Cooling water systems management

NOTE In this chapter there is discussion concerning some individual aspects of corrosion, fouling, and deposition, but every attempt is made to link them together into a coherent whole. It is also incumbent upon the reader and water treatment practitioner to consider each specific problem or aspect of water management in the light of the complete, dynamic, cooling water system. 

Over the years, the use and application of several different saturation indices that aid the prediction of scaling and corrosion potential in different waters have evolved to become an integral part of the business of treating and managing cooling water systems. The two most popular are the Lange-lier Saturation Index (LSI) and the Ryznar Stability Index (SI), which were both introduced more than 50 years ago. 

Special costs. Special costs include land, spare parts, inspection, project management, chemicals, miscellaneous supplies, and office and laboratory furniture. For preliminary estimates, these costs can be estimated as 4% of the cost of the process units, storage, steam systems, cooling water systems, and offsites. Engineering costs and contractor fees are included in the various individual cost items. 

The paper discusses a two-step approach to guide an ammonia plant operator in the design, selection, and implementation of the optimum cooling water management program for this cooling system. 

Operators of cooling systems located close to estuaries may find seasonal fluctuations that raise the chloride in their cooling water to 800 to 1200 ppm Cl. This level of chloride is probably about the maximum that can be tolerated in a cooling system under any normal circumstances, and good management is required if serious problems are to be avoided. 

Calculation of the pHf and LSI has become standard procedure as a tool for the management of cooling systems everywhere around the world. The LSI is typically calculated for actual sources of makeup water and actual recirculating cooling waters. It is also used in what if situations to compare predictions of recirculating water scaling or corrosion potentials, both at current cycles of concentration and at various proposed future cycles of concentration. 

NOTE In a poorly managed cooling system, the cooling water LSI (as calculated from pWaciuai) tnay be startlingly different from an LSI calculated from cycling up the makeup water (which is a different problem). 

There are often several areas for potential improvement, even in supposedly well-managed cooling water accounts, and it is not unknown for temporary problems to simply drift and eventually become permanent features of a cooling system. The problems just never seem to receive proper attention by either the customer or the service company s field representative, but they can be rapidly picked up by the competitors. 

Selecting a suitable cooling water program often requires the vendor to take into account an even wider variety of factors, and then to tailor the program so that it matches the needs of both the cooling system and the personnel associated with its operation and management. 

All cooling water treatments produce the best results in clean well-maintained cooling systems. (It is easier to keep a clean system clean than to prevent a dirty system from getting dirtier.) Therefore, it is in the field representative s best interests to ensure that a suitable program for maintenance management and good housekeeping practice is implemented. These activities should also be planned and documented, similar to all water treatment activities. 

Modem cooling water treatment practice is the planned, actioned, and documented management of cooling systems to produce and maintain operational and economic benefits for the users. 

We have used the reactor cooling water valve to stabilize the system by controlling reactor temperature. However there is no specific temperature at which the reactor must operate. The best way to manage the reactor temperature setpoint is not immediately obvious. It might be used in conjunction with the production rate controller, i.e., higher temperatures may be needed to increase throughputs. It might be adjusted to maximize yields and suppress undesired by-products. 

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