Mixer

Abstract

A mixer and a method for the mixing of a cementitious slurry, configured to calculate the volume of the cementitious slurry in the mixer in order to produce an improved mixing process and/or an improved cementitious product. The mixer comprises a sensor to measure a parameter of the slurry in the mixer that is used to calculate the volume of slurry in the mixer.

Claims

1-12. (canceled)

13. A mixer for the mixing of a cementitious slurry, the mixer comprising: an inlet for receiving a cementitious material and water; a mixing member configured to mix the cementitious material and water to form a cementitious slurry; an outlet for dispensing the cementitious slurry; a sensor configured to measure a parameter of the cementitious slurry; and a processor configured to use the parameter measurement to calculate a volume of the cementitious slurry in the mixer; wherein the sensor comprises an array of thermocouples; or the sensor comprises an infrared camera, and the mixer comprises an IR window configured to allow the transmission of infrared radiation from the cementitious slurry inside the mixer to the IR camera outside.

14. The mixer of claim 13, wherein the sensor comprises the array of thermocouples.

15. The mixer of claim 13, wherein the sensor comprises the infrared camera and the mixer comprises the IR window configured to allow the transmission of infrared radiation from the cementitious slurry inside the mixer to the IR camera outside

16. The mixer of claim 13, wherein the processor is further configured to calculate a slurry volume fraction of the mixer wherein the slurry volume fraction is defined according to the following formula: $\mathrm{Slurry}\mathrm{volume}\mathrm{fraction}=\frac{V\mathrm{olume}\mathrm{of}\mathrm{slurry}\mathrm{in}\mathrm{the}\mathrm{mixer}}{\mathrm{Total}\mathrm{volume}\mathrm{of}\mathrm{the}\mathrm{mixer}}$

17. The mixer of claim 13, wherein the processor is further configured to change at least one of an input parameter, a process parameter, and an output parameter of the mixer in response to the calculated volume of cementitious slurry in the mixer and/or the slurry volume fraction of the mixer.

18. The mixer of claim 13, wherein the input parameter is selected from the list consisting of: a line speed, an input speed, an input volumetric flow rate, an input temperature or the composition of the slurry.

19. The mixer of claim 13, wherein the process parameter is a mixing speed or a mixing temperature.

20. The mixer of claim 13, wherein the output parameter is selected from the list consisting of: a mixer output speed, an output volume, an output temperature or an outlet cross-section.

21. A process for the manufacture of a cementitious board, the process comprising: forming a slurry of water and cementitious material; mixing the slurry in a mixer; measuring a parameter of the slurry in the mixer using a sensor and calculating a volume of the slurry in the mixer using the measured parameter; depositing the slurry to form a board precursor; and drying the board precursor to form a cementitious board; wherein the sensor comprises an array of thermocouples; or the sensor comprises an infrared camera, and the mixer comprises an IR window configured to allow the transmission of infrared radiation from the cementitious slurry inside the mixer to the IR camera outside.

22. The process of claim 21, wherein the sensor comprises the array of thermocouples.

23. The process of claim 21, wherein the sensor comprises the infrared camera, and the mixer comprises the IR window configured to allow the transmission of infrared radiation from the cementitious slurry inside the mixer to the IR camera outside

24. The process of claim 21, wherein the process further comprises calculating a slurry volume fraction from the slurry volume, wherein the slurry volume fraction is defined according to the following formula: $\mathrm{Slurry}\mathrm{volume}\mathrm{fraction}=\frac{V\mathrm{olume}\mathrm{of}\mathrm{slurry}\mathrm{in}\mathrm{the}\mathrm{mixer}}{\mathrm{Total}\mathrm{volume}\mathrm{of}\mathrm{the}\mathrm{mixer}}$

25. The process of claim 21, wherein the process further comprises changing at least one of an input parameter, a process parameter, and an output parameter in response to the calculated volume and/or slurry volume fraction.

26. The process of claim 21, wherein the measurement of the parameter of the slurry is substantially continuous.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The disclosure will be further described with reference to examples depicted in the accompanying figures in which:

[0030] FIG. 1 is a diagram of an infrared camera system of an embodiment of a mixer of the present invention;

[0031] FIG. 2 is a diagram of an infrared camera system of an embodiment of a mixer of the present invention; and

[0032] FIG. 3 is an image taken by an IR camera in an embodiment of the present invention; and

[0033] FIG. 4 is a graph showing the relationship between the position of the slurry and time as measured by an IR camera of an embodiment of the present invention.

