(PresseBox) Due to high energy costs and increasing environmental awareness, companies are forced to optimise their processes and to use their resources more economically and efficiently. From an economic point of view, the application of heat recovery by using process heat is getting more and more attractive. Now, AERZEN offers innovative solution concepts, in order to reduce energy costs on a sustained basis. Savings of more than 90% are easily possible!
Decreasing fossil sources of energy and increasing energy consumption do not only require more investments in technologies for renewable energies, such as wind, sun, geothermal energy and biologically renewable resources, they also entail growth of future strategic markets. Especially in case of process air generation, energy savings are very important, as the lion’s share of the life-cycle costs is the consumption of electrical energy. For thermo-dynamical reasons, in case of compressed air applications, heat is generated (electrical energy of the drive power is converted into heat). This heat arises as waste heat from motor, compressor and silencer, but it is also generated when process gas temperature increases. However, in many cases, this heat is lost without being used.
In principle, there are two possibilities of heat recovery upon operation of positive displacement blowers, screw and rotary lobe compressors or turbo machines.
Cooling air for space heating
It can be made good use of the cooling air for the stage, the silencer and the piping under the acoustic hood as well as of the exhaust air of the oil cooler for space heating. Exhaust air channels of the packaged unit bundle waste heat (30° C to 60° C). Then, this air is conveyed as heating air to places where heating is needed. A temperature-controlled outlet ensures a controlled ambient temperature. Depending on the heating period, excess air is released to the outside via an exhaust air channel.
Application of heat exchangers
Another possibility of heat recovery is to benefit from the stored energy of the compressed medium by the application of a heat exchanger. The advantage of this is that the heat is taken from the place where it is generated. Energy losses only arise on the way to the end user. In case of this operating principle, the heated medium passes a heat exchanger that heats the water flowing through to target temperature (only applies to wastewater treatment plant technologies), or which cools the gas down to 50 °C and below (only applies to pneumatics). However, both possibilities require engineering with optimised heat transfer. Consequently, the heated amount of water and its temperature depend on the following: throughput speed of medium in the heat exchanger, pipe bundle length, pipe surface, used materials as well as size of heat exchanger. Depending on the design of the heat exchanger, the heated water can be used as process water. Also with this method of heat recovery, the hot water is fed to a large extent into the heating system. In this way, more than 85% of the heat energy will be recovered.
The generation of process air is energy-efficient and cost saving. However, many plant operators seldom recognise these potential savings. Thanks to low investment costs, expenditures for installation or integration in the company’s process cycle pay off after only a few months. As application specialist, AERZEN offers a pinpoint design of heat exchangers with maximum amount of heat transmitted and at lowest possible pressure loss. Even older compressed-air systems can be energetically optimised and retrofitted. Another advantage: AERZEN offers everything from one source.