Water quality total organic carbon analyzer and data processing method thereof

Abstract

The present invention relates to a water quality total organic carbon analyzer and a data processing method thereof, wherein the analyzer comprises: a sample bottle; a multi-channel switching valve; a mixed acidification tank; a metering pump, which is used to inject a water sample to be tested or a total organic carbon standard sample and an acid solution into the mixed acidification tank, and is also used to inject the acidified standard sample and water sample into a combustion furnace respectively; a combustion furnace, which is used to burn the acidified standard sample and water sample respectively; a carrier gas generating unit, which comprises an air compressor, a filter, a water remover, a carbon-containing material removal module, a pressure regulating valve, and branched carrier gas branches and air blowing branches connected in sequence, wherein the carrier gas branch is connected to the combustion furnace, and the air blowing branch is connected to the mixed acidification tank; an infrared carbon dioxide sensor, which is used to detect carbon dioxide in the gas output by the combustion furnace and the gas blown out of the mixed acidification tank. The present invention directly uses air as a gas source to generate carrier gas on site, has low use cost, and low operational safety, and does not require safety protection of steel gas cylinders.

Description

Technical Field

[0001] The invention belongs to the technical field of detection and analysis, and specifically relates to a water quality total organic carbon analyzer and a data processing method thereof. Background Art

[0002] The content of organic matter in water is an important indicator to measure the quality of water. Total organic carbon (TOC) is the total amount of organic matter in water expressed by carbon content, which is different from the chemical oxygen demand (COD) in existing technology. Cr , Biochemical oxygen demand BOD 5 and permanganate index COD Mn , which can more accurately reflect the pollution degree of organic pollutants in water.

[0003] Existing TOC analyzers usually use the combustion oxidation-non-dispersive infrared absorption method to measure water quality TOC, but they have the following shortcomings in actual use:

[0004] (1) Using high-purity nitrogen containing oxygen as the carrier gas has high cost and high operational safety requirements, that is, safety protection of steel gas cylinders is required;

[0005] (2) Since the principle of the detector module of the TOC analyzer is the non-dispersive infrared absorption method, if the water is not removed properly, water vapor will seriously affect the accurate determination of CO by the non-dispersive infrared absorption method. 2 The content causes abnormal measurement of the equipment; and currently it is impossible to intelligently determine the degree of water removal;

[0006] (3) In the actual process of measuring water quality TOC, changes in carrier gas flow, temperature and humidity will affect the measurement accuracy of water quality TOC. Summary of the invention

[0007] Based on the above-mentioned shortcomings and deficiencies in the prior art, one of the objects of the present invention is to at least solve one or more of the above-mentioned problems in the prior art. In other words, one of the objects of the present invention is to provide a water quality total organic carbon analyzer and a data processing method thereof that meet one or more of the above-mentioned needs.

[0008] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0009] A water quality total organic carbon analyzer, comprising:

[0010] Sample bottles, including bottles for water samples to be tested, bottles for acid solutions and bottles for total organic carbon standard samples;

[0011] A multi-channel switching valve is connected to the sample bottle and is used to switch the injection of the total organic carbon standard sample, the water sample to be tested, and the acid solution;

[0012] Mixing acidification tank, used for mixing and acidification of water samples or total organic carbon standards to be tested with acid solution;

[0013] A metering pump is used to inject the water sample or total organic carbon standard sample and acid solution to be tested into the mixed acidification tank, and is also used to inject the acidified standard sample and water sample into the combustion furnace respectively;

[0014] A combustion furnace is used to burn the acidified standard sample and water sample respectively;

[0015] The carrier gas generating unit comprises an air compressor, a filter, a dehumidifier, a carbonaceous matter removal module, a pressure regulating valve, and a carrier gas branch and a blowing branch branched after the pressure regulating valve, the carrier gas branch is connected to the combustion furnace, and the blowing branch is connected to the mixed acidification tank; both the carrier gas branch and the blowing branch are provided with a switch valve;

[0016] The infrared carbon dioxide sensor is connected to the combustion furnace and the mixed acidification tank respectively, and is used to detect carbon dioxide from the gas output by the combustion furnace and the gas blown out by the mixed acidification tank; wherein the gas outlet of the mixed acidification tank is connected to the infrared carbon dioxide sensor through an inorganic carbon removal pipeline, and the inorganic carbon removal pipeline is provided with a switch valve;

[0017] The washing and filtering unit is used to perform halogen washing, condensation and particle filtering on the gas output from the combustion furnace and the gas blown out from the mixed acidification tank, and then input them into the infrared carbon dioxide sensor.

