Serving as an alternative to traditional process-cooling methods, this technology improves operational costs and enhances equipment efficiencies. By leveraging intelligent process cooling (IPC), heat-treating operations can surpass the limitations of existing technologies to deliver quantifiably better results.
Traditional Process-Cooling Systems
For decades, heat-treating operations have relied on traditional systems to cool their furnaces. These technologies include open cooling towers, conventional dry coolers and centralized chiller systems. Each technology, though striving for the same goal, offers a different approach to process cooling. And each has its considerable limitations and disadvantages.
Frigel’s IPC systems are designed to overcome these limitations. This technology leverages a unique closed-loop dry-cooling system with an internationally patented adiabatic chamber to cool water and circulate it to and from primary processing equipment directly and/or to and from smaller chillers positioned near each heat-treating process or work cell, where colder water is required. It eliminates the need for an open cooling tower, dry cooler or central chiller system.
Here’s a look at traditional process technologies and their inherent limitations.
- Evaporative cooling towers: There are two generic types of these systems. In both cases, they are limited in supply temperature to process by the ambient wet-bulb temperature. Typically, they can provide only 85˚F water or higher to process year-round. Therefore, they cannot be used to produce water for heat-treating components that need colder water.
- The first and most common type is a conventional open system, which evaporates the process water, releasing latent heat and, thus, cooling the water. These systems consume excessive amounts of water and chemicals. It also requires bleed-off of the process water (and, therefore, additional chemicals) to maintain proper hardness levels of the process water. This type also requires intense filtration and chemical treatment methods.
- The second type involves heat exchangers either in the tower itself or free-standing to isolate the contaminated evaporative side of the system from the process loop. Although this type of system provides closed-loop water to process, it does not reduce the amount of water evaporated, nor the amount of chemicals and filtration required.
- Conventional dry coolers: This type of system uses ambient air to cool the process water through finned-tube heat exchangers. This type of system does not rely on evaporation. As such, it eliminates the excessive water consumption and reduces the chemical treatment requirements typical of cooling towers. However, this type of system can only produce water that is typically 10-15˚F above the ambient dry-bulb temperature. Therefore, in warmer climates, temperature tolerance can be lost. In addition, in cold climates, this type of system requires the use of glycol antifreeze solutions, which are expensive and cannot be used for certain heat-treating components without water-to-glycol heat exchangers and the associated additional pumping systems.
- Central chillers: These provide cooling water at one temperature to the heat-treating equipment and work cells, fulfilling cooling needs for multiple machines. This process uses a pumping system to direct cold water (typically 50-65˚F) to the machines, absorbing the heat and returning the heat-laden water to the chiller. The heat is transferred to the refrigerant from the process-cooling water. The heat must then be rejected. There are two types of heat-rejection configurations. In both cases, the cold water can be unnecessary for most heat-treating components and, therefore, is not energy efficient. The two configurations include:
- Air-cooled systems, which expel the heat directly to ambient, similar to a typical home air conditioner.
- Water-cooled systems, which employ a condenser (refrigerant-to-water heat exchanger). Heat is transferred from the refrigerant to the cooling tower water loop. This heat is then expelled to ambient by evaporation as described with evaporative cooling towers.
In comparing Frigel’s solution to traditional technologies, heat-treating operations are strongly positioned and have more flexibility to meet stricter environmental initiatives and reduce water and energy use that was previously wasted –
delivering quantifiably better results.
The Intelligent Process-Cooling Solution – Flexibility
Originally introduced to the plastics industry by Frigel more than 50 years ago, proven IPC technology (Fig. 1) describes the use of Frigel’s internationally patented closed-loop adiabatic fluid cooler located outside the facility working in tandem with small, dedicated chillers near each process or work cell as may be required for minor cold-water uses. The result is more flexibility and numerous advantages. In addition, this design concept is modular and can grow as needed for expansions.
When compared with an evaporative cooling tower, the adiabatic-fluid cooler can lower water consumption by as much as 95% and minimize maintenance issues. As a closed-loop system, the continuous supply of clean water reduces chemical use by as much as 40%, meeting stringent municipal water-quality regulations while ensuring consistent furnace performance, helping to improve system reliability and uptime.
