Automatic boiler level controller

• US 20020108440A1
• Filed: 06/29/2001
• Published: 08/15/2002
• Est. Priority Date: 06/30/2000
• Status: Active Grant

• Current Assignee: Clark Reliance Corporation
• Original Assignee: Clark Reliance Corporation
• Inventors: Colman, Mark A., Lee, Thomas E.
• Granted Patent: US 6,666,086 B2
• Time in Patent Office: Days
• US Class Current: 73/304R
• CPC Class Codes: F22B 37/54 De-sludging or blow-down devices F22B37/565 takes precedence
• CPC Class Codes: F22B 37/78 Adaptations or mounting of level indicators level indicators per se G01F
• CPC Class Codes: G01F 23/243 Schematic arrangements of probes combined with measuring circuits
• CPC Class Codes: G05D 9/12 characterised by the use of electric means

Abstract

An improved boiler water-level controller. According to one aspect of the present invention, a positive blowdown signal is presented to indicate to the operator that the alarm probe is in steam; performing blowdown until this indicator turns on helps ensure that the alarm probe is working properly. According to another aspect of the present invention, the controller uses a novel methodology of sensing water level using conductivity probes. An embodiment of this methodology uses the charging and discharging of a capacitor through a resistive value to sense the presence of water.

Claims

1. A water level system, accepting input from at least one conductive level sensor and comprising a processor having at least one input port accepting input from the at least one conductive level sensor via a capacitive circuit including at least one capacitor, said processor determining whether the at least one conductive level sensor is in water or not by reading said input port, said input port being at a first level if the at least one conductive level sensor is in water and said input port being at a second, different level if the at least one conductive level sensor is not in water.

2. A water level system according to claim 1 wherein said capacitive circuit is an RC circuit.

4. A fluid level system according to claim 1 wherein said capacitive circuit is an RC circuit.

3. A fluid level system, accepting input from at least one conductive level sensor and comprising a processor having at least one input port accepting input from the at least one conductive level sensor via a capacitive circuit including at least one capacitor, said processor determining whether the at least one conductive level sensor is in the fluid or not by reading said input port, said input port being at a first level if the at least one conductive level sensor is in the fluid and said input port being at a second, different level if the at least one conductive level sensor is not in the fluid.

5. A water level system, accepting input from at least one conductive level sensor and comprising a processor having at least one input port accepting input from the at least one conductive level sensor via a capacitive circuit including at least one capacitor, said processor determining whether the at least one conductive level sensor is in water or not by reading said input port to determine if said capacitor is charged or not.

6. A water level system according to claim 5 wherein said processor determines whether the at least one conductive level sensor is in water or not by causing said capacitor to be charged and by then reading said input port to determine if said capacitor has been discharged or not.

7. A water level system according to claim 5 wherein said capacitive circuit is an RC circuit.

8. A water level system according to claim 6 wherein said capacitive circuit is an RC circuit.

9. A water level system according to claim 6 wherein said processor further includes a second processor port and further wherein said processor charges said capacitor using at least said second processor port.

10. A water level system according to claim 8 wherein said processor further includes a second processor port and further wherein said processor charges said capacitor using said second processor port.

11. A fluid level system, accepting input from at least one conductive level sensor and comprising a processor having at least one input port accepting input from the at least one conductive level sensor via a capacitive circuit including at least one capacitor, said processor determining whether the at least one conductive level sensor is in fluid or not by reading said input port to determine if said capacitor is charged or not.

12. A fluid level system according to claim 11 wherein said processor determines whether the at least one conductive level sensor is in fluid or not by causing said capacitor to be charged and by then reading said input port to determine if said capacitor has been discharged or not.

13. A fluid level system according to claim 12 wherein said processor further includes a second processor port and further wherein said processor charges said capacitor using at least said second processor port.

15. A water level system according to claim 14, wherein if the at least one sensing I/O port is HIGH, determining that the at least one conductive level sensor is in water and if the at least one sensing I/O port is LOW, determining that the at least one conductive level sensor is not in water.

16. A water level system according to claim 14 wherein said capacitive circuit is an RC circuit.

18. A fluid level system according to claim 14, wherein if the at least one sensing I/O port is HIGH, determining that the at least one conductive level sensor is in the fluid and if the at least one sensing I/O port is LOW, determining that the at least one conductive level sensor is not in the fluid.

20. The method of controlling the blowdown of at least one level sensor according to claim 19, wherein water proximate the at least one level sensor is allowed to rise to the point that the positive blowdown display turns off prior to closing the blowdown valve.

21. The method of controlling the blowdown of at least one level sensor according to claim 19, wherein water proximate the at least one level sensor is allowed to rise to the point that the positive blowdown display turns off prior to releasing the blowdown bypass button.

22. The method of controlling the blowdown of at least one level sensor according to claim 19, wherein water proximate the at least one level sensor is allowed to rise to the point that the positive blowdown display turns off prior to closing the blowdown valve, and thereafter releasing the blowdown bypass button.

