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Closed Circuit Cooling Tower

What is Closed Circuit Cooling Tower

 

 

Closed circuit cooling towers, also known as evaporative fluid coolers, keep the system clean and contaminant-free in a closed loop. During operation, heat is transferred from the warm fluid in the coil to the spray water, and then to the atmosphere as a portion of the water evaporates. In addition to chiller applications and industrial process cooling, closed circuit cooling towers are often used with heat pump systems, where closed loop cooling is required.

 

Benefits of Closed Circuit Cooling Tower

Stability

Circulating water adopts soften water which running in the closed water circulation pipes, which will not produce scale at high temperature, effectively preventing the equipment components from being damaged gradually due to overheating. The constant temperature and alarm system are set by parameters, to ensure the cooling process is stable and the cooling effect is obvious.

Saving water

Compared with the traditional open cooling tower, it realizes the completely closed internal circulation of the cooling water (purified water / soften water), eliminating the need for digging pool and facilitating the relocation. It is particularly useful in areas where lacking water resource.

 

Saving energy

Adopts frequency conversion technology, which allows the cooling system to adjust the air and water spray volume in response to changes in ambient temperature, control the starting and stopping of fans and water spray systems, and maximize the efficiency and energy savings of the cooling process.

Environmental protection

Through closed circulation, circulating cooling water is not polluted and can be used continuously. Due to the low evaporation of the sprayed water, the enclosed cooling tower greatly protects the atmospheric environment.

 

 

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Why Choose Us

 

 

Years of Experience
Wuxi Keju Machinery Manufacturing Co., Ltd. is a high-tech enterprise in Jiangsu Province and is professionally engaged in cooling system development, design, manufacturing, sales, and service. And has 10+ years of experience in the cooling system field.

 

Quality System Certification
The company has passed 1OS9001-2008 Quality Management System Certification and worked out Q/320211JDM01-2013 Enterprise Standards. The company was also rated excellent management enterprise of the heat treatment industry in China, third-level enterprise of work safety standardization (machinery) in Wuxi City, cleaner production enterprise in Wuxi City and advanced energy conservation and emission reduction enterprise, and so on.

 

Professional Technical Team
After more than 10 years of continuous development and growth, the company now has formed a technical personnel team with complete and very high professional level and a production team with strong implementation force.

 

Excellent Services
The company can complete tasks with high quality and high efficiency, provide users with the best possible services, and also provide on-site training services, enabling operators to master the knowledge and experience necessary for operation, maintenance, and repair.

 

Different Types of Closed Circuit Cooling Towers

Evaporative Closed-Circuit Coolers

This type of closed-circuit coolers eliminates the need for a heat exchanger between the process loop and the heat rejection equipment. Unlike a cooling tower, where process water is used as the energy transfer medium and is open to the atmosphere, the coil inside a closed-circuit cooler isolates the process fluid.

Eco/Hybrid Closed Circuit Coolers

Hybrid coolers combine dry and evaporative cooling to maximize energy efficiency while simultaneously reducing water consumption. These units provide heat rejection in dry mode until the load exceeds dry rejection capacity. At this switch-over point, the unit enters evaporative mode to increase cooling capacity. Operating in wet mode only when needed can dramatically reduce annual water consumption, sewer expense, and eliminate plume while in dry mode.

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逆流闭式冷却塔

Adiabatic Coolers

Coolers function similarly to dry cooling systems, but with the addition of pre-cooling pads. Water runs over porous media while air is drawn through the pads, lowering the dry bulb temperature of the incoming air. The influence of reduced dry bulb temperatures at the coil provides greater heat rejection. As a result, adiabatic systems are most effective in hot, dry environments, and use up to 80% less water than traditional evaporative units. Adiabatic units also deliver the required cooling capacity in a smaller footprint and/or lower fan motor horsepower than a completely dry cooler.

Dry Coolers

Dry coolers are best specified where water conservation and reduced maintenance are the key considerations. Since dry coolers do not utilize any water or evaporative cooling whatsoever, dry coolers eliminate water treatment, all plume and Legionella concerns. However, dry coolers will use more energy and require a larger footprint than evaporative or hybrid fluid coolers of the same capacity.

