Method for the determination of film-forming amines

Abstract

Within a method for the determination of film-forming amines in liquids by adding a reacting agent with the amine to form a colored complex to be measured by photometric method for the reaction the pH of the liquid mixture is lowered by using hydrochloric acid.

Claims

1. Method for the determination of film-forming amines in liquids by adding a reacting agent having a PK.sub.a value to the amine to form a colored complex to be measured by photometric method, characterized by adding hydrochloric acid to lower the pH value of the liquid solution to a value <2.3 and characterized in that the reacting agent is a component of the Xanthene Group according to the following general formula: ##STR00002## wherein, R.sup.1=H or a halogen, and R.sup.2=H or a halogen.

2. Method according to claim 1, characterized in that the determination takes place in an aqueous solution having a pH value that is lower than the pK.sub.a value of the reacting agent to form the colored complex with the film-forming amine.

3. Method according to claim 1, characterized in that the film-forming amine is of the following general formula:
R.sup.1(NHR.sup.2).sub.nNH.sub.2 with R.sup.1: non-branched alkyl chain with 12-18 C-Atoms, R.sup.2: short chained alkyl chain with 1 to 4 C-Atoms, and n: natural number or integer between 0 and 7.

4. Method according to claim 1, characterized in that the reacting agent is selected from the group consisting of fluorescein, Bengal rose, Eosin and Erythrosine.

5. Method according to claim 1, characterized in that an acid resistant detergent is used to prevent the formation of a deposition.

6. Method according to claim 1, characterized in that a time in which the amine and the reacting agent react before the photometric measuring is in the range of 4 seconds to 10 minutes.

7. Method according to claim 1, characterized in that a temperature at which the amine and the reacting reagent react is in the range of 15 to 40 C.

8. Use of the method according to claim 1 for the determination of film-forming amines in feed-water or water steam cycles of power plants characterized in that into circular flow or a test sample containing the film-forming amine a first reacting agent is added to form a colored complex and approximately at the same time a solution containing hydrochloric acid is added, the reaction mixture is continued to a photometric measuring device or measuring cell, in which the measuring of the colored complex is executed with or without interruption of the flow.

9. Use according to claim 8, characterized in that while or after adding and mixing of the first reacting agent and the solution containing hydrochloric acid into the circular flow or the test sample the flow is interrupted and after a certain reaction time the flow of the reaction mixture is continued to the photometric measuring device, where the measuring takes place.

10. Use of the method according to claim 1 for the determination of film-forming amines in feed-water or water steam cycles of power plants characterized in that the circular flow or test sample is introduced into a photometric measuring device, the flow being interrupted, afterwards a first reacting agent containing the reacting agent forming a colored complex with the amine is added into the photometric measuring device and subsequently a second reacting agent, containing at least hydrochloric acid, is introduced into the photometric measuring device, where the reaction takes place and finally the measuring of the formed colored complex is executed.

Description

(1) With reference to the attached figures, three examples of the execution of the method according to the present invention are described:

(2) FIG. 1 shows a direct flow injection method, where no interruption of the inlet probe takes place when mixing with reacting agents and following measurement in the photometric device,

(3) FIG. 2 shows a similar test arrangement as FIG. 1, but with interruption of the inlet probe when mixing with reacting agents, and

(4) FIG. 3 shows the measuring method, where the mixing procedure of the liquid solution containing the film-forming amine with the reacting agents takes place within the photometric device.

(5) FIG. 1 shows a first embodiment of the inventive method in the sense of a principal representation. Through a first line 1, the inlet of a probe of the feed-water or water-steam cycle containing the film-forming amine is introduced into a mixing chamber 3. The first reacting agent, which is a Xanthene dye stuff diluted in water, is added via inlet 5 into the mixing chamber, at the same time with the second reacting agent via inlet 7, which is a hydrochloric acid solution to lower the pH value to the total solution to a value of lower of the pK.sub.a value of the Xanthene dye stuff.

(6) The adding of the two reacting agents is carried out at the same time with e.g. an adding velocity of approx. 3.5 ml/min during 10 sec. Afterwards the reacting mixture is flowing through a conduit or connecting passage 9, which can be e.g. a so-called reacting spiral to the photometric measuring device 13, where the measuring is executed. The reaction mixture requires only a few seconds to flow from the mixing chamber to the photometric measuring device. The measuring is executed with a wave-length in a range between 400 and 560 nm dependent upon the Xanthene dye stuff being used.

(7) Within the following Table 1 various possible Xanthene dye stuff reacting agents are listed in the sense of examples, which can be used to determine the concentration of film-forming amines. In Table 1 also the wave-length is indicated, at which the photometric detection is made in dependence of the used dye stuff as reacting agent. The great advantage of the present invention is that the photometric detection can be made in a simple photometric measuring device using an ordinary LED source.

