Lpg long pipeline venting and recovery apparatus and method

Abstract

The present application belongs to the technical field of LPG long pipeline operation process, and is suitable for station and line valve chamber to handle residual LPG, and specifically relates to a kind of LPG long pipeline venting and recovery equipment, to solve the problems of long time of existing LPG trunk pipeline direct in-situ venting treatment and resource waste caused by direct venting.The present application comprises a recovery device and a burning device, the burning device is connected with the venting pipeline through a first pipeline, and the recovery device is connected with the first pipeline through a first branch line;The venting pipeline is also connected with a nitrogen gas conveying device, which is located upstream of the recovery device and the burning device.The present application is suitable for the venting system design of LPG long pipeline station and valve chamber, which can not only recover a large amount of LPG and reduce LPG waste, but also greatly shorten the trunk pipeline venting treatment time, and the present application is simple in design and easy to operate.

Description

Technical Field

[0001] The present invention belongs to the technical field of treating residual LPG in stations and line valve chambers during the operation of LPG long-distance pipelines, and particularly relates to an LPG long-distance pipeline venting and recovery device. Background Art

[0002] With the steady increase in LPG demand in my country, long-distance LPG pipeline transportation is becoming increasingly common. Because LPG readily vaporizes at low pressure and room temperature, long-distance LPG pipelines are typically transported through high-pressure, buried pipelines. Due to the high saturated vapor pressure of the oil, LPG in the pipeline absorbs heat and partially vaporizes after transportation is stopped, leading to overpressure. Leakage can spread to low-lying areas, potentially exploding when exposed to open flames. Therefore, the LPG must be recovered or vented for combustion.

[0003] Currently, there are no examples of large-scale, long-distance LPG pipelines operating in China. Overseas long-distance LPG transmission projects, whether venting within stations or along pipelines, typically utilize pre-determined vent valve blocks. In practice, venting occurs directly on-site or via mobile flares for incineration. Direct on-site venting fails to meet current environmental protection requirements in my country and poses significant safety risks. If venting is performed directly via mobile flares, the LPG discharge velocity must be limited to prevent unvaporized combustion and the resulting fire rain. Because LPG venting is very slow and the distances between several line valve rooms are long, the venting process can take several days, significantly impacting maintenance schedules. Furthermore, the prolonged use of mobile flares places high demands on supporting utilities (such as nitrogen purge capacity), making this practically impossible in remote locations, such as line valve rooms, where there is no social support. Summary of the Invention

[0004] The present invention provides an LPG long-distance pipeline emptying and recovery device to alleviate the problems of long processing time and waste of resources caused by direct emptying of existing LPG trunk pipelines.

[0005] In order to alleviate the above technical problems, the technical solution provided by the present invention is:

[0006] An LPG long-distance pipeline venting and recovery device includes a recovery device and an incineration device. The incineration device is connected to the venting pipeline through a first pipeline, and the recovery device is connected to the first pipeline through a first branch line. The venting pipeline is also connected to a nitrogen delivery device, which is located upstream of the recovery device and the incineration device.

[0007] Furthermore, an upstream shut-off valve and a downstream shut-off valve are provided on the vent pipeline, the pipeline where the vent pipeline is located downstream of the downstream shut-off valve is the downstream pipeline, the pipeline where the vent pipeline is located upstream of the upstream shut-off valve is the upstream pipeline, and the pipeline where the vent pipeline is located between the upstream shut-off valve and the downstream shut-off valve is the intermediate pipeline.

[0008] Furthermore, the nitrogen delivery device is connected to the intermediate pipeline upstream of the first pipeline input end through a nitrogen pipeline, and a nitrogen injection shut-off valve is provided on the nitrogen pipeline.

[0009] Furthermore, an upstream vent valve and an incineration device shut-off valve located downstream of the upstream vent valve are provided on the first pipeline, the incineration device is located downstream of the incineration device shut-off valve, the input end of the first branch line is connected to the first pipeline between the upstream vent valve and the incineration device shut-off valve, and the input end of the first pipeline is connected to the intermediate pipeline.

