Chill Out & Scale Up

In many pilot-plant or production facilities temperature control systems are like a wallflower at the junior high school dance – they are not the most technical, expensive or exciting equipment in the room and are easily overlooked. But, when the most popular person in the class asks the wallflower to dance, everyone notices! Likewise if a problem occurs with the temperature control system the process stops and the repair team dances into action. Actually ‘wallflower’ is a respectable moniker for a chiller; meaning that the chiller performs reliably but by no means belies its importance. Scaled up processes in the pilot or production scale introduce new challenges for temperature control systems. The thermodynamic profile of the process must be thoroughly known with sufficient cooling capacity to reach the desired process conditions.

Typically processes incorporate a capacity safety factor of ~20-30%. Any process cooling applications using tap water should have a thorough cost analysis and environmental impact study conducted. Switching to a recirculating cooler with automated process control and data capture systems increases efficiency and accountability. Keeping the chiller running to the manufacturer’s specifications is crucial for optimal operation and longevity.

ARE YOU TAPPED OUT?
The use of tap water for cooling purposes is common in smallscale operations. However, at the pilot or production scale (>20L) the use of tap water for cooling purposes should be avoided. Tap water temperatures fluctuate greatly throughout the year. The inability to lower temperatures when needed eliminates any capacity safety factor. This lack of cooling capacity control and consistency could lead to a reduction in process efficiency or the potential loss of production. The cost of the water supply/sewer charges weighs significantly in operating budgets. Cooling rotary evaporator condensers is a typical application of recirculating coolers. An average three litre rotary evaporator uses approximately 230,000 litres of cooling water per year. This corresponds to an annual water consumption of a family of four. If the annual costs for cooling water of €2,212.80 (consumption per year 461m3 x costs per m3 €4.80) are compared with the running/operational costs of a recirculating cooler to the amount of €403.20 (consumption per year 2016kW x costs per kWh €0.20), this results in cost savings of €1,809.60 per year. In addition, fresh water is a limited resource with periodic rationing in various locations. If water restrictions activate in your plant area, what do you do? As corporate ‘green’ policies and scrutiny become publicly transparent the unnecessary waste of fresh water exudes environmental irresponsibility. Dedicated recirculating chillers eliminate the waste of fresh water, reduce operating costs and
deliver reliable process control. Large capacity chillers (up to 20kW) can control dedicated cooling processes such as condensers, packaging systems, reaction vessels and semiconductor applications. Circulators with a large pumping capacity (80 l/min, 6 bar) can even control multiple systems when meeting the cooling requirements. Depending on the process, circulators accommodate the use of a variety of fluids for temperature control, including; water, glycols, alcohols, and silicones. Some of these fluids have a lower heat capacity than water allowing the chiller to cool or heat the process faster than water. More importantly chillers offer precise temperature control through a PID controller. Temperature stabilities <±1°C deliver peace of mind that the process temperature conditions remain constant and reproducible.