Gas field atmospheric storage tank VOCs treatment system and method

Abstract

The invention discloses a gas field atmospheric storage tank VOCs treatment system and method, and belongs to the technical field of gas field atmospheric storage tank volatile gas treatment, the system comprises a PLC control system, and a separation buffer system, a gas supply system and an automatic liquid discharge system which are electrically connected with the PLC control system; the whole system is controlled through the PLC control system, volatile gas enters the separation buffer system from the normal-pressure storage tank and is sequentially subjected to buffer, pressurization and separation treatment, meanwhile, gas is supplemented to the separation buffer system through the gas supplementing system, and a liquid phase obtained through separation is automatically discharged through the automatic liquid discharging system; the VOCs in the atmospheric storage tank are automatically treated in real time, the treatment effect is improved, and meanwhile the overall treatment efficiency is improved; by adopting the system, a large amount of natural gas can be effectively recovered, the production cost is reduced, and the economic benefit is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of volatile gas treatment in atmospheric pressure storage tanks of gas fields, and in particular relates to a VOCs treatment system and method for atmospheric pressure storage tanks of gas fields. Background Art

[0002] At present, atmospheric pressure storage tanks in gas fields often volatilize. The main reason for the volatilization of atmospheric pressure storage tanks is that the real vapor pressure of the storage medium is high. When the outside temperature rises, the light components in the medium volatilize into gas, causing the pressure of the storage tank to increase and exhale from the breathing valve; at the same time, when the storage tank is filled with liquid, the gas phase space in the tank is reduced, which will also cause the volatile gas to exhale. The volatile gas of atmospheric pressure storage tanks is an unorganized emission, and the gas volume is not measured.

[0003] As an important precursor of PM2.5 and O3, volatile organic compounds have become one of the important factors leading to severe smog weather and are a constant threat to human health. In addition to causing harm to the human body, some volatile organic compound waste gases, when discharged into the atmosphere, will also damage the ozone layer, aggravate the greenhouse effect, and trigger global climate disasters.

[0004] In the existing volatile gas control measures for atmospheric pressure storage tanks, since the various modules are relatively scattered and lack of systematicity, it is impossible to carry out real-time automatic control of VOCs in atmospheric pressure storage tanks, resulting in unclear VOCs control effects and low work efficiency. Summary of the invention

[0005] In order to overcome the above technical defects, the present invention provides a VOCs treatment system and method for atmospheric pressure storage tanks in gas fields, which can solve the technical problems that the existing atmospheric pressure storage tank volatile gas treatment measures are difficult to carry out real-time automatic treatment of VOCs in atmospheric pressure storage tanks, resulting in poor treatment effect and low work efficiency.

[0006] In order to achieve the above object, the present invention adopts the following technical contents:

[0007] A VOCs treatment system for atmospheric pressure storage tanks in gas fields, comprising a PLC control system and a separation buffer system connected to the atmospheric pressure storage tank, wherein the separation buffer system is used to separate volatile gas from the atmospheric pressure storage tank; the separation buffer system is connected to an air supply system for air source supply and an automatic liquid discharge system for automatically discharging a liquid phase;

[0008] The PLC control system is electrically connected to the separation buffer system, the air supply system and the automatic liquid discharge system respectively.

[0009] Furthermore, the exhalation discharge ports on the tank tops of the plurality of atmospheric pressure storage tanks are connected via a gas phase pipeline and connected in parallel to the separation buffer system.

[0010] Furthermore, a pressure detection device is provided on the tank top of the atmospheric pressure storage tank for real-time monitoring of the pressure value of the atmospheric pressure storage tank, and the pressure detection device is electrically connected to the PLC control system.

[0011] Furthermore, the separation buffer system, the air supply system and the automatic liquid drainage system are designed in a skid-mounted form.

[0012] Furthermore, the separation buffer system includes a pressure stabilizing tank; the input end of the pressure stabilizing tank is connected to the atmospheric pressure storage tank, and the output end is connected to the exhaust compressor; the exhaust compressor is connected to the separator; the output end of the separator is connected to the flash recovery system located downstream.

