Reliability and Availability Prediction of Main Stop Valve and Control Valve Systems of Steam Turbines

2011 ◽  
Author(s):  
Jinyuan Shi ◽  
Yong Wang ◽  
Xiaoping Zhong ◽  
Zhicheng Deng
Keyword(s):  
Prediction Method ◽  
Control Valve ◽  
Design Stage ◽  
Steam Turbines ◽  
Stop Valve ◽  
Control Valves ◽  
Reliability Block Diagrams ◽  
And Control ◽  
The Mathematical Model ◽  
Reliability And Availability

A method for the reliability and the availability prediction of main stop valve and control valve systems of steam turbines is presented. The calculation models for the reliability and the availability of series, parallel and series-parallel systems of main stop valves and control valves are introduced. The reliability block diagrams, the availability block diagrams, formulas for the reliability prediction and the availability prediction of systems with 2 main stop valves and 2 control valves, 2 main stop valves and 4 control valves, 2 main stop valves and 6 control valves, 4 main stop valves and 4 control valves are given together with some examples. The mathematical model for the reliability and the availability prediction method of main stop valve and control valve systems of steam turbine is simple and the physical meaning is definite. The reliability and availability of main stop valve and control valve systems can be quantitatively already calculated and improved during the design stage. A basis is thus provided for the reliability and the availability design of main stop valve and control valve systems of steam turbines.

An Approximate Method for Cross Curves of Cargo Vessels

2001 ◽  
Vol 38 (02) ◽  
pp. 92-94
Author(s):  
Huseyin Yilmaz ◽  
Mesut Giiner
Keyword(s):  
Prediction Method ◽  
Design Stage ◽  
Series Data ◽  
Design Parameters ◽  
Preliminary Design ◽  
Hull Form ◽  
Beam Depth ◽  
Preliminary Design Stage ◽  
The Mathematical Model ◽  
Load Conditions

In this study, a formula is presented to estimate cross curves of cargo vessels and to predict statical stability at the preliminary design stage of the vessel. The predictive technique is obtained by regression analysis of systematically varied cargo vessel series data. In order to achieve this procedure, some cargo vessel forms are generated using Series-60. The mathematical model in this predictive technique is constructed as a function of design parameters such as length, beam, depth, draft, and block coefficient. The prediction method developed in this work can also be used to determine the effect of specific hull form parameters and the load conditions on stability of cargo vessels. The present method is applied to a cargo vessel and then the results of the actual ship are compared with those of regression values.

Control Valves: System Flow Characteristics and Controllability

1972 ◽  
Vol 5 (5) ◽  
pp. 181-187 ◽  
Author(s):  
D M Bishop
Keyword(s):  
Theoretical Basis ◽  
Flow Characteristics ◽  
Control Valve ◽  
Design Stage ◽  
Control Valves ◽  
Theoretical Examination ◽  
System Flow ◽  
Valve Size ◽  
The Relationship

A theoretical examination is made of the relationship between a control valve and the plant in which it is installed; the effect of valve size and characteristic on the relationship is described. From the theoretical basis, practical rules are devised for use at the design stage, also for later changes that may be necessary once the plant is in operation. Some well known practical difficulties are described, together with means of evading or overcoming them.

Investigation on Flow Characteristics and Stability of Control Valves for Steam Turbines

2008 ◽  
Author(s):  
Guanwei Liu ◽  
Shunsen Wang ◽  
Hui Guo ◽  
Jingru Mao ◽  
Zhenping Feng ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Pressure Ratio ◽  
Control Valve ◽  
Operating Conditions ◽  
Flow Coefficient ◽  
Outlet Section ◽  
Steam Turbines ◽  
Control Valves ◽  
Structure Of Flow ◽  
Valve Disc

