Industrial heating and cooling: helping to build the world

By Benjamin Brits

So many processes and products we never really even think twice about rely on controlled temperature and conditions to come into existence – helped along by various HVACR systems or methodology.

Industrial (also known as process) heating and cooling is the use of technologies and methods to either add heat or remove it in applications such as factories, processing and storage facilities. This requirement is vast and usually accompanies factors to eliminate any negative influences that would impact equipment or products. This requirement may also be to ensure certain safety elements are met and that efficiency and reliability are achieved too.

There is probably not an industrial or manufacturing process today that does not require some involvement of either, or a combination, of HVACR elements in order to meet a specific outcome – be this any form of use of plastic, steel, non-ferrous metals, wood, or any type of minerals. From the steel reinforcing to the aggregate processing equipment that give us buildings, to the components of electronics or the plastic or glass of the lightbulbs around you, even as far as the taps giving us critical potable water – heating and cooling is required in some or other form to create everything we can see and touch that enhances humanity.

To meet manufacturing and processing requirements in a production facility, several considerations have to be made in order to determine the best solution, and most often, this is left up to specialists in the particular field as handling paper dust versus a sawmill operation versus injection moulding equipment versus mineral or gas processing are all very different, and have many layers of complexity. For this reason, it is common that such projects are executed by design and supply professionals geared towards the particular industry segment.

A compressor installation at an industrial food processing facility. Image credit: © RACA Journal | Benjamin Brits

Cooling requirements are, as we know, widespread in both the industrial and commercial sectors. In industrial processes however, the heat load must be managed carefully, and the different aspects of the overall application may require several configurations of heat transfer. In many instances, the integrity of the final product and the process itself are highly reliant on how effective the heat management principles are.

Unlike comfort cooling or building climate control that (simply) regulates the temperature and humidity in a particular space, process cooling is applied when accurate and constant control of temperature within a process or facility is essential. Therefore, system design and equipment must accommodate heating or cooling capacity regardless of changes to the immediate environment, variable heat loads, or flow requirements of the application in question.

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.

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 tower-type 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

Foundries use a significant amount of cooling technology in producing products. Image credit: Enlightening Images | Pixabay

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 year-round 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 devices, piping, instruments and insulation because of the extreme effects on the materials involved.

In most industrial processes the machinery or process itself also generates heat which requires management as protection and to ensure that the product being manufactured is consistent and of the required quality. The process cooling design may be required to cool, heat, extract humidity or regulate process temperatures throughout the facility.

A good visual example of the need for cooling during manufacturing is found in the plastics industry. Where injection machinery heats a plastic polymer, this enables the polymer to be moulded or extruded and cooling assists to speed up production (if the moulds are cooled more quickly, the quicker a new batch can be processed). Similarly, in the blow moulding of plastic films, the temperature control of the extruded film is important, since this affects the quality and thickness of the film.

Cooling equipment can further incorporate air or liquid as the cooling medium in the process which needs precise temperature control. The cooling design often also needs to be very flexible in order to cater for multiple uses.

In addition to the need to be able to maintain different temperature set points during a manufacturing process, “process coolers” have to be able to maintain a stable temperature at the set point despite variations from the process itself.

Factories often have a limited form of ventilation and very rarely a mechanical cooling installation to control the actual indoor climate itself. The resulting workplace conditions therefore may have a negative effect on the comfort and well-being of employees as well as the performance in production, or lead to accidents.

“Technology and best practice knowhow can lead to energy savings of double-digit figures on the operational budget.”

Processes such as printing in the graphic industry, or processing plastic and metals release a lot of heat, gases, vapours and dusts. Owing to these conditions, it is crucial to design an adequate ventilation system for a facility too. Continuous ventilation refreshes the inside air completely, several times an hour. As a result of this ventilation process, the heat, gases, vapours, dusts (and other harmful substances) can continuously be extracted from the space.

When working with materials such as paper or plastic, these materials cannot deteriorate due to incorrect humidity. Correct humidity levels in such applications lower the chances of static charge, dust load and unwanted material deformation is thus minimized. Furthermore, meeting optimal humidity prevents, for example, condensation on those cooled moulds mentioned earlier – which is particularly a requirement for the plastic and rubber industries alike.

