Method for monitoring a tube sheet of a heat exchanger

Abstract

Shell-and-tube devices typically require regular maintenance. Described herein is an automated method for tracking the status of individual tubes during maintenance activities and recording status data for review and analysis. Status data may optionally be reported in real-time summary format and/or used to predict time-to-completion. The method minimizes omission errors and helps to reduce the expense of performing maintenance activities in shell-and-tube devices, including shell-and-tube reactors and heat exchangers.

What is claimed is: 
     
         1 . A method for monitoring a tube sheet comprising a plurality of tube ends arranged in a fixed pattern of rows (R) and columns (C), said method comprising the steps of:
 a) assigning a unique identifier to each of said plurality of tube ends,   b) acquiring an initial digital image (Di) of at least a portion of the tube sheet at an initial acquisition time (Ti),   c) determining a state of an attribute for each of the tube ends within said digital image, wherein the attribute has at least two possible states, and   d) recording data in a relational database for each tube end within said digital image, said data including:
 i. the initial acquisition time (Ti), 
 ii. the unique identifier for the tube end, and 
 iii. the state of the attribute at the initial acquisition time (Ti), 
   wherein the attribute comprises at least one of the following:   a1) visual appearance of markers installed either in or on the tube ends,   b1) luminosity of particulate materials within the tube ends,   c1) texture of particulate materials within the tube ends,   d1) frequency of infrared light emitted from the tube ends,   e1) frequency of UV light emitted from the tube ends,   f1) frequency of UV light reflected from the tube ends, and   g1) installation depth of particulate materials within the tube ends.   
     
     
         2 . The method of  claim 1 , wherein the unique identifier assigned to each of said plurality of tube ends is a set of Cartesian coordinates of the form (row, column). 
     
     
         3 . The method of  claim 1 , wherein steps b) through d) are performed multiple times. 
     
     
         4 . The method of  claim 1 , further comprising a step of illuminating the tube sheet with at least one light source that emits wavelengths of light within a visible light spectrum, an infrared spectrum, or an ultraviolet UV spectrum. 
     
     
         5 . The method of  claim 1 , further comprising a step of positioning at least one digital camera such that at least a portion of the tube sheet lies within a field of view of the at least one digital camera, and wherein the acquiring step is performed using said at least one digital camera. 
     
     
         6 . The method of  claim 5 , wherein the at least one digital camera detects wavelengths of light selected from one or more of the visible light spectrum, the infrared spectrum, or the ultraviolet (UV) spectrum. 
     
     
         7 . The method of  claim 1 , wherein, when the attribute is the installation depth within the tube ends, at least one Non-contact Ranging Device (NRD) is utilized to acquire the initial digital image (Di), and the method further comprises positioning the at least one NRD such that at least a portion the tube sheet lies within a field of measurement of the at least one NRD, and wherein the acquiring step comprises:
 collecting a plurality of distance measurements using said at least one NRD, and   representing at least a portion of said plurality of distance measurements as the initial digital image (Di).   
     
     
         8 . The method of  claim 7 , wherein said at least one NRD is selected from the group consisting of a radar device, a sonar device, a laser scanning (LIDAR) device, and an electron-beam device. 
     
     
         9 . The method of  claim 1 , wherein said tube sheet forms part of a heat exchanger, and said heat exchanger is one of a condenser, reboiler, preheater, boiler, superheater, quench exchanger, Transfer Line Exchanger (TLE), evaporator, waste heat boiler, recuperator, cross-exchanger and process heater. 
     
     
         10 . The method of  claim 1 , wherein said tube sheet forms part of a reaction system for producing either Hydrogen Cyanide or Nitrogen Oxides. 
     
     
         11 . The method of  claim 1 , wherein said tube sheet forms part of a nuclear power reactor. 
     
     
         12 . The method of  claim 1 , further comprising the step of using at least a portion of the data recorded in the relational database to produce one or more of tables, graphs, spreadsheets, and color-coded summary graphics. 
     
     
         13 . The method of  claim 1 , further comprising:
 e) acquiring a later digital image (Dx) of at least a portion of the tube sheet at a later acquisition time (Tx), wherein Tx>Ti,   f) determining a later state of the attribute for each tube end in said later digital image (Dx),   g) creating a later data record in the relational database for each tube end within said later digital image (Dx), said later data record including:
 i. the later acquisition time (Tx), 
 ii. the unique identifier for the tube end, 
 iii. the later state of the attribute at the later acquisition time (Tx), and 
   h) repeating steps e) through g) until said maintenance activity is complete.   
     
     
         14 . The method of  claim 1 , wherein said shell and tube device is utilized to perform a chemical conversion, said chemical conversion selected from the group consisting of:
 i. conversion of propylene to acrolein and/or acrylic acid;   ii. conversion of propane to acrolein and/or acrylic acid;   iii. conversion of glycerol to acrolein and/or acrylic acid;   iv. conversion of tert-butanol, isobutene, isobutane, isobutyraldehyde, isobutyric acid, or methyl tert-butyl ether to methacrolein and/or methacrylic acid;   v. conversion of acrolein to acrylic acid;   vi. conversion of methacrolein to methacrylic acid;   vii. conversion of o-xylene or naphthalene to phthalic anhydride;   viii. conversion of butadiene to maleic anhydride;   ix. conversion of n-butane to maleic anhydride;   x. conversion of indanes to anthraquinone;   xi. conversion of ethylene to ethylene oxide; and   xii. conversion of propylene to propylene oxide.   
     
     
         15 . The method of  claim 1 , wherein said shell and tube device is utilized to perform the oxychlorination of ethylene to 1,2-dichloroethane (EDC). 
     
     
         16 . The method of  claim 1 , further comprising the step of using one or more data records stored in the relational database to produce one or more of tables, graphs, spreadsheets, and color-coded summary graphics. 
     
     
         17 . The method of  claim 1 , further comprising the step of producing performance metrics for the maintenance activity, wherein the producing step comprises calculating and displaying the performance metrics in a table, graph, spreadsheet, or color-coded summary graphic. 
     
     
         18 . The method of  claim 6 , further comprising: 
       positioning a plurality of colored tube caps as markers on the tube ends before acquiring the initial digital image (Di), said plurality of tube caps including tube caps having a first color and tube caps having a second color that is different from the first color, wherein the attribute comprises said visual appearance of markers, and wherein the state of the attribute is the color of the markers. 
     
     
         19 . The method of  claim 18 , further comprising the steps of:
 e) removing and/or installing a colored tube cap on one or more of said plurality of tube ends,   f) acquiring a later digital image (Dx) of at least a portion of the tube sheet at a later acquisition time (Tx), wherein Tx>Ti,   g) determining a later color for each of the tube ends within said later digital image (Dx),   h) creating a later data record in the relational database for each tube end within said later digital image (Dx), said later data record including:
 i. the later acquisition time (Tx), 
 ii. the unique identifier for the tube end, and 
 iii. the later color for the tube end at later acquisition time (Tx), and 
   i) repeating steps e) through h) until said maintenance activity is complete.   
     
     
         20 . The method of  claim 18 , further comprising producing one or more of tables, graphs, spreadsheets, and color-coded summary graphics using one or more of the data records stored in the relational database. 
     
     
         21 . The method of  claim 20 , further comprising transmitting said one or more of tables, graphs, spreadsheets, and color-coded summary graphics to at least one display. 
     
     
         22 . The method of  claim 18 , further comprising predicting time-to-completion of the maintenance activity.