Measuring and testing – Gas content of a liquid or a solid
Patent
1999-07-06
2000-10-03
Williams, Hezron
Measuring and testing
Gas content of a liquid or a solid
73 9905, 73 5303, 422 681, 422 92, G06F 1546, G01B 2102, G01N 714, G01N 3316
Patent
active
061256889
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for determining the amount of gas contained in liquid. The method according to the invention is particularly well applicable in determining of the amount of gas, both in the form of bubbles and in dissolved state, contained in the various fiber suspensions, i.e. pulps, of the pulp and paper industry. The invention is advantageously applied in control and regulation systems of degassing in the short circulation of a paper machine.
The pulp used in the manufacture of paper, which is normally supposed to contain water, brushed out fibers and required additives, also contains air and other gases depending on the apparatus, the processes and the grade of pulp.
Air entrains into the pulp with high-consistency pulp, circulation waters, pulping and mixing. Also leaking vacuum seals and open turbulent flows introduce air into the process. Chemical and microbiological reactions release gases in the pulp, the most common gas being CO.sub.2. Also other gases may be present such as O.sub.2, SO.sub.2, H.sub.2 S, and Cl.sub.2.
Gas exists in the pulp in two basic forms: as bubble-formed air and as dissolved gas. Bubble-formed air may be divided into free and residual air. Free air means air bubbles moving freely in the liquid between fibers. Residual air is formed when free air is dispersed mechanically for example in a grinder. Microbubbles produced in this way adhere firmly to the surface of the fibers or to the lumen. Dissolved gases constitute various gases dissolved in the liquid, for example CO.sub.2 O.sub.2, N.sub.2, etc. In this form, gases usually do not cause problems and they do not affect the pulp properties but, due to changes in the pressure, the temperature or the chemical balance, dissolved gases may turn into bubbles. The total volume of air varies greatly depending on conditions and the grade of pulp. For example in the head box feed flow, there is normally 1-4% by volume of air.
The most visible influence of air in the paper machine is froth and air bubble on the wire generated by free air. Air in the form of bubbles cause fluctuations in the consistency as air bubbles present in the pulp displace by their volume fibers and water. Residual air has the most significant influence on the pulp properties and the quality of paper. Fibers which contain much residual air are thickened onto an open surface. While moving the fibers bump and adhere to each other. Residual air impedes the operation of a paper machine and degrades the paper quality.
Disturbances caused by air may be avoided by carefully designing the apparatus and processes to prevent air from being mixed into the pulp and/or by removing air entrained in the pulp. Air may be removed advantageously by a DECULATOR.RTM. degassing apparatus by Ahlstrom Machinery Corporation.
A large number of different apparatus, ways and methods for determining the amount of gas present in liquid, both in a dissolved and a gaseous state exist.
DE-B-23 62 158 relates to measuring the amount of gas dissolved in liquid by means of subatmospheric pressure. According to the method of the publication, the sample vessel consisting of a lower container having a pressure air chamber disposed therein and of a measuring tube disposed in the upper portion of the container is filled with the liquid to be measured and the end of the measuring tube is closed. Subsequently, air is withdrawn from the pressure air chamber so as to created a slight subatmospheric pressure in the measuring tube. Due to the subatmospheric pressure, gas is separated from the liquid and the liquid level in the measuring tube decreases indicating the amount of the separated gas. According to the publication, this measurement must be repeated a few times to find out the true volume of gas dissolved in the liquid.
U.S. Pat. No. 4,329,829 relates to measuring the amount of gas bubbles contained in liquid. According to the method described in the publication, a sample of liquid is introduced into a container and it is pressed under two different pressures; between the pr
REFERENCES:
patent: 4164137 (1979-08-01), Williamson
patent: 4184359 (1980-01-01), Gracey
patent: 4329869 (1982-05-01), Toda
patent: 4584866 (1986-04-01), Janssen
patent: 4700561 (1987-10-01), Dougherty
patent: 4730493 (1988-03-01), Lebaud et al.
patent: 4758408 (1988-07-01), Krawetz et al.
patent: 4862729 (1989-09-01), Toda et al.
patent: 4924695 (1990-05-01), Kolpak
patent: 5041990 (1991-08-01), Yabumoto et al.
patent: 5220513 (1993-06-01), Seiden et al.
patent: 5243848 (1993-09-01), Cox et al.
patent: 5285674 (1994-02-01), Strub
patent: 5400641 (1995-03-01), Slemon et al.
patent: 5442948 (1995-08-01), Cowing
patent: 5621161 (1997-04-01), Leyse
patent: 5653250 (1997-08-01), Sigmund et al.
patent: 5932792 (1999-08-01), Dougherty
Andritz-Ahlstrom Oy
Wiggins J. David
Williams Hezron
LandOfFree
Method of determining pulp properties does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of determining pulp properties, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of determining pulp properties will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-184834