CN101696939A - Method for eliminating interference in measurement of micro urea in boiler feed water from diamine - Google Patents
Method for eliminating interference in measurement of micro urea in boiler feed water from diamine Download PDFInfo
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- CN101696939A CN101696939A CN200910102822A CN200910102822A CN101696939A CN 101696939 A CN101696939 A CN 101696939A CN 200910102822 A CN200910102822 A CN 200910102822A CN 200910102822 A CN200910102822 A CN 200910102822A CN 101696939 A CN101696939 A CN 101696939A
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- diamine
- urea
- iodine
- feed water
- boiler feed
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Abstract
The invention discloses a method for eliminating interference in the measurement of micro urea in boiler feed water from diamine. The method comprises: iodine and sodium thiosulfate are used as masking agents; and during the measurement of the micro urea in the boiler feed water, solution of iodine is added into a boiler feed water sample first to allow the iodine to react with the diamine completely, then solution of sodium thiosulfate is added to remove residual iodine till the solution is colorless, and thus the interference from the diamine is eliminated. The method is suitable to be used when the concentration of the diamine in the boiler feed water sample is smaller than 50mg/L. The added solution of iodine is 0.01 mol/L solution of iodine. The complete reaction time of the iodine and the diamine is 18 minutes. The concentration of the added solution of sodium thiosulfate is 0.005 mol/L. The method provided by the invention improves the accuracy the result of the analysis of the micro urea in boiler feed water, can be used for correctly instructing production, ensures steam quality, can create great economic benefits and is applicable to urea production enterprises.
Description
Technical field
The present invention is relevant with the micro urea concentration determination, and is furthermore relevant with micro urea concentration determination in the boiler feed water, especially with boiler feed water in when having micro-diamine to exist the assay determination of micro urea concentration relevant.
Background technology
Reclaim condensed fluid from humidification system in the boiler feed water, or after otherwise urea enters in the boiler, partly decomposition is produced ammonia, cause that ammonia content exceeds standard in the Boiler Steam, cause processing apparatus corrosion down.Undecomposed urea will fall in the boiler, cause boiler corrosion and boiler blowdown to increase, and increase production cost, cause environmental pollution simultaneously, therefore need the strict control of urea content in the boiler feed water, and the accuracy of urea analysis to measure data seems particularly important.When we adopt the paradime thylaminobenzaldehyde colorimetric method for determining to be mixed with in the solution of diamine micro urea concentration, in acid solution, urea, diamine all generate yellow azo-compound with the paradime thylaminobenzaldehyde reaction, the absorption spectrum of these two kinds of coloring matters under visible region 430nm wavelength is overlapped, cause urea measured value higher greatly (the 1mg/L diamine is measured and can be reached about 2000mg/L by ureometry), have a strong impact on the urea analysis result accuracy.As seen, micro-diamine can be measured to produce greatly and disturb this.
By inspection information as can be known: the aqueous solution of (1) diamine has strong reducing property, can make the iodine reducing decoloration, and itself resolves into nitrogen diamine; When (2) diamine is measured the generation interference to ammonia concentration analysis in the aqueous solution, can add iodine liquid and eliminate.But up to now, do not find as yet to relate to the method for diamine, do not measure the patent of the technical scheme application of micro urea in the boiler feed water yet the interference eliminated of urea assay determination.
Summary of the invention
The purpose of this invention is to provide a kind of diamine of eliminating to measuring the method that micro urea disturbs in the boiler feed water, improve micro urea assay determination result precision in the boiler feed water to reach, accurate instruction production, thus improve the economic benefit of manufacturing enterprise.
The inventor after deliberation, the test find a kind of material as screening agent, it not with urea generation chemical reaction, can react with diamine, resultant of reaction does not disturb urea to measure with urea generation chemical reaction yet, thereby eliminate diamine the mensuration of micro urea in the boiler feed water is disturbed, improved the urea analysis result accuracy.
Therefore, the elimination diamine that the inventor provides is as screening agent with iodine and sodium thiosulfate to measuring micro urea disturbs in the boiler feed water method, in measuring boiler feed water during micro urea, in the boiler feed water water sample, add iodine solution earlier, after allowing iodine and diamine react completely, add hypo solution again and remove unnecessary iodine, drip, can eliminate diamine and disturb to colourless.Its reaction principle is as follows:
N
2H
4+2I
2＝4HI+N
2
I
2+2Na
2S
2O
3＝2NaI+Na
2S
4O
6
Said method is applicable to that diamine concentration is less than the situation of 50mg/L in the boiler feed water water sample.
