A traveling water screen for a cooling tower is a self-cleaning water filtration system designed to remove debris from the water, prevent interference with cooling tower operation, and protect pipes, pumps, and people. These screens are custom-designed for specific locations and applications, with heavy-duty materials such as stainless steel 304, 316, or 317, and aluminum or mild steel frames coated for specific locations.
Understanding the Traveling Water Screen System
The traveling water screen system includes the following key components:
- Variable Speed Motor: Allows for adjustable screen speed to accommodate varying debris loads.
- Trough or Conveyor: Collects and transports the debris removed from the water.
- Elevator: Lifts the debris from the water onto the conveyor.
- Solenoid: Controls the operation of the spray bar.
- Submersible Pump: Provides the water pressure for the spray bar.
- Filter: Removes fine particles from the spray water.
- Control Panel: Manages the system’s operation and monitoring.
- Differential Level Control: Monitors the water level difference across the screen to trigger the cleaning cycle.
- Adjustable Timer: Allows for customized cleaning cycle intervals.
- Hand/Off/Auto Controls: Provides manual and automatic operation options.
- Belt Openings: Ranging from 3/32″ to 3″, depending on the specific debris and application requirements.
Additionally, generator-powered traveling water screen solutions are available for remote locations without access to reliable power.
Debris Removal Mechanism
The traveling water screen system consists of an elevator with a conveyor belt that lifts debris from the water. A spray bar helps remove debris from the screen, and the debris is then collected and disposed of. The system is designed to handle a wide range of debris, including:
- Floating plant matter
- Storm detritus
- Algae
- Construction material
- Garbage
Customization and Adaptation
These screens are designed to address specific debris problems and can be adapted to local conditions. For example, traveling water screens for algae and aquatic plant removal can be designed to address the rapid growth of plants like Water Hyacinth, which can quickly clog waterways if not removed.
Compliance and Comparison
Traveling water screens are commonly specified as a 316(b) solution for cooling tower water intake systems, along with wedge wire passive water intake screens. Both technologies meet the EPA’s 316(b) compliance standards, protect aquatic life, and prevent waterborne debris from clogging downstream equipment. However, there are key differences between the two systems that may impact decision-making, such as:
- Footprint
- Self-cleaning capabilities
- Debris removal
- Maintenance requirements
- Screen life
- Impingement survival
Selecting the Right Cooling Tower Screen
When selecting a cooling tower screen, it is essential to consider the environment, conditions, size, and scope of the operation, as the performance of the cooling tower will be dependent on the water screen’s performance. Vari-Flow cooling tower screens are designed to handle these variables, keeping exchangers free of debris, eliminating the need for screens to be removed for cleaning, and offering a simple “back flush” system that only requires one operator to clean the screen in a matter of minutes.
The Vari-Flow cooling tower screen system features the following specifications:
- Screen Mesh Size: 3/32″ to 3″
- Screen Material: Stainless Steel 304, 316, or 317
- Frame Material: Aluminum or Mild Steel (Coated)
- Cleaning Mechanism: Spray Bar with Submersible Pump
- Debris Removal: Conveyor Belt and Trough
- Control System: Variable Speed Motor, Differential Level Control, Adjustable Timer, Hand/Off/Auto Controls
- Power Options: Electric or Generator-Powered
By carefully considering the specific requirements of the cooling tower and the local environment, facility managers can select the most appropriate traveling water screen solution to ensure efficient and reliable cooling tower operation.
References:
– International Water Screens – Traveling Water Screens for Cooling Towers
– Hendrick – Passive Water Intake Screens vs. Traveling Screens
– CTVS LLC – What Is a Traveling Water Screen? Three Things to Consider for Your Cooling Tower