Method and device for the consideration of varying volume and flow in the control of a continuous flow process
First Claim
1. A method for incorporation of varying volume and flow in the control of other process variables in a continuous flow process, comprising the steps of:
- measuring and storing at least two of the process variables of inlet flow (Qin), outlet flow (Q) and volume (V);
determining a new variable (z) at time (t) wherein said new variable (z) is dependent on said at least two process variables;
determining an output quantity (u(t)) of a controller at the same time (t) based on the new variable (z) by using a method which is invariant with respect to the new variable (z); and
controlling one or more of said other process variables by applying a signal representative of the determined output quantity (u(t)) to a means for controlling said other process variables.
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Abstract
The control method is directed to a quality characteristic of the process material, typically to its outlet concentration. In control of the actuator which is a part of feedforward or feedback control of outlet concentration, one takes account of changes of the material volume and flow, in addition to the inlet concentration or control deviation. With this object, at least two of the quantities of inlet flow, outlet flow and material volume are measured or determined and by means of them a variable is further determined with regard to which the control method is invariant. Two alternative variables are presented, one being typically applicable to control of a process with finite distribution of the flow velocity and the other to control of a process with vigorous mixing. By means of a time-variable control method, the controls can also be implemented with time as the independent variable. The invention also relates to devices which implement the control methods presented.
49 Citations
14 Claims
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1. A method for incorporation of varying volume and flow in the control of other process variables in a continuous flow process, comprising the steps of:
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measuring and storing at least two of the process variables of inlet flow (Qin), outlet flow (Q) and volume (V); determining a new variable (z) at time (t) wherein said new variable (z) is dependent on said at least two process variables; determining an output quantity (u(t)) of a controller at the same time (t) based on the new variable (z) by using a method which is invariant with respect to the new variable (z); and controlling one or more of said other process variables by applying a signal representative of the determined output quantity (u(t)) to a means for controlling said other process variables. - View Dependent Claims (2, 3, 4, 5)
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6. A method for incorporation of varying mass and flow in the control of other process variables in a continuous flow process in a gas vessel of constant volume comprising the steps of:
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measuring and storing at least two of the process variables of inlet flow, outlet flow and mass or pressure, determining a new variable by integrating the inlet flow with respect to time up to a time (t) and then dividing the integrated value by a quantity that is proportional to the mass at the same time (t); determining an output quantity of a controller at the same time (t) based on the new variable and using a method which is invariant with respct to the new variable; and controlling one or more of said other process variables by applying a signal representative of the determined output quantity to a means for controlling said other process variables. - View Dependent Claims (7)
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8. A method for incorporation of varying mass and flow in the control of other process variables in a continuous flow process in a gas vessel of constant volume comprising the steps of:
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measuring and storing at least two of the process variables of inlet flow, outlet flow and mass or pressure, determining a new variable by dividing the inlet flow by a quantity which is proportional to the mass and integrating the quotient with respect to time up to a time (t); determining an output quantity of a controller at the same time (t) based on the new variable and using a method which is invariant with respect to the new variable; and controlling one or more of said other process variables by applying a signal representative of the determined output quantity to a means for controlling said other process variables. - View Dependent Claims (9)
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10. An apparatus for incorporation of varying volume and flow in the control of other process variables in a continuous flow process, comprising:
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means for measuring and storing at least two of the process variables of inlet flow (Qin), outlet flow (Q) and volume (V); means for determining a new variable (z) at time (t) wherein said new variable (z) is dependent on said at least two process variables; means for determining an output quantity (u(t)) of a controller at the same time (t) based on the new variable (z) by using a method which is invariant with respect to the new variable (z); and means for controlling said other process variables based on the determined output quantity (u(t)). - View Dependent Claims (11, 12)
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13. An apparatus for incorporation of varying mass and flow in the control of other process variables in a continuous flow process in a gas vessel of constant volume, comprising:
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means for measuring and storing at least two of the process variables of inlet flow, outlet flow and mass or pressure; means for determining a new variable by integrating the inlet flow with respect to time up to a time (t) and then dividing the integrated value by a quantity that is proportional to the mass at the same time (t); means for determining an output quantity of a controller at the same time (t) based on the new variable by using a method which is invariant with respect to the new variable; and means for controlling said other process variables based on the determined output quantity.
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14. An apparatus for incorporation of varying mass and flow in the control of other process variables in a continuous flow process in a gas vessel of constant volume, comprising:
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means for measuring and storing at least two of the process variables of inlet flow, outlet flow and mass or pressure; means for determining a new variable by dividing the inlet flow by a quantity which is proportional to the mass and integrating the quotient with respect to time up to a time (t); means for determining an output quantity of a controller at the same time (t) based on the new variable by using a method which is invariant with respect to the new variable; and means for controlling said other process variables based on the determined output quantity.
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Specification