A method and device for online monitoring of denitrification urea quality

Abstract

The present application discloses an online monitoring method for the quality of denitrification urea, including obtaining the conductivity of the denitrification urea solution, and performing data processing and correction; calculating the conductivity using an algorithm model to obtain an impurity content result characterized by inorganic salts; comparing the impurity content result with an impurity content warning value to obtain a comparison result; and judging the quality of the denitrification urea based on the comparison result. The above-mentioned online monitoring method for the quality of denitrification urea provided in the present application can quickly, timely and reliably monitor the content of impurities mixed in the denitrification urea, strictly control the quality of urea, promptly discover quality problems, and ensure the safe operation of the denitrification system. The present application also provides an online monitoring device for the quality of denitrification urea.

Description

Technical Field

[0001] The invention belongs to the technical field of supporting equipment for power plants, and in particular relates to a method and a device for online monitoring the quality of denitrification urea. Background Art

[0002] The normal operation of the flue gas denitrification system in thermal power plants is the key to ensuring NO x Meet ultra-low emission ≤50mg / Nm 3 Regulations, and important environmental protection treatment measures for enterprises to meet emission standards for pollutants. In flue gas denitrification technology, the selective catalytic reduction method (SCR) is highly efficient, mature in technology, and widely used. Ammonia is used as a reducing agent for SCR denitrification, and is mainly produced by liquid ammonia and urea. In recent years, people have paid more and more attention to the potential dangers in the use of liquid ammonia, and urea hydrolysis or pyrolysis technology has been increasingly widely used in SCR denitrification systems. In the technology of urea hydrolysis or pyrolysis to produce ammonia, it is necessary to first prepare a urea solution with a concentration of about 50%, and then heat it to produce ammonia. Urea hydrolysis uses steam as a heating source, which has better operating economy, higher safety, and wider application.

[0003] It should be noted that urea, also known as carbamide, has a simplified molecular formula of CO(NH2)2 and a nitrogen content of 46.66%. As an important chemical product, urea is widely used in agriculture, industry, medicine and other industries. The amount of urea used in flue gas denitrification of power generation enterprises is roughly 10 to 40 t / d. It is a bulk raw material and is subject to factory acceptance according to enterprise management requirements. Urea is used in the preparation of denitrification reducing agents and is generally required to meet the requirements for industrial urea in GB / T2440-2017 "Urea". The main quality indicators include total nitrogen (N) ≥ 46.0%; biuret ≤ 1.0%; moisture ≤ 0.7%; iron (Fe) ≤ 0.0010%; alkalinity (NH3) ≤ 0.03%; sulfate (SO4 2-)≤0.020%; water insoluble matter≤0.040%. Under normal circumstances, the purity of urea for denitrification can reach more than 98.6% based on a total nitrogen content of more than 46.0%. The content of other impurities is limited and its impact is controllable. Due to the huge increase in the demand for urea, the quality of urea products on the market is uneven, and there are impurities that affect the safe operation of the denitrification system. Common impurities in urea for denitrification mainly include sodium chloride, ammonium chloride and potassium chloride, etc. The appearance of these impurities is highly similar to urea, and they are easily soluble in water. They are not easy to be found when mixed into urea. The content of such impurities in the urea of ​​some power generation companies is relatively high, which directly affects the operation of the denitrification system and endangers the safety of the equipment. One of the main reasons for this problem is that the total nitrogen detection method is time-consuming and difficult to operate. According to GB / T2441.1-2008 "Determination of Urea Part 1: Determination of Total Nitrogen" Article 3.1, the post-distillation titration method has a long detection process, high operating requirements, and certain risks. This method is not widely used in the acceptance inspection of power generation companies. After some power plants take samples, they outsource the inspection to a third-party inspection agency for acceptance, but it is difficult to take samples and send them for inspection batch by batch, and the timeliness of the inspection results cannot be guaranteed. Therefore, there is no rapid detection method for impurities mixed in denitrification urea in the conventional standard inspection method for urea quality, and it cannot be used for online early warning monitoring of urea quality. Online detection of impurities mixed in urea is an urgent problem to be solved. Summary of the invention

[0004] To solve the above problems, the present invention provides a method and device for online monitoring of denitrification urea quality, which can quickly, timely and reliably monitor the content of impurities mixed in denitrification urea, strictly control the quality of urea, discover quality problems in time, and ensure the safe operation of the denitrification system.