[0013] Furthermore, the other output end of the separator and the pressure-surge tank form an air replenishment loop.

[0014] Furthermore, the external gas source input end of the pressure-stabilizing tank is connected to the gas supply system.

[0015] Furthermore, the automatic drainage system includes an unstabilized condensate tank, and the drainage end of the separation buffer system is connected to the unstabilized condensate tank via a pump.

[0016] A working method of a VOCs treatment system for a gas field atmospheric pressure storage tank based on the above-mentioned method comprises:

[0017] Through the control of the PLC control system, the volatile gas enters the separation buffer system from the atmospheric pressure storage tank, and is buffered, pressurized and separated in turn. At the same time, the separation buffer system is replenished with air through the air replenishment system, and the separated liquid phase is automatically discharged by the automatic liquid discharge system.

[0018] Furthermore, the volatile gas enters the pressure stabilizing tank, and after the liquid phase is separated by the pressure stabilizing tank, the volatile gas separated by the pressure stabilizing tank is pressurized to 300-400 kPa. The pressurized volatile gas is cooled to 30-50°C by the air cooler at the outlet of the exhaust compressor and then enters the separator. Part of the separated gas phase enters the pressure stabilizing tank, and the other part enters the flash gas recovery system.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention provides a VOCs treatment system for atmospheric pressure storage tanks in gas fields. The system comprises a PLC control system and a separation buffer system, an air supply system and an automatic liquid discharge system which are respectively electrically connected to the PLC control system. The entire system is controlled by the PLC control system, volatile gas enters the separation buffer system from the atmospheric pressure storage tank, and the volatile gas is sequentially buffered, pressurized and separated. At the same time, air is supplied to the separation buffer system by the air supply system, and the separated liquid phase is automatically discharged by the automatic liquid discharge system. Real-time automatic treatment of VOCs in atmospheric pressure storage tanks is achieved, which not only improves the treatment effect, but also improves the overall treatment efficiency. The system can realize the effective recovery of a large amount of natural gas, reduce production costs and improve economic benefits.

[0021] Preferably, in the present invention, the exhalation discharge port on the tank top of the atmospheric pressure storage tank is connected by a gas phase pipeline and connected in parallel to the separation buffer system, thus eliminating the traditional nitrogen sealing method of the storage tank and ensuring the sealing effect.

[0022] Preferably, in the present invention, a pressure detection device is provided on the tank top of the atmospheric pressure storage tank for real-time monitoring of the pressure value of the atmospheric pressure storage tank, so as to monitor the pressure value of the atmospheric pressure storage tank in real-time and transmit the monitoring data to the PLC control system in real time, and the PLC control system performs online regulation and control of each system according to the monitoring data.

[0023] Preferably, in the present invention, the separation buffer system, the air supply system and the automatic liquid discharge system are designed in a skid-mounted form, which can greatly save floor space and construction period.

[0024] Preferably, in the present invention, the separation buffer system includes a pressure-stabilizing tank, an exhaust compressor and a separator. During operation, the volatile gas enters the pressure-stabilizing tank, and after the liquid phase is separated by the pressure-stabilizing tank, the volatile gas separated by the pressure-stabilizing tank is pressurized to 300-400 kPa. The pressurized volatile gas is cooled to 30-50° C. by an air cooler at the outlet of the exhaust compressor and then enters the separator. The separated gas phase enters the flash gas recovery system, thereby ensuring the effective recovery of a large amount of natural gas.

[0025] Further preferably, the other output end of the separator forms an air replenishment loop with the pressure-regulating tank, so that cyclic air replenishment can be performed according to the air pressure in the pressure-regulating tank, providing another air replenishment input source for the pressure-regulating tank, thereby realizing effective utilization of the separated gas phase.

[0026] Further preferably, the external gas source input end of the pressure-stabilizing tank is connected to the air supply system, which is equivalent to introducing a fuel gas as the air supply source of the pressure-stabilizing tank, thereby preventing negative pressure from forming in the storage tank when the storage tank breathes heavily, and ensuring the effective discharge of volatile gas.