 

Principle of Operation

 

 

Closed circuit cooling towers operate in a manner similar to open cooling towers, except that the heat load to be rejected is transferred from the process fluid (the fluid being cooled) to the ambient air through a heat exchange coil. The coil serves to isolate the process fluid from the outside air, keeping it clean and contaminant-free in a closed loop. This creates two separate fluid circuits: (1) an external circuit, in which spray water circulates over the coil and mixes with the outside air, and (2) an internal circuit, in which the process fluid circulates inside the coil. During operation, heat is transferred from the internal circuit, through the coil to the spray water, and then to the atmosphere as a portion of the water evaporates.

 

Differences Between the Open and Closed Circuit Cooling Towers

 

While open-loop cooling towers reject heat in a smaller footprint than closed loop fluid coolers (due to the process fluid being cooled via direct latent heat transfer), closed-loop systems benefit from sustained thermal performance of the entire system. Higher whole-system efficiency over time is achieved because heat transfer surfaces experience less fouling. Closed-loop systems also typically require less pumping horsepower than open loop systems of similar capacity.

 

In addition, compared to open-loop cooling towers, closed circuit cooling towers provide more flexibility in terms of where heat rejection equipment is installed. Closed-loop systems also do not require hydraulic balancing or equalization. Because of this, fluid coolers can be installed at or below the level of the connected system piping. Conversely, installing a cooling tower below grade or below the pump could result in the tower flooding when the unit shuts down.

 

Last but not least, closed-loop equipment also provide an advantage for cooling systems operating in sub-freezing outdoor temperatures. Some types of closed loop equipment may still require freeze protection of some sort, but all open loop cooling towers must be equipped with basin heaters, a drain-back design or a recirculation system for idle periods in freezing conditions.

 

 

Overview of the Importance of Cooling Water Temperature Range in Closed Circuit Cooling Tower

Generally speaking, the cooling water temperature range of a closed circuit cooling tower should be between 15 and 40 degrees Celsius. The temperature within this range can meet most industrial cooling needs, while also taking into account the changes in ambient temperature in different regions. When designing equipment, engineers need to determine the appropriate cooling water temperature range based on the actual application scenario to ensure effective cooling effect even under harsh climatic conditions.

In addition to environmental factors, the cooling water temperature range is also related to the construction and working principle of the equipment. For example, closed circuit cooling towers usually use a closed circulation system, which can avoid water evaporation and the entry of external pollutants, thereby ensuring the stability of water quality. At the same time, by accurately controlling the water temperature, the normal operation of sensitive processes and the consistency of product quality can be ensured.

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Material of Closed Circuit Cooling Tower

 

 

Materials used in the development of closed circuit cooling towers vary as they need to suit a variety of needs. In general, carbon, stainless steel, copper and ceramics are used because of their conductive qualities and durability. Forced or induced draft techniques may be used to move air or fluids through closed circuit cooling towers to increase performance and process efficiency.

 

Application of Closed Circuit Cooling Tower
 
 

Data Centers

Due to their superior water quality control, closed circuit cooling towers are ideal for data centers where maintaining clean water is crucial to prevent equipment damage.

 
 
 

Chemical and Pharmaceutical Industries

These sectors require high purity in process water, and closed circuit cooling towers effectively prevent contamination.

 
 
 

HVAC Systems

In commercial and residential buildings, closed circuit cooling towers provide stable cooling effects.

 

 

Components of Closed Circuit Cooling Tower

 

 

Motor
In refinery and petrochemical cooling tower applications, explosion-proof fan motors are essential because of the risk of leaks from heat exchangers. Additionally, these motors need to be equipped with protective systems, including overload relays and earth fault relays, to ensure safety and reliability.

 

Nozzles
Cooling tower nozzles are typically crafted from various plastics, such as polypropylene, ABS, PVC, and glass-filled nylon. These nozzles are designed to evenly distribute hot water throughout the cooling tower's cell.

