On-line measurement method and device for total iron in power station water vapor

Abstract

The present invention relates to the technical field of test and detection, and particularly to an on-line measurement method and device for total iron in power station water vapor. A catalytic reagent is added to the water sample to be measured and acts through an ultraviolet light oxidizer, so as to completely convert the colloidal iron in the water sample into ferric ions. The dissolution and conversion of the colloidal iron are completed without adding acid throughout the process. Since no acid is added during the process of converting the whole colloidal iron into dissolved iron, only a chromogenic reagent needs to be added to accurately measure the total iron content in the water sample, and it is also easier to realize the on-line measurement of total iron in the water sample. When the total iron content in the water sample is less than 10 μg / L, the water sample enters the concentration system for concentration and then optical measurement, so that the low-concentration total iron in the water sample can also be accurately measured. This measurement method can automatically measure the total content in the water sample on-line, avoid manual sampling and detection, can monitor the total iron in the water sample in real time, and has a lower detection limit and more accurate detection results, which is beneficial to the adjustment of the water condition during the start-up and shutdown stages of the power station.

Description

Technical Field

[0001] The present invention relates to the technical field of test and detection, and particularly relates to a method and device for on-line measurement of total iron in power station water vapor. Background Art

[0002] On-line monitoring of total iron in power station water vapor is a major problem. Currently, when detecting total iron in power station water vapor, since most of the iron in power station water vapor exists in the form of colloidal iron, it is necessary to first convert the colloidal iron into dissolved iron before measurement. Generally, strong acid and oxidant are added when taking water samples, and then steamed to make the colloidal iron completely converted into dissolved iron, and then measured by atomic absorption method or o-phenanthroline spectrophotometry to finally obtain the accurate content of total iron. However, since strong acid needs to be added and steaming is required to convert colloidal iron into dissolved iron before detection, and concentrated ammonia water needs to be added to adjust the pH of the water sample converted into dissolved iron before measurement, the steps are complex, time-consuming, the amount of added ammonia water is large and uncertain, making it impossible to realize on-line monitoring of total iron in power station water vapor; and in the conventional measurement process, the workload of chemical analysis and detection is large and time-consuming. Especially when the unit is shut down and started up, since the colloidal iron cannot be quickly converted into dissolved iron, the measurement result of total iron is seriously lagged, and the content of total iron in water cannot be detected in time to guide the adjustment of water conditions, which is not conducive to energy conservation and consumption reduction of the power station. Summary of the Invention

[0003] The purpose of the present invention is to provide a method and device for on-line measurement of total iron in power station water vapor, which is used to realize on-line accurate measurement of total iron in water vapor during the operation of the power station without adding acid.

[0004] The technical solution for solving the problems of the present invention:

[0005] A method for on-line measurement of total iron in power station water vapor, characterized by comprising the following steps:

[0006] 1) Continuously inject the water sample containing colloidal iron into the overflow cup;

[0007] 2) After the water sample flows out of the overflow cup, it flows into the first three-way valve under the pressure of the pump, and at the same time, a catalytic reagent is added to the first three-way valve to be mixed with the water sample;

[0008] 3) After the water sample is mixed with the catalytic reagent, it flows into the ultraviolet light oxidizer, and at this time, the colloidal iron in the water sample is converted into dissolved iron under the action of the catalytic reagent;

[0009] 4) After the colloidal iron in the water sample is converted into dissolved iron, it sequentially passes through the second three-way valve and the third three-way valve and enters the optical sensing system;

[0010] 5) Add reagent A and reagent B to the optical sensing system;

[0011] 6) Dissolved iron completes an optical reaction in the optical sensing system through the action of reagent A and reagent B, and the optical sensing system transmits the measurement signal for measuring the iron content to the data processing system for data processing;

[0012] 7) The data processing system calculates the total iron content in the water sample based on the received measurement signal. When the measurement result of the total iron content is greater than 10 μg / L, the data processing system transmits a signal to the optical sensing system to discharge the water sample that has been measured inside the optical sensing system and perform the next water sample measurement;

[0013] 8) When the total iron content in the water sample calculated by the data processing system is less than 10 μg / L, the data processing system transmits a signal to the optical sensing system to discharge the water sample that has been measured inside the optical sensing system and perform the next step of operation;

[0014] 9) Resample and repeat steps 1) - 3), and let the obtained dissolved iron flow into the concentration system through the second three-way valve for concentration treatment;

[0015] 10) The dissolved iron after concentration treatment enters the optical sensing system through the third three-way valve, and then repeat the operations in steps 5) and 6);

[0016] 11) The data processing system calculates the total iron content of the water sample based on the concentration multiple of the concentration system and the signal measured by the optical sensing system, and transmits a signal to the optical sensing system to discharge the measured water sample and perform the next water sample measurement.