[0005] The present invention provides a method for online monitoring of denitrification urea quality, comprising:

[0006] Obtain the conductivity of the denitrification urea solution, and perform data processing and correction;

[0007] The conductivity is calculated using an algorithm model to obtain an impurity content result characterized by inorganic salts;

[0008] Comparing the impurity content result with the impurity content warning value to obtain a comparison result;

[0009] The quality of the denitrification urea is judged according to the comparison results.

[0010] Preferably, in the above-mentioned method for online monitoring of denitrification urea quality, after judging the denitrification urea quality, the method further comprises:

[0011] When the impurity content result exceeds the impurity content warning value, an alarm signal is issued.

[0012] Preferably, in the above-mentioned method for online monitoring of denitrification urea quality, before calculating the conductivity using the algorithm model, it also includes:

[0013] The algorithm model is calibrated, verified and debugged at multiple points using a chloride standard solution, and multiple groups of sample data are obtained to evaluate, debug and verify the parameters of the algorithm model, which is a multiple linear regression curve.

[0014] Preferably, in the above-mentioned denitrification urea quality online monitoring method, the data processing and correction include:

[0015] The conductivity of the denitrification urea solution is differentiated and compared with an input set value to determine a correction value of the conductivity of the urea solution.

[0016] Preferably, in the above-mentioned method for online monitoring of denitrification urea quality, it also includes:

[0017] The impurity content result is characterized by multiplying the algorithm model monitoring value by the comprehensive coefficient, wherein the comprehensive coefficient ranges between 1 and 3.6;

[0018] The impurity content result and the comparison result are displayed.

[0019] Preferably, in the above-mentioned method for online monitoring of denitrification urea quality, it also includes:

[0020] The impurity content result and the comparison result are stored.

[0021] Preferably, in the above-mentioned method for online monitoring of denitrification urea quality, it also includes:

[0022] The impurity content result and the comparison result are transmitted to a centralized control room for real-time monitoring by production personnel.

[0023] The present invention provides an online monitoring device for the quality of denitrification urea, comprising a measuring cell installed in parallel with an outlet pipeline of a urea dissolving pump through an inlet isolation door and an outlet isolation door, a sensor extending into the measuring cell, the sensor being used to obtain the conductivity and temperature of the denitrification urea solution, the other end of the sensor being connected to an industrial computer, the industrial computer comprising a processing unit for data processing and correction, a calculation unit for calculating the conductivity using an algorithm model to obtain an impurity content result characterized by inorganic salts, a comparison unit for comparing the impurity content result with an impurity content warning value to obtain a comparison result, and an evaluation unit for evaluating the quality of the denitrification urea according to the comparison result.

[0024] Preferably, in the above-mentioned denitrification urea quality online monitoring device, the industrial computer further comprises a temperature control component for controlling the measurement temperature to eliminate the influence of the difference between the measurement temperature and the temperature during calibration.

[0025] Preferably, in the above-mentioned denitrification urea quality online monitoring device, the industrial computer also includes an alarm component for issuing an alarm signal when the impurity content result exceeds the impurity content warning value.

