On-line monitoring system and method for trace elements in desulfurization tower slurry

Abstract

The application discloses a kind of desulfurization tower slurry trace element on-line monitoring system and method, including limestone slurry and absorption liquid sampling module, limestone slurry and absorption liquid pretreatment module, sample analysis detection module, early warning module;Limestone slurry and absorption liquid sampling module are used to collect limestone slurry and absorption liquid sample from desulfurization tower;Limestone slurry and absorption liquid pretreatment module are used to the limestone slurry and absorption liquid sample are pretreated, to obtain sample to be measured;Sample analysis detection module is used to detect analysis to the sample, to determine the kind and mass percentage content of trace element contained in the limestone slurry and absorption liquid;Early warning module is used to the mass percentage content of trace element abnormal value is early warning operation.The application effectively prevents sample pollution to affect result, scanning speed is fast, linear range is wide, stability is good, and analysis efficiency is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of solid-liquid mixed sample heavy metal online monitoring, in particular to a desulfurization tower slurry trace element online monitoring system and method. BACKGROUND

[0002] The wet flue gas desulfurization technology is mature, suitable for large-capacity units, and has the advantages of stable system operation, wide adaptability to coal types and unit load changes, fast desulfurization reaction speed, and comprehensive utilization of desulfurization by-products such as gypsum. It is widely used in coal-fired power plant units. A large number of chemical reactions occur in the wet flue gas desulfurization system, the composition of the absorption liquid is complex, and the recirculation of the gypsum slurry can lead to the enrichment of some trace elements. This concentration can affect the normal operation of the desulfurization system, causing a decrease in desulfurization efficiency. In addition, a large amount of trace elements in the absorption liquid can enter the environment with the discharge of desulfurization gypsum and wastewater, becoming an environmental safety hazard. Online monitoring of the content of trace elements in the limestone slurry entering the desulfurization tower and the absorption liquid in the desulfurization tower can monitor the stability of the desulfurization tower operation. When the content of trace elements is abnormal, an early warning is given, and the management personnel can timely adjust and control to prevent the problem from worsening. At the same time, when problems such as bubbling and slow reaction occur in the desulfurization tower, online monitoring of the content of trace elements can provide a basis for determining the cause of the problem.

[0003] Currently, online monitoring technology for trace elements in water and solids is being gradually developed. X-ray fluorescence method is widely used in the detection of element content in solid samples, and has the advantages of simple operation, fast scanning speed, wide linear range, good stability, and high analysis efficiency. The X-ray fluorescence method has a portable monitoring device and is mainly used for solid detection. There is no online monitoring technology using this method for solid-liquid mixed samples. The absorption liquid and limestone slurry in the desulfurization tower are solid-liquid mixed samples, which have complex composition and are difficult to digest. In order to further meet the specific application requirements of online monitoring of trace elements in the absorption liquid and limestone slurry in the desulfurization tower, it is necessary to establish a more emerging and reliable real-time online monitoring technology. SUMMARY

[0004] In view of the defects in the prior art, the present application provides a desulfurization tower slurry trace element online monitoring system and method for solid-liquid mixed samples.

[0005] The technical scheme adopted by the present application is:

[0006] The desulfurization tower slurry trace element online monitoring method comprises the following steps:

[0007] Step S1: Collecting limestone slurry or desulfurization slurry from the desulfurization tower, and guiding the obtained slurry into a conical container and stirring uniformly;

[0008] Step S2: The slurry in the conical container is guided into a dry grinder for pretreatment, and after drying and grinding, the sample is sent to a sample disc for pressing to obtain a sample to be tested;

[0009] Step S3: The sample to be tested is sent to a sample analysis and detection module to obtain the types and percentage contents of trace elements.

[0010] Step S4: According to the types and percentage contents of trace elements, the 6-SIGMA criterion is used to judge the elements with abnormal percentage contents, and the abnormal values are prewarned.

[0011] Further, in step S4, based on the differences in different unit groups of smoke dust, limestone and water quality, the percentage contents of trace elements in limestone slurry and absorption liquid during stable operation of each desulfurization tower are collected to obtain a data set; the data set is subjected to abnormal value elimination to obtain a normal value data set; the online monitoring result is subjected to abnormal value judgment, and if the percentage content of trace elements is determined as an abnormal value, a prewarning is given; for data set processing and abnormal value judgment, it specifically includes:

[0012] First, build a data set, assuming that the data set is [X1, X2, X3···X n ], eliminate abnormal values using the six sigma method, calculate the standard deviation σ of the data set, and data points outside the six standard deviation range are determined as abnormal values. The abnormal data in the data set is removed to obtain a normal value data set [N1, N2, N3···N n ];

[0013]

[0014] Second, use the Isolation Forest to monitor the abnormality of the value, randomly select a value between the maximum and minimum values of the normal value data set [N1, N2, N3···N n ] to divide the data points; the division of the observation value is recursively repeated until all observation values are isolated; after obtaining the isolated tree, the generated isolated tree is used to evaluate the test data, and the abnormal score s is calculated; for each sample X, the abnormal score is calculated by the formula:

[0015]

[0016]

[0017] h(x): the path length of the sample on the tree;

[0018] E(h(x)): the average path length of the sample on the tree;

[0019] is the standardization processing of the path length h(x) of the sample x;

[0020] The exponential part value range is (-∞, 0), so the s value range is (0, 1); the smaller the path length is, the closer s is to 1, and the greater the probability that the sample is an abnormal value is; when the abnormal score of a normal sample is close to 1, the sample is judged as an abnormal sample, and vice versa.

