METHODS AND SYSTEMS FOR EVALUATING ORGANIC CONTAMINANTS IN WATER

Abstract

Methods and systems are described for evaluating the level of organic contaminants in water, and in particular water that is used as boiler feedwater in food processing facilities such as sugar factories. The method includes measuring at least one parameter of the water including pH, conductivity, and/or total organic carbon, and, based on the measured values, determining whether corrective action needs to be taken to reduce the levels of organic contaminants.

Claims

1. A method for evaluating water that is used as boiler feedwater, the method comprising: measuring at least one parameter of the water that is selected from the group consisting of pH, conductivity, total organic carbon (TOC), and oxidation reduction potential (ORP); and based on the at least one measured parameter, determining whether to take corrective action to reduce an amount of organic contaminant in the water and/or mitigate effects of the organic contaminant in the water.

2. The method according to claim 1, the measuring comprising measuring at least one of the pH and the conductivity of the water.

3. The method according to claim 1, further comprising measuring a fluorescence intensity of the water, and determining whether to take the corrective action based on the measured fluorescence intensity.

4. The method according to claim 1, further comprising taking the corrective action when it is determined that the at least one measured parameter changes at a rate that exceeds a threshold value.

5. The method according to claim 3, further comprising taking the corrective action when it is determined that the at least one measured parameter and the fluorescence intensity changes at a rate that exceeds a threshold value.

6. The method according to claim 1, further comprising taking the corrective action when it is determined that the at least one measured parameter exceeds a threshold value.

7. The method according to claim 1, wherein the boiler feedwater includes condensate from an evaporation process.

8. The method according to claim 7, wherein water that is measured includes the condensate.

9. The method of claim 1, further comprising measuring a concentration of at least one organic contaminant in the water and correlating the measured concentration to the at least one measured parameter.

10. The method of claim 9 wherein the measured organic contaminant includes lignins and tannins.

11. The method of claim 1, the measuring comprising measuring the conductivity of the water, and further comprising measuring a fluorescence intensity of the water, and determining whether to take the corrective action based on the measured conductivity and the measured fluorescence intensity.

12. The method of claim 3, wherein measuring the fluorescence intensity includes measuring emission intensity at a wavelength in a range of 380-400 nm.

13. The method of claim 3, wherein measuring the fluorescence intensity includes measuring emission intensity at a wavelength in a range of 340-360 nm.

14. The method of claim 9, wherein the organic contaminant is at least one selected the group consisting of sugars, lignins, tannins, organic acids, and a breakdown product of these compounds.

15. The method of claim 9, wherein the organic contaminant includes at least one of lignins and tannins.

16. An apparatus for evaluating water that is used as boiler feedwater in a food processing facility, the apparatus includes a processor that is programmed to: receive a signal corresponding to at least one measured parameter of the water that is selected from the group consisting of pH, conductivity, total organic carbon (TOC), and oxidation reduction potential (ORP); and based on the received signal corresponding to the at least one measured parameter, generating a signal to control at least one operating parameter of the food processing facility and/or generating a signal that causes a display to display an alert.

17. A method for controlling an amount of an organic contaminant in boiler feedwater used in a boiler of an evaporator stage in a sugar processing facility, the method comprising: measuring at least one parameter of the boiler feedwater that is selected from the group consisting of pH, conductivity, total organic carbon (TOC), and oxidation reduction potential (ORP); and based on the at least one measured parameter, taking at least one corrective action to reduce an amount of organic contaminant in the boiler feedwater and/or mitigate effects of the organic contaminant in the boiler feedwater.

18. The method of claim 17, wherein the at least one corrective action includes changing an operating parameter of a stream in the sugar processing facility, including at least one of flow rate, pH, temperature, and addition of chemicals to the stream.

19. The method of claim 17, wherein the at least one corrective action includes changing a feedwater source to the boiler.

