Liquefied gas cargo carrier emergency valve drive system

Abstract

There is disclosed a liquefied gas cargo carrier emergency valve drive system, comprising one or more hydraulic accumulators configured to provide hydraulic fluid to emergency valves controlling the handling of a liquefied gas cargo on the carrier, and a hydraulic pressure intensifier configured for storing the hydraulic fluid in the one or more hydraulic accumulators at a pressure above 150 barg.

Description

[0001] LIQUEFIED GAS CARGO CARRIER EMERGENCY VALVE DRIVE SYSTEM

[0002] The present application generally relates to hydraulic accumulators for emergency valves on liquefied gas cargo carriers, and more particularly to the design and functionality of such accumulators, and a liquefied gas cargo carrier having such a drive system.

[0003] Liquefied gas cargo carriers are used all over the world, for cargo carrying liquefied gases such as hydrocarbons like LPG, ammonia, and now carbon dioxide. Such liquefied gas cargo carriers use a range of valves to control the flow and distribution of the cargo and boil off gases in a manner known in the art. Such valves are controlled by a hydraulic system relying on one or more electric pumps to operate.

[0004] Where a power failure occurs, every liquefied gas cargo carrier must have a back-up system. Such backup systems are typically one or more hydraulic fluid accumulators, ready to provide a supply of hydraulic fluid to operate emergency valves at their standard delivery pressure. The standard delivery pressure is commonly 135 barg on liquefied gas cargo carriers.

[0005] This application addresses the problem of improving the emergency valve drive system for liquefied gas cargo carriers.

[0006] The application provides solutions for enhancing the efficiency and effectiveness of emergency valves controlling the handling of liquefied gas cargo, by utilizing hydraulic accumulators and a hydraulic pressure intensifier to store hydraulic fluid at a pressure above the conventional pressure. Additionally, the application introduces a pressure reducer to reduce the pressure in the accumulators when necessary.

[0007] According to a first aspect of the present invention, there is provided a liquefied gas cargo carrier emergency valve drive system, comprising one or more hydraulic accumulators configured to provide hydraulic fluid to emergency valves controlling the handling of a liquefied gas cargo on the carrier, and a hydraulic pressure intensifier configured for storing the hydraulic fluid in the one or more hydraulic accumulators at a pressure above 150 barg. Optionally, the hydraulic fluid from the one or more accumulators is provided directly to operate the emergency valves, or is provided to one or more intermediate reservoirs or units, such as a hydraulic power pack, able to hence operate the emergency valves.

[0008] The incorporation of one or more hydraulic accumulators able to supply hydraulic fluid in an emergency at above conventional pressure increases the useable volume of hydraulic fluid in the accumulators, and therefore increases the assurity of a reliable supply of hydraulic fluid (which is also subject to physical property changes associated with temperature changes) to the emergency valves, which is critical for maintaining control over the handling of liquefied gas cargo in emergency situations. It also makes the present invention more robust to changing properties of the fluid associated with temperature changes.

[0009] Thus, the system of the present invention provides enhanced safety for the liquefied gas cargo carrier by ensuring that the emergency valves can be operated promptly and effectively when needed, thereby minimizing the risk of accidents or cargo loss.

[0010] Furthermore, liquefied gas cargo carriers are using an increasing number of hydraulicly operated system and valves, but the size of the vessel or the space in the vessel cannot be increased. The present invention allows an emergency valve drive system to use hydraulic accumulators able to store a greater volume of hydraulic fluid for the same space, offering a compact and efficient solution for energy storage, which can be crucial in the space-constrained environment of a liquefied gas cargo carrier.

[0011] The system's hydraulic pressure intensifier stores hydraulic fluid in the accumulators at a pressure above 150 barg, resulting in enhanced performance and reliability of the emergency valves.

[0012] Optionally, the system's hydraulic pressure intensifier stores hydraulic fluid in the accumulators at a pressure above 200 barg. The skilled person can see that the system's hydraulic pressure intensifier can store hydraulic fluid in the accumulators up to the maximum pressure possible win the accumulators. This can be higher than 200 barg. The inclusion of a pressure reducer in the system allows for the reduction of higher than operational pressure in the hydraulic accumulators to a conventional or normal operational pressure. This could be below 150 barg, such as in the range 130 barg to 140 barg, providing the advantage of increased clarity and control over the handling of the liquefied gas cargo valves in an emergency.

