Double-channel oil gas recovery device and channel pre-cooling method thereof

Abstract

The invention discloses a double-channel oil gas recovery device and a channel pre-cooling method thereof, and the method comprises the following steps: a first-stage condensation mechanism and a first-stage condensation mechanism and a second-stage condensation mechanism are used for refrigeration, and oil gas is discharged after being cooled; when the temperature of the oil gas output by the first secondary condensation mechanism is lower than a cryogenic threshold value, the low-temperature oil gas enters the second secondary condensation mechanism through the first switching valve group, and the oil gas is pre-cooled through the cooling capacity of the oil gas; then, the first-stage condensation mechanism stops refrigerating, the second-stage condensation mechanism starts refrigerating, the state of the valve bank is kept, and the output temperature of the first-stage condensation mechanism is larger than or equal to 0 DEG C; thirdly, the first-stage condensation mechanism recovers refrigeration, the oil gas is cooled through the first-stage condensation mechanism and the second-stage condensation mechanism, and the logic is repeated; according to the method disclosed by the invention, the to-be-input secondary condensation mechanism is pre-cooled by utilizing the self cooling capacity of the low-temperature oil gas, a traditional pre-cooling mode depending on a compressor for cooling is replaced, the cooling capacity distribution pressure of a refrigeration system is reduced, and the problem of insufficient cooling capacity caused by the fact that the compressor supplies cold to two channels at the same time is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas recovery devices, and in particular to a dual-channel oil and gas recovery device and a channel precooling method thereof. Background Art

[0002] During the refining, storage and transportation of petroleum, the emission of volatile organic compounds is one of the key issues of environmental regulation. Oil and gas recovery devices are widely used to reduce these emissions. Their working principle is to convert the hydrocarbon medium in the oil and gas from gas to liquid through segmented multi-stage cooling technology, thereby reducing the concentration of VOCs in the oil and gas to meet environmental emission standards. A typical oil and gas recovery device consists of three main parts: refrigeration, defrosting and pre-cooling.

[0003] However, existing oil and gas recovery technologies have some limitations. For example, for oil and gas recovery devices that do not use pre-cooling technology, during operation, when the outlet gasoline temperature is set to -60°C, the oil and gas temperature will rise to above -20°C during channel switching. Under such temperature conditions, most hydrocarbon substances in the oil and gas cannot reach the saturated partial pressure in the low-temperature state, resulting in the outlet concentration of the oil and gas recovery device seriously exceeding the standard and failing to meet environmental emission indicators.

[0004] To solve this problem, a pre-cooling method is adopted in the prior art, that is, before the dual-channel pipeline is switched, a low-temperature refrigerant is used to pre-cool the oil-gas condenser on the other side; however, this pre-cooling method has obvious disadvantages; due to the pre-cooling requirement, during the dual-channel operation, the cooling capacity generated by the compressor needs to be supplied to the oil-gas condensers of the two channels at the same time, which results in insufficient cooling capacity for the running oil-gas condenser; this deficiency will not only cause fluctuations in the operating conditions of the refrigeration system, making the compressor pressure control more complicated, but also reduce the heat exchange efficiency of the oil and gas in the refrigeration circuit, resulting in the oil and gas being unable to be fully condensed, thereby posing a risk of excessive emissions.

[0005] It can be seen that the existing technology still needs to be improved and enhanced. Summary of the Invention

[0006] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a channel pre-cooling method for a dual-channel oil and gas recovery device, which utilizes the cooling capacity of the low-temperature oil and gas itself to pre-cool the secondary condensing mechanism to be put into use, thereby avoiding the problem of insufficient cooling capacity caused by the compressor supplying cooling to two channels at the same time.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A channel pre-cooling method for a dual-channel oil and gas recovery device, the dual-channel oil and gas recovery device includes a primary condensing mechanism, a first and second-level condensing mechanism, and a second-level condensing mechanism, the primary condensing mechanism is connected to the first and second-level condensing mechanism respectively through an inlet valve group, and the first and second-level condensing mechanism and the second and second-level condensing mechanism are arranged in parallel; the output end of the first and second-level condensing mechanism is connected to the input end of the second and second-level condensing mechanism through a first switching valve group; the output end of the second and second-level condensing mechanism is connected to the input end of the first and second-level condensing mechanism through a second switching valve group; the channel pre-cooling method includes: adjusting the opening and closing states of the inlet valve group, the first switching valve group, and the second switching valve group, and controlling the primary condensing mechanism and the first and second-level condensing mechanism to start executing a cooling mode, and the oil and gas are connected to the first and second-level condensing mechanism through the primary condensing mechanism and discharged after cooling down by the first and second-level condensing mechanisms; when the oil and gas temperature at the output end of the first and second-level condensing mechanisms is lower than the preset deep cooling threshold, the opening and closing states of the first switching valve group and the inlet valve group are adjusted so that the oil and gas output by the first and second-level condensing mechanisms enter the second and second-level condensing mechanisms, and the oil and gas are pre-cooled to the second and second-level condensing mechanisms before being discharged; when the preset switching time is reached, the first-level condensing mechanism is controlled to stop executing the refrigeration mode, the opening and closing states of the first switching valve group and the inlet valve group are kept constant, and the second and second-level condensing mechanisms are controlled to start executing the refrigeration mode; when the oil and gas temperature at the output end of the first and second-level condensing mechanisms is ≥0℃, the opening and closing states of the inlet valve group, the first switching valve group and the second switching valve group are adjusted, and the first-level condensing mechanism is controlled to start executing the refrigeration mode, and the oil and gas are discharged after cooling down by the first and second-level condensing mechanisms.

