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The Mystery of Thermal Power Plants: How to Convert High-Temperature Steam into Electricity?
As an important source of global electricity supply, thermal power plants are responsible for producing about 70% of the world's electricity. These power plants use the heat energy generated by various fuels (such as coal, natural gas and nuclear fuel) and transfer it to power generation equipment to achieve electrical energy conversion. However, the scientific principles and engineering techniques involved in this process are little known.
In a thermal power plant, thermal energy is converted into mechanical energy and then into electrical energy, a process that follows a series of thermodynamic cycles.
The working principle of a thermal power plant can be simplified into a few main steps. First, the fuel burns in the boiler to produce high-temperature gases, which in turn heat the water in the boiler to form high-pressure steam. This high pressure steam is then directed to the turbine, where it spins the turbine blades. The rotational motion of the turbine is connected to a generator and further converted into electricity. The efficiency of this process depends on the accuracy of the thermal energy conversion, as well as the quality and characteristics of the fuel used.
Different thermodynamic cycles have different efficiencies, and in the ranking, the Rankine cycle is generally more efficient than other cycles.
For example, the Rankine cycle involves exhausting low-pressure gas to a condenser, where it is cooled and then fed back into the heating process to produce more high-pressure steam. The design of thermal power plants is highly dependent on the energy source they use. In addition to fossil fuels and nuclear energy, more and more power plants are beginning to explore the use of geothermal energy, solar energy and biofuels.
Coal power plants not only generate electricity, but some also use waste heat for industrial heating or seawater desalination, a so-called combined heat and power (CHP) technology, which improves overall efficiency. As technology advances, supercritical and ultra-supercritical thermal power plants have emerged, allowing power plants to operate at higher temperatures and pressures to improve efficiency and reduce emissions.
However, the operation of traditional thermal power plants also brings challenges to the environment: greenhouse gases and harmful substances released by burning fossil fuels continue to affect the global climate.
Faced with environmental issues, carbon capture and storage (CCS) technology has gradually gained attention despite its high implementation costs. Governments and international organizations are also promoting policies to reduce harmful emissions and promote clean energy generation to address the challenges of climate change.
History and Current Status of Thermal Power Generation
Looking back at history, piston steam engines have been used to generate mechanical energy since the 18th century, and the development of steam turbines has greatly improved the efficiency of power generation. In the 1880s, with the patenting of the steam turbine, power plant efficiency improved dramatically, and the traditional piston machines became obsolete.
Currently, renewable energy sources relying on hydropower and wind power are also gradually becoming an important part of the modern power grid.
While thermal power plants still dominate global electricity production, society's demand for renewable energy is increasing. This also drives the transformation of old power plants and their adaptation to a cleaner energy system.
On the technical level, traditional boilers and steam cycles have developed into various forms to suit various needs. For example, in a nuclear power plant, the steam generator is designed specifically for heat exchange to connect two systems: the reactor and the power generation.
These design innovations not only improve operational efficiency but also enhance safety.
In a thermal power plant, the boiler is one of the core components. Its operation consists of a series of high-pressure steel tubes that convert fuel through efficient combustion technology, turning water into high-temperature steam, which in turn drives the turbine.
In addition, the design of the condenser also affects the efficiency of the power plant. Its function is to cool the steam discharged from the turbine and convert it into water, allowing it to re-enter the boiler. The temperature of cooling water directly affects the efficiency of steam condensation, thereby affecting the energy utilization of the entire power plant.
Many thermal power plants now also choose to use recirculating cooling systems, which draw cold water from reservoirs or the ocean to reduce the operating temperature of the condenser, further improving efficiency.
ConclusionWith the increasing importance of renewable energy and environmental policies, thermal power plants are facing pressure to transform. How the future energy structure will balance energy demand and environmental protection goals will be a test for global electricity supply. In this transformation, what role will technological innovation and policy promotion play?
