Simply save energy and benefit financially quickly!
The energy consumed for compressed air generation is almost completely converted into heat.
A high energy-saving potential - after all, a compressed air station with a power requirement of 75 kW, for example, consumes approx. 300,000 kWh of electricity annually for 4,000 operating hours.
Use this energy - in the form of:
- Hot air to support space heating
- Hot water to support central heating
- Hot water for domestic use
The heated cooling air is used for room heating via a duct system. A controlled, adjustable room temperature is achieved by temperature-controlled dampers.
In winter, the heat of the extract air is used completely or partially for heating purposes.
In summer, it is blown outdoors via an exhaust air duct.
Possible temperature level: 20-25 K above ambient temperature.
Plate heat exchangers are used for heating water preparation. The heating water is guided through "plates" in a closed jacket.
The hot compressor oil flows between the plates and the jacket and transfers its thermal energy to the heating water.
Possible hot water temperature: up to 70° C
The heat recovery process is the same as for heating water. The use of safety heat exchangers prevents the oil from entering the domestic hot water even if there are leaks.
Possible domestic hot water temperature: up to 70° C
ALMiG Kompressoren GmbH, based in Köngen, Germany, is a leading supplier of intelligent compressed air systems. Their cost-effectiveness and energy efficiency make them an important production and profit factor for every customer. Heat recovery offers energy saving potentials that have been underestimated in this context so far. While more and more customers appreciate the advantages of speed-controlled screw compressors, only few think about further synergy effects of their compressed air stations. The use of waste heat is an important starting point here, because the energy consumed during compressed air generation is completely converted into thermal energy. All too often, this energy is discharged unused into the exhaust air, even though it can be used for other purposes, such as supplementing building heating systems or preheating cold water. Approximately 72% of the heat generated in the air compressor is dissipated to the oil in the oil cooler and is ideal for heat recovery.
In the course of a relocation of Kurt Kauffmann Technische Federn GmbH, ALMiG was asked to support the conversion of the existing compressed air system.
During the measurement and analysis of the old system with the ALMiG energy balancing system, it quickly became clear that only a new compressed air system from ALMiG Kompressoren GmbH could offer Kurt Kauffmann Technische Federn GmbH an optimal supply and energy saving potential according to the current state of the art. At that time, the plant consumed more than 800 MWh of electricity per year - an enormous amount of energy, a large part of which can be recovered, thus offering considerable savings potential.
The new compressed air system had to meet all the requirements for operational reliability and at the same time be cost-effective. In addition, the individually adjustable energy-saving potentials such as speed control and heat recovery had to be presented in a clear and quantifiable way so that the holistic energy concept justified the investment in the new compressed air system.
The concept developed by ALMiG not only included a speed-controlled compressor and two other fixed-speed compressors, but also a solution for waste heat utilization and heat recovery. Since a separate room for the compressed air station was already planned during the planning phase of the new production plant, the initial conditions for implementing these options were excellent. The cellar shaft required for the supply air was generously dimensioned so that a sufficient supply of compression and cooling air to the compressors was guaranteed. In addition, all compressors were to be connected to an exhaust air duct. This exhaust duct makes it possible to use a recirculation damper to regulate the temperature of the station seasonally - in winter, the warm exhaust air is used for heating, while in summer it is directed outside to maintain temperatures in the room.
Heat recovery should make an equally important contribution to energy savings. All three compressors were to be equipped with an integrated heat recovery system to utilize a large part of the waste heat from the oil. About 70% of the heat generated during compression should be extracted from the respective oil circuits via plate heat exchangers. The heating water recovered in this way can be fed into the heating system in winter and used to heat sanitary water all year round.
The idea was presented at a meeting with Kurt Kauffmann Technische Federn GmbH. Using ALMiG's own compressed air system, which also has a heat recovery system installed for heating service water, it was possible to demonstrate the concept clearly. A calculation program was also used to simulate the cost savings that can be achieved by using an integrated heat recovery system. Based on factors such as compressor type, rated power, operating hours, desired water temperature and heating oil price, the amount of heated water, the amount of heating oil saved and thus the savings in heating oil costs and the reduction in the CO2 balance can be predicted.
The new compressed air station of Kurt Kauffmann GmbH consists of three screw compressors, two of which run unregulated as base load machines and one speed-regulated machine which covers the compressed air peaks with its variable delivery rate. With the commissioning of the new compressors, an electric ball valve was also installed, which separates the compressed air station from the compressed air network during downtimes and thus further minimizes leakage losses.
This application example illustrates the energy-saving potential of using heat recovery modules and should convince other customers to use this technology in the future. Although it leads to significant monetary savings and contributes to climate protection, the potential of waste heat recovery is little known and rarely used. Since external solutions for heat recovery are also available, it is not even necessary to purchase a new compressor. Customers can also easily retrofit the necessary components and thus save cash and improve their carbon footprint very quickly. Heat recovery is a topic that can be of importance to every user of a compressed air station, especially in view of the expected increases in energy costs. To this end, it is important to discuss the individual situation with the customer in order to implement customized, holistic solutions for each compressed air station.
All necessary components for heat utilisation are already installed during the production of the compressor.
- Simply connect on site and save cash directly!
- Constant temperature control: Depending on the available heat, the customer's water temperature is kept at the desired temperature level.
The compressor is prepared for heat utilisation when newly ordered, i. e.:
- 2 ball valves at the oil tank outlet
- Space requirement for heat exchanger etc. is taken into account in the system
- Water connection openings are already pre-drilled in the panels.
- Later completion with a retrofit kit is possible without effort, i.e.:
- Heat exchanger
- Control valve + temperature sensor
- Hose/pipe connector
Saving money and protecting the environment made easy
Every litre of heating oil you save reduces your CO2 emissions by approx. 2.9 kg. With a 37 kW compressor, you can save almost 20 t of CO2 - this corresponds to the CO2 emissions of a combustion car in 3 years.
Calculation basis: 6,720 l heating oil savings/year with 37 kW compressor and 2,000 h heat utilisation/year x 2.9 kg CO2 = 19.6 t CO2; combustion car: 30,000 km x 7 litres/100 km * 3.14 kg CO2/l = 6.6 t CO2