A method for rapid switching of COD range

Abstract

The application discloses a COD fast switching range method, judges whether the current range is 0-amg / L, when it is 0-amg / L, judges whether S2>K1*S1 is established, when S2>K1*S1 is not established, continues to complete the measurement; when S2>K1*S1 is established, switches to 0-bmg / L, completes the measurement process; when it is not 0-amg / L, judges whether S2<K2*S1 is established, when S2<K2*S1 is not established, continues to complete the measurement; when S2<K2*S1 is established, switches to 0-amg / L, completes the measurement process; wherein, K1 is a number greater than 1 and less than 2, K2 is a number less than 1 and greater than 0.8. The application has the advantages of short COD range switching measurement time, high COD value measurement efficiency, reduced heating energy consumption, reduced heating wire use loss and reduced light source use loss.

Description

Technical Field

[0001] The present invention belongs to the technical field of COD measurement, and specifically relates to a method for fast range switching of COD. Background Art

[0002] In some on-site detection scenarios, the COD value of water samples detected at different time periods may vary. To measure the COD value more accurately, it is necessary to select an appropriate range for measurement according to the COD level. However, since different ranges differ in the injection volume of water sample, whether the water sample is diluted or not, and the number of dilutions, for a water sample with unknown COD concentration, it is normally required to first measure the approximate concentration with a certain range. If the measured concentration falls within the range, there is no need to switch the range. If it exceeds the measurement range, it is necessary to switch to the corresponding range, adjust the injection times and dilution amount to re-measure the water sample. For COD instruments that measure COD by the potassium dichromate method, the entire digestion process takes at least 15 minutes, and other procedures such as sample addition, liquid drainage, cleaning, and temperature reduction make the overall process take at least about 40 minutes. In this case, if range switching is required, twice the time of the normal measurement process will be needed. As a result, the time for COD measurement with range switching is long, the efficiency of COD value measurement is low, the energy consumption for heating is high, the service loss of the heating wire is large, and the service loss of the light source is large. Summary of the Invention

[0003] Aiming at the above deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a method for fast range switching of COD, which features short time for COD measurement with range switching, high efficiency of COD value measurement, reduced energy consumption for heating, reduced service loss of the heating wire, and reduced service loss of the light source.

[0004] To solve the above technical problem, the technical solution adopted by the present invention is: a method for fast range switching of COD, comprising the following steps:

[0005] Step 1: Select a standard solution with concentration a for measurement, continuously take a plurality of signal values from the measurement signals after a mixing time t, and calculate the variance S of the plurality of signal values a ; Assume that the automatic ranges of the currently used COD rapid analyzer are 0-a mg / L and 0-b mg / L respectively, where a < b, and a is taken as the boundary value of the two ranges;

[0006] Step 2: Compare the variance S a with the empirical variance S 标 , when S a > S 标 , update the plurality of signal values, continue to take the next signal value, and continue to calculate the variance S of the plurality of signal values a ;

[0007] Step 3: Compare variances S a With empirical variance S 标 The size of S a Still greater than S 标 Then, continue repeating steps one through three above until S... a Less than S 标 Or, the number of repetitions reaches the preset number of repetitions N1;

[0008] Step 4: Take the average of the above steps to obtain S1;

[0009] Step 5: Select a water sample with an unknown concentration of m for measurement. After a mixing time t, continuously collect multiple signal values ​​and calculate the variance S of the multiple signal values. m ;

[0010] Step 6: Compare the variance S m With empirical variance S 标 The size of S m >S 标 At this time, multiple signal values ​​are updated, the next signal value is taken, and S is calculated again. m1 To S m10 variance S m ;

[0011] Step 7: Compare variances S m With empirical variance S 标 The size of S m Still greater than S 标 Continue repeating the above steps until S m Less than S 标 Or, the number of repetitions reaches the preset number of repetitions N2;

[0012] Step 8: Take the average of the multiple signal values ​​after the final stop of the above steps to obtain S2;

[0013] Step 9: Determine whether the current range is 0-a mg / L. When the current range is 0-a mg / L, determine whether S2>K1*S1 is true. If S2>K1*S1 is not true, continue to run to complete the current measurement; if S2>K1*S1 is true, immediately stop the current measurement process, drain the liquid inside, clean the entire pipeline with distilled water, then immediately switch to 0-b mg / L to complete one measurement process. When the current range is not 0-a mg / L, determine whether S2<K2*S1 is true. If S2<K2*S1 is not true, continue to run to complete the current measurement; if S2<K2*S1 is true, immediately stop the current measurement process, drain the liquid inside, clean the entire pipeline with distilled water, then immediately switch to 0-a mg / L to complete one measurement process. Wherein K1 is a number greater than 1 and less than 2, and K2 is a number less than 1 and greater than 0.8.

