Several paper companies manage cogeneration factories where they operate 44 MW gas turbines with high availability requirements (8500 hours/year). In an effort to increase the performance of the gas turbines, Camfil Power Systems was asked to optimize the existing filtration system for three paper factories. The aim of the collaboration was to decrease the total filtration system dP to achieve the following:
• more power output for the same fuel consumption,
• extended filter lifetime,
• less time and effort required for filter replacement, and
• higher engine protection and availability.
The sites are located in coastal to land based conditions, where air quality can be challenging. Relative humidity is moderate to high with an average of 73%, and Camfil‘s Air Analysis team estimated 45μg/m3 PM10 dust concentrations. This is 77% higher than the recommended annual WHO standard1.
The original installations have a 2-stage system design consisting of pleated pre-filters with G4 efficiency, and final filters with F8 efficiency. This system presents the following drawbacks:
• High dP spikes, especially in high humidity, rain, or fog conditions result in:
• Pre-filter replacement every 4 months,
• Final filter replacement every year.
• Low filtration efficiency and no drainage capabilities cause engine degradation.
• Rigid design limits the choice of products for replacement.
Camfil conducted several site surveys to recommend the optimal air filter solution to enhance the performance of the engines. The shortest possible installation time during scheduled maintenance was a fundamental prerequisite. Based on environmental and operational conditions, the OEM and customer decided to upgrade the existing system to a 2-stage static filter solution. The system consists of two air tight filter banks holding the CamFlo Hybrid F7 bag prefilters and the CamGT 3V-600 E10 final filters.
This system has the following advantages:
• low and stable dP, even under wet and humid conditions:
• pre-filter life time expectation > 1 year
• final filter EPA Class life time expectation > 3 years,
• greater engine protection due to EPA efficiency and efficient water drainage, and
• flexible design.
The graph below compares typical pressure drop performance of the previous installation and the Camfil solution. Before the upgrade, pressure drop averaged 3" w.g. (750 Pa), and multiple shutdowns for pre-filter replacement were required throughout the year. The Camfil solution, after one year, maintains a low and stable pressure drop at an average of 1.5" w.g. (375 Pa). As a result, pre-filter replacement decreased to once per year during the plant's annual outage.
The average change in dP between the old and new solution was calculated to be 1.4" w.g. (350 Pa). According to the turbine specifications, an improvement of 1.4" w.g. means an additional 1 300 MWh / yr per plant when running base load (8500 hrs). This solution has produced additional savings for the end user in terms of maintenance and operating costs, as well as superior engine protection and air cleanliness. Additionally, since pressure drop and efficiency class has improved, fuel consumption has also decreased per megawatt hour produced. This means that the carbon intensity is impacted positively by approximately 2% as a result of filtration.
|Average dP||1.4" w.g. (350 Pa)|
|Power output||44 MW|
|Power loss / year||0.25% / 1" w.g. (1.00% / 1 kPa)|
|Operating hours / year||8 500|
|Power savings / year|| 1 300
Increase filter lifetime:
• Prefilter lifetime from 4 months to 1 year
• Final filter class lifetime from 1 year to 3 years
Increase power output:
• Reduce pressure drop by 48%
• Increase power output by 1 300 MWh / year
Increase air inlet quality:
• EPA efficiency decreases engine degradation
• Old solution (year 1): 2.8" w.g. (700 Pa)
• Old solution (year 2): 3.0" w.g. (750 Pa)
• Camfil solution (year 3): 1.5" w.g. (374 Pa)