Desulfurization slurry sulfite monitoring system and monitoring method

Abstract

The invention relates to a desulfurization slurry sulfite monitoring system and monitoring method. The monitoring system comprises a sample extraction device, a developing pool, a detection device, a liquid storage device and a control center, a light source, a sample pool and a detector are arranged in the detection device, and light emitted by the light source penetrates through a solution in the sample pool to reach the detector; the control center is in communication connection with the detector; desulfurization slurry is added into the sample extraction device, an extracting solution in the liquid storage device is added into the sample extraction device and the color developing pool, a shielding agent, a reaction solution and a color developing solution are added into the color developing pool, and the detector transmits absorption spectrum information to the control center. Compared with the prior art, the method has the advantages that the sulfite is fixed by the extracting solution, the measurement error caused by slurry oxidation is reduced, the content of the sulfite in the slurry is measured by adopting a spectrophotometric method after the sulfite reacts with the color developing agent, a measurement result can be directly obtained, characterization through a parameter relation is not needed, the operation is convenient, and the accuracy is high. And the measurement accuracy is high.

Description

Technical Field

[0001] The invention relates to a desulfurization slurry quality analysis technology, and in particular to a desulfurization slurry sulfite monitoring system and a monitoring method. Background Art

[0002] At present, most coal-fired power plants use limestone-gypsum wet desulfurization technology to control flue gas SO2 emissions. After the limestone slurry absorbs sulfur dioxide in the flue gas, it forms calcium sulfite, which is naturally oxidized by the oxygen content in the flue gas and forcedly oxidized by the oxidation fan in the absorption tower to finally crystallize into gypsum. Incomplete oxidation of calcium sulfite will not only affect the quality of gypsum, but also cause chemical scaling and affect the stable operation of the absorption tower; excessive oxidation air will increase the power consumption of the desulfurization system and increase the operating cost, and may also cause false liquid levels in the absorption tower, affecting the slurry density monitoring and causing slurry overflow.

[0003] The sulfite content in the slurry can reflect the degree of slurry oxidation. At present, the sulfite in the desulfurization system of power plants is mainly detected offline by iodine titration. The detection time is long and it is difficult to provide real-time operation guidance. At the same time, the accuracy of the results may be affected by slurry oxidation. Operators often adjust the oxidation air volume based on experience and control the oxygen content at 1.8-2.5 times the theoretical oxygen content, which may lead to under-oxidation or excessive oxidation air. Online monitoring of sulfite to guide the precise adjustment of oxidation air volume in real time is a key means to improve the automatic control level of the desulfurization system and achieve safe, stable and economical operation of the system.

[0004] There are three main methods for online monitoring of sulfite at present. The first is to use iodine titration and related methods to measure the sulfite content online. The second is to measure ORP to indirectly characterize the sulfite level. The third is to use oxidation reaction to convert sulfite into sulfate, and measure the sulfate content to calculate the sulfite content. There are two main problems. First, the ORP measurement cannot directly obtain the sulfite content. It is usually necessary to analyze the relationship between ORP, pH, DO and other parameters and sulfite content. However, the slurry composition is complex and constantly changing, so it is difficult to obtain a more definite relationship. Second, the sulfite content in the slurry is low and easily oxidized. The titration method is used for online determination. It is difficult to determine the titration end point online in complex slurry components, the repeatability is low, and the measurement accuracy is difficult to guarantee.

[0005] Therefore, how to design a desulfurization slurry sulfite monitoring system and method with a simple measurement method and high measurement accuracy is a technical problem that needs to be solved. Summary of the invention

[0006] The purpose of the present invention is to provide a desulfurization slurry sulfite monitoring system and monitoring method in order to overcome the defects of the above-mentioned prior art, such as inconvenient measurement operation and low accuracy.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] According to one aspect of the present invention, a desulfurization slurry sulfite monitoring system is provided, comprising a sample extraction device, a color development cell, a detection device, a liquid storage device and a control center; the inlet of the sample extraction device is connected to the desulfurization slurry, and the outlet is connected to the inlet of the color development cell; a light source, a sample cell and a detector are provided in the detection device, the outlet of the color development cell is connected to the inlet of the sample cell, and the light emitted by the light source passes through the solution in the sample cell to reach the detector; the sample extraction device and the color development cell are connected to the liquid storage device; the control center is in communication connection with the detector;

[0009] The desulfurized slurry is added to the sample extraction device, the extract in the liquid storage device is added to the sample extraction device and the color development pool, the shielding agent, reaction liquid and color development liquid in the liquid storage device are added to the color development pool, and the detector transmits the absorption spectrum information of the solution in the sample pool to the control center.

