Preventing Condenser Tube Failures Through Effective Cleaning and Nondestructive Testing

2009 ◽  
Author(s):  
Eric H. Fayard ◽  
Gary Fischer
Keyword(s):  
Nondestructive Testing ◽  
Sulfur Hexafluoride ◽  
Control Program ◽  
Electric Power Research Institute ◽  
Condenser Tube ◽  
Tracer Gas ◽  
Reliable Operation ◽  
Current Testing ◽  
Circulating Water ◽  
Gas Leak

Generating companies lose hundreds of millions of dollars annually to problems related to condenser and heat exchanger fouling, corrosion and tube leaks. In fact, the Condenser Tube Failure Control Program of Electric Power Research Institute (EPRI, Matthews, J.) disclosed that condenser tube failures contributed to almost 25,000 outages nationwide during a recent four year period and continue to be one of the most pressing issues related to plant output and availability. To adequately prevent condenser tube failures, effective condenser tube cleaning and nondestructive testing must be performed. Effective tube cleaning should ideally remove all deposits, leaving only the cleanest metal surface. Once tubes are free of fouling deposits, multi-frequency eddy current testing should be used to establish the overall integrity of condenser tubes. Plugging is recommended for the tubes with poor integrity that put condenser reliability at risk. If tube failures do occur, advances in tracer gas leak detection, specifically those using sulfur hexafluoride and helium, can be used to quickly locate sources of circulating water tube leakage and return the unit to reliable operation. This paper will examine implications of condenser tube fouling and failure, and the available nondestructive technologies for their prevention and correction.

Photoacoustic Leak Testing

2000 ◽  
Author(s):  
Serdar H. Yönak ◽  
David R. Dowling
Keyword(s):  
Carbon Dioxide Laser ◽  
Control Process ◽  
Noise Levels ◽  
Tracer Gas ◽  
Acoustic Environment ◽  
Matched Field Processing ◽  
Gas Leak ◽  
Quality Control Process ◽  
Leak Testing ◽  
Detection And Localization

Abstract Leak testing is a critical manufacturing quality control process. Unintended leaks in pressurized or evacuated containers may be detrimental to consumers, manufacturers, and/or the environment. This paper describes a leak detection and localization technique based on photoacoustic sounds produced by scanning a carbon dioxide laser over leaks emitting a photoactive tracer gas, sulfur hexaflouride. Photoacoustic signals are recorded in a bandwidth from 3 up to 110 kHz by multiple microphones. From these recorded signals, the presence or absence of a leak may be deduced by comparison with background noise levels. When a leak is present, its location is determined from a simple model of the acoustic environment and matched field processing (MFP). Current results show that a gas leak of 1 cm3 per day can be detected and localized to within ±1 mm in a few seconds using four microphones placed 0.41 m from the leak location and an incoherent average of the MFP ambiguity surfaces at twelve signal frequencies.

A LEAK QUANTIFICATION METHOD USING SULFUR HEXAFLUORIDE AS TRACER GAS

2004 ◽  
Vol 86 (6) ◽  
pp. 613-618 ◽  
Author(s):  
V. Vishnu Karthik ◽  
Andrew R. McFarland
Keyword(s):  
Sulfur Hexafluoride ◽  
Tracer Gas ◽  
Quantification Method

scholarly journals Reasonable Layout of High Drainage Roadways for Jiaojiazhai Mine

2022 ◽  
Author(s):  
Dongjie Hu ◽  
Zongxiang Li
Keyword(s):  
Control Program ◽  
Simulation Software ◽  
Fluid Simulation ◽  
Gas Extraction ◽  
Tracer Gas ◽  
Element Analysis ◽  
Gas Concentration ◽  
Working Face ◽  
Deformation Law ◽  
Better Than

Abstract To ensure that the gas concentration at the top corner does not exceed the limit, a reasonable level of the high drainage roadway layout in Jiaojiazhai Mine should be determined. In this work, based on the actual conditions of the working face, an SF6 tracer gas was used to test the connectivity between the high drainage roadway and the working face. A discrete element analysis program was used to simulate the deformation law of the overlying strata in the goaf, and a corresponding caving control program for the surrounding rock was written based on the obtained parameters and “O” ring theory. A fluid simulation software was used to simulate and analyze five goaf models with different high drainage roadway layouts (10, 15, 20, 25, and 30 m). The gas drainage data for two layers (10 m and 20 m) of the high drainage roadway were measured. The results showed that the height of the caving zone in the goaf is approximately 20 m, and when the high drainage roadway is arranged along the roof (when the layout layer height is 10 m), the roadway will be directly connected to the working face, thus pumping fresh air to the working face. The gas extraction effect of the 20 m stratum was better than those of the other strata. The simulation results of the gas extraction were consistent with the measured data. The proposed scheme was practically applied, and its effect was found to be evident, thus solving the problem of high gas concentration at the top corner and increasing the mine output.

