Systems for volumetrically controlling a mixing apparatus

Abstract

Systems are provided for controlling a volumetric ratio of a material to total materials in a mixing vessel. In various embodiments, the systems may comprise: a volumetric ratio observer for estimating the volumetric ratio of the material to the total materials in the mixing vessel and an output flowrate of the material from the mixing vessel; a flow regulator coupled to the volumetric ratio observer for dynamically recomputing a commanded input flowrate of the material based on outputs of the volumetric ratio observer; and a flow modulator coupled to the flow regulator for adjusting an input valve of the material based on the commanded input flowrate of the material. In an embodiment, the mixing vessel comprises a first mixing vessel partially separated from a second mixing vessel. In this case, a height observer may be used to estimate a height of the total materials in the second mixing vessel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a mixing apparatus comprising two mixing vessels separated by a weir.

FIG. 2 is a state block diagram of an embodiment of a physical system and a flow modulator being used to volumetrically mix components in the mixing vessels shown in FIG. 1.

FIG. 3A is a state block diagram of an embodiment of a portion of a volumetric ratio observer for use with a single mixing vessel.

FIG. 3B is a state block diagram of another embodiment of a portion of a volumetric ratio observer for use with two mixing vessels.

FIG. 4 is a state block diagram of an embodiment of a control system for controlling the mixing apparatus depicted in FIG. 1.

FIG. 5 is a state block diagram of another embodiment of a control system for controlling the mixing apparatus depicted in FIG. 1.

FIG. 6 is a state block diagram of yet another embodiment of a control system for controlling the mixing apparatus depicted in FIG. 1.

FIG. 7 is a state block diagram of yet another embodiment of a portion of a volumetric ratio observer for use with mixing three components utilizing a two-vessel mixing apparatus.

FIG. 8 is a state block diagram of still another embodiment of a volumetric ratio observer for use with mixing three components utilizing a two-vessel mixing apparatus.

FIG. 9 shows how a process for mixing multiple components in a mixing apparatus comprising a single vessel or tank can be controlled using a volumetric ratio mixing control scheme.

FIG. 10 shows results obtained from systems according to FIGS. 2-9.

FIG. 11 shows yet another embodiment, with a different implementation of the disclosed volumetric control ideas.

Claims

1. A system for controlling a volumetric ratio of a material to total materials in a mixing vessel, comprising: a volumetric ratio observer for estimating the volumetric ratio of the material to the total materials in the mixing vessel and an output flowrate of the material from the mixing vessel;a flow regulator coupled to the volumetric ratio observer for dynamically recomputing a commanded input flowrate of the material based on outputs of the volumetric ratio observer; anda flow modulator coupled to the flow regulator for adjusting an input valve of the material based on the commanded input flowrate of the material.

2. The system of claim 1, wherein the mixing vessel comprises a first mixing vessel partially separated from a second mixing vessel

3. The system of claim 2, further comprising a height observer for estimating a height of the total materials in the second mixing vessel.

4. The system of claim 2, wherein the volumetric ratio observer is capable of estimating the volumetric ratio of the material to the total materials in the first mixing vessel and an output flowrate of the material from the first mixing vessel.

5. The system of claim 3, wherein: the height observer is also capable of estimating a total volumetric disturbance flowrate, the height observer having the following inputs: a measured height of the total materials in the second mixing vessel; a commanded input flowrate of the total materials; and a measured output flowrate of the total materials from the second mixing vessel;the volumetric ratio observer is also capable of estimating a volumetric disturbance flowrate of the material, the volumetric ratio observer having the following inputs: the estimated total volumetric disturbance flowrate determined by the height observer and a commanded input flowrate of the material; andthe flow regulator has the following inputs: the estimated volumetric ratio of the material to the total materials in the first mixing vessel; the estimated volumetric disturbance flowrate of the material; and the estimated output flowrate of the material from the first mixing vessel.

