scholarly journals Rapid Testing and Interventions to Control Legionella Proliferation following a Legionnaires’ Disease Outbreak Associated with Cooling Towers

2021 ◽  
Vol 9 (3) ◽  
pp. 615
Author(s):  
Charlotte Young ◽  
Duncan Smith ◽  
Tim Wafer ◽  
Brian Crook
Keyword(s):  
Distribution System ◽  
Water Distribution ◽  
Cooling Tower ◽  
Quantitative Polymerase Chain Reaction ◽  
Cooling Water ◽  
Analytical Techniques ◽  
Remedial Action ◽  
Sampling Locations ◽  
Routine Monitoring ◽  
History Of

Most literature to date on the use of rapid Legionella tests have compared different sampling and analytical techniques, with few studies on real-world experiences using such methods. Rapid tests offer a significantly shorter feedback loop on the effectiveness of the controls. This study involved a complex of five factories, three of which had a history of Legionella contamination in their cooling water distribution system. Multiple sampling locations were utilised to take monthly water samples over 39 months to analyse for Legionella by both culture and quantitative polymerase chain reaction (qPCR). Routine monitoring gave no positive Legionella results by culture (n = 330); however, samples were frequently (68%) positive by qPCR for Legionella spp. (n = 1564). Legionella spp. qPCR assay was thus found to be a good indicator of cooling tower system health and suitable as a routine monitoring tool. An in-house qPCR limit of 5000 genomic units (GU)/L Legionella spp. was established to trigger investigation and remedial action. This approach facilitated swift remedial action to prevent Legionella proliferation to levels that may represent a public health risk. Cooling tower operators may have to set their own action levels for their own systems; however, in this study, 5000 GU/L was deemed appropriate and pragmatic.

scholarly journals Operating experience and ways to improve the performance of the service water supply system at the Novovoronezh NPP II (Units 1 and 2)

2020 ◽  
Vol 6 (4) ◽  
pp. 253-260
Author(s):  
Vladimir P. Povarov ◽  
Dmitry B. Statsura ◽  
Dmitry Ye. Usachev
Keyword(s):  
Distribution System ◽  
Water Distribution ◽  
Cooling Tower ◽  
Water Distribution System ◽  
Cooling System ◽  
Cooling Water ◽  
Operating Experience ◽  
Supply System ◽  
Summer Period ◽  
Service Water

The operating experience of Novovoronezh NPP II-1 shows that, in the summer period, the temperature of the cooling water exceeds the design value: this indicates the insufficient performance of the service water supply system. The main factor that has a negative impact on the performance of this system is the formation of carbonate deposits on the cooling tower filler. At Novovoronezh NPP II-1, the cooling tower water distribution system was cleaned from carbonate deposits by the method of combined vibration and aerohydraulic impact. The tested method of cleaning the filler cannot be considered optimal, since the main stage that determines the entire cleaning duration is the assembly/disassembly of the cooling tower filler. It is necessary to continue research on the choice of a strategy for controlling the carbonate deposition rate, taking into account the revealed influence of the design features of the main cooling water pipelines and pipelines of the cooling tower water distribution system on the mechanism of deposit formation in the peripheral spraying area. As compensating measures to ensure the required temperature regime of the turbine plant equipment at Novovoronezh NPP II-1, it is practiced during the summer period to put the standby heat exchangers of the lubrication system and the standby pump of the nonessential services cooling water system into parallel operation. This solution is fraught with the risk of an unplanned decrease in the electrical load if this equipment is turned off in the event of a malfunction. To increase the operating stability of Novovoronezh NPP II-1 and -2 in the summer period, it is proposed to carry out a number of measures aimed at mitigating the negative consequences caused by the elevated service water temperature. Equipment upgrade options are evaluated, e.g., by installing an additional pump for the turbine building services cooling system and (or) laying an additional pipeline to supply part of the makeup water from the Don River directly to the suction pipelines of the pumps of the turbine building services cooling system.

scholarly journals Developments towards 1MW Gyrotron Test Facility at ITER-India

2019 ◽  
Vol 203 ◽  
pp. 04013 ◽  
Author(s):  
Vipal Rathod ◽  
E. Sharan Dilip ◽  
Ronak Shah ◽  
Deepak Mandge ◽  
Amit Yadav ◽  
...  
Keyword(s):  
High Power ◽  
Distribution System ◽  
System Integration ◽  
System Performance ◽  
Water Distribution ◽  
Cooling Water ◽  
Current Drive ◽  
Integrated System ◽  
Test Facility ◽  
Industrial Grade

