Feedback control for reducing flaring process smoke and noise
A method of reducing plant emissions includes providing a MPC model for a flaring process including one-to-one models between controlled variables (CVs) including a smoke count and/or a flare count (CV 1 ) and a noise level (CV 2 ), and flow of assist gas as a manipulated variable (MV) and another process gas flow as a disturbance variable (DV). The MPC model receives sensed flare-related parameters during the flaring process including a measure of CV 1 (CV 1 *) and CV 2 (CV 2 *). Provided CV 1 * is above a minimum setpoint for CV 1 (CV 1 setpoint) and CV 2 * is above a setpoint for CV 2 (CV 2 setpoint), the flaring process is automatically controlled using the MPC model which determines an updated flow setpoint for MV from CV 1 * and CV 2 *, the CV 1 and CV 2 error, and the identified one-to-one models.
1. A method of reducing emissions at a processing plant, comprising:
providing a model predictive control (MPC) model for a flaring process run at said processing plant including an assist gas comprising a plurality of identified one-to-one models between controlled variables (CVs) including (i) at least one of a smoke count and a flare count (CV 1 ) and (ii) a noise level (CV 2 ), and a flow of said assist gas as a manipulated variable (MV) and at least one other process gas flow as a disturbance variable (DV);
said MPC model implemented by a processor receiving sensed flare-related parameters during operation of said flaring process including a measure of said CV 1 (CV 1 *) and said CV 2 (CV 2 *), and
provided said CV 1 * is above a predetermined minimum setpoint for said CV 1 (CV 1 setpoint) and said CV 2 * is above a predetermined setpoint for said CV 2 (CV 2 setpoint), automatically controlling said flaring process using said MPC model implemented by said processor which automatically determines an updated flow setpoint for said MV based on (i) said CV 1 * and said CV 2 *, (ii) a difference between said CV 1 setpoint and said CV 1 * and a difference between said CV 2 setpoint and said CV 2 *, and (iii) said identified one-to-one models.
2. The method of claim 1 , wherein said DV is a sensed to provide a measure of said DV (DV*) or said DV is estimated, and wherein said identified one-to-one models include said DV.
3. The method of claim 1 , wherein said identified one-to-one models do not include said DV, and wherein said MPC model treats an effect of said DV on said MV as a plant-model mismatch.
4. The method of claim 1 , wherein said CV 1 includes said smoke count.
5. The method of claim 1 , wherein said assist gas comprises steam, a combustible gas, or air.
6. The method of claim 5 , wherein said assist gas comprises said steam.
7. The method of claim 1 , wherein said CV 1 setpoint and said CV 2 setpoint are both determined by a ground truth benchmarking process.
8. The method of claim 1 , further comprising implementing said updated flow setpoint for said MV using a process controller coupled to receive said updated flow setpoint for said MV which is coupled to an actuator that controls a valve position to provide said updated flow setpoint for said MV.
9. A method of reducing emissions at a processing plant, comprising:
providing a model predictive control (MPC) model for a flaring process run at said processing plant including steam as an assist gas comprising a plurality of identified one-to-one models between controlled variables (CVs) including (i) a smoke count (CV 1 ) and (ii) a noise level (CV 2 ), and a flow of said steam as a manipulated variable (MV) and at least one other process gas flow as a disturbance variable (DV);
said MPC model implemented by a processor receiving sensed flare-related parameters during operation of said flaring process including a measure of said CV 1 (CV 1 *) and said CV 2 (CV 2 *), and
provided said CV 1 * is above a predetermined minimum setpoint for said CV 1 (CV 1 setpoint) and said CV 2 * is above a predetermined setpoint for said CV 2 (CV 2 setpoint), automatically controlling said flaring process using said MPC model implemented by said processor which automatically determines an updated flow setpoint for said MV based on (i) said CV 1 * and said CV 2 *, (ii) a difference between said CV 1 setpoint and said CV 1 * and a difference between said CV 2 setpoint and said CV 2 *, and (iii) said identified one-to-one models.