 

Distribution Valves
These valves control the flow of hot water to ensure it is distributed evenly within the cells. They are designed to withstand harsh, corrosive conditions.

 

Drive Shafts
They deliver power from the motor’s output shaft to the input shaft of the gear reduction unit.

 

Gear Box
They reduce the magnitude of the speed depending on the requirements of the cooling tower. The gear reducer, motor and driveshaft are permanently alighted by the torque tube.

 

Water Distribution Piping
It must either be buried underground or properly supported on the ground to avoid thrust loading on the cooling tower. This thrust loading is due to the pressure exerted by the water in the pipe and the weight of the pipe itself.

 

Fans
Cooling tower fans are crucial components in closed loop systems. Common materials used for these fans include fiberglass, hot-dipped galvanized steel, fiber-reinforced plastic (FRP), and aluminum. Fiber-reinforced plastic is often preferred due to its lightweight nature, which helps to reduce the energy consumption of the fan.

 

Factors to Consider When Selecting Closed Circuit Cooling Tower
 

Understand Your Cooling Requirements
The first step in selecting a closed circuit cooling tower is to thoroughly assess your cooling needs. Calculate the total heat load that the cooling tower must dissipate, typically measured in BTUs (British Thermal Units) or kW (kilowatts). Identify the specific processes requiring cooling, such as HVAC systems, industrial machinery, data centers, or manufacturing processes. Define the desired inlet and outlet water temperatures to ensure the cooling tower is sized appropriately.

 

Evaluate Construction Materials
The materials used in the construction of the cooling tower significantly impact its durability and performance. Opt for materials that resist corrosion, such as stainless steel, galvanized steel, or corrosion-resistant coatings. Ensure that the materials are robust enough to withstand the operating environment and potential chemical exposure.

 

Consider Energy Efficiency
Energy efficiency is a critical factor in reducing operational costs and environmental impact. Choose towers with high-efficiency fans that consume less power. These drives adjust the fan speed based on cooling demand, reducing energy consumption. Select towers with low drift rates to minimize water loss and improve efficiency.

 

Factor in Maintenance and Accessibility
Regular maintenance is essential for optimal cooling tower performance. Ensure the tower design allows easy access to critical components for inspection and maintenance. Check the maintenance frequency and ease of replacing parts such as fans, nozzles, and fill media.

 

Analyze the Total Cost of Ownership
While the initial purchase price is important, consider the total cost of ownership (TCO). Factor in the costs associated with installing the cooling tower. Assess the tower's energy consumption and water usage. Consider the costs of regular maintenance and potential repairs. Assess the expected lifespan of the cooling tower and its components.

 

Seek Expert Advice
Consulting with an expert or a trusted supplier can provide valuable insights into selecting the right closed circuit cooling tower. They can offer recommendations based on your specific needs and help you navigate the various options available in the market.

 

What Measures Are Taken to Prevent Closed Circuit Cooler Tower from Freezing?

 

 

When the closed circuit cooling tower operates during cold weather conditions, taking reasonable antifreeze measures is a relatively simple and cost effective way to prevent or reduce icing.

 

The simplest and most effective way of protecting the heat exchanger coil from freezing is to use an inhibited ethylene or proylene glycol antifreeze. If this is impossible, an auxiliary heat load shall be added on the coils and minimum flow rate must be maintained in the coil at the same time so that the water temperature will not drop below 10 °C when the cooler is shut down.

 

If an antifreeze solution is not used in the coils, the coil must be drained immediately whenever the pumps are shut down or fluid in the coils stops flowing. This can be achieved by having automatic drain valves and air vents in the piping to and from the cooler. Cares must be taken to ensure that the piping is adequately insulated and sized to allow the water to flow quickly from the coil. This protection method shall be used only in emergency situations. It is neither a practical nor recommended method of freeze protection. Coils shall not be drained for an extended period of time as the pipe inside may be corroded easily.

