OXYGEN TRIM CONTROLLER TUNING DURING COMBUSTION SYSTEM COMMISSIONING

• US 20110223548A1
• Filed: 11/25/2008
• Published: 09/15/2011
• Est. Priority Date: 11/25/2008
• Status: Active Grant

• Current Assignee: UTC Fire & Security Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: UTC Fire & Security Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Lelic, Muhidin A., Poncia, Guido, Fan, Junqiang
• Granted Patent: US 8,439,667 B2
• Time in Patent Office: Days
• US Class Current: 431/12
• CPC Class Codes: F23N 1/022 using electronic means
• CPC Class Codes: F23N 1/082 using electronic means
• CPC Class Codes: F23N 2223/42 Function generator
• CPC Class Codes: F23N 2223/44 Optimum control
• CPC Class Codes: F23N 2225/18 feedwater temperature
• CPC Class Codes: F23N 2227/20 Calibrating devices
• CPC Class Codes: F23N 2233/04 with variable speed
• CPC Class Codes: F23N 2235/06 at the air intake
• CPC Class Codes: F23N 2235/14 electromagnetically operated
• CPC Class Codes: F23N 2241/04 Heating water
• CPC Class Codes: F23N 2241/10 Generating vapour
• CPC Class Codes: F23N 5/006 the detector being sensitive to oxygen

Abstract

A method is provided for tuning an oxygen trim controller during the commissioning of a combustion control system for controlling operation of a boiler combustion system, rather than tuning the oxygen trim controller after the commissioning process has been completed.

Claims

1. A method of tuning an oxygen trim controller during a commissioning process of a combustion control system for controlling operation of a boiler combustion system having a fuel flow control device operatively associated with a burner and an air flow control device operatively associated with the burner and discharging a flue gas, the method comprising the steps of:

(a) at a first selected firing rate selecting one of either the servo position of the fuel flow control device or the servo position of the air flow control associated with the selected firing rate point;

(b) defining an excess oxygen content target value for the selected firing rate point;

(c) varying the servo position of the other of the air flow control device or the fuel flow control device until a measured steady-state value of the excess oxygen content in the flue gas falls within a predefined range of a preselected excess oxygen target value associated with the first selected firing rate, thereby establishing a first coordinated set of a first air servo position and a first fuel servo position;

(d) measuring the excess oxygen content in the flue gas while varying the servo position is during step (c);

(e) establishing a transfer function model for the relationship between excess oxygen content and the first selected firing rate based on the measured excess oxygen contents and the corresponding servo positions from step (d);

(f) repeating steps (a) through (e) for a plurality of selected firing rates; and

(g) saving the transfer function models associated with each respective firing rate of the plurality of selected firing rates;

(h) calculating and saving the controller parameters of the oxygen trim controller based on the transfer function models from step (g).

2. The method of tuning an oxygen trim controller as recited in claim 1 further comprising the step of determining an average transfer function model over at least two of the plurality of the selected firing rates representative of the plurality of transfer function models associated with the at least two of the plurality of the selected firing rates.

3. The method of tuning an oxygen trim controller as recited in claim 2 further comprising the step of:

using the average transfer function model to calculate a proportional parameter gain factor for the oxygen trim controller.

4. The method of tuning an oxygen trim controller as recited in claim 2 further comprising the step of:

using the average transfer function model to calculate an integral parameter gain factor for the oxygen trim controller.

5. The method of tuning an oxygen trim controller as recited in claim 1 further comprising the step of calculating at each firing rate, a set of the controller parameters associated with said firing rate based on the transfer function model obtained at said firing rate from step (g).