in which it is located and delivers them to the online analyzer for real-time analysis of volatile organic compound components and concentrations to generate analytical data; The data controller receives the analysis data, and when it detects an anomaly in the analysis data, it generates an early warning signal and locates the abnormal storage tank.

10. A method for oil and gas processing, characterized in that, The VOCs balancing tank system with pressure gradient design according to any one of claims 1-9 includes the following steps. Collection and buffering steps: Volatile organic compounds generated in each storage tank due to feeding or temperature changes are transported to the balance tank through their respective gas phase balance pipes for mixing and temporary storage; Pressure interlock discharge procedure: The pressure at the top of the balance tank is monitored in real time. When the pressure at the top of the tank reaches the preset discharge interlock value of 2.8 kPaG, the switch valve on the gas phase discharge pipe is opened. The gas in the balance tank that has been buffered and pretreated flows automatically to the downstream treatment device by relying on the static pressure inside the balance tank.

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