Feature
An example of a plant control room at an industrial facility .
A few key factors for consideration in process temperature control that differ to commercial needs are to address :
• Improvement in the efficiency of a process
• Enhancing the quality of the finished product
• Preventing product spoilage
• Increase the speed of possible production by reducing lag times
• Reducing wear and damage to machinery resulting in reduction of maintenance costs
• Improved safety ( of people , process , machinery , environment ).
Some examples of where temperature control could be critical are in the moulding sector , metal products and machining , engineering work , chemical production , fermentation and distillation , hydraulics , compressed air , engines or motor functions , mineral processing , ovens and smelters – to name but a few .
Additionally , as opposed to comfort cooling applications , process or industrial cooling requires an advanced skillset and understanding , not only for the differing temperatures and physics behind the technology required to meet objectives , but in the knowledge of the number of parameters involved to achieve the goals too .
© RACA Journal | Benjamin Brits
PROCESS TEMPERATURE-CONTROL DESIGN CONSIDERATIONS Temperature control in the industrial world can include various stand-alone or integrated systems to achieve the necessary results . What is of primary importance is the type of facility and the intricacy of what gets carried out at the site . These become the base to determine the types of temperature exchanges that will be incorporated to manage heat / cooling load needs .
Equipment choice ( and system design ) could include a number of options - from direct process control to passing a heating or cooling substance ( water / glycol / refrigerant ) through a secondary circuit , or even the installation of a cooling towertype system .
Some design and equipment selection criteria examples could take the following scenarios into account to reach an acceptable level of efficiency :
• The importance to maintain a constant and precise control of the process temperature
• If control needs to be delivered directly or indirectly to the application source
• What environmental conditions need to be addressed ( inside and outside the facility )
• If system design needs to minimise any potential contamination of the process by adding closed-loop circuits
• If heat reclamation would add value to the site
• What expansion plans are in the pipeline thus leaving options for this to happen seamlessly in future
• What types of capacities need to be negotiated , and for what length of time
• The availability of resources ( such as water and electricity )
• Any potential to tap into free cooling or heating systems
• Etc
It is also not uncommon for industrial systems to operate at a wide range of temperatures – high , medium , low , or ultra-low – depending on the desired result in food and beverage , and conversely other processes may need to deal with extremely high temperature loads such as those used in furnaces or smelting operations where traditional cooling equipment would just not be suitable .
Process cooling systems further are designed to run yearround and depending on their function , are often safeguarded by redundancy strategies and supporting equipment in emergency situations .
For ultra-low temperature requirements , cryogenic technology , which typically uses liquid nitrogen or helium for cooling , is most often used ( dry ice is another option here ). Other uses for low and ultra-low temperature process cooling include freeze drying of products , freezing food , blood and cell storage , and power transmission . These systems require specialty cooling
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RACA Journal I April 2022 www . hvacronline . co . za