[0026] It can be known from the above description that the above-mentioned denitrification urea quality online monitoring method provided by the present invention includes first obtaining the conductivity of the denitrification urea solution, and performing data processing and correction; then using the algorithm model to calculate the conductivity to obtain the impurity content result characterized by inorganic salts; then comparing the impurity content result with the impurity content warning value to obtain a comparison result; finally, judging the quality of the denitrification urea according to the comparison result, so that the content of impurities mixed in the denitrification urea can be quickly, timely and reliably monitored, the quality of urea can be strictly controlled, quality problems can be discovered in time, and the safe operation of the denitrification system can be ensured. The above-mentioned denitrification urea quality online monitoring device provided by the present invention has the same advantages as the above-mentioned denitrification urea quality online monitoring method. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0028] Figure 1 A schematic diagram of an embodiment of a method for online monitoring of denitrification urea quality provided by the present invention;

[0029] Figure 2 An overall schematic diagram of an embodiment of an online monitoring device for denitrification urea quality provided by the present invention;

[0030] Figure 3 A schematic diagram of the composition of an industrial computer of an online monitoring device for denitrification urea quality provided by the present invention;

[0031] Figure 4 A schematic diagram of a specific example of an industrial computer. DETAILED DESCRIPTION

[0032] The core of the present invention is to provide a method and device for online monitoring of denitrification urea quality, which can quickly, timely and reliably monitor the content of impurities mixed in denitrification urea, strictly control the quality of urea, discover quality problems in time, and ensure the safe operation of the denitrification system.

[0033] 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 only 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 are within the scope of protection of the present invention.

[0034] The implementation example of the method for online monitoring of denitrification urea quality provided by the present invention is as follows: Figure 1 As shown, Figure 1 The present invention provides a schematic diagram of an embodiment of a method for online monitoring of denitrification urea quality, the method comprising the following steps:

[0035] S1: Obtain the conductivity of the denitrification urea solution, and perform data processing and correction;

[0036] Specifically, a device installed in parallel on the outlet pipeline of the urea dissolution pump can be used to obtain the conductivity of the denitrification urea solution, and a programmable PLC can be used to perform data processing and correction on the conductivity of the urea solution measured online and continuously.

[0037] S2: Calculate the conductivity using the algorithm model to obtain the impurity content result represented by inorganic salts;

[0038] It should be noted that the algorithm model may be a model that has been calibrated and verified, and the inorganic salt may be, but is not limited to, potassium salt and ammonium salt, etc.

[0039] S3: Compare the impurity content result with the impurity content warning value to obtain a comparison result;

[0040] That is, when the impurity content result does not exceed the impurity content warning value, the comparison result is normal, and when the impurity content exceeds the impurity content warning value, the comparison result is abnormal.

[0041] S4: According to the comparison results, the quality of the denitrification urea is judged.

[0042] That is to say, when the impurity content exceeds the impurity content warning value, it proves that the quality of the denitrification urea is unqualified, and the higher the impurity content, the lower the quality of the denitrification urea. This realizes rapid, timely and reliable early warning monitoring of the denitrification urea quality.

[0043] During the specific operation, the correction program, algorithm model, evaluation program and alarm program are first established in the PLC, and then the algorithm model is calibrated and verified, and then the conductivity of the urea solution is measured and the conductivity is corrected. Then, the corrected conductivity is input into the algorithm model, and the algorithm model calculates the impurity content, judges whether the impurity content exceeds the warning value, and finally outputs the impurity content and the evaluation result.

[0044] From the above description, it can be seen that in the embodiment of the above-mentioned denitrification urea quality online monitoring method provided by the present invention, since it includes first obtaining the conductivity of the denitrification urea solution, and performing data processing and correction; then using the algorithm model to calculate the conductivity to obtain the impurity content result characterized by inorganic salts; then comparing the impurity content result with the impurity content warning value to obtain a comparison result; finally, judging the quality of the denitrification urea according to the comparison result, it is possible to fully consider the properties and influences of different impurity ions, quickly, timely and reliably monitor the content of impurities mixed in the denitrification urea, strictly control the urea quality, promptly discover quality problems, and ensure the safe operation of the denitrification system.

[0045] In a specific embodiment of the above-mentioned method for online monitoring of denitrification urea quality, after judging the quality of denitrification urea, the following steps may also be included:

[0046] When the impurity content result exceeds the impurity content warning value, an alarm signal is issued.