[0018] As a preferred solution, the water quality total organic carbon analyzer also includes:

[0019] The carbon dioxide absorber is used to absorb the carbon dioxide output by the infrared carbon dioxide sensor.

[0020] As a preferred solution, the washing and filtering unit comprises a halogen scrubber, a condenser and a particle filter which are connected in sequence, and the particle filter is connected to an infrared carbon dioxide sensor.

[0021] As a preferred solution, the carbon-containing matter removal module includes a CO / HC remover and a carbon dioxide remover connected in sequence.

[0022] As a preferred embodiment, the acid solution is hydrochloric acid.

[0023] As a preferred solution, the sample bottle also includes a zero sample bottle, and the multi-channel switching valve is also used to switch the zero sample injection;

[0024] The process of judging the degree of water removal by the water quality total organic carbon analyzer includes:

[0025] Pass carrier gas and collect peak area signal value MA 1 ;

[0026] Inject zero sample, pass carrier gas, and collect peak area signal value MA 2 ;

[0027] Determine the peak area signal value MA 1 and MA 2 Are they all lower than the preset signal threshold? If so, the water removal is normal; if not, the water removal is abnormal.

[0028] As a preferred embodiment, the zero sample is distilled water or ultrapure water.

[0029] As a preferred solution, the analysis process of the water quality total organic carbon analyzer includes:

[0030] The analysis process of the water quality total organic carbon analyzer includes:

[0031] (1) Determine the degree of water removal; if the water removal is normal, go to step (2);

[0032] (2) Add zero sample, pass carrier gas, and collect peak area signal value MA 零样 ;pass MA 0 / MA 零样 Correct the baseline of the water sample to be tested; where: MA 0 The peak area signal value collected when zero sample is introduced and carrier gas is passed during analyzer calibration;

[0033] (3) Add the water sample to be tested, pass the carrier gas, and collect the peak area signal value MA s and converted to total organic carbon concentration.

[0034] The present invention also provides a data processing method for the water quality total organic carbon analyzer as described in the above scheme. If the total organic carbon concentration is higher than 25 mg / L, based on the carrier gas flow rate V , Ambient temperature T ,humidity H Peak area signal value MA s Correction is performed to obtain the corrected peak area signal value MA * :

[0035] ;

[0036] according to Converted to total organic carbon concentration C ;

[0037] in, k 1 , k 2 , k 3 ,k 4 , b 0 , b 1 , K 1 , B 1 are fitting coefficients, V s and V b are the carrier gas flow rates for the water sample to be tested and the standard sample to be tested, T s and T b are the ambient temperatures of the infrared carbon dioxide sensor during the water sample and standard sample testing, H s and H b They are the ambient humidity of the infrared carbon dioxide sensor during the detection of the water sample to be tested and the standard sample.

[0038] The present invention also provides a data processing method for the water quality total organic carbon analyzer as described in the above scheme. If the total organic carbon concentration is not higher than 25 mg / L, based on the ambient temperature T ,humidity H Peak area signal value MA s Correction is performed to obtain the corrected peak area MA * :

[0039] ;

[0040] according to , and the corrected total organic carbon concentration was obtained C ;

[0041] in, k 5 , k 6 , k 7 , b 2 , K 2 are fitting coefficients, T s and T b are the ambient temperatures of the infrared carbon dioxide sensor during the water sample and standard sample testing, H s and H bThey are the ambient humidity of the infrared carbon dioxide sensor during the detection of the water sample to be tested and the standard sample.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The carrier gas of the present invention directly uses air as the gas source, generates the carrier gas on site, has low use cost, and has low operational safety, and does not require safety protection of steel gas cylinders;