[0010] Furthermore, the output end of the first branch line is connected to the input end of the recovery device, the output side of the recovery device is connected to the downstream pipeline through a third pipeline, and a gas injection shut-off valve is provided on the third pipeline.

[0011] Furthermore, the recovery device includes a gas-liquid separation tank and a screw pump for recovering liquid LPG; the gas-liquid separation tank is provided with a liquid inlet, an overflow port and a liquid outlet, and the screw pump is provided with a first inlet and a first outlet, the liquid inlet is connected to the output end of the first branch line, the liquid outlet is connected to the first inlet, and the first outlet is connected to the input end of the third pipeline.

[0012] Furthermore, the recovery device also includes a mobile compressor for recovering gaseous LPG, the mobile compressor is provided with a second inlet and a second outlet, the overflow port is connected to the second inlet, and the second outlet is connected to the input end of the third pipeline.

[0013] Furthermore, the intermediate pipeline is connected to two or more incineration devices, each incineration device is connected to the intermediate pipeline through a different line and only one line is connected to the recovery device.

[0014] A method for emptying and recovering an LPG long-distance pipeline using the above-mentioned LPG long-distance pipeline emptying and recovery equipment is characterized by including a separate processing mode, which includes the following steps:

[0015] Close the upstream shut-off valve, downstream shut-off valve and incinerator shut-off valve, open the upstream vent valve and nitrogen injection shut-off valve, and the gas-liquid two-phase LPG flows into the gas-liquid separation tank;

[0016] Turn on the mobile compressor, screw pump and gas injection shut-off valve to recover the pressurized gaseous LPG and liquid LPG and inject them into the downstream pipeline;

[0017] After the recovery is completed, open the incineration device shut-off valve, close the gas injection shut-off valve, and incinerate the LPG that cannot be recovered.

[0018] Furthermore, a simultaneous processing mode is included, and the simultaneous processing mode includes the following steps:

[0019] Close the upstream shut-off valve and the downstream shut-off valve, and simultaneously open the upstream vent valve, nitrogen injection shut-off valve, gas injection shut-off valve and incineration device shut-off valve, and recover and incinerate the LPG.

[0020] The beneficial effects of the LPG long-distance pipeline venting and recovery equipment of the present invention are analyzed as follows:

[0021] The equipment includes a recovery device and an incineration device. The incineration device is connected to the venting pipeline through a first pipeline, and the recovery device is connected to the first pipeline through a first branch line. The venting pipeline is also connected to a nitrogen conveying device, which is located upstream of the recovery device and the incineration device.

[0022] When the LPG pipeline stops transmitting, nitrogen from the nitrogen delivery device purges the venting pipeline, and the gas-liquid LPG enters the recovery device for recovery. Any gas-liquid LPG that cannot be recovered enters the incineration device for incineration. This invention is suitable for the design of venting systems for long-distance LPG pipeline stations and valve chambers. It not only recovers large quantities of LPG, reducing LPG waste, but also significantly shortens the trunk pipeline venting process time. The invention is simple in design and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in related technologies, the following briefly introduces the drawings required for use in the specific embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 A schematic diagram of a process flow of an LPG long-distance pipeline venting and recovery device provided in an embodiment of the present invention;

[0025] Figure 2 A schematic structural diagram of a recovery device provided in an embodiment of the present invention;

[0026] Figure 3 A schematic structural diagram of an incineration device provided in an embodiment of the present invention.

