A pressure control system and method for methanol day tanks on a dual-fuel ship

Abstract

This invention relates to the field of ship design technology and discloses a pressure control system and method for a methanol day tank of a dual-fuel ship. The pressure control system includes: a methanol storage tank, a first transfer pump, a methanol day tank, a variable frequency transfer pump, a main engine and a generator, a first flow meter and a second flow meter. One end of the first transfer pump is connected to the methanol storage tank, and the other end of the first transfer pump is simultaneously connected to two flow adjustment pipelines. The two flow adjustment pipelines are simultaneously connected to the methanol day tank. The methanol day tank simultaneously delivers methanol fuel to the main engine and the generator through the two variable frequency transfer pumps. The system also includes a remote control box, which is used to control the flow regulating valve and the remote control three-way valve, and to interact with the first and second flow meters. The system has advantages such as more precise flow control at the inlet and outlet of the day tank, and a simple and reliable overall system.

Description

Technical Field

[0001] This invention relates to the field of ship design technology, and in particular to a pressure control system and control method for the methanol day tank of a dual-fuel ship. Background Technology

[0002] As global climate change governance deepens, the shipping industry is facing unprecedented challenges in carbon reduction. To accelerate the low-carbon transition, methanol fuel, with its significant advantage of low carbon emission intensity and relatively complete technological system, is gradually becoming a key technology option for the shipping industry. It has already been commercially applied in projects such as 24,000 TEU methanol-powered container ships.

[0003] In the design of ships using methanol as fuel, the methanol fuel transportation and supply system is typically a closed system due to the toxicity of methanol fuel. During operation, the methanol storage tank transfers methanol to the methanol day tank via a transfer pump, from where it is then supplied to the main engine and generator.

[0004] However, the methanol transfer process in the existing technology still faces some technical challenges. First, due to the high volatility of methanol, nitrogen is usually used to pressurize the methanol day tank. When methanol fuel is transferred from the methanol storage tank to the day tank, the pressure inside the methanol day tank increases significantly and needs to be released. When methanol is transferred from the day tank to the main engine and generator, the pressure inside the methanol day tank decreases significantly, and gas needs to be added to achieve pressure balance.

[0005] Currently, there are two ways to maintain pressure balance in the methanol day tank. One is to use a PV (pressure / vacuum) valve for pressure balance. This method pollutes the atmosphere, increases nitrogen consumption, and frequent use makes the PV valve more prone to damage. The other method is to use a pressure balance pipeline to connect the methanol fuel day tank and the methanol storage tank. This method may pass through a safety zone when the ship is large, requiring the use of double-walled pipes. The use of double-walled pipes requires consideration of ventilation and is expensive, increasing construction costs.

[0006] Therefore, in view of the above problems, in order to effectively regulate and control the pressure of the methanol day tank during methanol fuel transshipment, this application provides a pressure control system and method for the methanol day tank of a dual-fuel ship. Summary of the Invention

[0007] The main objective of this invention is to address some technical challenges that still exist in the methanol transfer process in the prior art. For example, due to the high volatility of methanol, nitrogen is usually used to seal the methanol day tank. When methanol fuel is transferred from the methanol storage tank to the day tank, the pressure inside the methanol day tank increases significantly and needs to be released. When methanol is transferred from the day tank to the main engine and generator, the pressure inside the methanol day tank decreases significantly, and gas needs to be added to achieve pressure balance.

[0008] In a first aspect, the present invention provides a pressure control system for the methanol day tank of a dual-fuel ship, the pressure control system comprising:

[0009] The system includes a methanol storage tank, a first transfer pump, a methanol day-use tank, a variable frequency transfer pump, a main engine, and a generator. One end of the first transfer pump is connected to the methanol storage tank, and the other end of the first transfer pump is simultaneously connected to two flow adjustment pipelines. The two flow adjustment pipelines are simultaneously connected to the methanol day-use tank. The methanol day-use tank simultaneously delivers methanol fuel to the main engine and the generator via the two variable frequency transfer pumps. The system also includes a remote control box, which is used to control the flow regulating valve and the remote control three-way valve, and to exchange signals with the first flow meter and the second flow meter.

