Common Maintenance Issues of Steam Boiler Drums
The ability to generate steam has sparked the industrial revolution and steam boilers take advantage of this ability. A steam boiler is a pressure vessel in which water is heated and circulated to generate saturated or superheated steam. The set-up has a combustion chamber where fuel and air are fed to generate flue gas. The flue gas travels through heat exchangers, where heat is transferred from hot gases to water. The flue gas finally exits through the stacks. The steam drum is the most expensive component in the boiler. It is considered the heart of the boiler. The drum separates saturated steam from the steam-water mixture. The steam-water mixture is recirculated for further steam generation. The saturated steam exits through nozzles of the steam drum for further processing.
Maintenance of the steam boiler is essential for safe and efficient operations.
The steam drum is a high-pressure vessel. It acts as a temporary storage device and phase separator. The steam is purified with the help of steam drum internals. The different steam separators are:-
- Baffle separators
- Cyclone separators
- Chevron separators
- Demisters/Screen driers
Other components of steam drum include:-
- Feedwater distributor pipe distributes
- Safety valve
- Chemical dosing pipe
- Continuous blowdown pipe.
- Drum level gauge
- Saturated steam outlet pipes
- Intermittent blowdown pipe
Functions Of The Steam Drum
Steam drum is the phase separator of the boiler. Other functions of the steam drum include:-
- Mix the feed water with the steam-water mixture after phase separation.
- Mix the corrosion control and water chemicals.
- Purify the steam from contaminants and moisture.
- Enable continuous and intermediate blowdown of water to control water chemistry.
- Provide limited water storage to account for changes in the boiler load.
The efficiency of the separation is critical for the boiler because:-
- It prevents the water droplet carryover into the superheater. Water droplets can harm the superheater.
- It reduces steam carry under in water leaving the steam drum to reduce the effective hydraulic pumping head.
- It prevents water carryover with dissolved solids entering the superheater and turbine. These deposits can harm the superheater and turbine blade.
Problems While Operating The Steam Drum
The steam drum is the most expensive boiler component. Occurrence of deposits in the steam drum and drum internals can lead to operational problems. Deposits include calcium, magnesium, iron, copper, aluminum, silica, and in rare cases, silt and oil. Drum deposits are classified into:-
- Scale deposits crystalize directly on the drum. Scale forms due to precipitation due to evaporation. The nature of the scale depends on the chemical composition of the concentrated water.
- Sludge deposits occur due to precipitation of the flowing water. Sludge deposits are hard, dense, and highly insulating.
Steam purity is defined by the amount of solid, liquid, or vapor contaminants in the steam. Pure steam contains a negligible amount of impurities. Any solid, liquid, or vapor containment in the steam is known as ‘Carryover’. Carryover can lead to superheater failure due to overheating or corrosion.
Solid particles in the steam can damage the turbine blade. It can also cause critical thermal and mechanical shocks.
Carryover in the process stream can affect final product quality. The use of suitable steam separator equipment is vital to prevent steam contamination. The steam separator may not work optimally in case of deposits.
Improper water treatment can result in foaming and selective vapor carryover. It can cause carryover and incorrect water level readings.
Solving Maintenance Issues Of Steam Drums
- Sample from the continuous blowdown from the steam drum is collected daily. In order to ensure maintenance of steam drum, we regularly check samples for impurities such as dissolved solids that are harmful to the boiler. For proper steam boiler condition, boiler water quality is required. Thus, if the steam has a high amount of carryover, corrective steps should be taken to eliminate deposit formation inside the pressure parts.
- The boiler is shut down, after cooling the boiler down. The deposits are removed from the steam drum and other pressure parts. The drum internals are dismantled and cleaned thoroughly to remove deposits.
- The water treatment is rechecked to ensure the feed water meets the required parameters.
Why Mago Thermal?
- Mago Thermal Private Limited has been providing boiler services for over 20 years. We are an ISO 9001:2000 company. We have designed, manufactured, and commissioned boilers to fire a range of biomass and fossil fuels. MTPL offers a range of boiler models. We recommend our models based on your fuel and process parameters.
- Mago Thermal Private Limited offers EPC solutions for power plants. We provide engineering services for boilers including modernizing, fuel conversion, efficiency improvement, and operation and maintenance services.
- Mago Thermal Private Limited provides operating and maintenance services for steam boilers and power plants. Our experienced staff ensures smooth and efficient running of your boiler or power plant.
- Our diverse experience has helped us solve all problems. Our extensive database and knowledge can help solve problems quickly.
Benefits Of Outsourcing Maintenance Of Your Boiler:-
- Power plant or boiler runs efficiently
- Saves operation and fuel costs
- Trained staff operates the boiler.
- There is an experienced backup provided
- Timely maintenance ensuring problems get solved quickly.
- Compliance as per Indian Boiler Regulations.