Table of Contents
- Importance of Water Treatment for Closed Loops
- Overview of Closed Loop Systems
- Considerations for Closed Loop Systems
- Closed Loop Water System Treatment
- What Happens when Microbiological Growth Goes Unchecked
- Industries that use Closed Loop Technology
- Closed Loop Water Treatment for Industrial Emergency Systems
- Industrial Applications of Closed Loop Systems
- Benefits of a Closed Loop System
- Contact Us
The Importance of Water Treatment for Closed Loop Systems
The water in your cooling or heating system dramatically affects performance. If you regularly monitor and treat the water in the cooling mechanism, it will reduce problems from water deposits. Monitoring the water quality of your cooling or heating system may not be a task you have the experience or equipment to do yourself, though. Don’t worry. You can get expert service for the water in your closed loop cooling system. But before you request a quote, you should understand your system and why water treatment is vital to maintaining it.
Overview of Closed Loop Water Systems
Cooling or heating systems that use water can dissipate heat acquired by the liquid with one of two methods — closed loop or open loop. The critical difference between these is the amount of exposure the water has to the air.
While sometimes more economical to install, open systems can have numerous problems with contaminants getting into the water of the cooling tower. Depending on the temperature, water can also evaporate or freeze from the open cooling tower.
A closed circuit system keeps the water completely enclosed inside pipes, preserving water volume and quality. Due to the lower maintenance requirements of a closed system, this type may have a lower price over time than a higher maintenance open circuit system.
Considerations for Closed Loop Systems
Closed loop systems have a reduced chance of contamination, but they are not maintenance-free. Neglecting the maintenance of a closed system promotes the growth of sludge and deposits. The most common problem with these systems is black magnetic iron oxide mud deposits. Over time, magnetic iron oxide particles bind together and collect on narrowed parts of the system. The most common places for this sludge include:
- Narrowed pipes.
- Heat-transfer surfaces.
- Cooling or heating coils.
- Fan coils.
Other problems can arise as the pH level of the water drops. Lowered pH could indicate bacterial growth or a system leak, affecting both the water levels and chemistry. In addition to leaks, bacteria or mineral deposits can reduce the ability of the system to transfer heat by coating the surfaces of the parts. Regular care of your components through water testing and chemical maintenance prevents the corrosion of the system's interior components.
While open systems need monitoring of water levels and watching for particulate matter from the environment, closed circuit systems need control of the water’s chemistry. Treating the water to prevent corrosion and freezing is part of maintaining these systems.
Closed Loop Water System Treatment
Proper closed loop water treatment should begin before the new system starts up for the first time. Once the closed loop system begins operation, you will not see the results of corrosion until the system shows signs of failure. That's why most water treatment services aim to prevent corrosion, scale and other microbiological growth.
In theory, a closed loop system should never leak. However, microbiologically influenced corrosion (MIC) can quickly lead to closed loop leakage in untreated systems. Before adding water treatment, on-site personnel should flush the closed loop to prevent bacteria from colonizing on the iron surfaces. This complete cleaning and flushing process is a highly effective defense against MIC.
The use of water treatment chemicals in closed loop systems will help prevent corrosion in numerous ways. The proper chemical treatment can:
- Target dissolved solids within the system to create less aggressive water.
- Maintain the pH level in the water so that it's within the noncorrosive range.
- Adjust the pH level to assist with problems resulting from colloidal iron.
- Remove oxygen from the water to slow the spread of metal corrosion.
- Form protective films on metallic surfaces and passivate them.
From complete cleaning and flushing to minor preventative maintenance, all treatments administered by ISO-certified technicians can help to prolong the system's lifespan.
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What Happens When Microbiological Growth Goes Unchecked
Abundant growth of bacteria, algae and fungi on surfaces can lead to microbiological fouling in cooling water systems. These microbiological problems usually develop more quickly and are more extensive in open loop systems. However, closed recirculating systems have an equal potential to support microbial growth, corrosion and fouling deposits.
When left unchecked, microbiological growth can quickly form a biofilm on wetted surfaces. This formation of microbial biofilms allows both aerobic and anaerobic bacteria to flourish, adversely affecting equipment performance, accelerating wood deterioration and promoting metal corrosion.