[0027] icon:

[0028] 100-incineration device; 110-incineration head assembly; 120-incineration pit assembly; 150-incineration device shut-off valve; 200-recovery device; 210-mobile compressor; 220-screw pump; 230-gas-liquid separation tank; 211-gas recovery branch shut-off valve, 221-liquid recovery branch shut-off valve; 300-intermediate pipeline; 400-upstream pipeline; 410-upstream shut-off valve; 500-downstream pipeline; 510-downstream shut-off valve Valve; 600-first pipeline; 610-upstream vent valve; 620-first branch line; 700-nitrogen pipeline; 710-nitrogen injection shut-off valve; 800-second pipeline; 810-downstream vent valve; 900-third pipeline; 910-gas injection shut-off valve; 001-liquid inlet; 002-overflow port; 003-liquid outlet; 004-first inlet; 005-first outlet; 006-second inlet; 007-second outlet. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do 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 limiting the present invention. In addition, the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. Physical quantities in formulas, unless separately marked, should be understood as basic quantities of the International System of Units, or derived quantities derived from basic quantities through mathematical operations such as multiplication, division, differentiation or integration.

[0031] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0032] With the steady increase in demand for LPG (liquefied petroleum gas) in my country, long-distance pipeline transportation of LPG is becoming increasingly common. Because LPG readily vaporizes at low pressure and room temperature, long-distance LPG pipelines typically utilize high-pressure, buried pipelines. Due to the high saturated vapor pressure of the oil, LPG in the pipeline absorbs heat and partially vaporizes after transportation is stopped, leading to overpressure. Leakage can spread to low-lying areas, potentially exploding if exposed to open flames. Therefore, the LPG must be recovered or vented for combustion.

[0033] Currently, there are no examples of large-scale, long-distance LPG pipelines operating in China. Overseas long-distance LPG transmission projects, whether venting within stations or along pipelines, typically utilize pre-determined vent valve blocks. In practice, venting occurs directly on-site or via mobile flares for incineration. Direct on-site venting fails to meet current environmental protection requirements in my country and poses significant safety risks. If venting is performed directly via mobile flares, the LPG discharge velocity must be limited to prevent unvaporized combustion and the resulting fire rain. Because LPG venting is very slow and the distances between several line valve rooms are long, the venting process can take several days, significantly impacting maintenance schedules. Furthermore, the prolonged use of mobile flares places high demands on supporting utilities (such as nitrogen purge capacity), making this practically impossible in remote locations, such as line valve rooms, where there is no social support.

[0034] In view of this, the present invention provides an LPG long-distance pipeline emptying and recovery equipment, please refer to Figure 1 The equipment includes a recovery device 200 and an incineration device 100. The incineration device 100 is connected to the venting pipeline through a first pipeline 600, and the recovery device 200 is connected to the first pipeline 600 through a first branch line 620; the venting pipeline is also connected to a nitrogen conveying device, which is located upstream of the recovery device 200 and the incineration device 100.

[0035] When LPG pipeline transportation is stopped, nitrogen output from the nitrogen delivery device purges the venting pipeline, and the gas-liquid two-phase LPG enters the recovery device 200 for recovery. The gas-liquid two-phase LPG that cannot be recovered enters the incineration device 100 for incineration. The present invention is suitable for the design of venting systems for long-distance LPG pipeline stations and valve rooms. It not only recovers large amounts of LPG and reduces LPG waste, but also significantly shortens the trunk pipeline venting process time. The invention is simple in design and easy to operate.

[0036] In an optional solution of this embodiment, an upstream block valve 410 and a downstream block valve 510 are provided on the vent line. The portion of the vent line downstream of the downstream block valve 510 is referred to as the downstream line 500, the portion of the vent line upstream of the upstream block valve 410 is referred to as the upstream line 400, and the portion of the vent line between the upstream block valve 410 and the downstream block valve 510 is referred to as the intermediate line 300. The upstream block valve 410 and the downstream block valve 510 are used to shut off the pipeline requiring maintenance. The LPG in the intermediate line 300 obtained after the shutoff is recovered or vented and combusted.

[0037] In an alternative embodiment of this embodiment, a nitrogen delivery device is connected to the intermediate pipeline 300 upstream of the input end of the first pipeline 600 via a nitrogen pipeline 700. A nitrogen injection shutoff valve 710 is provided on the nitrogen pipeline 700. The nitrogen pressure within the nitrogen pipeline 700 is greater than the saturated vapor pressure of LPG at ground temperature. The pressurized nitrogen purges the LPG liquid in the intermediate pipeline 300, thereby mitigating the environmental impact of on-site venting and shortening the time required to clear the main pipeline.