[0047] Specifically, according to the requirements for industrial urea in GB / T 2440-2017 Urea, the main quality indicator total nitrogen (N) ≥ 46.0%, based on which the purity of urea for denitrification should reach 98.6% or more, that is, the content of other impurities should not be greater than 1.4%, which is the maximum value of the impurity content. For safety reasons, this embodiment uses this maximum value * safety factor as a warning value to judge the quality of urea, and the safety factor is 0 to 1.

[0048] In another specific embodiment of the above-mentioned method for online monitoring of denitrification urea quality, before calculating the conductivity using the algorithm model, the following steps may also be included:

[0049] The algorithm model was calibrated, verified and debugged at multiple points using a chloride standard solution, and multiple groups of sample data were obtained to evaluate, debug and verify the parameters of the algorithm model, which was a multiple linear regression curve.

[0050] The mathematical expression of the above algorithm model can be:

[0051] Y=β0+β1X 1i +β2X 2i +μ i , i=1,2,…n

[0052] Where, Y——conductivity, μS / cm;

[0053] β0——intercept of regression curve;

[0054] β1——partial regression coefficient 1, which represents the influence of the change of impurity content in urea on conductivity;

[0055] β2——partial regression coefficient 2, characterizing the influence of urea conductivity on conductivity over time;

[0056] X1——impurity content, %;

[0057] X2——time, min, starting from t1;

[0058] μ—-Random error, μS / cm.

[0059] After determining the monitoring environment and conditions, standard solutions are used for multi-point calibration and debugging, multiple sets of sample data are obtained, and model parameters are evaluated, debugged, and verified. Chloride salt is generally used for calibration and verification of the algorithm model. The test shows that the content of chloride salt in urea is significantly correlated with the increased conductivity of urea solution. When the impurity content is 0-5%, the regression curve determination coefficient R 2 >0.998, sensitivity is between 0.01% and 0.05%.

[0060] In another specific embodiment of the above-mentioned method for online monitoring of denitrification urea quality, data processing and correction may include the following steps:

[0061] The conductivity of the denitrification urea solution is differentiated and compared with the input set value to determine the correction value of the conductivity of the urea solution.

[0062] Specifically, the correction program stored in the PLC can be used to implement the differential processing of the urea online measurement conductivity, and compared with the input set value to determine the correction value of the urea solution conductivity.

[0063] In a preferred embodiment of the above-mentioned method for online monitoring of denitrification urea quality, the following steps may also be included:

[0064] The impurity content result is represented by the result of multiplying the algorithm model monitoring value by the comprehensive coefficient, wherein the comprehensive coefficient ranges between 1 and 3.6;

[0065] Displays the impurity content results and comparison results.

[0066] Specifically, the early warning monitoring is aimed at impurities mixed in urea that are detrimental to the denitrification operation. The more common impurities in urea are sodium chloride, potassium salts and ammonium salts used as compound fertilizers. The influence of such substances on the conductivity of urea solution is related to its ion composition. This embodiment uses the result of the algorithm model monitoring value * comprehensive coefficient to characterize the content of such impurities. The comprehensive coefficient can be set in the range of 1 and 3.6.

[0067] In another preferred embodiment of the above-mentioned method for online monitoring of denitrification urea quality, the following steps may also be included:

[0068] Store impurity content results and comparison results.

[0069] Specifically, historical data can be stored, including: date, time, conductivity, temperature, monitoring results, calibration records, etc.

[0070] Those skilled in the art will appreciate that the following steps may also be included: transmitting the impurity content results and comparison results to a centralized control room for real-time monitoring by production personnel, thereby facilitating timely detection and timely processing of abnormal situations to prevent the abnormal situations from becoming more serious.

[0071] In addition, the above method can also use the density meter monitoring signal as an auxiliary monitoring means. The judgment of abnormal quality of denitrification urea can also set the control value in a graded manner to achieve graded early warning. The measurement range of the conductivity meter used can be 0.1μS / cm~500MS / cm, the automatic measurement reference temperature is 25℃, the solution temperature is measured and compensated, the online monitoring device can set the control temperature through PLC, generally within the range of 45~60℃, and the temperature deviation is controlled within ±2℃. The laboratory monitoring device can set the control temperature through PLC, generally within the range of 25~35℃, and the temperature deviation is controlled within ±2℃.

