Boiler accessories are additional components or devices that are installed in a boiler system to enhance its efficiency, performance, or safety. These accessories are not essential for the basic functioning of the boiler but are helpful in improving its overall operation. Two common boiler accessories are the economizer and the superheater. Let's discuss each of them in detail.

1. Economizer:
- An economizer is a heat exchanger device that is used to recover heat from the flue gases leaving the boiler.
- It is typically installed in the exhaust gas path of the boiler system.
- The main purpose of an economizer is to preheat the feedwater entering the boiler.
- By utilizing the waste heat from the flue gases, the economizer helps in improving the overall efficiency of the boiler system.
- It reduces fuel consumption and operating costs by heating the feedwater before it enters the boiler, thereby reducing the energy required to raise the temperature of the water.
- Economizers are commonly used in industrial boilers to maximize energy efficiency and reduce environmental impact.

2. Superheater:
- A superheater is a device used to increase the temperature of steam produced by the boiler.
- It is installed in the path of the flue gases after the primary heating surfaces of the boiler.
- The superheater absorbs heat from the flue gases and further increases the temperature of the steam.
- Superheated steam has several advantages over saturated steam, such as improved thermal efficiency, increased heat transfer, and reduced moisture content.
- Superheaters are commonly used in power plants and other industries where high-temperature steam is required for various processes.
- They enhance the performance and efficiency of the boiler system by providing superheated steam to the steam turbines or other equipment.

3. Stop valve:
- A stop valve is a type of valve used to control the flow of steam or water in a boiler system.
- It is typically installed at the inlet or outlet of the boiler to isolate or regulate the flow of fluid.
- Stop valves are essential for maintenance and safety purposes as they allow the isolation of the boiler from the rest of the system.
- They are used to shut off the flow of steam or water during maintenance or repair work, preventing any accidents or damage.
- Stop valves are designed to withstand high pressure and temperature conditions commonly encountered in boiler systems.

In conclusion, both the economizer and the superheater are boiler accessories that enhance the efficiency and performance of the boiler system. The economizer recovers heat from the flue gases to preheat the feedwater, while the superheater increases the temperature of the steam produced by the boiler. The stop valve, although not directly involved in improving efficiency, is an important accessory for isolating and controlling the flow of fluid in the boiler system.