Temperature Survivability and Surge Analysis for Bhogat Marine Facility

2019 ◽  
Author(s):  
Manuj Shukla ◽  
Kalyan Grandhi
Keyword(s):  
Single Point ◽  
Mooring System ◽  
Valve Closure ◽  
Oil Displacement ◽  
Closure Time ◽  
Temperature Loss ◽  
Transient Simulations ◽  
Marine System ◽  
Pressure Surge ◽  
Wax Appearance Temperature

This paper explains the complexity in marine tanker loading of highly waxy RJ Crude via Single Point Mooring System at Bhogat Terminal. It mainly presents the key challenges in temperature sustenance of Rajasthan Crude in the marine pipelines during the tanker loading operation. It also presents how the pump logic and valve closure timings are configured to prevent high pressure surge in the system. Due to the waxy crude characteristics of Mangala Crude, it is required to always maintain the Crude temperature above its Wax Appearance Temperature of 65 Deg C. As the marine system partly consists of non-heated section like the under buoy and the floating hoses, it was required to simulate the temperature losses in the system and provide a pipeline flushing sequence at the end of the operation. Various flow and operational scenarios are modelled in OLGA and recommendations are implemented for the system. Similarly, Surge analysis was performed in PIPENET to determine acceptable valve closure timing for the tanker valves, breakaway couplings (BAC), SPM and PLEM valves to prevent overpressure in the marine system. Based on the transient simulations, temperature loss during RJ crude export (at 4,636m3/hr) from terminal to the tanker in 24 hours is negligible (less than 10 Deg C). This indicates that the insulations in the pipelines are adequately designed for preventing heat loss. Whereas, the temperature in the hoses falls below 42 Deg C within 12 hours of shutdown which may lead to wax formation and may block the hoses. Therefore, RJ crude is to be flushed out of the system using flushing oil before it can cool to below its wax appearance temperature of 65 Deg C. It is recommended to insulate the bare pipe-works such as the PLEM, SPM and tanker if possible to facilitate a reasonable response time for setting up flushing oil displacement. It is also recommended that the pipelines are heated to 50 Deg C prior in advance of commencing flushing oil displacement operations to terminal and in preparation for RJ crude export. Based on the hydraulic surge analysis, a closure time of 30 seconds is acceptable for PLEM valve closure. It is recommended to trip the export pumps at loading arm pressure High High of 7 bara. However, closure of both the breakaway couplings (BAC) cause pressure surges which exceed the MASP of the hoses for BAC closure times of 10 to 60 seconds.

On the Optimum Utilization of Water Hammer

1988 ◽  
Vol 202 (4) ◽  
pp. 249-256 ◽  
Author(s):  
P H Azoury ◽  
M Baasiri ◽  
H Najm
Keyword(s):  
Water Hammer ◽  
Valve Closure ◽  
Pipe Length ◽  
A Value ◽  
Closure Time ◽  
Highly Sensitive ◽  
Pressure Surge ◽  
Comparison Of The Results ◽  
Optimum Water ◽  
Valve Area

The computerized method of characteristics was used to analyse, for a single pipeline discharging into the atmosphere, the effects of valve-closure schedule and pipe length on optimum water-hammer strength. It was found that the criteria of optimum water-hammer utilization are a non-linear inherent valve schedule in which the bulk of the pressure surge occurs near the beginning or towards the end of valve closure, together with as small a value of dimensionless valve-closure time and as high a value of wide-open valve area as is consistent with cavitation-free operation. Also, a comparison of the results with hydraulic ram test data suggests that optimum drive pipe length may be based solely on optimum water-hammer strength, in the light of the relative effects of pipe friction and dimensionless valve-closure time. In general, optimum pipe length is not highly sensitive to inherent valve-closure schedule, water-hammer strength, pipe size or reservoir head.