The iodine solution concentration that adds in the said method is 0.01mol/L.
The time of iodine and diamine reaction is 18min in the said method, reacts completely.
The hypo solution concentration that adds in the said method is 0.005mol/L.
Elimination diamine provided by the invention has improved boiler feed water micro urea analysis result accuracy to measuring the method that micro urea disturbs in the boiler feed water, in order to accurate instruction production, guarantees steam quality, can produce favorable economic benefit.Be applicable to urea production enterprise.
Embodiment
Embodiment 1 covers worn-out agent (iodine and sodium thiosulfate) urea is measured interference experiment
Pipetting two groups of different volumes concentration is 1.00mg/mL urea standard solution, directly measure its absorbance (A1) for one group by measuring the urea method, another group adds 0.5mL 0.01mol/L iodine solution respectively, place 18min, allow its back that reacts completely drip to colourless back and measure its absorbance (A2), and the gained measurement result is done linear regression analysis by the method for measuring urea with 0.005 hypo solution.The result is as follows:
Table 1 urea typical curve tables of data
Concentration of standard solution: 1ml=1.00mg urea
| Sequence number | ??0 | ??1 | ??2 | ??3 | ??4 | ??5 |
| Standard solution (mL) | ??0.000 | ??5.00 | ??10.00 | ??15.00 | ??20.00 | ??25.00 |
| ??Ur??(mg) | ??0.00 | ??5.00 | ??10.00 | ??15.00 | ??20.00 | ??25.00 |
| Absorbance (A1) | ??0.000 | ??0.042 | ??0.084 | ??0.130 | ??0.166 | ??0.211 |
| Absorbance (A2) | ??0.000 | ??0.043 | ??0.085 | ??0.128 | ??0.170 | ??0.209 |
Annotate A1: the measured absorbance of different volumes urea standard solution former state,
A2: different volumes urea standard solution former state adds measured absorbance behind iodine, the hypo solution.
Curve check and judgement: get regression equation by least square method:
A1＝b1X+a1＝0.008417C+0.0002857
1, coefficient R 1=0.9997 is qualified
2, intercept is up to the standards
A2＝b2X+a2＝0.008394C+0.0009048
Curve check and judgement:
1, coefficient R 2=0.9997 is qualified
2, intercept is up to the standards
B1, b2 deviation＜5% are in the permissible variation
From above conclusion as can be known, the reagent of adding is measured urea and is not produced interference.
Embodiment 2 diamines with cover worn-out agent reaction test
Pipetting two groups of different volumes concentration is 1.000 μ g/mL diamine standard solution, directly measure its absorbance (in A1) for one group by measuring the urea method, another group adds 0.5mL 0.01mol/L iodine solution respectively, place 18min, allow its back that reacts completely drip to colourless back and measure its absorbance (in A2), the results are shown in Table 2 by the method for measuring urea with the 0.005mol/L hypo solution.
Table 2 screening agent and diamine reaction contrast table
Concentration of standard solution: 1ml=0.00100mg diamine
| Sequence number | ??0 | ??1 | ??2 | ??3 | ??4 | ??5 |
| Standard solution (mL) | ??0.000 | ??5.00 | ??10.00 | ??15.00 | ??20.00 | ??25.00 |
| Diamine (μ g) | ??0.00 | ??5.00 | ??10.00 | ??15.00 | ??20.00 | ??25.00 |
| Absorbance (A1) | ??0.00 | ??0.093 | ??0.200 | ??0.260 | ??0.300 | ??0.450 |
| Absorbance (A2) | ??0.000 | ??0.000 | ??0.002 | ??0.000 | ??0.001 | ??0.002 |
As can be known from the above table, the A1 value is far longer than A2, its absorbance was zero after worn-out agent was covered in the adding of different amount diamine mark liquid, (0.001,0.002 absorbance is the error that analytical instrument allows, can be considered zero handles), illustrate that screening agent and diamine react completely, excessive cover worn-out agent, product do not disturb urea to measure with the paradime thylaminobenzaldehyde developer reaction generation absorbance of measuring the urea use yet, promptly cover worn-out agent and can decompose diamine fully, chromogenic reaction does not take place yet and disturbs Determination of Urea in decomposition product, disturbs thereby thoroughly eliminate diamine.
