Due to its specific advantages over steam systems (lower maintenance, no water treatment, precise control and lower investment), thermal oil technology is the first choice for many manufacturing industries for heat transfer and process temperature control. In this article, we present applications from the energy industry.
The energy industry supplies private households and companies in particular with gas and electric power but also with district heating or other fuels. It is facing enormous challenges as part of the energy revolution it is – beside the chemical industry and the agriculture – one of the most important pollutant emitters in the global economy. Furthermore the Federal Government wants to reduce the greenhouse gas emissions by 40 % in comparison to the year 1990. According to experts this is only possible by disconnecting old coal-fired power plants.
The importance of renewable energies is becoming more and more important within the frame of the energy supply: While in 1990 in Germany just under 4 % of the total electricity came from renewable energies, there were already 30 % in 2015. By contrast, the nuclear energy loose relevance: While in 1990 still 28 % of the total gross electricity was won from nuclear energy, the share fell to 14 % by 2015. (Source: German Federal Statistical Office)
In the energy industry, heat transfer plants are used in many fields: Thermal oil systems for example are used for the heating of crude oil tank farms, for gas processing in gas power stations, in combined biomass heating power plants or in solar thermal power plants by means of thermo oil boilers.
Compost has been generated at the composting plant Buetzberg of the Free and Hanseatic City of Hamburg since the mid-1990‘s. In addition to this recycling, the biological waste is to be used also for energy generation in the future. By dry fermentation, biogas will be generated that is made available to the climate-conscious citizen of Hamburg and to the own fleet of Stadtreinigung. heat 11 delivered a complete turn-key thermal oil plant for the heating of the biogas processing plant. The plant mainly consists of one waste heat boiler fired with biomass and a solid fuel incineration plant with automatic fuel supply (including deashing, multi-cyclone dust separator and electrostatic filter) as well as one thermo oil boiler fired with biogas. Secondary and control loops for the heating of separate process zones as well as circulating pumps and containers with fully-automatic control system and remote maintenance complete the innovative solution. The plant serves to provide the heat resulting from the combustion of the green waste for the gas processing of the biogas plant.
Heat transfer plants are used in conventional gas power plants also. For a project in Mexico for example, several fired heaters are used for the heating and drying process of the natural gas before thise can be used for the electricity and steam production.
Waste heat recovery for the generation of electricity
Up to 50 % of the energy used worldwide is lost as waste heat without being used. With thermal oil waste heat boilers, this waste heat – e.g. in combined heat and power units – can very well be used. heat 11 realized already several plants where the heat energy gained in the waste heat boiler serves the heating of an ORC plant. An ORC plant – with an electrical capacity of 1.200 kilowatt for instance – can supply about 3.000 households with environmentally-friendly produced, CO2 neutral electricity which is generated by the combustion of renewable raw materials. At the same time, the waste heat of the ORC process can be used e.g. for wood drying or for provision of district heating.
Tank farm heating
A complete different area of application in the field of energy industry is the heating of crude oil tank farms. So that the viscous crude oil can be transported at all by means of pumps and pipes (e.g. when loading onto tank ships), the large vessels are heated up with thermal oil heating plants. Since these tank farms are often located on the Arabian Peninsula, special requirements are placed to the plant components that must operate reliably at very high humidity, extreme temperature changes and even during sandstorms.
Solar thermal power plants
The world’s largest thermal oil plants can be found in parabolic trough solar power plants in which the irradiation is focused by parabolic-shaped mirrors onto a vacuum-insulated absorber pipe running along the focal line in which a special heat transfer fluid (thermal oil) flows and is heated up to max. 400 °C. The heat transfer oil (thermal oil) gives off the thermal energy via heat exchangers (preheater, evaporator, superheater, reheater) to a conventional water/steam circuit driving a turbine with a generator to produce electricity. Projects in this industry realized by heat 11 are e.g. the Spanish power plants “Extresol 3” or “Los Arenales”, for a power plant in Morocco heat 11 recently received the order to supply a heater (to article).
Conclusion: The areas for application for thermal oil plants in the energy industry are manifold. They range from the conventional power generation e.g. in gas power plants to the renewable energies (biomass generation, waste heat recovery, solarthermics). The interface is always the efficient heat transfer system with organic fluids (thermal oils).