[0044] (2) The present invention realizes intelligent judgment of the degree of water removal, ensuring the accuracy of subsequent total organic carbon concentration detection;

[0045] (3) The present invention comprehensively considers the influence of carrier gas flow rate, temperature and humidity on water quality TOC detection, effectively improving the accuracy of water quality TOC detection; in addition, for low concentration conditions, an additional correction algorithm is designed to further improve the accuracy of low concentration water quality TOC detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a schematic structural diagram of a water quality total organic carbon analyzer according to embodiment 1 of the present invention;

[0047] Figure 2 1 is a comparison diagram of the effects of the data processing method of Example 1 of the present invention and Comparative Example 1;

[0048] Figure 3 It is a rendering of the data processing method for low-concentration TOC detection according to Example 1 of the present invention. DETAILED DESCRIPTION

[0049] In order to more clearly illustrate the embodiments of the present invention, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other accompanying drawings and other implementation methods can be obtained based on these accompanying drawings without creative work.

[0050] Embodiment 1:

[0051] like Figure 1 As shown, the total organic carbon analyzer for water quality of this embodiment includes a zero sample bottle 1, a water sample bottle to be tested 2, an acid solution bottle 3, a total organic carbon standard sample bottle 4, a multi-channel switching valve 5, a metering pump 6, a mixing acidification tank 7, a combustion furnace 8, a carrier gas generating unit, a washing and filtering unit, an infrared carbon dioxide sensor 9 and a carbon dioxide absorber 10.

[0052] Specifically, the zero sample in the zero sample bottle 1 of this embodiment is ultrapure water or distilled water, and the acid solution in the acid solution bottle 3 is dilute hydrochloric acid, and the concentration of the dilute hydrochloric acid is preferably 2%.

[0053] The different channel interfaces of the multi-channel switching valve 5 of this embodiment are respectively connected to the zero sample bottle 1, the water sample bottle 2 to be tested, the acid solution bottle 3, and the total organic carbon standard sample bottle 4, for switching the injection of the total organic carbon standard sample, the water sample to be tested, and the acid solution; the specific connection structure can refer to the prior art and will not be repeated here; the common channel of the multi-channel switching valve 5 is connected to the metering pump 6, for injecting the water sample to be tested or the total organic carbon standard sample and the acid solution into the mixed acidification tank 7, and also for injecting the acidified standard sample and water sample into the combustion furnace 8 respectively.

[0054] The mixed acidification tank 7 is used for mixing the water sample to be tested or the total organic carbon standard sample with the acid solution for acidification, so as to remove the inorganic carbon in the water sample to be tested.

[0055] The combustion furnace 8 of this embodiment is used to burn the zero sample, the acidified standard sample and the water sample respectively. The temperature of the combustion furnace is controlled at 680±20°C and can reach a maximum of 1000°C. The specific combustion process can refer to the existing technology and will not be repeated here.

[0056] The carrier gas generating unit of this embodiment includes an air compressor a, a particulate filter b, a dehydrator c, a CO / HC remover d, a carbon dioxide remover e, a pressure regulating valve f, and a carrier gas branch I and a blowing branch II branching after the pressure regulating valve f, which are connected in sequence. The carrier gas branch I is connected to the combustion furnace 8, and the blowing branch II is connected to the mixing acidification tank 7; the carrier gas branch I is provided with a switch valve g1, a steady flow valve h1, a float flowmeter i1 and a check valve j in sequence along its flow path, and the blowing branch II is provided with a switch valve g2, a steady flow valve h2 and a float flowmeter i2 in sequence along its flow path.

[0057] The washing and filtering unit of this embodiment is connected in sequence along the gas outlet of the combustion furnace 8 to the gas inlet of the infrared carbon dioxide sensor 9, including a condensate collector 11, a switch valve 12, a three-way valve 13, a halogen scrubber 14, a buffer tube 15, a condenser 16, and a multi-stage particle filter 17, and the multi-stage particle filter 17 is connected to the gas inlet of the infrared carbon dioxide sensor 9. The condensate collector 11 is provided with a waste liquid valve F1 for draining liquid; the buffer tube 15 is used to prevent too much solution in the halogen scrubber 14 from entering the condenser 16, thereby affecting the condensation effect; the buffer tube 15 is provided with a waste liquid valve F2 for draining liquid.