[0010] Optionally, it also includes a T-type three-way valve, the main line of which is connected to the methanol storage chamber, and the two branches of which are respectively connected to a flow adjustment pipeline.

[0011] Optionally, the flow adjustment pipeline includes a flow regulating valve, a first flow meter, a remote-controlled three-way valve, a second check valve, and a return pipe. The flow regulating valve, the first flow meter, the remote-controlled three-way valve, and the second check valve are connected in sequence. One end of the return pipe is connected to the remote-controlled three-way valve, and the other end of the return pipe is connected to the inlet of the flow regulating valve. A first check valve is provided on the return pipe, and the inlet of the first flow valve is also connected to the T-type three-way valve.

[0012] Optionally, it also includes a methanol day tank inlet transport pipeline, one end of which is connected to a second check valve, and the other end of which is connected to the methanol day tank.

[0013] Optionally, it also includes a methanol day-use tank outlet transshipment pipeline, one end of which is connected to the methanol day-use tank, and the other end of which is connected to two variable frequency transshipment pumps.

[0014] Optionally, one of the variable frequency transport pumps is connected to the main unit via a second flow meter, and the other variable frequency transport pump is connected to the generator via another second flow meter.

[0015] Optionally, the remote control box is used to control the flow regulating valve, the first flow meter, the remote-controlled three-way valve, and the second flow meter.

[0016] Secondly, this application also provides a method for controlling the pressure of the methanol day tank on a dual-fuel ship, the method comprising:

[0017] Step S1: Real-time monitoring of host / generator load;

[0018] Step S2: Adjust the flow rate of the variable frequency transport pump to meet the demand;

[0019] Step S3: Calculate the required adjustment degree based on the flow meter readings on the inlet and outlet sides of the methanol daily use tank;

[0020] Step S4: Adjust the opening of the flow regulating valve;

[0021] Step S5: If the flow meter readings on the inlet and outlet sides of the methanol daily use compartment are inconsistent, repeat steps S3 and S4;

[0022] Step S6: When the flow meter readings on the inlet and outlet sides of the methanol daily use compartment are consistent, the adjustment is complete.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] Compared to existing technologies, this invention primarily addresses the pressure fluctuation problem in methanol daily use tanks caused by the transshipment of methanol fuel at the inlet and outlet. By controlling the consistent flow rates at the inlet and outlet of the methanol daily use tank, the stability of the liquid level within the tank is ensured. Combined with nitrogen sealing for pressure control, this avoids contact between methanol fuel and nitrogen and the atmospheric environment, reducing methanol vapor pollution and nitrogen consumption. Furthermore, the rational use of parallel branches for independent flow control, combined with logic control methods, results in more precise flow control at the inlet and outlet of the daily use tank. The entire system is simple and reliable; these are all technical effects directly resulting from these technological features. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the methanol fuel day tank pressure control system according to an embodiment of the present invention;

[0026] Figure 2 This is a flowchart of the logical method of the present invention.

[0027] In the diagram: 1-First transfer pump; 2-T-type three-way valve; 3-Flow regulating valve; 4-First flow meter; 5-Remote control three-way valve; 6-Return pipe; 7-First check valve; 8-Second check valve; 9-Methanol daily use tank inlet transfer pipeline; 10-Methanol daily use tank; 11-Methanol daily use tank outlet transfer pipeline; 12-Variable frequency transfer pump; 13-Second flow meter; 14-Remote control box. Detailed Implementation

[0028] This invention provides a pressure control system and method for the methanol day tank of a dual-fuel ship. The pressure control system includes: a methanol storage tank, a first transfer pump, a methanol day tank, a variable frequency transfer pump, a main engine, and a generator. One end of the first transfer pump is connected to the methanol storage tank, and the other end of the first transfer pump is simultaneously connected to two flow adjustment pipelines. The two flow adjustment pipelines are simultaneously connected to the methanol day tank, and the methanol day tank is simultaneously connected to the main engine and the generator. The invention also includes a remote control box for controlling the flow adjustment pipelines. The main objective of this invention is to address some technical challenges still existing in the methanol transfer process in the prior art. For example, due to the high volatility of methanol, nitrogen is usually used for pressure sealing in the methanol day tank. When methanol fuel is transferred from the methanol storage tank to the day tank, the pressure inside the methanol day tank increases significantly and needs to be released; when methanol is transferred from the day tank to the main engine and generator, the pressure inside the methanol day tank decreases significantly, requiring the addition of gas to achieve pressure balance.