ITER-India, the Indian domestic agency for the ITER project, has the responsibility to supply a set of two high power Gyrotron sources (1 MW, 170 GHz, 3600 s) along with the auxiliary systems for Electron Cyclotron Heating & Current Drive applications. For such high power Gyrotron systems, one of the challenging areas is the system integration and establishment of reliable integrated system performance. ITER-India plans to establish the integrated Gyrotron system performance that essentially meets the ITER requirements in a Gyrotron Test Facility which is specifically being developed at ITER-India. This paper discusses about the recent updates towards the Test Facility development which includes, development of cost effective & modular Body Power Supply (BPS), Industrial grade prototype interlock & protection modules, a Gyrotron field simulator and cooling water distribution system.

Study of operation of natural draft cooling tower, with its hydraulic load reduced

2020 ◽  
Vol 12 (4) ◽  
pp. 268-273
Author(s):  
A. I. Badriev ◽  
V. N. Sharifullin ◽  
S. M. Vlasov ◽  
N. D. Chichirova
Keyword(s):  
Distribution System ◽  
Power Plants ◽  
Water Distribution ◽  
Cooling Tower ◽  
Air Flow ◽  
Thermal Power ◽  
Natural Draft ◽  
Irrigation Density ◽  
Hydraulic Load ◽  
Air Flows

A survey has been held of a BG-2600 natural draft cooling tower of thermal power plants, in the reduced hydraulic load mode. The technical condition of the reinforced concrete tower, the skeleton frame, the irrigation device, the water distribution system and the air duct windows has been inspected. Defects of the cooling tower structural elements have been identified. These include: horizontal sagging of the irrigation device, considerable gaps between its blocks and their partial destruction, problems with nozzles and structures of air duct windows. The identified defects are attributed to the causes of irregular water and air flows. The degree of irregularity of irrigation density and air flow in the tower has been estimated. Over the cross-section of the tower, a significant standard deviation from the average value or irregularity of irrigation density (30%) and irregularity of air flow (23.5%) has been established. The temperature and cooling curves of the cooling tower have been plotted taking into account irregularities of irrigation density and air flow rate. Normal and defective sections of the cooling tower have been identified based on working characteristics. Standard characteristics of the BG-2600 cooling tower have been plotted based on a nomogram. A comparative analysis of the working and standard characteristics has been held. The degree of influence produced by irregularities in water and air flows on the cooling process has been established. It has been found that the established irregularities in water and air flows result in a decrease in the temperature difference on average by 2°C and a decrease of cooling capacity by 7.3 Mcal/m2∙hr with a hydraulic load of 8840 m3/h. The results indicate a significant impact produced by irregularities of flows on cooling effect. The tasks to eliminate irregularities in distribution of flows as well as to increase the tower cooling efficiency have been formulated.

scholarly journals An outbreak of cryptosporidiosis in South London: what value the p value ?

1995 ◽  
Vol 115 (2) ◽  
pp. 279-287 ◽  
Author(s):  
H. C. Maguire ◽  
E. Holmes ◽  
J. Hollyer ◽  
J. E. M. Strangeways ◽  
P. Foster ◽  
...  
Keyword(s):  
Distribution System ◽  
Water Distribution ◽  
Tap Water ◽  
Current Treatment ◽  
P Value ◽  
Treatment Standards ◽  
Routine Monitoring ◽  
Sporadic Cases ◽  
Dose Response Effect ◽  
Geographical Association

SummaryAn outbreak of cryptosporidiosis which affected 44 people in January and February 1991 was identified through local surveillance at a South London Public Health Laboratory. Preliminary enquiries revealed that more than half the patients were adult and that there were no common factors other than geographical association. A case-control study showed a significant association between illness and consumption of tap water supplied by a particular water company, as well as a dose response effect. There were no apparent breaches or irregularities in the water distribution system and no indication of a problem through routine monitoring indices. This incident demonstrates the problems of establishing the source of cryptosporidiosis outbreaks in the absence of evidence of environmental abnormality, as well as possibly indicating that water conforming to current treatment standards may occasionally contain sufficient numbers of Cryptosporidium oocysts to cause sporadic cases or clusters.

