A methanol unloading system

Abstract

The application discloses a methanol unloading system, which comprises a liquid inlet pipeline, a liquid outlet pipeline, an unloading pump, a gas-liquid separation tank and a backflow pipeline; the liquid outlet end of the unloading pump is communicated with the gas-liquid separation tank through an exhaust pipeline; the gas-liquid separation tank is communicated with the liquid inlet end of the unloading pump through the backflow pipeline; a backflow valve is arranged at the connection position of the backflow pipeline and the gas-liquid separation tank; the system further comprises a liquid pumping pump, a liquid pumping inlet pipe and a liquid pumping outlet pipe; the liquid pumping inlet pipe is communicated between the backflow pipeline and the liquid inlet end of the liquid pumping pump; the liquid pumping outlet pipe is communicated between the liquid outlet end of the liquid pumping pump and the liquid outlet pipeline; a liquid pumping inlet valve is arranged on the liquid pumping inlet pipe; the system further comprises a backflow bypass pipeline, one end of the backflow bypass pipeline is communicated with the backflow pipeline and is provided with a bypass valve, and the end is located between the liquid pumping inlet valve and the backflow valve; the other end of the backflow bypass pipeline is communicated with the end of the backflow pipeline close to the unloading pump. By adding the additional liquid pumping pipeline and the liquid pumping pump, the dynamic change of the unloading working condition and the safety requirement can be adapted.

Description

Technical Field

[0001] This utility model relates to the technical field of unloading systems, specifically to a methanol unloading system. Background Technology

[0002] Methanol, as a basic chemical raw material, is widely used in chemical, energy, and pharmaceutical fields. Many companies need to purchase large quantities of methanol via tank trucks to meet their production needs. In the methanol unloading process, the unloading system is a key piece of equipment connecting the tank truck and the storage tank. Its core function is to safely and efficiently transport the methanol from the tank truck to the storage tank.

[0003] The existing methanol unloading system mainly consists of an inlet pipeline, an unloading pump, a gas-liquid separator, a return pipeline, and an outlet pipeline. An exhaust pipeline connected to the gas-liquid separator is installed at the unloading pump outlet. According to operating procedures, the outlet pipeline of the unloading pump must be vented before each start-up; otherwise, residual gas will cause cavitation. The methanol discharged with the gas enters the gas-liquid separator and then flows back to the unloading pump inlet via the return pipeline. The returned methanol replenishes the medium at the inlet, fills the air gaps, and ensures that the unloading pump is always filled with methanol, thus preventing cavitation at its source.

[0004] However, in practical industrial applications, it has been found that relying solely on the reflux pipeline and a fixed-opening reflux valve for methanol reflux fails to consider the dynamic changes in unloading conditions. When the daily unloading volume is large, frequent venting operations are required. At this time, the methanol level in the gas-liquid separator rises rapidly, and the fixed-opening reflux valve can only provide a constant reflux flow, which cannot discharge the methanol in the tank in time, easily leading to overflow and posing a risk of methanol leakage. On the other hand, if accidents such as jamming of the reflux valve in the reflux pipeline or failure of the unloading pump occur, the lack of a backup flow path will prevent the methanol in the gas-liquid separator from being discharged or interrupt the unloading process. This can cause production delays or, in severe cases, lead to combustion and explosion accidents due to methanol overflow. Utility Model Content

[0005] The present invention aims to provide a methanol unloading system that adapts to dynamic changes in unloading conditions and safety requirements by adding additional liquid extraction pipelines and pumps.

[0006] To address the above problems, this application provides the following technical solution: A methanol unloading system includes an inlet pipeline, an outlet pipeline, an unloading pump, a gas-liquid separator, and a return pipeline. The outlet of the unloading pump is connected to the gas-liquid separator via an exhaust pipeline, and the gas-liquid separator is connected to the inlet of the unloading pump via the return pipeline. A return valve is provided at the connection between the return pipeline and the gas-liquid separator. The system further includes a pump, a pump inlet pipe, and a pump outlet pipe. The pump inlet pipe is connected between the return pipeline and the pump inlet, and the pump outlet pipe is connected between the pump outlet and the outlet pipeline. A pump inlet valve is provided on the pump inlet pipe. The system also includes a return bypass, one end of which is connected to the return pipeline and has a bypass valve, and this end is located between the pump inlet valve and the return valve. The other end of the return bypass is connected to the end of the return pipeline closest to the unloading pump.

