METHOD FOR MEASURING DENSITY AND VISCOSITY OF PARTICLE-CONTAINING SOLUTION

Abstract: The invention relates to a method for measuring the properties of a solution, and in particular for measuring the solids content, viscosity and air content in solutions which contain solid particles, in which the solution to be measured is lead to the space (3) inside the measuring mechanism (2), the pressure inside which is regulated by a pressure control device (4), and inside which the density of the substance in the solution is measured with a densimeter (1), at which point the prevailing pressure is altered with a pressure control device (4) within the space (3) and the density of the solution is measured again, at least one more time, whereupon the solution's solids content is calculated from the density measurement and the air content is calculated at least from the two different density readings. In a method in accordance with the invention, the measuring mechanism (2) is connected to a cycle or corresponding system, with an interface (6), and the solution being processed in the cycle is lead to the measuring mechanism (2) and the solids content and air content of the solution are measured at the desired intervals, and the solution is lead from the measuring device through the capillary (7) or slit pipe back into the processing cycle, the difference between the current and pressure is measured both within the space of the measuring mechanism (3) and after the capillary/slit pipe, and the solution's viscosity is calculated from these two measurements.

Description: 1 Method for measuring density and viscosity of particle- containing solution The present invention relates to a method for measuring the properties of a solution, and in particular, the solids content in a solution which contains solid particles, and for measuring viscosity and air content. In the method of the present invention, the solution to be measured is lead into the space of the measuring mechanism, in which the pressure is regulated by a pressure control device, the density of the solution substance is measured with a densimeter, the predominant pressure is altered within the space using the pressure control device and the solution's density is measured again, at least one more time, whereupon the solids content in the solution is calculated from the densimeter and the air content is calculated from at least two different density evaluations. The precise determination of the solids content in solutions containing solid particles, such as mineral sludge, pastes and other corresponding solutions, is an important factor in determining the properties of the solution, how the solution should be treated, and/or different processes in which it is used. The solids content is generally measured with a conventional radiation-based densimeter. The results of the measurements are, however, imprecise because the air content in the solution varies due to the passage of time and different occurrences. At present, sufficient consideration is not given to these alterations in air content while measurements are being taken. US patents 4201082 and 4584866 present air content evaluation from two measurements taken under different pressures with a densimeter. The publication does not present a method for measuring the solution's different properties simply and quickly during the different cycle phases. The present invention seeks to provide a method by which both the solids content of a solution containing solid particles and the air content in the same solution can be measured, and by using this method, the invention seeks to eliminate the disadvantages associated with the present method. In particular, the invention seeks to provide a method, which is to be used for supervising the cycle, which, when used, yields property measurements for the processed solution simply and reliably, and which can be adapted to different purposes. The object of the invention is accomplished by means of a method, the characteristics of which are presented in the claims. A measuring mechanism in accordance with a method carried out in accordance with the invention is linked to the cycle or corresponding system, with an interface. The solution going through the cycle is lead to the measuring mechanism and the solids content and air content of the solution is measured at the desired intervals. The solution is lead from the measuring mechanism through the capillary or slit pipe back to the cycle. The difference in flow and pressure is measured within the measuring mechanism and also after the capillary/slit pipe, and then the viscosity of the solution is calculated/determined. Thus, the properties and alterations in the properties of the solution which is going through the cycle can be continuously followed, or followed at certain intervals. A method in accordance with the invention yields reliable and precise measurements of the solids content in a solution containing particles, and of the solution's viscosity and air content as it is going through a cycle or corresponding system. The method is suitable for measuring the solids content and air content of all sorts of solutions containing solid particles. The method is especially suited for use in measuring the properties of mineral sludge and pastes, such as coating slip. The method can be adapted for use in both industrial cycles and laboratories. In one advantageous application of the invention, a mechanism is connected to the sample tank with an interface and the solution inside the tank is lead to the measuring mechanism where the solids content, viscosity and air content of the solution is measured. In this case, the embodiment is intended for use in a laboratory and functions reliably for that purpose. The invention will now be described in more detail with reference to the accompanying drawing which diagrammatically illustrates a certain mechanism to which a method in accordance with the invention has been applied. A measuring mechanism formed in accordance with the figure 2 comprises a pressure control device 4, the space within the measuring mechanism 3 or tank, a densimeter 1 and an interface 6. The conventional densimeter 1 , located in or near the space 3, is comprised of a radioactive source in one half of the space and a detector in the other half. Additionally, a pressure sensor 8 is located in the space 3 in order to measure the predominant pressure. Further, a capillary 7 or slit pipe is incorporated into the space. In this embodiment, the space is formed as a pipe and the pipe is shaped as a letter "s", whereupon the range of the detector and source of radiation can always be adjusted to the optimum setting to obtain a case-specific sample. When using a measuring mechanism formed in accordance with the figure, the mechanism is connected, for example, to the sludge cycle or paper machine paste cycle. The substance is lead through the interface 6 to the pressure control device 4 and from there to the space or pipe 3. This pipe functions as a solids content and air content unit. When the tank/pipe 3 is pumped full in order to measure the paste/sludge solution and the pressure is, for example, 1 bar, the density of the sample is measured with the densimeter 1. Next, the pressure inside the solids and air content unit is raised to the desired value, for example, 50 bars, with the help of the pressure set by the pressure input unit and the same density measurement is taken again. In 50 bars of pressure, the air is pressed to one fiftieth of its former volume and the solids content can be calculated directly from the density. Air content is easily and reliably calculated from these two density measurements. If desired, other measurements can also be taken at other pressures, and the quantity of measurements taken and/or the pressures at which they are taken vary depending on the different embodiments of the invention. When measurements are taken at two or more different pressures, the air content of the solution can surely and reliably be determined and thus taken into consideration. Thus, the effect of the air is minimized in the results of the measurements. After being measured, the solution or corresponding substance can be pressed through the capillary 7 or slit pipe back into the cycle. When the solution is lead from the measuring mechanism through the capillary back into the cycle, it does not need to be lead elsewhere first or treated separately. The invention is not limited to the advantageous embodiment set forth in this patent application. The invention is versatile and its form can vary within the frame of the idea of the invention put forth in the claims.