[0013] The system's ability to reduce the pressure in the hydraulic accumulators to a range between 130 barg and 140 barg, such as but not limited to 135 barg, offers the advantage of improved extensibility, allowing for flexibility in adjusting the pressure levels based on specific operational requirements.

[0014] The disclosed system's use of hydraulic pressure intensifiers creates greater useable hydraulic volume in the accumulators, leading to a simpler and more efficient design of the emergency valve drive system. Such efficiency may include a reduction in the number of accumulators required to still operate the emergency valve drive system, creating a potential space saving, or maintenance of the number of accumulators but now able to operate a greater number of emergency valves in a more sophisticated or advance gas liquefied gas cargo carrier.

[0015] The hydraulic pressure intensifier allows for the storage of a greater amount of hydraulic fluid at elevated pressures, which can lead to a more responsive and powerful actuation of the emergency valves. Reliability of actuation, and the expectancy of swift responsiveness, in an emergency situation, is critical when other power availability is reduced or completely absent.

[0016] By storing fluid at a pressure above atmospheric pressure (barg), the system ensures that there is always a positive pressure differential, facilitating the rapid movement of fluid to the emergency valves when activated.

[0017] The ability to store fluid at higher pressures can reduce the size of the accumulators required, leading to a more space-efficient design.

[0018] In a development, the system further comprises a pressure reducer able to reduce the pressure in the one or more hydraulic accumulators to a pressure below 150 barg. The ability to reduce pressure also provides flexibility in system design and can help in maintaining the integrity of the hydraulic system during various operational phases.

[0019] The pressure reducer can act as a safety mechanism, preventing over-pressurization of the system and protecting both the emergency valves and the hydraulic components from potential damage due to excessive pressure.

[0020] The system's capability to adjust the pressure to a specific range such as between 130 barg and 140 barg also allows for fine-tuning of the emergency valve operation, optimizing performance and reliability.

[0021] By providing a specific pressure range for operation, the system can be tailored to meet the precise requirements of different types of liquefied gas cargoes and their associated handling equipment.

[0022] The targeted pressure adjustment ensures that the hydraulic fluid is delivered at an optimal operational pressure, which can enhance the lifespan of the emergency valves by reducing wear and tear caused by inappropriate pressure levels.

[0023] There is disclosed a system wherein the emergency valves can be emergency shut down valves. Such valves are known in the art.

[0024] Specifying that the emergency valves are emergency shutdown valves clarifies the critical safety function of the system, emphasizing its role in rapidly ceasing cargo operations to prevent accidents.

[0025] The system's design, focused on emergency shutdown valves, ensures that it is optimized for the most demanding safety scenarios, providing a high level of protection for the carrier, its cargo, and the environment.

[0026] By catering specifically to emergency shutdown valves, the system can be integrated with other safety protocols and systems on the carrier, creating a comprehensive safety network that can be activated in the event of an emergency. Optionally, the hydraulic pressure intensifier creates greater useable hydraulic volume in the one or more hydraulic accumulators.

[0027] By increasing the usable hydraulic volume, the system can handle emergency demand situations more effectively, ensuring reliable performance during critical operations. The accumulator has a greater useable volume of hydraulic fluid able to be provided at the required operational pressure in an emergency situation. This increases the reliability and responsiveness of the system in a critical situation compared to a conventional drive system operating emergency valves.

[0028] Optionally, the liquefied gas cargo is one or more of the group comprising: liquefied hydrocarbons such as LPG or LNG, ethane and ethylene; as well as other liquified gases such as ammonia and carbon dioxide. Liquefied gas cargo carriers for such liquefied gases are well known in the art.

[0029] The system's versatility in handling a variety of liquefied gases, such as LPG, LNG, carbon dioxide, ammonia, and ethylene, allows for broad application across different industries.