20. The method of claim 17, wherein the at least one corrective action includes taking the boiler offline.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1A is a schematic diagram of a washing water system in a beet sugar factory;

[0011] FIG. 1B is a schematic diagram of a typical beet sugar processing system;

[0012] FIG. 2 is a schematic diagram illustrating the evaporation stage in a typical beet sugar processing system;

[0013] FIG. 3 is a graph showing measured values of fluorescence, conductivity, and pH for a condensate stream of an evaporator in a beet sugar factory;

[0014] FIG. 4 is a graph showing measured values of flow rate, fluorescence, conductivity, and pH for a boiler feedwater stream to an evaporator in a beet sugar factory;

[0015] FIG. 5 is another graph showing measured values of fluorescence, conductivity, and pH for a condensate stream of an evaporator in a beet sugar factory;

[0016] FIG. 6 is a graph showing the correlations between three different fluorescence wavelengths and the concentrations of lignin and tannin in samples from sugar beet factories;

[0017] FIG. 7 is a graph showing the correlations between four different fluorescence wavelengths and the concentrations of sucrose in the thin juice from a sugar beet factory;

[0018] FIG. 8 is a graph showing the correlation between sucrose concentration and lignin/tannin concentration in the thin juice from a sugar beet factory;

[0019] FIG. 9 is a graph showing the correlation between betaine concentration and conductivity in the thin juice from a sugar beet factory;

[0020] FIG. 10 is a graph showing the correlations between four different fluorescence wavelengths and the concentrations of lignins/tannins in a first evaporator condensate stream from a sugar beet factory;

[0021] FIG. 11 is a graph showing the correlations between four different fluorescence wavelengths and the concentrations of lignins/tannins in a second evaporator condensate stream from a sugar beet factory;

[0022] FIG. 12 is a graph showing the correlations between four different fluorescence wavelengths and the concentrations of lignins/tannins in boiler feed water from a sugar beet factory; and

[0023] FIGS. 13A-13C are graphs shown the measured fluorescence intensity at various stages in a sugar beet processing facility over the course of a season.

DETAILED DESCRIPTION OF EMBODIMENTS

[0024] Disclosed embodiments include methods for determining contamination of boiler feedwater in food production facilities such as sugar factories. As indicated in connection with FIG. 2 the boiler feedwater may, in part or in whole, come from condensate from the evaporation process, or it may include water that is used in the washing or extraction stages. These water sources can have organic contaminants that can negatively affect the boiler, including sugars, polymeric carbohydrates, lignins, tannins, organic acids (e.g., betaine), and/or breakdown products of these components. For example, in the case of evaporator condensate, the contaminants may become entrained in the condensate based on leaks, boil-over entering the condenser, and possibly contaminants sublimating in the condenser.

[0025] In one aspect, it has been discovered that the presence of organic contaminants can be accurately detected based on pH, total organic carbon (TOC), and/or conductivity of the water. In another aspect, it was discovered that organic contaminants in water can be detected using optimized fluorescence wavelengths, e.g., that are based on breakdown components from parent contaminants. Thus, it has been discovered that changes in the pH, conductivity, TOC and/or combinations thereof can be correlated with contaminants (including, e.g., sugars, lignins/tannins, betaine and other modified amino acids, and breakdown products) in the water. Fluorescence intensity at optimized wavelengths can likewise be correlated with certain contaminants in the water. Accordingly, each of these detection techniques may be used alone or in combination with each other (i.e., two or more parameters) to more accurately and reliably measure the organic contaminants and to allow for predictive modeling of upcoming plant upsets.

[0026] The pH, conductivity, and fluorescence measurements can be taken with probes that are positioned to measure the condensate from one or more of the evaporators, e.g., the first drip from the first evaporation stage, or the second drip from the second evaporation stage, etc., or are positioned to directly measure the boiler feedwater. Probes that are positioned to directly measure the boiler feedwater can be located at the feedwater off of the first evaporator(s), off the of the second evaporator(s), or off of the raffinate evaporator, for example. The location can be determined by plant piping configurations and/or likely locations of possible contaminants.

[0027] The TOC is a laboratory measurement, and can be performed on water samples taken from a condenser drip or from the boiler feedwater, for example. The TOC can be correlated with other parameters that can be measured in real time, such as the pH, fluorescence, or oxidation reduction potential (ORP), for example.

