Systems for self-balancing control of mixing and pumping
First Claim
1. A control system for continuously mixing at least two materials, comprising:
- a mixing process;
wherein said process receives at least two input flow streams and has one output flow stream for the resulting mixture; and
a process control system acting on said mixing process wherein said control system is configured to;
(i) as a first priority, provide a desired density for said mixture; and
(ii) as a lower priority, provide a desired flow rate for said mixture.
1 Assignment
0 Petitions
Accused Products
Abstract
Systems for controlling the in-feed and discharge rates of materials flowing into and out of a mixing process where one priority is to achieve a target mixture flow rate from the mixing process and another priority can be to achieve a target value for a mixture property. Actuators can be operated to control material in-feed rates, the mixture composition, and discharge rate, and can maintain a hold-up of the mixture in the mixing process. A total flow rate controller provides a control signal to a controller acting on the discharge rate and a controller acting on the in-feed rates. The mixture discharge flow rate can be automatically reduced from its desired target when the commanded rate of at least one of the materials exceeds its available supply rate as inferred from an inability to maintain the targeted value for the mixture property.
-
Citations
26 Claims
-
1. A control system for continuously mixing at least two materials, comprising:
-
a mixing process;
wherein said process receives at least two input flow streams and has one output flow stream for the resulting mixture; anda process control system acting on said mixing process wherein said control system is configured to; (i) as a first priority, provide a desired density for said mixture; and (ii) as a lower priority, provide a desired flow rate for said mixture. - View Dependent Claims (2, 3)
-
-
4. A control system for continuously mixing at least two materials, comprising:
-
(a) a first control element and a second control element, each operable to control the flow rate of an individual material feeding into a mixing process; (b) a third control element, operable to control the discharge flow rate from said mixing process; and (c) a control system connected to said control elements, comprising; (i) a first control stage for controlling the respective flow rates of individual materials feeding into a mixing process, with respect to a desired value of a property of the resulting mixture; and (ii) a second control stage for controlling the discharge flow rate from said mixing process in dependence on the difference between a sensed value and an estimated value for said property;
whereby said difference can be due to a supply constraint of at least one of said individual materials;
wherein the error between said desired value and said sensed value is reduced when said supply constraint occurs. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. A control system for continuously mixing at least two materials, comprising:
-
(a) a first actuator and a second actuator, each operable to control the flow rate of an individual material feeding into a mixing process; (b) a third actuator, operable to control the discharge flow rate from said mixing process; and (c) a control system connected to said actuators; and
configured to provide;(i) control of the respective flow rates of individual materials feeding into said mixing process, with respect to a desired value of the density of the resulting slurry; (ii) an estimate of the expected density of the mixed materials;
wherein if the actual density of the mixed materials falls below the desired density, without corresponding change in any controlled variable, then said control system temporarily reduces the total flow rate through said process;
whereby errors due to supply constraints on the dry material are temporarily ameliorated by reduced total flow; and(iii) a temporary reduction of said total flow rate if actuator response to commanded increases in supply flow of a liquid material component of the slurry is inadequate;
whereby errors due to supply constraints on said liquid material are temporarily ameliorated by reduced total flow. - View Dependent Claims (15, 16, 17, 18)
-
-
19. A control system for continuously mixing at least two materials, comprising:
-
(a) actuators and/or control elements for controlling the respective flow rates of individual materials feeding into a mixing process, based on a desired density for the resulting mixture; (b) an actuator and/or a control element for controlling the discharge flow rate from said process, based on a master flow rate set point; and (c) a control system connected to said actuators and/or control elements for generating a master flow rate set point, based on; (i) the difference between a sensed value and an estimated value for said property;
wherein said difference can be due to a supply constraint of at least one of said individual materials; and(ii) a desired discharge flow rate for said process. - View Dependent Claims (20, 21, 22, 23, 24)
-
-
25. A control system for continuously mixing at least two materials, comprising:
-
means for controlling the flow rates of materials into a mixing process;
wherein said means provide control based on a desired density for the mixture resulting from said process;means for controlling the flow rate of the mixture discharging from said process;
wherein said means provide control based on a master flow rate set point;means for detecting a material supply constraint for said materials flowing into said process; and means for generating said master flow rate set point;
wherein said means generate said set point based on the occurrence of a said material supply constraint.
-
-
26. A control system for continuously mixing water and cement, comprising:
-
a cement mixing system, comprising; actuators which control the respective flow rates of water and cement into said mixing system with respect to a desired mixed cement density; and at least one pump for delivering the resulting wet mixed cement into a hydrocarbon well to thereby cement the casing to the well bore;
wherein the flow rate generated by said pump is based on a desired pumping rate; anda control system which controls said actuators and said pump;
wherein as a first priority, said control system operates to provide said desired density for said mixture.
-
Specification