Ultrasonic measurement of gaseous air in pulp suspensions

Matti Karras, Tapio Pietikainen, Helena Kortelainen, Jouni Tornberg

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)

Abstract

This paper is based on a discovery made in the laboratory during experiments involving ultrasonic interaction in a pulp suspension. Large air bubbles were observed to have only a modest effect on the attenuation of ultrasonic transmissions, while entrained air produced a far more dramatic response. In the case of entrained air, the water-air interface scatters sound strongly. This occurs because of the considerable difference between the acoustic impedances of water (1. 5 multiplied by 10**6 kg/m**2s) and air (4. 3 multiplied by 10**2 kg/m**2s). The entrained air attaches to the fiber flocs in the suspension and scatters sound effectively. The method has been tested in the laboratory and in several paper mills. Tests prove that a commercial meter can be developed to control the feed of chemical defoamer in paper machines.

Original languageEnglish
Pages (from-to)65-69
Number of pages5
JournalTappi Journal
Volume71
Issue number1
Publication statusPublished - Jan 1988
MoE publication typeA1 Journal article-refereed

Fingerprint

Ultrasonic measurement
Pulp
Suspensions
Air
Ultrasonic transmission
Acoustic waves
Acoustic impedance
Water
Ultrasonics
Fibers

Keywords

  • air
  • foams
  • suspensions
  • ultrasonic applications
  • papermaking

Cite this

Karras, M., Pietikainen, T., Kortelainen, H., & Tornberg, J. (1988). Ultrasonic measurement of gaseous air in pulp suspensions. Tappi Journal, 71(1), 65-69.
Karras, Matti ; Pietikainen, Tapio ; Kortelainen, Helena ; Tornberg, Jouni. / Ultrasonic measurement of gaseous air in pulp suspensions. In: Tappi Journal. 1988 ; Vol. 71, No. 1. pp. 65-69.
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Karras, M, Pietikainen, T, Kortelainen, H & Tornberg, J 1988, 'Ultrasonic measurement of gaseous air in pulp suspensions', Tappi Journal, vol. 71, no. 1, pp. 65-69.

Ultrasonic measurement of gaseous air in pulp suspensions. / Karras, Matti; Pietikainen, Tapio; Kortelainen, Helena; Tornberg, Jouni.

In: Tappi Journal, Vol. 71, No. 1, 01.1988, p. 65-69.

Research output: Contribution to journalArticleScientificpeer-review

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Karras M, Pietikainen T, Kortelainen H, Tornberg J. Ultrasonic measurement of gaseous air in pulp suspensions. Tappi Journal. 1988 Jan;71(1):65-69.