[0009] In the channel pre-cooling method, the oil and gas are discharged after being cooled by the first-level condensing mechanism and the second-level condensing mechanism, and then the method further includes: when the oil and gas temperature at the output end of the second-level condensing mechanism is lower than the preset deep cooling threshold, adjusting the opening and closing states of the second switching valve group and the inlet valve group, so that the oil and gas output by the second-level condensing mechanism enter the first-level condensing mechanism, and the oil and gas are pre-cooled to the first-level condensing mechanism before being discharged; when the preset switching time is reached, the first-level condensing mechanism is controlled to stop executing the refrigeration mode, the opening and closing states of the second switching valve group and the inlet valve group are kept constant, and the first-level condensing mechanism is controlled to start executing the refrigeration mode; when the oil and gas temperature at the output end of the second-level condensing mechanism is ≥0℃, returning to adjust the opening and closing states of the inlet valve group, the first switching valve group and the second switching valve group, and controlling the first-level condensing mechanism and the first-level condensing mechanism to start executing the refrigeration mode.

[0010] In the channel pre-cooling method, the inlet valve group includes a first inlet valve and a second inlet valve, and the first-level condensing mechanism is connected to the first and second-level condensing mechanisms and the second-level condensing mechanism respectively through the first inlet valve and the second inlet valve; the first switching valve group includes a first return air valve and a first outlet valve, the output end of the first and second-level condensing mechanism is connected to the first outlet valve, and is connected to the input end of the second and second-level condensing mechanism through the first return air valve; the second switching valve group includes a second return air valve and a second outlet valve, the output end of the second and second-level condensing mechanism is connected to the second outlet valve, and is connected to the input end of the first and second-level condensing mechanism through the second return air valve; the adjustment of the opening and closing states of the inlet valve group, the first switching valve group and the second switching valve group, and controlling the first-level condensing mechanism and the first and second-level condensing mechanism to start executing the refrigeration mode include: controlling the first inlet valve to open and the first outlet valve to open, and the first return air valve, the second inlet valve, the second outlet valve and the second return air valve are in a closed state; controlling the first-level condensing mechanism and the first and second-level condensing mechanism to start executing the refrigeration mode.

[0011] In the channel pre-cooling method, when the oil and gas temperature at the output end of the first and second-level condensing mechanisms is lower than the preset deep freezing threshold, the opening and closing states of the first switching valve group and the inlet valve group are adjusted so that the oil and gas output by the first and second-level condensing mechanisms enter the second and second-level condensing mechanisms, including: when the oil and gas temperature at the output end of the first and second-level condensing mechanisms is lower than the preset deep freezing threshold, the first outlet valve is controlled to be closed, and the first return air valve and the second outlet valve are controlled to be opened; the oil and gas output by the first and second-level condensing mechanisms enter the second and second-level condensing mechanisms.

[0012] In the channel pre-cooling method, when the oil and gas temperature at the output end of the first and second condensing mechanisms is ≥0°C, the opening and closing states of the inlet valve group, the first switching valve group and the second switching valve group are adjusted, and the first condensing mechanism is controlled to start executing the refrigeration mode, including: when the oil and gas temperature at the output end of the first and second condensing mechanisms is ≥0°C, the second inlet valve and the second outlet valve are controlled to be open, and the first return air valve, the first inlet valve, the first outlet valve and the second return air valve are in the closed state; and the first condensing mechanism is controlled to start executing the refrigeration mode.

[0013] In the channel pre-cooling method, when the oil and gas temperature at the output end of the second-secondary condensing mechanism is lower than the preset deep freezing threshold, the opening and closing states of the second switching valve group and the inlet valve group are adjusted so that the oil and gas output by the second-secondary condensing mechanism enter the first-secondary condensing mechanism, including: when the oil and gas temperature at the output end of the second-secondary condensing mechanism is lower than the preset deep freezing threshold, the second outlet valve is controlled to be closed, and the second return air valve and the first outlet valve are controlled to be opened; the oil and gas output by the second-secondary condensing mechanism enter the first-secondary condensing mechanism.

[0014] The present invention also provides a dual-channel oil and gas recovery device accordingly, which is used to implement any of the channel pre-cooling methods described above. The dual-channel oil and gas recovery device includes a control device and a first-level condensing mechanism, a first-level and second-level condensing mechanism, a second-level and second-level condensing mechanism, an inlet valve group, a first switching valve group, a second switching valve group, a first temperature sensor and a second temperature sensor, which are electrically connected to the control device respectively; the first-level condensing mechanism is connected to the first-level and second-level condensing mechanism respectively through the inlet valve group, and the first-level condensing mechanism and the second-level condensing mechanism are arranged in parallel; the output end of the first-level condensing mechanism is provided with a first temperature sensor, and is connected to the input end of the second-level condensing mechanism through the first switching valve group; the output end of the second-level condensing mechanism is provided with a second temperature sensor, and is connected to the input end of the first-level condensing mechanism through the second switching valve group.

[0015] In the dual-channel oil and gas recovery device, the inlet valve group includes a first inlet valve and a second inlet valve, and the first-level condensing mechanism is respectively connected to the first-level condensing mechanism and the second-level condensing mechanism through the first inlet valve and the second inlet valve; the first switching valve group includes a first return air valve and a first outlet valve, the output end of the first-level condensing mechanism is connected to the first outlet valve, and is connected to the input end of the second-level condensing mechanism through the first return air valve; the second switching valve group includes a second return air valve and a second outlet valve, the output end of the second-level condensing mechanism is connected to the second outlet valve, and is connected to the input end of the first-level condensing mechanism through the second return air valve.