[0028] FIG. 3 is a graph showing real-time measured values of fluorescence, conductivity, and pH for a condensate stream of an evaporator in a beet sugar factory over five days. The fluorescence is measured at ex/em of 365 nm/470 nm. As can be seen in FIG. 3, in several instances (e.g., 11/16/20 and 11/17/20) abrupt changes in the pH, fluorescence intensity, and conductivity coincide. In this case, the fluorescence intensity and conductivity change inversely to the pH. FIG. 4 shows similar real-time measured values of the boiler feedwater over 7 days, and FIG. 5 shows real-time measured values of another condensate stream for 7 days. In each trial, abrupt changes in two or more of the parameters coincide (e.g., 11/14/200 in FIG. 4, and 11/11/20 in FIG. 5). In some cases, the changes in a parameter can be proportional to other parameters (e.g., FIG. 4), and in some cases the changes can be inversely proportional (e.g., FIG. 3). In either case, it is believed that such abrupt changes correspond to upsets in the water, such as spikes in the contaminants level. The use of pH and/or conductivity values, in addition or as an alternative to fluorescence measurements, can therefore provide reliable indications of contamination events, and can allow detection of contamination events that standard fluorescence detection could miss.

[0029] As indicated above, conventional fluorescence measurements in this field to detect organic contaminants at an ex/em of 365 nm/470 nm. Applicant's copending U.S. patent application Ser. No. 16/622,369, the entirety of which is incorporated by reference herein, describes some suitable fluorescence parameters for detecting lignins and tannins, as well as additional contaminants which are likely breakdown products of lignins and tannins. A fluorescence probe can be used to detect lignins and tannins at excitation wavelengths from 380-400 nm, preferably around 390 nm, and emission wavelengths at 460-480 nm, preferably around 470 nm. Another fluorescence probe can be used to detect likely breakdown products of tannins and lignin at excitation wavelengths in a range of from 260-290 nm, preferably around 275 nm, and emission wavelengths at around 340-360 nm, preferably around 350 nm.

[0030] FIG. 6 is a graph showing the correlations of three different fluorescence ex/em wavelengths (wavelengths 365 nm/470 nm; wavelengths 390 nm/470 nm; wavelengths 275 nm/350 nm) to the concentrations of lignin and tannin in thin juice samples and condensate samples from several U.S. sugar beet factories. The data shows that there is a good correlation between the concentrations of these contaminants and fluorescence intensity at both 365/470 (as has been conventionally used), and at 390/470. As can be seen, the correlation at 390/470 is somewhat better than 365/470 and may be more sensitive than these conventional wavelengths. The correlation at 275/350 is inversely proportional to the lignin/tannin concentration, and it is believed that the 275/350 fluorescence detects breakdown products of lignins and tannins.

[0031] Table 1 below shows raw data of water in several U.S. sugar beet factories at various stages of the production process. The data includes fluorescence measurements at various wavelengths, measured lignin and tannin concentrations, TOC, chemical oxygen demand (COD), pH and conductivity. Table 2 shows similar raw data for water in several sugar cane plants in the United States and Latin America.