[0038] In an alternative embodiment of this embodiment, the first pipeline 600 is provided with an upstream vent valve 610 and an incinerator shut-off valve 150 located downstream of the upstream vent valve 610. The incinerator 100 is located downstream of the incinerator shut-off valve 150. The input end of the first branch line 620 is connected to the first pipeline 600 between the upstream vent valve 610 and the incinerator shut-off valve 150. The input end of the first pipeline 600 is also connected to the intermediate pipeline 300. When the LPG in the intermediate pipeline 300 needs to be processed, the upstream shut-off valve 410 and the downstream shut-off valve 510 are first closed, and the upstream vent valve 610 and the incinerator shut-off valve 150 are opened. The LPG in the intermediate pipeline 300 enters the first pipeline 600. Then, a portion of the LPG flows from the first pipeline 600 into the first branch line 620, while the remaining portion enters the incinerator 100 for incineration.

[0039] In an alternative embodiment of this embodiment, the output end of first branch line 620 is connected to the input end of recovery device 200. The output side of recovery device 200 is connected to downstream pipeline 500 via third pipeline 900, and third pipeline 900 is provided with a gas injection shutoff valve 910. When recovering LPG in intermediate pipeline 300, gas injection shutoff valve 910 is opened, and LPG entering first branch line 620 flows into recovery device 200. After recovery, LPG enters downstream pipeline 500 through third pipeline 900 for recycling. After recovery is completed, gas injection shutoff valve 910 can be closed.

[0040] For the optional solutions of this embodiment, please refer to Figure 2The recovery device 200 includes a gas-liquid separation tank 230 and a screw pump 220 for recovering liquid LPG; the gas-liquid separation tank 230 is provided with a liquid inlet 001, an overflow port 002 and a liquid outlet 003, and the screw pump 220 is provided with a first inlet 004 and a first outlet 005, the liquid inlet 001 is connected to the output end of the first branch line 620, the liquid outlet 003 is connected to the first inlet 004, and the first outlet 005 is connected to the input end of the third pipeline 900 through a connecting pipeline provided with a liquid recovery branch shut-off valve 221. The LPG entering the first branch line 620 enters the gas-liquid separation tank 230 from the liquid inlet 001, and the gaseous LPG and liquid-phase LPG are separated in the gas-liquid separation tank 230. The gaseous LPG is discharged from the overflow port 002, and the liquid-phase LPG is discharged from the liquid outlet 003, and then enters the screw pump 220 through the first inlet 004. After the screw pump 220 pressurizes and recovers the liquid-phase LPG, it flows out of the screw pump 220 through the first outlet 005, and then enters the third pipeline 900 through the connecting pipeline.

[0041] In an optional solution of this embodiment, recovery device 200 further includes a mobile compressor 210 for recovering gaseous LPG. Mobile compressor 210 is provided with a second inlet 006 and a second outlet 007. Overflow port 002 is connected to second inlet 006, and second outlet 007 is connected to the input end of third pipeline 900 via a connecting pipeline equipped with a gas recovery branch shut-off valve 211. The gaseous LPG separated by gas-liquid separator 230 is discharged through overflow port 002 and then enters mobile compressor 210 through second inlet 006. After being recovered by mobile compressor 210, the gaseous LPG flows out of mobile compressor 210 through second outlet 007 and then enters third pipeline 900 through a connecting pipeline.

[0042] Furthermore, the recovery device 200 in this embodiment is configured to be skid-mounted, and the skid-mounted recovery device 200 is set on a mobile cart. When different trunk pipelines are emptied, the recovery device 200 can be directly moved to the work site by driving the mobile cart through a tractor, which is convenient and quick.

