Avoidance of Slack Flow in Liquid Pipelines

2004 ◽  
Author(s):  
Te Ma ◽  
Oliver O. Youzwishen ◽  
Michael Hylton
Keyword(s):  
Detection System ◽  
Pressure Head ◽  
Pressure Control ◽  
Leak Detection ◽  
Operating Conditions ◽  
Pipeline System ◽  
Hydraulic Analysis ◽  
Valley Bottom ◽  
Effective Manner ◽  
Pump Stations

There are many existing liquid transmission pipelines that have significant changes in elevation along their route, making them susceptible to operating at “slack flow” conditions. Slack flow occurs in a pipeline when the pipeline pressure falls below the vapor pressure of that liquid (i.e. the pressure head decreases below the elevation at a certain point and causes the gauge pressure at that point to drop below zero atmosphere). Separation of the fluid column occurs, which can result in leak detection system inaccuracy and poor pressure/flow control during pigging operations. The designs of older pipelines typically did not address the slack flow issue. In order to eliminate the occurrence of slack flow, some method of pressure control is necessary, such as the installation of a pressure regulator station (PRS). In this paper a case study is used to demonstrate how a detailed hydraulic analysis was utilized in the design of an effective PRS, to eliminate slack flow. The subject pipeline system was approximately 800 km in length; with six pump stations and one terminal tank farm. One section of the pipeline contained an elevation difference of more than 1000 m (between mountain top and river valley bottom), creating slack flow operating conditions. A decision was made by the pipeline operator to prevent (potential) over pressurization at the lowest point on the pipeline. A secondary goal was to upgrade the leak detection system by eradicating the slack flow operation. Designing and installing a PRS and an over-pressure safety valve station achieved both of these goals. The PRS design, operation philosophy and safety philosophy development utilized information derived from a transient hydraulic simulation of the pipeline, using a hydraulic pipeline simulator (HPS). By using transient hydraulic analysis, an optimized solution to slack flow and over-pressuring on a liquids pipeline with large elevation differences, was achieved. By installing a PRS in an optimized location the pipeline operator has increased the reliability of leak detection and reduced the risks of over-pressuring, in a safe, cost effective manner.

Overpressure Protections in Liquid Pipeline Hydraulic Design

2016 ◽  
Author(s):  
Alan X. L. Zhou ◽  
David Yu ◽  
Victor Cabrejo
Keyword(s):  
New Technologies ◽  
Pressure Control ◽  
Petroleum Products ◽  
Integrated System ◽  
Operating Conditions ◽  
Design Stage ◽  
Pipeline System ◽  
Protection Measures ◽  
Pipeline Systems ◽  
Pipeline Design

Continuous economic development demands safe and efficient means of transporting large quantities of crude oil and other hydrocarbon products over vast extensions of land. Such transportation provides critical links between organizations and companies, permitting goods to flow between their facilities. Operation safety is paramount in transporting petroleum products in the pipeline industry. Safety can affect the performance and economics of pipeline system. Pipeline design codes also evolve as new technologies become available and management principles and practices improve. While effective operation safety requires well-trained operators, adequate operational procedures and compliance with regulatory requirements, the best way to ensure process safety is to implement safety systems during the design stage of pipeline system. Pressure controls and overpressure protection measures are important components of a modern pipeline system. This system is intended to provide reliable control and prevent catastrophic failure of the transport system due to overpressure conditions that can occur under abnormal operating conditions. This paper discusses common pressure surge events, options of overpressure protection strategies in pipeline design and ideas on transient hydraulic analyses for pipeline systems. Different overpressure protection techniques considered herein are based on pressure relief, pressure control systems, equipment operation characteristics, and integrated system wide approach outlining complete pressure control and overpressure protection architecture for pipeline systems. Although the analyses presented in this paper are applicable across a broad range of operating conditions and different pipeline system designs, it is not possible to cover all situations and different pipeline systems have their own unique solutions. As such, sound engineering judgment and engineering principles should always be applied in any engineering design.