[0058] The infrared carbon dioxide sensor 9 of this embodiment is connected to the combustion furnace 8 and the mixing acidification tank 7 respectively, and is used to detect carbon dioxide in the gas output by the combustion furnace and the gas blown out by the mixing acidification tank; wherein, the gas outlet of the mixing acidification tank 7 is connected to the three-way valve 13 through the inorganic carbon removal pipeline 18 to be connected to the infrared carbon dioxide sensor 9; the inorganic carbon removal pipeline 18 is provided with a three-way valve 19 for connecting with the air.

[0059] The carbon dioxide absorber 10 of this embodiment is used to absorb the carbon dioxide output by the infrared carbon dioxide sensor 9 to prevent it from being directly discharged into the atmosphere.

[0060] The analysis process of the water quality total organic carbon analyzer of this embodiment includes the following steps:

[0061] (1) Determine the degree of water removal; if the water removal is normal, go to step (2);

[0062] Specifically, the process of determining the degree of water removal includes:

[0063] Pass carrier gas and collect peak area signal value MA 1 ;

[0064] Inject zero sample, pass carrier gas, and collect peak area signal value MA 2 ;

[0065] Determine the peak area signal value MA 1 and MA 2 Are they all lower than the preset signal threshold (e.g. 0.2)? If so, the water removal is normal; if not, the water removal is abnormal, and an alarm prompts that the water needs to be completely removed before analysis and testing;

[0066] (2) Add zero sample, pass carrier gas, and collect peak area signal value MA ; The baseline of the water sample to be measured is MA 0 / MA , the ratio must be between 0.98 and 1.02; MA 0 The peak area signal value collected when zero sample is introduced and carrier gas is passed during analyzer calibration;

[0067] (3) Add the water sample to be tested, pass the carrier gas, and collect the peak area signal value MA 4 And converted into total organic carbon concentration, namely TOC concentration.

[0068] The peak area signal value of this embodiment, i.e., the peak area. According to the detected TOC concentration obtained by linear fitting of the conventional peak area and the total organic carbon concentration (i.e., the linear fitting of Comparative Example 1), it is judged whether the detected TOC concentration is higher than 25 mg / L, and different data processing methods are performed according to the judgment result, as follows:

[0069] If the TOC concentration is higher than 25 mg / L, the correction algorithm 1 is used based on the carrier gas flow rate. V , Ambient temperature T ,humidity H Peak area signal value MA sCorrection is performed to obtain the corrected peak area signal value MA * :

[0070] ;

[0071] according to Converted to total organic carbon concentration C ;

[0072] in, k 1 , k 2 , k 3 , k 4 , b 0 , b 1 , K 1 , B 1 are fitting coefficients, V s and V b are the carrier gas flow rates for the water sample to be tested and the standard sample to be tested, T s and T b are the ambient temperatures of the infrared carbon dioxide sensor during the water sample and standard sample testing, H s and H b They are the ambient humidity of the infrared carbon dioxide sensor during the detection of the water sample to be tested and the standard sample.

[0073] If the TOC concentration is not higher than 25 mg / L, the modified algorithm 2 is used based on the ambient temperature. T ,humidity H Peak area signal value MA s Correction is performed to obtain the corrected peak area MA * :

[0074] ;

[0075] according to , and the corrected total organic carbon concentration was obtained C ;

[0076] in, k 5 , k 6 , k7 , b 2 , K 2 are fitting coefficients, T s and T b are the ambient temperatures of the infrared carbon dioxide sensor during the water sample and standard sample testing, H s and H b They are the ambient humidity of the infrared carbon dioxide sensor during the detection of the water sample to be tested and the standard sample.

[0077] The above fitting coefficients in this embodiment can all be obtained by fitting with standard samples. The specific fitting process can be referred to the prior art and will not be described in detail here.

[0078] In this embodiment, the carrier gas flow rate can be obtained by the float flowmeter, and the ambient temperature and humidity can be obtained by detecting the temperature and humidity sensors installed on site.

