Temperature Sensing Sootblower
A temperature sensing sootblower that may be configured as a modification to an existing sootblower or a specially constructed sootblower that, in addition to its normal soot blowing functions, has the capability to measure the flue gas, lance tube, and/or cleaning fluid temperatures. One or more thermocouples or other temperature measuring devices are carried by the soot blower lance tube that is inserted into the boiler. This allows for the temperature of the flue gas, lance tube, and cleaning fluid to be measured as the sootblower lance tube is inserted into and retracted from the boiler. Multiple temperature measuring devices may be located on the sootblower lance to measure the temperature across heat transfer surfaces and at different locations along the lance tube. A data transfer device transmits the temperature measurements from the rotating thermocouple to a non-rotating data acquisition unit for use in boiler cleaning and other operations.
The entrainment of fly ash particles from the lower furnace of an industrial boiler to the convection sections of the boiler is an inevitable process. The accumulation of these particles in the fireside heat exchanger surfaces reduces the boiler thermal efficiency, creates a potentially corrosive environment at the boiler tube surfaces and, if the accumulation is not properly controlled, may also lead to costly unscheduled boiler shutdowns due to plugging of the gas passages.
Knowledge of the flue gas temperatures across the boiler heat transfer surfaces is therefore an important piece of information that can be used to evaluate fireside deposit characteristics, to improve boiler cleaning operation through intelligent deposit removal processes, and to optimize boiler operation and combustion processes. Conventional temperature sensors positioned in fixed locations on boiler walls or other internal boiler structures do not monitor flue gas temperatures across the boiler heat transfer surfaces. There is, therefore, a continuing need for effective ways of monitoring the internal temperature of flue gasses across heat transfer surfaces inside of industrial boilers.
Sootblowers are by far the most widely used equipment to remove the fireside deposit accumulations in industrial boilers, such as oil-fired, coal-fired, trash-fired, waste incinerator, as well as boilers used in paper manufacturing, oil refining, steel, and aluminum smelting and other industrial enterprises. A sootblower consists of a lance tube with one or more nozzles. During the deposit removal process, the sootblower lance rotates and extends through a small opening in the boiler wall, while blowing high pressure cleaning fluid (e.g., steam, air or water) directed into the tube banks. After the lance is fully extended, it rotates in the opposite direction as it retracts to its original inactive state.
The sootblower carriage consists of one or two electric motor(s), a gearbox and a packing housing. The electric motor is the main drive that moves the lance tube forward and backward during the cleaning cycle. The motor converts electrical energy into rotation motion, which is then used by the gearbox to rotate and move the lance tube along the gear rack. As the steam enters a sootblower, it is directed to four components in the following order: poppet valve, feed tube, lance tube, and nozzles. The lance tube is the main component that travels within the boiler while supplying the sootblower nozzles with high pressure steam directed by jets toward the boiler tubes. The lance travel includes insertion into and retraction from the boiler. During the cleaning process, the lance extends into the boiler and forms a structure similar to a cantilevered beam. Hence, the lance has to be designed to have sufficient strength to support its own weight in a high temperature environment.
To avoid overheating the lance tube during internal boiler operation, the blowing fluid, which also acts as a cooling medium, needs to be supplied continuously to the lance. The minimum amount of the cleaning media required to prevent the lance from overheating is known as the minimum cooling flow. The minimum cooling flow of a lance tube depends on the material, the length of the lance tube, the steam and flue gas temperatures. Knowledge of the lance tube temperatures as the lance is being exposed to hot flue gas inside the boiler is very important to prevent lance tube overheating and to devise emergency sootblower retraction control strategy. A continuing need therefore exists for effective ways for monitoring the temperature of the lance tube as the lance is exposed to hot flue gas inside the boiler.