[0043] In an optional solution of this embodiment, the intermediate pipeline 300 connects two or more incinerators 100. Each incinerator 100 is connected to the intermediate pipeline 300 via a different line, and only one line is connected to the recovery device 200. Multiple incinerators 100 can operate simultaneously, significantly improving the incineration efficiency of LPG and saving pipeline venting time.

[0044] Preferably, in this embodiment, the intermediate pipeline 300 is connected to two incineration devices 100, one of which is connected to the intermediate pipeline 300 via a first pipeline 600, and the other is connected to the intermediate pipeline 300 via a second pipeline 800. The second pipeline 800 is provided with a downstream vent valve 810. The two incineration devices 100 are simple to operate and can be used separately or simultaneously. When the two incineration devices 100 are in operation simultaneously, the incineration efficiency can be greatly improved.

[0045] For details on the structure and shape of the incinerator 100, please refer to Figure 3 , the details are as follows:

[0046] The incinerator 100, consisting of an incinerator head assembly 110 and an incinerator pit assembly 120, is a permanent device capable of incinerating both liquids and gases, regardless of the type of fluid. The incinerator 100 is permanently located outside the valve room or station enclosure where incineration is required. Thermal insulation barriers can be installed around the incinerator 100 to minimize the impact of thermal radiation from LPG combustion on the surrounding area.

[0047] The specific process of LPG recovery and incineration in the venting pipeline is as follows:

[0048] When the LPG in the venting pipeline needs to be processed, the upstream shut-off valve 410 and the downstream shut-off valve 510 are closed, and the nitrogen injection shut-off valve 710, the incineration device shut-off valve 150, the gas injection shut-off valve 910, the gas recovery branch shut-off valve 211, the liquid recovery branch shut-off valve 221, the upstream venting valve 610 and the downstream venting valve 810 are opened. The LPG in the intermediate pipeline 300 enters the first pipeline 600 and the second pipeline 800 under the purge of pressurized nitrogen. The LPG in the first pipeline 600 enters the gas-liquid separation tank 230 and is separated. The gaseous LPG is discharged from overflow port 002 of gas-liquid separator tank 230 and then enters mobile compressor 210 through second inlet 006. The pressurized LPG enters third pipeline 900 through a connecting pipeline and then enters downstream pipeline 500. The separated liquid LPG is discharged from overflow port 002 of gas-liquid separator tank 230 and then enters screw pump 220 through first inlet 004. The pressurized liquid LPG is then re-gasified into gaseous LPG and then enters third pipeline 900 through a connecting pipeline and then enters downstream pipeline 500. Unrecoverable gas-liquid LPG enters incinerator 100 for incineration.

[0049] The beneficial effects of LPG long-distance pipeline venting and recovery equipment are as follows:

[0050] 1. After being processed by the recovery device 200, most of the LPG can be recovered, which not only reduces economic losses but also avoids environmental pollution caused by the combustion of large amounts of LPG;

[0051] 2. The recovery device 200 is mobile, which can reduce the permanent land acquisition for fixed facilities. All valve rooms and stations along the entire line can share the same recovery device 200, reducing investment;

[0052] 3. Recovery and incineration can be carried out simultaneously, greatly improving operational efficiency and shortening the time for pipeline LPG venting.

[0053] Example 2

[0054] A method for emptying and recovering an LPG long-distance pipeline using the above-mentioned LPG long-distance pipeline emptying and recovery equipment is characterized by including a separate processing mode, which includes the following steps:

[0055] S1. Close the upstream shutoff valve 410, downstream shutoff valve 510, and incinerator shutoff valve 150, open the upstream vent valve 610 and nitrogen injection shutoff valve 710, and allow the gas-liquid two-phase LPG to flow into the gas-liquid separation tank 230;

[0056] S2. When the pressure in the gas-liquid separation tank 230 reaches equilibrium with the pressure in the trunk pipeline, the mobile compressor 210, the screw pump 220, the gas recovery branch shutoff valve 211, the liquid recovery branch shutoff valve 221, and the gas injection shutoff valve 910 are opened, and the pressurized gaseous and liquid LPG enter the downstream pipeline;

[0057] S3. After the recovery is completed, the incineration device shut-off valve 150 and the downstream vent valve 810 are opened, and the gas injection shut-off valve 910 is closed to incinerate the LPG that cannot be recovered.