TABLE-US-00001 TABLE 1 Intensity Intensity Intensity Max Max Relative at 275 nm, at 365 nm, at 390 nm, Excitation Emission Intensity 350 nm 470 nm 470 nm Sample Type (nm) (nm) (A.U.) (A.U.) (A.U.) (A.U.) Pond 3 Inlet 344 430 13853 1730 10305 7983 Condenser 284 330 21751 15532 2461 1487 Clarifier Underflow 404 494 2609 20 1013 1924 Clarifier Underflow 350 444 17541 2931 15853 14156 Filtered Raffinate 100× dilution 400 478 18601 2 4560 15694 Condensate 264 338 25476 22583 1658 568 Thick Juice 514 576 18248 302 40 45 Condenser to Boiler 274 334 2350 2217 772 536 Thin Juice 394 468 65901 −8 31996 64930 Thin Juice Run #2 394 468 65901 −8 31996 64930 Condensate 316 384 28721 10715 779 261 Condensate Run #2 316 384 28721 10715 779 261 Thin Juice 356 440 46571 359 38664 33908 Condensate 320 384 76781 12119 2404 968 Waste Collection Tank 268 330 6289 4537 1030 666 1st Condensate 274 340 9672 8941 767 206 2nd Condensate 262 338 13805 8923 309 112 CSB drips 318 394 12512 11290 1509 392 Raff Drips 322 386 177877 3451 5717 1736 Thin Juice 362 444 54660 571 46625 39765 Thin Juice 386 464 52593 17 36747 50933 First Evap Stage 264 336 20570 11975 268 126 2nd Drips Second Evap Stage 314 384 12512 9290 327 131 2nd Drips Thin Juice 374 454 44055 280 38050 39173 First Evap Stage 262 336 45167 19733 384 193 2nd Drips Second Evap Stage 262 336 28302 15113 240 95 2nd Drips Radar Panel 262 334 31440 15878 302 126 (Condensate composite) 1st Condensate 270 334 11595 10279 714 300 2nd Condensate 262 334 41168 14436 610 296 CSB drips 316 390 15339 11490 1613 490 Raff Drips 274 336 13495 12191 780 229 Thin Juice 394 466 53943 −4 25071 52716 Evap 19:50? 268 336 10701 9361 336 124 2nd Evap 9:55 262 336 27008 12481 373 155 CSB drips 9:40 274 340 18232 17172 1215 536 Raff Drips 9:35 274 336 8709 7602 296 114 Thin Juice 9:30? 384 464 56743 21 41302 55303 Thin Juice Softened, 388 468 42696 4 35184 52186 Sulfer, Caustic 1:53 First Evap Stage 262 336 23104 12784 307 136 2nd Drips 1:47 Second Evap Stage 262 336 18439 10600 341 151 2nd Drips 1:36 Radar Panel 262 336 16991 10588 289 139 (Condensate composite) 1:33 Thin Juice Softened 394 478 56502 −2 26175 55554 Sulfur Caustic 2:05 pm First Evap Stage 262 336 40196 16692 275 132 2nd Drips 2:01 pm Second Evap Stage 316 384 42913 15157 285 110 2nd Drips 1:53 pm RADAR Panel 1:57 pm 316 384 30390 14810 268 129 Boiler Radar DA 1:40 pm 316 384 68334 10136 280 106 Raff Radar 1:00 pm 274 342 29793 28236 1614 725 Raff Drips 1:07 pm 272 328 9056 7320 180 74 Thin Juice 1:22 pm 396 488 43020 28 24799 41099 Thin Juice Softened 380 464 40684 90 33975 39360 Sulfur Caustic 10:16 am First Evap Stage 314 382 12503 8504 404 227 2nd Drips 10:19 am Second Evap Stage 316 384 11997 7920 355 205 2nd Drips 10:24 am RADAR Panel 10:27 am 264 336 16736 10283 379 225 Thin Juice Softened 390 472 49806 12 30431 49771 Sulfur Caustic 10:32 am First Evap Stage 262 336 29223 14735 366 177 2nd Drips 10:27 am Second Evap Stage 264 334 21153 12375 353 179 2nd Drips 10:29 am RADAR Panel 10:19 am 262 334 27051 13943 339 168 DA Radar 12:37 pm 270 336 7338 6364 233 96 CSB Radar 2:20 pm 268 338 16203 14776 956 351 R1 Drips Raff 2:10 pm 274 332 5859 5179 158 66 Thin Juice 12:30 pm 376 456 47630 64 40069 43639

