Stock Approach - Deaeration

Entrained air in the dilute stock supplied to the headbox of a paper or board machine can cause problems with drainage, foam, sheet formation, and overall process stability. Therefore, mechanical deaeration is sometimes required. This module will identify four ways to keep entrained air out of paper and board making processes and describe the three ways mechanical deaerators remove air from stock.

•List and describe three forms of entrained air in stock suspensions and white water •Identify four ways to keep entrained air out of paper and board making processes •Identify the negative effects of, and potential benefits of removing, entrained air in stock •Identify and describe the key equipment •Identify and describe primary process flows •Describe the three ways mechanical deaerators remove air from stock •Explain why a stand-alone deaerator might be used instead of a combination cleaner/deaerator •Describe the function of the condenser and vacuum device in the vacuum system •Identify potential causes for a sudden drop in vacuum, deaerator flooding, and low vacuum or system instability