Through-flow capability and flow stability of some steam turbine control valves were studied by experimental investigation and numerical simulation. Based on the analysis of thermodynamic process in control valve, the relationship of flow coefficient, area ratio of valve outlet section to seat diameter section, pressure ratio and total pressure loss coefficient was deduced, and the expression of polytropic exponent was obtained. The relative deviations between formula results and experimental results are within 3%. Both expressions can be used for design and optimization to determine control valve parameters quantitatively. The results of 3D numerical simulation indicate that the topological structure of flow fields in all control valves is similar. The results of valve stability show that the airflow force acted on the valve disc depends on the vortex strength of flow around valve stem bush and valve disc, the asymmetric transonic impinging jet under the valve disc and the diffusing action. The valve operates steadily when the inlet and outlet Mach number are less than 0.15. As the unload degree is about 85%, stem vibrates at the operating conditions when pressure ratio is less than 0.8 and opening ratio is from 10% to 18%. A multihole annular orifice can make flow steady at all operating conditions.

scholarly journals Assessment of Residual Service Life of Cast Bodies of Control Valves of 220 MW Power Units

2020 ◽  
Vol 23 (4) ◽  
pp. 22-28
Author(s):  
Olha Yu. Chernousenko ◽  
◽  
Dmytro V. Ryndiuk ◽  
Vitalii A. Peshko ◽  
◽  
...  
Keyword(s):  
Service Life ◽  
Control Valve ◽  
Steam Turbines ◽  
Operating Life ◽  
Control Valves ◽  
Intermediate Pressure ◽  
Operating Modes ◽  
Residual Operating Life ◽  
Start Ups ◽  
Total Damage

In the regulatory documents of the Ministry of Energy and Coal Industry of Ukraine, the beyond-design operating life of the high-energy equipment of 220 MW power units is limited to the operating life of 220 thousand hours and 800 start-ups. To date, the high-temperature cast bodies of the control valves for the high- and intermediate-pressure cylinders of the K-200-130 200 MW steam turbines of DTEK Lugansk TPP have operated about 305–330 thousand hours with the total number of start-ups from 1438 to 1704, which exceeded the beyond-design service life characteristics. Therefore, it is necessary to assess the residual operating life of the control valve bodies of the high- and intermediate-pressure cylinders of K-200-130 steam turbines in order to determine the possibility of their further operation. These calculations were carried out on the basis of our earlier studies of the thermal and stress-strain states of cast turbine equipment. This paper establishes the values of stress intensity amplitudes, the values having been reduced to a symmetric loading cycle for the most typical variable operating modes. Using the experimental low-cycle fatigue curves for the 15Kh1M1FL steel, we established the values of the permissible number of start-ups and the cyclic damage accumulated in the base metal. We also determined the value of the static damage accumulated in the course of stationary operating modes according to our previously obtained experimental data on the long-term strength of the 15Kh1M1FL steel. The calculations showed that the total damage to the control valve bodies of the K-200-130 steam turbine of power unit 15 of DTEK Lugansk TPP is 97 and 98%. The residual operating life of the metal of the control valves of high-pressure cylinders is practically exhausted, being equal to 10 thousand hours. The residual life of the control valves of intermediate- pressure cylinders is 7 thousand hours, i.e. it is also practically exhausted, with safety factors for the number of cycles and strains at the level of 5 and 1.5, as well as the permissible 370,000 operating hours of the metal. With an increase in the permissible operating life of the metal to 470 thousand hours, according to experimental studies of Igor Sikorsky KPI, the total damage to the metal of cast valve bodies is reduced to 80%, and the residual metal life increases to 79,000 h and 75,000 h for the control valves of the high- and intermediate-pressure cylinders, respectively.

scholarly journals Valve Location Method for Evaluating Drain Efficiency in Water Transmission Pipelines

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2759
Author(s):  
Byoung-Ho Shin ◽  
Doo Yong Choi ◽  
Kwansue Jung ◽  
Zong Woo Geem
Keyword(s):  
Time Integration ◽  
Control Valve ◽  
Bulk Water ◽  
Water Supply Systems ◽  
Control Valves ◽  
Gravitational Flow ◽  
Drainage Time ◽  
Water Transmission ◽  
And Control ◽  
Transmission Pipelines