[0007] The working principle and beneficial effects of this utility model: When the system is in normal unloading condition, the liquid level in the gas-liquid separator rises slowly. By closing the bypass valve and the liquid inlet valve, the methanol in the gas-liquid separator flows back to the liquid inlet of the unloading pump through the return pipeline, and then is pumped into the liquid storage tank through the liquid outlet pipeline. The returned methanol can replenish the medium at the liquid inlet, fill the air gap, and ensure that the unloading pump is always full of methanol, thus avoiding cavitation at the source.

[0008] When the system is operating at high frequency during unloading, the liquid level in the gas-liquid separator rises rapidly. Relying solely on the return pipeline cannot promptly drain the methanol from the separator, potentially leading to overflow and methanol leakage. In this situation, the inlet valve and bypass valve are opened, and the pump is started. Methanol from the return pipeline is introduced into the pump through the inlet pipe, pressurized, and then pumped directly to the outlet pipeline through the outlet pipe, merging with the mainstream methanol discharged from the unloading pump. Furthermore, the bypass valve is located between the inlet valve and the return valve. This design ensures that after the pump starts (its high power can easily create a strong negative pressure in the return pipeline), the opening of the bypass valve is adjusted to allow some methanol to bypass the pump and flow directly back to the unloading pump inlet via the return bypass. This diversion maintains the medium supply at the unloading pump inlet, preventing insufficient supply due to excessive pumping, while ensuring continuous filling of air gaps with returning methanol to prevent cavitation risks from recurring.

[0009] In addition, when the unloading pump malfunctions (under maintenance), the bypass valve is closed, the liquid extraction inlet valve and the liquid extraction pump are opened, and the reflux methanol is directly drawn into the liquid outlet pipeline; when the liquid extraction pump malfunctions (under maintenance), the liquid extraction inlet valve is closed, and the methanol flows back to the unloading pump through the reflux pipeline. There is an alternative solution for any single-path failure, the system has no risk of single-point failure, ensures the continuity of operation, and provides sufficient time for maintenance.

[0010] As a preferred embodiment, the top of the gas-liquid separator is connected to the atmosphere via a high-point venting pipe, and the high-point venting pipe is equipped with an activated carbon adsorption layer.

[0011] As a preferred embodiment, the liquid inlet pipeline is connected to multiple branch pipes.

[0012] As a preferred embodiment, the liquid extraction outlet pipe is equipped with a check valve.

[0013] As a preferred embodiment, the exhaust pipe is equipped with an exhaust valve. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of an existing methanol unloading system; Figure 2 This is a schematic diagram of the structure of a methanol unloading system according to this application.

[0015] The reference numerals in the accompanying drawings include: 1. Reflux valve; 2. Gas-liquid separator; 3. High-point venting line; 4. Liquid outlet line; 5. Exhaust valve; 6. Exhaust line; 7. Unloading pump; 8. Liquid inlet line; 9. Reflux line; 10. Reflux bypass; 11. Bypass valve; 12. Liquid extraction outlet pipe; 13. Liquid extraction pump; 14. Liquid extraction inlet valve; 15. Shut-off valve; 16. Liquid extraction inlet pipe. Detailed Implementation

[0016] The following detailed description illustrates the specific implementation method: Example: Refer to Figure 2 A methanol unloading system includes an inlet pipe 8, an outlet pipe 4, an unloading pump 7, a gas-liquid separator 2, and a return pipe 9. The outlet end of the inlet pipe 8 is connected to the inlet end of the unloading pump 7, and the outlet end of the unloading pump 7 is connected to the inlet end of the outlet pipe 4. An inlet valve is provided on the inlet pipe 8. The outlet end of the unloading pump 7 is also connected to the inlet of the gas-liquid separator 2 through an exhaust pipe 6. An exhaust valve 5 is provided on the exhaust pipe 6. A return valve 1 and a shut-off valve 15 are provided on the return pipe 9. A high-point vent pipe 3 is connected to the top of the gas-liquid separator 2.

[0017] It also includes a liquid pump 13, a liquid inlet pipe 16, and a liquid outlet pipe 12. The liquid inlet pipe 16 is connected between the return pipe 9 and the liquid inlet end of the liquid pump 13, and the liquid outlet pipe 12 is connected between the liquid outlet end of the liquid pump 13 and the liquid outlet pipe 4. The liquid inlet pipe 16 is equipped with a liquid inlet valve 14. It also includes a return bypass 10. The two ends of the return bypass 10 are respectively connected to the return pipe 9, and both are equipped with bypass valves 11.

