Device and method for sequentially injecting liquid ammonia and oil into conveying pipeline

Abstract

The invention discloses a device and a method for sequentially injecting liquid ammonia and an oil product into a conveying pipeline, and relates to the technical field of fuel transportation. The device comprises a liquid ammonia storage tank and an oil product storage tank, the liquid ammonia storage tank is communicated with a sequential conveying main pipeline through a liquid ammonia conveying pipeline, and a liquid feeding pump, a liquid conveying main pump and a liquid conveying valve are sequentially arranged on the liquid ammonia conveying pipeline; the liquid ammonia storage tank is additionally communicated with the liquid ammonia conveying pipeline between the liquid conveying main pump and the liquid conveying valve through a cold insulation backflow pipeline, and a backflow valve is arranged on the cold insulation backflow pipeline; the oil product storage tank is communicated with the sequential conveying main pipeline through an oil product conveying pipeline, and an oil conveying main pump and an oil conveying valve are sequentially arranged on the oil product conveying pipeline. The liquid conveying main pump can provide pressure higher than ammonia saturated vapor pressure under the normal temperature condition, and pipeline damage is avoided. When the liquid ammonia stops being injected into the sequential conveying main pipeline, the ammonia in the liquid ammonia conveying pipeline is kept in a liquid phase state through cold insulation circulation, and unstable pressure caused by vaporization of the liquid ammonia retained in the liquid ammonia conveying pipeline is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of fuel transportation, and in particular to a device and method for sequentially injecting liquid ammonia and oil products into a transportation pipeline. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] As an extension of the hydrogen industry, liquid ammonia is considered a new type of low-carbon fuel. As a fuel, liquid ammonia can be transported with extremely high efficiency through existing oil pipeline facilities. The boiling point of liquid ammonia at normal pressure is -33.5°C. With the help of low-temperature and normal pressure storage tanks, large-scale storage can be achieved at conditions below -33.5°C. Gasoline, diesel and other finished oils (oil products) obtained by refineries are usually stored at normal temperature and pressure, and the storage temperature is 0-50°C. Sequential transportation (also known as alternating transportation) refers to the alternating transportation of two or more media in a set sequence in the same section of the pipeline. It can be applied to the transportation of liquid ammonia and oil products in existing oil pipeline facilities. However, the sequential transportation of liquid ammonia and oil products will face many problems, including:

[0004] (1) The temperature of liquid ammonia is relatively low. If there is a large temperature difference between it and the transported finished oil, the alternating hot and cold phenomena in the pipeline will cause stress damage. If the temperature of the liquid ammonia entering the buried pipeline is too low, it is easy to cause the soil around the buried pipeline to frost and expand, resulting in pipeline damage.

[0005] (2) When switching between processes with different media, the temperature of low-temperature liquid ammonia increases after mixing with high-temperature oil products, causing the saturated vapor pressure to increase and the liquid ammonia vaporization to threaten pipeline safety. When the main pipeline is used to transport oil products in sequence, the liquid ammonia injection pipeline is in a stopped state. Due to the absorption of heat from the surrounding environment, the temperature of the liquid ammonia in the pipeline will continue to rise, and liquid ammonia vaporization may occur, threatening pipeline safety. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a device and method for sequentially injecting liquid ammonia and oil products into a transportation pipeline. By setting up multiple booster pumps and cold-keeping circulation pipelines, the injection process from a low-temperature and normal-pressure liquid ammonia storage tank to a sequential transportation main pipeline is realized.

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

[0008] A first aspect of the present invention provides a device for sequentially injecting liquid ammonia and oil products into a delivery pipeline, comprising: a liquid ammonia storage tank and an oil product storage tank, wherein the liquid ammonia storage tank is connected to a sequential delivery main pipeline via a liquid ammonia delivery pipeline, and a liquid feed pump, a liquid infusion main pump and a liquid infusion valve are sequentially arranged on the liquid ammonia delivery pipeline; the liquid ammonia storage tank is also connected to the liquid ammonia delivery pipeline between the liquid infusion main pump and the liquid infusion valve via a cold-keeping return pipeline, and a return valve is arranged on the cold-keeping return pipeline;

[0009] The oil storage tank is connected to the main oil delivery pipeline via an oil delivery pipeline, and an oil delivery main pump and an oil delivery valve are sequentially arranged on the oil delivery pipeline.