10. A system for reducing emissions at a processing plant, comprising:
a plurality of sensors for sensing flare-related parameters including a sensor for sensing at least one of a smoke count and a flare count and a sensor for sensing a noise level emitted from a flare stack during operation of a flaring process at said processing plant;
a model predictive control (MPC) model for controlling said flaring process including an assist gas comprising a plurality of identified one-to-one models between controlled variables (CVs) including (i) at least one of said smoke count and said flare count (CV 1 ) and (ii) said noise level (CV 2 ), and a flow of said assist gas as a manipulated variable (MV) and at least one other process gas flow as a disturbance variable (DV);
a control system including a processor receiving said flare-related parameters from said plurality of sensors during operation of said flaring process including a measure of said CV 1 (CV 1 *) and said CV 2 (CV 2 *), said processor implementing said MPC model;
wherein provided said CV 1 * is above a predetermined minimum setpoint for said CV 1 (CV 1 setpoint) and said CV 2 * is above a predetermined setpoint for said CV 2 (CV 2 setpoint), automatically controlling said flaring process using said MPC model implemented by said processor which automatically determines an updated flow setpoint for said MV based on (i) said CV 1 * and said CV 2 *, (ii) a difference between said CV 1 setpoint and said CV 1 * and a difference between said CV 2 setpoint and said CV 2 *, and (iii) said identified one-to-one models, and
a process controller coupled to receive said updated flow setpoint for said MV from said control system which is coupled to an actuator that controls a valve position to provide said updated flow setpoint for said MV that implements said updated flow setpoint for said MV.
11. The system of claim 10 , further comprising a flow sensor for sensing said DV to provide a measure of said DV (DV*) or said DV is estimated, and wherein said identified one-to-one models include said DV.
12. The system of claim 10 , wherein said identified one-to-one models do not include said DV, and wherein said MPC model treats an effect of said DV on said MV as a plant-model mismatch.
13. The system of claim 10 , wherein said sensor for sensing at least one of said smoke count and said flare count includes a smoke count sensor.
14. The system of claim 10 , wherein said assist gas comprises steam, a combustible gas, or air.
15. The system of claim 14 , wherein said assist gas comprises said steam.
16. A computer program product, comprising:
a non-transitory data storage medium that includes program instructions executable by a processor to enable said processor to execute a method of reducing emissions at a processing plant, said program instructions including:
code for said processor implementing a model predictive control (MPC) model for a flaring process run at said processing plant including an assist gas comprising a plurality of identified one-to-one models between controlled variables (CVs) including (i) at least one of a smoke count and a flare count (CV 1 ) and (ii) a noise level (CV 2 ), and a flow of said assist gas as a manipulated variable (MV) and at least one other process gas flow as a disturbance variable (DV); wherein said processor receives sensed flare-related parameters during operation of said flaring process including a measure of said CV 1 (CV 1 *) and said CV 2 (CV 2 *), and
code for checking that said CV 1 * is above a predetermined minimum setpoint for said CV 1 (CV 1 setpoint) and said CV 2 * is above a predetermined setpoint for said CV 2 (CV 2 setpoint), and
code for automatically controlling said flaring process using said MPC model provided said CV 1 * is above said CV 1 setpoint and said CV 2 * is above said CV 2 setpoint based on i) said CV 1 * and said CV 2 *, (ii) a difference between said CV 1 setpoint and said CV 1 * and a difference between said CV 2 setpoint and said CV 2 *, and (iii) said identified one-to-one models.
17. The computer program product of claim 16 , wherein said DV is a sensed to provide a measure of said DV (DV*) or said DV is estimated, and wherein said identified one-to-one models include said DV.
18. The computer program product of claim 16 , wherein said identified one-to-one models do not include said DV, and wherein said MPC model treats an effect of said DV on said MV as a plant-model mismatch.
19. The computer program product of claim 16 , wherein said CV 1 includes said smoke count.
20. The computer program product of claim 16 , wherein said assist gas comprises steam.