When a natural gas pipeline ruptures, the adjacent Automatic line Control Valves (ALCVs) should close quickly to prevent leakage or explosion. The differential pressure set point (DPS) at each Valve location is the main criteria for value setting in ALCV action. If the DPS is not properly adjusted, the ALCV may mistakenly close or it may not take any action at proper time. This study focused on the DPS values prediction for setting ALCV installed on a gas pipeline with 1mm orifice diameter. The effect of characteristic parameters such as pipeline operational pressure (POP) and pipeline pressure drop rate (ROD) due to rupture or major leak was experimentally investigated on DPS. Twenty-five different conditions with double set of typical mentioned characteristic parameters were chosen. For each condition, the differential pressure (DP) was measured over 180 seconds by analyzing the experimental values. Therefore, 25 maximum DP values (DPSs) were obtained. The DPS increases by increase in ROD or decreasing POP parameters. Because of using nitrogen gas instead of natural gas due to safety reasons, the DPS results can be practically applied by adding a safety factor of 15%. The diagram of DPS with respect to ROD and non-dimensional DPS (DOP) versus non-dimensional ROD (RTP) was provided for different POPs.

When a natural gas pipeline ruptures, the adjacent Automatic line Control Valves should close quickly to prevent leakage or explosion. The differential pressure set point at each Valve position has an essential role for value determining in Automatic line Control Valves action. This study focused on the differential pressure set point values prediction for setting Automatic line Control Valves installed on a gas pipeline. The effect of characteristic parameters such as pipeline operational pressure and pipeline pressure drop rate due to major leak or abrupt rupture was experimentally examined on differential pressure set point. 25 different conditions with double set of typical indicated characteristic factors were selected. The differential pressure for any unique condition was measured in 180s time duration by analyzing the experimental outcomes, statistically. The differential pressure set point increases by changing such as increase in pipeline pressure drop rate or decrease in pipeline operational pressure parameters. Due to applying nitrogen gas instead of natural gas on account of safety claiming, the differential pressure set point results practically can be implemented by adding a 15% safety coefficient. The diagram of differential pressure set point with respect to defined parameters was presented for different values of pipeline operational pressure.

Tape irrigation systems have become popular due to water resources scarcity. Uniform water distribution in such systems is of great importance. In this study the application of an Automatic discharge Control Valve is investigated in terms of water distribution uniformity of tape irrigation systems. To this end, Control Valves of the design discharges of 0. 4 and 0. 6 l/s were fabricated based on the current design methods. To study the effect of the Automatic discharge Control Valve, variations of the water distribution uniformity in tapes and laterals were estimated in some field tests. The results indicated that the uniformity coefficient increases up to 93% at the tapes’ entrance. Finally, recommendations were provided to select a reliable tape length. It was found that a pressure increase of 2. 5 times higher than the design value would result in tape failure. Therefore, correct tape length selection is of great importance to prevent any damages.

Many industries including power-plants, refineries and so on are using high pressure Control Valves. Many of these Valves have traditional geometries like butterfly Valves. Unfortunately, because of the special design of these Valves, cavitation causes very rapid corrosion. In the last decade, a next generation of Control Valves have been introduced which are designed to prevent cavitation. Because of the special fluid paths in the Labyrinth Valves, the pressure drop is very graduated which prevents cavitation. In this article, the geometry of fluid path is optimized using Taguchi method. To this end, four parameters are considered including path's height, number of corners, corner radii and input area. For each parameter three levels are assumed and using a standard Taguchi array the optimum geometry is predicted. Then the pressure drop in optimum geometry is simulated using finite element method and the results validated the optimized geometry.

This paper presents the sensitivity analysis of a sample hydraulic servo Valve. The sensitivity of the flow-current curve with respect to variations of geometrical and functional parameters is evaluated. This analysis is done by use of a model which simulates the Valve behavior in terms of geometrical parameters and properties of components. With attention to multiplicity of the Valve components and the complexity of the system, the more effective parameters have been studied more precisely. Deviation of “flow gain” And “saturation flow” -which are the main characteristics of the Valve behavior- from their nominal values in the flow-current curve, is the criterion for the Valve sensitivity assessment. The curve of characteristic variations versus parameter variations has been plotted. The evaluations indicated that all of the sensitivity curves are linear in the limited intervals. Also between the evaluated parameters, “nozzle-flapper equilibrium distance”, “orifice diameter” and “stiffness of spool spring” have more sensitivity effect on the Valve performance, respectively.