[0030] By being compatible with multiple types of liquefied gas cargo carriers, the system reduces the need for specialized equipment for each type of liquefied gas cargo carrier emergency valve drive system, leading to cost savings in equipment investment and storage space.

[0031] Optionally, the operating pressure of the emergency valves in the liquefied gas cargo carrier is 135 barg.

[0032] Utilizing a figure of 135 barg as the operating pressure unit for emergency valves standardizes the system with common industry practices, simplifying integration with existing infrastructure and reducing the likelihood of operational errors.

[0033] The use of barg, which accounts for atmospheric pressure, provides a more accurate measure of the pressure within the system, enhancing safety and reliability during emergency situations. Optionally, the hydraulic pressure intensifier is able to store at least 10% more hydraulic fluid in the one or more hydraulic accumulators.

[0034] The ability of the hydraulic pressure intensifier to store at least 10% more hydraulic fluid in the accumulators directly translates to increased operational capacity without the need for physical enlargement of the system.

[0035] The increased storage capacity for hydraulic fluid allows the system to respond more effectively to sudden changes in demand, providing a buffer that enhances system responsiveness and stability.

[0036] With the capability to store additional hydraulic fluid, the system can potentially reduce the number of accumulators required, leading to a more compact and cost- effective design.

[0037] Optionally, the hydraulic pressure intensifier is able to store at least 20% or at least 30% or at least 40% more hydraulic fluid in the one or more hydraulic accumulators.

[0038] Storing at least 20% more hydraulic fluid in the accumulators significantly extends the operational time between refills, which is particularly beneficial in remote or inaccessible locations where maintenance opportunities are limited.

[0039] The enhanced storage capacity of the hydraulic pressure intensifier allows for better management of hydraulic energy, contributing to improved overall energy efficiency of the system.

[0040] Also disclosed is a controller for a liquefied gas cargo carrier emergency valve drive system, the controller being able to provide hydraulic fluid to emergency valves controlling the handling of a liquefied gas cargo on the carrier from one or more hydraulic accumulators having hydraulic fluid therein at a pressure above 150 barg.

[0041] The controller's ability to provide hydraulic fluid at elevated pressures ensures rapid and reliable actuation of emergency valves, which is crucial for maintaining safety and operational control in the event of an emergency. By sourcing increased pressure hydraulic fluid from the accumulators, the controller can continue to operate effectively even if the main power supply is compromised, thus enhancing the resilience of the liquefied gas cargo handling system.

[0042] The ability to control emergency valves from a centralized controller allows for streamlined operations and potentially reduces the need for manual intervention, which can be especially beneficial in hazardous or inaccessible environments.

[0043] The controller's compatibility with a range of emergency valve drive systems provides flexibility in design and application, allowing it to be integrated into various liquefied gas cargo carrier configurations.

[0044] The adaptability of the controller to work with different emergency valve drive systems in different liquefied gas cargo carriers ensures that it can be updated or modified with minimal disruption to the existing infrastructure, promoting longevity and cost-effectiveness.

[0045] The controller's design may incorporate advanced diagnostics and monitoring capabilities, which can provide real-time feedback and predictive maintenance alerts, thereby reducing downtime and enhancing safety.

[0046] According to a further aspect of the present invention, there is provided a liquefied gas cargo carrier having a liquefied gas cargo carrier valve drive system as defined herein. The integration of a valve drive system as defined in previous claims into the liquefied gas cargo carrier ensures a high level of precision and reliability in the control of gas flow, which is essential for maintaining the integrity of the cargo and the safety of the vessel. This is especially where the liquefied gas 's valve drive system may be designed to operate under extreme conditions, providing consistent performance and reducing the risk of cargo loss or environmental contamination, even in adverse maritime environments.

[0047] Embodiments of the application will now be described by way of example only, and with reference to the attached drawing Figure 1, being a schematic plan of a liquefied gas cargo carrier emergency valve drive system according to embodiments of the present invention. Figure 1 shows a liquefied gas cargo carrier emergency valve drive system 2 comprising one or more hydraulic accumulators 4 (three shown in Figure 1) configured to provide hydraulic fluid to a range of emergency shut down valves 6 (three shown in Figure 1) controlling the handling of a liquefied gas cargo such as LPG, LNG, carbon dioxide, ammonia, ethane, or ethylene on a liquefied gas cargo carrier (not shown).

