Fuel and ash handling, draught system, feed water treatment

Introduction

Fuel and ash handling, draught system, and feed water treatment are crucial aspects of power plant engineering. These systems play a vital role in the efficient and safe operation of power plants. In this article, we will explore the fundamentals of fuel and ash handling, draught system, and feed water treatment, their components, and their significance in power plants.

Fuel and Ash Handling

Fuel and ash handling involves the management and transportation of fuels used in power plants, as well as the handling and disposal of ash generated during the combustion process. Different types of fuels, such as coal, oil, and gas, are used in power plants. Each fuel type requires specific handling systems to ensure efficient combustion and minimize environmental impact.

Fuel Handling Systems

Coal Handling System

Coal is one of the most commonly used fuels in power plants. The coal handling system consists of various components, including:

1. Coal storage and transportation
2. Coal crushers
3. Coal mills
4. Coal feeders

The coal handling system ensures the proper supply of coal to the combustion chamber for efficient combustion.

Oil Handling System

Oil is another fuel option for power plants. The oil handling system includes:

1. Oil storage and transportation
2. Oil pumps
3. Oil heaters
4. Oil burners

The oil handling system provides a reliable and efficient supply of oil for combustion.

Gas Handling System

Gas-fired power plants utilize natural gas as a fuel source. The gas handling system comprises:

1. Gas storage and transportation
2. Gas turbines
3. Gas burners

The gas handling system ensures the proper supply and combustion of natural gas in power plants.

Ash Handling Systems

During the combustion process, ash is generated as a byproduct. Ash handling systems are responsible for collecting, transporting, and disposing of ash. There are two main types of ash:

Bottom Ash Handling

Bottom ash is the heavier ash that falls to the bottom of the combustion chamber. It is collected using ash hoppers and transported to ash storage facilities.

Fly Ash Handling

Fly ash is the lighter ash that is carried away by the flue gases. It is collected using electrostatic precipitators or bag filters. Fly ash can be utilized in various applications, such as cement production and construction materials.

Advantages and Disadvantages of Fuel and Ash Handling Systems

Fuel and ash handling systems offer several advantages, including:

• Efficient fuel supply
• Proper combustion control
• Environmental compliance

However, these systems also have some disadvantages, such as:

• High initial investment
• Maintenance requirements
• Environmental challenges associated with ash disposal

Draught System

The draught system is responsible for creating and maintaining a flow of air or gas through the combustion chamber. It ensures proper combustion and efficient heat transfer. There are two main types of draught systems:

Natural Draught System

The natural draught system utilizes the natural pressure difference between the atmosphere and the combustion chamber to create airflow. It relies on the height of the chimney and the temperature difference between the inside and outside of the chimney.

Mechanical Draught System

The mechanical draught system uses mechanical devices, such as fans or blowers, to create airflow. It provides better control over the draught and can be adjusted based on the power plant's requirements.

Components of a Draught System

A draught system consists of the following components:

Chimney

The chimney is a tall structure that provides the necessary height for the natural draught system or houses the fans or blowers in a mechanical draught system. It helps create the required pressure difference for airflow.

Fans or Blowers

Fans or blowers are mechanical devices that generate airflow in the combustion chamber. They can be driven by electric motors or steam turbines, depending on the power plant's configuration.

Dampers

Dampers are adjustable plates or valves that control the airflow in the draught system. They can be used to regulate the draught intensity and maintain optimal combustion conditions.

Calculation of Draught Requirements

The draught requirements for a power plant depend on various factors, including the type of fuel, combustion chamber design, and desired combustion efficiency. The draught can be calculated using mathematical equations and empirical formulas.

Advantages and Disadvantages of Draught Systems

Draught systems offer several advantages, such as:

• Improved combustion efficiency
• Better control over combustion conditions
• Flexibility in power plant design

However, they also have some disadvantages, including:

• Energy consumption by fans or blowers
• Maintenance requirements for mechanical components

Feed Water Treatment

Feed water treatment is essential to ensure the quality and purity of water used in power plants. Impurities in the feed water can cause corrosion, scaling, and other operational issues. The feed water treatment process involves the removal of impurities to protect the boiler and other equipment.