23. The method of controlling the blowdown of at least one level sensor according to claim 19, wherein said step of providing a positive blow down display comprises the step of illuminating an indicator.

25. A water level controller for a boiler according to claim 24, wherein said control unit transitions to said blowdown mode responsive to a user actuating an input device.

26. A water level controller for a boiler according to claim 24, wherein said control unit is further characterized by transitioning from said blowdown mode to said normal mode after said control unit is in said blowdown mode for a predetermined period of time.

27. A water level controller for a boiler according to claim 24, wherein said control unit transitions to said blowdown mode responsive to a user actuating an input device and remains in said blowdown mode until the sooner of the user de-actuating the input device or the control unit being in said blowdown mode for a predetermined period of time.

29. A water level controller for a boiler according to claim 28, wherein said control unit transitions to said blowdown mode responsive to a user actuating an input device.

30. A water level controller for a boiler according to claim 28, wherein said control unit is further characterized by transitioning from said blowdown mode to said normal mode after said control unit is in said blowdown mode for a predetermined period of time.

31. A water level controller for a boiler according to claim 28, wherein said control unit transitions to said blowdown mode responsive to a user actuating an input device and remains in said blowdown mode until the sooner of the user de-actuating the input device or the control unit being in said blowdown mode for a predetermined period of time.

14. A water level system, accepting input from at least one conductive level sensor and comprising:

(a) a processor having at least one driver port and at least one sensing I/O port; and

(b) a capacitive circuit connected to said at least one driver port and said at least one sensing I/O port and accepting input from the at least one conductive level sensor, said capacitive circuit having at least one capacitor; and

(c) wherein said processor executes a software routine for determining whether the at least one conductive level sensor is in water or not, comprising the following steps;

i. making the at least one sensing I/O port an output and setting its output HIGH;

ii. setting the output of said at least one driver port HIGH;

iii. making the at least one sensing I/O port an input;

iv. setting the output of said at least one driver port LOW;

V. reading the least one sensing I/O port input;

vi. if the at least one sensing I/O port is at a first logical level, determining that the at least one conductive level sensor is in water; and

vii. if the at least one sensing I/O port is at a second, different logical level, determining that the at least one conductive level sensor is not in water.

17. A fluid level system, accepting input from at least one conductive level sensor and comprising:

(a) a processor having at least one driver port and at least one sensing I/O port; and

(b) a capacitive circuit connected to said at least one driver port and said at least one sensing I/O port and accepting input from the at least one conductive level sensor, said capacitive circuit having at least one capacitor; and

(c) wherein said processor executes a software routine for determining whether the at least one conductive level sensor is in fluid or not, comprising the following steps;

i. making the at least one sensing I/O port an output and setting its output HIGH;

ii. setting the output of said at least one driver port HIGH;

iii. making the at least one sensing I/O port an input;

iv. setting the output of said at least one driver port LOW;

v. reading the least one sensing I/O port input;

vi. if the at least one sensing I/O port is at a first logical level, determining that the at least one conductive level sensor is in the fluid; and

vii. if the at least one sensing I/O port is at a second, different logical level, determining that the at least one conductive level sensor is not in the fluid.

19. A method of performing the blowdown of at least one level sensor, comprising the steps of:

(a) actuating a blowdown bypass button of a level controller;

(b) opening a blowdown valve;

(c) determining that a particular one of the at least one level sensors is in steam;

(d) providing a positive blowdown display responsive to determining that a particular one of the at least one level sensors is in steam;

(e) closing the blowdown valve; and

(f) releasing the blowdown bypass button.

24. A water level controller for a boiler, comprising a control unit, said control unit characterized as follows:

(a) said control unit accepting inputs from a plurality of level sensors;

(b) said control unit having at least two modes, namely a normal mode and a blowdown mode,

i. wherein in said normal mode, said control unit changes an alarm circuit to an alarm state responsive to the water level in the boiler falling below a level sensed by a first level sensor; and

ii. wherein in said blowdown mode, said control unit does not change the alarm circuit to the alarm state responsive to the water level in the boiler falling below the level sensed by the first level sensor, rather said control unit activates a positive blowdown indicator responsive to the water level in the boiler falling below the level sensed by the first level sensor.

28. A water level controller for a boiler, comprising a control unit, said control unit characterized as follows:

(a) said control unit accepting inputs from a plurality of level sensors;

(b) said control unit having at least two modes, namely a normal mode and a blowdown mode,

i. wherein in said normal mode, said control unit controls a pump to pump water into the boiler responsive to levels sensed by at least first and second level sensors and said control unit changes an alarm circuit to an alarm state responsive to the water level in the boiler falling below a level sensed by a third level sensor; and

ii. wherein in said blowdown mode, said control unit does not control the pump to pump water into the boiler responsive to levels sensed by at least first and second level sensors and does not change the alarm circuit to the alarm state responsive to the water level in the boiler falling below the level sensed by the third level sensor, rather said control unit activates a positive blowdown indicator responsive to the water level in the boiler falling below the level sensed by the third level sensor.