TABLE-US-00002 TABLE 2 Intensity Intensity Intensity Lignin and Max Max Relative at 275 nm, at 365 nm, at 390 nm, Tannin Max Max Sample Excitation Emission Intensity 350 nm 470nm 470 nm Values TOC Sample Excitation Emission Type (nm) (nm) (A.U.) (A.U.) (A.U.) (A.U.) (ppm) (ppm) Type (nm) (nm) Evaporator 426 516 5420 0 200 1373 Interference 63510 Evaporator 426 516 Supply Supply Juice Juice 1st Evap 382 354 400 379 63 56 0.01 1.1 1st Evap 382 354 Condensate Condensate 2nd Evap 264 332 44573 20294 1097 576 4.4 5.1 2nd Evap 264 332 Condensate Condensate Processing 304 426 1372 747 806 525 0.9 2.6 Processing 304 426 Well Water Well Water Processing 310 430 1328 924 806 519 0.3 — Processing 310 430 Well Water Well Water Processing 310 422 1300 608 684 512 0.3 — Processing 310 422 Well Water Well Water Filtered Filtered Water 264 332 53719 27584 804 417 — — Water 264 332 Water 264 330 24101 11704 701 368 — — Water 264 330 Water 274 334 111322 88645 2617 805 — — Water 274 334 Water 274 334 78575 62187 1671 536 — — Water 274 334 Condensate 266 330 45600 24378 303 152 2.3 — Condensate 266 330 Pan #2 Pan #2 Condensate 262 332 23988 9265 195 97 1.1 — Condensate 262 332 Condensate 262 332 15498 5849 103 56 0.3 — Condensate 262 332 Condensate 270 298 36652 6295 245 119 1.3 — Condensate 270 298 1st Effect 1st Effect Condensate 280 330 501261 342953 5806 1146 4.7 — Condensate 280 330 2nd Effect 2nd Effect Evaporator 1 272 300 43161 9975 296 97 1.4 17 Evaporator 1 272 300 Condenser 262 334 141602 47907 445 225 3.4 447 Condenser 262 334 Condensate 262 334 49196 29325 1275 670 5.2 420 Condensate 262 334 2nd Tank 2nd Tank Dryer 264 332 37058 21496 601 379 1.8 253 Dryer 264 332 Pan 4 280 336 89733 70085 967 602 1.9 122 Pan 4 280 336 Good 270 330 349 243 12 9 0.2 6.6 Good 270 330 Condensate Condensate Bad 262 336 1464 612 27 22 0.3 33 Bad 262 336 Condensate Condensate Syrup before 436 528 24215 −5 10102 15969 85 INT Syrup 436 528 decoloring before decoloring Syrup after 368 440 55020 2979 44237 44404 45 INT Syrup after 368 440 decoloring decoloring Condensate 274 326 1193 896 134 75 1.8 7.8 Condensate 274 326 Clean Clean Condensate 278 320 881 707 157 93 1.7 61 Condensate 278 320 0.1% sugar 0.1% sugar

[0032] Table 3 below shows data of samples taken from the thin juice of a U.S. sugar beet factory over the course of a campaign. The data shows an average max excitation wavelength of 368 nm and an average maximum emission wavelength of 467 nm.

TABLE-US-00003 TABLE 3 Date of Max Max Relative Sample Excitation Emission Intensity pH Sep. 25, 2020 394 468 65901 10.89 Sep. 28, 2020 356 440 46571 7.57 Oct. 28, 2020 386 464 52593 8.44 Sep. 9, 2020 374 454 44055 7.35 Sep. 30, 2020 388 468 42696 8.5 Dec. 7, 2020 394 478 56502 9.13 Dec. 21, 2020 380 464 40684 6.26 Jan. 4, 2021 390 472 49806 8.42 Jan. 19, 2021 398 474 43258 8.6 Feb. 2, 2021 392 466 50894 6.01 Feb. 16, 2021 398 486 35416 8.95

[0033] FIGS. 7-12 show various correlations of data taken from a U.S. sugar beet factory. FIG. 7 is a graph showing the correlation between the measured amount of sucrose in the thin juice and the measured fluorescence intensity of the thin juice from four fluorescence probes—(1) radar probe, 365 nm ex/470 nm em; (2) 316 nm ex/384 nm em; (3) 274 nm ex/350 nm em; and (4) 390 nm ex/470 nm em. The fluorescence intensity at 274/350 shows a good correlation (about 65%) to the amount of sucrose in the in the thin juice.

[0034] FIG. 8 is a graph that shows the correlation of the sucrose concentration in the thin juice to the amount of lignins/tannins in the thin juice. FIG. 8 shows that the concentration of concentration of lignins/tannins has a good correlation with the concentration of sucrose (about 69%).