[0079] Comparative Example 1:

[0080] The data processing method of the water quality total organic carbon analyzer in this comparative example is different from that in Example 1 in that:

[0081] The total organic carbon concentration was directly obtained by using the linear conversion relationship between the peak area signal value and the total organic carbon concentration, without considering the influence of carrier gas flow rate, ambient temperature and humidity.

[0082] The data processing method of the above-mentioned embodiment 1 is compared and verified with the data processing method of comparative example 1 as follows:

[0083] The peak areas of 2, 5, 10, 20, 50, and 80 mg / L total organic carbon TOC standards were measured, and the corresponding peak areas were 1620.2, 2105.7, 2700.6, 6050.1, 11003.5, and 20417.6, respectively. With TOC concentration as the abscissa and peak area as the ordinate, the straight line obtained by fitting using the data processing method of Comparative Example 1 (i.e., the corresponding straight line before correction) is as follows: Figure 2 As shown, the relative error with the standard concentration is calculated, and the result shows that the error is large, as shown in Table 1. Using the correction algorithm 1 in the data processing method of Example 1 above, the corrected peak areas are 1287.2, 1913.2, 2997.1, 5565.8, 11946.4, and 18537.7, respectively. With TOC concentration as the abscissa and peak area as the ordinate, the fitted straight line (i.e., the corresponding straight line after correction) is as shown in Table 1. Figure 2As shown in Table 1, the linearity is significantly improved, and the relative error with the standard concentration is calculated. The results show that when the standard concentration is greater than 25 mg / L, the accuracy is high, but when it is less than 25 mg / L, the accuracy is relatively poor, as shown in Table 1.

[0084] Table 1 Comparative test results of water quality TOC detection

[0085] .

[0086] Based on the relatively poor accuracy when the peak area is lower than 25 mg / L, the present embodiment adopts the above correction algorithm 2 to correct the peak area. The corrected peak areas are 1158.3, 2106.2, 3405.5 and 5485.8 respectively. With TOC concentration as the abscissa and peak area as the ordinate, the fitted curve is as follows: Figure 3 The relative error with the standard concentration was calculated, and the results showed that the accuracy of low concentrations was significantly improved, as shown in Table 2.

[0087] Table 2 Comparative test results of water quality TOC detection

[0088] .

[0089] In summary, the correlation between TOC peak area and concentration obtained by the data processing method of Example 1 of the present invention is much higher than that of the data processing method of Comparative Example 1. Therefore, the data processing method of the water quality total organic carbon analyzer of the present invention effectively improves the accuracy of TOC analysis.

[0090] The above description is only a detailed description of the preferred embodiments and principles of the present invention. For ordinary technicians in this field, according to the ideas provided by the present invention, there will be changes in the specific implementation methods, and these changes should also be regarded as the protection scope of the present invention.

