Cooling Water Analysis

Another interesting application is the trace analysis of sequestering agents in cooling water. Typically, these products are mixtures of polycarboxyhc acids and polyphosphonic acids, which are added to cooling waters as corrosion inhibitors. 

When using these conditioning agents, calcium bicarbonate is stabilized at thermally stressed positions in the system, and scaling on metal surfaces is prevented. 

Polyphosphonic acids are separated on a special latexed anion exchanger and detected photometrically after complexation with iron(III) nitrate [109] (see Section 3.8.2). With this method qualitative analysis of inorganic and organic phos- 

Chromatographic conditions see Fig. 9-60 pre-concentrated volume 2 mL peaks (1) polyphosphonate, (2) chloride, and (3) sulfate. 

In subsequent reactions other SN compounds are formed. Via hydrolysis, those compounds can release sulfate, so a reliable sulfate determination can only be performed by ion chromatography. 

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Microstructural examinations revealed branched, transgranular cracks originating on the external surface (treated cooling water). Analysis of material covering the crack surfaces revealed the presence of chlorine. 

The presence of tubercles is usually obvious. Friable brown and orange nodular encrustations on mild steel and cast iron cooling water components are almost always tubercles (Figs. 3.12 through 3.14). The presence of a crust, shell, core, cavity, and corroded floor are definitive (Fig. 3.3). Careful analysis can provide considerable information concerning growth, chemical composition, and associated metal loss. 

Visual inspection techniques are stressed as the most important tools used to study failures. This text is not a substitute for rigorous failure analysis conducted by experts, but it will help the reader identify and eliminate many cooling water system problems. Still, on occasion, the experienced, skilled, failure analyst using sophisticated analytical techniques and specialized equipment may be required to solve complex or unusual problems. Common sense, appropriate experience, and systematic investigation are, however, often superior to the more elaborate, but less effective, techniques used by some. 

Function event trees include primarily the engineered safety features of the plant, but other systems provide necessary support functions. For example, electric power system failure amid reduce the effectiveness of the RCS heat-removal function after a transient or small UJ( A. Therefore, EP should be included among the systems that perform this safety function. Siipfiort systems such as component-cooling water and electric power do not perform safety functions directly. However, they significantly contribute to the unavailability of a system or group of systems that perform safety functions. It is necessary, therefore, to identify support systems for each frontline ssstcm and include them in the system analysis. 

Cooling range Approach Design wet bulb Design dry bulb Water analysis - circulating - make-up... 

For many cooling waters, including seawater and also drinking water, where corrosion rates are 70 to 100% of the limiting diffusion current, the use of dimensionless group analysis can then be applied. 

New systems or processes may also need to be qualified from an operational safety perspective. This is particularly relevant in the case of chemical synthesis involving exothermic reactions. Critical safety aspects are usually identified using hazard operability or HAZOP assessments and studies. For example, a HAZOP analysis of an exothermic reaction vessel would involve consideration of the consequence of failure of the motors for mixers or circulation pumps for cooling water. Thus, the qualification of such a system would involve checks and assessment to ensure that the system/process can be operated safely and that pressure relief valves or other emergency measures are adequate and functional. 

Situations are often encountered when cooling water networks need to increase the heat load of individual coolers, which requires investment in new cooling tower capacity. Such situations demand a more complete analysis of the whole cooling water system. 

The work carried out by Dimmock and Midgley [14-16] at the Central Electricity Board, UK is concerned with the analysis of cooling waters, saline and non-saline. Although the analysis of seawater is not specifically discussed, their work may be of some relevance. 

Table 4.6. Checklist Analysis of Cooling Water Chlorination System...

E cooling water coil F lower electric connection G vacuum/argon connection. This scheme shows the use of the furnace for thermal analysis experiments. L differential thermal analysis head H reference thermocouple joints I thermostatic water circulation J thermocouple wires ... 

Bean RM, Thomas BL, Neitzel DA. 1985. Analysis of sediment matter for halogenated products from chlorination of power plant cooling water. In Proceedings of the 5th Water Chlorination Conference. Chelsea, Ml Lewis Publishers, Inc., 1357-1370. 

From Heno H.M. and R.D. Port, 1993, The Nalco Guide to Cooling Water System Failure Analysis, McGraw-Hill, Inc.)... 

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