[0017] Further defined, the catalytic reagent in step 2) includes persulfate as (NH 4 ) 2 S 2 O 8 、NH 4 Ac, NH 4 NO 3 and primary reagent water.

[0018] Further defined, the mass percentage of (NH 4 ) 2 S 2 O 8 : NH 4 Ac: NH 4 NO 3 : primary reagent water is 4:2:4:90.

[0019] Further defined, in step 3), under the catalytic oxidation of the catalytic reagent, the ultraviolet light oxidizer realizes the on-line conversion of colloidal iron to dissolved iron in the water sample; wherein the water sample flows into the ultraviolet light oxidizer at a flow rate of 1 - 10 mL / min.

[0020] Further defined, in step 3), the power of the ultraviolet light oxidizer is 30-100 w; the outlet water temperature of the ultraviolet light oxidizer is 35-50 °C, and the water sample flow volume of the ultraviolet light oxidizer is 5 mL-10 mL.

[0021] Further defined, step 5) includes the following steps:

[0022] 5.1) Add reagent A to the water sample entering the optical sensing system, where reagent A is hydroxylamine hydrochloride with a concentration of 2%-5%;

[0023] 5.2) Add reagent B, and reagent B is a mixed solution of phenanthroline and acetic acid-sodium acetate.

[0024] Further defined, step 6) includes the following steps:

[0025] 6.1) Stir the water sample added with reagent A and reagent B at a constant temperature until it is uniform;

[0026] 6.2) Measure the optical signal of the total iron content in the water sample at a wavelength of 420-450 nm and transmit the measurement signal to the data processing system.

[0027] Further defined, reagent B is a solution prepared by mixing 0.1% phenanthroline and 5% acetic acid-sodium acetate solution in a volume ratio of 3:2.

[0028] Based on the device for the on-line measurement method of total iron in power station water vapor described above, it is characterized in that it includes an overflow cup, a pump, a first three-way valve, an ultraviolet light oxidizer, a second three-way valve, a third three-way valve and an optical sensing system connected in sequence, and also includes a catalytic reagent storage tank communicated with the first three-way valve, a concentration system communicated with the second three-way valve and the third three-way valve respectively, a reagent A storage tank communicated with the optical sensing system, a reagent B storage tank communicated with the optical sensing system and a data processing system signal-connected with the optical sensing system.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1) During the process of converting colloidal iron in total iron into dissolved iron, no acid needs to be added, and adding a catalytic reagent can assist in completing the dissolution and conversion of colloidal iron;

[0031] 2) During the process of converting colloidal iron in total iron into dissolved iron, no cooking is required, and the water sample flowing through the ultraviolet light oxidizer can complete the dissolution and conversion of colloidal iron, enabling accurate on-line measurement of total iron;

[0032] 3) During the process of converting colloidal iron in total iron into dissolved iron, no acid needs to be added, so there is no need to adjust the pH with concentrated ammonia water subsequently, greatly reducing the measurement steps and the amount of reagent added;

[0033] 4) The detection limit of total iron in power plant water vapor can be reduced to 0.5 μg / L through the concentration system, enabling accurate online measurement of total iron in the range of (0.5 - 1000) μg / L.

[0034] 5) The measurement process is green and environmentally friendly, with a high degree of intelligence. Description of the Drawings

[0035] Figure 1 It is a schematic structural diagram of the device of the present invention;

[0036] 1 - Overflow cup; 2 - Pump; 3 - First three - way valve; 4 - Catalytic reagent storage tank; 5 - Ultraviolet photo - oxidizer; 6 - Concentration system; 7 - Second three - way valve; 8 - Third three - way valve; 9 - Reagent A storage tank; 10 - Reagent B storage tank; 11 - Optical sensing system; 12 - Data processing system. Detailed Embodiments

[0037] The present invention will be further described below.