Water transmission pipelines, which transport bulk water into storage facilities, usually have a tree-type configuration with large dimensions; thus, the breakage of a pipeline may cause a catastrophic service interruption to customers. Although drain efficiency is closely related to the number of washout and control valves and their locations, there is no useful guideline. This paper proposes a valve locating method by introducing numerical analyses to enumerate drainage time and zone. A time integration method, combined with the Newton–Raphson algorithm, is suggested to resolve drainage time, while considering the friction loss in gravitational flow. A drain direction matrix, which shows drain direction and coverage, is derived using a network searching algorithm. Furthermore, a feasible practical approach is presented by introducing a critical horizontal slope, a major washout valve, drainage indices, and control valve embedment. The developed method is first applied to simple pipes to validate the drainage time module. Subsequently, the model is expanded to the CY transmission line, which is one of the BR water supply systems in South Korea currently in operation. The results reveal that three drain valve locations have been neglected, and the addition of control valves guarantees consistent drain time below the operational criteria.

Flow-induced vibration and noise in control valve

2015 ◽  
Vol 229 (18) ◽  
pp. 3368-3377 ◽  
Author(s):  
Li-fei Zeng ◽  
Guan-wei Liu ◽  
Jing-ru Mao ◽  
Shun-sen Wang ◽  
Qi Yuan ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Pattern ◽  
Annular Flow ◽  
Pressure Ratio ◽  
Pressure Fluctuations ◽  
Control Valve ◽  
Steam Turbines ◽  
Core Flow ◽  
Control Valves ◽  
The Core

Control valves are used as flow regulators for steam turbines, which operate under wide ranges of valve openings and pressure ratios. The inherent throttling action and complex 3D flow in control valves result in vibration and intolerable noise at small and medium valve openings. The vibration and noise clearly are firmly with the flow pattern. Experiments and numerical simulation are the primary means of determining the mechanisms. In this paper, a phenomenon of sound mutation in control valve was experimentally observed by continuously changing the pressure ratio. This phenomenon is explained for the first time. Different noise and pressure fluctuations can appear even under the same condition, depending on the process of changing the pressure ratio. A method of continuously changing the pressure ratio was used in the unsteady numerical simulation to reveal the mechanism. The results show that sound mutation occurs due to the change of annular flow and core flow. The annular flow has a lower noise and a more stable flow pattern than the core flow. Sound mutation can be used as a simple way of determining the ranges of the core flow and the annular flow.

Verification of Combined Main Steam Valve Pressure Distribution and Vibration Characteristics With Downscale Model Test on Air Condition

2019 ◽  
Author(s):  
Fumiyuki Suzuki ◽  
Shingo Nishida ◽  
Shinji Fukao ◽  
Megumu Tsuruta
Keyword(s):  
Pressure Distribution ◽  
Model Test ◽  
Pressure Fluctuation ◽  
Pressure Loss ◽  
Pressure Ratio ◽  
Control Valve ◽  
Experimental Result ◽  
Stop Valve ◽  
Main Steam ◽  
And Control

Abstract In order to enhance the efficiency and reduce the manufacturing cost of steam turbine, combined main steam valve consisting of main stop valve and control valve in the same casing has been developed. Combined main steam valve with improved flow path at internal structure will reduce pressure loss. A downscale model test on air condition was conducted to verify pressure distribution characteristics. Experimental result and numerical result obtained by computational fluid dynamics (CFD) showed reasonable agreement in pressure loss and static pressure at each flow point within the design operation range. Main stop valve (SV) and control valve (CV) vibration characteristics tests were performed simultaneously for the stability verification of governing operation from start up to full load. We confirmed that CV aerodynamic added damping ratio was positive under all measured condition of CV stroke and pressure ratio, and self-excited vibration was not generated. We also confirmed that pressure fluctuation acting on main stop valve body was sufficiently small within the operation range. Meanwhile, in the case where pressure ratio or CV stroke deviated from the operation range, pressure fluctuation around main stop valve increased. Based on CFD result and detailed analysis of experimental result, it was found that steam flow along valve seat separates periodically, which revealed the mechanism of increasing pressure fluctuation around main stop valve. By reflecting on these results, the reliability of new combined main steam valve has substantially been enhanced.

