Energy Recovery for Air Compressors

Air compressors are heavy energy users, making up approximately 10 per cent of industrial power consumption.

The rising cost of energy is an unpleasant reality facing businesses. This trend is expected to continue for a while. Also, the potential environmental impact of energy production and energy use is strictly regulated. Carbon dioxide (CO2) emission regulations are expected to become stricter, too. This makes it necessary to do everything possible to reduce your operational environmental footprint.

Waste heat emitted from air compressors accounts for approximately 90% of the input energy, making efficient recovery systems essential for cost savings and environmental compliance.

Understanding Energy Recovery

The idea behind heat recovery systems is that they capture hot air expelled from the air compressor. Once processed, output is utilised to reduce energy costs elsewhere in the plant, building, or third-party location.

Heat recovery does not directly reduce the energy required to power a compressed air system. Instead, captured compression heat is supplied elsewhere for heating and other purposes. As a result, it reduces the total energy bill and the carbon footprint.

Modern air compressors, such as oil-free and rotary screw compressors, often come with integrated recovery options that simplify implementation.

The two primary energy recovery methods are water heating and space heating:

Water Pre-Heating

Water heating is the first method to make use of waste heat. This is sometimes called water pre-heating because it reduces water heating expenditures.

Typically, a water boiler heats cold water received at the plant. Instead, a water/oil heat exchanger captures the excess heat and applies it to the cold water feed. To achieve this, the system either uses an existing heat exchanger inside the compressor or an exchanger is separately added.

Pre-heated water passes through to the boiler when using a heat recovery system, so the boiler rarely needs to heat the water because the recovery system has done its job, resulting in considerable energy savings.

Once at the required temperature, the water is supplied through pipes to bathrooms, radiators, or the production line.

When paired with variable speed compressors, space heating systems can optimise heat output, matching real-time demands and avoiding energy waste.

There are a couple of things to consider here:

  1. It is better if the compressor and boiler are close to each other.
  2. Greater cost savings are achieved when hot water is regularly required.

Space Heating

Space heating is the second method where heat recovery technology proves useful. 

Originating from modern air compressors, captured hot air is distributed to the overhead ducting system. These ducts snake around the workshop or factory floor, supplying warm air to the occupants. 

Air compressors are pre-filtered so there are no contaminants. This approach reduces reliance on space heating systems, cutting long-term heating expenses. On naturally warmer days, the system is switched to duct the hot air externally.

There are a couple of things to consider here:

  1. It is better if the ductwork and air compressor are close to each other – this reduces ducting expenses and potential heat loss.
  2. Cost savings are achieved only on colder days.
Energy Recovery for Air Compressors
Energy Recovery for Air Compressors

Benefits of Energy Recovery

Implementing an air compressor heat recovery system offers significant advantages in terms of cost efficiency, environmental impact, and operational performance.

Cost Efficiency: Air compression generates a substantial amount of heat, which can be recovered and converted into useful energy. By using heat recovery systems, businesses can reduce the energy required to heat water or air, leading to significant savings in electricity costs and overall operating expenses. This also reduces the need for additional components like separate heating systems.

Advanced recovery systems ensure nearly 100% utilisation of waste heat, making them cost-effective for high-demand applications.

Environmental Sustainability: By converting waste heat from the compressor into usable energy, such as for a central heating system or hot water system, businesses can significantly reduce their carbon footprint. This aligns with stricter CO2 emission regulations and promotes a more sustainable operation.

Operational Efficiency: Reusing the compressor’s exhaust heat or heat generated during compression improves overall system efficiency. This not only reduces wear and tear on the equipment but also lowers maintenance costs by reducing the load on auxiliary heating systems like fuel oil or natural gas heaters.

Regulatory Compliance: As regulations around energy efficiency tighten, integrating an energy recovery unit helps businesses comply with these standards, avoiding fines and enhancing their reputation as industry leaders.