[0072] In summary, the above method can quickly and accurately monitor the content of impurities mixed in urea, discover urea quality problems in time, strictly control urea acceptance, and avoid urea quality problems affecting the normal operation of denitrification and endangering equipment safety. The above method is very reliable, the monitoring and calibration are simple and easy, and the operation and maintenance workload is small. It can make up for the shortcomings of the existing monitoring methods such as small sampling volume, long monitoring time, difficult operation, and large acceptance workload, and can meet the requirements of production personnel for real-time monitoring of urea quality.

[0073] An embodiment of an online monitoring device for denitrification urea quality provided by the present invention is as follows: Figure 2 and Figure 3 As shown, Figure 2 This is an overall schematic diagram of an embodiment of an online monitoring device for denitrification urea quality provided by the present invention. Figure 3A schematic diagram of the composition of an industrial computer of an online monitoring device for denitrification urea quality provided by the present invention, the device comprises a measuring cell 4 installed in parallel with an outlet pipeline 3 of a urea dissolving pump through an inlet isolation door 1 and an outlet isolation door 2, a sensor 5 extending into the measuring cell 4, the sensor 5 is used to obtain the conductivity and temperature of the denitrification urea solution, the other end of the sensor 5 is connected to an industrial computer 6, the industrial computer 6 comprises a processing unit 601 for data processing and correction, a programmable PLC can be used to process and correct the conductivity of the urea solution measured online continuously, and a calculation unit 602 is also included for calculating the conductivity using an algorithm model to obtain the impurity content result characterized by inorganic salts. It is clear that the algorithm model can be a model after calibration and verification, the inorganic salt can be but not limited to potassium salt and ammonium salt, etc., and a comparison component 603 for comparing the impurity content result with the impurity content warning value to obtain a comparison result and a judging component 604 for judging the quality of denitrification urea according to the comparison result. When the impurity content result does not exceed the impurity content warning value, the comparison result is normal, and when the impurity content exceeds the impurity content warning value, the comparison result is abnormal. When the impurity content exceeds the impurity content warning value, it is proved that the quality of denitrification urea is unqualified, and the higher the impurity content, the lower the quality of denitrification urea, which realizes rapid, timely and reliable early warning monitoring of the quality of denitrification urea.

[0074] During the specific operation, the correction program, algorithm model, evaluation program and alarm program are first established in the PLC, and then the algorithm model is calibrated and verified, and then the conductivity of the urea solution is measured and the conductivity is corrected. Then, the corrected conductivity is input into the algorithm model, and the algorithm model calculates the impurity content, judges whether the impurity content exceeds the warning value, and finally outputs the impurity content and the evaluation result.

[0075] The above-mentioned online monitoring device is installed in parallel on the outlet pipeline of the urea dissolution pump. The urea solution from the urea dissolution pump enters the online monitoring device from the inlet isolation door 3, enters from the bottom liquid inlet of the measuring cell 4, is continuously measured by the sensor 5, and is discharged from the upper liquid outlet of the measuring cell 4. After passing through the outlet pipeline of the monitoring device and the isolation door 2, it enters the outlet main pipeline of the urea dissolution pump and returns to the urea dissolution pump. The calibration of the online monitoring device is a multi-point calibration (at least 3 points), and the calibration range is generally 0-5%. The calibration is performed according to the calibration screen displayed on the touch screen of the industrial computer 6, and the calibration results are automatically stored and participate in the model calculation. The setting of the online monitoring device is performed through the setting screen of the industrial computer 6, including the temperature upper limit setting, impurity content alarm value setting, measurement temperature setting, temperature compensation, correction and calibration parameter setting, etc. The online monitoring device provides a touch screen and a remote monitoring screen display. The touch screen of the industrial computer 6 displays the impurity content, measurement temperature, start and stop status of the temperature control module, related alarm signals, etc. The industrial computer DCS transmits the impurity content and related alarm signals to the production monitoring screen remotely. When the above device is used in the laboratory, it is mostly the same as the online method, but there are some differences: (1) The monitoring personnel first weigh a certain amount of urea sample, add deionized water and stir to dissolve, prepare a certain concentration of urea solution to be tested (generally 25%), and pour the solution into the measurement cell for monitoring; (2) DCS remote display is not performed; (3) The control temperature is different.