[0038] Example 1

[0039] Reference Figure 1 , this example provides an online measurement method for total iron in power plant water vapor, which can measure the total iron content in the range of 0.5 - 1000 μg / L. The method includes the following steps:

[0040] 1) Continuously inject the water sample containing colloidal iron into the overflow cup 1;

[0041] Among them, the main form of iron in the water sample is colloidal iron.

[0042] 2) After the water sample flows out of the overflow cup 1, it flows into the first three - way valve 3 under the pressure of the pump 2, and at the same time, a catalytic reagent is added to the water sample in the first three - way valve 3 for mixing;

[0043] Specifically, the catalyst includes persulfate (NH 4 ) 2 S 2 O 8 , NH 4 Ac, NH 4 NO 3 , primary reagent water, and the mass percentage of (NH 4 ) 2 S 2 O 8 : NH 4 Ac: NH 4 NO 3 : primary reagent water is 4 - 5: 2 - 5: 4 - 10: 80 - 90, and its preferred mass percentage is 4: 2: 4: 90.

[0044] 3) After the water sample is mixed with the catalytic agent, it flows into the ultraviolet light oxidizer 5. At this time, the colloidal iron in the water sample is converted into dissolved iron under the action of the catalytic agent;

[0045] Specifically, under the action of catalytic oxidation by the catalytic agent, the ultraviolet light oxidizer 5 realizes the on-line conversion of colloidal iron to dissolved iron in the water sample. Among them, the water sample flows into the ultraviolet light oxidizer 5 at a flow rate of 1-10 mL / min, and the power of the ultraviolet light oxidizer 5 is 30-100 w. The outlet water temperature of the ultraviolet light oxidizer 5 is 35-50 °C, and the water sample flow volume of the ultraviolet light oxidizer 5 is 5 mL-10 mL.

[0046] 4) After the colloidal iron in the water sample is converted into dissolved iron, it sequentially passes through the second three-way valve 7 and the third three-way valve 8 and enters the optical sensing system 11;

[0047] At this time, the colloidal iron in the water sample is converted into dissolved ferric iron, and there is also a catalytic agent at the same time. However, the catalytic agent will not affect the measurement of the optical sensing system 11 at this time.

[0048] 5) Add reagent A and reagent B to the optical sensing system 11;

[0049] Specifically, it includes the following steps:

[0050] 5.1) Add reagent A to the water sample entering the optical sensing system 11, where reagent A is hydroxylamine hydrochloride with a concentration of 2%-5%;

[0051] 5.2) Add reagent B. Reagent B is a mixed solution of 0.1% o-phenanthroline and 5% acetic acid-sodium acetate solution. The mixing ratio of 0.1% o-phenanthroline solution to 5% acetic acid-sodium acetate is preferably 3:2 by volume. Reagent A and reagent B are chromogenic reagents.

[0052] 6) The dissolved iron completes an optical reaction in the optical sensing system 11 under the action of reagent A and reagent B. The optical sensing system 11 transmits the measurement signal of the iron content to the data processing system 12 for data processing;

[0053] Specifically, it includes the following steps:

[0054] 6.1) Keep the water sample added with reagent A and reagent B at a constant temperature and stir until it is uniform;

[0055] 6.2) Measure the optical signal of the total iron content in the water sample at a wavelength of 420-450 nm and transmit the measurement signal to the data processing system 12.

[0056] 7) The data processing system 12 calculates the total iron content in the water sample based on the received measurement signal. When the measurement result of the total iron content is greater than 10 μg / L, the data processing system 12 sends a signal to the optical sensing system 11 to discharge the water sample that has been measured inside the optical sensing system 11 and conduct the next water sample measurement;

[0057] 8) When the total iron content in the water sample calculated by the data processing system 12 is less than 10 μg / L, the data processing system 12 sends a signal to the optical sensing system 11 to discharge the water sample that has been measured inside the optical sensing system 11 and proceed to the next step;

[0058] 9) Resample and repeat steps 1) - 3), and let the obtained dissolved iron flow into the concentration system 6 through the second three-way valve 7 for concentration treatment;

[0059] 10) The concentrated dissolved iron then enters the optical sensing system 11 through the third three-way valve 8, and then repeat the operations of steps 5) and 6);

[0060] 11) The data processing system 12 calculates the total iron content of the water sample based on the concentration multiple of the concentration system 6 and the signal measured by the optical sensing system 11, and sends a signal to the optical sensing system to discharge the measured water sample and conduct the next water sample measurement.