SUMMARY OF THE INVENTIONThe present invention meets the needs described above in a temperature sensing sootblower that includes an elongated lance tube configured to travel adjacent to and across a heat transfer surface in a boiler while directing a cleaning fluid through one or more nozzles toward the heat transfer surface to remove fireside deposits from the heat transfer surface. The lance tube carries a temperature sensor that is configured to obtain temperature measurements of the flue gas within the boiler, lance tube, and/or cleaning fluid while the lance is located within the boiler. A boiler cleaning controller may control boiler cleaning operations based on the temperature measurements. A data acquisition unit typically receives and records the temperature measurements from the temperature sensor and transmits the temperature measurements to the boiler cleaning controller.
The temperature sensing sootblower also includes a data transfer device that transfers the temperature measurements from the temperature sensor to the data acquisition unit while the temperature sensor rotates with the lance tube. In particular, the data transfer device may be a slip ring fixed to the lance tube.
To measure the temperature of the flue gas as opposed to the lance tube and avoid the cooling effect of the cleaning fluid on the flue gas, the temperature sensing sootblower may include a lance tube extension supporting the temperature sensor beyond a leading end of the lance tube in an insertion direction of the lance tube. The lance tube extension may also support the temperature sensor beyond the lance tube extension in the insertion direction.
The temperature sensing sootblower may include a groove in the lance tube and the temperature sensor may be a thermocouple positioned within the grove. A welding rod may be positioned above the thermocouple within the grove with an overlay weld positioned above the welding rod sealing the thermocouple within the grove.
The invention may also be practiced as a temperature sensing sootblower that includes an elongated lance tube and a temperature sensor carried by the lance tube configured to obtain temperature measurements of the lance tube while the lance tube travels within the boiler. The flue gas temperature sensor and the lance tube temperature sensor may also be combined, such that the lance tube carries a first temperature sensor configured to obtain temperature measurements of flue gas within the boiler across the heat transfer surface as the lance tube travels across the heat transfer surface and a second temperature sensor configured to obtain temperature measurements of the lance tube while the lance tube travels within the boiler. In this case, the temperature sensors may be a pair of thermocouples located in a stranded wire positioned within the grove. Multiple temperature sensors also may be located along the lance tube if desired.
In addition, the temperature sensing sootblower may also include a thermocouple in contact with the lance tube for measuring the temperature of the lance tube and/or a thermocouple extending through a hole in the lance tube into an interior of the lance tube for measuring the temperature of a cleaning fluid inside the lance tube. The boiler cleaning controller may be configured to retract the lance tube in response to temperature measurements from the temperature sensor indicating that the lance tube has exceeded a predetermined temperature.
In view of the foregoing, it will be appreciated that the present invention avoids the drawbacks of prior boiler temperature measuring systems and provides an improved temperature sensing sootblower. The specific techniques and structures for creating the temperature sensing sootblowers, and thereby accomplishing the advantages described above, will become apparent from the following detailed description of the embodiments and the appended drawings and claims.
This invention can be embodied in a temperature sensing sootblower that may be configured as a modification to an existing sootblower or a specially constructed sootblower that, in addition to its normal soot blowing functions, has the capability to measure the flue gas, lance tube, and/or cleaning fluid temperatures. One or more thermocouples or other temperature measuring devices are carried by the sootblower lance tube that travels within the boiler. This allows for the temperature of the flue gas, lance tube, and/or cleaning fluid to be measured as the sootblower lance tube is inserted into and retracted from the boiler. Multiple temperature measuring devices may be located on the sootblower lance to measure the temperature across heat transfer surfaces and at different locations along the lance tube. A data transfer device transmits the temperature measurements from the rotating thermocouple to a non-rotating data acquisition unit for use in boiler cleaning and other operations.
A data transfer device, such as a slip ring, is used to transfer the signal from the thermocouple to a data acquisition unit located on the non-rotating part of the sootblower. The invention may also be used in sootblowers that are partially inserted in the boiler (sometimes called half-track sootblowers). It may also be used in sootblowers that are continually inserted into the boiler gas path. The temperature sensor may be a thermocouple, a Resistance Temperature Detector (RTD), or other suitable type of sensing device that is attached to the lance tube of the sootblower.
