Method and system for monitoring the mass changes of heat exchangers of a steam boiler

Patent metadata

Field	Value
Publication number	US-10132495-B2
Application number	US-201414898050-A
Country	US
Kind code	B2
Filing date	Jun 10, 2014
Priority date	Jun 11, 2013
Publication date	Nov 20, 2018
Grant date	Nov 20, 2018

Abstract

A method and a system for monitoring the mass changes of a heat exchanger bank of a steam boiler. The heat exchanger bank is supported by hanger rods and support beams to the frame beams of the steam boiler. In the method, the web plates of the support beams are provided with strain gages for measuring the changes in the strain state generated in the support beams by the mass of the heat exchanger bank. The system includes strain gages fixed to the web plates of the support beams for measuring the changes in the strain state generated in the support beam by the mass of the heat exchanger bank, data logging means for logging the measurement data and a computer or a corresponding calculation unit for processing the measurement data.

First claim

The invention claimed is:

1. A method for monitoring mass changes of a heat exchanger bank of a steam boiler having an upper section including frame beams supporting support beams, wherein the support beams rest on the frame beams at support points,
wherein the heat exchanger bank is supported by vertical hanger rods, and the vertical hanger rods are supported by the support beams, the method comprising:
monitoring strain in vertical support elements of the support beams by strain gages mounted to the vertical support elements, wherein the strain gages are each located a horizontal distance from a nearest one of the support points no greater than a vertical width of the vertical support element, and
using signals from the strain gages which indicate the strain in the vertical support elements to calculate a change in the mass of the heat exchanger bank.

2. The method according to claim 1 , wherein the monitoring of strain includes monitoring changes of a strain state at each of the support points by four strain gages of the strain gages proximate each of the support points, wherein the four of the strain gauges form a Wheatstone full bridge connection.

3. The method according to claim 2 , wherein two of the four strain gauges are provided in a direction of a principal strain and another two of the four strain gauges are provided perpendicularly to said direction of the principal strain.

4. The method according to claim 3 , wherein the principal strain is determined by a finite-element method.

5. The method according to claim 1 , wherein at least one of the support beams includes a parallel pair of the vertical support elements, wherein each of the parallel pair of the vertical support elements has mounted thereto a respective one of the strain gages.

6. The method according to claim 1 , wherein the strain gauges are each located on a respective one the a vertical support elements at a point to which a principal strain provided by a support force (RFEM) of one of the frame beams is applied at an angle of 45 degrees.

7. The method according to claim 1 , further comprising calibrating a mass measurement system by placing a known mass in a known position on one of the support beams.

8. The method according to claim 7 , further comprising calibrating the mass measurement system by a finite-element method.

9. A system for monitoring mass changes of a heat exchanger bank of a steam boiler, wherein the steam boiler includes an upper network of horizontally oriented frame beams and support beams extending over and supported by the frame beams at support points where the support beams attach to the frame beams,
wherein the heat exchanger bank is suspended below the network by vertical hanger rods connected to and hanging down from the support beams;
strain gauges fixed to vertical support elements of the support beams and each of the strain gauges located a horizontal distance from a nearest one of the support points no greater than the vertical width of the vertical support element to which the strain gauge is fixed,
wherein the strain gages are configured to measure changes of a strain state in one or more of the support beams due to the mass of the heat exchanger bank;
a data logger configured to log the measurements of the strain gauges, and
a computer configured to process the measurement data.

10. A method to detect a mass change of a heat exchanger bank suspended in a steam boiler,
wherein the steam boiler includes an upper network of frame beams and support beams extending across the frame beams and resting on the frame beams at support points,
wherein the support beams each include an upper flange, a lower flange and a vertical web plate joining the upper flange to the lower flange, and the lower flange rests on the frame beams;
wherein the heat exchanger bank is suspended below the upper network of frame beams and support beams by vertical hanger rods, and the vertical hanger rods are attached to the upper flange of the support beams, the method comprising:
monitoring strain in the vertical web plate of at least one of the support beams by strain gages mounted to the vertical web plates at locations proximate the support points, wherein each of the locations on the vertical web plates are a horizontal distance from a nearest one of the support points no greater than the vertical width of the web plate, and
detecting a change in a mass of the heat exchanger bank using signals generated by the strain gages, wherein the signals indicate a strain on the vertical web plates to which is attached the strain gage generating the signal.

11. The method of claim 10 wherein the detection of the change in the mass includes comparing the signals from the strain gages on a first one of the vertical support beams to the signals from the strain gages on a second one of the vertical support beams, wherein the first one is upstream of the second one in a flow direction through the steam boiler.

12. The method of claim 11 further comprising controlling a soot blowing operation to remove deposits on the heat exchanger bank.

13. The method of claim 10 further comprising using the detected change in the mass to initiate at least one of a soot blowing operation, a temporary cooling cycle of the steam boiler and a shut-down of the steam boiler.

14. The method of claim 1 wherein each of the strain gages is adjacent a corresponding hole in the support element on which the strain gauge is attached.

15. The system of claim 9 wherein each of the strain gages is adjacent a corresponding hole in the support element on which the strain gauge is attached.

16. The method of claim 10 wherein each of the strain gages is adjacent a corresponding hole in the vertical web plate on which the strain gauge is attached.

Assignees

• Andritz Oy

Inventors

• Pollanen Ilkka

Classifications

• G01G19/52

  Weighing apparatus combined with other objects, e.g. furniture (with walking sticks A45B3/08) · CPC title

• G01G19/14

  for weighing suspended loads (G01G3/00 takes precedence; incorporation of weighing devices in cranes B66C1/40, B66C13/16) · CPC title

• F22B37/56 Primary

  Boiler cleaning control devices, e.g. for ascertaining proper duration of boiler blow-down · CPC title

• F22B37/244

  for water-tube steam generators suspended from the top · CPC title

• G01G19/18

  having electrical weight-sensitive devices · CPC title