[0010] The second aspect of the present invention provides a method for sequentially injecting liquid ammonia and oil products into a delivery pipeline based on the above-mentioned device for sequentially injecting liquid ammonia and oil products into a delivery pipeline, comprising the following process:

[0011] S1. The liquid ammonia transported by the liquid ammonia storage tank is pressurized by the liquid pump to a level above the ammonia saturated vapor pressure corresponding to the highest temperature of the liquid ammonia transport pipeline upstream of the infusion main pump. The infusion main pump provides the operating pressure of the sequential transport main pipeline to maintain liquid transport to the sequential transport main pipeline. At the same time, the reflux valve is in a closed state, so that the liquid ammonia pressure in the cold-keeping reflux pipeline is above the ammonia saturated vapor pressure of the cold-keeping reflux pipeline temperature, and the oil delivery valve is closed;

[0012] S2. The oil products transported from the oil storage tank enter the sequential transportation main pipeline through the oil delivery main pump and the oil delivery valve; the reflux valve is in the open state, the infusion valve is in the closed state, the infusion main pump is stopped, and the liquid feed pump is running, so that the liquid ammonia in the liquid ammonia delivery pipeline flows back to the liquid ammonia storage tank through the cold-insulated reflux pipeline.

[0013] The beneficial effects of the present invention are as follows:

[0014] 1. The present invention sets the liquid ammonia injection point downstream of the main infusion pump. During the process of injecting liquid ammonia into the sequential delivery main pipeline, the main purpose of the main infusion pump is to provide the operating pressure of the sequential delivery main pipeline when the liquid ammonia is injected into the sequential delivery main pipeline. This pressure is higher than the saturated vapor pressure of ammonia under normal temperature conditions. Therefore, when the liquid ammonia contacts the oil interface, even if the temperature rises rapidly to normal temperature, it will not vaporize, thereby avoiding damage to the pipeline. When the liquid ammonia stops being injected into the sequential delivery main pipeline, the heating unit and the main infusion pump are stopped, and the ammonia in the liquid ammonia delivery pipeline is maintained in a liquid phase through a cold-keeping reflux cycle to avoid the vaporization of the retained liquid ammonia causing pressure instability.

[0015] 2. The liquid ammonia delivery pipeline of the present invention is provided with a heating device, and the low-temperature liquid ammonia can be heated during the process of liquid ammonia being injected into the sequential delivery main pipeline, so as to avoid problems such as thermal stress damage to the pipeline body and frost heave of soil around the pipeline caused by the medium temperature entering the sequential delivery main pipeline being too low. The liquid ammonia delivery pipeline of the present invention is provided with a sealing valve. If the main infusion pump is far away from the sequential delivery main pipeline, when the liquid ammonia stops being injected into the sequential delivery main pipeline and the cost of cold preservation circulation is high, the sealing valve is closed to control the pipe section from the main infusion pump to the injection point to be in a high-pressure state, thereby ensuring that the ammonia is in a liquid phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0017] In order to show the positions of various parts, the distances or sizes between them are exaggerated in the figure, and the schematic diagram is for illustration only.

[0018] Figure 1 It is a schematic diagram of the connection relationship of the device for sequentially injecting liquid ammonia and oil products into the delivery pipeline in Example 1.

[0019] Figure 2 It is a schematic diagram of the partial connection relationship of the device for sequentially injecting liquid ammonia and oil products into the delivery pipeline in Example 2.