An Outbreak of Airborne Nosocomial Varicella

PEDIATRICS ◽  
1982 ◽  
Vol 70 (4) ◽  
pp. 550-556 ◽  
Author(s):  
Tracy L. Gustafson ◽  
Gail B. Lavely ◽  
Earl R. Brawner ◽  
Robert H. Hutcheson ◽  
Peter F. Wright ◽  
...  
Keyword(s):  
Hospital Stay ◽  
Negative Pressure ◽  
Sulfur Hexafluoride ◽  
Index Patient ◽  
Nosocomial Transmission ◽  
Positive Pressure ◽  
Tracer Gas ◽  
Common Mode ◽  
Immunocompromised Child ◽  
Mode Of Transmission

An outbreak of nosocomial varicella was traced to airborne spread from an immunocompromised child hospitalized from Nov 11-19, 1980. Seventy potentially susceptible children were hospitalized on the ward during that period. Although the index patient remained in strict room isolation throughout his hospital stay, eight of these patients contracted varicella. The afternoon of November 12 was the period of highest risk for acquiring varicella. Eight of 36 patients (22%) present that afternoon, compared to none of 34 patients not present that afternoon, acquired the infection. A patient's risk of contracting varicella was significantly related to how near he/she came to the index patient's room that afternoon. Airflow studies, using the tracer gas, sulfur hexafluoride (SF6), demonstrated that patient rooms on this ward were at positive pressure with respect to the corridor. Despite isolation procedures, SF6 released in the index patient's room achieved concentrations in the corridor as high as 10% of those inside the room. Airborne spread of varicella has rarely been reported, but it may be a common mode of transmission in hospitals. We suggest that patients hospitalized with varicella be placed in strict isolation in negative-pressure rooms to reduce the risk of nosocomial transmission.

A Novel Technique for Eliminating Probe Lift-Off in Eddy Current Nondestructive Testing

2013 ◽  
Vol 291-294 ◽  
pp. 2474-2478
Author(s):  
Bo Ye ◽  
Ming Li ◽  
Fang Zeng
Keyword(s):  
Nondestructive Testing ◽  
Eddy Current ◽  
Measurement Accuracy ◽  
Excitation Frequency ◽  
Eddy Current Testing ◽  
Basic Principles ◽  
Current Testing ◽  
Novel Technique ◽  
Simulation Results ◽  
Lift Off

The lift-off problem is a very important problem in eddy current testing, which will influence the measurement accuracy. This paper proposes a novel technique for eliminating the probe lift-off in eddy current nondestructive testing. Firstly, the basic principles and characteristics of eddy current testing were introduced. Secondly, this paper analyzed and studied the coil impedance responses caused by the variations of the probe lift-off. Based on simulation results, this paper presents that choosing proper probe excitation frequency can eliminate the disturbance of coil impedance caused by the lift-off, and obtains better results.

Research on Rolling Force Model Based on Distributed Cooperative Control System

2013 ◽  
Vol 299 ◽  
pp. 93-96
Author(s):  
Hong Jie Li ◽  
Qing Xue Huang ◽  
Chang Jiang Ju ◽  
Xiu Lian Gong ◽  
Jian Mei Wang
Keyword(s):  
Cooperative Control ◽  
Steel Plate ◽  
Rolling Force ◽  
Control Program ◽  
Control Architecture ◽  
Force Model ◽  
Reliable Operation ◽  
Automated Production ◽  
Layer Composite ◽  
Distributed Cooperative Control

Three-stand mills continues produced of multi-layer composite steel plate, multiple L2 servers together computing to complete the tasks, serviced to many models in whole automated production process. In this paper, multi-embedded systems distributed and cooperative control program takes instead of multi L2 server mode, one L2 data collection and record server was remained. An example of rolling force model is used to discuss the control architecture, Sims simplified formula. The experiment and numerical results show that the control architecture is capable of reliable operation, and the accuracy of the target is no less than 94%.

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