Overpressure protection system on filling with gas or cryogenic liquid and mode of operation

Abstract

An overpressure protection device for filling gas or cryogenic liquid to make the supply of gas or cryogenic liquid between a cistern and a cryogenic tank safer and more efficient. It is provided with

Description

"OVERPRESSURE PROTECTION SYSTEM ON FILLING WITH GAS OR CRYOGENIC LIQUID AND MODE OF OPERATION" Technical domain The overpressure protection device is a complete unit developed to protect tanks (mostly cryogenic) from overfilling during the filling phase by automatically closing the line when a set pressure is reached, using mechanical energy only. For example, in the process of filling a tank with liquefied gas through a cistern, it is very important to avoid any overfilling that could lead to dangerous situations such as rupture of the tank. This system is considered to be safety equipment, category PED IV, in accordance with the terms of European Directive 2014 / 68 / EU State of the art There is a system on the market that performs overpressure protection, but on linear valves. It is based on the use of a safety valve which, when activated, releases a trigger, activating a linear spring in the valve, closing the passage circuit. The existing solution is applicable to linear valves, such as globe valves. The solution subject of the invention, however, is applicable to 90° valves, such as floating ball valves . The solution provided by the invention offers significant advantages over the existing solution: 1. On the flow rate / pressure drop level: the existing types of valves have a geometry that induces significant pressure drop, reducing the flow rate capacity, increasing the filling time of the tanks; on the contrary, the invention uses a type of valve that almost does not affect the line since its interior is similar to a simple pipe, allowing high flow rates and low pressure drop. This is an enormous advantage for decreasing the filling time of the tanks; 2. Furthermore, the existing solutions are not provided with a secondary line for pressure relief, unlike the invention, which provides a secondary line to prevent overpressure due to thermal expansion of fluid that may be trapped between the valve and the tank after automatic closure of the protection system; 3. At the level of the resetting system: the current solution is a complex one that needs to be coupled to the safety valve to release the internal pressure and reposition it in the open position. Differently, in the invention the internal pressure of the cylinder is released by opening the needle valve of the exhaust line . The system is reset with a master key, rotating the central axis of the valve by 90°, opening the valve and pre-loading the spring return actuator; 4. In terms of improper opening and vibration, where the current solution has a high degree of constraint, while the invention has a mechanically stable trigger system and the safe position is only possible by pressurising the single-acting cylinder via the pilot controlled valve; 5. With regard to sealing capacity, ball valves, such as that of the invention, ensure better sealing capacity than globe valves. This is because the ball is pressurised against the seats, providing better sealing capacity; 6. Whereas the state of the art uses a safety valve as a pressure sensor, the invention features a pilot controlled valve; 7. Finally, as regards pressure monitoring, the invention is equipped with pressure gauges for monitoring the pressure in the filling process. Moreover, the invention is a completely autonomous device, not relying on any external electrical, pneumatic or hydraulic system in order to maximise safety against possible self-ignition or other forms of danger. Description of the figures Figure 1 represents the filling device with the protection system covered by the invention, in front section, showing the cryogenic ball valve (1), the pilot controlled valve (4) the needle valve (6) and two pressure gauge units (7), one placed before and one after the pilot controlled valve, the hydraulic hose of the secondary line (11) and the relief pipe (12), as well as the housing (13); Figure 2 displays the filling device with the protection system covered by the invention, in cross section, highlighting the cryogenic ball valve (1), the spring return actuator (2) , the safety valve (5) and the connection support (10), the hydraulic hose of the secondary line (11) and the relief pipe (12), as well as the housing (13); Figure 3 features the cryogenic valve (1), the pilot controlled valve (4), the needle valve (6), the pressure gauge (7) close to the pilot controlled valve, the connection support (10) and the relief pipe (12), as well as the housing (13), in perspective; Figure 4 represents the spring return actuator (2), in side view and in section, equipped with a single-acting cylinder (3) and a trigger (9); Figure 5 displays the axis of rotation (8) inside the spring return actuator (2) and the connecting bracket (10), in section, highlighting the trigger (9) and the single-acting cylinder (3); Figure 6 illustrates the inside of the connecting bracket (10), highlighting the trigger (9) and the single-acting cylinder (3) in section and in perspective - and in more detail; Figure 7 represents the cryogenic ball valve (1) in detail; Figure 8 illustrates the spring-return actuator (2) in perspective and in detail; Figure 9 represents the single-acting cylinder and the trigger (9) in detail and in perspective; Figure 10 represents the pilot controlled valve 4) in detail and in perspective; Figure 11 represents the safety valve, in detail and in perspective (5); Figure 12 illustrates the needle valve (6) in detail and in perspective; Figure 13 displays the positioning (A) of the invention's protection system in a filling situation, in flowchart form, showing the cryogenic ball valve (1) and the safety valve (5), the cistern (14) and the cryogenic tank (15); Figure 14 illustrates