Successful operation and maintenance of ceramic filter systems requires a proactive approach. The original design parameters for ceramic filter systems should be correlated to experienced parameters in operation. This exercise will help outline opportunities for system improvements. &nbsp;Operating a ceramic filter system outside of its intended design parameters (e.g., higher static pressure than intended to draw from a furnace) may result in costly operations and maintenance (O&amp;M). The following sections describe key segments of a ceramic filter system and present suggestions for proper O&amp;M.Key Components for O&amp;M Fans&nbsp; Fans for ceramic filter systems operate in high temperatures and static pressures, expounding the requirement for well-executed design and O&amp;M. Fans developed for high temperatures and static pressures have a smaller band of adjustment, oftentimes requiring multiple fans to operate in parallel when high flows and pressures are present and in single-fan operations during lower production ranges. It is paramount to align the fan curves to system flow, temperature and static pressures. This ensures fans do not operate within the stall region of the curve, which is detrimental to fan health and will cause premature failure in fan components along with instruments and equipment connected within proximity to the fans.Hot fans require astute attention to preventative maintenance procedures, including fan bearing and motor greasing, impeller and shaft inspections for debris buildup and corrosion, and periodic vibration analysis. It is suggested to utilize ultrasonic monitors to perform fan bearing greasing. Ultrasonic monitors provide an easily trainable, highly successful way to ensure the correct amount of grease is applied at the correct rates while observing the response of the bearings. It is recommended to be mindful of automatic greasing solutions on the hot fans, as when not designed or operated correctly, they can cause premature and unpredictable failure of fan bearings and components. Grease utilized in the fan bearings should also be reviewed for effectiveness in the application, and grease lubrication amounts and schedules should be developed with respect to the specific lubricant selected. High-temperature synthetic greases can be helpful in elongating the fan bearings’ lifespan, but very detrimental if utilized incorrectly.Ceramic Filters&nbsp; High-temperature, multipollutant control is placed into a neat and easy-to-maintain package in ceramic filters. When operated and maintained correctly, ceramic filters have proven themselves to be a robust solution requiring minimal maintenance, and they’re able to &nbsp;maintain deNOx catalyst life and differential pressure performance over many years.Ceramic filters capture particulate in the nano range, often capturing a variety of particulate that was unexpected and missed in the clients’ specifications. It is recommended to perform waste analysis during the infancy of a system’s operations. This allows for periodic comparisons throughout the life of the system and is an effective tool for root cause analysis when changes occur.Proper design and O&amp;M of reverse-pulse cleaning of ceramic filters are crucial. Pulse cleaning should not be specifically triggered by system differential pressure, but the sequence should pay regard to the development of particulate buildup on the filters (i.e., filter cake). Pulsing too often, not allowing an effective filter cake to develop, can lead to higher system differential pressures overall. The effectiveness of reverse-pulse systems can change drastically in conjunction with changes in production rates. Higher production rates may result in a less powerful reverse-pulse system due to increased face velocity and pressure across the filters. It is advised not to adjust reverse-pulse cleaning parameters without fully understanding the interaction between reverse-pulse design, sorbent injection, process constituents, waste constituents and system flow and temperatures.Periodic ceramic filter testing is recommended annually to plot life expectancy and develop a plan for when the filters should be replaced.Sorbent Injection Systems&nbsp; Operation temperatures of ceramic filter systems correlate directly to peak efficiency ranges of performance hydrated limes, facilitating high removal rates of acid gases. The performance of hydrated limes is highly reactive by design and tends to scale in the storage and transport systems if not well managed. These difficulties can be overcome with proper design and O&amp;M practices. Reward can be found in the following ways:• Operate with minimal velocities to maintain entrainment of the material without fallout. Variable-speed transport blowers and flow sensors shine in this aspect.• Operate with low transport temperatures. High temperatures increase the reactivity of the material and promote scaling in the transport lines prior to injection. Consider heat exchangers after pressure blowers.• Maintain low moisture content in the storage and transport air. All compressed air should be clean and dry. Convey air should be considered for dehumidification.• A sensor for relative humidity in the convey air can help correlate operational experiences to better understand whether humidity control will be beneficial.Preventative maintenance goes a long way in maintaining high uptime and reducing overall maintenance in a hydrated lime transport system. Sensors on the convey system for flow, pressure, temperature and humidity can be integrated with proactive warnings and alarms. Baseline transport pressures and flows of the system with clean transport lines should be recorded. If these pressures and flows are not met, it indicates that there is a clog or scaling of the transport line that needs to be resolved. Failure to resolve plugging as soon as detected will lead to more severe clogging. Severe clogging of hydrated lime transport systems is difficult and time-consuming to resolve.Waste Handling Systems&nbsp; Robust waste handling systems are integral to a ceramic filter system’s success. Process particulate and injected hydrated lime need to be removed from the ceramic filter houses smoothly and without bridging in the housings or clogging in the transport and collection systems. The waste material may still contain reactivity from performance hydrated lime that can cause clogging similar to the sorbent injection system. Airlocks must be designed properly to remove the ingress and egress of air to or from the filter housing to the waste transport system. Air moving to the housings will make it difficult to collect the waste material, potentially creating a condensation point within the housing. Air moving into the waste transport system will bring heat and moisture, which can condense and corrode or plug the system. It is good practice to implement a mass balance tracking system to understand the amount of waste leaving the system relative to sorbents being injected into the system. This mass balance can provide early warnings to trigger reviews before critical damage occurs in the system. Failure of waste transport systems is the leading cause of critical filter breakages.Ammonia/Urea Injection&nbsp; Proper atomization and mixing of the ammonia are important to ensure high deNOx performance. Leading causes of observed ammonia slip or low deNOx performance include eroded injection nozzles, improper ammonia or compressed air pressures, improper mixing in the flue gas and degraded catalyst in the ceramic filters. Injection control loops can also be a concern for deNOx performance. Extractive NOx measurement equipment can delay the response for changes in NOx loading, delaying timely adjustments for ammonia injection. Integrating instruments that can provide instantaneous NOx measurements on the inlet or outlet of the system is a leading solution for proactively controlling and maintaining ammonia injection systems.Control System&nbsp; It is imperative to have a clear and concise graphical control system that utilizes sensors throughout the system for proactive alarms. The control system should include trending features to allow for reviews of the system’s health. Trends are also a leading tool for root cause analysis. With current technology, control systems should be continuously reviewed for improvement. Sensors provide information that can be used in proactive alarms and further expanded with powerful predictive analysis tools to improve the operation and upkeep of a system.Conclusion&nbsp; Ceramic filter systems are a proven method of multipollutant control in biomass and many other markets. With a well-executed operation and maintenance program, these systems are robust, maintaining consistent uptime at low OpEx. If you have a ceramic filter system that is not achieving your expectations, we can work together to resolve the problem.Author: John Wilson&nbsp;&nbsp; Director of Field Operations, Precision Partners&nbsp; john.wilson@ppidg.com

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With a well-executed operation and maintenance program, ceramic filter systems are robust, maintaining consistent uptime at low OpEx. 

Operation and Maintenance of Ceramic Filter Systems

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