To measure the temperature of the flue gas and the lance tube inside the boiler, the temperature sensing sootblower 10 carries temperature sensors, in this illustration a multi strand thermocouple 20 that extends longitudinally along the lance tube. The thermocouple is connected to a data transfer device, in this illustration a slip ring 22 that transfers the temperature measurements from the thermocouple to a data acquisition unit 24 while the thermocouple rotates with the lance tube. The data acquisition unit 24, in turn, transmits the temperature measurements to a boiler cleaning controller 25 or other processor that may use the measurements for a variety of purposes, such as displaying the temperature profile across heat transfer surfaces inside the boiler, activating sootblowers and other boiler cleaning equipment, adjusting boiler operation, retracting the lance tube to prevent overheating, and so forth. As the data acquisition unit 24 includes a processor, it may create temperature and perform some of these functions.
The thermocouple 20 is typically a stranded wire containing a number of two-wire thermocouples allowing for multiple temperature sensing locations 26 along the lance tube. For example, the thermocouple may include six wires providing three Type K thermocouples. This provides knowledge of the lance tube temperature so that the lance tube can be retracted to prevent overheating. The temperature along the lance tube may be monitored at multiple locations, as desired.
The thermocouple may also include a boiler gas monitoring location 30 positioned beyond the tip of the lance in the lance insertion direction. To obtain the temperature of the boiler flue gas rather than the lance tube, a lance tube extension 28 supports the thermocouple beyond the tip of the lance in the lance insertion direction. The thermocouple also extends a bit beyond the lance tube extension 28 so that the temperature monitoring location 30 is supported in the flue gas without physically touching the lance tube extension. For example, the lance tube extension 28 may extend four to six inches beyond the tip of the lance and the thermocouple 20 may extend another half inch to the boiler gas monitoring location 30. The lance tube extension 28 may also include one or more vents 34 to for cooling purposes. The lance tube extension is typically made from the same type of material as the lance tube and welded onto the tip of the lance.
In view of the foregoing, it will be appreciated that present invention provides significant improvements in sootblowers and boiler temperature monitoring systems and that numerous changes may be made therein without departing from the spirit and scope of the invention as defined by the following claims.
It will be appreciated that Routine 1100 may be implemented for an initial cleaning cycle and routine 1200 may be implemented to further clean any surfaces or portions of that were not fully cleaned during an initial cleaning cycle. Routines 1100 and 1200 may also be combined into a single routine implementing cleaning based on absolute and differential temperatures at the same time.
Claims
1. A temperature sensing sootblower, comprising:
- an elongated lance tube configured to travel within a boiler while directing a cleaning fluid through one or more nozzles toward the heat transfer surface to remove fireside deposits from the heat transfer surface;
- a temperature sensor carried by the lance tube within the boiler configured to obtain temperature measurements of flue gas within the boiler while the lance tube is located within the boiler.
2. The temperature sensing sootblower of claim 1, wherein the temperature sensor is configured to obtain temperature measurements of the flue gas within the boiler while the lance tube travels within the boiler.
3. The temperature sensing sootblower of claim 2, further comprising a boiler cleaning controller configured to adjust the boiler cleaning operation in response to the temperature measurements from the temperature sensor.
4. The temperature sensing sootblower of claim 3, further comprising a data acquisition unit for receiving and recording the temperature measurements from the temperature sensor and transmitting the temperature measurements to the boiler cleaning controller.
5. The temperature sensing sootblower of claim 4, wherein the lance tube rotates and the data acquisition unit is fixed to a non-rotating structure, further comprising a data transfer device for transferring the temperature measurements from the temperature sensor to the data acquisition unit while the temperature sensor rotates with the lance tube.
6. The temperature sensing sootblower of claim 5, wherein the data transfer device comprises a slip ring fixed to the lance tube.
7. The temperature sensing sootblower of claim 1, further comprising a lance tube extension supporting the temperature sensor beyond a leading end of the lance tube in an insertion direction of the lance tube.
8. The temperature sensing sootblower of claim 7, wherein the lance tube extension supports the temperature sensor beyond the lance tube extension in the insertion direction.
