Coal pulverizer reliability at a glance
Coal particles and wear metals can contaminate pulverizer lubrication systems through worn bearing and shaft seals, reservoir vents and wear metals generated by grinding surfaces. Effective filtration helps maintain oil cleanliness and protect bearings, gears, pumps and seals. Pall recommends a fluid cleanliness level of ISO 16/13 or better.
Why Is Coal Pulverizer Reliability Important?
Coal pulverizers play a critical role in coal-fired power generation. Contamination within lubrication systems can contribute to damage to bearings, gears, pumps and seals, affecting pulverizer reliability and maintenance requirements. Learn how effective contamination control and filtration can help protect critical components and support plant availability.
Coal pulverizers are used to grind coal into a fine powder that can be burned efficiently in the boiler. Pulverizing coal improves combustion efficiency and supports reliable plant operation.
Industry studies cited in the original technical content found that approximately 1% of plant availability was lost on average due to pulverizer-related problems. The same source identified oil contamination and excessive leakage as factors in pulverizer drive-train failures.
Explore additional power generation resources designed to help improve equipment reliability and contamination control.
Coal pulverizer systems convert raw coal into a fine powder for combustion. Effective contamination control helps protect lubrication systems and support reliable pulverizer operation.
How Does Contamination Enter Coal Pulverizer Systems?
Coal pulverizer gearboxes rely on lubricating oil to protect gears and bearings during operation.
Fine coal particles and wear metals can enter the lubrication system through:
- Worn bearing and shaft seals
- Reservoir vents
- Wear metals generated by grinding surfaces
Historically, many pulverizer designs assumed contamination levels would remain manageable through routine operation and maintenance. In practice, contamination ingress can occur at a rate that places critical components at risk.
Why Is Contamination a Problem?
High contamination levels can:
- Reduce bearing, gear, pump and seal life
- Lead to premature replacement or rework
- Increase maintenance requirements
- Reduce pulverizer and plant availability
Maintaining lubrication system cleanliness is therefore essential for helping protect critical pulverizer components.
Why Can OEM Filtration Be a Challenge?
Many coal pulverizer lubrication systems either have no filtration or rely on coarse filtration technologies such as cleanable mesh filters and stacked disk filters.
These systems may struggle to manage the high contamination ingression rates often found in pulverizer applications. As contamination levels increase, lubrication system cleanliness can deteriorate and shorten the life of bearings, gears, pumps and seals.
Older pulverizer installations may be particularly susceptible due to higher contamination ingress rates.
Recommended Filtration for Coal Pulverizers
Maintain ISO 16/13 Fluid Cleanliness
The majority of pulverized coal particles are in the 4–30 μm range, with 70% of these particles smaller than 10 μm.
To help protect coal pulverizer lubrication systems, Pall recommends maintaining a fluid cleanliness level of ISO 16/13 or better.
Athalon® Filter Technology
Pall recommends using Athalon® filter elements in AS grade (β12(c) ≥ 1000), or finer filtration, to help achieve the recommended cleanliness level. Their particle-removal efficiency and dirt-holding capacity are suited to this high-ingression application.
Pall Duplex Assembly
A Pall Duplex Assembly allows filter elements to be changed while the pulverizer remains in operation, helping support maintenance flexibility and continued production.
Kidney Loop Filtration
Where in-line filtration is difficult to implement, kidney loop filtration may be a suitable alternative. Proper system sizing remains important due to the high viscosity of gear oils commonly used in pulverizer applications.
Customer Example: Reduced Coal Pulverizer Downtime
Challenge
In 2003, a major Canadian utility experienced a pulverizer failure that resulted in the derating of Unit 4. With lost production of approximately 864 MWh per day, the total estimated revenue loss was around $2,000,000. Repair costs added up to more than $400,000. Analysis identified poor oil cleanliness as one of several contributing factors.
Solution
Pall supplied a filtration housing for a six-month trial to demonstrate improved oil cleanliness control. During the trial, oil cleanliness improved from ISO 20/19/17 to ISO 18/16/13 in approximately two hours and was maintained at that level.
Results
Following the trial, the plant installed one assembly on each of its 30 coal pulverizers and adopted annual filter element replacement.
Frequently Asked Questions
What is a coal pulverizer?
A coal pulverizer grinds coal into a fine powder so it can be burned more efficiently in boilers used for power generation.
How does contamination enter a coal pulverizer?
Fine coal particles and wear metals can enter lubrication systems through worn bearing and shaft seals, reservoir vents and wear metals generated by grinding surfaces.
Why is filtration important for coal pulverizers?
Filtration helps control contamination that can contribute to bearing, gear, pump and seal damage.
What fluid cleanliness level does Pall recommend?
Pall recommends maintaining a fluid cleanliness level of ISO 16/13 or better for coal pulverizer lubrication systems.
Talk to a Filtration Expert
Coal pulverizer reliability depends on effective contamination control. Pall specialists can help evaluate lubrication system cleanliness and recommend appropriate filtration strategies for pulverizer applications.
Talk to a Filtration Expert