Claims: CLAIMS 1. A method for measuring the properties of a solution, and in particular for measuring the solids content, viscosity and air content in solutions which contain solid particles, in which the solution to be measured is lead to the space (3) inside the measuring mechanism (2), the pressure inside which is regulated by a pressure control device (4), and inside which the density of the substance in the solution is measured with a densimeter (1 ), at which point the prevailing pressure is altered with a pressure control device (4) within the space (3) and the density of the solution is measured again, at least one more time, whereupon the solution's solids content is calculated from the density measurement and the air content is calculated at least from the two different density readings, characterized in that the measuring mechanism (2) is connected to a cycle or corresponding system, with an interface (6), and the solution being processed in the cycle is lead to the measuring mechanism (2) and the solids content and air content of the solution are measured at the desired intervals, and in that the solution is lead from the measuring device through the capillary (7) or slit pipe back into the processing cycle, the difference between the current and pressure is measured both within the space of the measuring mechanism (3) and after the capillary/slit pipe, and the solution's viscosity is calculated from these two measurements. 2. A method according to claim 1 , characterized in that a mechanism is connected to a sample tank by an interface and the solution in the sample tank is lead to the measuring mechanism where the solids content, viscosity and air content of the solution is measured.

Inventors: MUSTALAHTI HEIKKI, MUSTALAHTI, HEIKKI
Applicants: ACA SYSTEMS OY, MUSTALAHTI HEIKKI, MUSTALAHTI, HEIKKI
Application year: 1999
Main classification: G01N11
IPC codes: G01N9, G01N11