Modeling of Ethylene in Pipeline Leak Detection System

2004 ◽  
Author(s):  
Jakob Bu¨chert
Keyword(s):  
Real Time ◽  
Detection System ◽  
Leak Detection ◽  
Practical Experience ◽  
Time Model ◽  
Pump Stations ◽  
Pipeline Model ◽  
Improve Determination

This paper describes experiences with an improved equation of state (EOS) for ethylene for an existing real time pipeline model. The main scope of the model is leak detection, batch, contaminant and pig tracking. Altogether the pipeline model includes transportation of batched liquid ethylene, ethane, propane, butane and natural gas liquids (NGL). The pipeline is approximately 1900 miles miles long and includes laterals, 33 pump stations, 9 injection/delivery stations and 5 propane terminals. Originally the model used a BWRS EOS for all the above products. At that time a number of false leak alarms were experienced related to pipeline sections containing ethylene. A case study was carried out, specifically for ethylene, to investigate the effect of replacing the BWRS EOS with a modified Helmholtz EOS. The study showed that replacing the EOS on average would improve determination of the ethylene densities by 1.6%–5.6% with an expected reduction in the alarm rate for ethylene cases by approximately 50%. As a result the modified Helmholtz EOS was implemented in the real time model. Results are presented to show the practical experience with the new EOS gained over the last years.

Improved Leak Detection by Method Diversity

1998 ◽  
Author(s):  
Ruprecht M. J. Pichler
Keyword(s):  
Transient Flow ◽  
Detection System ◽  
Type System ◽  
Leak Detection ◽  
Operating Conditions ◽  
Detection Methods ◽  
Special Focus ◽  
Oil Pipeline ◽  
Knowledge Based ◽  
Noise Factors

Leak detection systems for liquid pipelines are installed to minimize spillage in case of a leak. Therefore reliability, sensitivity and detection time under practical operating conditions are the most important parameters of a leak detection system. Noise factors to be considered among others are unknown fluid property data, friction factor, instrument errors, transient flow, slack-line operation and SCADA update time. The opening characteristics and the size of leaks differ considerably from case to case. Each software-based leak detection method available today has its particular strength. As long as just one or two of these methods are applied to a pipeline a compromise has to be found for the key parameters of the leak detection system. The paper proposed illustrates how a combination of several different software-based leak detection methods together with observer-type system identification and a knowledge-based evaluation can improve leak detection. Special focus is given to leak detection and automated leak locating under transient flow conditions. Practical results are shown for a crude oil pipeline and a product pipeline.

High Speed Data Communications and High Speed Leak Detection Models: Impact of Thermodynamic Properties for Heated Crude Oil in Large Diameter, Insulated Pipelines — Application Pacific Pipeline System

2000 ◽  
Author(s):  
Travis Mecham ◽  
Galen Stanley ◽  
Michael Pelletier ◽  
Jim C. P. Liou
Keyword(s):  
Physical Properties ◽  
Crude Oil ◽  
High Speed ◽  
Detection System ◽  
Large Diameter ◽  
Leak Detection ◽  
San Joaquin Valley ◽  
Pipeline System ◽  
Oil Pipeline ◽  
Detection Model