[0020] Among them, 1. Liquid ammonia storage tank; 2. Reflux valve; 3. Cold-insulated reflux pipeline; 4. Liquid feeding pump; 5. Heating device; 6. Infusion main pump; 7. Branch point; 8. Sealing valve; 9. Ammonia injection pipeline; 10. Infusion valve; 11. Liquid ammonia injection point; 12. Sequential transportation main pipeline; 13. Oil delivery valve; 14. Oil delivery main pump; 15. Oil storage tank. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0022] A device for sequentially injecting liquid ammonia and oil products into a delivery pipeline, comprising: a liquid ammonia storage tank and an oil product storage tank, wherein the liquid ammonia storage tank is connected to a sequential delivery main pipeline through a liquid ammonia delivery pipeline, and a liquid feed pump, a liquid infusion main pump and a liquid infusion valve are sequentially arranged on the liquid ammonia delivery pipeline; the liquid ammonia storage tank is also connected to the liquid ammonia delivery pipeline between the liquid infusion main pump and the liquid infusion valve through a cold-keeping return pipeline, and a return valve is arranged on the cold-keeping return pipeline;

[0023] The oil storage tank is connected to the main oil delivery pipeline via an oil delivery pipeline, and an oil delivery main pump and an oil delivery valve are sequentially arranged on the oil delivery pipeline.

[0024] In the above settings, the infusion main pump provides the operating pressure of the sequential delivery main pipeline when liquid ammonia is injected into the sequential delivery main pipeline (in engineering, this pressure is definitely higher than the saturated vapor pressure of ammonia at normal temperature). Therefore, when liquid ammonia enters the sequential delivery main pipeline or contacts the oil interface, it will not vaporize even if the temperature rises rapidly to normal temperature, thereby avoiding damage to the pipeline; when the infusion valve is closed and the injection of liquid ammonia into the sequential delivery main pipeline is stopped, the heating unit and the infusion main pump are also stopped, and the reflux valve is opened. The circulation power is provided by the liquid pump, and the cold preservation circulation maintains the ammonia in the liquid ammonia delivery pipeline in a liquid phase, thereby avoiding the vaporization of the retained liquid ammonia and causing pressure instability.

[0025] Optionally, a heating device is provided on the liquid ammonia delivery pipeline between the liquid feed pump and the infusion main pump; the function of the heating device is to heat the liquid ammonia flowing out of the low-temperature and normal-pressure storage tank to avoid the liquid ammonia entering the sequential delivery main pipeline being too low in temperature, causing frost heaving of the soil around the buried pipeline and affecting the safety of the pipeline body structure; when the temperature of the liquid ammonia pipeline downstream of the infusion main pump is lower than 0°C when entering the buried section of the pipeline, a heating device needs to be provided, and the outlet temperature of the heating device raises the temperature of the liquid ammonia to no less than 0°C when entering the buried section of the pipeline.

[0026] Optionally, the heating device is close to the infusion main pump to avoid excessive pressure drop caused by the long pipe section between the heating device and the infusion main pump, which may cause the pressure at the inlet of the infusion main pump to be lower than the saturated vapor pressure of ammonia, thereby avoiding the gasification of liquid ammonia.

[0027] Optionally, the main infusion pump is close to the cold-insulating reflux pipeline, so that the heated liquid ammonia in the cold-insulating pipeline from the heating unit is as small as possible. When the heated liquid ammonia stops being injected into the main pipeline, the heating device stops operating and the cold-insulating pipeline resumes flow, the low-temperature liquid ammonia can quickly replace the heated liquid ammonia.

[0028] Optionally, when the infusion main pump is far away from the sequential delivery main pipeline, a sealing valve is arranged between the infusion main pump and the infusion valve, and the cold preservation reflux pipeline is connected between the infusion main pump and the sealing valve, so that the pipeline between the sealing valve and the infusion valve can maintain a closed state and not participate in the cold preservation reflux process.

[0029] Optionally, the liquid feed pump is close to the liquid ammonia storage tank, or installed inside the liquid ammonia storage tank; thereby avoiding vaporization caused by the liquid ammonia upstream of the liquid feed pump absorbing heat from the external environment and increasing temperature; when a heating device is installed, the outlet pressure of the liquid feed pump is higher than the saturated vapor pressure of ammonia corresponding to the outlet temperature of the heating device.

