An ORC power module is shown here.With the ORC process it is possible to efficiently turn any kind of low-temperatureheat source into electricity,
In industrial processes such as steel,glass and cement factories, in stationary
piston engines for heavy or light fuel oil,or in small gas turbines there are vast quantities of waste heat at 350° up to 500°C — and small, unused power outputs that are emitted into the environment.GMK, a German company, is offering what it claims is a solution to the issue of turning large quantities of waste heat into electricity.
According to the company, the problem with using those heat sources is that they can’t be utilized for heating purposes. Furthermore, they are unusable by the regular water steam power process based on its physical properties,its specific investment costs and the personnel expenditure, GMK said.
The company claimed that its INDUCAL ORC modules offer a solution,based on the Organic-Rankine-Cycle (ORC) process, to efficiently turn these waste heat potentials into electricity.In the ORC process, an organic medium with a lower boiling point than water is used as a working substance instead of water, such as in the regular water steam cycle.
Due to this considerable difference, with the ORC process it is possible to efficiently turn any kind of low-temperature heat source into electricity, according to the company.
For example, the company said that the heat from the exhaust of a diesel engine is transferred to the ORC module by a thermal oil heat exchanger. This additional cycle makes it possible to collect the heat energy from more than one heat source and transfer it to the evaporator of the INDUCAL plant. By charging the ORC fluid with the highly energetic thermal oil, it evaporates and flows into the ORC turbine where it relaxes and performs work.
The mechanical work is transferred into electricity by a generator. The gaseous ORC medium flows from the ORC turbine into the internal recuperator (in the secondary cycle)where it passes its residual energy to the already liquefied working fluid.Afterward, the gaseous ORC medium is reduced into a liquid state in the condenser.Due to the fact that the condensation heat is not needed or unusable,most of the time the ambient air temperature determines the condensation temperature level, GMK reported.
By choosing suitable working mediums,an optimal use of the heat source is made possible. Therefore, the electrical efficiency of INDUCAL ORC modules for usual applications, such as the electrification of thermal energy from engine exhaust gas, is as high as 20%.
The smallest size of INDUCAL ORC modules with turbines is 500 kWe based on economical cost types; therefore,a thermal heat source with approximately 2500 kW has to be available.According to the company, not only is a high efficiency achieved by choosing the right working fluids, but also a low-pressure process that enables a fully automated operation of INDUCAL ORC plants.
The modules are economical with worldwide small payback periods by producing an additional 10% of power output of the target power plant without using any more fuel, GMK said.
The modules are skid mounted, which allows a simple mounting on-site,where only connections to the cooling,thermal oil and electrical cycle have to be made.