Recent advances in SCADA and leak detection system technologies lead to higher scan rates and faster model speeds. As these model speeds increase and the inherent mathematical uncertainties in implicit method solutions are reduced, errors and uncertainties in measurement of the physical properties of the fluids transported by pipeline come to dominate the confidence calculations for computer generated leak alerts in the control center. The ability to collect more data must be supported by the need for better model data in order to achieve optimal leak detection system performance. This is particularly true when the products transported are non-homogeneous and have strong viscosity-vs-temperature relationships. These are characteristics of crude oils in California’s San Joaquin Valley where significant heating is required to pump these oils in an efficient manner. Proper characterization and correct mathematical expression of these physical properties in leak models has become critical. This paper presents these new developments in the context of an implementation of this new technology for the Pacific Pipeline System (PPS). PPS is a recently constructed and commissioned 209 km (130-mile), 50.8 cm (20″) diameter, insulated, hot crude oil pipeline between the southern portion of California’s San Joaquin Valley and refineries in the Los Angeles basin. Operational temperatures in this line vary from ambient to 82.2°C (180°F) with pressures ranging from 345 kPa (50 psi) to 11,720 kPa (1700 psi). Due to the unique geometry of the line, facilities along the route include pumping stations, metering stations and numerous “throttle-type” pressure reduction facilities. On PPS, a high-speed leak detection model is supported by a fiber optic (OC-1) communication backbone with data rate capacities in excess of 50 Megabits Per Second (MPS). Total scan times for the distributed communication system have been reduced to 1/4 second — each facility reports data to the SCADA host four times each second. A corresponding 1/4 second leak detection model cycle leads to selection of Methods of Characteristics segments on the order of 260 meters (850 feet). This resolution, in conjunction with the advanced instrumentation package of PPS, makes detection of very small leaks realizable. This paper starts with an overview of the system and combines a mix of the theoretical requirements imposed by the mathematical solutions with a practical description of the laboratory procedures and propagated experimental errors. The paper reviews temperature-related errors and uncertainties and their influence on leak detection performance.

Pipeline Rupture Detection Using Real-Time Transient Modelling and Convolutional Neural Networks

2018 ◽  
Author(s):  
Joel Smith ◽  
Jaehee Chae ◽  
Shawn Learn ◽  
Ron Hugo ◽  
Simon Park
Keyword(s):  
Neural Networks ◽  
Real Time ◽  
Detection System ◽  
High Reliability ◽  
Leak Detection ◽  
Sudden Onset ◽  
False Alarms ◽  
Pipeline System ◽  
Transient Model ◽  
Social License

Demonstrating the ability to reliably detect pipeline ruptures is critical for pipeline operators as they seek to maintain the social license necessary to construct and upgrade their pipeline systems. Current leak detection systems range from very simple mass balances to highly complex models with real-time simulation and advanced statistical processing with the goal of detecting small leaks around 1% of the nominal flow rate. No matter how finely-tuned these systems are, however, they are invariably affected by noise and uncertainties in a pipeline system, resulting in false alarms that reduce system confidence. This study aims to develop a leak detection system that can detect leaks with high reliability by focusing on sudden-onset leaks of various sizes (ruptures), as opposed to slow leaks that develop over time. The expected outcome is that not only will pipeline operators avoid the costs associated with false-alarm shut downs, but more importantly, they will be able to respond faster and more confidently in the event of an actual rupture. To accomplish these goals, leaks of various sizes are simulated using a real-time transient model based on the method of characteristics. A novel leak detection model is presented that fuses together several different preprocessing techniques, including convolution neural networks. This leak detection system is expected to increase operator confidence in leak alarms, when they occur, and therefore decrease the amount of time between leak detection and pipeline shutdown.

Near Real-Time Automated Detection of Small Hazardous Liquid Pipeline Leaks Using Remote Optical Sensing and Machine Learning

2016 ◽  
Author(s):  
Maria S. Araujo ◽  
Shane P. Siebenaler ◽  
Edmond M. Dupont ◽  
Samantha G. Blaisdell ◽  
Daniel S. Davila
Keyword(s):  
Machine Learning ◽  
Crude Oil ◽  
Real Time ◽  
Optical Sensors ◽  
Environmental Conditions ◽  
Detection System ◽  
Leak Detection ◽  
False Alarms ◽  
Different Types ◽  
Pump Stations