Investigation of film formation in water-distribution systems by field emission sem and spectroscopy techniques

1996 ◽  
Vol 54 ◽  
pp. 212-213
Author(s):  
J. Liu ◽  
R. M. Friedman ◽  
E. Cortez ◽  
F. Pacholec ◽  
S. M. Vesecky
Keyword(s):  
Field Emission ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Film Formation ◽  
Analytical Techniques ◽  
Successful Implementation ◽  
The Public ◽  
Copper Leaching ◽  
Nucleation And Growth Mechanisms

EPA has set limits on the concentration of heavy metals in drinking water supplies to protect the public health. Furthermore, the failure of pipes in the water distribution system from corrosion represents a massive investment in rebuilding its infrastructure. We have initiated a program to study the formation of corrosion-inhibition films formed in potable water delivery systems using various chemical phosphate treatments. In particular, blends of ortho- and polyphosphates have recently been used to reduce both lead and copper leaching. Several factors are important to the successful implementation of the phosphate technologies, including film thickness and porosity, rate and stability of formation and water quality conditions. In an attempt to understand the performance of these phosphate blends, advanced analytical techniques have been employed to study the nucleation and growth mechanisms of the passivation films in a variety of water systems. We report here some preliminary results on the study of the film formation by field emission scanning electron microscopy (FESEM) technique.

The Invisible Landscape

2016 ◽  
pp. 411-421 ◽  
Author(s):  
Lorenzo Caponetti
Keyword(s):  
Sustainable Agriculture ◽  
Distribution System ◽  
Water Distribution ◽  
Water Distribution System ◽  
Water Systems ◽  
Engineering Method ◽  
Water Tunnel ◽  
History Of ◽  
Zero Emission ◽  
The Invisible

This chapter highlights the experiences and results of a decade-long investigation of an Etruscan water tunnel (cuniculum) on a central Italian farm and the adaptation of this engineering method to a contemporary water distribution system. The history of these drainage and water distribution tunnels is discussed and the attributes that have made it possible for Etruscan water systems to survive over two millennia are identified. The chapter then proposes ways that this technology can be applied to the challenges posed by sustainable agriculture today. The discussion concludes by comparing a zero emission water distribution system that is currently employed on the author’s farm to its Etruscan ancestor, and suggests how archaeological knowledge can be applied in contemporary agricultural contexts

A Method to Determine the Performance Characteristics of Cooling Tower Spray Zones

2010 ◽  
Author(s):  
Hanno C. R. Reuter ◽  
Dawie J. Viljoen ◽  
Detlev G. Kro¨ger
Keyword(s):  
Water Flow ◽  
Water Distribution ◽  
Cooling Tower ◽  
Cooling Water ◽  
Flow Distribution ◽  
Pressure Head ◽  
Distribution Data ◽  
Nozzle Height ◽  
Tower Spray ◽  
Nozzle Spacing

Cooling tower spray zones play an important role in cooling tower performance. Ideally they must distribute the cooling water uniformly onto the fill and must produce small drops at minimal pressure head to maximise heat and mass transfer in the spray zone with minimal pumping power. Limited thermal performance characteristic data is found in literature for cooling tower spray zones, since it is virtually impossible to measure spray zone performance accurately. In this paper, the method used to model the performance of cooling tower spray zones and results obtained for a medium pressure swirl nozzle are presented. Water flow distribution and drop size distribution tests are conducted on cooling tower spray nozzles to investigate the effects of varying different operating parameters, such as air and water flow rates, and installation parameters, such as nozzle height, nozzle spacing and direction of spray, on performance. The suitability of superimposing single nozzle flow distribution data to obtain the water distribution for a grid of equally spaced nozzles with variable nozzle spacing is investigated. Furthermore, a single nozzle simulation model is developed and used to model single spray nozzles. The single nozzle model and the superposition model are subsequently used to obtain initial drop conditions to model the spray zone using the commercial CFD package FLUENT®. The proposed modelling approach allows for the evaluation and performance prediction of existing and new nozzle design configurations. Correlations are presented for the Merkel number and loss coefficient for the downspray nozzle investigated.

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