Charts for water hammer in pipelines resulting from valve closure from full opening only

1985 ◽  
Vol 12 (2) ◽  
pp. 241-264 ◽  
Author(s):  
Bryan W. Karney ◽  
Eugen Ruus
Keyword(s):  
Good Accuracy ◽  
Pipe Wall ◽  
Pressure Head ◽  
Wall Friction ◽  
Maximum Pressure ◽  
Valve Closure ◽  
Closure Time ◽  
Basic Parameters ◽  
Valve Opening ◽  
Open Position

Maximum pressure head rises, which result from total closure of the valve from an initially fully open position, are calculated and plotted for the valve end and for the midpoint of a simple pipeline. Uniform, equal-percentage, optimum, and parabolic closure arrangements are analysed. Basic parameters such as pipeline constant, relative closure time, and pipe wall friction are considered with closures from full valve opening only. The results of this paper can be used to draw the maximum hydraulic grade line along the pipe with good accuracy for the closure arrangements considered. It is found that the equal-percentage closure arrangement yields consistently less pressure head rise than does the parabolic closure arrangement. Further, the optimum closure arrangement yields consistently less head rise than the equal-percentage one. Uniform closure produces pressure head rise that usually lies between those produced by the parabolic and the equal-percentage closure arrangements, except for the range of low pressure head rise combined with low or zero friction, where the rise due to uniform closure approaches that produced by optimum closure.

Abstract 1606: High Specificity of Prolonged Isovolumic Contraction Time for Reverse Remodeling Associated with Cardiac Resynchronization Therapy

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Chinami Miyazaki ◽  
Charles J Bruce ◽  
Margaret M Redfield ◽  
Raul E Espinosa ◽  
David L Hayes ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Cardiac Resynchronization Therapy ◽  
Roc Analysis ◽  
High Specificity ◽  
Cardiac Resynchronization ◽  
Reverse Remodeling ◽  
Contraction Time ◽  
Valve Closure ◽  
Resynchronization Therapy ◽  
Closure Time

Background: Isovolumic contraction time (ICT) and pre-ejection period (PEP) are altered by electrical conduction delay as well as impaired contractility. An abnormal PEP has been used to select patients for cardiac resynchronization therapy (CRT), however, the predictive value of PEP for reverse remodeling (RR) has not been reported. The purpose of this study is to determine the predictive value of ICT and PEP for the RR in a prospective, single center CRT registry. Methods: Prospective registry of all heart failure patients undergoing CRT with echo pre-implant and at 3 and 6 months after implant. PEP was measured from the ECG Q wave onset to the aortic valve opening from the left ventricular outflow tract pulsed-wave Doppler tracing. The timing interval from the QRS onset to mitral valve closure was measured (mitral valve closure time). ICT was calculated as PEP-mitral valve closure time. RR was defined as >15% reduction in end-systolic volume (ESV) measured by biplane Simpson’s method. Death due to cardiac cause and heart transplantation during the 6 month period were considered as a non-response in the receiver-operating characteristics (ROC)analysis. Results: Echocardiography data was available in 83 patients at 3 and 59 patients at 6 month after CRT. RR occurred in 42 patients (51%) at 3 months and in 32 (54%) patients at 6 months By ROC analysis, the area under the curve (AUC) for predicting RR was 0.74 for ICT (p<0.001) and 0.73 for PEP (p=0.001) (See table ). ICT>123 ms yielded a very high specificity of 90–93% to predict responders at 6 month after CRT either in entire population or after excluding the patients with atrial fibrillation. Conclusion: A prolonged ICT is highly specific for predicting reverse remodeling after CRT although it is found in a limited number of patients. A strategy employing a screening ICT measurement may identify patients highly likely to achieve reverse remodeling after CRT, but can not be used to exclude patients for CRT. ROC analysis

Comparisons of CFD and Traditional Solutions for Steam Hammer Events

2017 ◽  
Author(s):  
Alex Mayes ◽  
Kshitij P. Gawande ◽  
Dennis K. Williams
Keyword(s):  
Pressure Wave ◽  
Power Plants ◽  
Peak Load ◽  
Critical Length ◽  
Pressure Change ◽  
Piping System ◽  
Valve Closure ◽  
Pipe System ◽  
Closure Time ◽  
Pressure Changes

Sudden pressure changes in the piping system of power plants are inevitable, and thus potential serious damage to large components, piping system, and piping supports is possible. To protect valuable components from such events, abrupt valve closure is employed to restrict the flow and prevent significant incidents and the resulting plant downtime. Unfortunately, when a valve is suddenly closed to prevent damage caused by unexpected events, a pressure wave within the flow is created, which travels upstream and impacts at the pipeline elbows. These events, involving sudden changes in pressure, are known as steam hammer. This steam hammer pressure wave, traveling through the pipe system, is capable of producing significant transient loads and stresses, which can disrupt the piping supports. As such there is a need for further investigation. The pressure wave depends on the characteristics of the flow, valve closure time, the elbow-to-elbow pipe section lengths, and the piping system flexibility. The present study performs a CFD analysis of the fluid experiencing such a sudden pressure change. OpenFOAM is used for this analysis and considers all the flow parameters, valve closure time, and critical length of the straight pipe. The study intends to provide a means of calculating the transient steam hammer loads applied on the pipe elbows, which consequently allows appropriate pipe support selection based upon the resulting peak loads. This computational analysis is compared to analytical methods for peak load determination such as rigid column theory, the Joukowsky method, and the steam hammer method explained by Coccio (1967) and Goodling (1989).