DETAILED DESCRIPTION

[0034] The following description presents particular examples and, together with the drawings, serves to explain principles of the disclosure. However, the scope of the invention is not intended to be limited to the precise details of the examples, since variations will be apparent to a skilled person and are deemed to be covered by the description. Terms for components used herein should be given a broad interpretation that also encompasses equivalent functions and features. In some cases, alternative terms for structural features may be provided but such terms are not intended to be exhaustive.

[0035] Descriptive terms should also be given the broadest possible interpretation; e.g. the term comprising as used in this specification means consisting at least in part of such that interpreting each statement in this specification that includes the term comprising, features other than that or those prefaced by the term may also be present. Related terms such as comprise and comprises are to be interpreted in the same manner. Directional terms such as vertical, horizontal, up, down, top, bottom, upper and lower are used for convenience of explanation usually with reference to the illustrations and are not intended to be ultimately limiting if an equivalent function can be achieved with an alternative dimension, orientation and/or direction.

[0036] The description herein refers to examples with particular combinations of features, however, it is envisaged that further combinations and cross-combinations of compatible features between embodiments will be possible. Indeed, isolated features may function independently as an invention from other features and not necessarily require implementation as a complete combination.

[0037] In an embodiment of the invention, a mixer comprises an IR camera mounted on a camera holder attached to the mixer. The mixer comprises a lid, a base and at least one side wall connecting the lid and the base. The mixer further comprises a IR window on the lid of the mixer. The IR window is configured to allow the transmission of infrared radiation from the slurry inside the mixer to the IR camera outside. The IR window comprises zinc sulphide and has a thickness of 5 mm. The camera holder is movable to allow the user to position the IR camera to optimise the field of view through the IR window. The IR window is located 4 cm from the side of the internal casing wall of the mixer.

[0038] Cementitious material, water, additives and other materials are added into the mixer to form a slurry. The cementitious material is hot when added and the hydration of the cementitious material is exothermic. Accordingly, the volume of slurry in the mixer can be determined using IR imaging due to the higher temperature of the slurry. As the slurry is mixed in the mixer, the slurry is pushed to the edges of the mixer due to the centrifugal force. The slurry forms a donut shape and the thickness of the donut shape can be characterised with IR imaging. To observe the slope of the donut, the IR window requires a field of view of at least 10 cm. The IR camera is positioned at an angle such there is an angle, , between the field of view of the camera, , and the perpendicular height of the camera, , to avoid reflection of the camera in the IR window. The distance between the 10 cm view and the base of the camera holder is defined as . The field of view of the camera, , is determined using the following formula:

[00003]$=\mathrm{arc}\tan \left(\frac{+10}{}\right)-\mathrm{arc}\tan \left(\frac{}{}\right)$

[0039] The orientation of the camera, , is determined using the following formula:

[00004]$=+\frac{}{2}=\mathrm{arc}\tan \left(\frac{+10}{}\right)+\frac{1}{2}\mathrm{arc}\tan \left(\frac{}{}\right)$

[0040] The IR images may be analysed to determine the position of the decreasing profile of the slurry and then the volume of slurry in the mixer.

[0041] As an alternative to in IR camera and window, the mixer comprises thermocouples and holes to accommodate the thermocouples in order to capture the heat profile of the slurry.

[0042] FIG. 1 is a schematic diagram of an IR system of an embodiment of the present invention. FIG. 1 illustrates the field of view of the IR camera 101 through the IR window 102 to the slurry 103 in the mixer 100.

[0043] FIG. 2 is a schematic diagram of an IR system of an embodiment of the present invention. The IR camera 101 receives infrared radiation through the IR window 102 from the cementitious slurry 103. The IR window 102 is located 4 cm from the inner side wall 104 of the mixer 100. The IR camera 101 is mounted on a camera holder 105 attached to the mixer 100.

[0044] FIG. 4 illustrates the relationship between the slurry position and time as measured by the IR camera. The observed variations are linked to changes in the slurry volume fraction of the mixer.