A compressor is a machine that is used to increase the pressure of various gases. How to increase the pressure depends on the compressor type. One of the functional problems of centrifugal compressors is the phenomenon of the surge, which is still an obscure and unknown phenomenon that can induce mechanical or thermal stress in the system and cause a lot of damage. This type of aerodynamic instability reduces the compression ratio at both ends of the compressor, thereby reducing the overall efficiency of the system. In general, when a surge occurs, it causes process turbulence, the degradation of overall compressor efficiency, the reduction of compressor life due to mechanical damage to seals, bearings, rotor, and impellers, and the loss of internal freedoms and sensitive mechanical parts of the system. Therefore, surge Control is one of the challenges of compressor Control and expands the operating range of compressor operation. A map compressor consists of two axes, horizontal and vertical, as well as a set of curves that show the horizontal axis of the flow (capacity) and the vertical axis, head or pressure. Compressors must change their speed to change the output flow. For each speed, there is a minimum point and a maximum flow point within which the compressor operation is stable and predictable. The maximum capacity point is called the stone wall point and the minimum capacity point is called the vertex point. The surge line (SL) of a compressor is formed by connecting the surge points at different speeds. If the compressor works on the right side of the surge line, it is in a steady state, but if it works on the left side of the surge line, it is in an unstable or surge state. Using methods based on active surge Control, the instabilities leading to the surge can be eliminated, and the area of stable performance of the system can be extended to the surge line, and thereby the stable area of the system can be widened. This paper uses a dynamic model of centrifugal compressors with a recycle Valve, as well as a proportional-integrator-derivative (PID) Controller and a sliding mode Controller, to Control the surge phenomenon with a compressor Control approach based on the surge Control line. A new sliding surface is defined for Controlling sliding mode, and it is Controlled by using recycle Valve and a compressor inlet Valve. A quadratic Lyapunov function is used to ensure the stability of the intended slip surface. The two approaches of inlet and recycle Valve are expressed individually and collectively. The results of simulation in MATLAB state that among the compressor with a PID Controller and the compressor with sliding mode, the latter outperforms the former in Controlling the compressor at different speeds. Based on the comparison of the results, the amplitude of the Control signal in the sliding mode is less than PID and the system reaches a stable state with less energy consumption, which shows better Control by the sliding mode than by PID.

In this paper a new method based on multistage fuzzy Control using intelligent ‎optimization techniques is proposed to optimize the Automatic train Control system. In ‎this method the energy function which elaborates the train power consumption is first ‎minimized by applying Kuhn Tucker conditions. As a result the switching points at ‎which the Control strategies are changed between acceleration coasting constant speed ‎and braking are determined considering the track specifications including gradients ‎and curvatures as well as the practical train model. Since in constant speed strategy ‎the energy optimization leads to infinite changes in Control inputs which is not ‎practically possible a multistage fuzzy Control based on fuzzy dynamic programming ‎with fuzzy termination time is incorporated to overcome this difficulty. Multistage ‎fuzzy Control will optimize other significant goals involving safety traceability in ‎speed and accuracy in distance and limit the number of switching among different ‎strategies. Hence the method will satisfy the practical requirements. This method ‎considers the running time between two stations as independent and Controllable ‎variables therefore the calculated strategies are very useful and appropriate for traffic ‎Control which the time regulations make a vital and important role. The simulation ‎results will demonstrate the efficiency of proposed method.‎

When a natural gas pipeline ruptures, the adjacent upstream and downstream Automatic Control Valves (ACV) should close quickly to prevent leakage or explosion. The differential pressure set point (DPS) at each Valve location is the main criteria for value setting in ACV actions. If the DPS is not properly adjusted, the ACV may mistakenly close or it may not take any actions at a proper time. In this study, the effect of characteristic parameters such as pipeline operational pressure (POP) and pipeline pressure drop rate (ROD) due to rupture or a major leak was experimentally investigated on DPS. 25 different conditions with the double set of the mentioned typical characteristic parameters were chosen. In each condition, the differential pressure (DP) was measured over a period of 180 s by statistically analyzing the experimental results, so 25 maximum DP values (DPSs) were obtained. The DPS rises by an increase in ROD or a decrease in POP. Because of using nitrogen gas instead of natural gas for safety reasons and the uncertainties, the DPS results can be practically applied by adding a safety factor of 15%. Finally, the diagram of DPS with respect to ROD and that of non-dimensional DPS (DOP) versus non-dimensional ROD (RTP) were provided for different POP’ s.