[0027] The present invention also provides a working method of a VOCs treatment system for a gas field atmospheric pressure storage tank. Based on the above-mentioned VOCs treatment system for a gas field atmospheric pressure storage tank, the method controls the volatile gas from the atmospheric pressure storage tank to enter the separation buffer system, and sequentially performs buffering, pressurization and separation treatments on the volatile gas. At the same time, the separation buffer system is replenished with gas through the gas replenishment system, and the separated liquid phase is automatically discharged by the automatic liquid discharge system. The method can realize real-time automatic treatment of VOCs in the atmospheric pressure storage tank, avoid waste of resources, eliminate safety hazards, protect the environment, and meet regulatory requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the structure of a VOCs treatment system for a gas field atmospheric pressure storage tank provided by an embodiment of the present invention;

[0029] Reference numerals:

[0030] Atmospheric pressure storage tank-1; Pressure stabilizing tank-2; Air extraction compressor-3; Separator-4; Air cooler-5;

[0031] Pressure sensor-1-1; pressure alarm valve-1-2; electric valve-1-3. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail in the following specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0036] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0037] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0038] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0040] Example

[0041] As mentioned in the background technology, the existing volatile gas control measures for atmospheric pressure storage tanks are unable to perform real-time automatic control of VOCs in atmospheric pressure storage tanks due to the relatively scattered modules and lack of systematicness, resulting in unclear VOCs control effects and low work efficiency.

[0042] In order to solve the above technical problems, the present embodiment provides a system and method for VOCs treatment in atmospheric pressure storage tanks of gas fields. The system and method are adopted to solve the problem that the existing volatile gas treatment measures in atmospheric pressure storage tanks are difficult to carry out real-time automatic treatment of VOCs in atmospheric pressure storage tanks, resulting in poor treatment effect and low work efficiency.

[0043] The specific structure of this embodiment is described in detail below in conjunction with the accompanying drawings:

[0044] like Figure 1 As shown, this embodiment provides a VOCs treatment system for a gas field atmospheric pressure storage tank, including a PLC control system, a separation and buffer system, an air supply system and an automatic liquid discharge system.

[0045] The PLC control system is responsible for controlling the separation and buffer system, the air supply system and the automatic drainage system, including the monitoring and early warning of data such as flow, temperature and pressure. The separation and buffer system, the air supply system and the automatic drainage system are regulated according to the monitoring data, so as to achieve the purpose of automatic treatment of VOCs in atmospheric pressure storage tanks (including automatic recovery and automatic discharge).

[0046] Specifically, the PLC control system includes a data acquisition unit, a control unit, and an output instruction unit;

[0047] In this embodiment, the data acquisition unit includes a pressure detection device, such as a pressure sensor 1-1 installed in each atmospheric pressure storage tank 1, and is connected to a pressure alarm valve 1-2. The collected pressure data value is compared with a preset threshold value, and an automatic alarm is realized when the pressure range is exceeded, so as to realize online detection and early warning functions in a fully automatic and unmanned environment, thereby reducing the safety hazards of system operation.

[0048] Electric valves 1-3 are arranged on the gas phase pipeline of multiple atmospheric pressure storage tanks 1 in parallel. The control unit can manipulate all the electrically controlled valves in the system to realize opening and closing or flow regulation. Of course, flow meters and temperature monitors are also required to be arranged on the pipelines that need flow monitoring to monitor the flow and temperature, so that the control unit can obtain data according to the monitoring collection, perform data analysis, and output control instructions to each execution component through the output instruction unit, thereby realizing real-time adjustment of multiple parameters such as temperature, pressure and flow of each pipeline.

[0049] The separation and buffer system is the main component of the atmospheric pressure storage tank VOCs treatment system. It is responsible for the buffering and separation of the volatile gas (VOCs gas) in the atmospheric pressure storage tank 1, that is, it can buffer, pressurize and separate the volatile gas in turn, and output the treated volatile gas to the next working system.

[0050] Among them, the separation buffer system includes a pressure-stabilizing tank 2, an exhaust compressor 3 and a separator 4, and the pressure-stabilizing tank 2, the exhaust compressor 3 and the separator 4 are connected in sequence, the output end of the pressure-stabilizing tank 2 is connected to the exhaust compressor 3, and the output end of the exhaust compressor 3 is connected to the separator 4.