[0061] Example 2

[0062] An on-line total iron measurement device for power station water vapor provided in this example includes an overflow cup 1, a pump 2, a first three-way valve 3, an ultraviolet light oxidizer 5, a second three-way valve 7, a third three-way valve 8, and an optical sensing system 11 connected in sequence. It also includes a catalytic reagent storage tank 4 communicated with the first three-way valve 3, a concentration system 6 communicated with the second three-way valve 7 and the third three-way valve 8 respectively, a reagent A storage tank 9 communicated with the optical sensing system 11, a reagent B storage tank 10 communicated with the optical sensing system 11, and a data processing system 12 signal-connected with the optical sensing system 11.

[0063] Water samples continuously flow into the overflow cup 1. The bottom of the overflow cup 1 is provided with a liquid outlet, and a conduit is connected to the liquid outlet to divert the water samples in the overflow cup 1. The pump 2 is installed on the diversion pipe to make the flow rate of the water samples more stable and controllable. After the water samples flow into the first three-way valve 3, the catalytic agent is added from the catalytic agent storage tank 4 into the first three-way valve 3 for mixing. After mixing, it flows from the first three-way valve 3 into the ultraviolet light oxidizer 5 for reaction, so that the colloidal iron in the water samples is converted into trivalent dissolved iron. Subsequently, the dissolved iron sequentially passes through the second three-way valve 7 and the third three-way valve 8 and enters the optical sensing system 11. Then, the reagent A storage tank 9 and the reagent B storage tank 10 correspondingly add reagent A and reagent B into the optical sensing system 11. After being stirred at a constant temperature with the dissolved iron, the total iron content is measured. Finally, the measurement result is sent to the data processing system 12 through the measurement signal. When the measurement result is greater than the preset value, for example, 10 μg / L, the water samples in the optical sensing system 11 are discharged, and then the next total iron content measurement is carried out to continuously obtain the total iron content in the water samples.

[0064] When the measurement result is less than the preset value, that is, less than 10 μg / L, after the optical sensing system 11 discharges all the water samples inside it, the dissolved iron flows through the concentration system 6 for concentration after flowing from the ultraviolet light oxidizer 5 into the second three-way valve 7 and then flows into the optical sensing system 11 from the third three-way valve 8. When the concentration system 6 is concentrating, the concentration multiple can be adjusted in a timely manner. The default concentration ratio is 10 times. After reagent A and reagent B are added to the optical sensing system 11 and stirred at a constant temperature until uniform, the total iron content is continuously measured, and the measurement signal is transmitted to the data processing system 12. The water samples in the optical sensing system 11 are discharged, and the system measures another group of water samples. At this time, it is still a direct measurement. If the measurement result is less than 10 μg / L, then it is measured after concentration.

[0065] Ultraviolet light oxidizer 5. In the ultraviolet oxidizer, the water samples with the catalytic agent added, the colloidal iron in the water is completely converted into dissolved iron; optical sensing system 11. Since no acid is added during the whole process of converting colloidal iron into dissolved iron, there is no need to add ammonia water to adjust the pH in the dissolved water samples. Only adding reagent A and reagent B can accurately measure the total iron in the water samples from 10 to 1000 μg / L, and it is also easier to realize the on-line measurement of the total iron in the water samples; concentration system 6, which can concentrate Fe at 0.5 μg / L by more than 20 times under normal temperature and pressure, so that the total iron below 0.5 μg / L in the water samples can be accurately measured. 3+ Concentrate more than 20 times, so that the total iron below 0.5 μg / L in the water samples can be accurately measured.

