Closed circuit cooling tower

Types of closed circuit cooling towers

A closed circuit cooling tower is a device that uses the cooling effect of air and water to remove excess heat from a process. It is a specialized cooling tower that is part of an external cooling system. There are several types of closed cooling towers available for use.

• Counterflow closed cooling tower

• Counters airflow in this type of cooling tower. The drop is vertical, and the air travels upward. It is a series of plenums where the fluid moves downward through the spray distribution system. The forced air draft blows across the filler and then collects in the water basin below. The direction of the air and water movement makes the tower more compact and suitable for limited spaces. Also, it maximizes heat transfer.

• Crossflow Closed Circuit Cooling Towers

• This type of closed-circuit cooling tower allows the air to flow horizontally. The water descends vertically through the fill. The design makes it easier to access the coil for maintenance. Also, it provides Anthony Campana and a large heat transfer area. Manufacturers use it for large industrial processes.

• Open-Loop Closed Circuit Cooling Towers

• In closed loop-cooling towers, heat transfers to the external coolant. An open-loop tower uses a spray nozzle for the fluid to flow over the coil. Then, an external pump returns the fluid to the process. Some benefits of this type of cooling tower are efficient water use, easy installation, and low operating cost. However, users consider the pump's cost and energy.

• Closed-loop cooling tower

In a closed-loop cooling tower, water does not evaporate. Instead, it circulates through the heat exchangers and coils. Heat transfer from the coil to the air happens via fans pulling ambient air. A heat exchanger is an integral part of a closed-loop cooling tower. It allows heat exchange but prevents water from getting contaminated from the environment. Some features of a closed-loop cooled tower are reduced water usage and less chance of environmental contamination.

• Hybrid cooling towers

A hybrid cooling tower combines forced-draft airflow and natural convection to improve thermal performance. It reduces water evaporation by recirculating water. Some benefits of a hybrid cooling tower are energy efficiency, lower environmental impact, etc.

• Wet/ dry cooler

Wet/dry cooling towers have a dry heat exchanger and an optional air-to-water heat exchanger. Some cooling towers are open while others are closed. A major benefit of a wet/dry cooling tower is its versatility. Users can modify configurations depending on cooling performance and water conservation requirements.

Specification and maintenance of closed circuit cooling towers

The specification of a closed circuit cooling tower varies depending on the design and model. However, some features and specifications are generally available.

• Materials

  Many cooling towers use galvanized steel or stainless steel material. The materials have corrosion resistance and a long service life. Besides, most materials have been surface-treated to improve their heat transfer efficiency.

• Airflow

  The cooling towers have different designs for airflow, such as crossflow and counterflow. The airflow direction affects the heat exchange efficiency. Also, the towers’ design is suitable for different applications.

• Heat transfer surface

  The heat transfer surface includes tube bundles and coils. The surface area determines the heat exchange capacity between the circulating fluid and the air.

• Fan

  The fan type and power affects the airflow volume and pressure. The towers may use axial flow fans or centrifugal fans with different powers.

• Water treatment system

  It includes filtration, chemical dosing system, and sensors. The systems monitor and maintain the water quality to prevent scaling and corrosion.

Maintenance

Maintaining a closed circuit cooling tower is crucial for its efficiency and performance. Regular maintenance ensures proper functioning, prolongs the equipment's life, and prevents costly breakdowns.

Usually, there are some routine maintenance tips for closed circuit cooling towers:

• Regular inspection: Users should regularly inspect the tower for any signs of damage, leaks, or corrosion. They need to check the fans and pumps to ensure they operate properly. Besides, the users should also monitor the water temperature and levels to detect any abnormalities.
• Cleaning: A periodic cleaning schedule helps to remove dirt and debris from the tower. The cleaning can prevent clogging of the heat exchange surfaces and maintain efficient heat transfer. Users can also clean the water tanks, pipes, and valves of the circulating system.
• Lubrication: Lubricating the moving parts like fan bearings and motor shafts helps reduce friction and wear. Regular lubrication reduces noise and energy consumption.
• Water treatment: It is essential to maintain the closed cooling tower's water quality. Users should treat the water with biocides, scale inhibitors, and corrosion additives. Proper water treatment can prolong the life of the circulating system.

