CN2570774Y - Closed cycle total organic carbon analytical equipment - Google Patents

Abstract

A closed-circuit circulation total organic carbon analysis device relates to a water quality automatic analysis and on-line monitoring device, which is mainly used for detection of total organic carbon (TOC) content in water bodies. It is composed of sample automatic quantitative sampling device, _CO2 removal device, oxidation device, reactant sampling device, gas water removal device, air pump, infrared gas analyzer (NDIR), instrument measurement and control unit, etc. Since the utility model adopts a closed-circuit circulation device, the _CO2 concentration shows a rising trend, so the conclusion of whether the sample is completely oxidized can be obtained through the change of _CO2 in the oxidation process. With the closed loop device, the CO ₂ sensor can use a NDIR sensor with a larger range, which is cheap and will not cause over-range due to the difference in the CO ₂ release rate of different samples. In the principle of oxidation, the principle of ultraviolet and TiO ₂ photocatalytic oxidation is adopted, and the determination of inorganic carbon IC and total organic carbon TOC can be carried out simultaneously by controlling the opening and closing of the ultraviolet lamp.

Description

A closed-loop total organic carbon analysis device

Technical field The utility model relates to an automatic water quality analysis and online monitoring device, which is mainly used for the detection of total organic carbon (TOC) content in water bodies.

Background technology In water quality monitoring projects, the indicators that characterize the degree of water pollution include COD, BOD, TOC, TN, TP and other indicators. Among them, the detection of total organic carbon (TOC) content in water has attracted increasing attention. It is represented by carbon content A comprehensive indicator of the total amount of organic matter in a water body. At present, COD is mainly used in water quality monitoring in my country, while TOC is mostly used in developed countries instead of COD. The main reason is that TOC is a direct water pollution indicator, and at the same time, the instrument composition is simpler than COD, and it is not used yet. Strong acid and strong alkali, so the maintenance and management tasks of the instrument are much less than that of COD. Due to various reasons, there are few researches on TOC in my country. Many foreign companies promote TOC analysis instruments in my country, which has a certain influence in my country. Even my country's national TOC standard is based on foreign testing instruments. With my country's increasing emphasis on environmental protection, the market for water quality online monitoring instruments is huge. If you rely entirely on foreign products, it will seriously hinder the promotion of the environmental monitoring instrument market in terms of foreign exchange expenditures, product prices, product selection, and after-sales service. Implementation of environmental monitoring policies.

At present, catalytic combustion + NDIR infrared detection and ultraviolet persulfate heating oxidation + NDIR infrared detection methods are mainly used for TOC determination in foreign countries. The former oxidation is relatively complete, but the catalyst is easily poisoned and blocked, and the sample is completely evaporated, resulting in a high moisture content in the gas. The latter requires the use of oxidizing agents such as persulfate, and whether oxidation is completely undetectable is therefore not suitable for all samples, and the measurement accuracy is also low. In addition, the common disadvantages of the two are: firstly, an air pump with a very stable gas flow is required. In addition, due to the continuous gas purging, the concentration of CO2 is low. At the same time, during the oxidation process, the CO2 release curves of different samples are different. NDIR infrared CO2 sensor It is necessary to detect the highest peak and at the same time have better detection accuracy for low concentrations, so the requirements for CO2 sensors are very high and the price is very expensive.

SUMMARY OF THE INVENTION The purpose of this utility model is to overcome the above deficiencies and provide a closed-loop total organic carbon analysis device with simple structure, convenient operation, suitable for both on-line monitoring and laboratory analysis.