Claims

1. An on-line measurement method for total iron in power station water vapor, characterized in that, it includes the following steps: 1) Continuously inject the water sample containing colloidal iron into the overflow cup (1); 2) After the water sample flows out of the overflow cup (1), it flows into the first three-way valve (3) under the pressure of the pump (2), and at the same time, a catalytic reagent is added to the first three-way valve (3) to mix with the water sample; 3) After the water sample is mixed with the catalytic reagent, it flows into the ultraviolet light oxidizer (5). At this time, the colloidal iron in the water sample is converted into dissolved iron. The catalytic reagent includes persulfate as (NH 4 ) 2 S 2 O 8 , NH 4 Ac, NH 4 NO 3 and primary reagent water; 4) After the colloidal iron in the water sample is converted into dissolved iron, it passes through the second three-way valve (7) and the third three-way valve (8) in sequence and enters the optical sensing system (11); 5) Add reagent A and reagent B to the optical sensing system (11); 6) The dissolved iron completes an optical reaction in the optical sensing system (11) under the action of reagent A and reagent B, and the optical sensing system (11) transmits the measurement signal for measuring the iron content to the data processing system (12) for data processing; 7) The data processing system (12) calculates the content of total iron in the water sample through the received measurement signal. When the measurement result of the total iron content is greater than 10 μg / L, the data processing system (12) sends a signal to the optical sensing system (11) to discharge the water sample that has completed the measurement inside the optical sensing system (11) and conduct the next water sample measurement; 8) When the content of total iron in the water sample calculated by the data processing system (12) is less than 10 μg / L, the data processing system (12) sends a signal to the optical sensing system (11) to discharge the water sample that has completed the measurement inside the optical sensing system (11) and conduct the next step of operation; 9) Resample and repeat steps 1) to 3), and let the obtained dissolved iron flow into the concentration system (6) through the second three-way valve (7) for concentration treatment; 10) The concentrated dissolved iron then enters the optical sensing system (11) through the third three-way valve (8), and then repeat the operations of steps 5) and 6); 11) The data processing system (12) calculates the content of total iron in the water sample according to the concentration multiple of the concentration system (6) and the signal measured by the optical sensing system (11), and sends a signal to the optical sensing system to discharge the measured water sample and conduct the next water sample measurement.

2. The on-line measurement method for total iron in power station water vapor according to claim 1, characterized in that, The (NH 4 ) 2 S 2 O 8 : NH 4 Ac: NH 4 NO 3 : The mass percentage of primary reagent water is 4:2:4:

90.

3. The on-line measurement method for total iron in power station water vapor according to claim 2, characterized in that, In step 3), under the catalytic oxidation of the catalytic reagent, the ultraviolet light oxidizer (5) realizes the on-line conversion of colloidal iron to dissolved iron in the water sample; wherein the water sample flows into the ultraviolet light oxidizer (5) at a flow rate of 1-10 mL / min.

4. The on-line measurement method for total iron in power station water vapor according to claim 3, characterized in that, The power of the ultraviolet light oxidizer (5) in step 3) is 30-100 w; the outlet water temperature of the ultraviolet light oxidizer (5) is 35-50 °C, and the water sample flow volume of the ultraviolet light oxidizer (5) is 5 mL-10 mL.

5. The on-line measurement method for total iron in power station water vapor according to claim 4, characterized in that, Step 5) includes the following steps: 5.1) Add reagent A to the water sample entering the optical sensing system (11), where reagent A is hydroxylamine hydrochloride with a concentration of 2% - 5%. 5.2) Add reagent B, which is a mixed solution of phenanthroline and acetic acid - sodium acetate.

6. The on - line measurement method for total iron in power station water vapor according to claim 5,[[]]END]] characterized in that,[[]]END]] the step 6) includes the following steps:[[]]END]] 6.1) Keep the water sample added with reagent A and reagent B at a constant temperature and stir until it is uniform.[[]]END]] 6.2) Measure the optical signal of the total iron content in the water sample at a wavelength of 420 - 450 nm and transmit the measured signal to the data processing system (12).

7. The on - line measurement method for total iron in power station water vapor according to claim 5,[[]]END]] characterized in that,[[]]END]] reagent B is a solution prepared by mixing 0.1% phenanthroline and 5% acetic acid - sodium acetate solution in a volume ratio of 3:2.[[]]END]] 8. The device based on the on - line measurement method for total iron in power station water vapor according to claim 7,[[]]END]] characterized in that,[[]]END]] it includes an overflow cup (1), a pump (2), a first three - way valve (3), an ultraviolet light oxidizer (5), a second three - way valve (7), a third three - way valve (8) and an optical sensing system (11) connected in sequence, and also includes a concentration system (6), a catalytic reagent storage tank (4) communicated with the first three - way valve (3), a reagent A storage tank (9) communicated with the optical sensing system (11), a reagent B storage tank (10) communicated with the optical sensing system (11) and a data processing system (12) signal - connected to the optical sensing system (11), and the concentration system (6) is communicated with the second three - way valve (7) and the third three - way valve (8).

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