9. The temperature sensing sootblower of claim 1, further comprising a groove in the lance tube, wherein the temperature sensor comprises a thermocouple positioned within the grove.
10. The temperature sensing sootblower of claim 9, further comprising a welding rod positioned above the thermocouple within the grove and an overlay weld positioned above the welding rod sealing the thermocouple within the grove.
11. The temperature sensing sootblower of claim 1, further comprising a second thermocouple in contact with the lance tube for measuring the temperature of the lance tube.
12. The temperature sensing sootblower of claim 1, further comprising a second thermocouple extending through a hole in the lance tube into an interior of the lance tube for measuring the temperature of a cleaning fluid inside the lance tube.
13. The temperature sensing sootblower of claim 1, further comprising:
- a second thermocouple in contact with the lance tube for measuring the temperature of the lance tube; and
- a third thermocouple extending through a hole in the lance tube into an interior of the lance tube for measuring the temperature of a cleaning fluid inside the lance tube.
14. A temperature sensing sootblower, comprising:
- an elongated lance tube configured to travel within a boiler while directing a cleaning fluid through one or more nozzles toward a heat transfer surface to remove fireside deposits from the heat transfer surface;
- a temperature sensor carried by the lance tube within the boiler configured to obtain temperature measurements of the lance tube while the lance tube is located within the boiler.
15. The temperature sensing sootblower of claim 14, wherein the temperature sensor is configured to obtain temperature measurements of the lance tube while the lance tube travels within the boiler.
16. The temperature sensing sootblower of claim 14, further comprising a boiler cleaning controller configured to increase the flow rate of the blowing medium and/or to retract the lance tube in response to temperature measurements from the temperature sensor indicating that the lance tube has exceeded a predetermined temperature.
17. The temperature sensing sootblower of claim 16, further comprising a data acquisition unit for receiving and recording the temperature measurements from the temperature sensor and transmitting the temperature measurements to the boiler cleaning controller.
18. The temperature sensing sootblower of claim 17, wherein the lance tube rotates and the data acquisition unit is fixed to a non-rotating structure, further comprising a data transfer device for transferring the temperature measurements from the temperature sensor to the data acquisition unit while the temperature sensor rotates with the lance tube.
19. The temperature sensing sootblower of claim 18, wherein the data transfer device comprises a slip ring fixed to the lance tube.
20. The temperature sensing sootblower of claim 14, further comprising a groove in the lance tube, wherein the temperature sensor comprises a thermocouple positioned within the grove.
21. The temperature sensing sootblower of claim 20, further comprising a welding rod positioned above the thermocouple within the grove and an overlay weld positioned above the welding rod sealing the thermocouple within the grove.
22. A temperature sensing sootblower, comprising:
- an elongated lance tube configured to travel within a boiler while directing a cleaning fluid through one or more nozzles toward a heat transfer surface to remove fireside deposits from the heat transfer surface;
- a temperature sensor extending through a hole in the lance tube into an interior of the lance tube for measuring the temperature of a cleaning fluid inside the lance tube while the lance tube is located within the boiler.
23. The temperature sensing sootblower of claim 22, wherein the temperature sensor is configured to obtain temperature measurements of the cleaning fluid inside the lance tube while the lance tube travels within the boiler.
24. The temperature sensing sootblower of claim 22, further comprising a groove in the lance tube, wherein the temperature sensor comprises a thermocouple positioned within the grove.
25. The temperature sensing sootblower of claim 23, further comprising a welding rod positioned above the thermocouple within the grove and an overlay weld positioned above the welding rod sealing the thermocouple within the grove.
Type: Application
Filed: Jan 21, 2011
Publication Date: Nov 28, 2013
Inventors: Charlie L. Breeding (Signal Mountain, TN), Danny S. Tandra (Johns Creek, GA), Bruce K. Townsend (Flowery Branch, GA), Charles A. Strawn (Conyers, GA)
Application Number: 13/980,838
International Classification: F22B 37/48 (20060101); F28G 15/00 (20060101); F22B 37/56 (20060101);