[0030] Optionally, the reflux valve is close to the liquid ammonia storage tank or installed inside the liquid ammonia storage tank. During the process of liquid ammonia being injected into the sequential transport main pipeline, the reflux valve controls the pressure in the upstream cold-insulated reflux line to be above the saturated vapor pressure of ammonia at the corresponding temperature by adjusting its opening. Specifically, the smaller the opening of the reflux valve, the smaller its flow area, and the closer the pressure upstream is to the output end pressure of the infusion main pump, thereby controlling the pressure in the cold-insulated reflux line to be above the saturated vapor pressure of ammonia at the corresponding temperature.

[0031] Based on the above-mentioned device for sequentially injecting liquid ammonia and oil products into a delivery pipeline, the method for sequentially injecting liquid ammonia and oil products into a delivery pipeline includes the following process:

[0032] S1. The liquid ammonia transported by the liquid ammonia storage tank is pressurized to a level above the saturated vapor pressure corresponding to the temperature of the liquid ammonia delivery pipeline by the liquid feed pump. The operating pressure of the sequential delivery main pipeline is provided by the liquid delivery main pump to maintain liquid delivery to the sequential delivery main pipeline. At the same time, the reflux valve is in a closed state, so that the liquid ammonia pressure in the cold-keeping reflux pipeline is above the saturated vapor pressure of the cold-keeping reflux pipeline temperature, and the oil delivery valve is closed;

[0033] S2. The oil products transported from the oil storage tank enter the sequential transportation main pipeline through the oil delivery main pump and the oil delivery valve; the reflux valve is in the open state, the infusion valve is in the closed state, the infusion main pump is stopped, and the liquid feed pump is running to make the liquid ammonia in the liquid ammonia delivery pipeline flow back to the liquid ammonia storage tank through the cold-insulated reflux pipeline.

[0034] In the above process, the infusion main pump can prevent the liquid ammonia entering the sequential delivery main pipeline from being vaporized, the liquid feeding pump can prevent the liquid ammonia in the liquid ammonia delivery pipeline upstream of the infusion main pump from being vaporized, and the reflux valve can prevent the liquid ammonia in the cold-keeping reflux pipeline from being vaporized, thereby ensuring pipeline safety.

[0035] Optionally, in S1, the heating device is started to heat the liquid ammonia to the set temperature of the sequential delivery main pipeline, and the liquid ammonia is delivered to the sequential delivery main pipeline by the infusion main pump to prevent the large temperature difference between the liquid ammonia temperature and the delivery main pipeline from causing hot and cold alternating stress in the pipeline, and to prevent the soil around the buried pipeline from freezing and heaving and causing damage to the pipeline.

[0036] Optionally, in S2, the sealing valve is closed so that the liquid ammonia between the sealing valve and the infusion valve remains in liquid state. The liquid ammonia between the sealing valve and the heating device enters the cold-keeping reflux pipeline. This corresponds to the situation where the infusion main pump is far away from the injection point of the sequential transportation main pipeline. By maintaining the pressure between the sealing valve and the infusion valve, the pressure in this section of the pipeline is maintained above the saturated vapor pressure of ammonia at normal temperature. At this time, even if the pipeline is stopped and absorbs heat from the surrounding environment to raise the temperature of the liquid ammonia to normal temperature, the ammonia inside can still be kept in liquid state.

[0037] Example 1

[0038] When the main infusion pump is far away from the liquid ammonia injection point, a sealing valve is used. However, this distance is not enough for the liquid ammonia to absorb sufficient heat from the environment to heat up to the set temperature. A heating device is required. The device for sequentially injecting liquid ammonia and oil products into the delivery pipeline provided in this embodiment is as follows: Figure 1 As shown, it comprises: a liquid ammonia storage tank 1 and an oil storage tank 15, the liquid ammonia storage tank 1 is connected to a sequential delivery main pipeline 12 through a liquid ammonia delivery pipeline, and a liquid feed pump 4, a liquid infusion main pump 6 and a liquid infusion valve 10 are sequentially arranged on the liquid ammonia delivery pipeline; the liquid ammonia storage tank 1 is also connected to the liquid ammonia delivery pipeline between the liquid infusion main pump 6 and the liquid infusion valve 10 through a cold preservation return pipeline 3, and a return valve 2 is arranged on the cold preservation return pipeline 3;

[0039] The oil storage tank 15 is connected to the oil delivery main pipeline 12 through an oil delivery pipeline, and an oil delivery main pump 14 and an oil delivery valve 13 are sequentially arranged on the oil delivery pipeline.

