Proper Maintenance of a Boiler System
This article explains the importance of developing a maintenance schedule for boiler systems and the different parts of the systems that need to be included in the maintenance plan.
The reliance industrial manufacturing has on well-maintained boiler systems is critical. Most obviously, boiler systems provide heating requirements. However, there are also manufacturing activities dependent on what the boiler produces — steam and heat — for safe production, such as in the pharmaceutical and food and beverage industries.
Figure 1. Boiler systems are a critical part of many manufacturing processes. Keeping them well-maintained is crucial.
In the event of a problem with the boiler, production stops and the process breaks down. To avoid a boiler system breakdown and to keep the boiler working with full parameters, companies must plan maintenance activities to keep the boiler running at an optimum level.
Planning ahead for boiler system maintenance allows for the time the boiler takes to cool down to be able to start the maintenance activities. Similarly, after completing maintenance, the boiler takes time to heat up and output steam again. Because of this time commitment, maintenance activities are not executed frequently, making them even more important. It’s better to have boiler maintenance at regular intervals to avoid sudden breakdowns.
Regular Boiler System Maintenance
Advancement in the instrumentation and control components of boiler systems has helped in taking more accurate and complex measurements. The more detailed measurements, the more productive maintenance operators can perform.
Some solutions used in boiler system maintenance measurements include:
- Drum level measurements
- Combustion control systems
- Steam flow measurements
- Gas exhaust analysis
Drum Level Measurements
The drum is the boiler’s fundamental section where conversion from water to steam takes place. Drum measurements include measuring for the correct levels of steam and water.
Figure 2. Single element drum level control. Image courtesy of Schneider Electric.
Level measurement is essential because the drum’s performance and longevity are affected by the uneven portion of the steam and water levels. If the water level is too low, then heat (high temperature) damages the internal structure of the boiler. If the water level is higher than the normal range, the excess water flows through the output, again damaging the respective parts.
Common methods of measuring include utilizing a differential pressure transmitter. Some manufacturers also use guided wave radar technology for better performance.
Combustion Control System
During a routine day, there are times when there is a higher or lower demand for steam. These changing load requirements affect the fuel combustion ability of a boiler. The fuel does not combust fully and wastes uselessly.
To avoid poor fuel combustion, control mechanisms are applied. They assist the boiler in burning the fuel in an optimized way, considering the varying load requirements throughout the boiler operation.
There are two methods of implementing a combustion control system: single point positioning and parallel positioning.
Figure 3. Diagram of single point positioning Image courtesy of Yokogawa.
Single point positioning, also called the jackshaft control method, includes mechanical linkage to control the fuel control valve and airflow damper to the burner. Parallel positioning uses a master pressure controller to control the fuel control valve and airflow damper.
Steam Flow Measurements
During normal factory operations, there can be many levels of requirements put on the boiler system. Feedback of these peaks and troughs should be accurately relayed back to the boiler system, allowing for adjustments in different boiler operations such as combustion control depending on other requirements to ensure safe operation and efficiency.
There are three types of flowmeters commonly used in boilers: differential pressure meters, vortex flowmeters, and Coriolis flowmeters.
Differential pressure measures the change in the pressure as the steam flows through a cross-sectional element such as a nozzle. Vortex flowmeters measure the frequencies created by the vortex as it indicates the steam’s flow. Coriolis flowmeters measure the twist of tubes placed in the path of the steam. The twist indicates the flow of the steam.
Gas Exhaust Analysis
The exhaust gases from the boiler are an adequate source of feedback for the boiler’s performance. By examining the exhaust and studying its contents, we get an understanding of what is going on in the boiler. It also enables us to control emissions — one of the many compliance requirements of regulatory bodies in all parts of the world.
Some common gases analyzed in the exhaust include carbon dioxide, carbon monoxide, and nitrogen oxide.
By continuously monitoring these gases, we can optimally adjust the fuel combustion so that the emissions of these gases are at the minimum level. In addition to environmental factors, poor exhaust quality also has an impact on the health of the boiler.
Benefits of Boiler System Maintenance
Taking shut-down time for boiler system maintenance is not always an easy choice, as it takes time away from production. However, boiler maintenance is an essential job like all other production activities, and cannot be neglected. Let’s look at some of the benefits of proper maintenance.
Maintaining the boiler in working conditions increases the life of the boiler because it finds and removes wear and tear of parts. If a part is faulty, replacing it prevents damage to other parts that are still functioning correctly.
Reduced Energy Costs
Whenever there is a problem with any system or component, the output degrades in terms of quality and capacity. It means more energy is input while the output lags behind. Maintenance keeps things balanced and under control. Any part or system that has undergone maintenance contributes to an enhanced output, avoiding wastage and loss.
Any fault in the boiler system causes reduced output and increased emissions, some of which are dangerous gases for the environment and humans. These emissions are an indicator that the fuel is not fully converting into the desired output.
Moreover, the Environmental Protection Agency obliges industrial units to keep their emissions within a set limit to avoid harm to the environment. Neglecting these set units leads to fines and even longer shutdown periods while the boiler system is brought up to code.
A boiler can be deadly if it is not properly handled because it contains and produces steam and this steam is under immense pressure. Pressurized steam is capable of exploding. Correct maintenance of the boiler helps keep it in a safe condition. Any leak, blockage in the piping or the physical structure, or malfunctioning of components or systems are avoidable by maintaining the boiler regularly.