The prevailing leak detection systems used today on hazardous liquid pipelines (computational pipeline monitoring) do not have the required sensitivities to detect small leaks smaller than 1% of the nominal flow rate. False alarms of any leak detection system are a major industry concern, as such events will eventually lead to alarms being ignored, rendering the leak detection system ineffective [1]. This paper discusses the recent work focused on the development of an innovative remote sensing technology that is capable of reliably and automatically detecting small hazardous liquid leaks in near real-time. The technology is suitable for airborne applications, including manned and unmanned aircraft, ground applications, as well as stationary applications, such as monitoring of pipeline pump stations. While the focus of the development was primarily for detecting liquid hydrocarbon leaks, the technology also shows promise for detecting gas leaks. The technology fuses inputs from various types of optical sensors and applies machine learning techniques to reliably detect “fingerprints” of small hazardous liquid leaks. The optical sensors used include long-wave infrared, short-wave infrared, hyperspectral, and visual cameras. The utilization of these different imaging approaches raises the possibility for detecting spilled product from a past event even if the leak is not actively progressing. In order to thoroughly characterize leaks, tests were performed by imaging a variety of different types of hazardous liquid constitutions (e.g. crude oil, refined products, crude oil mixed with a variety of common refined products, etc.) in several different environmental conditions (e.g., lighting, temperature, etc.) and on various surfaces (e.g., grass, pavement, gravel, etc.). Tests were also conducted to characterize non-leak events. Focus was given to highly reflective and highly absorbent materials/conditions that are typically found near pipelines. Techniques were developed to extract a variety of features across the several spectral bands to identify unique attributes of different types of hazardous liquid constitutions and environmental conditions as well as non-leak events. The characterization of non-leak events is crucial in significantly reducing false alarm rates. Classifiers were then trained to detect small leaks and reject non-leak events (false alarms), followed by system performance testing. The trial results of this work are discussed in this paper.

Formulation and Analysis of the Probability of Detection and False Detection for Subsea Leak Detection Systems

2014 ◽  
Author(s):  
Alireda Aljaroudi ◽  
Faisal Khan ◽  
Ayhan Akinturk ◽  
Mahmoud Haddara ◽  
Premkumar Thodi
Keyword(s):  
Oil And Gas ◽  
Detection System ◽  
Oil And Gas Industry ◽  
Leak Detection ◽  
Probability Of Detection ◽  
Operating Conditions ◽  
False Detection ◽  
Potential Threat ◽  
Probability Of False Alarm ◽  
Detection Systems

Insuring the integrity of subsea process component is one of the primary business objectives for oil and gas industry. One of the systems used to insure reliability of a pipeline, is the Leak Detection System (LDS). Different leak detection systems use different technologies for detecting and locating leaks that could result from pipelines. One technology in particular that is gaining wide acceptance by the industry is the optical leak detection systems. This technology has great potential for subsea pipelines applications. It is the most suited for underwater applications due to the ease of installation and reliable sensing capabilities. Having pipelines underwater in the deep sea present a greater challenge and a potential threat to the environment and operation. Thus, there is a need to have a reliable and effective system to provide the assurances that the monitored subsea pipeline is safe and functioning as per operating conditions. Two important performance parameters that are of concern to operators are the probability of detection and probability of false alarm. This article presents a probabilistic formulation of the probability of detection and probability of false detection for fiber optic LDS based systems.

scholarly journals Methods of mathematical modeling of fire extinguishing systems and their implementation in the ISIGR software package

2020 ◽  
Vol 219 ◽  
pp. 04002
Author(s):  
Egor Mikhailovsky
Keyword(s):  
Flow Distribution ◽  
Pressure Head ◽  
Fire Fighting ◽  
Pipeline System ◽  
Hydraulic Analysis ◽  
Online Application ◽  
User Training ◽  
Software Products ◽  
Fire Extinguishing ◽  
Expected Benefits

The basis of fire protection of production, retail, warehouse, and other facilities are automatic fire extinguishing installations, internal fire fighting mains, and water curtains, which are an integral part of the water supply system. When designing such systems one shall perform the hydraulic analysis, the results of which allow selecting the required equipment mix, estimating performance of systems under different modes, and so on. The hydraulic analysis is usually performed either manually/with partial automation or using algorithms that implement numerical simulation methods. The latter requires readily available programs that greatly simplify making up the system of equations by forming an analytical model from the nodes and connecting branches. The software products currently available on the domestic market are either fail to deliver the expected benefits or have high cost and require user training. We present the conceptual and mathematical statement of the flow distribution problem with non-fixed nodal flows for an arbitrary pipeline system, including fire-fighting one, and the corresponding modification of the nodal pressure method that factors in the dependence of the flow through the nozzles (sprinkler, drencher) on the pressure (head) upstream. This and other problems lend themselves to solving with the help of the “ISIGR” online application package.