[0014] In the above COD rapid range switching method, 10 signal values are continuously collected in step 1, that is, S a1 , S a2 , ..., S a10 , and the variance S of S a1 to S a10 is calculated a ;

[0015] In step 2, when S a >S 标 , take S a1 =S a2 , S a2 =S a3 , ..., S a9 =S a10 , S a10 ;

[0016] In step 4, the signal values S obtained after the above steps are finally stopped are taken a1 , S a2 , ..., S a10 are averaged to obtain S1;

[0017] In step 5, 10 signal values are continuously collected, that is, S m1 , S m2 , ..., S m10 , and the variance S of S m1 to S m10 is calculated m ;

[0018] In step 6, when S m >S 标 , take S m1 =S m2 , S m2 =S m3 , ..., Sm9 =S m10 S m10 ;

[0019] In step eight, take the signal value S after finally stopping the above steps. m1 S m2 ... S m10 The average value is S2.

[0020] The above-described method for rapid COD range switching involves repeating steps one through three in step three, with the termination condition being the number of repetitions reaching a preset number of repetitions N1.

[0021] In the above-mentioned method for rapid switching of COD range, the preset number of repetitions N1 is 10.

[0022] In the above-described method for rapid COD range switching, step seven continues to repeat the above steps until the number of repetitions reaches the preset number of repetitions N2.

[0023] In the above-mentioned method for rapid switching of COD range, the preset number of repetitions N2 is 10.

[0024] In the above-mentioned method for rapid switching of COD range, the value of K1 is 1.1.

[0025] In the above-mentioned method for rapid switching of COD range, the value of K2 is 0.9.

[0026] In the above-mentioned method for rapid switching of COD range, the time t is 1 minute.

[0027] Compared with existing technologies, this invention has the following advantages: By comparing the COD signal value S1 at the automatic range dividing point with the signal value S2 of the current COD value, this invention can quickly determine which range is suitable for the current COD value. If the current range is suitable, the measurement can continue; otherwise, the measurement in the current range is stopped and another range is switched for measurement. Compared with the previous method that required a complete range switching process, this method can omit the lengthy digestion process and the high-temperature cooling process, enabling a faster automatic range switching process. The range switching time for COD measurement is short, the COD value measurement efficiency is high, and the energy consumption for heating, the wear and tear on the heating wire, and the wear and tear on the light source are reduced.

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0029] Figure 1 This is a flowchart of the method of the present invention. Detailed Description of the Embodiments

[0030] As shown Figure 1 in the figure, the method for rapidly switching the range of the COD rapid measuring instrument of the present invention comprises the following steps:

[0031] Step 1: Select a standard solution with concentration a for measurement, continuously take a plurality of signal values from the measurement signals after a mixing time t, and calculate the variance S of the plurality of signal values a ; assuming that the automatic ranges of the currently used COD rapid measuring instrument are 0-a mg / L and 0-b mg / L respectively, where a < b, a is taken as the boundary value of the two ranges;

[0032] In this embodiment, 10 signal values are continuously taken in Step 1, that is, S a1 , S a2 , ..., S a10 , and the variance S of S a1 to S a10 is calculated a ;

[0033] Step 2: Compare the magnitude of the variance S a and the empirical variance S 标 , and when S a > S 标 , update the plurality of signal values, continue to take the next signal value, and continue to calculate the variance S of the plurality of signal values a ;

[0034] In this embodiment, when S a > S 标 in Step 2, S a1 = S a2 , S a2 = S a3 , ..., S a9 = S a10 , S a10 ;

[0035] Step 3: Compare the magnitude of the variance S a and the empirical variance S 标 , and when S a is still greater than S 标 , continue to repeat the above Step 1 to Step 3 until S a is less than S 标 , or the number of repetitions reaches the preset number of repetitions N1;

[0036] In this embodiment, in Step 3, the above Step 1 to Step 3 are continuously repeated, and the termination condition is that the number of repetitions reaches the preset number of repetitions N1.

[0037] In this embodiment, the value of the preset number of repetitions N1 is 10.