[0029] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" or "having" and any variations thereof are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0030] For ease of understanding, the specific process of the embodiments of the present invention is described below. An embodiment of the pressure control system and control method for methanol day tanks of a dual-fuel ship provided by the present invention includes:

[0031] 1. First transport pump; 2. T-type three-way valve; 3. Flow regulating valve; 4. First flow meter; 5. Remote control three-way valve; 6. Return pipe; 7. First check valve; 8. Second check valve; 9. Methanol daily use tank inlet transport pipeline; 10. Methanol daily use tank; 11. Methanol daily use tank outlet transport pipeline; 12. Variable frequency transport pump; 13. Second flow meter; 14. Remote control box. The following is a detailed description through an embodiment.

[0032] The methanol storage tank sends methanol fuel to the methanol daily use tank 10 via the first transfer pump 1, and then sends the methanol fuel to the main engine and generator respectively via two variable frequency transfer pumps 12. The two variable frequency transfer pumps 12 operate independently and adjust the flow rate according to the working load of the main engine and generator respectively, which not only ensures the fuel demand of the machine, but also reduces fuel waste.

[0033] In an optional embodiment, a T-type three-way valve 2 and two flow regulation pipelines are provided between the first transport pump 1 and the methanol daily use tank 10. After the methanol fuel is diverted by the T-type three-way valve 2, it enters the two flow regulation pipelines. The two flow regulation pipelines operate independently and correspond to the main unit and generator respectively to ensure the accuracy of flow regulation.

[0034] In an optional embodiment, the flow adjustment pipeline is equipped with a flow regulating valve 3, a first flow meter 4, a remote-controlled three-way valve 5, a return pipe 6, and a second check valve 8, with a first check valve 7 installed on the return pipe. The first check valve 7 and the second check valve 8 are used to prevent methanol fuel backflow at the branch pipe.

[0035] In an optional embodiment, a second flow meter 13 is provided between the variable frequency transport pump 12 and the main unit and the generator, respectively.

[0036] In an optional embodiment, a remote control box 14 is provided and connected to the flow regulating valve 3, the remote control three-way valve 5, the first flow meter 4, and the second flow meter 13, and remotely controls them through signal transmission.

[0037] The operating principle of the methanol day tank pressure control system for the dual-fuel ship in this embodiment is as follows:

[0038] After the operating load of the main unit or generator changes, the corresponding variable frequency transfer pump 12 changes its frequency in real time to adjust the flow rate. The first flow meter 4 and the second flow meter 13 transmit the flow rate reading to the remote control box 14 in real time. The remote control box 14 compares the two readings. If the flow rates are consistent, the methanol fuel is sent to the methanol daily use compartment 10. If the flow rates are inconsistent, the required opening degree is calculated and transmitted to the flow regulating valve 3 via a signal. The flow regulating valve 3 adjusts the opening degree according to the received signal. The first flow meter 4 transmits the adjusted flow rate reading back to the remote control box 14 and makes another judgment. If the flow rates are consistent, the methanol fuel is sent to the methanol daily use compartment 10. If the flow rates are inconsistent, the signal is transmitted to the flow regulating valve 3 and the remote control three-way valve 5. The remote control three-way valve 5 adjusts the flow direction according to the received signal. The methanol fuel returns to the flow regulating valve 3 through the return pipe 6 and the flow rate is readjusted. The above operation is repeated until the flow rates are consistent. After the flow rate adjustment is completed, the remote control three-way valve 5 readjusts the flow direction, and the methanol fuel is sent to the methanol daily use compartment 10.