 

When the unit operates in cold weather conditions, some type of capacity control is generally required to keep water temperature from dropping below 10 °C. Operating dry with a remote sump is an excellent way of reducing the heat rejection capacity of the cooler at low temperatures. Other methods of capacity control include two-speed motors, variable frequency driving and fan on/off. These methods can be used individually or in combination with dry/remote sump operation.

 

 
FAQ
 
 

Q: How does a closed circuit cooling tower work?

A: A heat transfer takes place between the process fluid inside the coil and the ambient air. This prevents direct contact between the process water and the external environment. By keeping the process fluid isolated from the atmosphere, a closed loop prevents contamination from dirt, dust and other pollutants.

Q: What is the difference between a closed circuit and open-circuit cooling tower?

A: The primary difference is how the cooling process is handled. Open-circuit systems allow direct contact between process water and ambient air, while closed circuit systems use a heat exchange coil to separate the process water from the external environment. Closed circuit towers are important for industries that require the strictest purity, like hospitals, or require precise, constant temperatures with no water escape, like data centers.

Q: What are the benefits of a closed circuit cooling tower?

A: Closed circuit cooling towers offer superior control over process fluid and contaminants. Because the fluid to be processed moves through an enclosed system, very little water is lost compared to an open-circuit tower. This makes the closed circuit design excellent for areas where water is scarce or where water must be extensively treated to be of useful quality.

Q: Are closed circuit cooling towers suitable for all climates?

A: Closed circuit cooling towers are suitable for a wide range of climates. They can be particularly advantageous in areas with harsh water conditions or limited water availability. Because they are closed, they are less prone to freezing and evaporation. The closed loop design also reduces chemical treatment, increases cycles of concentration and can operate in a dry mode when cold ambient conditions allow.

Q: How is water quality maintained in a closed circuit cooling tower?

A: Because the system is closed, the water stays in its uncontaminated state for far longer. The clean process fluid provided by a closed circuit cooling tower also reduces maintenance and wear to all connected components, extending equipment life and saving on replacement costs and downtime.

Q: What maintenance is needed for closed circuit cooling towers?

A: Common maintenance of conventional tower practices includes regular inspections of the heat exchanger coil and recirculating fluid loop. Monitoring fluid quality and conducting periodic fluid analyses are also very important.

Q: How often should maintenance occur?

A: Some maintenance occurs more regularly than others, but a full-tower health check should be conducted at least on an annual basis to ensure optimal performance.

Q: How often should you change the fill in a closed circuit cooling tower?

A: Typically, heat transfer media (otherwise known as fill) will need to be replaced once or twice during the life of a closed circuit cooling tower. The longevity of fill, or heat transfer media, is predominantly a function of water and air quality, as well as proper operation.

Q: What is the life expectancy of a closed circuit cooling tower?

A: In general, closed circuit cooling towers' life expectancy ranges between 15 – 20 years with proper water treatment and proper maintenance. After years and years of relentless operation, cooling towers require more than regular service or components replacement to maintain their original performance.

Q: What is the ideal temperature for a closed circuit cooling tower?

A: The ideal temperature range for a closed circuit cooling tower is typically between 15°C and 40°C (59°F and 104°F), depending on the specific application and ambient conditions, with the goal of maintaining a consistent temperature within this range to meet most industrial cooling needs while considering varying outdoor temperatures.

Q: What happens if a closed circuit cooling tower is not properly maintained?

A: Without proper system maintenance, cooling towers will become damaged and less effective at heat exchange, leading to performance and efficiency losses. However, with consistent maintenance and proper water treatment, you can keep your operations running, costs low and cooling efficiencies high.

Q: What happens if a closed circuit cooling tower freezes?

A: Ice at the air inlet and on the fans can lead to major operational issues and extensive damage, whereas ice on the structure may be less of an immediate concern. Cooling tower fans are delicate and cannot operate optimally when obstructed.

As one of the most professional closed circuit cooling tower manufacturers and suppliers in China, we're featured by quality products and good price. Please rest assured to buy the best closed circuit cooling tower for sale here from our factory. Contact us for custom service.

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