A telescoping hydraulic system is an essential component of a Tower Crane. It allows the crane to extend and retract its boom, enabling it to reach different heights and distances. This system consists of several hydraulic cylinders, valves, and hoses that work together to provide the necessary power and control.
The main hydraulic cylinder in the telescoping system is responsible for extending and retracting the boom. It is typically a double-acting cylinder, meaning it can generate force in both directions. This cylinder is connected to the base of the crane and extends vertically to support the boom. Hydraulic Pump Station,Telescoping Cage,Tower Crane Cylinder,Axial Plunger Pump,hydraulic pump unit SHEN YANG BAOQUAN BUSINESS CO., LTD , https://www.syconstructionhoist.com
Key words: cryogenic valve; LNGV; gas station; check valve Abstract:Introduced the note of the lectotype, installation, construction and the solution of the common fault of low temperature valves, which are used in LNGV filling station project. Offer the effect references for the craft, construction & maintaination of the LNGV filling station project.
Key words: low temperature valve; liquefied natural gas vehicle; filling station; check valve
LNG has the characteristics of small size, multiple gas sources, flexibility, long distance, non-pipeline and cleaner, and more value for use. However, LNG is a low-temperature medium. In the design and construction process of low-temperature field stations such as LNGV gas filling stations, the selection of low-temperature valves and pipeline construction should consider the structural characteristics of the medium and the valve itself under the premise of complying with the standard specifications. Discuss it.
1 Selection and construction of low-temperature shut-off valve As one of the most commonly used valves on low-temperature pipelines, low-temperature shut-off valves are mainly divided into low-temperature long-handle shut-off valves and short-handle shut-off valves. Short-handle valve is generally used at -100 °C. If the temperature is lower than -130 °C, the PTFE filler will freeze or freeze. The temperature range of LNG in the project is generally -120 °C ~ -140 °C. Therefore, the short stem cutoff Valves are typically used in low temperature gas phase lines.
2 Pneumatic emergency shut-off valve selection and construction Pneumatic emergency shut-off valve, also known as pneumatic ball valve, its function is to control the cutting and closing of the fluid in the process pipeline, consisting of a spring pneumatic diaphragm actuator or a floating piston actuator and a regulating valve. Receive signals to adjust the meter. The opening and closing member is opened or closed by the force of the cylinder. Pneumatic emergency shut-off valve is divided into single drive air source and dual drive air source. During installation, the pneumatic emergency shut-off valve has its own structure and use characteristics. In addition, the shut-off valve should manually rotate the handwheel to the minimum before using the air source. It is off), and in other cases, manual can be used under emergency.
The following faults may occur in the emergency shut-off valve: 1 damage to the sealing surface of the valve disc - the cause of damage to the sealing surface of the valve disc is: before the equipment is commissioned, the pipeline is not blown off, so that the welded scale remains in the pipeline. Impurities. The prevention method is to thoroughly blow out the pipeline before commissioning; 2 The cause of leakage inside the medium-media leakage is: the sealing surface is damaged, and the impurities are trapped. The treatment method: repairing the sealing surface and cleaning impurities can prevent internal leakage; 3 packing damage - the packing damage will leak, tighten the packing compression nut, if it is leaky, replace the packing PTFE; 4 cylinder does not work - check whether the air source pressure is correct, check whether the cylinder piston is issued (whether there is impurities inside the cylinder), Inspect the piston O-ring for damage.
3 check valve (check valve)
Check valves, also known as check valves or check valves, are designed to prevent backflow of media in the line. According to the structure, it can be divided into three types: lift check valve, swing check valve and butterfly check valve: lift check valve can be divided into vertical and horizontal; swing check valve It is divided into three types: single-lobed, double-petal and multi-lobed; the butterfly check valve is straight-through. The swing-type check valve has a streamlined shape in the valve passage, and the flow resistance is smaller than that of the lift check valve. It is suitable for large-caliber occasions where the flow rate and flow are not constantly changing, and the sealing performance is not as good as that of the lifting type; The check valve has a simple structure and can only be installed on a horizontal pipe with poor sealing performance. The check valve of the lift check valve slides along the vertical center line of the valve body. The lift check valve can only be installed on the horizontal pipe. On the high pressure small diameter check valve, the valve can adopt the ball, lifting type. The check valve has a large fluid resistance coefficient. Because the LNGV filling station has high requirements for flow control and detection of LNG medium and valve sealing performance, the welding type lift check valve is selected.
Like LNG, an easily gasified low-temperature medium, the medium pressure before and after the check valve is easily close to equilibrium and “saw-sawed†with each other. Therefore, in addition to keeping the pipeline cold, it is also necessary to select the check valve. The process diameter takes into account the actual operating conditions and media characteristics.
4 Safety Valves Because the safety valve can operate without any external energy source, it is often used as the last protection device for pressurized equipment. The function of the safety valve cannot be replaced by other protective devices. Due to the special function of the safety valve, the requirements for its performance are determined: the necessary sealing; reliable opening; stable discharge; timely closing; sealing after closing. The Code for Design and Construction of Refueling Stations GB50156-2012 stipulates that the release of various safety valves of LNG filling stations should be concentrated to the safe area.
5 Other low temperature valves such as low temperature instrument valves, back pressure valves, etc. will be used in other LNG filling stations. Pay attention to the characteristics of the medium used and the structure and performance of the valve itself during design selection and on-site construction. Features. In addition, after the completion of the construction of the entire station area, in order to ensure the smooth operation of the entire project pipeline and the key components connected to the pipeline, such as pumps, cryogenic valves, flowmeters, and the measurement accuracy of the LNG dispenser itself, it should be before the test run. Thoroughly purge the valves and accessories in the entire pipeline and piping.
6 Conclusion It can be seen that the application requirements of cryogenic valves are higher than those in other common projects, whether it is in the process design, selection, or on-site construction and acceptance, professional, dedicated and meticulous.
About the Author:
Wang is busy (1982-), female, Shandong Yucheng, engineer, master, engaged in gas equipment development research work.
To control the movement of the hydraulic cylinder, various valves are used. These valves regulate the flow of hydraulic fluid into and out of the cylinder, allowing for precise control of the boom's extension and retraction. The valves are typically operated by the crane operator using a control panel or joystick.
The hydraulic system also includes hoses that connect the cylinders and valves. These hoses transport the hydraulic fluid, which is typically oil, between the different components. The hoses must be durable and able to withstand high pressure to ensure the safe and efficient operation of the crane.
In addition to the main hydraulic cylinder, there may be secondary cylinders in the telescoping system that provide additional support and stability to the boom. These cylinders are typically smaller and are used to fine-tune the position and angle of the boom.
Abstract: This paper introduces the selection, installation, construction precautions and common fault resolution methods of low temperature valves in LNGV gas station project, and provides effective reference for the process, construction and maintenance of LNGV gas station project.