[0016] In the dual-channel oil and gas recovery device, the first-level condensing mechanism includes a first-level oil and gas condenser, the first-level condensing mechanism includes a first-level oil and gas condenser and a first-level oil and gas condenser, and the second-level condensing mechanism includes a second-level oil and gas condenser and a second-level oil and gas condenser; the output end of the first-level oil and gas condenser is connected to the input end of the first-level oil and gas condenser and the input end of the second-level oil and gas condenser through a first inlet valve and a second inlet valve respectively; the output end of the first return gas valve is connected to the input end of the second-level oil and gas condenser or to the input end of the second-level oil and gas condenser; the output end of the second return gas valve is connected to the input end of the first-level oil and gas condenser or to the water end of the first-level oil and gas condenser.

[0017] The dual-channel oil and gas recovery device also includes an exhaust gas heater, and the output end of the first secondary condensing mechanism is connected to the input end of the exhaust gas heater through the first outlet valve; the output end of the second secondary condensing mechanism is connected to the input end of the exhaust gas heater through the second outlet valve.

[0018] Beneficial effects:

[0019] The present invention provides a channel precooling method for a dual-channel oil and gas recovery device, which has the following advantages:

[0020] ① Based on the technical concept of using cold to maintain cold, the system pre-cools the secondary condensing mechanism by utilizing the cooling capacity of low-temperature oil and gas, replacing the traditional pre-cooling method that relies on compressor cooling. This method has the advantage of providing stable cooling capacity to the operating channel. During the switching preparation phase, that is, when the compressor is shut down, the cooled oil and gas is used as the cooling source, reducing the cooling capacity distribution pressure of the refrigeration system and avoiding the problem of insufficient cooling capacity caused by the compressor supplying cooling to two channels at the same time. It can also reduce the cooling capacity consumption of the compressor and improve the overall energy consumption of the dual-channel oil and gas recovery device.

[0021] ② Pre-cooling the secondary condensing mechanism to be put into use by using low-temperature oil and gas can reduce the problem of large temperature fluctuations during switching, ensuring that the oil and gas temperature is always lower than the critical value of the saturation partial pressure of hydrocarbon substances during the switching process, effectively preventing VOCs emissions from exceeding the standard due to temperature rise, and ensuring that the outlet concentration is stable and meets the standard;

[0022] ③ The low-temperature oil and gas not only pre-cools the secondary condensing mechanism to be put into use, ensuring that it can achieve the expected oil and gas processing efficiency during formal operation, but also realizes the secondary separation of gas and liquid through the pre-cooling process, thereby improving the oil and gas recovery efficiency; in addition, the excess cold energy of the low-temperature oil and gas is recovered through pre-cooling, effectively reducing the heating load of the exhaust gas in subsequent treatment, and realizing multiple benefits of cold energy recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A logic flow chart of the channel pre-cooling method provided by the present invention;

[0024] Figure 2 This is a system structure diagram when the first and second condensing mechanisms provided by the present invention perform a cooling mode and the second and second condensing mechanisms perform a pre-cooling mode;

[0025] Figure 3 This is a system structure diagram when the second secondary condensing mechanism provided by the present invention performs a cooling mode and the first secondary condensing mechanism performs a pre-cooling mode;

[0026] Explanation of the main component symbols: 1-first stage oil and gas condenser, 21-first and second stage oil and gas condenser, 22-first and third stage oil and gas condenser, 31-second and second stage oil and gas condenser, 32-second and third stage oil and gas condenser, 41-first inlet valve, 42-second inlet valve, 51-first outlet valve, 52-first return air valve, 61-second outlet valve, 62-second return air valve, 7-exhaust gas heater, 81-first temperature sensor, 82-second temperature sensor, 83-third temperature sensor. DETAILED DESCRIPTION

[0027] The present invention provides a dual-channel oil and gas recovery device and a channel precooling method thereof. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0028] In the description of the present invention, it should be understood that the terms "installation" and "connection" should be understood in a broad sense. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] See also Figures 1 to 3 The present invention provides a channel pre-cooling method for a dual-channel oil and gas recovery device, the dual-channel oil and gas recovery device comprising a primary condensing mechanism, a first-secondary condensing mechanism, and a second-secondary condensing mechanism, the primary condensing mechanism being connected to the first-secondary condensing mechanism and the second-secondary condensing mechanism respectively through an inlet valve group, the first-secondary condensing mechanism and the second-secondary condensing mechanism being arranged in parallel; the output end of the first-secondary condensing mechanism being connected to the input end of the second-secondary condensing mechanism through a first switching valve group; the output end of the second-secondary condensing mechanism being connected to the input end of the first-secondary condensing mechanism through a second switching valve group; the channel pre-cooling method comprises:

[0030] 100. Adjust the opening and closing states of the inlet valve group, the first switching valve group, and the second switching valve group, and control the first condensing mechanism and the first and second condensing mechanisms to start the cooling mode. The oil and gas are cooled by the first condensing mechanism and the first and second condensing mechanisms and then discharged.

[0031] In this embodiment, this step is the initial operation stage, in which the input oil and gas are preliminarily cooled by the first-stage condensing mechanism, and then the input oil and gas are cryogenically treated by the first and second-stage condensing mechanisms to ensure that the output oil and gas are stable and meet the standards.

