Print this page Cooling Water Treatment
A. Bhatia, B.E.
Course Outline
The three primary reasons that the cooling water treatment may be required are to control corrosion, scale formation, and the growth of biological formation. Any of these problems – or more usually a combination of them – can cause a loss of efficiency, shorten equipment life and push up operating costs. Imagine the large amounts of dollars lost when insufficient cooling suddenly curtails operations of process equipments.
This 4-hr course presents an overview of common chemical treatment program that may be required to maintain cooling water systems in good operating condition. Reasons and means are discussed for controlling scale, deposition, corrosion, and biological fouling. The discussion also covers the information on chemicals used for control, and methods available to permit operation within the limits.
This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.
At the conclusion of this course, the reader will:
- Understand the critical parameters such as conductivity, TDS, pH, alkalinity and saturation index applicable to cooling water treatment;
- Understand the factors responsible for scale and corrosion;
- Understand the types of scale and methods to minimize its formation;
- Understand relationship between the cycles of concentration and blowdown;
- Understand the physical methods of treating water such as softener, dealkalizer, ion-exchanger, filtration, and electronic de-scaling equipments;
- Understand the corrosion types and the control techniques to mitigate corrosion;
- Learn four types of corrosion inhibitors including, anodic, cathodic, mixed and adsorption types;
- Understand the principles of cathodic protection;
- Learn the possible types of biological fouling and the treatment methods including oxidizing and non-oxidizing biocides;
- Understand the chemical feed equipment for closed and open cooling water systems;
- Learn the five application methods for dosing chemicals including their benefits and limitations; and
- Learn the control sensors and monitoring devices used in cooling water treatment.
Intended Audience
This course is applicable to all engineers, designers, energy auditors, O & M personnel involved in manufacturing, industrial processes, power plants, oil and gas, chemical and petrochemical process facilities, refineries, and HVAC systems in commercial buildings.
Benefit to Attendees
Attendees of this course will get practical knowledge of increasing the system performance of cooling water systems through the proper selection, implementation and operation of cooling water chemical treatment approaches encompassing corrosion, scaling and microbiological fouling. This course will provide insight into today's technology, which will help attendees to manage and prevent water, related cooling water system failures.
Course Introduction
Water is used in cooling systems as a heat transfer medium and frequently also as the final point to reject heat into the atmosphere by evaporating inside cooling towers. Depending on the quality of available fresh water supply, waterside problems develop in cooling water systems from: corrosion, scaling and microbiological fouling.
Any of these problems – or more usually a combination of them – result in costly unscheduled downtime, expensive parts replacements, and acid cleaning operations which reduce the life of the cooling system. Cooling water treatment is a vital part of preventive maintenance programs as insurance against costly unscheduled breakdowns and downtime.
This course provides comprehensive information on the modern cooling water treatment approaches.
Course Content
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Course Summary
Three major categories of problems in cooling water system are scale, corrosion and microbiological fouling.
Scale is caused by precipitation of minerals in the water onto the surface of metal components. The likelihood of a buildup of scale is determined by the hardness of water, which is based on its composition of minerals, such as calcium and magnesium.
Scale can be controlled chemically using substances such as polyphosphates, phosphonates and various polymers.
Corrosion may be the most damaging water treatment problem to deal with particularly for closed cooling systems. Although it also takes longer to develop than scale, corrosion is impossible to fix without replacing parts or equipment, so prevention is key. Corrosion is controlled using a number of different chemicals, depending on the type of system, discharge regulations and desired pH. The most common chemical treatment for systems with steel pipes is sodium nitrite. Other chemicals are sodium molybdate and azoles.
Microbiological problems, such as bacterial and algal growth, are primarily a problem in open-loop systems using cooling towers. Control of these is possible with the use of biocides. There are two classes of biocides: oxidizing and non oxidizing. The common oxidizing biocides are chlorine or hypochlorite, ozone and bromine. There are also non oxidizing biocides that are used in closed systems. These chemicals starve, suffocate or eliminate bacteria’s ability to reproduce. This class of chemicals has a very short half-life at the pH at which most closed systems operate, making it important to monitor them closely.
Finding the right balance of water treatment options is critical to a safe and effective strategy, and efforts to cut costs may be an expensive mistake. There’s always pressure to control costs.
The problem comes when cost is the emphasis and effectiveness is not.
Quiz
Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.
DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.