Claims

1. Analysis method of water quality total organic carbon analyzer, It is characterized in that The water quality total organic carbon analyzer comprises: Sample bottles, including bottles for water samples to be tested, bottles for acid solutions and bottles for total organic carbon standard samples; A multi-channel switching valve is connected to the sample bottle and is used to switch the injection of the total organic carbon standard sample, the water sample to be tested, and the acid solution; Mixing acidification tank, used for mixing and acidification of water samples or total organic carbon standards to be tested with acid solution; A metering pump is used to inject the water sample or total organic carbon standard sample and acid solution to be tested into the mixed acidification tank, and is also used to inject the acidified standard sample and water sample into the combustion furnace respectively; A combustion furnace is used to burn the acidified standard sample and water sample respectively; The carrier gas generating unit comprises an air compressor, a filter, a dehumidifier, a carbonaceous matter removal module, a pressure regulating valve, and a carrier gas branch and a blowing branch branched after the pressure regulating valve, the carrier gas branch is connected to the combustion furnace, and the blowing branch is connected to the mixed acidification tank; both the carrier gas branch and the blowing branch are provided with a switch valve; The infrared carbon dioxide sensor is connected to the combustion furnace and the mixed acidification tank respectively, and is used to detect carbon dioxide from the gas output by the combustion furnace and the gas blown out by the mixed acidification tank; wherein the gas outlet of the mixed acidification tank is connected to the infrared carbon dioxide sensor through an inorganic carbon removal pipeline, and the inorganic carbon removal pipeline is provided with a switch valve; The washing and filtering unit is used to perform halogen washing, condensation and particle filtering on the gas output from the combustion furnace and the gas blown out from the mixed acidification tank, and then input them into the infrared carbon dioxide sensor; The sample bottle also includes a zero sample bottle, and the multi-channel switching valve is also used to switch the zero sample injection; The analysis process of the water quality total organic carbon analyzer includes: (1) Determine the degree of water removal; if the water removal is normal, go to step (2); (2) Add zero sample, pass carrier gas, and collect peak area signal value MA 零样 ; by MA 0 / MA 零样 Correct the baseline of the water sample to be tested; where MA 0 The peak area signal value collected when zero sample is introduced and carrier gas is passed during analyzer calibration; (3) Add the water sample to be tested, pass the carrier gas, and collect the peak area signal value MA s and converted to total organic carbon concentration; If the total organic carbon concentration is higher than 25 mg / L, the peak area signal value MA is calculated based on the carrier gas flow rate V, ambient temperature T, and humidity H. s Correction is performed to obtain the corrected peak area signal value MA * : MA * =MA s *In{[k 1 (V s -V b ) 2 +k 2 (V s -V b )+k 3 (T s -T b )+k 4 (H s -H b )+b 1 ]}+b 0 ; According to MA * =K 1 *C+B 1 The total organic carbon concentration C was obtained by conversion; Among them, k 1 , k 2 , k 3 , k 4 、b 0 、b 1 , K 1 , B 1 are fitting coefficients, V s and V b are the carrier gas flow rates for the water sample to be tested and the standard sample, respectively, s and T b are the ambient temperatures of the infrared carbon dioxide sensor during the water sample and standard sample testing, respectively. s and H b They are the ambient humidity of the infrared carbon dioxide sensor when testing the water sample to be tested and the standard sample; If the total organic carbon concentration is not higher than 25 mg / L, the peak area signal value MA is calculated based on the ambient temperature T and humidity H. s Correction is performed to obtain the corrected peak area MA * : According to MA * =K 2 *C 0.6763 , and obtain the corrected total organic carbon concentration C; Among them, k 5 , k 6 , k 7 、b 2 , K 2 are fitting coefficients, T s and T b are the ambient temperatures of the infrared carbon dioxide sensor during the water sample and standard sample testing, respectively. s and H b They are the ambient humidity of the infrared carbon dioxide sensor during the detection of the water sample to be tested and the standard sample.

2. The analysis method of the water quality total organic carbon analyzer according to claim 1, It is characterized in that Also includes: The carbon dioxide absorber is used to absorb the carbon dioxide output by the infrared carbon dioxide sensor.

3. The analysis method of the water quality total organic carbon analyzer according to claim 1, It is characterized in that The washing and filtering unit comprises a halogen scrubber, a condenser and a particle filter which are connected in sequence, and the particle filter is connected to an infrared carbon dioxide sensor.

4. The analysis method of the water quality total organic carbon analyzer according to claim 1, It is characterized in that The carbon-containing matter removal module includes a CO / HC remover and a carbon dioxide remover connected in sequence.

5. The analysis method of the water quality total organic carbon analyzer according to claim 1, It is characterized in that The acid solution is hydrochloric acid.

6. The analysis method of the water quality total organic carbon analyzer according to any one of claims 1 to 5, It is characterized in that The process of judging the degree of water removal by the water quality total organic carbon analyzer includes: Pass carrier gas and collect peak area signal value MA 1 ; Inject zero sample, pass carrier gas, and collect peak area signal value MA 2 ; Determine the peak area signal value MA 1 and MA 2 Are they all lower than the preset signal threshold? If so, the water removal is normal; if not, the water removal is abnormal.

7. The analysis method of the water quality total organic carbon analyzer according to claim 6, It is characterized in that The zero sample is distilled water or ultrapure water.

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