6. The system of claim 1, wherein the total materials comprise a fluid and a gas-transported dry material.

7. The system of claim 1, wherein the total materials comprise water and cement.

8. The system of claim 3, wherein the height observer comprises a PI controller.

9. The system of claim 8, wherein the height observer further comprises an Integral controller coupled to the PI controller.

10. The system of claim 1, wherein the volumetric ratio observer comprises first and second PI controllers.

11. The system of claim 3, further comprising a weir flow observer coupled to the flow regulator for estimating an output flowrate of the total materials from the first mixing vessel, the weir flow observer having the following inputs: the estimated height of the total materials in the second mixing vessel; the measured height of the total materials in the second mixing vessel; and the measured output flowrate of the total materials from the second mixing vessel.

12. The system of claim 11, wherein the weir flow observer comprises a PI controller.

13. The system of claim 12, wherein the weir flow observer further comprises an Integral controller coupled to the PI controller.

14. The system of claim 3, further comprising a state feedback controller for computing a commanded output flowrate of the total materials from the first mixing vessel, the state feedback controller having the following inputs: a commanded height of the total materials in the second mixing vessel; the estimated height of the total materials in the second mixing vessel; and the commanded output flowrate of the total materials from the second mixing vessel.

15. The system of claim 14, wherein the flow regulator comprises a second portion coupled to the state feedback controller for dynamically recomputing the commanded input flowrate of the total materials, the second portion having the following inputs: the commanded output flowrate of the total materials from the first mixing vessel; the estimated output flowrate of the total materials from the first mixing vessel; and the estimated total volumetric disturbance flowrate.

16. The system of claim 15, wherein the flow modulator is further capable of adjusting an input valve for a second material based on the commanded input flowrate of the total materials and the commanded input flowrate of the material.

17. A system for controlling a volumetric ratio of a material to total materials in a first mixing vessel that is partially separated from a second mixing vessel, comprising: a volumetric ratio observer for estimating the volumetric ratio of the material to the total materials in the second mixing vessel, an output flowrate of the material from the first mixing vessel, and a volumetric disturbance flowrate of the material, the volumetric ratio observer having the following inputs: an estimated total volumetric disturbance flowrate and a commanded input flowrate of the material;a state feedback controller for computing a commanded output flowrate of the material from the first mixing vessel, the state feedback controller having the following inputs: a commanded volumetric ratio of the material to the total materials in the second mixing vessel and the estimated volumetric ratio of the material to the total materials in the second mixing vessel;a flow regulator coupled to the state feedback controller and to the volumetric ratio observer for dynamically recomputing the commanded input flowrate of the material, the flow regulator having the following inputs: the estimated volumetric disturbance flowrate of the material and the estimated output flowrate of the material from the first mixing vessel; anda flow modulator coupled to the flow regulator for adjusting an input valve of the material based on the commanded input flowrate of the material.

18. The system of claim 17, the total materials comprise a fluid and a gas-transported dry material.

19. The system of claim 17, wherein the total materials comprise water and cement.

20-29. (canceled)

30. A system for controlling a volumetric ratio of a material to total materials in a first mixing vessel that is partially separated from a second mixing vessel, comprising: a volumetric ratio observer for estimating a total volumetric disturbance flowrate, the volumetric ratio of the material to the total materials in the first mixing vessel, and an output flowrate of the material from the first mixing vessel, the volumetric ratio observer having the following inputs: a measured height of the total materials in the second mixing vessel; an input flowrate of the material; and a commanded input flowrate of a second material that is also being fed to the first mixing vessel;a flow regulator coupled to the volumetric ratio observer for dynamically recomputing a commanded input flowrate of the material having the following inputs: a commanded volumetric ratio of the material to the total materials in the first mixing vessel; the estimated volumetric ratio of the material to the total materials in the first mixing vessel; and the estimated output flowrate of the material from the first mixing vessel; anda flow modulator coupled to the flow regulator for adjusting an input valve of the material based on the commanded input flowrate of the material.

31-45. (canceled)