When it comes to generating electricity, several different methods can be used.

In a steam power plant, water is boiled and turned into steam, which drives a turbine to create energy. While this is still a popular way to generate electricity, some facilities are starting to use flue gas from coal-fired plants to supplement the steam required for operation.

Here are just a few benefits of using flue gas in this manner.

What Is Flue Gas and How Does It Help a Steam Power Plant?

Flue gas, also known as exhaust gas, stack gas, or particle gas, is the gas that escapes from combustion plants and contains residual substances such as particulate matter (dust), sulphur oxides, nitrogen oxides, and carbon monoxide.

Flue gas heating helps to avoid wasting energy by making use of its heat to warm up the water. The water is converted into steam when it gets too hot and is used in a steam power plant to rotate a turbine and produce electricity.

Flue gas heating can also operate at maximum efficiency, which helps reduce the emission of greenhouse gases.

How Is Flue Gas Used in a Steam Power Plant?

Flue gas heating is also very effective at lowering greenhouse gas emissions.

Before being preheated and finally discharged through chimneys, the flue gases are first passed over an economiser. This uses low-temperature exhaust gases to heat the main exhaust gases.

The economiser consists of a series of tubes filled with a material such as sand or gravel. When the main gases pass through this sand mixture, the hot air produced from steam evaporation is trapped in the tubes by the cooler air.

The tubes are later used to preheat the flue gases before being discharged through chimneys.

The Advantages of Using Flue Gas in a Steam Power Plant

The advantages of using flue gas in a steam power plant are many.

These include reduced waste heat loss, reduced CO2 emissions, and increased efficiency. Flue gas heating maximises the use of energy generated from coal combustion.

It’s like taking full advantage of the energy created by burning coal. Particularly when waste heat is recovered by flue gas heating, a steam plant can operate at high efficiency while minimising CO2 emissions.

A steam plant with flue gas heating achieves the same performance as plants using 100% fresh steam. While this approach does come at a cost, the savings made compared to using fresh water can be substantial.

Flue gas heating also reduces emissions of smog-forming pollution and nitrogen oxides. The nitrogen oxides are converted to nitrogen and oxygen in the air by natural processes.

Using flue gas in a steam power plant can achieve these benefits while still supplying enough steam for the turbine and generating electricity efficiently.

How to Optimise Flue Gas for Your Steam Power Plant?

Flue gas heating in a steam power plant can be optimised by choosing the right system for the job. When deciding on which system to install in your facility, there are several factors to consider:

Which System Will Fit into Your Budget?

Your budget usually determines your flue gas system for your steam power plant.

An optimised system that uses both economisers and flue gas fans can reduce operational costs compared to a system using a single type of technology. For this reason, it’s often best to have a system of economisers, and flue gas fans installed together.

Otherwise, costs will be higher, and your plant will not be able to achieve the same levels of energy efficiency.

Which System Will Meet Your Needs?

Many flue gas systems on the market meet certain criteria but do not meet others.

Knowing which one will best fit the needs of your steam power plant is essential before investing in one. A flue gas heating plant that efficiently supplies steam to the turbine can achieve high electrical efficiency.

Which System Will Be Easy to Maintain?

Because you are running such a big operation in your steam power plant, you will want a system that will be easy to maintain.

This can help to reduce downtime and also reduce your maintenance costs. You should also know that this is a long-term relationship with your plant, and the system you choose should be suitable for your steam power plant.

Flue gas heating can provide maximum performance for your steam power plant while offering optimal levels of energy efficiency. With a controlled coal combustion flue gas and steam flow, turbines can efficiently produce electricity with full exhaust emission control.

A steam power plant using flue gas heating reduces CO2 emissions, saving energy in operating costs. The biggest advantage of using flue gas in a steam power plant is that the gases are heated at lower temperatures to achieve higher efficiency.

Fewer fossil fuels need to be burnt, reducing the plant’s environmental impact.

How Does Flue Gas Help Produce Electricity?

The top of the chimney has a horizontal axis ducted turbine attached to it, which uses the kinetic energy of flue gases to generate power.

To prevent any detrimental effects on the chimney’s performance, the turbine system is placed beyond the chimney exit. The convergent-divergent duct increases flue gas velocity, which improves the turbine’s performance.

Additionally, it serves as an energy recovery system safety cover.

The Environmental Benefits of Using Flue Gas in a Steam Power Plant

Flue gas heating is a more efficient way of using the heat from steam or coal and can help to lower emissions of harmful pollutants.

It is estimated that using flue gas heating in a steam power plant can reduce emissions of nitrogen oxides by 93% and sulphur oxides by 52%. These pollutants are a major problem for the environment, with nitrogen oxide contributing to acid rain and sulphur oxide contributing to particulate matter and smog.

By reducing the levels of these chemicals released by coal plants, flue gas heating can significantly reduce air pollution.

Some of the Drawbacks of Using Flue Gas in a Steam Power Plant

After wet flue gas desulphurisation, high humidity flue gas also produces “gypsum rain,” which is bad for the environment.

Another way of reducing sulphur oxide emissions is partially oxidising coal in a gas generator. This increases efficiency and reduces costs in the use of coal.

However, there is a danger that this process could cause nitrogen oxide emissions to be double or triple. Another drawback of flue gas heating is that it can significantly increase the emission of particulate matter in the air.

This is because coal combustion generates sulphur oxides, which are converted into sulphate particles. When these sulphates enter the air, they are frequently picked up by moist air droplets during atmospheric condensation.

Various chemical substances, which are harmful to your health, are present in flue gases. Carbon monoxide (CO) is one of them, and it can harm your organs.

CO exposure can be lethal if prolonged. Nitrogen dioxide, acidic water vapours, and airborne particles that can irritate your respiratory system are other substances to be concerned about.

Flue gas spills should be avoided at all costs, and the problem should be fixed immediately. Use a qualified heating technician to design and install your heating system.

The system should be maintained and serviced as needed.

How Can Flue Gas Be Used to Improve the Efficiency of a Steam Power Plant?

The chimney base of a steam power plant has the facility’s primary heat recovery system, which collects flue gas heat from the boiler exhaust and uses it to heat the incoming air, thereby improving the boiler’s efficiency.

The facility’s primary heat recovery system operates at a temperature between 90 °C and 120 °C. The temperature ranges for hot water heat recovery are between 70 °C and 90 °C, and for waste heat recovery, between 45 °C and 70 °C.

The facility’s primary heat recovery system can transfer up to 25% of the boiler’s heat, making it the most important heating system in a steam power plant. Flue gas improves the productivity of a steam power plant because it generates steam (water vapour) while firing all fuel particles at the same time.

The Future of Flue Gas and the Steam Power Industry

Flue gas has a variety of benefits for steam power plants.

It can help optimise the plant for efficiency, reduce emissions, and improve the environment. While flue gas has some drawbacks, the benefits generally outweigh them.

The future of flue gas in the steam power industry is bright, and we encourage you to explore how it could benefit your business.