Automatic draft control system for coke plants
A coke oven includes an oven chamber, an uptake duct in fluid communication with the oven chamber, the uptake duct being configured to receive exhaust gases from the oven chamber, an uptake damper in fluid communication with the uptake duct, the uptake damper being positioned at any one of multiple positions, the uptake damper configured to control an oven draft, an actuator configured to alter the position of the uptake damper between the positions in response to a position instruction, a sensor configured to detect an operating condition of the coke oven, wherein the sensor includes one of a draft sensor, a temperature sensor configured to detect an uptake duct temperature or a sole flue temperature, and an oxygen sensor, and a controller being configured to provide the position instruction to the actuator in response to the operating condition detected by the sensor.
1. A coke oven, comprising:
an oven chamber;
an uptake duct in fluid communication with the oven chamber, the uptake duct being configured to receive exhaust gases from the oven chamber;
an uptake damper in fluid communication with the uptake duct, the uptake damper being positioned at any one of a plurality of positions including fully opened and fully closed, the uptake damper configured to control an oven draft;
an actuator configured to alter the position of the uptake damper between the plurality of positions in response to a position instruction;
a plurality of coke oven sensors each configured to detect an operating condition of the coke oven, wherein the plurality of sensors comprises a draft sensor configured to detect the oven draft, a temperature sensor configured to detect an uptake duct temperature or a sole flue temperature, and an oxygen sensor configured to detect an uptake duct oxygen concentration in the uptake duct; and
a controller in communication with the actuator and with the plurality of sensors, such that the controller receives a signal from each of the plurality of sensors that corresponds to a measured process value of the coke oven, the controller being configured to: (i) provide the position instruction to the actuator using inferential control that is based on anticipated changes in operating conditions of the coke oven, using multiple readings detected by the plurality of sensors over a period of time, rather than reacting to an individual detected operating condition detected by one of the plurality of sensors; (ii) provide the position instruction to the actuator to cause the actuator to alter the position of the uptake damper to thereby maintain the oven draft at or above a target oven draft pre-calculated for the coke oven under a normal steady-state for the coke oven without consideration of momentary fluctuations in the operating condition detected by each of the plurality of sensors; and (iii) provide the position instruction to the actuator to cause the actuator to alter the position of the uptake damper to thereby vary the targeted oven draft over a duration of a coking cycle.
2. The coke oven of claim 1 , wherein at least one of the plurality of coke oven sensors is positioned in the oven chamber.
3. The coke oven of claim 1 , wherein the controller is configured to provide the position instruction to the actuator to cause the actuator to alter the position of the uptake damper to thereby maintain the oven draft at least at 0.1 inches of water.
4. The coke oven of claim 1 , wherein the temperature sensor is positioned in the uptake duct.
5. The coke oven of claim 1 , wherein the controller is configured to provide the position instruction to the actuator to cause the actuator to alter the position of the uptake damper to thereby allow excess air into the oven in response to an overheat condition detected by the temperature sensor.
6. The coke oven of claim 1 , wherein the oxygen sensor is positioned in the uptake duct.
7. The coke oven of claim 1 , wherein the controller is configured to provide the position instruction to the actuator to cause the actuator to alter the position of the uptake damper to thereby maintain the uptake duct oxygen concentration within an oxygen concentration range.
8. The coke oven of claim 1 , wherein at least one of the plurality of coke oven sensors is positioned in the sole flue.
9. The coke oven of claim 8 , wherein the controller is configured to provide the position instruction to the actuator to cause the actuator to alter the position of the uptake damper to thereby allow excess air into the oven in response to an overheat condition detected by the temperature sensor.
10. The coke oven of claim 1 , wherein the controller is further operative to time-average differences in operating conditions detected by the plurality of sensors.
11. The coke oven of claim 10 , wherein position instructions provided by the controller are linearly proportional to the differences in the time-averaged operating conditions detected by the plurality of sensors.
12. The coke oven of claim 10 , wherein position instructions provided by the controller are non-linearly proportional to the differences in the time-averaged operating conditions detected by the plurality of sensors.
13. The coke oven of claim 1 , wherein the controller is further operative to maintain a constant time-averaged oven draft within a predefined tolerance of the target oven draft throughout the coking cycle.
14. The coke oven of claim 13 , wherein the tolerance of the target oven draft is plus or minus 0.5 inches of water.
15. The coke oven of claim 13 , wherein the tolerance of the target oven draft is plus or minus 0.02 inches of water.
16. The coke oven of claim 13 , wherein the tolerance of the target oven draft is plus or minus 0.01 inches of water.
17. The coke oven of claim 1 , wherein the controller is further operative to vary the targeted oven draft over a coking cycle by stepwise reducing the target oven draft as a function of elapsed time.
18. The coke oven of claim 1 , wherein the controller is further operative to vary the targeted oven draft over a coking cycle by linearly reducing the target oven draft to a smaller value proportional to an elapsed time of the coking cycle.