[0051] The pressure regulating tank 2 is mainly responsible for the pressure balance regulation of the whole system, and controls the water pressure of the water inlet pipe and the water outlet pipe to achieve the purpose of stabilizing the pressure of the pipe network.

[0052] The air extraction compressor 3 is mainly responsible for pressurizing the volatile gas. The working process of the air extraction compressor 3 is divided into two parts: suction and compression. During the suction process, the air extraction compressor 3 sucks the volatile gas into the compressor through the air intake valve, and compresses the volatile gas through a piston, a rotary screw or a centrifugal compressor to increase the pressure and temperature of the volatile gas. When the volatile gas is compressed to the target pressure, the compressor discharges the compressed volatile gas through the air cooler 5 into the separator 4.

[0053] The separator 4 is mainly responsible for separating the volatile gas and finally outputting the gas phase obtained after separation to the pressure-surge tank 2 and the flash gas recovery system located downstream.

[0054] The workflow of this system is as follows:

[0055] When the PLC control system in the gas field atmospheric pressure tank VOCs treatment system detects that atmospheric pressure tank VOCs treatment is needed, it first controls the volatile gas of atmospheric pressure tank 1 to be output to the surge tank 2. The surge tank 2 can balance the pressure of the entire system. After the liquid phase is separated by the surge tank 2, the volatile gas is controlled to enter the vacuum compressor 3 for pressurization. At the same time, the volatile gas pressurized by the vacuum compressor 3 is pressure-regulated and returned to the atmospheric pressure tank 1 through the surge tank 2 for gas replenishment. During this period, the control unit controls the fuel gas from the fuel gas system (gas replenishment system) to be connected as the gas replenishment source of the surge tank 2 to prevent the atmospheric pressure tank 1 from forming a negative pressure inside when the atmospheric pressure tank 1 is breathing heavily; the liquid phase of the separator 4 is pumped and transported to the unstable condensate tank to achieve the recovery and treatment of VOCs gas in the atmospheric pressure tank.

[0056] Based on the above-mentioned gas field atmospheric pressure storage tank VOCs treatment system, the optimization of the atmospheric pressure storage tank VOCs treatment process is as follows:

[0057] This system forms an overall treatment process of "multiple tanks in series for volatile gas, separation and buffering, pressurization recovery, and multi-source gas replenishment".

[0058] In addition, the nitrogen sealing of the storage tank is cancelled, and the exhalation discharge ports on the tops of multiple atmospheric pressure storage tanks 1 are connected and collected together by a gas phase pipeline.

[0059] Among them, the pressure stabilization, buffering and air replenishment process is as follows:

[0060] The collected volatile gas enters the surge tank 2, and after the liquid phase is separated by the surge tank 2, it is sent to the air extraction compressor 3 for pressurization. The volatile gas pressurized by the air extraction compressor 3 is pressure-regulated and returned to the atmospheric pressure storage tank 1 through the surge tank 2 for air replenishment. At the same time, a fuel gas is introduced from the fuel gas system (air replenishment system) as the air replenishment source of the surge tank 2 to prevent the atmospheric pressure storage tank 1 from forming a negative pressure when the atmospheric pressure storage tank 1 is breathing heavily; the liquid phase of the separator 4 is pressurized and transported to the unstable condensate tank by the pump.

[0061] The process of air extraction and pressurization is as follows:

[0062] The volatile gas separated by the pressure stabilizing tank 2 is pressurized to 300-400 kPa (absolute pressure), cooled to 30-50°C by the air cooler 5 located at the outlet of the exhaust compressor 3, and then enters the separator 4. Part of the separated gas phase goes to the pressure stabilizing tank 2, and the other part of the volatile gas enters the flash gas recovery system.

[0063] In order to save the floor space of the entire system and shorten the construction period, the above systems are connected in a skid-mounted manner to form a skid-mounted whole. For example, the pressure stabilizing and buffering system and the air supply system are designed as a skid.