Importance of Feed Water Treatment

Feed water treatment is crucial for the following reasons:

• Prevents corrosion and scaling
• Improves heat transfer efficiency
• Extends the lifespan of equipment

Sources of Feed Water

The feed water used in power plants can come from various sources, including rivers, lakes, and underground wells. It may contain impurities such as suspended solids, dissolved minerals, organic matter, and gases.

Impurities in Feed Water

The impurities commonly found in feed water include:

• Suspended solids
• Dissolved minerals (e.g., calcium, magnesium)
• Organic matter
• Gases (e.g., oxygen, carbon dioxide)

Methods of Feed Water Treatment

To remove impurities from feed water, various treatment methods are employed:

Filtration

Filtration involves the removal of suspended solids using filters or screens. It helps reduce the risk of equipment fouling and improves water clarity.

Softening

Softening is the process of removing dissolved minerals, primarily calcium and magnesium ions, which cause scaling. It can be achieved through ion exchange or chemical precipitation.

Demineralization

Demineralization removes all dissolved minerals from the feed water, including ions and salts. It is typically achieved through processes like reverse osmosis or ion exchange.

Deaeration

Deaeration removes dissolved gases, such as oxygen and carbon dioxide, from the feed water. It helps prevent corrosion and improves heat transfer efficiency.

Advantages and Disadvantages of Feed Water Treatment Methods

Feed water treatment methods offer several advantages, including:

• Improved boiler performance
• Reduced maintenance and repair costs
• Extended equipment lifespan

However, these methods also have some disadvantages, such as:

• High initial investment
• Energy consumption
• Chemical handling and disposal

Real-world Applications and Examples

To better understand the practical implementation of fuel and ash handling, draught systems, and feed water treatment, let's explore some real-world applications and examples:

Case Studies

Case studies of power plants can provide insights into the challenges faced in fuel and ash handling, draught systems, and feed water treatment. These case studies may include information on system design, operation, and maintenance.

Examples of Problems and Solutions

Power plants often encounter problems related to fuel and ash handling, draught systems, and feed water treatment. Some common issues include fuel supply disruptions, ash disposal challenges, draught system malfunctions, and water quality issues. These problems can be addressed through proper system design, regular maintenance, and effective troubleshooting.

Conclusion

Fuel and ash handling, draught system, and feed water treatment are integral components of power plant engineering. Understanding the fundamentals and significance of these systems is essential for efficient and safe power plant operation. By implementing appropriate fuel and ash handling systems, draught systems, and feed water treatment methods, power plants can optimize combustion, minimize environmental impact, and ensure the longevity of equipment.

Summary

Fuel and ash handling, draught system, and feed water treatment are crucial aspects of power plant engineering. Fuel and ash handling involve the management and transportation of fuels used in power plants, as well as the handling and disposal of ash generated during the combustion process. Different types of fuels, such as coal, oil, and gas, require specific handling systems. The draught system is responsible for creating and maintaining airflow through the combustion chamber, ensuring proper combustion and efficient heat transfer. It can be natural or mechanical, with components like chimneys, fans or blowers, and dampers. Feed water treatment is essential to remove impurities from the water used in power plants, preventing corrosion, scaling, and other operational issues. Methods like filtration, softening, demineralization, and deaeration are used to treat feed water. While these systems offer advantages like efficient fuel supply, improved combustion efficiency, and improved boiler performance, they also have disadvantages like high initial investment and maintenance requirements.

Analogy

Imagine a power plant as a human body. Fuel and ash handling can be compared to the digestive system, where different types of fuels are ingested and processed, and the ash generated is eliminated. The draught system can be likened to the respiratory system, ensuring a continuous flow of air or gas through the combustion chamber. Feed water treatment is similar to the purification process in the body, removing impurities from the water to protect the boiler and other equipment.