[0058] The optional solution of this embodiment includes a simultaneous processing mode, which includes the following steps:

[0059] S1. Calculation: Estimate the volume of LPG recovered and incinerated based on the formula "pipe capacity of intermediate pipeline 300 = volume of LPG to be processed = volume of LPG recovered by recovery device 200 + volume of LPG incinerated by incineration device 100" by combining the efficiency of recovery device 200 and incineration device 100 and the preset processing time.

[0060] S2. Close the upstream shutoff valve 410 and the downstream shutoff valve 510, and open the upstream vent valve 610, the downstream vent valve 810, the nitrogen injection shutoff valve 710, the gas injection shutoff valve 910, the gas recovery branch shutoff valve 211, the liquid recovery branch shutoff valve 221, and the incineration device shutoff valve 150 to simultaneously recover and incinerate the gas-liquid LPG.

[0061] S3. When the amount of recovered LPG reaches the estimated volume of recovered LPG, the gas injection shutoff valve 910, the gas recovery branch shutoff valve 211 and the liquid recovery branch shutoff valve 221 are closed to continue incinerating the unrecoverable LPG.

[0062] In combination with Example 1 and Example 2, the beneficial effects of the method for emptying and recovering an LPG long-distance pipeline are as follows:

[0063]

[0064] Note: 1) The pipeline size of the intermediate pipeline 300 is D273mm×8.7mm (pipeline diameter×wall thickness). Multiplying this by the length of 16km, the total pipe capacity of the intermediate pipeline 300 is converted to 821m 3 ;

[0065] 2) Screw pump 220 recovers liquid LPG: The total recovery time is about 38 hours, and the total recovered liquid LPG is about 514m 3 ;

[0066] 3) Mobile compressor 210 recovers gaseous LPG: The total recovery time is about 48 hours, and the total recovered gaseous LPG is about 4.5×10 4 Nm 3 , equivalent to the volume of liquid LPG under supercharging conditions is 95.2 m 3 ;

[0067] 4) The remaining LPG that cannot be recovered will be gasified and incinerated. The total volume of liquid LPG recovered is 609.2m3 3 , the recovery efficiency is 74.2%.

[0068] 1. As shown in the table above, after treatment, up to 74.2% of LPG can be recovered. Compared with the zero recovery of existing technologies, this can significantly reduce economic losses and avoid the environmental pollution caused by the combustion of large amounts of LPG;

[0069] 2. Shorten the time for LPG venting and incineration in the pipeline. The operation time of simultaneous recovery and incineration can be shortened by 38% compared with the existing technology;

[0070] 3. The recovery device 200 is mobile, reducing the permanent land acquisition for fixed facilities. All valve rooms and stations along the entire line can share the same recovery device 200, reducing investment.

[0071] 4. It can improve the safety of venting operations, greatly reduce project investment and accelerate construction progress.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An LPG long-distance pipeline venting and recovery device, characterized by: It comprises a recovery device (200) and an incineration device (100), wherein the incineration device (100) is connected to a venting pipeline via a first pipeline (600), and the recovery device (200) is connected to the first pipeline (600) via a first branch line (620); The venting pipeline is further connected to a nitrogen delivery device, the nitrogen delivery device is located upstream of the recovery device (200) and the incineration device (100), and the nitrogen delivery device is connected to the venting pipeline upstream of the input end of the first pipeline (600); An upstream shutoff valve (410) and a downstream shutoff valve (510) are provided on the venting pipeline, and the pipeline between the upstream shutoff valve (410) and the downstream shutoff valve (510) is referred to as the intermediate pipeline (300); The first pipeline (600) is provided with an upstream vent valve (610) and an incineration device shut-off valve (150) located downstream of the upstream vent valve (610); The intermediate pipeline (300) is connected to two incineration devices (100), wherein one of the incineration devices (100) is connected to the intermediate pipeline (300) via the first pipeline (600), and the other incineration device (100) is connected to the intermediate pipeline (300) via a second pipeline (800), and a downstream vent valve (810) is provided on the second pipeline (800).