[0032] In this embodiment, the first-stage condensing mechanism and the first and second-stage condensing mechanisms are respectively equipped with compressors, which circulate refrigerant through the compressor and transfer the cold energy to the heat exchange tube group of the condenser, so that the oil and gas exchange heat with the low-temperature tube wall when flowing through the condenser; the second-stage condensing mechanism may include a second-stage condenser and a third-stage condenser, and the oil and gas are further deep-cooled to below -65°C through a cascade refrigeration system, so that the low-boiling-point hydrocarbon substances are completely liquefied.

[0033] 200. When the oil and gas temperature at the output end of the first and second condensing mechanisms is lower than a preset cryogenic threshold, the opening and closing states of the first switching valve group and the inlet valve group are adjusted so that the oil and gas output from the first and second condensing mechanisms enter the second and second condensing mechanisms, and the oil and gas pre-cool the second and second condensing mechanisms before being discharged;

[0034] In this embodiment, the preset deep-cold threshold value can be -65°C, and the oil and gas temperature at the output end of the first and second-level condensing mechanism is obtained through the first temperature sensor 81; this step is the pre-cooling trigger stage. When the output oil and gas temperature of the first and second-level condensing mechanisms is lower than the deep-cold threshold value, the low-temperature oil and gas are introduced into the second and second-level condensing mechanism, that is, the channel to be put into use, through the first switching valve group. When the oil and gas flow in the second and second-level condensing mechanism, heat exchange is carried out with the pipeline and condenser, so that the temperature of the second and second-level condensing mechanism gradually drops from room temperature to about -60°C, establishing a low-temperature cold field and completing pre-cooling.

[0035] 300. When the preset switching time is reached, the first-stage condensing mechanism is controlled to stop executing the cooling mode, the opening and closing states of the first switching valve group and the inlet valve group are kept constant, and the second-stage condensing mechanism is controlled to start executing the cooling mode;

[0036] In this embodiment, the preset switching time can be 4 hours to avoid excessive frost on the condenser surface caused by long-term operation of the secondary condensing mechanism; this step is the switching preparation stage. When the preset switching time is reached, the primary condensing mechanism stops refrigeration, and the valve group state remains unchanged. The first and second condensing mechanisms stop supplying cold, and the temperature of the residual oil and gas inside gradually rises. During this process, the frost on the condenser surface can be fully melted, and the temperature difference between the current channel and the channel to be put into use is reduced, which can reduce the impact of the switching process on the compressor pressure, cold supply and other working conditions, and ensure that the new operating channel after switching can quickly enter a stable refrigeration state; if the temperature does not reach above 0°C before switching, the residual ice or frost will block the channel, affecting the subsequent heat exchange efficiency of the channel when used as a pre-cooling or refrigeration channel, and even causing equipment failure; in addition, if the switch is forced when the temperature has not risen to above 0°C, the current channel is still in a low temperature state, and the temperature difference with the channel to be switched is too large, which will cause the oil and gas to have drastic temperature fluctuations at the moment of switching, destroying the stable operation of the refrigeration system.

[0037] In this embodiment, when the first and second-level condensing mechanisms perform defrosting, the oil and gas are cooled and deep-frozen through the second and second-level condensing mechanisms to ensure the oil and gas treatment effect; and the oil and gas are preliminarily cooled by the first and second-level condensing mechanisms, acting as the role of the first-level condensing mechanism, further reducing energy consumption and improving the overall energy efficiency ratio of the oil and gas recovery device; the second and second-level condensing mechanisms are equipped with a compressor, which circulates the refrigerant through the compressor and transfers the cold energy to the heat exchange tube group of the condenser, so that the oil and gas exchange heat with the low-temperature tube wall when flowing through the condenser.

[0038] 400. When the oil and gas temperature at the output end of the first and second condensing mechanisms is ≥ 0°C, the opening and closing states of the inlet valve group, the first switching valve group, and the second switching valve group are adjusted, and the first condensing mechanism is controlled to start the cooling mode. The oil and gas are cooled by the first and second condensing mechanisms and then discharged;

[0039] In this embodiment, this step is the switching operation stage, the first-level condensing mechanism resumes the refrigeration mode, the first-level condensing mechanism and the second-level condensing mechanism cool the oil and gas at the same time. Since the second-level condensing mechanism has been pre-cooled, it can directly enter the deep cooling state. The oil and gas are discharged after cooling, and at the same time prepare to pre-cool the first-level and second-level condensing mechanisms.

[0040] The present application discloses a channel precooling method for a dual-channel oil and gas recovery device, which has the following advantages:

[0041] ① Based on the technical concept of using cold to maintain cold, the system pre-cools the secondary condensing mechanism by utilizing the cooling capacity of low-temperature oil and gas, replacing the traditional pre-cooling method that relies on compressor cooling. This method has the advantage of providing stable cooling capacity to the operating channel. During the switching preparation phase, that is, when the compressor is shut down, the cooled oil and gas is used as the cooling source, reducing the cooling capacity distribution pressure of the refrigeration system and avoiding the problem of insufficient cooling capacity caused by the compressor supplying cooling to two channels at the same time. It can also reduce the cooling capacity consumption of the compressor and improve the overall energy consumption of the dual-channel oil and gas recovery device.