[0010] As a preferred technical solution, the monitoring system also includes a sampling and dosing device, which is communicatively connected to the control center; the sampling and dosing device includes a sampling pump, an extraction pump, an injection pump and a dosing pump group; the sampling pump is connected to the desulfurization slurry and the sample extraction device, the extraction pump is connected to the sample extraction device and the color development cell, and the injection pump is connected to the color development cell and the sample cell.

[0011] As a preferred technical solution, the liquid storage device includes a shielding agent tank for storing a shielding agent, a reaction liquid tank for storing a reaction liquid, a color developing liquid tank for storing a color developing liquid, and an extraction liquid tank for storing an extraction liquid; the dosing pump group includes a first dosing pump, a second dosing pump, a third dosing pump, a fourth dosing pump, and a fifth dosing pump; the first dosing pump is connected to the color developing cell and the shielding agent tank, the second dosing pump is connected to the color developing cell and the reaction liquid tank, the third dosing pump is connected to the color developing cell and the color developing liquid tank, the fourth dosing pump is connected to the color developing cell and the extraction liquid tank, and the fifth dosing pump is connected to the sample extraction device and the extraction liquid tank.

[0012] As a preferred technical solution, a heating and temperature measuring device is installed on the color developing pool, and the heating and temperature measuring device is communicatively connected with the control center.

[0013] As a preferred technical solution, a stirrer and a pre-filter are provided at the bottom of the sample extraction device; the stirrer is communicatively connected with the control center, and the liquid in the sample extraction device enters the color development pool through the pre-filter.

[0014] As a preferred technical solution, the extracting solution is formaldehyde absorption solution or ethanolamine absorption solution; the shielding agent is aminosulfonate, acetate or dinitrophenol; the reaction solution is sodium hydroxide solution or hydrochloric acid solution; the color developing solution is hydrochloric acid paracarmine solution or p-aminoazobenzene solution.

[0015] As a preferred technical solution, the monitoring system also includes a flushing device, which includes a flushing water pipe, a flushing valve and a drain valve; one end of the flushing valve is connected to the flushing liquid through the flushing water pipe, and the other end is connected to the sample extraction device through the flushing water pipe; one end of the drain valve is connected to the sample extraction device, the colorimetric pool and the detection device through the flushing water pipe, and the other end is connected to the wastewater pool through the flushing water pipe.

[0016] According to another aspect of the present invention, a monitoring method for a desulfurization slurry sulfite monitoring system is provided, which specifically comprises the following steps:

[0017] Step S1, adding the quantitative slurry sample and the extract into the sample extraction device, uniformly mixing and filtering out the suspended matter, and the quantitative clear liquid enters the color development pool;

[0018] Step S2, adding a quantitative extract, a shielding agent, a reaction solution and a color developing solution into the color developing pool, maintaining the color developing pool at a set temperature, and allowing the color-developed liquid to enter the sample pool;

[0019] Step S3, the light source passes through the liquid in the sample pool to reach the detector, and the detector transmits the absorption spectrum information to the control center;

[0020] Step S4, the control center calculates and displays the concentration of sulfite in the desulfurization slurry.

[0021] As a preferred technical solution, in the step S1, the slurry sample is 10 ml, the extract is 40 ml of 0.03% formaldehyde extract, and the clear liquid is 1 ml; in the step S2, the extract is 9 ml of 0.03% formaldehyde extract, the shielding agent is 0.5 ml of 0.6% dinitrophenol shielding agent, the reaction solution is 0.5 ml of 2 mol / L hydrochloric acid reaction solution, and the color developing solution is 1 ml of 0.05% p-aminoazobenzene color developing solution.

