What material is used in drift eliminators?

Cooling Tower Drift Eliminators: Understanding Material Composition

For businesses utilizing cooling towers to manage excessive heat, the implementation of drift eliminators is essential. These devices are engineered to capture moisture droplets from the air flow and redirect them back into the cooling tower. You can find a variety of drift eliminators offered by suppliers in this market.

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Drift Eliminators Overview

A drift eliminator plays a crucial role in the operation of cooling towers. By effectively using these components, water is recycled, resulting in significant water conservation and preventing chemically treated water from escaping into the environment.

One of the primary functions of drift eliminators is to minimize water loss and lower emissions. Their main objective is to reduce both the drift rate and any pressure drop within the system.

Advantages of Implementing Drift Eliminators

The installation of drift eliminators in cooling towers brings considerable benefits not just to facility managers but also to the surrounding ecosystem:

• Prevents hazardous icing conditions on nearby roads and fields.

• Mitigates corrosion on piping systems and electrical equipment.

• Reduces the risk of short circuits caused by compromised electrical components.

• Substantially decreases the release of harmful chemicals into the air.

• Contributes significantly to water conservation efforts.

• Aids in lowering pressure drops during water circulation.

• Eliminates the necessity for additional water treatment procedures.

• Enhances the longevity of cooling towers.

• Optimizes energy consumption.

Core Components of Cooling Tower Drift Eliminators

Drift eliminators are straightforward yet critical components within cooling towers. Their simple structure comprises a few fundamental elements facilitating ease of installation and operation.

Seal

Seals are crucial in preventing drift bypass. These elements are typically added during the installation phase to ensure that no water droplets escape the system during their redirection.

Filter

Filters are essential for eliminating contaminants such as chemicals that could potentially pollute the environment.

Blades or Walls

Though the configurations of walls or blades may differ, they all serve a vital function in guiding the flow of water. Depending on the design, these components effectively drive water droplets back into the cooling tower for reuse.

Different Variants of Drift Eliminators

There exists a variety of drift eliminator designs, generally categorized into two primary types:

Counterflow Drift Eliminators - This type operates by allowing the air to flow through the fill vertically while water descends from the top, enabling a more efficient air exhaust process.

Benefits

• Reduced energy usage.

• Minimal maintenance requirements.

• Lower pump head necessity.

• Mitigation of plume emissions.

Crossflow Drift Eliminators - In contrast, this model utilizes horizontal airflow and descending water flow patterns, often employing a splash-fill method.

Benefits

• Low noise levels.

• Cost-effective solutions.

• Requires less maintenance.

• Delivers high performance.

• Optimizes energy utilization.

Key Designs of Drift Eliminators

Several design styles can either function in a crossflow or counterflow manner, indicating their orientation during installation.

Blade Design - Crafted from gauge blades secured with caps, this lightweight and durable option is designed to withstand use.

Cellular Design - Characterized by a wave-structured closure, these designs can redirect drift in multiple directions, employing centrifugal force to keep moisture away from the air stream.

Cassette Design - This robust yet lightweight variant facilitates easier lifting and is suitable for retrofitting, boasting a longer service life.

Fill-integrated Design - Utilizing integrated fillings like carbon black, this design enhances durability and adds an extra layer of protection against corrosion.

Common Construction Materials for Drift Eliminators

Manufacturers today primarily utilize a limited number of drift eliminator materials, ensuring quality without compromising on purpose:

Polypropylene (PP) - A sustainable material that offers excellent heat resistance compared to PVC. While it withstands moisture well, PP can deteriorate under prolonged UV exposure.

Polyvinyl Chloride (PVC) - Known for its widespread use and affordability, PVC is resilient to corrosion; however, it does produce toxic byproducts.

Metal - Steel drift eliminators are perfect for high-temperature environments and shipping applications but require protective coatings to resist corrosion.

Specifications for Cooling Tower Drift Eliminators

The market offers numerous models characterized by diverse options that may overwhelm newcomers. Typically, you should consider these common specifications:

• Type of installation (counterflow or crossflow).

• Design category (blade, cellular, cassette, etc.).

• Dimensions (depth, width, and length).

• Blade spacing and thickness.

• Maximum span specifications.

• Sheet sizing if applicable.

• Material gauge.

Desirable Features of Drift Eliminators

When narrowing down your selection, ensure the chosen model possesses most, if not all, of the following attributes:

• Compliant with safety regulations.

• Simple to operate, inspect, and maintain.

• Can achieve a drift loss of less than .001%.

• Exemplifies high performance.

• Cost-efficient options.

• Flexibility for modifications.

• Ensures smooth integration within processes.

Final Thoughts

Drift eliminators have established their utility over the years and should be upgraded periodically. We have provided insights into various drift eliminators, including models from Marley and Evapco. Consult with trusted cooling tower drift eliminator suppliers to enhance your confidence in implementation. Given the vast benefits drift eliminators offer to cooling tower operations, they undoubtedly represent invaluable solutions.

Material Influence on Drift Eliminator Efficacy

The key polymers commonly utilized in cooling tower fills and drift eliminators include polyvinyl chloride (PVC) and polypropylene (PP). Both materials are recognized for durability, adaptability to water-related environments, and economical production methods for creating a variety of designs suited for cooling tower applications. Nevertheless, both materials have a hydrophobic nature that affects their performance. The high surface energy of PVC and PP makes them repel water, leading to bead formation on their surfaces, which ultimately undermines the effectiveness of the fills and drift eliminators.

The inability of these polymers to promote effective wetting is directly related to their surface energy characteristics. For instance, PP possesses a significantly lower surface free energy compared to PVC, resulting in a lower affinity for water and increased bead formation. This is similar to the behavior of Teflon (PTFE), which has an extremely low surface free energy and causes water to bead up and slide off. This material characteristic is contrary to the intended design of fills and drift eliminators, where complete wetting is essential.

Fill Performance Analysis

Historical tests conducted by Brentwood on fill materials demonstrate that conditioning (or aging) benefits the efficacy of fill packs. Both PVC and PP packs were tested at varying conditioning durations and water loads, revealing that performance directly correlates with the period committed to conditioning until full saturation occurs. PVC packs reached complete saturation in approximately half the time required for PP packs, suggesting that for some low water loading scenarios, PP might not achieve full saturation, averting optimal performance.

Performance Evaluation of Drift Eliminators

The efficiency of drift eliminators parallels that of fills regarding the significance of surface conditioning for optimal performance. The effectiveness of drift eliminators is contingent upon moisture droplets forming a uniform film across their surface to facilitate drainage back into the cooling tower. Any water beads stagnating on the surface risk being dislodged by the air stream and lost to the atmosphere.

Brentwood has documented numerous instances where newly installed PVC drift eliminators exhibited drift issues, which were resolved after an appropriate conditioning period of ordinary tower operation, usually exceeding 1,000 hours under full heat load.

As regulations regarding drift emissions become increasingly stringent, potential disturbances at the air and water interface that could cause a drift test failure become more likely. When analyzing the conditioning rates of these fills, it’s evident that water loading influences efficacy. After three weeks in an accelerated aging tank operating at a rate of 3.5 gpm/ft2 (8.6m3/hr·m2), fill materials only achieved slightly over 90% capacity. Extending this hypothetical condition month by month implies that it may never attain complete potential. This raises an important question: if fills that are deliberately sprayed with water struggle to achieve saturation, what is the outcome for drift eliminators that receive far less water? Failure to form a coherent film may hinder the entire efficiency of these drift eliminators, emphasizing the importance of construction materials in enhancing their functionality.