The utility model is realized through the following scheme: a closed-circuit circulation total organic carbon analysis device, including: a sample automatic quantitative sampling device 1, a CO2 removal device 2, an oxidation device 3, a reactant sampling device 4, a gas dehydration device 5, and an air pump 6. Infrared gas analyzer (NDIR) 7 , instrument measurement and control unit 8 and gas quantification device 20 . The sample automatic quantitative sampling device 1, the reactant sampling device 4 and the sample oxidation device 3 are respectively connected with a solenoid valve 10, a solenoid valve 12 and pipelines, and the sample automatic quantitative sampling device 1 has solenoid valves 9, 19 and a pump 16 outside the sample automatic quantitative sampling device 1. A solenoid valve 11, a pump 17, and a reagent container 18 are arranged outside the reagent sampling device 4. A photoelectric sensor for automatic liquid level detection is installed on the sample automatic quantitative sampling device 1 and the reagent sampling device 4. The sample oxidation device 3 and the infrared There is a gas dehydration device 5 between the gas analyzer (NDIR) 7, an emptying solenoid valve 13, a gas quantitative device 20, an air pump 6, and a closed-circuit solenoid valve 14 between the infrared gas analyzer (NDIR) 7 and the sample oxidation device 3 , There are intake solenoid valves 13, 15 between the infrared gas analyzer (NDIR) 7 and the CO2 removal device 2 .

Sample automatic quantitative sampling device 1 and reactant sampling device 4 adopt pump suction or gravity self-flowing sampling device. The amount of sample and the injection of reactants are determined by the volume of the quantitative tube, and a photoelectric sensor for automatic liquid level detection is installed on the quantitative tube. When the instrument measurement and control unit 8 issues a sample injection command and the liquid level photoelectric sensor shows that the sample injection is normal, the solenoid valves 9 and 11 are closed, the solenoid valves 10 and 12 are opened, and the quantitative samples and reactants enter the oxidation device 3 automatically.

The oxidation device is the photocatalytic oxidation reactor shown in Figure 2, and the inner glass of the reactor is coated with a nano-TiO2 catalytic film 22, and an ultraviolet oxidation lamp tube 21 is installed. After the sample and reactants enter the reaction chamber 23 of the oxidation device 3, the power supply of the ultraviolet oxidation lamp tube is turned off first, the acid reacts with the inorganic carbon substances in the sample to generate CO2, and the air pump 6 continuously passes the gas quantitative device 20 through the CO2 removal device 2 The obtained fixed volume gas is pumped into the oxidation device 3, and the CO2-containing gas from the oxidation device 3 passes through the gas dehydration device 5, and then enters the infrared gas analyzer (NDIR) 7 for detection, and the instrument measurement and control unit collects it quickly in real time Concentration signal from an infrared gas analyzer (NDIR) 7. The gas coming out from the infrared gas analyzer (NDIR) 7 is not evacuated to the air, but is pumped back to the oxidation device 3 to continue to react with the sample, forming a closed loop system, which circulates until the infrared gas analyzer (NDIR) )7 until the signal reaches a stable equilibrium value, the measured value of the inorganic carbon IC is given accordingly.

The oxidation device of the utility model adopts an ultraviolet TiO2 photocatalytic oxidation device, and can simultaneously measure the inorganic carbon IC and the total organic carbon TOC by controlling the closing and opening of the ultraviolet lamp. The reactant can be phosphoric acid, nitric acid, hydrochloric acid, and phosphoric acid is usually used. The amount of the reactant is subject to the pH value of the mixed sample in the oxidation device being controlled below 3.

After the inorganic carbon has been measured, turn on the power supply of the ultraviolet oxidation lamp tube 21, under the photocatalysis of ultraviolet and titanium dioxide TiO2, the reactant reacts with organic carbon substances to generate CO2, and the air pump 6 will continuously include the gas quantitative device 20, containing The mixed gas of CO2 generated by inorganic carbon is pumped into the oxidation device 3, and the gas coming out from the oxidation device 3 passes through the gas dehydration device 5, and then enters the infrared gas analyzer (NDIR) 7 for detection, and from the infrared gas analyzer (NDIR) 7 The gas that comes out is still pumped back to the oxidation device 3, and this cycle is repeated until the signal of the infrared gas analyzer (NDIR) 7 reaches a stable equilibrium value, and the measured value of the total organic carbon TOC is given accordingly, and is given according to the IC value TC value.

When the measurement of the previous sample is completed, the closed-circuit solenoid valve 14 is closed, and the solenoid valve 13 is opened to empty the sample in the oxidation device 3 . Thereafter, the emptying electromagnetic valve 13 and the closed-circuit electromagnetic valve 14 on the closed-circuit circulating air path are opened. At the same time, the intake electromagnetic valve 15 of the gas metering device 20 is opened, and the gas in the closed circuit is evacuated through the pump 6 . When the gas concentration signal returns to zero, the exhaust solenoid valve 13 and intake solenoid valve 15 are closed, so that the entire closed-circuit circulation system including the gas quantitative device 20 already contains a certain amount of CO2-free gas, waiting for the next one. The start of the test.