[0038] Step 4: Take the average of the above steps to obtain S1;

[0039] In this embodiment, step four involves taking the signal value S after the final cessation of the above steps. a1 S a2 ... S a10 The average value is S1;

[0040] Step 5: Select a water sample with an unknown concentration of m for measurement. After a mixing time t, continuously collect multiple signal values ​​and calculate the variance S of the multiple signal values. m ;

[0041] In this embodiment, step five involves continuously taking 10 signal values, namely S. m1 S m2 ... S m10 Calculate S m1 To S m10 variance S m ;

[0042] Step 6: Compare the variance S m With empirical variance S 标 The size of S m >S 标 At this time, multiple signal values ​​are updated, the next signal value is taken, and S is calculated again. m1 To S m10 variance S m ;

[0043] In this embodiment, in step six, when S m >S 标 When, take S m1 =S m2 S m2 =S m3 S m9 =S m10 S m10 ;

[0044] Step 7: Compare variances S m With empirical variance S 标 The size of S m Still greater than S 标 Continue repeating the above steps until S m Less than S 标 Or, the number of repetitions reaches the preset number of repetitions N2;

[0045] In this embodiment, step seven continues to repeat the above steps, and the termination condition is until the number of repetitions reaches the preset number of repetitions N2.

[0046] In this embodiment, the value of the preset number of repetitions N2 is 10.

[0047] Step 8: averaging a plurality of signal values obtained after the above steps are finally stopped to obtain S2;

[0048] In this embodiment, in Step 8, the signal values S obtained after the above steps are finally stopped m1 , S m2 , ..., S m10 are averaged to obtain S2.

[0049] Step 9: determining whether the current range is 0-a mg / L; when the current range is 0-a mg / L, determining whether S2>K1*S1 is satisfied; when S2>K1*S1 is not satisfied, continuing to run to complete the current measurement; when S2>K1*S1 is satisfied, immediately stopping the current measurement process, discharging the liquid inside and washing the entire pipeline with distilled water, then immediately switching to 0-b mg / L to complete one measurement process; when the current range is not 0-a mg / L, determining whether S2<K2*S1 is satisfied; when S2<K2*S1 is not satisfied, continuing to run to complete the current measurement; when S2<K2*S1 is satisfied, immediately stopping the current measurement process, discharging the liquid inside and washing the entire pipeline with distilled water, then immediately switching to 0-a mg / L to complete one measurement process; where K1 is a number greater than 1 and less than 2, and K2 is a number less than 1 and greater than 0.8.

[0050] In this embodiment, the value of K1 is 1.1. The value of K2 is 0.9.

[0051] In this embodiment, the value of the time t is 1 minute. That is, after all reagents enter the digestion device and are fully mixed, the measurement signal one minute after mixing is taken as the reference signal for judging COD measurement of different water samples and standard solutions.

[0052] According to the curve generated after the previous collection of measurement signals for COD digestion and color development, after all reagents are added, fully mixed and reacted for the same period of time, the signal received by the receiving end of the optical sensor is positively correlated with the final result. This is because the chemical reaction has started after the solutions are mixed, and the received signals have already been differentiated according to different COD concentrations in the water sample. As the temperature rises after the reagents are mixed, the signal value received by the optical sensor gradually changes and stabilizes within a numerical range. In order to quickly determine the approximate range of the currently measured COD value, we select the data at 1 minute after mixing as the judgment reference data. At this time, the organic matter in the water sample has been partially oxidized, and the signals collected from water samples with different COD concentrations already have discrimination. Therefore, to judge the range of the current COD value, it is only necessary to compare the COD signal value S1 at the range demarcation point of the auto-range with the signal value S2 of the current COD value.

[0053] The range switching process in step 9 above can also be explained as: if S2>K1*S1, the large range of 0-b mg / L is selected. If the currently used range is 0-b mg / L, the current measurement is continued; if the currently used range is 0-a mg / L, the measurement process is stopped immediately, the liquid inside is drained and the entire pipeline is cleaned with distilled water, then the range is immediately switched to 0-b mg / L to complete one measurement process. If currently S2<K2*S1, the small range of 0-a mg / L is selected. If the currently used range is 0-a mg / L, the current measurement is continued; if the currently used range is 0-b mg / L, the measurement process is stopped immediately, the liquid inside is drained and the entire pipeline is cleaned with distilled water, then the range is immediately switched to 0-a mg / L to complete one measurement process. If S2<K1*S1 and S2>K2*S1, the current range is continuously used to complete the measurement.

[0054] By comparing the COD signal value S1 at the range demarcation point of the auto-range with the signal value S2 of the current COD value, it is possible to quickly determine which range the current COD value is suitable for. If the current range is applicable, the measurement can be continued; otherwise, the measurement under the current range is stopped and switched to another range for measurement. Compared with the previous process that required a complete range switching procedure, this method can omit the long-time digestion process and the high-temperature cooling process, and can complete the auto-range switching process more quickly.