The control of biological agents, like bacteria and algae, is vital to any effective cooling water treatment. Biocides make it possible to control such factors, with two classes of biocides available:
- Oxidizing biocides: Chlorine-based compounds, bromine and ozone are the primary oxidizing biocides that provide broad control of biological agents. The pH of the water may impact the effectiveness of most oxidizing biocides.
- Nonoxidizing biocides: This class of chemicals is used in closed systems to suffocate, starve or eliminate the reproduction of bacteria. Nonoxidizing biocides have an extremely short half-life at the standard operating pH of closed systems and require close monitoring.
It is crucial to control bacterial levels in closed water systems from the point of the first fill. Flushing and chemical pretreatment are necessary to keep bacteria, algae and fungi from proliferating on pipe surfaces.
Industries That Use Closed Loop Technology
Several sectors take advantage of more efficient closed circuit cooling systems. These industries need to invest in a system that will operate at its peak and require lower maintenance levels throughout the year. Manufacturers, hospitals, industrial facilities and many other businesses and industries embrace the long-term efficiency and savings from closed loop technology. Effective water treatment ensures that your closed loop technology remains fast and effective, especially for industries that cannot risk extensive damages or prolonged downtime.
Closed Loop Water Treatment for Industrial Emergency Systems
Industries often need backup plans in the event of power losses. Some facilities require generators to keep the lights on, whereas others need an emergency cooling system to continue process and component cooling if the primary mechanism fails. Closed loop water treatment is essential for many industrial emergency systems that rely on cooling water.
For instance, backup power generators used for commercial structures like hospitals or industries typically have closed loop systems. The engines in these generators don’t require regular use, but they will need a cooling system when in operation. The increased efficiency of a closed circuit system from proper water treatment ensures the generator has adequate cooling water and is always ready.
Nuclear facilities and other power plants use closed loop water cooling for safety and non-safety components. Thanks to multiple cooling paths, the parts of a plant remain at a safe operating temperature. In nuclear facilities, redundant cooling mechanisms are critical to the safety of the plant. If the plant experiences a loss of its primary cooling, the closed loop system allows for continued heat removal. Like backup generators in hospitals, closed loop systems for nuclear power plants must always be ready to engage fully in an emergency.
Industrial Applications of Closed Loop Systems
Closed loop systems have more uses than for emergencies. Many industries use these for process cooling. For instance, most food and beverage processing plants use open cooling towers for process chilling. However, some plants have chosen more energy- and water-efficient closed loop systems for chilling. These facilities may use adiabatic systems, which apply pressure changes to alter temperatures. Other similar closed loop systems are used near the beverage chillers for more efficient, more tightly controlled cooling for each separate process.
Aside from emergency use, closed circuit cooling systems also serve to cool down components at a power plant. Water systems help cool bearings, while other coolers chill lube, air compressors and oil. At a power plant, the moving parts can generate enormous amounts of heat. Using a cooling water treatment can reduce the heat wear on these components, and a closed loop system cools while requiring less maintenance.
Benefits of a Closed Loop System
Closed loop systems offer several advantages compared to open systems. While closed loop heating or cooling costs more initially, over time, that cost gets offset by the savings from better efficiency in all conditions. If you already have a closed loop system, you’ll feel you made a quality investment. Should you need to replace your system, consider how a closed system can save you money — provided that you monitor and adequately treat the system over the years you use it.
1. Increases Efficiency
Closed loop systems are more efficient than open systems. Since their design keeps the water enclosed inside the system, closed systems do not require additional water periodically to replace that lost from evaporation. Efficiency also increases in the winter when closed loop systems can operate dry, preventing freezing during the colder months.
Their reduced need for maintenance means that you will benefit from lower maintenance costs and longer system operation. Because closed loop systems don't need a separate heat exchanger, as open systems do, they also take up less space in your facility. While you should not cease all care for your system, closed circuit designs will require fewer checks throughout the year.
To further save energy, closed circuit cooling systems allow for pump speed changes. Lowering the pump speed can conserve energy when cooling needs decrease. The flexibility to adjust to cooling and energy needs makes closed loop systems more energy efficient. However, this is not the only way closed systems can adapt to changes.