the protection system of the invention, in flowchart form, displaying the positioning of the cryogenic ball valve (1), the spring return actuator (2) and the pilot controlled valve (4), the two needle valve units (6) and the two pressure gauge units (7), one placed before and the other placed after the pilot controlled valve (4); Description of the invention The system consists of the following components, as defined in the instrumentation and piping diagram: - The cryogenic ball valve (1), which is used to fill the tank and to control the process of opening and closing the line (Fig. 13) ; - The spring return actuator (2), which is used in the spring return function, storing energy to mechanically close the valve in a safe position when the trigger (9) is released. The system is reset by means of a master key, allowing only authorised persons to perform the task; - The single-acting cylinder (3) , which is used for the trigger function (9) and is connected to the pilot controlled valve (4) and the trigger (9). When the cylinder retracts, the trigger mechanism (9), which is under tension, is released, activating the spring return actuator (2); - The pilot controlled valve (4), which is used to activate the single-acting cylinder (3) when the safety pressure is reached. This valve is connected between the filling line and the chamber of the single-acting cylinder (3); - The safety valve (5), which is used to release any fluid trapped between the valve and the cryogenic tank (15) after emergency shut-off, to prevent any rupture due to the phase change of the fluid, which can increase the pressure. This valve is connected to the valve body; - Two needle valve units (6), used to control the opening and closing of two different lines. One is placed between the pilot controlled valve (4) and the single-acting cylinder (3) and is normally closed. When the pilot controlled valve (4) opens, the chamber of the single-acting cylinder (3) is pressurised. To reactivate the system, said cylinder must be depressurised by means of the needle valve (6), resetting the position of the single-acting cylinder (3) . The other needle valve (3) , normally closed, opens a secondary line for the purpose of carrying out functional tests . The cryogenic ball valve (1) connects the cistern feeder system (14) to the cryogenic tank (15) which is to be filled; - The spring return actuator (2) is activated by the trigger (9) and causes the cryogenic ball valve (1) to actuate when the trigger is pulled; - The single-acting cylinder (3), connected to the trigger (9), receives the pressure signal from the pilot controlled valve (4); - The pilot controlled valve is connected downstream to receive the pressure signal from the cryogenic tank (15) and communicates with the single-acting cylinder (3); - The safety valve is connected downstream, to the cryogenic ball valve body (1); - The needle valve (6) of the test line is connected to a test port and the pilot controlled valve (4). Another needle valve (6) is connected to the pilot controlled valve (4) and the single-acting cylinder. The system is activated manually by means of a key lever which preloads the springs of the spring-return actuator (2) - potential force. At the end of the stroke, the trigger (9) passes through the end piece of the single-acting cylinder (3) which springs back to allow the trigger to pass. The trigger (9) locks the spring return actuator (2) in this position . The opening of the system will occur when the singleacting cylinder (3) recedes by action of pre-set pressure input (indicatively, 2 bar) in its cavity. The protection device covered by the invention is totally autonomous, not relying on any external electrical, pneumatic or hydraulic system. It thus maximises safety against possible self-ignition or other forms of danger. Description of the security function The overpressure protection system shall be installed in the open position between the supply cistern (14) and the cryogenic tank (15) to be filled. The safety system will only act in the event of overfilling, forcing the cryogenic ball valve (1) to close the circuit; The cistern (14) supplies the cryogenic tank (15) and both the pilot controlled valve (4) and the safety valve (5) are pressurised. In the event of overfilling, i.e. overpressure, the pilot controlled valve (4) opens and releases the excess pressure, starting the filling of the chamber of the single^ acting cylinder (3) with gas; This action will force the cylinder piston to move, releasing the trigger (9), causing the spring return actuator (2) to turn the valve to the closed position, stopping the filling process; The device can be manually reset using a specific key, putting the valve in the open position and the system precharged; A second line, connected with the safety valve (5), is used to release fluid trapped between the cryogenic tank (15) and the cryogenic ball valve (1), in case thermal expansion occurs. The device is connected to the cistern (14) and the filling of the cryogenic tank (15) is started. If an overfill / overpressure occurs (due to operator distraction or otherwise), the, indicatively, 2 bar will be reached. The pilot valve (4) is calibrated to the indicative target pressure of 2 bar, and opens, allowing the singleacting cylinder (3) to be filled. The single-acting cylinder (3) retracts and the spring return actuator (2) is released and forces the cryogenic valve (1) to close, stopping filling. Once the problem is resolved, the device can be reset, restarting the filling process of the next cryogenic tank (15) . In the downstream line, residual fluid can remain in the pipework. The relief line, in the event of cryogenic liquid evaporation, may expand and cause a rupture. To avoid this, a safety valve (5), indicatively calibrated at 4 bar, will relieve any overpressure which may occur. In the event of a generalised failure, the discs of the cryogenic tank will rupture, safely rendering it unusable. Porto, 31 May 2022