Embodiment 3 mark-on recovery tests
To 25.00mL boiler feed water sample; Identical boiler feed water sample 25.00mL adds 0.5mL 0.01mol/L iodine solution, places 18min, allows its back that reacts completely drip to colourless with the 0.005mol/L hypo solution, obtains treatment samples; Different volumes urea mark liquid; Add different volumes urea mark liquid in the above-mentioned treatment samples and measure its absorbance respectively, see table 3 for details and (respectively be designated as A by measuring the urea method
Sample 1,A
Sample 2, A
Mark,A
Sample 2+ mark.):
The rate test card of table 3 time
| Sequence number | ??A Sample 1 | ??A Sample 2 | ??A Mark | ??A Sample 2+ mark | The recovery (%) |
| ??1 | ??0.136 | ??0.063 | ??0.197 | ??0.263 | ??95 |
| ??2 | ??0.130 | ??0.000 | ??0.213 | ??0.198 | ??93 |
| ??3 | ??0.198 | ??0.023 | ??0.242 | ??0.266 | ??97 |
| ??4 | ??0.146 | ??0.000 | ??0.362 | ??0.362 | ??100 |
| ??5 | ??0.165 | ??0.011 | ??0.254 | ??0.265 | ??101 |
| ??6 | ??0.163 | ??0.019 | ??0.305 | ??0.300 | ??92 |
| ??7 | ??0.189 | ??0.010 | ??0.287 | ??0.280 | ??94 |
| ??8 | ??0.187 | ??0.009 | ??0.309 | ??0.296 | ??93 |
| ??9 | ??0.166 | ??0.008 | ??0.314 | ??0.306 | ??95 |
| Sequence number | ??A Sample 1 | ??A Sample 2 | ??A Mark | ??A Sample 2+ mark | The recovery (%) |
| ??10 | ??0.230 | ??0.013 | ??0.249 | ??0.263 | ??96 |
| ??11 | ??0.240 | ??0.011 | ??0.378 | ??0.389 | ??96 |
| ??12 | ??0.360 | ??0.026 | ??0.208 | ??0.233 | ??102 |
| ??13 | ??0.231 | ??0.023 | ??0.222 | ??0.245 | ??98 |
| ??14 | ??0.199 | ??0.000 | ??0.197 | ??0.187 | ??95 |
| ??15 | ??0.178 | ??0.015 | ??0.306 | ??0.323 | ??90 |
| ??16 | ??0.135 | ??0.006 | ??0.256 | ??0.263 | ??92 |
| ??17 | ??0.139 | ??0.008 | ??0.190 | ??0.199 | ??93 |
| ??18 | ??0.165 | ??0.009 | ??0.176 | ??0.185 | ??103 |
| ??19 | ??0.170 | ??0.008 | ??0.236 | ??0.256 | ??105 |
Data as can be seen from above table: (1) for boiler feed water, adds to cover worn-out agent and cover worn-out agent measurement result and differ greatly with not adding, and reaches as high as more than 1000 times (A
Sample 1With A
Sample 2Compare as can be known) do not disturb if do not eliminate diamine, to not have the erroneous judgement of urea situation to be decided to be and urea will be arranged (situation of sequence number 2,14 in the table), with urea content low think the urea content height by mistake, instruct mistakenly and produce, callable condensed fluid is not reclaimed, cause and to work as the reusable condensed fluid of pure water in a large number and waste, increase enterprise's production cost, cause economic loss to manufacturing enterprise; (2) accuracy of method is higher, and the recovery can satisfy the production control requirement between 90%～105%.
This method has been eliminated diamine the mensuration of micro urea in the boiler feed water has been disturbed, and has improved urea assay determination result precision in the boiler feed water, but accurate instruction production.