[0064] The VOCs treatment system for atmospheric pressure storage tanks in a gas field provided in this embodiment has the following functions: separation and buffering function; gas replenishment function; automatic liquid discharge function; PLC control system. That is, this system is a combination system of large tank gas-liquid separation, natural gas replenishment, flow metering, automatic liquid discharge and other functions.

[0065] This embodiment provides a VOCs treatment system for atmospheric pressure storage tanks in gas fields. Compared with the existing cleaning methods, this embodiment has the following advantages:

[0066] (1) After implementation, each treatment plant can recover 2000-3000m3 of natural gas 3 / d, can significantly reduce production costs and improve economic benefits;

[0067] (2) The system uses a closed process for transportation, and is equipped with a tank top pressure detection system and a tank air supply system, which effectively ensures safe production;

[0068] (3) The pressure stabilizing tank skid and the air extraction compressor skid are installed as a whole, which saves floor space and construction period.

[0069] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention.

Claims

1. A VOCs treatment system for atmospheric pressure storage tanks in gas fields, characterized in that: It includes a PLC control system and a separation buffer system connected to a normal pressure storage tank, the separation buffer system is used to separate the volatile gas of the normal pressure storage tank; the separation buffer system is connected to an air supply system for air source supply and an automatic liquid discharge system for automatically discharging the liquid phase; The PLC control system is electrically connected to the separation buffer system, the air supply system and the automatic liquid discharge system respectively.

2. A VOCs treatment system for atmospheric pressure storage tanks in a gas field according to claim 1, characterized in that: The exhalation discharge ports on the tank tops of the plurality of atmospheric pressure storage tanks are connected via a gas phase pipeline and are connected in parallel to the separation buffer system.

3. A VOCs treatment system for atmospheric pressure storage tanks in a gas field according to claim 1, characterized in that: A pressure detection device is provided on the tank top of the atmospheric pressure storage tank for real-time monitoring of the pressure value of the atmospheric pressure storage tank. The pressure detection device is electrically connected to the PLC control system.

4. A VOCs treatment system for atmospheric pressure storage tanks in a gas field according to claim 1, characterized in that: The separation buffer system, the air supply system and the automatic liquid discharge system are designed in a skid-mounted form.

5. A VOCs treatment system for atmospheric pressure storage tanks in a gas field according to claim 1, characterized in that: The separation buffer system includes a pressure stabilizing tank; the input end of the pressure stabilizing tank is connected to the atmospheric pressure storage tank, and the output end is connected to the air extraction compressor; the air extraction compressor is connected to a separator; the output end of the separator is connected to a flash recovery system located downstream.

6. A VOCs treatment system for atmospheric pressure storage tanks in a gas field according to claim 5, characterized in that: The other output end of the separator and the pressure-suppressing tank form an air supply loop.

7. A VOCs treatment system for atmospheric pressure storage tanks in a gas field according to claim 5, characterized in that: The external gas source input end of the pressure-stabilizing tank is connected to the gas supply system.

8. A VOCs treatment system for atmospheric pressure storage tanks in a gas field according to claim 1, characterized in that: The automatic liquid discharge system comprises an unstabilized condensate oil tank, and the liquid discharge end of the separation buffer system is connected to the unstabilized condensate oil tank via a pump.

9. A working method of a VOCs treatment system for a gas field atmospheric pressure storage tank based on claims 1-8, characterized in that: include: Through the control of the PLC control system, the volatile gas enters the separation buffer system from the atmospheric pressure storage tank, and is buffered, pressurized and separated in turn. At the same time, the separation buffer system is replenished with air through the air replenishment system, and the separated liquid phase is automatically discharged by the automatic liquid discharge system.

10. The working method of a VOCs treatment system for a gas field atmospheric pressure storage tank according to claim 9 is characterized in that: The volatile gas enters the pressure stabilizing tank, and after the liquid phase is separated by the pressure stabilizing tank, the volatile gas separated by the pressure stabilizing tank is pressurized to 300-400kPa. The pressurized volatile gas is cooled to 30-50℃ by the air cooler at the outlet of the exhaust compressor and then enters the separator. Part of the separated gas phase enters the pressure stabilizing tank, and the other part enters the flash gas recovery system.

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