How Does A Gas Power Plant Work?

A gas power plant is a power plant which produces electricity by using gas. There are many types of natural gas power plants that can generate electricity, but for different purposes. All gas plants use gas turbines. When a stream of natural gas and air enter into the turbine, they burn and expand inside the turbine. Due to the rotation of the turbine, the generator connected with the turbine rotates and creates electricity. According to the 2nd law of thermodynamics, waste heat is generated during this process. 

The installation of the natural gas power plant is very easy and cheap. Compared to other power plants, the gas power plant also has a very high thermodynamic efficiency. The combustion of natural gas generates very low pollution such as SOx and NOx. In contrast, the emissions from natural gas power plant are significantly higher than nuclear power plants. This means that switching from a coal-fired power plant to a natural gas power plant increases air quality (i.e., less smog) but nuclear power improves more air quality.

Although air quality has improved, natural gas installations have made a significant contribution to climate change, and that contribution is increasing (see Pollutants and greenhouse gases). Natural gas power plants produce large amounts of carbon dioxide, but less than coal-fired power plants. On the other hand, when natural gas is transported from the mining area to the power plant, a large amount of methane (natural gas that escapes into the atmosphere) is released. As long as natural gas power plants are used to generate electricity, their emissions will continue to dangerously warm the planet. 

Parts of the Gas Power Plant

Gas Turbine

Gas turbines are used to convert the kinetic energy of hot gas into rotational energy, which is used to power synchronous generators. In addition, there are several levels: high pressure level, medium pressure level and low-pressure level. Since the combustion process takes place inside the turbine, a cooling process is also carried out here to prevent the blades from melting. In most cases, the coolant will continue to flow through the blade.

Compressor

The compressor is a most important part of the gas power plant. It installs on the shaft which compresses normal air and sends it into the combustion chamber. In addition, there are several stages, low pressure stage, medium pressure stage and high-pressure stage, in order to improve the efficiency.

Combustion Chamber

This is where compressed air enters and mixes with the fuel. Then it lights up here and increases the temperature and pressure. Temperatures can rise to 1400 ° C. At this very high temperature, nitrogen can combine with oxygen to form nitrogen oxides, which are controlled so that all of the oxygen is used in the combustion process.

Types of Gas Power Plants

There are two types of natural gas power plants: simple gas power plants and gas combined cycle power plants. The first consists of a gas turbine connected to a generator, and the second consists of a simple cycle device that works on the Rankine cycle and another external internal combustion engine, due to that it is known as “combine cycle”.

  1. Simple cycles are simpler but less efficient than compound cycles. However, simple circular power plants can be delivered faster than coal or nuclear power plants. This allows them to be opened and closed more quickly to meet society’s electricity needs. Wind and solar power are often connected to the grid to generate electricity to meet society’s changing electricity needs, called peak power. 
  2. Combination cycle gas power plants are more efficient because they use the hot exhaust gases from the system. This exhaust gas is used to boil water and turn it into steam. The steam can turn another turbine to generate more electricity.
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