Reviewing Cyclonic Low-Shear Choke and Control Valve Field Experiences

2021 ◽  
pp. 1-16
Author(s):  
Trygve Husveg ◽  
Rune Husveg ◽  
Niels van Teeffelen ◽  
Robert Verwey ◽  
Peter Guinee
Keyword(s):  
Produced Water ◽  
Separation Efficiency ◽  
Environmental Influence ◽  
Water Concentration ◽  
Control Valve ◽  
Third Party ◽  
Control Valves ◽  
Oil In Water ◽  
And Control ◽  
Low Shear

Summary In hydrocarbon production and processing, choke and control valves mix and emulsify petroleum phases. The consequence is often that the efficiency of separation processes is affected and finally that the quality of oil and water phases is degraded. Over the last few years, low-shear valves targeting petroleum processes have emerged on the market. This paper presents four separate live-fluid experiences from low-shear valve installations, each surveyed and documented by an independent third party. Three of the installations refer to choke valves, whereas the fourth installation refers to a control valve. For each installation, standard choke and control valves were used as reference valves. In terms of downstream separation efficiency, the low-shear choke valves reduced oil-in-water concentrations respectively by 70, 45, and 60%, by total average. In the control valve application, the low-shear valve, which was located between the hydrocyclones and a compact flotation unit, reduced the oil-in-water concentration by 23%. In sum, the field installations have demonstrated that low-shear valves significantly and consistently reduce oil-in-water concentrations and thus improve the produced water quality. The results signify that low-shear valves may be used in debottlenecking separation and produced water treatment processes, reducing the environmental influence from produced water discharges. Because the low-shear technology enables processing of petroleum phases with less effort, energy, and chemicals, it also reduces emissions to air.

FEATURES OF APPLICATION OF SMALL RECONNAISSANCE ROBOT

2019 ◽  
pp. 29-38 ◽  
Author(s):  
R. Zinko ◽  
P. Kazan ◽  
D. Khaustov ◽  
O. Bilyk
Keyword(s):  
Mathematical Model ◽  
Armed Forces ◽  
Climatic Conditions ◽  
Design Stage ◽  
Experimental Sample ◽  
Single Trial ◽  
Test Cycle ◽  
Military Equipment ◽  
The Mathematical Model ◽  
Human Losses

A small intelligence robot (SSR) is a special military intelligence means. It is used to obtain information about the enemy - the collection of intelligence, the search for targets and target indication, observation of the situation, etc. The use of a small intelligence robot is assumed in various natural and climatic conditions: in temperate terrain, on soils with low bearing capacity, at low temperatures, in the desert, on sandy and marshy soils, on rocky soils, in elevated temperature and dustiness of air, and also in conditions highlands In the article an overview of modern developments of remotely controlled robotic military complexes, principles of their construction and perspective directions of development in the armed forces are reviewed. The issues of robotization of existing weapons and military equipment are considered. Every sample of a SSR used in combat action must possess all combat characteristics at once in an optimal ratio between them, ensuring its maximum effectiveness. Ignoring any of the properties or enhancing one property at the expense of others will not enable the full realization of the small surveillance robot. It is reasonable to select the relevant properties at the design stage, using the possibilities of mathematical modeling. The set of tactical and technical characteristics of the SSR allowed forming this. Its characteristics determine the scope and possibilities of application. The mathematical model of the SSR motion is written in the Matlab Simulink environment. Recorded mathematical model of SSR motion, formed single test cycle and input data allowed to conduct computer simulation of motion in possible conditions of operation of small surveillance robot.The single trial cycle presented contains a set of individual sites and reproduces the testing test cycle of a real polygon. On the basis of the developed tactical and technical characteristics of the SSR, the experimental sample was made. An example of the use of SSR for the intelligence of the settlement and at keeping the node of barriers has been provided. The efficiency of performing intelligence units’ tasks and reducing the risk of human losses are shown.

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