Features of fuel cell
The distributed fuel cell demonstration power station uses natural gas as fuel. The natural gas is first converted into hydrogen, which is then sent to the fuel cell generator set to produce electricity and hot water.
In principle, as long as the fuel cell continuously inputs reactants and discharges reaction products, it can generate electricity continuously. When the supply is interrupted, the power generation process will end. The main input fuel is hydrogen, and the main output product is water. Compared with traditional power generation technologies, fuel cells have the following characteristics:
(1) High energy conversion efficiency. The chemical energy of the fuel is directly converted into electric energy without a combustion process, so it is not restricted by the Carnot cycle. At present, the fuel-to-electricity conversion efficiency of the fuel cell system is 45%~60%, while the efficiency of thermal power and nuclear power is 30%~40%.
(2) Less polluting emissions. There is no combustion process, almost no nitrogen, sulfur oxides, and no solid dust. The emission of CO2 is also greatly reduced. Even if natural gas and coal gas are used as fuel, the emission of CO2 is also reduced by 40% to 60% compared with conventional thermal power plants.
(3) There are no moving parts, high reliability and good operability, with minimal noise.
(4) Wide range of fuel application and flexible construction. Many fuels that can produce hydrogen can be used in fuel cells and have a wide range of resources. The construction of fuel cell power plants is also very flexible, with almost no restrictions on site selection, and with a small footprint, which is very suitable for inland and urban underground applications. Adopting componentized design and modular structure, the construction period of the power station is short (only about 2 months on average), and it is very convenient to expand and increase the capacity.
(5) Fast load response and high operating quality. It can be converted from the lowest power to the rated power in a few seconds, and the power plant can be very close to the load, reducing transmission and transformation line investment and line losses, and effectively improving regional frequency deviation and voltage fluctuations.
In short, fuel cell is an efficient, clean, and convenient power generation device, which is not only suitable for distributed power generation, but also can form a large-capacity central power station, which is extremely attractive to the power industry.
Microturbine
Microturbine is a newly developed small heat engine. Its main characteristics are small size, light weight, fast start-up, high efficiency, and the power range of a single machine is about 25~300kW.
The structure and working principle of microturbines are basically similar to those of large and medium-sized gas turbines. There are many types of fuel, which can be low or high pressure methane, natural gas and other gas, but also diesel, gasoline, kerosene and other fuel oil. Technically, radial impeller machinery and regenerative circulation are mainly used. Figure 1 shows the internal structure of the MT250 microturbine of the Ingersoll Rand Company of the United States. In Figure 1, the air is sent to the fuel chamber and combusted after being pressurized and preheated to produce high-temperature and high-pressure gas, which enters the turbine to expand and perform work, drive the coaxial generator to generate electricity, and drive the coaxial air compressor to pressurize the intake air. The gas after the work is directed back to preheat the compressed air and reuse the waste heat, thereby greatly improving the overall utilization rate of the entire system. The system emits very little waste gas and heat, and has a small environmental impact. It is suitable for independent and decentralized use in schools, hospitals, enterprises and even families, and belongs to a typical distributed power generation system.