Embodiment 4
On July 18th, 2009, redly day be combined to humidification system and break down, cause humidification to reclaim that micro urea enters the boiler feed water of auxilliary pot in the condensed fluid, Boiler Steam ammonia exceeds standard.Must the auxilliary pot of blowdown purified treatment of not stopping that feeds water in the processing procedure, for confirming the blowdown disposition, be needed analyze monitoring to micro urea concentration in the boiler feed water.Measurement result is as follows:
Auxilliary pot feedwater of table 47.18-7.22 day micro urea analysis result table (mg/L)
| Time | ??7.18. ??8:00 | ??7.18 ??16:00 | ??7.19 ??8:00 | ??7.19 ??16:00 | ??7.20 ??8:00 | ??7.20 ??16:00 | ??7.21 ??8:00 | ??7.21 ??16:00 | ??7.22 ??8:00 | ??7.22 ??16:00 |
| The result | ??635 | ??458 | ??426 | ??326 | ??328 | ??385 | ??329 | ??346 | ??346 | ??346 |
Calculate and technological flow analysis is judged from technology theory, auxilliary pot feeds water and answers the blowdown purified treatment to finish about July 19 is during 16:00, and wherein micro urea content should be very low, but to July 20,
21, the auxilliary pot feedwater micro urea content analysis data that 22 days " analytical test department " reports and submits are still high, through cause investigation in many ways, may be because the analysis data are inaccurate, oxygen scavenger---diamine has produced larger interference to auxilliary pot in measuring auxilliary pot feedwater micro urea process, be analyzed test immediately and confirm that test procedure and test findings are as follows:
Readopt auxilliary pot feedwater water sample and auxilliary pot feedwater in 18 to 22 on July 23 and retain a water sample and respectively get 25mL and measure wherein micro urea concentration value, be designated as C
1(mg/L), get above same auxilliary pot and add 0.5mL 0.01mol/L iodine solution respectively for water sample 25mL, place 18min, allow its back that reacts completely drip to the sample water white transparency and measure its micro urea concentration value, be designated as C with 0.005 hypo solution
2(mg/L), the result sees for details as follows:
Two kinds of method comparative analyses of the auxilliary pot feedwater micro urea of table 5 are table (mg/L) as a result
| Time | ??7.18 ??8:00 | ??7.18 ??16:00 | ??7.19 ??8:00 | ??7.19 ??16:00 | ??7.20 ??8:00 | ??7.20 ??16:00 | ??7.21 ??8:00 | ??7.21 ??16:00 | ??7.22 ??8:00 | ??7.22 ??16:00 | ??7.23 ??8:00 | ??7.23 ??16:00 |
| ??C 1 | ??630 | ??448 | ??416 | ??306 | ??318 | ??375 | ??319 | ??326 | ??336 | ??326 | ??335 | ??298 |
| ??C 2 | ??620 | ??430 | ??402 | ??1 | ??0 | ??1 | ??2 | ??0 | ??1 | ??0 | ??0 | ??1 |
Beginning to the auxilliary pot feedwater on the 22nd micro urea as can be known 16 o'clock on the 19th July from above result has reduced to very low---1mg/L, it all is because diamine disturbs the incorrect analysis data that cause that the auxilliary pot feedwater urea in 20 to 22 July is analyzed data, owing to there is not correct analytical approach, measure auxilliary pot feedwater micro urea concentration value exactly, instructed production mistakenly, cause a large amount of auxilliary pot feedwater wastes and environmental pollution (auxilliary pot is added with diamine in feeding water and liquefied ammonia causes environmental pollution), caused than large economy to company and lost.
Claims (5)
1. eliminate diamine to measuring the method that micro urea disturbs in the boiler feed water, it is characterized in that this method is as screening agent with iodine and sodium thiosulfate, in measuring boiler feed water during micro urea, in the boiler feed water water sample, add iodine solution earlier, after allowing iodine and diamine react completely, add hypo solution again and remove unnecessary iodine, drip, can eliminate diamine and disturb to colourless.
2. the method for claim 1 is characterized in that described method is applicable to that the diamine amount is less than the situation of 50mg/L in the boiler feed water water sample.
3. the method for claim 1 is characterized in that the iodine solution that adds in the described method is the iodine solution of 0.01mol/L.
4. the method for claim 1 is characterized in that the time that iodine and diamine react completely in the described method is 18min.
5. the method for claim 1 is characterized in that the hypo solution concentration that described method adds is 0.005mol/L.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910102822A CN101696939A (en) | 2009-10-26 | 2009-10-26 | Method for eliminating interference in measurement of micro urea in boiler feed water from diamine |
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|---|---|---|---|
| CN200910102822A CN101696939A (en) | 2009-10-26 | 2009-10-26 | Method for eliminating interference in measurement of micro urea in boiler feed water from diamine |
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|---|---|
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1439874A (en) * | 2002-02-22 | 2003-09-03 | 东洋工程株式会社 | Method and device for determining urea concentration |
| CN101093206A (en) * | 2006-06-22 | 2007-12-26 | 华东电力试验研究院有限公司 | Method of online testing and controlling content of chloridion in boiler water |
-
2009
- 2009-10-26 CN CN200910102822A patent/CN101696939A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1439874A (en) * | 2002-02-22 | 2003-09-03 | 东洋工程株式会社 | Method and device for determining urea concentration |
| CN101093206A (en) * | 2006-06-22 | 2007-12-26 | 华东电力试验研究院有限公司 | Method of online testing and controlling content of chloridion in boiler water |
Non-Patent Citations (1)
| Title |
|---|
| 陈录华: "对二甲氨基苯甲醛法测定常量尿素", 《大氮肥》 * |
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Application publication date: 20100421 |