Claims

1. Overpressure protection device for filling with cryogenic gas or liquid, and operating mode, characterised by a cryogenic ball valve (1) placed in the supply system between the cistern (14) and the cryogenic tank (15), a spring return actuator (2) storing the closing energy of the valve a single-acting cylinder (3) connected to the pilot valve (4) and the trigger (9), a pilot valve (4) for activating the single-acting cylinder (3), a safety valve (5) for releasing pressure, and two needle valve units (6), one placed between the pilot controlled valve (4) and the single-acting cylinder (3), and the other in a secondary pressure relief line.

2. Operation of the overpressure protection device when filling with gas or cryogenic liquid of claim 1, characterised by including, as stages or procedures:a) the connection, through the cryogenic ball valve (1) between the cistern's supply system (14) and the cryogenic tank (15) which is to be filled;b) actuation of the cryogenic ball valve (1) when the trigger (9) of the spring return actuator (2) is pulled;c) the single-acting cylinder (3) , connected to the trigger (9), receives the pressure signal from the pilot controlled valve (4);d) the pilot controlled valve (4), connected downstream to receive the pressure signal from the cryogenic tank (12), communicates with the single acting cylinder (3);e) the safety valve (5) is connected downstream, to the cryogenic ball valve body (1);f) the needle valve (6) of the test line is connected to a test port and the pilot valve ¢4) and the other needle valve (6) is connected to the pilot valve (4) and the single acting cylinder (3);g) The device is connected to the cistern (14) and the filling of the cryogenic tank (15) is started.

3. Operation of the overpressure protection device when filling with gas or cryogenic liquid, in accordance with the previous claim, characterised by being provided with a safety function contemplating, as procedures:a) the need for the protection device to be installed in the open position, between the supply cistern (14) and the cryogenic tank (15) to be filled;b) the protective device can only be triggered safely in the event of overfilling, in which case the cryogenic ball valve (1) is forced to close the circuit;c) the cistern (11) is filled and the pilot valve (4) and the safety valve (5) are pressurised;d) in the event of overfilling (overpressure), the pilot controlled valve (4) opens and releases the excess pressure, initiating the filling of the chamber of the single-acting cylinder (3) with gas;e) filling the cylinder chamber with gas forces the piston of the single acting cylinder (3) to move, releasing the trigger (9) and causing the spring return actuator (2) to turn the valve to the closed position, stopping the filling process;f) the device can be manually reset by placing the valve in the open position and the device pre-charged;g) there is a second line, connected to the safety valve (5) , used to release fluid trapped between the cryogenic tank (15) and the cryogenic ball valve (1) in the event of thermal expansion.

4. Overpressure protection device for filling with gas or cryogenic liquid and operating mode, in accordance with the preceding claims, characterised by not using any external electrical, pneumatic or hydraulic system.Porto, 31 May 2022.

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