2. Ability to Adapt to Optimum Performance
Closed circuit cooling systems improve performance and efficiency by up to 50% savings compared to open systems. The closed circuit has four ways to adapt to cooling needs and outside temperature changes:
- Dry operation: The system runs without cooling water, which protects the system from freezing and puts off the need for water testing and chemical treatment. This option works best in moderate weather by pairing exhaust fans with the heat exchanger. You don’t need cooling water for this option.
- Free operation: Free operation happens when you shut off the chiller. This option uses ambient temperatures to cool the process water rather than a chiller.
- Adiabatic cooling: Facilities that operate in hot conditions may need the pressure changes of adiabatic cooling. A pressurized system can help cool the water to even lower temperatures than traditional methods can achieve.
- Variable speeds: Closed systems use variable speeds to maximize energy efficiency without sacrificing cooling power. This feature allows for greater control over the cooling process. Compared to fans that only have on-off controls, variable fans cut energy use up to 25%.
Adaptability makes closed systems a better option for variable climates, but ultimately the upkeep of the system will determine its cost over time. Luckily, closed loop systems have a design that reduces the need for regular, rigorous cleaning and maintenance. Effective pretreatment defends against the majority of closed loop system concerns.
3. Minimizes Exposure to Contaminants
Closed loop systems do not have an opening to the air, but this does not mean the system has complete protection from foreign matter in the water. Reducing the contaminants and debris in the system extends the entire system's life by lengthening the amount of time before components need replacements.
Thanks to the closed design, the system can go weeks between chemical treatments with well-treated and monitored water. In a system without any leaks, as long as water monitoring and treatment occur regularly, this scheduling should suffice to minimize pollutants. If you neglect the system too long, it can develop leaks which make it harder to maintain.
To prevent corrosion in carbon steel components, the water must maintain a high or alkaline pH. To keep the correct chemical balance, water treatment professionals have several options at their disposal:
- Polymer treatments: Once exclusively used for open cooling towers, polymer treatments now help maintain closed systems. These treatments disperse components in the water that may contribute to corrosion or scale. With a tightly closed system, polymer treatments do not affect the environment.
- Sodium nitrite: Sodium nitrite has a counterintuitive function. This chemical purposefully corrodes the entire system evenly so that the even corrosion leaves no uneven spots for additional wear. The downside to using sodium nitrite in a closed system comes from bacteria in the system. Certain bacteria consume sodium nitrite, which increases their population. High levels of bacteria can create films that contribute to corrosion.
- Sodium molybdate: Sodium molybdate inhibits oxidation. Unfortunately, the price of this compound varies wildly due to political unrest in areas associated with molybdate.
These substances are not the only options for maintaining a closed loop system, but they are a sampling of the products maintenance professionals could use.
Contact Chardon Labs for Closed Loop Water Treatment
Don’t neglect your closed loop water system. It still needs water treatment, despite myths to the contrary. Regular treatment of the water and the system itself will ensure it continues to operate flawlessly for years. Without routine care, your water could cause corrosion or excessive mineral deposits on the parts of the closed loop system. These conditions can quickly deteriorate your system without you knowing until efficiency drops to detectable levels.
To prevent serious harm from untreated water, you need frequent treatment of the system and its contents. The closed loop system will need an expert to change the filters, conduct pH balance checks and perform maintenance checks. At Chardon Labs, we can help with these tasks and many others for your system. We have water treatment professionals who know the right way to balance the water chemistry in your system. We won’t sell you chemicals. We provide you with a clean system via our expert maintenance. For more information about our water treatment and system maintenance, contact us today. We want to help you get a clean system that will last.
Matt Welsh is the Vice President and Water Consultant at Chardon Labs. He helps consult a wide range of customers utilizing various methods of water treatment, from chemical to chemical-free approaches, large and small applications, and across a wide range of geographical influences. With 20 years of water treatment experience, including a wide range of troubleshooting and service in potable water and non-potable HVAC and industrial applications, he is an expert in water treatment chemistry for cooling towers, boilers, and closed-loop systems.