[0042] ② Pre-cooling the secondary condensing mechanism to be put into use by using low-temperature oil and gas can reduce the problem of large temperature fluctuations during switching, ensuring that the oil and gas temperature is always lower than the critical value of the saturation partial pressure of hydrocarbon substances during the switching process, effectively preventing VOCs emissions from exceeding the standard due to temperature rise, and ensuring that the outlet concentration is stable and meets the standard;

[0043] ③ The low-temperature oil and gas not only pre-cools the secondary condensing mechanism to be put into use, ensuring that it can achieve the expected oil and gas processing efficiency during formal operation, but also realizes the secondary separation of gas and liquid through the pre-cooling process, thereby improving the oil and gas recovery efficiency; in addition, the excess cold energy of the low-temperature oil and gas is recovered through pre-cooling, effectively reducing the heating load of the exhaust gas in subsequent treatment, and realizing multiple benefits of cold energy recovery.

[0044] Further, see Figures 1 to 3 The oil and gas are discharged after being cooled by the first-stage condensing mechanism and the second-stage condensing mechanism, and then further comprising:

[0045] 500. When the oil and gas temperature at the output end of the second-stage condensing mechanism is lower than a preset cryogenic threshold, the opening and closing states of the second switching valve group and the inlet valve group are adjusted so that the oil and gas output from the second-stage condensing mechanism enters the first-stage condensing mechanism, and the oil and gas pre-cool the first-stage condensing mechanism before being discharged;

[0046] In this embodiment, the oil and gas temperature at the output end of the second secondary condensing mechanism is obtained by a second temperature sensor 82 .

[0047] 600. When the preset switching time is reached, the first-stage condensing mechanism is controlled to stop executing the cooling mode, the opening and closing states of the second switching valve group and the inlet valve group are kept constant, and the first and second-stage condensing mechanisms are controlled to start executing the cooling mode;

[0048] 700. When the oil and gas temperature at the output end of the second and second-stage condensing mechanisms is ≥0°C, return to adjust the opening and closing states of the inlet valve group, the first switching valve group and the second switching valve group, and control the first and second-stage condensing mechanisms to start executing the refrigeration mode.

[0049] In this embodiment, through closed-loop circulation, the two groups of secondary condensing mechanisms, that is, the two groups of operating channels are always in an orderly state of operation, pre-cooling, and standby, with no window period for switching, effectively improving the stability of continuous operation; and the two groups of secondary condensing mechanisms have symmetrical structures, and the valve group control logic is mirrored, ensuring that the two groups of channels are evenly worn during long-term operation, thereby extending the life of the equipment; the two groups of operating channels are pre-cooled alternately to avoid excessive frost caused by long-term operation of a single channel.

[0050] Further, see Figure 2 and Figure 3 The inlet valve group includes a first inlet valve 41 and a second inlet valve 42, and the first condensing mechanism is connected to the first and second condensing mechanisms and the second second condensing mechanism respectively through the first inlet valve 41 and the second inlet valve 42; the first switching valve group includes a first return valve 52 and a first outlet valve 51, the output end of the first second condensing mechanism is connected to the first outlet valve 51, and is connected to the input end of the second second condensing mechanism through the first return valve 52; the second switching valve group includes a second return valve 62 and a second outlet valve 61, the output end of the second second condensing mechanism is connected to the second outlet valve 61, and is connected to the input end of the first second condensing mechanism through the second return valve 62; the opening and closing states of the adjusting the inlet valve group, the first switching valve group and the second switching valve group, and controlling the first condensing mechanism and the first and second second condensing mechanisms to start the cooling mode, include:

[0051] 101. Control the first inlet valve 41 to be open and the first outlet valve 51 to be open, and the first return air valve 52, the second inlet valve 42, the second outlet valve 61 and the second return air valve 62 to be closed;

[0052] 102. Control the first-stage condensing mechanism and the first and second-stage condensing mechanisms to start executing the cooling mode.

[0053] In this embodiment, the first inlet valve 41 controls the oil and gas to enter the first and second-level condensing mechanisms, and the second inlet valve 42 controls the input oil and gas to enter the second and second-level condensing mechanisms; the first return air valve 52 allows the low-temperature oil and gas of the first and second-level condensing mechanisms to enter the second and second-level condensing mechanisms, and the first outlet valve 51 is used to discharge the oil and gas after deep cooling treatment of the first and second-level condensing mechanisms to the exhaust gas heater 7; the second return air valve 62 allows the low-temperature oil and gas of the second and second-level condensing mechanisms to enter the first and second-level condensing mechanisms, and the second outlet valve 61 is used to discharge the oil and gas after deep cooling treatment of the second and second-level condensing mechanisms to the exhaust gas heater 7; through the combination of the return air valve and the outlet valve, the oil and gas can be seamlessly switched between direct discharge and pre-cooling another channel, which greatly shortens the response time and avoids temperature recovery in the switching gap.

[0054] Further, see Figure 2 and Figure 3 When the oil and gas temperature at the output end of the first and second condensing mechanisms is lower than a preset cryogenic threshold, the opening and closing states of the first switching valve group and the inlet valve group are adjusted so that the oil and gas output from the first and second condensing mechanisms enter the second and second condensing mechanisms, including:

[0055] 201. When the oil and gas temperature at the output end of the first and second condensing mechanisms is lower than a preset cryogenic threshold, the first outlet valve 51 is controlled to be closed, and the first return air valve 52 and the second outlet valve 61 are controlled to be opened;

[0056] 202. The oil and gas outputted from the first and second stage condensing mechanisms enter the second and second stage condensing mechanisms.