Hygiene on the other hand is the top priority in the food and beverage industry. Here supply air is sourced from the “fresh air”, and the outside air can contain all kinds of bacteria and fungi, and so design must account for such process requirements. Some experts believe using fresh air without pre-treatment raises the risks in product contamination. This would be relevant where processes could not achieve consistency owing to such influences.

For all industrial applications, a stable temperature is always desirable and especially important when working with a high precision production. Another example is working with materials that require stability owing to the exact tolerances which come under pressure when temperatures fluctuate. Similarly in the pharmaceutical industry this would remain true, as well as dairy as another example during heat treatments.

Naturally machines and processes would perform better in a well-balanced climate and adequate system management is in place.

Energy efficiency has become key

Until recently, industrial cooling systems have managed to fly under the “climate change radar” according to UNIDO reports. When it comes to energy efficiency most people tend to think of energy in terms of heat, light or transport. However, cooling systems are ironically emerging as one of the leading contributors to global warming.

Given the statistics of late, it is imperative for industry to pay more attention to the growing demand that is cooling. Simple and low-cost cooling system-optimisation can dramatically reduce energy consumption, and therefore emissions, as a result in the industrial space.

Aside from the multiple environmental benefits that come from cooling system optimisation, current state-of-the-art technology and best practice knowhow can lead to energy savings of double-digit figures on the operational budget for facilities, and so several global bodies have developed a focus to unlock the huge energy saving potential within the cooling sector’s scope.

Various global reports released to date indicate that the industrial sectors of a country’s energy demand can reach in excess of 30% of total generation capacity. Of importance in this equation is that depending on the facility operations, of that already-high figure, cooling functions can occupy up to 50% of those values.

Many countries have yet to establish, let alone regulate standards around industrial processes – thus leaving significant opportunity for such sectors to play a role in reduction of carbon emissions and climate change impacts. So, service providers to these industries – through design methodologies – can ensure a good outcome. To date, standards have focussed more towards HVAC products used in comfort cooling scenarios.

Process temperature control equipment regulations are also difficult to negotiate because of the generally unique conditions around each industry process and the volumes involved in facility establishment. System efficiency and environmental impacts in terms of cooling and facility versus process emissions themselves also become blurred in the evaluation.

Energy efficiency will, however, likely become an extremely important factor in the future of environmental policy, and process temperature controls are likely to incorporate a variety of measurement metrics, the requirement of hybrid-style systems, and incorporation of services as much as possible.

Ventilation and extraction is key in processes that produce any form or gas, dust or vapours. Image credit: Foto Rabe | Pixabay

Technology/equipment in process heating and cooling applications

In most instances the equipment used in process temperature control is a unique combination of technologies and not a “one unit fits all scenario”. Very often this means a solution is custom designed and built around the process and volumes that would be handled. Sometimes standard equipment can be adapted or modified to meet the facility criteria.

Given the fact that processes or facilities can vary from food and drinks to space travel in future, and, be located anywhere from the sea to the desert, industrial equipment and designs must generally be able to meet the toughest conditions and cater to plant sizes from something really compact to installations that are the size of a few rugby fields – all of which require different load calculations and equipment sizing.

The following are some common equipment classes used in this setting:

• Air Handling Units
• Air Movement Equipment
• Ammonia Refrigeration Systems
• Boiler Systems
• Chillers (air and water cooled)
• CO₂ Refrigeration Systems
• Cooling Towers
• Compressors/Condensers
• Cryogenic Systems
• Desiccant Systems
• Ducting and Ventilation
• DX Air Conditioning
• Evaporative Cooling
• Heat Pumps
• Humidification/Dehumidification
• Phase Change Materials and Systems
• Various Heat Exchangers
• Variable Speed Drives

Sources:

1. ASHRAE
2. Cooling Coalition
3. Danfoss
4. Oxy
5. Parker Store
6. Process Cooling
7. UNIDO
8. General industry engagement