Full Integration of SCADA, Field Control Systems and High Speed Hydraulic Models: Application Pacific Pipeline System

2000 ◽  
Author(s):  
Travis Mecham ◽  
Bruce Wilkerson ◽  
Bryan Templeton
Keyword(s):  
Control System ◽  
Environmental Impact ◽  
Control Systems ◽  
Fiber Optic ◽  
Detection System ◽  
Leak Detection ◽  
Pipeline System ◽  
Scada System ◽  
Fiber Optic Communication ◽  
Optic Communication

Recent advances in PLC, SCADA and leak detection system technologies lead to the development of a highly integrated control system. Interconnected with fiber optic communication speeds (OC-1), this level of integration moves away from the historic model of stand-alone field controllers connected over low speed communication links to a centralized control center which, in turn, exchanges data from the host system to stand-alone leak detection processors. A new system design approach utilized familiar pipeline control elements such as PLC controllers and MODBUS communication protocols in combination with elements more typically associated with an office environment such as Windows NT servers, PC compatible computers, and Ethernet TCP/IP communications networks. These open-architecture components were used to fully develop, debug and test the SCADA system prior to system startup. The pipeline simulator is used as the centerpiece for this process to perform thorough operational validation of the system long before initial linefill. Once the various components were fully tested they were exported to the physical system in an operational state. The result is nearly seamless control systems supported by high data rates, high model speeds, common databases, and multi-channel communications. The increased level of integration has had dramatic impacts in leak detection, system safety, engineering development, operator training, and overall reliability of the control systems. The following paper presents a narrative overview of these new developments in the context of an implementation on Pacific Pipeline System (PPS). PPS is a recently constructed and commissioned 209 km (130 mile), 50.8 cm (20″) diameter, hot crude oil pipeline between the southern portion of California’s San Joaquin Valley and refineries in the Los Angeles basin. Following the Interstate 5 corridor over the “Grapevine”, Tejon Pass, Angeles National Forest and through heavily populated areas, this pipeline traverses some of the most environmentally and safety sensitive regions in the United States. The joint federal and state Environmental Impact Report / Environmental Impact Statement (EIR/EIS) set high hurdles for leak detection and control system performance. The historic control architecture and technologies were not adequate. This paper provides an overview of the environmental and physical constraints of the Pacific Pipeline System alignment, hydraulics, pumping and metering equipment, and block valve locations. It also discusses their impact on the design, programming and commissioning of a SCADA system meeting the requirements of the EIR/EIS. The paper then describes in more detail the fiber-optic communication system, control system architecture, SCADA system, leak detection models, simulator models and implementation methods, along with the engineering decisions leading to a comprehensive solution for the SCADA and leak detection requirements.

Online Closed Loop Pipeline Control by Transient Computer Model

1996 ◽  
Author(s):  
Ruprecht M. J. Pichler
Keyword(s):  
New Technology ◽  
Maximum Flow ◽  
Operating Conditions ◽  
Pipeline System ◽  
Maximum Throughput ◽  
Worst Case ◽  
On Line ◽  
Pump Stations ◽  
Fail Safe ◽  
Case Condition

Pipelines transporting different grades of crude oil or products usually operate with fixed setpoints for pressure limit switches and relief valves. These setpoints are calculated for a worst case condition as maximum flow rate combined with a sequence of batches of high viscosity ratio, etc. Under standard operating conditions, this worst case condition never occurs, so the setpoints restrict operating flexibility. With a transient simulation model it is possible to calculate these setpoints for actual hydraulic conditions on-line. Special attention has been paid to fail-safe operation of this on-line model and setpoint calculation. Our approach avoids all the problems linked to software in fail-safe applications and may be used for other applications of on-line simulation too. This concept has been successfully applied to a pipeline system in Austria, the AWP-Pipeline. With the new technology, substantial savings in energy costs (1–2 pump stations out of 11) as well as increased maximum throughput are possible now.

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