[0057] Further, see Figure 2 and Figure 3 When the oil and gas temperature at the output end of the first and second condensing mechanisms is ≥0°C, the opening and closing states of the inlet valve group, the first switching valve group, and the second switching valve group are adjusted, and the first condensing mechanism is controlled to start the cooling mode, including:

[0058] 401. When the oil and gas temperature at the output end of the first and second condensing mechanisms is ≥ 0°C, the compressor is controlled to start running;

[0059] 402. Control the second inlet valve 42 and the second outlet valve 61 to be open, and the first return air valve 52, the first inlet valve 41, the first outlet valve 51 and the second return air valve 62 to be closed;

[0060] 403. Control the first-stage condensing mechanism to start executing the cooling mode.

[0061] Further, see Figure 2 and Figure 3When the oil and gas temperature at the output end of the second secondary condensing mechanism is lower than a preset cryogenic threshold, the opening and closing states of the second switching valve group and the inlet valve group are adjusted so that the oil and gas output from the second secondary condensing mechanism enters the first secondary condensing mechanism, including:

[0062] 501. When the oil and gas temperature at the output end of the second secondary condensing mechanism is lower than the preset cryogenic threshold, the second outlet valve 61 is controlled to be closed, and the second return air valve 62 and the first outlet valve 51 are controlled to be opened;

[0063] 502. The oil and gas outputted from the second and second stage condensing mechanisms enter the first and second stage condensing mechanisms.

[0064] See also Figure 2 and Figure 3 The present invention also provides a dual-channel oil and gas recovery device accordingly, which is used to implement any of the channel pre-cooling methods described above. The dual-channel oil and gas recovery device includes a control device and a first-level condensing mechanism, a first-level condensing mechanism, a second-level condensing mechanism, an inlet valve group, a first switching valve group, a second switching valve group, a first temperature sensor 81 and a second temperature sensor 82, which are electrically connected to the control device respectively; the first-level condensing mechanism is connected to the first-level condensing mechanism and the second-level condensing mechanism respectively through the inlet valve group, and the first-level condensing mechanism and the second-level condensing mechanism are arranged in parallel; the output end of the first-level condensing mechanism is provided with a first temperature sensor 81, and is connected to the input end of the second-level condensing mechanism through the first switching valve group; the output end of the second-level condensing mechanism is provided with a second temperature sensor 82, and is connected to the input end of the first-level condensing mechanism through the second switching valve group.

[0065] The dual-channel oil and gas recovery device disclosed in the present application realizes physical isolation of the operating channel and the pre-cooling channel by arranging the first and second-level condensing mechanisms in parallel, and cooperates with the independently controlled inlet valve group and switching valve group, and realizes the pre-cooling method of using low-temperature oil and gas to pre-cool the channel to be put into use, thereby improving the overall recovery efficiency of the oil and gas recovery device; further, during pre-cooling, the mist-like liquid hydrocarbons in the low-temperature oil and gas will condense due to temperature fluctuations, realizing secondary recovery, significantly improving the recovery rate of liquid hydrocarbons, and thus increasing economic benefits.

[0066] In this embodiment, a first temperature sensor 81 is provided at the output end of the first-stage condensing mechanism, and a second temperature sensor 82 is provided at the output end of the second-stage condensing mechanism to monitor the oil and gas temperature in real time. Combined with the preset deep cooling threshold and the 0°C switching threshold, accurate pre-cooling triggering and channel switching timing judgment are achieved; further, a third temperature sensor 83 is provided at the output end of the first-stage oil and gas condensing mechanism to monitor the temperature of the oil and gas output by the first-stage condensing mechanism in real time, to ensure that the oil and gas have reached a suitable preliminary cooling temperature before entering the second-stage condensing mechanism, thereby further optimizing the pre-cooling effect.

[0067] Further, see Figure 2 and Figure 3 The inlet valve group includes a first inlet valve 41 and a second inlet valve 42, and the first-level condensing mechanism is connected to the first-level condensing mechanism and the second-level condensing mechanism respectively through the first inlet valve 41 and the second inlet valve 42; the first switching valve group includes a first return air valve 52 and a first outlet valve 51, the output end of the first-level condensing mechanism is connected to the first outlet valve 51, and is connected to the input end of the second-level condensing mechanism through the first return air valve 52; the second switching valve group includes a second return air valve 62 and a second outlet valve 61, the output end of the second-level condensing mechanism is connected to the second outlet valve 61, and is connected to the input end of the first-level condensing mechanism through the second return air valve 62.

[0068] In this embodiment, the combination of the first return air valve 52, the second return air valve 62 and the outlet valve realizes the reuse of the cold energy of the low-temperature oil and gas: first, the low-temperature oil and gas in the running channel is directly introduced into the pre-cooling channel through the return air valve, replacing the traditional compressor cooling mode; secondly, through the coordination of the return air valve and the outlet valve, the switching response time is short, avoiding excessive VOCs emissions caused by temperature fluctuations in the switching gap; thirdly, the secondary recovery of the cold energy in the pre-cooling stage is realized, reducing the energy consumption of subsequent heating treatment.

[0069] Further, see Figure 2 and Figure 3 The first-stage condensing mechanism includes a first-stage oil-gas condenser 1, the first-stage second-stage condensing mechanism includes a first-stage second-stage oil-gas condenser 21 and a first-stage third-stage oil-gas condenser 22, and the second-stage second-stage condensing mechanism includes a second-stage second-stage oil-gas condenser 31 and a second-stage third-stage oil-gas condenser 32; the output end of the first-stage oil-gas condenser 1 is connected to the input end of the first-stage second-stage oil-gas condenser 21 and the input end of the second-stage second-stage oil-gas condenser 31 through a first inlet valve 41 and a second inlet valve 42 respectively; the output end of the first return air valve 52 is connected to the input end of the second-stage oil-gas condenser 31 or to the input end of the second-stage third-stage oil-gas condenser 32; the output end of the second return air valve 62 is connected to the input end of the first-stage oil-gas condenser 21 or to the water end of the first-stage third-stage oil-gas condenser 22.