[0040] Among them, the liquid ammonia storage tank 1 is a low-temperature and normal-pressure storage tank.

[0041] On the liquid ammonia delivery pipeline, a heating device 5 is provided between the liquid feed pump 4 and the main infusion pump 6; the function of the heating device 5 is to heat the liquid ammonia flowing out of the low-temperature atmospheric pressure storage tank to prevent the temperature of the liquid ammonia from being lower than 0°C when entering the downstream buried pipeline, thereby avoiding problems such as soil frost heave and thermal stress caused by alternating hot and cold transmission of the sequential delivery main pipeline.

[0042] The heating device 5 is close to the infusion main pump 6; the infusion main pump 6 is close to the cold-keeping reflux pipeline 3, and the reflux valve 2 on the reflux pipeline is close to the liquid ammonia storage tank 1.

[0043] A sealing valve 8 is provided between the infusion main pump 6 and the infusion valve 10 , and the cold-keeping return pipeline 3 is connected between the infusion main pump 6 and the sealing valve 8 .

[0044] The liquid feed pump 4 is located on the liquid ammonia delivery pipeline close to the liquid ammonia storage tank 1 .

[0045] The liquid ammonia transportation process provided by the device in this embodiment includes two processes including the main infusion process and the cold preservation circulation process; wherein, the starting point of the main infusion process is the low-temperature and normal-pressure liquid ammonia storage tank 1; the end point is the liquid ammonia injection point 11 that intersects with the sequential transportation main pipeline 12, and the injection point is located downstream of the oil delivery main pump 14 and the oil delivery valve 13 of the sequential transportation main pipeline 12; the main infusion process is connected in series with the main equipment such as the liquid feeding pump 4, the heating device 5, the liquid infusion main pump 6 and the liquid infusion valve 10 in sequence; the starting and ending points of the cold preservation circulation process are both the liquid ammonia storage tank 1 at low temperature and normal pressure, passing through the liquid feeding pump 4, the heating device 5, the liquid infusion main pump 6 in sequence, and connected to the cold preservation reflux pipeline 3 through the branch point 7 downstream of the liquid infusion main pump 6, and refluxed to the liquid ammonia storage tank 1 at low temperature and normal pressure; a reflux valve 2 is set at the end of the cold preservation reflux pipeline 3 near the liquid ammonia storage tank 1, and in the process of liquid ammonia being injected into the sequential transportation main pipeline 12, the valve adjusts the pressure in the cold preservation reflux pipeline 3 upstream thereof to be above the saturated vapor pressure of ammonia at the corresponding temperature.

[0046] The method for sequentially injecting liquid ammonia and oil products into a delivery pipeline based on the device of this embodiment includes the following process:

[0047] S1, the liquid ammonia delivered by the liquid ammonia storage tank 1 is pressurized to a saturated vapor pressure corresponding to the temperature of the liquid ammonia delivery pipeline by the liquid feed pump 4, the heating device 5 is started, the liquid ammonia is heated to the set temperature of the sequential delivery main pipeline 12, and the operating pressure of the sequential delivery main pipeline is provided by the liquid delivery main pump 6 to maintain the liquid delivery to the sequential delivery main pipeline 12, and at the same time, the reflux valve 2 is in a closed state, so that the liquid ammonia pressure in the cold preservation reflux pipeline 3 is above the saturated vapor pressure of ammonia corresponding to the temperature of the cold preservation reflux pipeline, and the oil delivery valve 13 is closed;