2. The LPG long-distance pipeline emptying and recovery equipment according to claim 1 is characterized in that: The nitrogen delivery device is connected to the intermediate pipeline (300) upstream of the input end of the first pipeline (600) via a nitrogen pipeline (700), and a nitrogen injection shutoff valve (710) is provided on the nitrogen pipeline (700).

3. The LPG long-distance pipeline emptying and recovery equipment according to claim 2 is characterized in that: The incineration device (100) is located downstream of the incineration device shut-off valve (150), the input end of the first branch line (620) is connected to the first pipeline (600) between the upstream vent valve (610) and the incineration device shut-off valve (150), and the input end of the first pipeline (600) is connected to the intermediate pipeline (300).

4. The LPG long-distance pipeline emptying and recovery equipment according to claim 3 is characterized in that: The pipeline of the vent line located downstream of the downstream shut-off valve (510) is referred to as the downstream pipeline (500), and the pipeline of the vent line located upstream of the upstream shut-off valve (410) is referred to as the upstream pipeline (400); The output end of the first branch line (620) is connected to the input end of the recovery device (200), and the output side of the recovery device (200) is connected to the downstream pipeline (500) via a third pipeline (900), and a gas injection shutoff valve (910) is provided on the third pipeline (900).

5. The LPG long-distance pipeline emptying and recovery equipment according to claim 4 is characterized in that: The recovery device (200) includes a gas-liquid separation tank (230) and a screw pump (220) for recovering liquid-phase LPG; The gas-liquid separation tank (230) is provided with a liquid inlet (001), an overflow port (002) and a liquid outlet (003); the screw pump (220) is provided with a first inlet (004) and a first outlet (005); the liquid inlet (001) is connected to the output end of the first branch line (620); the liquid outlet (003) is connected to the first inlet (004); and the first outlet (005) is connected to the input end of the third pipeline (900).

6. The LPG long-distance pipeline emptying and recovery equipment according to claim 5, characterized in that: The recovery device (200) further comprises a mobile compressor (210) for recovering gaseous LPG, wherein the mobile compressor (210) is provided with a second inlet (006) and a second outlet (007), the overflow port (002) is connected to the second inlet (006), and the second outlet (007) is connected to the input end of the third pipeline (900).

7. A method for emptying and recovering an LPG long-distance pipeline using the LPG long-distance pipeline emptying and recovery equipment according to claim 6, characterized in that: A separate processing mode is included, wherein the separate processing mode includes the following steps: The upstream shutoff valve (410), the downstream shutoff valve (510), and the incineration device shutoff valve (150) are closed, and the upstream vent valve (610) and the nitrogen injection shutoff valve (710) are opened, so that the gas-liquid two-phase LPG flows into the gas-liquid separation tank (230); Opening the mobile compressor (210), the screw pump (220), and the gas injection shutoff valve (910), recovering the pressurized gaseous LPG and liquid LPG, and injecting them into the downstream pipeline (500); After the recovery is completed, the incineration device shut-off valve (150) is opened, and the gas injection shut-off valve (910) is closed to incinerate the LPG that cannot be recovered.

8. The method for emptying and recovering LPG long-distance pipeline according to claim 7, characterized in that: Including a simultaneous processing mode, the simultaneous processing mode includes the following steps: The upstream shutoff valve (410) and the downstream shutoff valve (510) are closed, and the upstream vent valve (610), the nitrogen injection shutoff valve (710), the gas injection shutoff valve (910) and the incineration device shutoff valve (150) are opened simultaneously, and LPG is recovered and incinerated at the same time.

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