[0070] In this embodiment, when pre-cooling is performed, the cryogenic oil and gas first enter the secondary oil and gas condenser for cooling and then enter the tertiary oil and gas condenser for cooling, thereby realizing pre-cooling of the entire secondary condensing mechanism; compared with the traditional compressor cooling method, full-channel pre-cooling is realized, so that the temperature of the secondary condenser, the tertiary condenser and the intermediate pipeline are all reduced to about -60°C in advance, and the outlet temperature fluctuation after switching can be controlled within 3°C, ensuring that hydrocarbons are always in a low-temperature saturated partial pressure state.

[0071] In other embodiments, the cryogenic oil and gas can directly enter the third-stage oil and gas condenser for pre-cooling, which is suitable for scenarios where the third-stage condenser is the core cooling component or the second-stage condenser has a low risk of frost formation; when processing low-concentration oil and gas, the cooling effect of the second-stage condenser is sufficient. If full-channel pre-cooling is forced, the cryogenic oil and gas will cause some hydrocarbons to condense prematurely in the second-stage condenser due to excess cooling capacity, affecting gas flow; directly pre-cooling the third-stage condenser can reduce the contact between the cryogenic oil and gas and the second-stage condenser, avoid ineffective cooling consumption, and concentrate the cooling capacity of the third-stage condenser on the core cryogenic link.

[0072] Further, see Figure 2 and Figure 3 The dual-channel oil and gas recovery device also includes an exhaust gas heater 7. The output end of the first secondary condensing mechanism is connected to the input end of the exhaust gas heater 7 through the first outlet valve 51; the output end of the second secondary condensing mechanism is connected to the input end of the exhaust gas heater 7 through the second outlet valve 61.

[0073] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all such changes or substitutions should fall within the scope of protection of the present invention.

Claims

1. A channel precooling method for a dual-channel oil and gas recovery device, characterized in that: The dual-channel oil and gas recovery device includes a primary condensing mechanism, a first-secondary condensing mechanism, and a second-secondary condensing mechanism. The primary condensing mechanism is connected to the first-secondary condensing mechanism and the second-secondary condensing mechanism respectively through an inlet valve group. The first-secondary condensing mechanism and the second-secondary condensing mechanism are arranged in parallel. The output end of the first-secondary condensing mechanism is connected to the input end of the second-secondary condensing mechanism through a first switching valve group. The output end of the second-secondary condensing mechanism is connected to the input end of the first-secondary condensing mechanism through a second switching valve group. The channel precooling method includes: Adjust the opening and closing states of the inlet valve group, the first switching valve group, and the second switching valve group, and control the first condensing mechanism and the first and second condensing mechanisms to start the cooling mode. The oil and gas are cooled by the first condensing mechanism and the first and second condensing mechanisms and then discharged; When the oil and gas temperature at the output end of the first and second condensing mechanisms is lower than a preset cryogenic threshold, the opening and closing states of the first switching valve group and the inlet valve group are adjusted so that the oil and gas output from the first and second condensing mechanisms enter the second and second condensing mechanisms, and the oil and gas pre-cool the second and second condensing mechanisms before being discharged; When the preset switching time is reached, the first-stage condensing mechanism is controlled to stop executing the cooling mode, the opening and closing states of the first switching valve group and the inlet valve group are kept constant, and the second-stage condensing mechanism is controlled to start executing the cooling mode; When the oil and gas temperature at the output end of the first and second-stage condensing mechanisms is ≥0℃, the opening and closing states of the inlet valve group, the first switching valve group and the second switching valve group are adjusted, and the first-stage condensing mechanism is controlled to start the cooling mode. The oil and gas are discharged after being cooled by the first-stage condensing mechanism and the second-stage condensing mechanism.

2. The channel precooling method according to claim 1, characterized in that: The oil and gas are discharged after being cooled by the first-stage condensing mechanism and the second-stage condensing mechanism, and then the method further includes: When the oil and gas temperature at the output end of the second-stage condensing mechanism is lower than a preset deep-cold threshold, the opening and closing states of the second switching valve group and the inlet valve group are adjusted so that the oil and gas output from the second-stage condensing mechanism enter the first-stage condensing mechanism, and the oil and gas pre-cool the first-stage condensing mechanism before being discharged; When the preset switching time is reached, the first-stage condensing mechanism is controlled to stop executing the cooling mode, the opening and closing states of the second switching valve group and the inlet valve group are kept constant, and the first and second-stage condensing mechanisms are controlled to start executing the cooling mode; When the oil and gas temperature at the output end of the second and second-stage condensing mechanisms is ≥0°C, the opening and closing states of the inlet valve group, the first switching valve group and the second switching valve group are adjusted, and the first and second-stage condensing mechanisms are controlled to start the refrigeration mode.