[0022] As a preferred technical solution, in the step S1, the slurry sample is 2 ml, the extract is 48 ml of 0.05% triethanolamine extract, and the clear liquid is 0.5 ml; in the step S2, the extract is 9.5 ml of 0.05% triethanolamine extract, the shielding agent is 0.5 ml of 0.5% ammonium sulfamate shielding agent, the reaction solution is 0.5 ml of 1.5 mol / L sodium hydroxide reaction solution, and the color developing solution is 1 ml of 0.02% hydrochloric acid parafuchsin color developing solution.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) The present invention uses an extract to fix the sulfite in the slurry, thereby reducing the measurement error caused by the oxidation of the slurry. After the sulfite reacts with the color developer, the sulfite content in the slurry is determined by spectrophotometry, and the measurement result can be directly obtained without characterization through parameter relationship, and the operation is convenient; at the same time, the measurement error caused by inaccurate judgment of the titration end point in the titration method is avoided, and the measurement accuracy is improved; the present invention has a low detection limit, and the injection volume can be adjusted according to the sulfite concentration level in the slurry, thereby increasing the test range; the process automatic control and online quantitative analysis are realized through the control center, thereby reducing the workload of sampling and analysis personnel, improving the timeliness of the analysis, and providing a basis for the operating personnel to adjust the output of the oxidation fan in real time according to the sulfite content, and providing a possibility for further improving the energy saving level of the desulfurization system.

[0025] 2) The present invention adds the required solution through the sampling and dosing device, and the start and stop and metering are controlled by the control center, so the reagent measurement is convenient and accurate; a heating and temperature measuring device is installed on the color development pool to control the temperature of the solution in the color development pool to maintain the solution at the optimal color development temperature; an agitator and a pre-filter are arranged at the bottom of the sample extraction device to fully stir and extract the added desulfurization slurry and extract, and then filter the clear liquid through the pre-filter, which is convenient to operate.

[0026] 3) The present invention cleans the entire system through a flushing device, without the need for manual cleaning, and is convenient for repeated use. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of a desulfurization slurry sulfite monitoring system of the present invention;

[0028] Figure 2 This is a flow chart of a method for monitoring sulfite in desulfurized slurry according to the present invention;

[0029] The numbers in the figure show:

[0030] 1. Sample extraction device, 2. Color development pool, 3. Detection device, 4. Shielding agent tank, 5. Reaction liquid tank, 6. Color development liquid tank, 7. Extraction liquid tank, 8. Agitator, 9. Pre-filter, 10. Control center, 11. Flushing valve, 12. Sampling pump, 13. Extraction pump, 14. Injection pump, 15. Dosing pump group, 16. Drain valve, 17. Desulfurization slurry sampling tube, 18. Flushing water pipe, 19. Wastewater tank. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0032] The present invention aims to overcome the shortcomings of the prior art and provide a monitoring system and method capable of directly measuring the sulfite concentration in the slurry. The present invention adopts an optical method to measure the sulfite content in the slurry online, with a low detection limit (the detection limit refers to the minimum detection concentration that can be distinguished from noise after the sample to be detected is extracted, processed and detected according to the requirements of the analytical method), high accuracy and strong real-time performance, which provides a basis for operators to adjust the output of the oxidation fan and provides the possibility to further improve the energy saving level of the desulfurization system.

[0033] Example 1

[0034] like Figure 1 As shown, the present invention provides a desulfurization slurry sulfite monitoring system, including a sampling and dosing device, a sample extraction device 1, a color development pool 2, a detection device 3, a liquid storage device, a control center 10 and a flushing device.

[0035] The sampling and dosing device is connected to the control center 10 in communication, and includes a sampling pump 12, an extraction pump 13, a sampling pump 14 and a dosing pump group 15; the sampling pump 12, the extraction pump 13, the sampling pump 14 and the dosing pump group 15 can be a peristaltic pump, a syringe pump or an electromagnetic pump, and the control center 10 performs quantitative sampling and dosing control. The sampling pump 12 connects the desulfurization slurry and the sample extraction device 1, the extraction pump 13 connects the sample extraction device 1 and the color development pool 2, and the sampling pump 14 connects the color development pool 2 and the sample pool; the dosing pump group 15 includes a first dosing pump, a second dosing pump, a third dosing pump, a fourth dosing pump and a fifth dosing pump; the first dosing pump connects the color development pool 2 and the shielding agent tank 4, the second dosing pump connects the color development pool 2 and the reaction liquid tank 5, the third dosing pump connects the color development pool 2 and the color development liquid tank 6, the fourth dosing pump connects the color development pool 2 and the extraction liquid tank 7, and the fifth dosing pump connects the sample extraction device 1 and the extraction liquid tank 7.