[0048] S2, the oil delivered by the oil storage tank 15 enters the sequential delivery main pipeline 12 through the oil delivery main pump 14 and the oil delivery valve 13; the reflux valve 2 is in the open state, the infusion valve 10 is in the closed state, and the sealing valve 8 is closed, so that the liquid ammonia inside the ammonia injection pipeline 9 between the sealing valve 8 and the infusion valve 10 remains in a high-pressure liquid state, and the heating device 5 is stopped. When the temperature of the liquid ammonia in the cold preservation circulation process downstream of the heating device 5 drops below the ammonia boiling point corresponding to the outlet pressure of the liquid feed pump 4, the liquid transport main pump 6 is stopped to provide power to the liquid feed pump 4, and a small amount of heated liquid ammonia between the sealing valve 8 and the heating device 5 enters the cold preservation reflux pipeline 3, and flows back to the liquid ammonia storage tank 1 through the cold preservation reflux pipeline 3, waiting for the next switching process.

[0049] Example 2

[0050] When the distance between the main infusion pump 6 and the liquid ammonia injection point 11 on the sequential delivery main pipeline 12 is relatively close, the technical solution without the sealing valve 8 is adopted. However, the main infusion pump 6 is relatively close to the liquid ammonia injection point 11, which also means that the main infusion process is relatively short, and the liquid ammonia therein cannot absorb enough heat to heat up to the set temperature. Therefore, it is necessary to set a heating device 5 so that the temperature of the liquid ammonia downstream of the main infusion pump 6 when entering the buried pipeline is not lower than 0°C. The difference between this embodiment and embodiment 1 is that the sealing valve 8 is not set.

[0051] Specific as Figure 2 As shown, the infusion valve 10 is close to the liquid ammonia injection point 11 which intersects with the sequential delivery main pipeline 12, and the branch point 7 of the cold preservation reflux pipeline 3 downstream of the infusion main pump 6 is set at a position close to the liquid ammonia injection point 11 and upstream of the infusion valve 10. Most of the liquid ammonia delivery pipeline is included in the cold preservation cycle process, and the medium in the pipe section between the infusion main pump 6 and the infusion valve 10 is maintained in liquid phase through the cold preservation cycle.

[0052] In other structures, the reflux valve 2 is as close to the liquid ammonia storage tank as possible. Then, in the process of sequentially injecting liquid ammonia and oil products into the delivery pipeline, the difference from embodiment 1 is:

[0053] In S1, after the liquid pump 4 pressurizes the liquid ammonia output from the liquid ammonia storage tank 1, the heating device 5 heats the liquid ammonia to a saturated vapor pressure above the saturated vapor pressure corresponding to the temperature of the liquid ammonia delivery pipeline, and the liquid infusion main pump 6 provides the operating pressure of the sequential delivery main pipeline when the liquid ammonia is injected into the sequential delivery main pipeline, maintaining the liquid delivery to the sequential delivery main pipeline 12.

[0054] In S2, the infusion valve 10 is closed, and the heating device 5 is turned off at the same time. At this time, the cold preservation reflux pipeline is opened, and the low-temperature liquid ammonia flows out from the liquid ammonia storage tank 1, gradually replacing the normal temperature medium in the original pipeline, and waiting for the liquid ammonia temperature to drop below the ammonia boiling point corresponding to the outlet pressure of the liquid feed pump 4, the transport liquid main pump 6 is stopped; since most of the liquid ammonia delivery pipeline is included in the cold preservation circulation process, the liquid ammonia in the liquid ammonia delivery pipeline can directly flow back into the liquid ammonia storage tank 1.

[0055] Example 3

[0056] When the main infusion pump is far away from the liquid ammonia injection point, a sealing valve is used, and the liquid ammonia transportation distance is sufficient for the liquid ammonia to absorb sufficient heat from the environment to heat up to the set temperature. Therefore, there is no need to set the heating device 5. The difference between the device of this embodiment and embodiment 1 is that the heating device 5 is not set.