Scenarios of closed circuit cooling towers

A closed circuit cooling tower can be used in various industries such as chemical, power generation, petrochemical, metallurgy, construction, food and beverage, pharmaceutical, electronics, automotive, water treatment, HVAC, fire protection, central thermal energy storage system, solar thermal energy collection and insulation.

• Industrial Processes: Many industries such as chemical, petroleum, metallurgy, machine manufacturing, food processing, plastics, paint, papermaking, power plants and more use closed-circuit cooling towers to cool equipment, reactants, solvents, cutting fluids, hydraulic oils, extrusion materials, high-temperature gas, etc., ensuring stable production and product quality.
• Mechanical Equipment Cooling: Closed-circuit cooling towers can be used to cool various mechanical equipment such as CNC machine tools, lathes, milling machines, compressors, engines, pumps, reducers, and more. They help maintain optimal operating temperatures, prevent overheating, and ensure the smooth operation of equipment.
• Centralized Cooling Systems: A closed-cycle cooling tower can serve as the central cooling unit in a centralized cooling system. Multiple cooling loads can share a cooling tower, thereby improving system efficiency, saving energy, and reducing equipment investment and space usage.
• Energy Recovery Systems: Closed-circuit cooling towers can also be used in energy recovery systems, such as combined cooling, heating, and power systems. By recovering waste heat from industrial processes or other sources, closed-circuit cooling towers can help regenerate valuable cooling or thermal energy, thereby improving overall system energy utilization.

How to Choose a Closed Circuit Cooling Tower

When buying a closed circuit cooling tower, one should consider factors such as the system's application, space requirements, maintenance accessibility, and water quality. Also, the initial cost, energy efficiency, noise level, and environmental impact of the cooling tower are critical to its selection.

Different types of closed circuit cooling towers are designed for various applications. So, it is essential to match the tower with the equipment that requires cooling. Also, the circulating water volume affects the size of the cooling tower. It is crucial to select a tower that can accommodate the flow of water. In addition, the tower's footprint should fit within available space.

Indeed, a closed circuit cooling tower needs regular maintenance for optimal performance. Therefore, it is vital to choose a tower with accessible parts like the air finned tubes, pumps, and drift eliminators. These areas are commonly serviced. Moreover, the quality of water used in the process determines if the tower develops deposits or corrosion. It is crucial to select a tower that matches the user's water conditions.

The upfront cost of the cooling tower can be significant, so buyers want an option that offers energy-efficient performance. Pay attention to the tower's fan system, motor, and design, as they contribute to energy efficiency. The noise level of a closed circuit cooling tower is also a considerable concern. Opt for models with sound attenuators or quiet fans to minimize disruption in the environment. Also, investigate the environmental impact of the cooling tower, including carbon emissions and water usage. Choose a tower designed to promote sustainability.

FAQ

Q1: What types of industries use closed circuit cooling towers?

A1: There are many possible applications for a closed circuit cooling tower. Generally, any industry that uses large amounts of water for cooling and where the water must remain clean can use this equipment. This includes the oil and gas industry, chemical and petrochemical sectors, power generation plants, plastics and food manufacturing factories. Water from closed circuit cooling towers also often cools HVAC systems, compressors, gas turbines and refrigeration units.

Q2: How long can a closed circuit cooling tower last?

A2: The typical lifespan of a closed circuit cooling tower is 15 to 20 years with regular maintenance. However, some well-maintained towers can last for over 30 years.

Q3: Is a closed circuit cooling tower more expensive than an open one?

A3: Closed circuit cooling towers are generally more expensive than open circuit towers due to the closed loop and heat exchanger. However, the cost difference may be negligible if the repeat evaporative losses in an open cooling tower are considered. Because water in a closed circuit cooling tower does not evaporate at the same rate as in an open tower, users can save on water, treatment chemicals, and anti-fouling-filtering-sterilizing system.

Q4: How often should the closed circuit cooling tower be cleaned?

A4: At least once a year cleaning is the minimum requirement for most towers. In some cases, frequent cleaning may be required, like in areas with high levels of dust and other pollutants. Typically, hiring the tower's manufacturer or a specialized service provider is advisable. These professionals have the right skills, equipment, and chemicals to clean the tower effectively and safely.