[0036] A stirrer 8 and a pre-filter 9 are provided at the bottom of the sample extraction device 1. The stirrer 8 is used to fully mix the desulfurization slurry sample and the extract and extract sulfite. The pre-filter 9 is used to filter the mixed slurry. The filtered clear liquid is added to the color development pool 2.

[0037] The color development pool 2 is provided with a heating and temperature measuring device, and the temperature of the solution is detected by the thermal resistance temperature measuring device. When the temperature is insufficient, the control center 10 controls the resistance wire to heat the solution so as to maintain the solution at the optimal color development temperature.

[0038] The detection device 3 includes a light source, a sample cell and a detector. The light source is a tungsten lamp or a xenon lamp. The light beam emitted by the light source is absorbed by the solution in the cell when passing through the sample cell. The detector measures the absorbance of the sample solution and transmits the absorption spectrum information to the control center 10.

[0039] The liquid storage device is used to store reagents required for the determination process, including a shielding agent tank 4 for storing a shielding agent, a reaction liquid tank 5 for storing a reaction liquid, a color developing liquid tank 6 for storing a color developing liquid, and an extracting liquid tank 7 for storing an extracting liquid. The shielding agent is mainly used to eliminate interferences in the sample, and aminosulfonates, acetates, dinitrophenols, etc. can be selected according to the characteristics of the slurry; the extracting liquid uses formaldehyde absorption liquid or ethanolamine absorption liquid to extract sulfites in the sample; the reaction liquid uses sodium hydroxide solution or hydrochloric acid solution to decompose the compound to release sulfur dioxide; the color developing liquid uses hydrochloric acid paracarmine solution or p-aminoazobenzene solution to react with sulfide to produce a purple-red compound, and the absorbance is proportional to the concentration. The extracting liquid is added to the sample extraction device 1 and the color developing pool 2, and the shielding agent, reaction liquid and color developing liquid in the liquid storage device are added to the color developing pool 2.

[0040] The flushing device includes a flushing water pipe 18, a flushing valve 11 and a drain valve 16. One end of the flushing valve 11 is connected to the flushing liquid through the flushing water pipe 18, and the other end is connected to the sample extraction device 1 through the flushing water pipe 18; one end of the drain valve 16 is connected to the sample extraction device 1, the color development pool 2 and the detection device 3 through the flushing water pipe 18, and the other end is connected to the wastewater pool 19 through the flushing water pipe 18. The control center 10 controls the flushing device to discharge wastewater and flush the system after the detection is completed.

[0041] The control center 10 includes a control module, a calculation module, a display module and a signal transmission module. The control module is used for parameter setting, controlling quantitative sampling, dosing and flushing of the detection system. The calculation module and the display module are used for sulfite concentration calculation and result display. The signal transmission module is used for data storage and uploading.

[0042] Example 2

[0043] like Figure 2 As shown, the present invention provides a method for monitoring sulfite in desulfurized slurry, and the process is as follows:

[0044] The control center 10 sends a control signal, and the sampling pump 12 takes a quantitative slurry sample from the desulfurization slurry sampling tube 17 and enters the sample extraction device 1. At the same time, a quantitative extract is added to the sample extraction device 1. Under the action of the agitator 8, the extract is uniformly mixed with the sample and reacts with sulfite to form a stable form. After stabilization, the sample is filtered by the pre-filter 9 and then the quantitative clear liquid is transported by the sample pump into the color development pool 2. According to the amount of the clear liquid sample, the quantitative extract is added to the color development pool 2 to keep the total amount of the clear liquid and the extract constant in the color development pool 2; at the same time, the dosing pump group 15 is controlled to add a quantitative shielding agent, a reaction liquid and a color development liquid to the color development pool 2; the sample temperature in the color development pool 2 is measured and controlled to maintain at the optimal color development temperature, so that the sample is colored under the action of the agent. The color-developed sample is quantitatively transported by the sample pump 14 into the detector to measure the absorbance, and the measurement result is transmitted to the control center 10. After calculation, the measured slurry sulfite concentration is displayed, and the measurement result is saved and uploaded. After the determination is completed, the control center 10 controls the waste liquid in the sample extraction device 1, the color development pool 2 and the detection device 3 to be discharged to the wastewater pool 19 through the drain valve 16, and opens the flushing valve 11 to flush the system. After flushing three times, the next test begins.

