Title of Invention	IMPROVED FOAM MEASURING DEVICE
Abstract	The invention provides for a portable foam-measuring device for the continuous measurement of foam conductivity comprising -a foam cell -plurality of oppositely paired electrodes implanted across the length of the foam cell -an automated foam generating shaker adapted for the foam cell -a tunable current source and -a high-speed data logger system for data acquisition and processing.

Full Text

FORM - 2 THE PATENTS ACT, 1970 (39 Of 1970) & The Patents Rules, 2003 COMPLETE SPECIFICATION (See Section 10 and Rule 13) IMPROVED FOAM MEASURING DEVICE HINDUSTAN LEVER LIMITED, a company incorporated under the Indian Companies Act, 1913 and having its registered office at Hindustan Lever House, 165/166, Backbay Reclamation, Mumbai -400 020, Maharashtra, India The following specification particularly describes the invention and the manner in which it is to be performed. Field of invention The present invention relates to a portable foam-measuring device for the continuous measurement of foam conductivity as a measure of foam stability. The present invention particularly relates to a portable foam-measuring device for the continuous measurement of foam conductivity with the aid of series of oppositely placed electrodes placed along the walls of the foam cell. Background of the invention Foam conductivity is a measure of foam density indicated by the electrical resistance of the draining foam. Gas liquid foams are structured two-phase fluids in which gas bubbles are separated by interconnecting thin liquid films, and the volume fraction of the continuous liquid phase is usually small in dry foams but can be substantial in wet foams. The bubble size ranges from several microns in a fine foam to several millimeters in a coarse foam. Foam finds applications in a wide range of industrial processes including food production, cosmetics, fire fighting, biotechnology, mineral processing, effluent treatment and enhanced oil recovery. Highly stable foams are usually desirable in foam based food and cosmetic products. Alternatively, in many situations persistent foams are undesirable; for example the presence of a substantial foam layer in a bioreactor can lead to serious operating problems in commercial fermentations and a decrease in bioreactor efficiency. In all cases, the stability of the foam can determine both the economic and technical successes of the industrial processes concerned. Foams are thermodynamically unstable structures, as soon as foam forms; it undergoes drainage by capillary and gravitational forces. In many applications the effectiveness of foam is related to its stability and in this respect foam drainage is often used as a diagnostic test. Foam drainage and foam collapse combine to define foam stability but the two processes are distinct and their kinetics are different. Under no external influences, foam drainage precedes foam collapse and hence fast drainage leads to quick onset of foam structure breakdown. The ability to characterize drainage behavior of foams is thus of direct value to the design of foaming systems with specific properties and the control of foam structures. For example in the race to bring new products to the market place there is increasing pressure on food and cosmetics manufacturers to determine the stability of new products reliably and efficiently. New formulations for foams are all tested for stability to access potential shelf life and to confirm they can proceed to the production stage. This stage is generally time consuming and the availability of instruments that can be used reliably to test foams and determine the effects of changes in formulation is extremely valuable. There are a few techniques available for foam drainage measurements. Earlier measurements of foam drainage as reported in J.J.Bikerman, J.M.Perri, R.B. Booth, C.C. Currie, Foams, Springer, Berlin 1973; amounted to crude measurements of liquid drained after a specific time. A recent review of foam drainage by Weaire et al. (Advances in Chemical Physics, vol. 102, Wiley, New York, 1997, pp. 315-374) has reported more recent techniques to measure vertical liquid holdup profiles as a function of time rather than just the drained liquid. Hutzler et al. in Measurement of foam density profiles using AC capacitance, Europhys. Lett. 31(8) (1995) 497-502; used a segmented capacitance resistor, which requires the foam to be non-conducting. The requirement that the foam be non-conducting, the difficulties associated with the calibration and the lack of reproducibility represent serious drawbacks for this method. McCarthy et al. Barigou et al. and Prause et al. investigated the feasibility of Magnetic Resonance Imaging (MRI) to measure density profiles in draining foams. MRI, however, is a high-cost high-skill technique and can usually only allow measurements on a small scale. Various literatures show the successful exploitation of electrical conductivity in characterization in liquid content in electrically conducting foams. Applications have used electrodes which consist of either two parallel plates or two partly stripped wires inserted in the wall of a column filled with foam, and measured the local electrical resistance as a function of time. The measurement of electrical conductivity of the foam as a function of foam drainage and its correlation with foam density has been established for many years and is a useful tool for expressing foam stability. The foam conductivity is continuously monitored for a pre-determined period of time depending on the stability of the sample. The foam conductivity of the sample at time t (Ct) is used to calculate the stability of the sample in the following way: where Co is the initial foam conductivity recorded when the foam had reached the maximum foam level. The electrical conductivity technique is a popular technique to elucidate various aspects of foam drainage. The technique is relatively low cost, easy to use, and is therefore useful for the study of foam drainage behavior being capable of both qualitative and quantitative characterization of various foaming systems. Wildi et al. in J. Colloid Interface Sci. 17 (1996) 733-9 discuss about the foam measurement by the micro conductivity technique. Single