(8) TABLE-US-00001 Name R.sub.1 R.sub.2 .sub.max [nm] Bengal Rose I CI 570 Eosin Br H 540 Erythrosin I H 500

(9) FIG. 2 shows a second embodiment of the inventive method, again in the sense of a principal representation. In principle, a similar method as described with reference to FIG. 1 is executed with the difference that after the mixture is introduced via the conduit 9 into the photometric measuring cell, valve 11 is closed. So the reacting mixture remains within the photometric measuring device 13. After a certain reaction time, which is dependent upon the doses of the reacting agents and furthermore from the pH values as well as from the temperature, again the measuring is executed within the photometric measuring device 13.

(10) After measuring the concentration of the film-forming amine, the valve 11 is opened again and the aqueous feed-water can circulate.

(11) In FIG. 3 a method according to a batch measurement is shown, where the mixing between the various reacting agents with the feed-water takes place within the photometric device 13 itself. The inlet of the feed-water or water steam cycle 1 is introduced into the photometric device. Before starting the measuring process the inlet flow is interrupted by the valve 17. As a result the test sample of the water cycle remains stationary within the photometric device. First the first reacting agent, which means the Xanthene dye stuff, is pumped via inlet 5 using a pump 21 into the photometric device 13. After adding the first reacting agent the valve 19 switches to the second reacting agent, which is hydrochloric acid. Again the adding is effected via inlet 7 by using the pump 21. After the addition of the two reacting agents a reacting time of approx. 13 sec takes place. Afterwards the measuring is executed and finally valve 17 again is opened and the test solution is removed via the outlet 15.

(12) Example 1:

(13) Using the embodiment as shown in FIG. 1, the following practical example has been executed:

(14) Flow rate with the first inlet line: 80-90 ml/min

(15) Temperature of the inlet flow: 20-35 C.

(16) pH-value of the inlet flow varies between 7.5 and 10.5 (mixture of feed-water, film-forming amine and Ammonia, Ethanolamine and Morpholine as alkalinizing additives)

(17) As first reacting agent: 1.4 g Eosin disodium salt (purity >85%) diluted in 2000 g totally desalinated water combined with 3 g of a wetting agent (non-ionic tenside).

(18) Second reacting agent: Recipe for the production of a 2 l buffering solution: 1270 ml of 2.5 M Glycin mixed with 730 ml 2.5 M HCl.

(19) Sequence of the measuring process:

(20) Minimal measuring interval: 1 min.

(21) Measuring range: 0.05 ppm-5 ppm

(22) Example 2:

(23) Using the embodiment as shown in FIG. 2 the following practical example has been executed:

(24) Flow rate of the first inlet line 1: 80-90 ml/min.

(25) Temperature of inlet flow: 20-35 C.

(26) pH value of inlet flow between 7.5 and 10.5 (mixture of feed water, film-forming amine and Ammonia, Ethanolamine and Morpholine as alkalinizing additives)

(27) Reacting time (closure of valve): 7 min.

(28) First Reacting Agent: 1.4 g Eosin disodium salt (purity >85% diluted in 2000 g totally desalinated water together with 3 g of a wetting agent (non-ionic tenside)

(29) Second reacting agent: 5 M HCl

(30) Sequence of the measuring process:

(31) Minimal interval of measuring: 10 min.

(32) Measuring range: 0.3 ppm-5 ppm.

(33) Example 3:

(34) Using the third embodiment the following practical example has been executed:

(35) Flow of the inlet 1: 80-90 ml/min

(36) Temperature of inlet: 20-35 C.

(37) pH: 7.5-10.5 (mixture additionally containing Ammonia, Ethanolamine and Morpholine as alkalization additives)

(38) Reacting time: 30 sec after adding the first reacting agent 5

(39) First reacting agent: 1.4 g Eosin disodium salt (purity >85%) diluted in 2000 g totally desalinated water together with 3 g of a wetting agent (non-ionic tenside)

(40) Second reacting agent: Recipe for the production of a 2 l buffering solution: 500 ml 2.5 M KCl are mixed with 130 ml 2.5 M HCl and filled up to 2 L with totally desalinated water (HCl/KCl buffering system)

(41) Sequence of measuring:

(42) Minimum interval of measuring: 5 min.

(43) Measuring range: 0.1 ppm-5 ppm

(44) Further to the described methods, it is of course possible to add an acid resistant detergent, which prevents the forming of a deposition, e.g. within the mixing chamber.

(45) The methods as described with reference to FIG. 1 to FIG. 3 are only examples for the better understanding of the present invention. Of course different designs of the method are possible; important is the reduction of the pH value of the mixture of the feed-water solution with the film-forming amines with the reacting agent, forming a colored complex with the amines to a pK.sub.a value of the dye stuff, preferably <2.3.