[0035] FIG. 9 is a graph that shows the correlation of the betaine concentration in the thin juice to the measured conductivity of the thin juice. The betaine concentration exhibits a good correlation with the conductivity (about 67%).

[0036] FIG. 10 is a graph showing the correlation between the measured amount of lignins/tannins in the condensate of a first evaporator and the measured fluorescence intensity at the wavelengths of the four probes identified above. The fluorescence intensity of the radar probe (365/470) shows a good correlation (about 82%) to the amount of lignins/tannins in this condensate stream.

[0037] FIG. 11 is a graph showing the correlation between the measured amount of lignins/tannins in the condensate of a second evaporator and the measured fluorescence intensity at the wavelengths of the four probes identified above. The fluorescence intensity of the radar probe (365/470) shows a good correlation (about 72%) to the amount of lignins/tannins in this condensate stream.

[0038] FIG. 12 is a graph showing the correlation between the measured amount of lignins/tannins in a radar panel sample and the measured fluorescence intensity at the wavelengths of the four probes identified above. The radar panel is located on the boiler feedwater. The fluorescence intensity of the radar probe, 316/384, and 390/470 all show good correlations, respectively at about 84%, 93%, and 81%.

[0039] FIGS. 13A-13C are graphs illustrating the measured fluorescence intensity (275/350) at various stages in a sugar beet processing facility over the course of a campaign. FIG. 13A shows the measured fluorescence intensity of the condensate of the first evaporator, FIG. 13B shows the measured fluorescence intensity of the condensate of the second evaporator, and FIG. 13C shows the measured fluorescence intensity of the boiler feedwater at the radar panel. The graphs illustrate that the fluorescence intensity increases as the campaign progresses, which likely indicates that the concentration of contaminants and lower molecular weight components increases as the beets degrade if purification measures are not increased.

[0040] The parameters of fluorescence, conductivity, pH, TOC/ORP, or a combination thereof can be used to identify, quantify, track, and/or ultimately control those contaminates. In one aspect, these metrics can be used to control operating parameters, such as flow rate, pH, temperature, chemical addition, etc., at various stages to reduce the amount of contaminants in water sources that are used for the boiler feedwater. For example, the carb or lime steps identified above can be changed based on measured values, e.g., by feeding less or more coagulant, based on measured parameters. Likewise, since abrupt changes in one or more of the parameters can indicate spikes in contaminant levels, an operator can evaluate such changes and take corrective actions when necessary, such as adding a base to the water to mitigate pH drops and prevent the feedwater from becoming corrosive, using a different feedwater source (e.g., a different condensate drip), or taking the boiler off-line. Similarly, purification steps can be performed or increased on the boiler feedwater, feedwater source, or thin juice to reduce the overall concentration of contaminant.

[0041] These corrective actions can be taken if one or more of the parameters exceeds threshold values or are outside of preset target ranges. These operations can be automatic by using a processor that is programmed with control software, and inputs signals from the fluorescence probe, conductivity probe, ORP probe, and/or pH probe, determines whether a contamination event has occurred (e.g., if one or more signals exceeds a predetermined threshold, or changes at a predetermined rate), and optionally outputs control signals to control process equipment to correct the contamination event. Additionally, if the processor determines that a contamination event has occurred, it can issue a signal to display an alert or warning to the operator (e.g., on a displayed control dashboard) so that the operator can determine if corrective action should be taken.

[0042] Additionally, evaluating the above-identified parameters at a given facility could, over time, enable operators to predict when the presence of contaminants in water is likely to occur, e.g., based on the time of season, temperature, or process conditions. Accordingly, preventive measures could be taken in advance to limit the amount of contaminants that are likely to enter the boiler feedwater.

[0043] It will be appreciated that the above-disclosed features and functions, or alternatives thereof, may be desirably combined into different systems or methods. Also, various alternatives, modifications, variations or improvements may be subsequently made by those skilled in the art, and are also intended to be encompassed by the disclosed embodiments. As such, various changes may be made without departing from the spirit and scope of this disclosure.