[0045] Example 3

[0046] The present invention provides a method for monitoring sulfite in desulfurization slurry, and the process is as follows:

[0047] The control center 10 sends a control signal, and the sampling pump 12 takes a slurry sample from the desulfurization slurry sampling tube 17 and enters the sample extraction device 1. At the same time, 40 ml of 0.03% formaldehyde extract is added to the sample extraction device 1. The stirrer 8 rotates at 800 r / min. After the formaldehyde extract and the sample are evenly mixed, the suspended matter in the slurry is filtered through the pre-filter 9. The sample pump delivers 1 ml of clear liquid into the color development pool 2, and the dosing pump group 15 adds 9 ml of 0.03% formaldehyde extract, 0.5 ml of 0.6% dinitrophenol shielding agent, 0.5 ml of 2 mol / L hydrochloric acid reaction solution, and 1 ml of 0.05% p-aminoazobenzene color development solution to the color development pool 2; the sample solution temperature is maintained at 30°C. The sample after color development is quantitatively delivered to the detector 3 by the sampling pump 1414, and the absorbance is measured at a wavelength of 520 nm. The measurement result is transmitted to the control center 10, and the measured sulfite concentration of the slurry is displayed after calculation, and the measurement result is saved and uploaded. After the measurement is completed, the control center 10 controls the flushing device to perform flushing.

[0048] Example 4

[0049] The present invention provides a method for monitoring sulfite in desulfurization slurry, and the process is as follows:

[0050] The control center 10 sends a control signal, and the sampling pump 12 takes 2 ml of slurry sample from the desulfurization slurry sampling tube 17 and enters the sample extraction device 1. At the same time, 48 ml of 0.05% triethanolamine extract is added to the sample extraction device 1. The speed of the agitator 8 is 500 r / min. After the triethanolamine extract and the sample are evenly mixed, the suspended matter in the slurry is filtered through the pre-filter 9. 0.5 ml of clear liquid is transported into the color development pool 2 by the sampling pump, and 9.5 ml of 0.05% triethanolamine extract, 0.5 ml of 0.5% ammonium aminosulfonate shielding agent, 0.5 ml of 1.5 mol / L sodium hydroxide reaction solution, and 1 ml of 0.02% hydrochloric acid parafuchsin color development solution are added to the color development pool 2 by the dosing pump group 15; the sample solution temperature is maintained at 30°C. The color-developed sample is quantitatively transported into the detector by the sample pump 14, and the absorbance is measured at a wavelength of 580nm. The measurement result is transmitted to the control center 10, and the measured sulfite concentration of the slurry is displayed after calculation, and the measurement result is saved and uploaded. After the measurement is completed, the control center 10 controls the flushing device to flush.

[0051] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A desulfurization slurry sulfite monitoring system, characterized in that: The invention comprises a sample extraction device (1), a color development cell (2), a detection device (3), a liquid storage device and a control center (10); the inlet of the sample extraction device (1) is connected to the desulfurized slurry, and the outlet is connected to the inlet of the color development cell (2); the detection device (3) is provided with a light source, a sample cell and a detector, the outlet of the color development cell (2) is connected to the inlet of the sample cell, and the light emitted by the light source passes through the solution in the sample cell to reach the detector; the sample extraction device (1) and the color development cell (2) are connected to the liquid storage device; and the control center (10) is connected to the detector in communication; The desulfurized slurry is added to the sample extraction device (1), the extracting liquid in the liquid storage device is added to the sample extraction device (1) and the color development pool (2), the shielding agent, the reaction liquid and the color development liquid in the liquid storage device are added to the color development pool (2), and the detector transmits the absorption spectrum information of the solution in the sample pool to the control center (10).

2. A desulfurization slurry sulfite monitoring system according to claim 1, characterized in that: The monitoring system also includes a sampling and dosing device, which is connected to a control center (10) for communication; the sampling and dosing device includes a sampling pump (12), an extraction pump (13), a sampling pump (14) and a dosing pump group (15); the sampling pump (12) is connected to the desulfurized slurry and the sample extraction device (1), the extraction pump (13) is connected to the sample extraction device (1) and the color development cell (2), and the sampling pump (14) is connected to the color development cell (2) and the sample cell.