[0076] The above-mentioned device can fully consider the properties and influences of different impurity ions, quickly, timely and reliably monitor the content of impurities mixed in denitrification urea, strictly control the quality of urea, discover quality problems in time, and ensure the safe operation of the denitrification system.

[0077] In a specific embodiment of the above-mentioned denitrification urea quality online monitoring device, continue to refer to Figure 2 The industrial computer 6 may further include a temperature control component 605 for controlling the measurement temperature to eliminate the influence of the difference between the measurement temperature and the temperature during calibration.

[0078] The online monitoring device can set the control temperature through PLC, generally within the range of 45-60℃, and the temperature deviation is controlled within ±2℃. The laboratory monitoring device can set the control temperature through PLC, generally within the range of 25-35℃, and the temperature deviation is controlled within ±2℃.

[0079] In another specific embodiment of the above-mentioned denitrification urea quality online monitoring device, the industrial computer 6 may further include an alarm component for sending an alarm signal when the impurity content result exceeds the impurity content warning value.

[0080] Specifically, according to the requirements for industrial urea in GB / T 2440-2017 Urea, the main quality indicator total nitrogen (N) is ≥46.0%, and the purity of urea for denitrification should reach 98.6% or more, that is, the content of other impurities should not be greater than 1.4%, which is the maximum value of the impurity content. For safety reasons, this embodiment uses this maximum value * safety factor as a warning value to judge the quality of urea.

[0081] It should also be noted that, in addition to being used for online installation, the above device can also be used independently in a laboratory.

[0082] The above device is described below with a specific example:

[0083] like Figure 4 As shown, Figure 4 The schematic diagram of a specific example of an industrial computer includes 7 functional modules, including a measurement module 401, a temperature control module 402, a power module 403, a human-computer interaction module 404, a data storage module 405, a PLC module 406, and a DCS remote signal interface 407. The main functions of each module are described as follows: the measurement module 401 is used to measure the conductivity and temperature of the urea solution, and input the measurement signal to the PLC module; the temperature control module 402 is used to control the measurement temperature to eliminate the influence of the difference between the measurement temperature and the temperature during calibration. The temperature control module accepts PLC control. When the temperature deviates from the set value, the PLC sends a control signal to the power module to turn on the temperature control module; the power module 403 is used to supply power to the device, including PLC, human-computer interaction module, temperature control module, etc. The power module accepts PLC control. The control signal is sent to the control module, and the operation and shutdown status signals are output to the human-machine interaction module for display; the human-machine interaction module 404 is used for operation and display, and the operation includes inputting parameters to the PLC, calibrating the monitoring model, and querying data, and the display includes date, time, monitoring results, alarm, temperature, temperature control start and stop status, calibration screen, etc.; the data storage module 405 is used to store historical data, including date, time, conductivity, temperature, monitoring results, calibration records, etc.; the PLC module 406 is the core of the entire device, which contains the algorithms and control programs required for monitoring, including background correction program, calibration program, algorithm model and parameters, temperature control program, evaluation program, alarm program, etc.; the DCS remote signal interface 407 can transmit the monitoring and evaluation results of the online monitoring device to the centralized control room for real-time monitoring by production personnel.