[0057] Correspondingly, in the S1 process, the liquid feed pump 4 pressurizes the liquid ammonia to a saturated vapor pressure corresponding to the temperature of the liquid ammonia delivery pipeline, and provides the operating pressure of the sequential delivery main pipeline through the infusion main pump 6. The liquid ammonia absorbs heat from the environment during the delivery process to reach the set temperature. The above is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A device for sequentially injecting liquid ammonia and oil products into a delivery pipeline, characterized in that: include: The liquid ammonia storage tank and the oil storage tank, the liquid ammonia storage tank is connected to the sequential delivery main pipeline through a liquid ammonia delivery pipeline, and the liquid ammonia delivery pipeline is sequentially provided with a liquid feed pump, a liquid infusion main pump and a liquid infusion valve; the liquid ammonia storage tank is also connected to the liquid ammonia delivery pipeline between the liquid infusion main pump and the liquid infusion valve through a cold-keeping return pipeline, and the cold-keeping return pipeline is provided with a return valve; The oil storage tank is connected to the main oil delivery pipeline in sequence through the oil delivery pipeline, and the oil delivery main pump and oil delivery valve are arranged in sequence on the oil delivery pipeline.

2. The device for sequentially injecting liquid ammonia and oil products into a delivery pipeline according to claim 1, characterized in that: A heating device is provided on the liquid ammonia delivery pipeline between the liquid feeding pump and the liquid infusion main pump.

3. The device for sequentially injecting liquid ammonia and oil products into a delivery pipeline according to claim 2, characterized in that: The heating device is close to the main infusion pump.

4. The device for sequentially injecting liquid ammonia and oil products into a delivery pipeline according to claim 1, characterized in that: The main infusion pump is close to the cold return line.

5. The device for sequentially injecting liquid ammonia and oil products into a delivery pipeline according to claim 1, characterized in that: A sealing valve is arranged between the infusion main pump and the infusion valve, and the cold-keeping return pipeline is connected between the infusion main pump and the sealing valve.

6. The device for sequentially injecting liquid ammonia and oil products into a delivery pipeline according to claim 1, characterized in that: The liquid feed pump is close to the liquid ammonia storage tank, or installed inside the liquid ammonia storage tank.

7. The device for sequentially injecting liquid ammonia and oil products into a delivery pipeline according to claim 1, characterized in that: The reflux valve is close to the liquid ammonia storage tank, or is installed inside the liquid ammonia storage tank.

8. A method for sequentially injecting liquid ammonia and oil products into a delivery pipeline based on the device for sequentially injecting liquid ammonia and oil products into a delivery pipeline as claimed in any one of claims 1 to 7, characterized in that: The process includes: S1. The liquid ammonia transported by the liquid ammonia storage tank is pressurized by the liquid pump to a level above the saturated vapor pressure of ammonia corresponding to the highest temperature of the liquid ammonia transport pipeline upstream of the infusion main pump. The infusion main pump provides the operating pressure of the sequential transport main pipeline to maintain liquid transport to the sequential transport main pipeline. At the same time, the reflux valve is in a closed state, so that the liquid ammonia pressure in the cold-keeping reflux pipeline is above the saturated vapor pressure of the cold-keeping reflux pipeline temperature, and the oil delivery valve is closed; S2. The oil products transported from the oil storage tank enter the sequential transportation main pipeline through the oil delivery main pump and the oil delivery valve; the reflux valve is in the open state, the infusion valve is in the closed state, the infusion main pump is stopped, and the liquid feed pump is running to make the liquid ammonia in the liquid ammonia delivery pipeline flow back to the liquid ammonia storage tank through the cold-insulated reflux pipeline.

9. The method for sequentially injecting liquid ammonia and oil products into a delivery pipeline according to claim 8, characterized in that: In S1, the heating device is started to heat the liquid ammonia to the set temperature of the sequential delivery main pipeline, and the liquid ammonia is delivered to the sequential delivery main pipeline by the infusion main pump.

10. The method for sequentially injecting liquid ammonia and oil products into a delivery pipeline according to claim 8, characterized in that: In S2, the sealing valve is closed, so that the liquid ammonia between the sealing valve and the infusion valve remains in liquid state.

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