Adjustable speed drives improve circulating water system

The decontamination of Legionella pneumophila and other heterotrophic microbes by heat flushing in four legionellae-positive hot water systems was studied. Before the decontamination procedure, the concentration of legionellae varied from 3.0 × 10−3 to 3.5 × 10−5 cfu/L and the hot water temperature from 43.6 to 51.5 °C. During the contamination the temperature was raised to 60–70 °C. All taps and showers were cleaned from sediments and flushed with hot water twice a day for several minutes. The decontamination lasted for 2–4 weeks. In a few weeks the heat-flushing method reduced the concentration of legionellae below the detection limit (50 cfu/L) in the hot circulating water system just before and after the heat exchanger. The high hot water temperature also decreased the viable counts of heterotrophic bacteria, fungi, and total microbial cells determined by the epifluorescent microscopy. However, the eradication of legionellae failed in a water system where the water temperature remained below 60 °C in some parts of the system. After the decontamination, the temperature of hot water was lowered to 55 °C. Thereafter, all the studied hot water systems were recolonized by legionellae within a few months, showing that the decontamination by heat flushing was temporary. Also, the contamination of other bacteria increased in a few months to the level before decontamination.Key words: legionellae, hot water system, decontamination, water temperature, heterotrophic bacteria.

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The Pressure Loss Alarm System of Circulating Water in Calcium Carbide Furnace

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.401-403.1144 ◽

2013 ◽

Vol 401-403 ◽

pp. 1144-1148

Author(s):

Fen Su Shi ◽

Yang Zhou ◽

Yong Wu

Keyword(s):

Real Time ◽

Pressure Loss ◽

Water System ◽

Calcium Carbide ◽

Alarm System ◽

Monitoring Methods ◽

Field Bus ◽

Circulating Water ◽

Automation And Control ◽

Circulating Water System

In order to improve the manual monitoring methods of the circulating water in calcium carbide furnace, this paper designs a pressure loss alarm system about circulating water of calcium carbide furnace. The system completes real-time automation and control of circulating water system by combining PLC technology, field bus communication technology and configuration technology, which uses PROFIBUS field bus to communicate between upper computer and lower computer. The practical application shows that this system can effectively achieve real-time monitoring of the circulating water, fault diagnosis and maintenance management.

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Laboratory Investigation of Water-Side Scale And Corrosion in the Presence Of High Process-Side Temperatures

CORROSION ◽

10.5006/0010-9312-16.10.131 ◽

1960 ◽

Vol 16 (10) ◽

pp. 523t-529t ◽

Cited By ~ 4

Author(s):

HERMAN KERST

Keyword(s):

Calcium Phosphate ◽

Water System ◽

Laboratory Method ◽

Circulating Water ◽

Corrosion Rates ◽

Combination Treatments ◽

Water Side ◽

Circulating Water System ◽

Skin Temperatures ◽

Scale Deposition

Abstract A laboratory method of testing water-side corrosion and scale deposition in the presence of high process side temperatures has been developed. Two types of specimens are used: (1) a hairpin of ¼ inch seamless steel tubing mounted on a pipe plug and inserted in the circulating water system, and (2) a miniature heat exchanger made of ½ inch seamless tubing and standard pipe parts. In studies on corrosion rates, and on calcium phosphate scale deposition under conditions of 130 F water temperature and 350–395 F hot-side temperatures, it was shown that corrosion rates may be increased up to 8 times over the rates on immersed coupons at 130 F. A possible method of calculating water-side skin temperatures is indicated. It was shown that the use of polyphosphate treatments, at residual levels high enough to give corrosion protection, leads to the deposition of calcium phosphate scale. The use of chromate in combination treatments reduces the amount of this scale deposited, and also appears to reduce the amount of carbonate scale. 4.6.1

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Temperature Management During Off-Pump Coronary Artery Bypass Graft Surgery: A Randomized Clinical Trial on the Efficacy of a Circulating Water System Versus a Forced-Air System

Journal of Cardiothoracic and Vascular Anesthesia ◽

10.1053/j.jvca.2005.04.014 ◽

2006 ◽

Vol 20 (6) ◽

pp. 788-792 ◽

Cited By ~ 15

Author(s):

Alberto Zangrillo ◽

Federico Pappalardo ◽

Giuseppe Talò ◽

Chiara Corno ◽

Giovanni Landoni ◽

...

Keyword(s):

Artery Bypass ◽

Bypass Graft ◽

Water System ◽

Temperature Management ◽

Off Pump ◽

Circulating Water ◽

System Versus ◽

Forced Air ◽

Pump Coronary Artery Bypass ◽

Circulating Water System

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Failure of Circulating Water Pumps Discharge Header Cross Connect Valve — Optimum Solutions

Volume 1: Fuels and Combustion, Material Handling, Emissions; Steam Generators; Heat Exchangers and Cooling Systems; Turbines, Generators and Auxiliaries; Plant Operations and Maintenance; Reliability, Availability and Maintainability (RAM); Plant Systems, Structures, Components and Materials Issues ◽

10.1115/power2014-32003 ◽

2014 ◽

Author(s):

Mohammed Alismail

Keyword(s):

Sea Water ◽

Water System ◽

Normal Operation ◽

Problem Analysis ◽

Circulating Water ◽

Root Cause ◽

Maintenance Work ◽

Circulating Water System ◽

Water Pumps ◽

Cross Connect

The circulating water system is a very important system in Ghazlan Steam Power Plant- 4276 MW, as it supplies the sea water to the tubes side of the Condensers during normal operation. A large butterfly cross-connect valve was installed at the circulating water pumps discharge header to isolate the pumps and the header for maintenance. A forced unit shutdown occurred due to valve’s shafts end leakage and collapse after maintenance work. This paper explains the wrong design location of the valve in the piping as the root cause of the problem. Analysis with ASME reference will be presented. This paper will also present potential solutions and actions taken as a lesson learned to avoid occurrence in other plants.

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