Typical Yankee Drying Performance Analysis

After successfully installing a heat recovery system to preheat combustion and make up air, our client requested we conduct a drying performance audit of his Yankee Hood.

The objective of the survey was as follows:
1) Determine the actual performance values of the hood and Yankee cylinder and compare these values to the industry standard.
2) Adjust the balancing of air systems to optimize hood performance while minimizing gas consumption.
3) Make short and long-term recommendations to obtain additional drying capacity and/or reduce energy consumption.

Test and data gathering performed:
A) We perform multiple grab samples of the sheet leaving the pressure roll and entering the wet end hood to determine the sheet dryness at different positions.
B) Collect production information.
C) Record gas burner information.
D) Record hood control settings from DCS.
E) Record positions of the profiling dampers.
F) Record all hood damper positions in the field.
G) Measure pitot traverse for duct flows at multiple points. H) Measure fan and hood pressures.
I) Measure hood humidity for WE and DE hoods.
J) Perform a condensate tank rise test.

Some major findings derived from our Yankee cylinder/hood drying performance analysis:

Yankee air systems are energy intensive and should routinely be checked to ensure that they run at an optimal level. A proper hood balance ensures maximum thermal efficiency (i.e BTU (fuel) per ton of paper). A simple survey allows the papermaker to verify hood performance and balance the air systems. These surveys or audits can often result in significant savings in burner fuel and fan horsepower consumption while providing you with recommendations for future improvements.

Contact our technical service department for a full optimization survey.

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