To sum up, the utility model adopts advanced ultraviolet photocatalytic oxidation and closed-loop gas analysis technology, which has lower requirements for NDIR infrared CO2 sensor, less requirement for air pump precision, and more accurate sample quantification. The utility model has simple structure and complete functions, is suitable for laboratory TOC analysis, and is also suitable for on-line TOC monitoring.

Description of drawings

Fig. 1 is the structural representation of the utility model.

Fig. 2 is a structural schematic diagram of the ultraviolet photocatalytic oxidation reactor of the utility model.

Detailed ways

The UV and TiO2 photocatalytic oxidation total organic carbon TOC measuring device of the present utility model may not use a closed-circuit circulation gas circuit, but continuously pump constant flow air into the oxidation device 3 through the gas after the CO2 removal device 2 , turn off the power supply of the ultraviolet lamp at this time, and the CO2-containing gas produced by the reaction of the inorganic carbon substance and the reactant passes through the gas dehydration device 5 and then directly enters the infrared gas analyzer (NDIR) 7 for detection and then is emptied. The instrument measurement and control unit 8 calculates the IC content of inorganic carbon according to the CO2 release curve and the standard sample curve. Afterwards, turn on the power supply of the ultraviolet lamp, and continuously pump the constant flow of air through the CO2 removal device 2 into the oxidation device 3, and generate CO2 under the photocatalytic oxidation of ultraviolet light and TiO2, and the gas from the oxidation device 3 passes through the gas After the water removal device 5, it directly enters the infrared gas analyzer (NDIR) 7 for detection and then is emptied. The instrument measurement and control unit 8 calculates the total organic carbon TOC content according to the CO2 release curve and the standard sample curve.

The closed-loop total organic carbon (TOC) analysis device may also not use ultraviolet and TiO2 photocatalytic oxidation, but use catalytic combustion and ultraviolet + persulfate oxidation and other oxidation devices.

Claims (5)

1, one closed cycle formula total organic carbon analytical equipment, it is characterized in that comprising: sample automatic quantitive sampling device (1), remove CO2 device (2), oxidation unit (3), reactant sampling device (4), gas de-watering apparatus (5), air pump (6), infra-red gas analyzer (NDIR) (7), instrument measurement and control unit (8) and gas proportioning device (20), sample automatic quantitive sampling device (1), reactant sampling device (4) is used solenoid valve 10 respectively with sample oxidation unit (3), solenoid valve 12 and pipeline link to each other, solenoid valve (9) is arranged outside the sample automatic quantitive sampling device (1), (19), pump (16), solenoid valve (11) is arranged outside the reactant sampling device (4), pump (17), reaction container (18), sample automatic quantitive sampling device (1), the photoelectric sensor that liquid level detects automatically is installed on the reactant sampling device (4), between sample oxidation unit (3) and the infra-red gas analyzer (NDIR) (7) gas de-watering apparatus (5) is arranged, between infra-red gas analyzer (NDIR) (7) and the sample oxidation unit (3) emptying solenoid valve (13) is arranged, gasometry device (20), air pump (6), closed circuit solenoid valve (14), infra-red gas analyzer (NDIR) (7) and remove between the CO2 device (2) air inlet solenoid valve (13) is arranged, (15).

2, require described analytical equipment according to right 1, it is characterized in that sample automatic quantitive sampling device (1), reactant sampling device (4) adopt pump suction type or flow by gravity formula sampling device.

3, require described analytical equipment according to right 1, it is characterized in that oxidation unit is the photocatalysis oxidation reaction device, on the reactor inner layer glass, be coated with nano titanium oxide TiO2, ultraviolet oxidation fluorescent tube (21).

4, require described analytical equipment according to right 1, it is characterized in that removing between CO2 device (2) and the oxidation unit (3) and link to each other with pump and pipeline.

5, require described analytical equipment according to right 1, it is characterized in that adopting oxidation units such as catalytic combustion and ultraviolet+persulfate oxidation.

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