[0084] The communication connection and cooperative operation relationship between each module are described as follows: PLC module 406 receives signal input from measurement module 401, including conductivity and temperature. The conductivity is calibrated and the impurity content is calculated by the built-in algorithm model; the temperature signal received by PLC module 406 is used for conductivity temperature compensation calculation, and outputs a temperature control signal to power module 403 through a constant temperature control program, and achieves a constant temperature of ±2°C through temperature control module 402; PLC module 406 receives parameter setting input from human-computer interaction module 404, including temperature parameters, model parameters, calibration parameters, alarm parameters, data query display, etc.; PLC module 406 outputs monitoring results, alarms and other signals to human-computer interaction module 404, and transmits them to production personnel through DCS remote transmission interface 407; data storage module 405 receives and stores input signals from PLC module 406 and human-computer interaction module 404, and accepts data query and export from PLC module 406 and human-computer interaction module 404.

[0085] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for online monitoring of denitrification urea quality, characterized in that: include: Obtain the conductivity of the denitrification urea solution, and perform data processing and correction; The conductivity is calculated using an algorithm model to obtain an impurity content result characterized by inorganic salts; Comparing the impurity content result with the impurity content warning value to obtain a comparison result; According to the comparison results, the quality of the denitrification urea is judged; Before calculating the conductivity using the algorithm model, the method further includes: After determining the monitoring environment and conditions, the algorithm model is calibrated, verified and debugged at multiple points using a chloride standard solution, multiple groups of sample data are obtained, and the parameters of the algorithm model are evaluated, debugged and verified. The algorithm model is a multiple linear regression curve. The mathematical expression of the algorithm model is: Y=β0+β1X 1i +β2X 2i +m i ,i=1,2,…n, Wherein, Y is conductivity, μS / cm; β0 is the intercept of the regression curve; β1 is the partial regression coefficient 1, which characterizes the influence of the change of impurity content in urea on the conductivity; β2 is the partial regression coefficient 2, which characterizes the influence of the change of urea conductivity over time on the conductivity; X1 is the impurity content, unit is %; X2 is the time, unit is min, starting from t1; μ is the random error, unit is μS / cm.

2. The method for online monitoring of denitrification urea quality according to claim 1, characterized in that: After judging the quality of denitrification urea, the following steps are also included: When the impurity content result exceeds the impurity content warning value, an alarm signal is issued.

3. The method for online monitoring of denitrification urea quality according to claim 1, characterized in that: The data processing and correction include: The conductivity of the denitrification urea solution is differentiated and compared with an input set value to determine a correction value of the conductivity of the urea solution.

4. The method for online monitoring of denitrification urea quality according to claim 1, characterized in that: Also includes: The impurity content result is characterized by multiplying the algorithm model monitoring value by the comprehensive coefficient, wherein the comprehensive coefficient ranges between 1 and 3.6; The impurity content result and the comparison result are displayed.

5. The method for online monitoring of denitrification urea quality according to claim 1, characterized in that: Also includes: The impurity content result and the comparison result are stored.

6. The method for online monitoring of denitrification urea quality according to any one of claims 1 to 5, characterized in that: Also includes: The impurity content result and the comparison result are transmitted to a centralized control room for real-time monitoring by production personnel.

7. A denitrification urea quality online monitoring device, characterized in that: The method for online monitoring the quality of denitrification urea as described in any one of claims 1 to 6 comprises a measuring cell installed in parallel with an outlet pipeline of a urea dissolution pump through an inlet isolation door and an outlet isolation door, a sensor extending into the measuring cell, the sensor being used to obtain the conductivity and temperature of the denitrification urea solution, the other end of the sensor being connected to an industrial computer, the industrial computer comprising a processing unit for data processing and correction, a calculation unit for calculating the conductivity using an algorithm model to obtain an impurity content result characterized by inorganic salts, a comparison unit for comparing the impurity content result with an impurity content warning value to obtain a comparison result, and an evaluation unit for evaluating the quality of the denitrification urea according to the comparison result.

8. The denitrification urea quality online monitoring device according to claim 7, characterized in that: The industrial computer also includes a temperature control component for controlling the measurement temperature to eliminate the influence of the difference between the measurement temperature and the temperature during calibration.

9. The denitrification urea quality online monitoring device according to claim 7, characterized in that: The industrial computer also includes an alarm component for sending an alarm signal when the impurity content result exceeds the impurity content warning value.

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