[0055] Similarly, if the range switching involves more than two ranges, it is only necessary to compare the signal values at 1 minute after mixing at the demarcation points between the multiple ranges with the currently measured signal value, and judge whether it is necessary to switch the range by determining whether the currently measured signal value exceeds or is lower than ten percent of the demarcation point signal.

[0056] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for rapidly switching COD ranges, characterized in that, The method includes the following steps: Step 1: Select a standard solution with concentration a for measurement, continuously collect a plurality of signal values of the measurement signal after a mixing time t, and calculate the variance S of the plurality of signal values a ; Assume that the automatic ranges of the currently used COD rapid measuring instrument are 0-a mg / L and 0-b mg / L respectively, where a < b, and a is taken as the demarcation value of the two ranges; Step 2: Compare variances S a With empirical variance S 标 The size of S a >S 标 At this time, multiple signal values ​​are updated, the next signal value is taken, and the variance S of multiple signal values ​​is calculated again. a ; Step 3: Compare the variance Sa with the empirical variance S_standard. If Sa is still greater than S_standard, repeat steps 2 to 3 above until S_standard is greater than S_standard. a Less than S 标 Or, the number of repetitions reaches the preset number of repetitions N1; Step 4: Take the average of the multiple signal values ​​after the final stop of the above steps to obtain S1; Step 5: Select a water sample with an unknown concentration of m for measurement. After a mixing time t, continuously collect multiple signal values ​​and calculate the variance S of the multiple signal values. m ; Step 6: Compare the variance S m With empirical variance S 标 The size of S m >S 标 At this time, multiple signal values ​​are updated, the next signal value is taken, and the variance S of multiple signal values ​​is calculated again. m ; Step 7: Compare variances S m With empirical variance S 标 The size of S m Still greater than S 标 Then, continue repeating steps six and seven above until S. m Less than S 标 Or, the number of repetitions reaches the preset number of repetitions N2; Step 8: Take the average of the multiple signal values ​​after the final stop of the above steps to obtain S2; Step 9: Determine if the current measurement range is 0-amg / L. If the current measurement range is 0-amg / L, determine if S2 > K1. Does S1 hold true when S2 > K1? If S1 is not true, continue the measurement to complete the current measurement; if S2 > K1 When S1 is established, immediately stop the current measurement process, drain the liquid, and flush the entire pipeline with distilled water. Then immediately switch to 0-bmg / L to complete one measurement cycle. When the current range is not 0-amg / L, determine S2. <K2 Whether S1 is true depends on whether S2 is true. <K2 If S1 is not true, continue the measurement to complete the current measurement; if S2 is not true, continue the measurement to complete the current measurement. <K2 When S1 is established, the current measurement process is immediately stopped, the liquid inside is drained and the entire pipeline is rinsed with distilled water, and then immediately switched to 0-amg / L to complete one measurement process; where K1 is a number greater than 1 and less than 2, and K2 is a number less than 1 and greater than 0.

8.

2. The method for rapid switching of COD range according to claim 1, characterized in that: In step one, 10 signal values ​​are taken consecutively, i.e., S a1 S a2 ... S a10 Calculate S a1 To S a10 variance S a ; In step two, when S a >S 标 When, take S a1 =S a2 S a2 =S a3 S a9 =S a10 S a10 S a10 The value is assigned to the newly acquired next measurement signal value; In step four, take the signal value S after finally stopping the above steps. a1 S a2 ... S a10 The average value is S1; In step five, 10 signal values ​​are taken consecutively, i.e., S m1 S m2 ... S m10 Calculate S m1 To S m10 variance S m ; In step six, when S m >S 标 When, take S m1 =S m2 S m2 =S m3 S m9 =S m10 S m10 S m10 The value is assigned to the newly acquired next measurement signal value; In step eight, take the signal value S after finally stopping the above steps. m1 S m2 ... S m10 The average value is S2.

3. A method for rapid COD range switching according to claim 1, characterized in that: The preset number of repetitions N1 is 10.

4. A method for rapid COD range switching according to claim 1, characterized in that: The preset number of repetitions N2 is 10.

5. A method for rapid switching of COD range according to claim 1, characterized in that: The value of K1 is 1.

1.

6. A method for rapid switching of COD range according to claim 1, characterized in that: The value of K2 is 0.

9.

7. A method for rapid COD range switching according to claim 1, characterized in that: The time t is 1 minute.

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