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Valve Requirements
Published in Tony Giampaolo, Compressor Handbook, 2020
Valves have numerous uses in every compressor application. In general these include process control, isolation and safety. The process control valve is used to regulate or control the flow, pressure and temperature of the system. The valves that best perform this function are the ball valve, butterfly valve and globe valve.The isolation valve is used to “shut in” a compressor. This is necessary in order to perform maintenance on the compressor. The valves that best perform this function are the gate valve, knife valve and plug valve.The safety valve is used to protect the compressor and personnel in the area. It is always either automatically activated or is controlled to activate in response to a critical condition. The valves that best perform this function are pressure relief valves and check valves.
Control valves
Published in Raymond F. Gardner, Introduction to Plant Automation and Controls, 2020
Control valves are devices that modulate flow rate, pressure, temperature, or level. These are final control devices and understanding their operation, nuances, and options is important for integrating them into control systems. Control valves range from the self-contained, self-actuated devices to the externally powered, pilot-actuated remote-sensing devices. The separately powered systems can be entirely pneumatic-control systems, or they may use electronic controls interfaced with pneumatic or electrically powered actuators, which are much more conducive to large devices using remote-sensing and control. Proper sizing of the control valve and selection of its flow characteristics is important for long reliable operation. Typical plant applications include: Pressure-reducing valvesBack-pressure regulatorsPressure-switching devicesPressure-relief or vacuum breakersLow-level makeup or high-level dumpFlow regulation or flow bypass for temperature control
Heat Exchangers
Published in Béla G. Lipták, Optimization of Industrial Unit Processes, 2020
Misalignment or distortion in a control valve installation can cause binding, leakage at the seats, dead band, and packing friction. Such conditions commonly arise as a result of high-temperature service on three-way valves. The valve, having been installed at ambient conditions and rigidly connected at three flanges, cannot accommodate pipeline expansion because of high process temperature, and therefore distortion can result. Similarly, in mixing applications, when the temperature difference between the two ports is substantial, the resulting differential expansion can also cause distortion. For these reasons, the use of three-way valves at temperatures above 500°F (260°C) or at differential temperatures exceeding 300°F (167°C) is not recommended.
Trends in hydraulic actuators and components in legged and tough robots: a review
Published in Advanced Robotics, 2018
Koichi Suzumori, Ahmad Athif Faudzi
There are many types of hydraulic valves that act as the component to control the flow of the fluid. Basic valves include pressure control valves, directional control valves, and flow control valves [40]. Modular valve is normally compact with its pipe-less structure while logic valves are used for high-flow and high-pressure application such as in steel mill application and large-scale pressing machine. Proportional electro hydraulic valve is used to control analog switch on the hydraulic power unit [71]. Mobile tough robots, such as BigDog [126], HyQ [88], robotic leg [127], TaeMu robot [128], and others, use new actuators that combine the servo valves together with hydraulic cylinder in a single structure. TaeMu robot [128] and robotic leg [127] uses PSC Co. Ltd. servo valve that weighs 300 g. The servo valve has flow capacity of 8.4 l/min (0.00014 m3/s) at 7 MPa pressure drop, with frequency response of 120 Hz at −3 dB and 90 phase lag for ±25% input. HyQ and Boston Dynamic robots such as BigDog used Moog valves to control the actuators. The system uses two stage valve normally applied for torque motor and nozzle flapper type, both systems can control for maximum 21 MPa pressure. In a joint research, Tokyo Tech. and Yuken Kogyo. Co are currently developing a new servo valve for low flow of 4.02 l/min (0.000067 m3/s) and high pressure of 35 MPa with small design, high response, proportional 20 Hz, servo 200, 300 Hz.
The flow and cavitation characteristics of cage-type control valves
Published in Engineering Applications of Computational Fluid Mechanics, 2021
Zhi-xin Gao, Yang Yue, Jia-yi Wu, Jun-ye Li, Hui Wu, Zhi-jiang Jin
Control valves are key components used to regulate flow and pressure in many process industries, such as the nuclear power and thermal power stations. Usually, the volume flow rate of control valves increases monotonously as the pressure drop between the valve inlet and the valve outlet increases, but a choked flow appears when the pressure drop is large. For incompressible working fluid, cavitation or flashing phenomenon is the main reason for choked flow, which can eventually result in valve vibration, noise, or even valve damage.
Experimental investigation and heat transfer process on longitudinal fins with different notch configuration
Published in International Journal of Ambient Energy, 2018
The experimental set-up (Figure 1) consists mainly of a nozzle, the test section, a flow control valve and a blower. The single point temperature indicator is used to measure the fin temperature, base plate temperature, and inlet and exit temperature of the air. A dimmer stat with digital multi meter and analog ammeter is used to control the electric current supplied to the heater plate. The test section is a rectangular duct heated at the bottom with a cross-section 140 mm in width and 60 mm in height. The bottom of the heater is wounded with asbestos thread. The unheated entrance region of the duct is 190 mm, the heated test section involving an aluminium plate and rectangular longitudinal fins is 127 mm and heated exit region pipe diameter is 25.4 mm. At the channel entrance, a nozzle is made of 1-mm-thick galvanised iron sheet. The test section consists of a 190 × 110 × 1 mm3 aluminium plate, aluminium longitudinal fins of 1 mm thickness and 127 mm in width and 30 mm height with triangular notch and circular at the centre of the fin with 20% notch area. Fins are attached to the plate by taken the slots and paste the fins using the araldite epoxy adhesive. The thermocouples are attached to fins to measure the fin temperature and to the base plate to measure the base plate temperature. All surfaces are carefully cleaned and polished. A plate heater was placed under the mild steel plate, with a size equal to the size of the aluminium plate having dimensions of 190 × 110 mm2. Electric current was provided to the heater plate via a variac, providing a heat flux boundary condition specified for a decide experimental case. The test section of the rectangular duct is insulated with asbestos thread and was mounted on rigid supporting frame. The test section is attached to a blower through a flow control valve. A control valve is used to control the flow rate (Agrawal and Bhavsar 1977). The air velocity is measured with a vane probe anemometer. All the thermocouples were attached to the fins by drilling a hole in the fins and connecting them with rigidity. The data should be collected for different watts, voltage drop across heater, and electric current. Using these different values collecting from the experiment, the following parameter has to be determined. The Nusselt number for the bottom plate and the heat transfer coefficient (h) has to be calculated.