Alfa Laval Niagara Wet Surface Air Coolers (WSAC®) are custom built, closed-loop cooling and condensing systems that combine high performance, low operating costs, compact size and reliable operation. Renowned for their robust design and high efficiency, Alfa Laval Niagara WSACs are used in a large number of demanding industries. Their low water consumption and high cooling capacity have made them a popular choice in applications where low temperatures are required for process improvements.
- Lowest possible process fluid outlet temperature thanks to evaporative cooling
- Minimal water consumption – cooling water can be re-circulated and the makeup water can be of low quality
- Low energy consumption
- Compact size and low CAPEX
- Well-proven technology and long service life
Alfa Laval Niagara WSAC systems are engineered-to-order, closed-loop cooling and condensing systems. Thanks to Alfa Laval’s WetSurface technology, these units provide maximum cooling in a compact unit and use a minimum of water and electric power. The robust and simple design brings stable thermal performance and low maintenance requirements. An Alfa Laval Niagara WSAC is a closed loop system, meaning there is no risk of contaminants entering the process stream. Our WSAC systems can be fully customized to your requirements, for example they can be designed to withstand corrosive media, cool several process streams in parallel or with the ability to run in both dry-cooling and wet-cooling mode.
Increase reliability and profitability with Alfa Laval air-cooled heat exchangers. Check out our brochure to find out how we can help you improve the sustainability of your plant.
Highly durable equipment
Alfa Laval Niagara WSACs are engineered to meet heavy-duty industrial requirements and standards. They can sustain pressures up to 2500 psi and be designed to meet ASME, TEMA, PED and API specifications. All materials in contact with the process stream can have full ASME material certification if required. The units are fireproof and can be constructed for use in Ex environments.
The tubes can be either straight or serpentine shaped. Straight tubes are the preferred choice for fouling process media and when a low pressure drop is required. The piping can be arranged and valved so that any tube bundle can be taken out of service for maintenance while the unit is in operation.
As standard, all components are made of hot-dip galvanized steel with excellent resistance to corrosion. For applications with corrosive media, the tube bundles can be delivered in a variety of materials, for example different grades of stainless steel, super duplex and titanium.
All Alfa Laval Niagara WSAC systems are unique and custom designed to fit the exact requirements of their intended duties. This includes inlet and outlet temperatures, ambient conditions, flow rate, presence of corrosive media, required pressure drop, etc.
Redundancy can be built into the units in order to minimize or eliminate downtime for maintenance. This can include components such as spare fans, spray pumps and even tube bundles. The units can also be designed to cool several separate process streams independently.
From small to large
WSAC systems come in all sizes from small, packaged units to large field-erected systems:
The packaged systems are skidded, pre-piped and pre-wired units, complete with control cabinets. These factory-tested, plug-and-play units ensure a fast and easy installation, and keep the associated installation costs low.
Our modular systems are ideal where cooling capacity needs to be expanded simply and efficiently. These medium sized WSACs have casings made of heavy-gauge steel and are delivered in pre-fabricated modules that are easily assembled on site.
Field-erected WSAC systems
Our largest systems are field erected. The basin is made of concrete and the overlying structure can be made of either fibre reinforced plastics (FRP) or concrete. A field-erected system is comprised of custom-designed tube bundles, which provide optimum maintainability over the lifetime of the system. A field-erected WSAC system offers the lowest total cost of ownership for duties where high-capacity cooling/condensing is required.
Comparison with other technologies
An Alfa Laval Niagara WSAC can replace:
- A cooling tower plus heat exchanger
- A traditional air-cooled heat exchanger (dry operation)
The following table outlines the benefits and drawbacks with the various technologies. In this example the air temperatures are:
Dry bulb T = 37.7°C (100°F)
Wet bulb T = 26.1°C (79°F)
|Wet Surface Air Cooler (WSAC)||Cooling tower plus heat exchanger||Traditional air-cooled heat exchanger (dry)|
|Practical approach temperature||5.6°C (10°F)||8.3°C (15°F) in total, 5.6°C (10°F) for CT and 2.7°C (5°F) for heat exchanger||8.3°C (15°F)|
|Coldest practical process temperature||31.7°C (89°F)||34.4°C (94°F)||46.1°C (115°F)|
|Water consumption||Low-medium||High||Not applicable|
|Total system cost||Low-medium||High||Medium-high|
How it works
An Alfa Laval Niagara WSAC uses evaporative cooling to reject heat from warm process media. The medium can either be a fluid or a gas and a WSAC can be used for liquid and gas cooling as well as condensing duties.
The warm process medium flows through tube bundles that are sprayed with water. The heat is released to the water on the surface of the tubes, causing the water to evaporate. A set of fans draws air over the tubes and removes the water vapour.
The water that does not evaporate is collected in a basin, passes a screen and is reused as spray water. A WSAC system can operate with a cycle of concentration of 6-10 without problems, i.e. the same cooling water can be reused 6-10 times, depending on water source and quality.
Shortly after the tube bundles, the air/water vapour stream is forced to make a 180° turn. This separates out the majority of the free droplets in the air, and they are collected in the basin.
The fans discharge the water vapour and air from the top of the unit. The air velocity is high to avoid recirculation.
Drift from an evaporative cooling system, such as a WSAC or a cooling tower, is when the exiting air stream contains water droplets. These drift droplets have the same chemical composition as the spray water. Thanks to its unique design, drift is minimal from a WSAC and drift eliminators are not usually necessary. The typical guaranteed drift rate without drift eliminators is 0.02%. With a drift eliminator the corresponding value is 0.0005%.
For liquid cooling the maximum inlet temperature is 82°C (180°F).
For single phase gas cooling the maximum inlet temperature is 232°C (450°F).
For vapour condensing the maximum inlet temperature is 82°C (180°F).
Reuse poor quality water
See how Alfa Laval Niagara WSAC cooling systems help increase cooling in a range of industries while reducing fresh water consumption through reuse of poor-quality water.
Boost cooling capacity
Discover how an Alfa Laval Niagara WSAC can improve cooling capacity and reduce fresh water consumption in an existing power plant by recycling blowdown from a cooling tower.
Learn how a US midstream gas company increased production by 25-30% by improving cooling capacity with an Alfa Laval Niagara WSAC. The payback time was less than a year.
Talk to an Alfa Laval expert
We will be happy to discuss the benefits a Wet Surface Air Cooler (WSAC) can bring you and show you how we can help improve your operation.
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