Differing from dry coolers, the combination adiabatic fluid cooler and dedicated chillers provide cooling-water temperatures across a wider range of ambient conditions. It also leverages the use of free cooling to achieve an energy cost reduction of up to 80%. Free cooling occurs when the fluid cooler can achieve temperatures required by the components that need cold water. When this happens, the localized chiller compressors will automatically shut down, resulting in significant energy savings.
Unlike centralized chillers, the adiabatic fluid cooler and dedicated chillers together provide more flexibility when it comes to temperature control, so there is no energy wasted. The energy savings can be even more substantial given the ability to capitalize on free cooling.
Frigel’s closed-loop system also eliminates the need for glycol and results in zero bleed-off to drain, resulting in significant environmental benefits. It also enhances heat-treating operations’ ability to meet strict environmental and local regulations.
Other key advantages of the system are reduced maintenance, improved consistency in furnace efficiency and temperature control. The bottom line is the ability to lower operational costs. Additionally, no one wants to invest capital in process-cooling systems unless it is absolutely needed. So, when the investment is necessary, it is best to select a process-cooling technology that provides the greatest opportunity for success.
As with any technology, numerous factors must be considered when an IPC system is tailored for each individual application.
- System sizing: A full evaluation of the cooling load is required. The process temperature to be maintained at each use point in the heat-treating cell must be considered. Ideally, the system should provide 15-20% more capacity than needed to account for scaled or corroded heat-exchanger surfaces.
- Plant location: Ambient conditions play an important role in system performance. All things being equal, a plant located in a cooler climate will call for less mechanical cooling capacity – and the ability to leverage free cooling – compared to a plant located in a warmer one. As a result, plant location will influence the decision.
- Future plans: System design should reflect the potential need for additional cooling capacity. This will allow for greater ease in plant expansions, ensuring future process-cooling needs will be met as efficiently and cost-effectively as possible.
- Available footprint: Although the closed-loop system is designed as a space saver, it’s important to determine the availability of space for a process-cooling system. Acceptable noise levels, requirements for UL-listed electrical panels and other significant details should factor into determining placement of the system and equipment selections.
IPC solutions continue to evolve to give heat-treating operations the ability to easily and effectively manage their systems while also ensuring they deliver optimal performance and the best possible return on the investment. Heat-treating decision makers must factor in a number of technological considerations when vetting the system best matched to their application and goals.
- Controls: Master controllers have been designed to automatically optimize systems while providing the ability to monitor, collect and evaluate data from each process-cooling component. Additionally, the evolution of individual controls on some chillers facilitates the ability to record and monitor the energy consumption of individual units, with access to real-time data.
- Modularity: A self-contained modular system expedites installation, reducing downtime lost to work associated with expanding systems.
- Maintenance: Not all closed-loop central adiabatic coolers (Fig. 2) are the same. In the adiabatic chamber of an advanced system, a fine mist of water is pulsed into the incoming air stream during high ambient-temperature conditions. The mist evaporates instantly, cooling the air before it impinges on the cooling coils that carry the process water. The process drops the temperature at or below the setpoint. Cooled water is then recirculated to the dedicated, smaller chillers
(Fig. 3). A microprocessor-based controller automatically maintains targeted cooling temperatures. As a result, maintenance-related issues due to corrosion are essentially eliminated.
- Protective materials: System materials vary depending on the supplier. Therefore, the materials used to construct the systems should be considered based on the plant’s environment to ensure the greatest protection against the elements for the process-cooling system. Investing upfront in a system built with protective materials will save money in the long run.
- Functionality in tight spaces: An adiabatic fluid cooler typically consumes more space than an open evaporative cooling tower having a comparable cooling capacity. Extended legs that elevate the fluid cooler to provide ample airflow and roof panels that allow multiple cooling units to be placed more closely together are options to help ensure optimized performance when space availability is critical.
It’s All about Optimization
The drive for optimized efficiency is not going away. Equally critical is the need for operations to continue to produce the high-quality parts and products time and again without fail – all while always ensuring profitability. Fortunately, process-cooling technologies have evolved to give heat-treating decision makers more and smarter options to choose from, representing an opportunity that should not be overlooked.