3. A desulfurization slurry sulfite monitoring system according to claim 2, characterized in that: The liquid storage device comprises a shielding agent tank (4) for storing a shielding agent, a reaction liquid tank (5) for storing a reaction liquid, a color developing liquid tank (6) for storing a color developing liquid, and an extraction liquid tank (7) for storing an extraction liquid; the dosing pump group (15) comprises a first dosing pump, a second dosing pump, a third dosing pump, a fourth dosing pump, and a fifth dosing pump; the first dosing pump is connected to the color developing cell (2) and the shielding agent tank (4), the second dosing pump is connected to the color developing cell (2) and the reaction liquid tank (5), the third dosing pump is connected to the color developing cell (2) and the color developing liquid tank (6), the fourth dosing pump is connected to the color developing cell (2) and the extraction liquid tank (7), and the fifth dosing pump is connected to the sample extraction device (1) and the extraction liquid tank (7).

4. A desulfurization slurry sulfite monitoring system according to claim 1, characterized in that: A heating and temperature measuring device is installed on the color development pool (2), and the heating and temperature measuring device is communicatively connected with the control center (10).

5. A desulfurization slurry sulfite monitoring system according to claim 1, characterized in that: The sample extraction device (1) is provided with a stirrer (8) and a pre-filter (9) at the bottom; the stirrer (8) is connected to a control center (10) for communication, and the liquid in the sample extraction device (1) passes through the pre-filter (9) and enters the color development pool (2).

6. A desulfurization slurry sulfite monitoring system according to claim 1, characterized in that: The extracting solution is formaldehyde absorption solution or ethanolamine absorption solution; the shielding agent is aminosulfonate, acetate or dinitrophenol; the reaction solution is sodium hydroxide solution or hydrochloric acid solution; the color developing solution is hydrochloric acid paracarmine solution or p-aminoazobenzene solution.

7. A desulfurization slurry sulfite monitoring system according to claim 1, characterized in that: The monitoring system also includes a flushing device, which includes a flushing water pipe (18), a flushing valve (11) and a sewage valve (16); one end of the flushing valve (11) is connected to the flushing liquid through the flushing water pipe (18), and the other end is connected to the sample extraction device (1) through the flushing water pipe (18); one end of the sewage valve (16) is connected to the sample extraction device (1), the color development pool (2) and the detection device (3) through the flushing water pipe (18), and the other end is connected to the wastewater pool (19) through the flushing water pipe (18).

8. A monitoring method using the desulfurization slurry sulfite monitoring system according to claim 1, characterized in that: The specific steps include: Step S1, adding a quantitative slurry sample and an extract into a sample extraction device (1), uniformly mixing and filtering out suspended matter, and the quantitative clear liquid enters a color development pool (2); Step S2, adding a quantitative extract, a shielding agent, a reaction solution and a color developing solution into the color developing pool (2), maintaining the color developing pool (2) at a set temperature, and allowing the color-developed liquid to enter the sample pool; Step S3, the light source passes through the liquid in the sample pool to reach the detector, and the detector transmits the absorption spectrum information to the control center (10); Step S4, the control center (10) calculates and displays the concentration of sulfite in the desulfurized slurry.

9. The monitoring method according to claim 8, characterized in that: In the step S1, the slurry sample is 10 ml, the extract is 40 ml of 0.03% formaldehyde extract, and the clear liquid is 1 ml; in the step S2, the extract is 9 ml of 0.03% formaldehyde extract, the shielding agent is 0.5 ml of 0.6% dinitrophenol shielding agent, the reaction solution is 0.5 ml of 2 mol / L hydrochloric acid reaction solution, and the color developing solution is 1 ml of 0.05% p-aminoazobenzene color developing solution.

10. The monitoring method according to claim 8, characterized in that: In the step S1, the slurry sample is 2 ml, the extract is 48 ml of 0.05% triethanolamine extract, and the clear solution is 0.5 ml; in the step S2, the extract is 9.5 ml of 0.05% triethanolamine extract, the shielding agent is 0.5 ml of 0.5% ammonium sulfamate shielding agent, the reaction solution is 0.5 ml of 1.5 mol / L sodium hydroxide reaction solution, and the color developing solution is 1 ml of 0.02% hydrochloric acid parafuchsin color developing solution.

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