pair of oppositely placed electrodes was used to measure the foam conductivity in the foam microconductivity apparatus. The system utilizes presaturated nitrogen gas, forced through the gas jet having a single orifice, to create the foam. The foam properties are measured only on a single interface plane in between a lone pair of electrodes and these results are extrapolated as representative results for the entire model system. Measurement of foam drainage using AC conductivity by Wearie et al., J Physics Condensed Matter 7(16)(1995) L217-L222 discloses AC conductivity measurements used to determine the local liquid fraction in a foam column under conditions of free and forced drainage. The studies are carried out using a lone pair of stripped wire electrodes. The foam is created in the column by blowing nitrogen through a fine glass nozzle. Since lone pair of electrodes was found to be insufficient to characterize the foaming characteristics, attempts were made to use series of electrodes. Cilliers et al., in 1st World Congress on Industrial Process Tomography, Buxton, Greater Manchester, April 14-17,1999 disclosed a study related to the use of Electrical Resistance Tomography (ERT) for exploring the internal structure of a foam column. A cylindrical plastic vessel fitted with a tomographic sensing ring with 16 electrodes was used. Since the electrodes are arranged in a single plane, the data generated although indicated regions with different conductivities, yet the results cannot be used to compare quantitatively the conductivities of these regions. It is known that foam drainage leads to the establishment of non-uniform liquid distribution with liquid holdup decreasing with foam height; hence drainage is initially fastest at the bottom of the foam column and slowest at the top. It is therefore disadvantageous to measure foam drainage using devices mentioned above having single pair of electrodes or series of electrodes at a single plane as it is not indicative of the foaming characteristics of the foam in the entire foam column. These traditional set-ups therefore involve a substantial risk, as the electrical resistance measurements may not give reliable measurements of foam drainage. Barigou et al. in " An enhanced electrical resistance technique for foam drainage measurement", Colloids and Surfaces A: Physicochemical and Engg Aspects, 189 (2001) 237-246 describe an improved electrical resistance technique for measuring drainage of single foam films. The foam columns contain 5 rings, each ring acting as an outer electrode in conjugation with an opposite inner electrode of the same height. The outer electrodes are mounted along the inner wall of the column while the inner electrodes are mounted on a thin non-conducting tube positioned along the central axis of the foam column. The inner and outer electrodes are connected to a multi-channel electrical resistance meter, which is linked to a microcomputer via a data logger for online data acquisition and processing. The foam is created in the column by blowing nitrogen through a fine nozzle. Although this prior art describes plurality of electrodes along the length of the column, the presence of a tube along the central axis of the column on which the inner electrodes are mounted is an intrusive member which can affect the quality of the foam and its strength and stability. The above review of literature has highlighted the need for relatively simple and accurate drainage measurement techniques. The present inventors have found that the foam drainage measurements can be carried out more accurately and in a high-speed manner, which is statistically significant, by the portable device of the present invention having a non-intrusive novel positioning of the electrode system coupled with high speed data logger system. Objects of the invention Thus an object of the present invention is to provide a foam-measuring device for the continuous measurement of foam conductivity as a measure of foam stability. Yet another object of the present invention is to provide a foam-measuring device for the continuous measurement of foam conductivity, which has an electrode stack to negate the effects of foam creep thereby making the resistance measurements more accurate. Yet another object of the present invention is to provide a foam-measuring device for the continuous measurement of foam conductivity, which does not use cost-extensive gas-sparging systems for foam generation. A further object of the present invention is to provide a foam-measuring device for the continuous measurement of foam conductivity, which is provided with an automatic shaker for foam generation where the amplitude, frequency and time of shaking can be fixed to avoid individual variations. A further object of the present invention is to provide a foam-measuring device for the continuous measurement of foam conductivity, which is portable. Yet another object of the present invention is to provide a foam-measuring device for the continuous measurement of foam conductivity, which has a simple construction and is easy to handle. Yet another object of the present invention is to provide a foam-measuring device for the continuous measurement of foam conductivity that is economical and does not utilize complicated methods of analysis and has no requirement of specialized skills or facility. A further object of the present invention is to provide a foam-measuring device for the continuous measurement of foam conductivity that measures foam stability in terms of foam drainage by a non -destructive method. A further object of the present invention is to provide a foam-measuring device for the continuous measurement of foam conductivity that is used to gauge the quality of foam, suspension characteristics of foam ingredients together with the drainage characteristics as a function of time. Yet another object of the present invention is to provide a foam-measuring device for the continuous measurement of foam conductivity that may be used to provide a speedy quality control check and assessment on foam characteristics at various stages of formulations. Summary of the invention: Thus according to an aspect of the present invention there is provided a portable foam-measuring device for the continuous