Energy Resilience: Maximizing the use of recovered heat makes businesses less dependent on external energy supplies, enhancing resilience against energy disruptions. This is particularly beneficial in operations relying on small compressors or water-cooled systems.

In summary, using heat recovery in air compressors is a great way to save energy and reduce operating costs while improving sustainability and operational efficiency. It’s a smart investment for businesses looking to future-proof their operations and reduce their environmental impact.

Implementing Energy Recovery Solutions

Implementing air heat recovery solutions in air compressor systems requires a strategic approach tailored to your specific operation.

System Assessment: Start by evaluating your current air equipment, including energy consumption and the heat generated during the compression process. This assessment helps in identifying the most suitable recovery options, such as PTG heat exchangers for oil-lubricated compressors or simpler systems for air-cooled compressors, where compression heat can be recovered efficiently.

Equipment Selection: Choose the right recovery equipment based on your needs. For instance, a water heat exchanger is ideal for generating hot process water, which can be used across various applications. Alternatively, ducting the air from an air-cooled compressor can provide ambient air heating for space heating. Integrating these solutions with existing systems, like a central heating system, maximizes efficiency and reduces your carbon footprint.

Cost-Benefit Analysis: Conduct a detailed analysis to weigh the upfront investment against long-term savings in energy needed for heating, reduced fuel consumption, and maintenance expenses. Consider how using this recovered heat can contribute to reducing electricity costs and complying with future regulations.

Customization and Maintenance: Customize the solution to fit your specific needs, ensuring it integrates seamlessly with your current setup. Regular monitoring and maintenance are essential to keep the system running efficiently and to ensure that the compression heat converted into usable energy continues to deliver expected savings.

Case Studies

In the push for greater energy efficiency, the latest air compressors consume less energy and provide the highest potential for heat recovery. The power grid supports air compressor energy requirements but alternative energy sources, such as solar or wind power, are viable too.

Energy recovery systems helped a textile manufacturer in the Midlands to capture heat for hot water production. They saved over £30,000 yearly and reduced CO2 emissions by 200,000+ tons annually.

In Northern Ireland, a packaging plant captured enough waste heat from screw compressors to supply free heating to a nearby college. This saved the educational institution over £35,000 annually. Over 190,000 tons of annual CO2 emissions were avoided too.

Additional Example: a food processing plant in Scotland reduced its annual energy costs by 35% by implementing advanced oil-lubricated compressor systems with integrated heat exchangers.

Conclusion

In support of the push to contain rising energy costs and safeguard our planet, air compressor technology is upgradeable. Energy recovery systems, such as heat exchangers, allow industrial manufacturers to capture previously wasted excess heat, and use it.

A detailed plan from J Ll Leach to implement specialised heat recovery equipment permits cost reductions whilst simultaneously reducing harmful emissions. To explore how energy can be recovered, contact us today to see how much your operations might benefit.

By future-proofing your operations with these systems, businesses can remain competitive, sustainable, and compliant with upcoming environmental regulations.

FAQ

What is waste heat recovery in air compressors, and how can it benefit my operations?

Waste heat recovery in air compressors involves capturing the heat generated during the compression of air and converting it into usable energy, such as hot water or space heating. This process can significantly reduce energy costs by using the recovered heat to supplement or replace traditional heating systems, thereby improving overall efficiency and sustainability.

How can the heat generated from air compression be converted into useful energy?

The heat generated during the compression of air is converted into heat that can be used in various applications. For example, a water heat exchanger can convert this heat into hot water with a temperature suitable for industrial processes or space heating. The recovered energy can be a great way to reduce operating costs and carbon footprint.

What are the benefits of using Atlas Copco UK air compressors with integrated heat recovery systems?

Atlas Copco UK air compressors with integrated heat recovery systems are designed to maximize energy efficiency by converting the heat generated during compression into usable energy. This recovered heat can be used to generate hot water or warm cooling mediums, significantly reducing energy consumption and improving operational sustainability.