[0018] When the system is in normal unloading condition, the liquid level in the gas-liquid separator 2 rises slowly. The bypass valve 11 and the liquid extraction inlet valve 14 are closed, and the shut-off valve 15 and the return valve 1 are opened. The methanol in the gas-liquid separator 2 flows back to the liquid inlet of the unloading pump 7 through the return pipeline 9, and then is pumped into the liquid outlet pipeline 4 to the storage tank through the unloading pump 7. The returned methanol can replenish the medium at the liquid inlet, fill the air gap, and ensure that the unloading pump 7 is always full of methanol, thus avoiding cavitation at the source.

[0019] When the system is in high-frequency unloading mode, the liquid level in the gas-liquid separator 2 rises rapidly. The reflux line 9 alone cannot discharge the methanol from the gas-liquid separator 2 in time, easily leading to overflow and a risk of methanol leakage. At this time, the pump inlet valve 14, bypass valve 11, shut-off valve 15, and reflux valve 1 are opened, and the pump 13 is started. Methanol from the reflux line 9 is introduced into the pump 13 through the pump inlet pipe 16, pressurized, and then directly pumped to the outlet pipe 4 through the pump outlet pipe 12, merging with the mainstream methanol discharged from the unloading pump 7. Furthermore, the pump 13 has a high power output after startup, easily creating a strong negative pressure in the reflux line 9. By adjusting the opening of the bypass valve 11, some methanol is ensured to bypass the pump 13 and flow directly back to the inlet of the unloading pump 7 through the reflux bypass 10. This diversion method can maintain the medium replenishment at the inlet of the unloading pump 7, avoid insufficient liquid supply at the inlet of the unloading pump 7 due to excessive extraction by the pump 13, and at the same time ensure that the refluxed methanol continuously fills the air gap to prevent the risk of cavitation from recurring.

[0020] In addition, when the unloading pump 7 malfunctions (requires maintenance), the bypass valve 11 and the shut-off valve 15 are closed, and the liquid extraction inlet valve 14, the liquid extraction pump 13, and the return valve 1 are opened, allowing the methanol to be directly drawn into the liquid outlet line 4. When the liquid extraction pump 13 malfunctions (requires maintenance), the liquid extraction inlet valve 14 and the bypass valve 11 are closed, and the methanol is returned to the unloading pump 7 through the return line 9. There is an alternative solution for any single-path failure, the system has no risk of single-point failure, ensures the continuity of operation, and provides sufficient time for maintenance.

[0021] It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solution of this utility model. These modifications and improvements should also be considered within the scope of protection of this utility model, and will not affect the effectiveness of the implementation of this utility model or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A methanol unloading system, comprising an inlet pipeline, an outlet pipeline, an unloading pump, a gas-liquid separator, and a return pipeline; the outlet of the unloading pump is connected to the gas-liquid separator via an exhaust pipeline, and the gas-liquid separator is connected to the inlet of the unloading pump via a return pipeline; a return valve is provided at the connection between the return pipeline and the gas-liquid separator, characterized in that: It also includes a liquid pump, a liquid inlet pipe, and a liquid outlet pipe. The liquid inlet pipe is connected between the return pipeline and the liquid inlet end of the liquid pump, and the liquid outlet pipe is connected between the liquid outlet end of the liquid pump and the liquid outlet pipeline. The liquid inlet pipe is equipped with a liquid inlet valve. It also includes a return bypass. One end of the return bypass is connected to the return pipeline and is equipped with a bypass valve. This end is located between the liquid inlet valve and the return valve. The other end of the return bypass is connected to the end of the return pipeline near the unloading pump.

2. The methanol unloading system according to claim 1, characterized in that: The top of the gas-liquid separator is connected to the atmosphere through a high-point venting pipe, which is equipped with an activated carbon adsorption layer.

3. The methanol unloading system according to claim 2, characterized in that: The incoming liquid pipeline is connected to multiple branch pipes.

4. The methanol unloading system according to claim 3, characterized in that: The liquid extraction outlet pipe is equipped with a check valve.

5. The methanol unloading system according to claim 4, characterized in that: The exhaust pipe is equipped with an exhaust valve.

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