measurement of foam conductivity comprising - a foam cell - plurality of oppositely paired electrodes implanted across the length of the foam cell - an automated foam generating shaker adapted for the foam cell - a tunable current source and - a high-speed data logger system for data acquisition and processing. The details of the invention, its objects and advantages will now be explained hereunder in greater detail. Detailed description The portable device of the present invention can be effectively used for all applications and industries that require the monitoring of foam characteristics of products falling in several categories like personal wash, laundry products, food products like ice-creams, shampoos and so on. Foam is generated in the foam cell by shaking on the automatic shaker designed for the foam cell. The amplitude, frequency and time for shaking can be pre-fixed to avoid any individual discrepancies that arise in manual shaking. The quality of foam generated for a particular product is thus uniform and independent of the operator. A known current is passed through the foam cell containing the foam to be measured. The potential difference across the parallel plate electrodes is measured by a resistance meter calculating the resistance offered by the foam across the electrodes. The foam cell preferably has a square cross-section. It is desirable that the surface of the inside walls of the foam cell on which electrodes are not mounted is roughened. This may be provided by making striations on the surface. It is preferred that the striations have a depth of the order of 30 to 50 micrometers. Not wishing to be bound by theory, it is believed that the roughening ensures that the probability of forming a continuous soap film along the inner circumferential wall of the foam cell is minimal. Thus, the electrodes measure the resistance of the foam across the cross-section of the cell, as desired. Preferably the device comprises at least six pairs of oppositely placed electrodes. More preferably, the pairs of oppositely placed electrodes are uniformly spaced along the length of the foam cell. The high-speed on-line data logging systems assimilates readings across all the pairs of electrodes in fractions of a second. Hence statistically significant numbers of data points are obtained that enables accurate estimation of foam characteristics. Detailed description of drawings: The present invention will be described further in reference to non-limiting embodiments of the invention by way of accompanying figures wherein FIG. 1 is a perspective view of the foam cell of the portable foam-measuring device for the continuous measurement of foam conductivity in accordance to a preferred embodiment of the present invention. FIG. 2 is a top view of the foam cell of Fig. 1. FIG. 3 is a schematic view of the portable foam-measuring device for the continuous measurement of foam conductivity with the shaker. FIG. 4A and 4B depicts typical plots of the data collected by the data logger system with the resistance values in ohms plotted against time for the six channels (CH1 to CH6). Referring to the figures, Fig. 1 is a perspective view of the foam cell (FC) of the portable foam-measuring device for the continuous measurement of foam conductivity in accordance to a preferred embodiment of the present invention. The foam cell of this embodiment has a square cross section and has a plurality of oppositely paired electrodes (E1 and E2) across the length of the foam cell. The embodiment of Fig. 1 has six such pairs of electrodes. The surface of the inside walls of the foam cell not having the electrodes have striations (ST) as depicted in Fig. 2. A junction box (JB) contains the tunable current source and the data acquisition module to be connected to the data logger (not shown). The foam cell is shaken about its axis using a shaker (SH) as depicted in Fig. 3. The amplitude and frequency of shaking is controlled using a shaker controller (SC) whose settings can be preset by the user. The data is acquired by the data logger and processed into the form of graphs as shown in Fig. 4A and 4B. Thus the portable foam measuring device of the invention provides for a continuous measurement of foam conductivity and thereby its characteristics in a cost effective manner and without use of intrusive electrodes that affect the foam characteristics. We Claim 1. A portable foam-measuring device for the continuous measurement of foam conductivity comprising - a foam cell - plurality of oppositely paired electrodes implanted across the length of the foam cell - an automated foam generating shaker adapted for the foam cell - a tunable current source and - a high-speed data logger system for data acquisition and processing. 2. A portable foam measuring device as claimed in claim 1 wherein the surface of the inner walls of the foam cell on which electrodes are mounted is roughened. 3. A portable foam measuring device as claimed in claim 2 wherein the surface of the inner walls of the foam cell are roughened with striations which have a depth of the order of 30 to 50 micrometers. 4. A portable foam measuring device as claimed in any one of the preceding claims wherein the foam cell has a square cross-section. 5. A portable foam measuring device as claimed in any one of the preceding claims wherein the pairs of oppositely placed electrodes are uniformly spaced along the length of the foam cell. Dated this 7th day of December 2005 HINDUSTAN LEVER LIMITED S. Venkatramani Senior Patents Manager

Documents:

1340-mum-2004-abstract(24-05-2007).doc

1340-mum-2004-abstract(24-05-2007).pdf

1340-mum-2004-claims(granted)-(24-05-2007).doc

1340-mum-2004-claims(granted)-(24-05-2007).pdf

1340-mum-2004-correspondence(ipo)-(19-10-2007).pdf

1340-mum-2004-correspondence1(24-05-2006).pdf

1340-mum-2004-correspondence2(24-09-2007).pdf

1340-mum-2004-drawing(24-05-2007).pdf

1340-mum-2004-form 1(15-12-2004).pdf

1340-mum-2004-form 13(03-10-2007).pdf

1340-mum-2004-form 18(24-05-2006).pdf

1340-mum-2004-form 2(granted)-(24-05-2007).doc

1340-mum-2004-form 2(granted)-(24-05-2007).pdf

1340-mum-2004-form 3(07-12-2005).pdf

1340-mum-2004-form 3(15-12-2004).pdf

1340-mum-2004-form 5(07-12-2005).pdf

1340-mum-2004-power of attorney(18-05-2007).pdf