Effect of valve closure time on the determination of respiratory resistance by flow interruption

1987 ◽  
Vol 25 (2) ◽  
pp. 136-140 ◽  
Author(s):  
J. H. T. Bates ◽  
I. W. Hunter ◽  
P. D. Sly ◽  
S. Okubo ◽  
S. Filiatrault ◽  
...  
Keyword(s):  
Valve Closure ◽  
Respiratory Resistance ◽  
Flow Interruption ◽  
Closure Time

An Investigation Into the Effect of Turret Mooring Location on the Vertical Motions of an FPSO Vessel

1999 ◽  
Vol 121 (2) ◽  
pp. 71-76 ◽  
Author(s):  
K. P. Thiagarajan ◽  
S. Finch
Keyword(s):  
Oil And Gas ◽  
Single Point ◽  
Mooring System ◽  
Interior Space ◽  
North West ◽  
Design Considerations ◽  
Oil And Gas Fields ◽  
Offshore Oil And Gas ◽  
Gas Fields ◽  
Offshore Oil

Turret-moored floating production storage and offloading (FPSO) vessels have found application in several offshore oil and gas fields in Australia’s North West Shelf (NWS). These vessels are either custom-built or converted tankers, with an internal or external turret. The position of an internal turret is decided based on a number of design considerations, primarily, available deck and interior space, and weathervaning capabilities. It is known that turret position can influence vertical motions and accelerations of a vessel, but this factor has not been given much importance, in comparison with the effects on the horizontal plane motions, primarily surge. This paper presents the results of a pilot study conducted at the Australian Maritime College, Tasmania, to study the vertical motions of a single-point moored FPSO model in waves, while systematically varying the mooring position across the length of the model. The displacement of the vessel was held constant at 50-percent-loaded condition. A single-point mooring system was designed and implemented on the model to simulate the prototype turret mooring system. Results show that the mooring location significantly affects the vertical motions and accelerations of the vessel. Astern turrets were found to produce higher heave and pitch than other locations tested. Although turrets positioned close to the longitudinal center of gravity produced the lowest overall motions, it is suggested that turret position forward of midships be preferred, as it provides a balance between lowering vertical motions and improving weathervaning characteristics.

The Application of FPSO in Oil and Gas Exploitation

2012 ◽  
Vol 256-259 ◽  
pp. 1952-1955
Author(s):  
Ting Guo ◽  
Hong De Qin
Keyword(s):  
Oil And Gas ◽  
Single Point ◽  
Mooring System ◽  
Hydrodynamic Analysis ◽  
Comprehensive Review ◽  
Floating Structures ◽  
The World

The far-flung ocean has abundant resource and the exploitation area of ocean oil and gas is developing from offshore to deepwater and ultra-deepwater following the increase demand for oil and gas resource. Therefore, one of the floating structures for deepwater exploitation is FPSO. The yaw of FPSO is more important problem to solve. This paper use Hydrostar to compute the RAOs, 1st-order and 2nd-order force of FPSO. A comprehensive review is introduced about the research on FPSO hydrodynamic in the world, including the coupling hydrodynamic analysis of deepwater FPSO with the mooring system. The results indicate that the FPSO’s 1st-order force and moment is a little large, however, the RAOs and 2nd-order force and moment are good. The FPSO with single point mooring system can control the displacement of FPSO effectively.

Comparison of descending phlebography with quantitative photoplethysmography, air plethysmography, and duplex quantitative valve closure time in assessing deep venous reflux

1992 ◽  
Vol 16 (6) ◽  
pp. 0913-0920 ◽  
Author(s):  
Thomas S. Riles ◽  
Harold J. Welch ◽  
Eleni C. Faliakou ◽  
Robert L. McLaughlin ◽  
Susan E. Umphrey ◽  
...  
Keyword(s):  
Valve Closure ◽  
Venous Reflux ◽  
Closure Time ◽  
Air Plethysmography
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