[0048] The operating pressure of the emergency valve drive system 2 on a typical conventional liquefied gas cargo carrier is 135 barg.

[0049] Figure 1 also shows a hydraulic pressure intensifier 8, able to increase the pressure of hydraulic fluid to be stored in the accumulators to a pressure above 150 barg. The hydraulic fluid is either returning from the emergency shut down valves 6, or from a supply tank (not shown), or both.

[0050] Figure 1 also shows a pressure reducer 10 able to reduce the pressure in the one or more hydraulic accumulators 4 to a pressure below 150 barg, in particular to or around 135 barg.

[0051] Figure 1 shows a central controller 14 for the liquefied gas cargo carrier emergency valve drive system 2, able to control the flow of hydraulic fluid to and from one or more of the hydraulic accumulators 4 through a suitable T-valve 12.

[0052] Optionally, the hydraulic pressure intensifier 8 can increase the amount of hydraulic fluid stored in the accumulators 4 by at least 10% or 20% or 30% or 40%, so that the hydraulic accumulators 4 have more hydraulic fluid when required, and the hydraulic accumulators are able to provide a greater useable volume of hydraulic fluid to the emergency valves 6 in critical situations. By storing the hydraulic fluid at a pressure above at least 150 barg, the system 2 ensures that there is always a positive pressure differential, facilitating the rapid movement of hydraulic fluid to the emergency valves 6, either directly or indirectly, when required or otherwise activated. In particular, the incorporation of one or more hydraulic accumulators 4 able to supply hydraulic fluid in an emergency at above conventional pressure increases the useable volume of hydraulic fluid in the accumulators compared to accumulators only storing hydraulic pressure at the valve operational pressure, and therefore increases the assurity of a reliable supply of hydraulic fluid to the emergency valves, which is critical for maintaining control over the handling of liquefied gas cargo in emergency situations.

Claims

CLAIMS1. A liquefied gas cargo carrier emergency valve drive system, comprising one or more hydraulic accumulators able to provide hydraulic fluid to emergency valves controlling the handling of the liquefied gas cargo on the carrier, and a hydraulic pressure intensifier for storing the hydraulic fluid in the one or more hydraulic accumulators at a pressure above 150 barg.

2. A system as claimed in claim 1 , comprising a hydraulic pressure intensifier for storing the hydraulic fluid in the one or more hydraulic accumulators at a pressure above 200 barg.

3. A system as claimed in claim 1 or claim 2 further comprising a pressure reducer able to reduce the pressure in the one or more hydraulic accumulators to a pressure below 150 barg.

4. A system as claimed in claim 3 comprising a pressure reducer able to reduce the pressure in the one or more hydraulic accumulators to a pressure to between 135 barg and 140 barg.

5. A system as claimed in any one of the preceding claims, wherein the emergency valves are emergency shut down valves.

6. A system as claimed in any one of the preceding claims, wherein the hydraulic pressure intensifier creates greater useable hydraulic volume in the one or more hydraulic accumulators.

7. A system as claimed in any one of the preceding claims, wherein the liquefied gas cargo is one or more of the group comprising: a liquefied hydrocarbon such as LPG or LNG, ethane and ethylene, ammonia, and carbon dioxide.

8. A system as claimed in any one of the preceding claims, wherein the operating pressure of the emergency valves is 135 barg.

9. A system as claimed in any one of the preceding claims, wherein the hydraulic pressure intensifier is able to store at least 10% more hydraulic fluid in the one or more hydraulic accumulators.

10. A system as claimed in claim 9, wherein the hydraulic pressure intensifier is able to store at least 20% more hydraulic fluid in the one or more hydraulic accumulators.

11. A system as claimed in claim 10, wherein the hydraulic pressure intensifier is able to store at least 40% more hydraulic fluid in the one or more hydraulic accumulators.

12. A liquefied gas cargo carrier having a liquefied gas cargo carrier valve drive system as defined in any one of claims 1 to 10.

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