Mountings and Accessories of Boilers
Definition
Boiler mountings are the essential fittings installed on a boiler for its safe operation, control, and protection; they are mandatory parts of the boiler.
Boiler accessories are auxiliary devices attached to a boiler system to improve efficiency, steam output, and performance, but they are not absolutely essential for the boiler to operate.
Main Content
1. Boiler Mountings
Safety valve
- This is one of the most important mountings. It automatically opens when the steam pressure inside the boiler exceeds the safe limit, releasing excess steam and preventing explosion. It acts as a safety device and protects both the boiler and the personnel working nearby. In many boilers, spring-loaded or lever safety valves are used.
Water level indicator, pressure gauge, and steam stop valve
- The water level indicator allows the operator to check the water level continuously, preventing low-water or overfilled conditions. The pressure gauge shows the internal steam pressure so that the boiler can be operated within safe limits. The steam stop valve controls the flow of steam from the boiler to the steam main or process line, enabling isolation of the boiler when needed.
2. Boiler Accessories
Superheater and economizer
- A superheater raises the temperature of saturated steam above the saturation point, producing superheated steam with higher energy content and less moisture. This improves turbine efficiency and reduces condensation losses in pipelines. An economizer uses the heat of flue gases to preheat feed water before it enters the boiler, reducing fuel consumption and improving thermal efficiency.
Air preheater and feed pump
- The air preheater recovers heat from exhaust gases to warm the incoming air supplied for combustion. Preheated air improves fuel burning and increases boiler efficiency. The feed pump delivers water into the boiler against internal pressure. It is essential for maintaining continuous water supply and boiler operation. Feed pumps may be steam-driven or motor-driven.
3. Boiler Fittings for Control and Maintenance
Fusible plug and blow-off cock
- The fusible plug is a safety device fitted in the furnace crown or firebox. If the water level falls dangerously low, the plug melts due to excessive heat and allows water and steam to rush in, extinguishing the fire and preventing furnace damage. The blow-off cock is used to discharge mud, scale, and sediment from the boiler bottom, helping maintain cleanliness and preventing corrosion or blockage.
Manhole, mud box, and feed check valve
- The manhole provides access for inspection, cleaning, and maintenance inside the boiler. The mud box collects impurities and sediment from feed water before it enters the boiler system. The feed check valve permits water to enter the boiler but prevents reverse flow, ensuring one-way movement and protecting the feed line and pump.
Working / Process
1. Steam generation and pressure control
- Water is supplied to the boiler through the feed pump and feed check valve. As fuel burns in the furnace, heat is transferred to the water and steam is generated. Mountings such as the pressure gauge and safety valve continuously monitor and control the pressure. If pressure rises too high, the safety valve automatically releases steam to maintain safe operation.
2. Steam improvement and heat recovery
- After steam is generated, accessories like the superheater increase its temperature and dryness. Exhaust flue gases pass through the economizer and air preheater, transferring waste heat to feed water and incoming air. This process improves thermal efficiency, reduces fuel usage, and increases the amount of usable energy from the same quantity of fuel.
3. Operation, cleaning, and protection
- Devices such as the water level indicator, blow-off cock, fusible plug, and manhole help in supervision, maintenance, and safety. The operator checks water level, removes deposits through the blow-off cock, and uses the manhole for internal inspection. If abnormal heating occurs due to low water level, the fusible plug melts and prevents severe furnace damage.
Advantages / Applications
Improved safety
- Mountings such as the safety valve, fusible plug, and pressure gauge protect the boiler from overpressure, overheating, and accidents.
Higher efficiency
- Accessories like the economizer, superheater, and air preheater recover waste heat and reduce fuel consumption, making the boiler more economical.
Better steam quality and reliability
- Steam delivered from a boiler fitted with accessories is drier, hotter, and more suitable for power generation, heating, and industrial processing.
Applications in industry
- These devices are widely used in thermal power plants, chemical plants, paper mills, textile industries, refineries, and steam-based heating systems.
Summary
- Boiler mountings are essential safety and control fittings.
- Boiler accessories improve boiler efficiency and performance.
- Proper selection and maintenance of these devices are necessary for safe and economical boiler operation.
- Mountings and accessories together make the boiler suitable for industrial use and reliable steam production.