3. The channel precooling method according to claim 2, characterized in that: The inlet valve group includes a first inlet valve and a second inlet valve, and the first condensing mechanism is connected to the first and second condensing mechanisms and the second second condensing mechanism respectively through the first inlet valve and the second inlet valve; the first switching valve group includes a first return valve and a first outlet valve, the output end of the first second condensing mechanism is connected to the first outlet valve, and is connected to the input end of the second second condensing mechanism through the first return valve; the second switching valve group includes a second return valve and a second outlet valve, the output end of the second second condensing mechanism is connected to the second outlet valve, and is connected to the input end of the first second condensing mechanism through the second return valve; the opening and closing states of the adjusting the inlet valve group, the first switching valve group and the second switching valve group, and controlling the first condensing mechanism and the first and second second condensing mechanisms to start executing the cooling mode, include: Control the first inlet valve and the first outlet valve to be open, and the first return air valve, the second inlet valve, the second outlet valve and the second return air valve to be closed; The primary condensing mechanism and the first and second condensing mechanisms are controlled to start executing the cooling mode.

4. The channel precooling method according to claim 3, characterized in that: When the oil and gas temperature at the output end of the first and second condensing mechanisms is lower than a preset cryogenic threshold, the opening and closing states of the first switching valve group and the inlet valve group are adjusted so that the oil and gas output from the first and second condensing mechanisms enter the second and second condensing mechanisms, including: When the oil and gas temperature at the output end of the first and second condensing mechanisms is lower than a preset cryogenic threshold, the first outlet valve is controlled to close, and the first return air valve and the second outlet valve are controlled to open; The oil and gas outputted from the first and second stage condensing mechanisms enter the second and second stage condensing mechanisms.

5. The channel precooling method according to claim 4, characterized in that: When the oil and gas temperature at the output end of the first and second condensing mechanisms is ≥0°C, the opening and closing states of the inlet valve group, the first switching valve group, and the second switching valve group are adjusted, and the first condensing mechanism is controlled to start the cooling mode, including: When the oil and gas temperature at the output end of the first and second condensing mechanisms is ≥0°C, the second inlet valve and the second outlet valve are controlled to be open, and the first return air valve, the first inlet valve, the first outlet valve and the second return air valve are closed; Control the first-stage condensing mechanism to start the cooling mode.

6. The channel precooling method according to claim 5, characterized in that: When the oil and gas temperature at the output end of the second secondary condensing mechanism is lower than a preset cryogenic threshold, the opening and closing states of the second switching valve group and the inlet valve group are adjusted so that the oil and gas output from the second secondary condensing mechanism enters the first secondary condensing mechanism, including: When the oil and gas temperature at the output end of the second secondary condensing mechanism is lower than a preset cryogenic threshold, the second outlet valve is controlled to close, and the second return air valve and the first outlet valve are controlled to open; The oil and gas outputted from the second and second stage condensing mechanisms enter the first and second stage condensing mechanisms.

7. A dual-channel oil and gas recovery device, characterized in that: The dual-channel oil and gas recovery device is used to implement the channel pre-cooling method as described in any one of claims 1 to 6, and the dual-channel oil and gas recovery device includes a control device and a first-level condensing mechanism, a first-level and second-level condensing mechanism, a second-level and second-level condensing mechanism, an inlet valve group, a first switching valve group, a second switching valve group, a first temperature sensor and a second temperature sensor, which are electrically connected to the control device respectively; the first-level condensing mechanism is connected to the first-level and second-level condensing mechanism respectively through the inlet valve group, and the first-level condensing mechanism and the second-level condensing mechanism are arranged in parallel; the output end of the first-level condensing mechanism is provided with a first temperature sensor, and is connected to the input end of the second-level condensing mechanism through the first switching valve group; the output end of the second-level condensing mechanism is provided with a second temperature sensor, and is connected to the input end of the first-level condensing mechanism through the second switching valve group.

8. The dual-channel oil and gas recovery device according to claim 7, characterized in that: The inlet valve group includes a first inlet valve and a second inlet valve, and the first-level condensing mechanism is connected to the first-level condensing mechanism and the second-level condensing mechanism respectively through the first inlet valve and the second inlet valve; the first switching valve group includes a first return air valve and a first outlet valve, and the output end of the first-level condensing mechanism is connected to the first outlet valve, and is connected to the input end of the second-level condensing mechanism through the first return air valve; the second switching valve group includes a second return air valve and a second outlet valve, and the output end of the second-level condensing mechanism is connected to the second outlet valve, and is connected to the input end of the first-level condensing mechanism through the second return air valve.

9. The dual-channel oil and gas recovery device according to claim 8, characterized in that: The first-stage condensing mechanism includes a first-stage oil-gas condenser, the first-stage second-stage condensing mechanism includes a first-stage second-stage oil-gas condenser and a first-stage third-stage oil-gas condenser, and the second-stage second-stage condensing mechanism includes a second-stage second-stage oil-gas condenser and a second-stage third-stage oil-gas condenser; the output end of the first-stage oil-gas condenser is connected to the input end of the first-stage second-stage oil-gas condenser and the input end of the second-stage second-stage oil-gas condenser respectively through a first inlet valve and a second inlet valve; The output end of the first return air valve is connected to the input end of the second secondary oil-gas condenser or the input end of the second tertiary oil-gas condenser; the output end of the second return air valve is connected to the input end of the first secondary oil-gas condenser or the water end of the first tertiary oil-gas condenser.

10. The dual-channel oil and gas recovery device according to claim 8, characterized in that: It also includes an exhaust gas heater, wherein the output end of the first secondary condensing mechanism is connected to the input end of the exhaust gas heater through the first outlet valve; the output end of the second secondary condensing mechanism is connected to the input end of the exhaust gas heater through the second outlet valve.

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