[0039] like Figure 2 As shown, the control flow of the methanol day tank pressure control method for dual-fuel ships in this embodiment is as follows:

[0040] 1. Real-time monitoring of host / generator load.

[0041] 2. Determine if the load on the main unit / generator has changed;

[0042] 3. If there is no change, return to step 1.

[0043] 4. If there are changes, proceed to the next step.

[0044] 5. Adjust the flow rate of the variable frequency transport pump.

[0045] 6. Determine whether the readings of the first flow meter 4 and the second flow meter 13 are consistent;

[0046] 7. If they match, return to step 1.

[0047] 8. If there is no agreement, proceed to the next step.

[0048] 9. Calculate the required adjustment opening.

[0049] 10. Adjust the opening degree of the flow regulating valve.

[0050] 11. Determine whether the readings of the first flow meter 4 and the second flow meter 13 are consistent;

[0051] 12. If there is a discrepancy, return to step 9.

[0052] 13. If they are consistent, it means that the inlet and outlet flow rates of the methanol daily use tank are consistent, and the adjustment is complete.

[0053] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling the pressure of the methanol day tank on a dual-fuel ship, implemented based on a pressure control system for the methanol day tank on a dual-fuel ship, characterized in that... The pressure control system for the methanol day tank of a dual-fuel ship includes a methanol storage tank, a first transfer pump, a methanol day tank, a variable frequency transfer pump, a main engine, a generator, a first flow meter, and a second flow meter. One end of the first transfer pump is connected to the methanol storage tank, and the other end of the first transfer pump is simultaneously connected to two flow adjustment pipelines. The two flow adjustment pipelines are simultaneously connected to the methanol day tank. The methanol day tank simultaneously delivers methanol fuel to the main engine and the generator through the two variable frequency transfer pumps. The system also includes a remote control box, which is used to control the flow regulating valve and the remote control three-way valve, and to interact with the first and second flow meters. The flow adjustment pipeline includes a flow regulating valve, a first flow meter, a remote-controlled three-way valve, a second check valve, and a return pipe. The flow regulating valve, the first flow meter, the remote-controlled three-way valve, and the second check valve are connected in sequence. One end of the return pipe is connected to the remote-controlled three-way valve, and the other end of the return pipe is connected to the inlet of the flow regulating valve. The return pipe is equipped with a first check valve. The method for controlling the pressure in the methanol day tank of a dual-fuel ship includes: S1. Real-time monitoring of host / generator load; S2. Determine if the load on the main unit / generator has changed; S3. If there is no change, return to step S1; S4. If there are changes, proceed to the next step; S5. Variable frequency transport pump adjusts flow rate; S6. Determine whether the readings of the first flow meter and the second flow meter are consistent; S7. If they match, return to step S1; S8. If there is no agreement, proceed to the next step; S9. Calculate the required adjustment angle; S10. Flow control valve adjusts the opening degree; S11. Determine whether the readings of the first flow meter and the second flow meter are consistent; S12. If there is a discrepancy, return to step S9; S13. If they are consistent, it means that the inlet and outlet flow rates of the methanol daily use tank are consistent, and the adjustment is over.

2. The method for controlling the pressure of the methanol day tank on a dual-fuel ship according to claim 1, characterized in that, It also includes a T-type three-way valve, the main pipe of which is connected to the methanol storage chamber, and the two branches of which are respectively connected to a flow adjustment pipeline.

3. The method for controlling the pressure of the methanol day tank on a dual-fuel ship according to claim 2, characterized in that, It also includes a methanol day tank inlet transport pipeline, one end of which is connected to a second check valve, and the other end of which is connected to the methanol day tank.

4. The method for controlling the pressure of the methanol day tank on a dual-fuel ship according to claim 3, characterized in that, It also includes a methanol day-use tank outlet transport pipeline, one end of which is connected to the methanol day-use tank, and the other end of which is connected to two variable frequency transport pumps.

5. The method for controlling the pressure of the methanol day tank on a dual-fuel ship according to claim 4, characterized in that, One of the variable frequency transport pumps is connected to the main unit via a second flow meter, and the other variable frequency transport pump is connected to the generator via another second flow meter.

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