Process heat
The term process heat is used in different meanings. On the one hand , it describes the heat that is required for technical processes such as drying , melting or forging , and on the other hand, it also describes waste heat that is released during processes. The term is also often used when both types are linked through heat recovery or in the form of process steam . This article uses the term in the first sense.
Process heat according to temperature range
Process heat is usually divided into the following temperature ranges:
- Below 100 ° C
- Heat transport often with warm / hot water
- 100 ° C to 300 ° C
- Heat transport by means of superheated steam or heat transfer oils ( thermal oils )
- Above 400 ° C, e.g. B .:
- Blast furnaces for steel production
- Industrial furnaces e.g. B. for annealing steel
generation
Most of the process heat is generated by combustion processes ; at best, waste heat can be used as process heat. In addition, process heat can also be obtained in a block-type thermal power station or industrial power station to generate electricity. In 2005, 22% of the process heat in Germany was generated from electrical energy, for example in electrical industrial furnaces. Attempts are also made to provide process heat with special solar collectors ; However, their area of application is limited to drying processes , especially in agriculture.
In addition to an electrical efficiency of 49%, new high-temperature fuel cells also have the advantage of being able to generate process heat of up to 400 degrees.
structure
In 2005, 2415 PJ of process heat were consumed in Germany , which made up 26.3% of the total final energy consumption . 66.2% of this was consumed by industry, 18.2% by households and 15.6% by trade, services and commerce. The process heat was
- 47% from gas
- 22% from electrical energy
- 20% solid fuel
- 9% from heating oil
- 2% from district heating
won. The types of energy are divided up differently between the consumption sectors. While z. B. Solid fuels only play a role in industry, especially as coke in the steel industry, process heat generation in households and businesses is dominated by electricity and gas.
Individual evidence
- ^ Meyer's New Lexicon. Vol. 6, 1980, p. 414.
- ↑ a b Manfred Rudolph, Ulrich Wagner: Energy application technology: ways and techniques for more efficient energy use . Springer, Berlin / Munich 2008, ISBN 978-3-540-79021-1 , Chapter 2: Covering process heat requirements , p. 19–60 ( limited preview in Google Book Search).