[0021] An online monitoring system for trace elements in a desulfurization tower slurry, characterized in that it comprises a limestone slurry and absorption liquid sampling module, a limestone slurry and absorption liquid pretreatment module, a sample analysis and detection module, and a warning module; wherein,

[0022] The limestone slurry and absorption liquid sampling module is used to collect limestone slurry and absorption liquid samples from the desulfurization tower;

[0023] The limestone slurry and absorption liquid pretreatment module is used to pretreat the limestone slurry and absorption liquid samples, thereby obtaining samples to be tested;

[0024] The sample analysis and detection module is used to detect and analyze the samples, thereby determining the types and mass percentage contents of trace elements contained in the limestone slurry and absorption liquid;

[0025] The warning module is used to perform a warning operation on abnormal values of the mass percentage contents of trace elements.

[0026] Further, the limestone slurry and absorption liquid sampling module specifically comprises a conical container, the upper end inlets of the conical container are connected to the limestone slurry outlet and the absorption liquid outlet of the desulfurization tower through delivery pipes, respectively, and the delivery pipes are respectively provided with on-off valves; a stirring device is built-in the conical container, and an outlet is arranged at the bottom of the conical container for connecting the limestone slurry and absorption liquid pretreatment module.

[0027] Further, the limestone slurry and absorption liquid pretreatment module comprises a dry grinder, an inclined pipeline, and a sample disc, the top inlet of the dry grinder is connected to the bottom outlet of the conical container, an inclined pipeline is arranged at the bottom end outlet of the dry grinder, and a sample disc is arranged at the lower end connection of the inclined pipeline; a tablet press is arranged above the sample disc, and a conveyor belt is arranged below the sample disc; the tested sample after being pressed by the sample disc is conveyed to the sample analysis and detection module by the conveyor belt.

[0028] Further, the sample analysis detection module comprises an X-ray atomic fluorescence spectrometer, the early warning module comprises a computer terminal, and a computer data processing software is built in the computer terminal; the X-ray atomic fluorescence spectrometer is connected with the computer terminal; the X-ray atomic fluorescence spectrometer excites atoms in a to-be-tested substance by using primary X-ray photons to make the atoms generate fluorescent X-rays; the computer data processing software determines the types of trace elements by measuring the energy of characteristic X-rays and determines the content of trace elements according to the intensity of the characteristic X-rays; according to the statistical result of the computer data processing software, the types and percentage contents of trace elements in the limestone slurry and the absorption liquid in the desulfurization tower in a specific time period are displayed, the types and percentage content values of trace elements are evaluated, and corresponding early warning operations are performed when the values exceed the limit values.

[0029] The switch valve is connected with a timing device, is opened for 10s and then closed, and is opened again after the detection result is displayed.

[0030] The present application has the following beneficial effects:

[0031] 1) Compared with other heavy metal detection methods such as inductively coupled plasma mass spectrometry and atomic absorption spectrometry, the X-ray fluorescence method does not need to perform digestion treatment on the sample, effectively prevents sample pollution from affecting the result, has fast scanning speed, wide linear range, good stability and high analysis efficiency.

[0032] 2) The early warning module can monitor the running stability of the desulfurization tower, and early warning is performed when the content of trace elements is abnormal; the result data set is subjected to outlier rejection by using a six-sigma method, and outlier judgment is performed by using an isolated forest, so that the accuracy of outlier judgment is improved. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Structure schematic diagram of the desulfurization tower slurry trace element online monitoring system;

[0034] Figure 2 Schematic diagram of a desulfurization tower slurry trace element online monitoring process. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in a clear and complete manner in combination with the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0036] Embodiment 1

[0037] The above examples are only used to illustrate the technical solutions of the present application, but not limit the same; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalent ones; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

[0038] Figure 1 The structure of the desulfurization tower slurry microelement on-line monitoring system is schematically shown, which comprises a limestone slurry and absorption liquid sampling module, a limestone slurry and absorption liquid pretreatment module, a sample analysis and detection module, and a warning module.

[0039] The limestone slurry and absorption liquid sampling module is used to collect limestone slurry and absorption liquid samples from the desulfurization tower; the limestone slurry and absorption liquid sampling module specifically comprises a conical container 1, the upper end inlets of the conical container 1 are connected with the limestone slurry outlet 4 and the absorption liquid outlet 5 of the desulfurization tower 3 through conveying pipes 2 respectively, and the conveying pipes 2 are respectively provided with on-off valves 6, the on-off valves 6 are connected with timing devices, are opened for 10 seconds and then closed, and are opened again after the detection results are displayed; the conical container 1 is internally provided with a stirring device, and the bottom of the conical container 1 is provided with an outlet for connecting with the limestone slurry and absorption liquid pretreatment module.

[0040] The limestone slurry and absorption liquid pretreatment module is used to pretreat the limestone slurry and absorption liquid samples, so as to obtain samples to be detected; the limestone slurry and absorption liquid pretreatment module comprises a drying grinder 7, an inclined pipeline 8, and a sample disc 9, the top inlet of the drying grinder 7 is connected with the bottom outlet of the conical container 1, the bottom outlet of the drying grinder 7 is provided with the inclined pipeline 8, and the lower end of the inclined pipeline 8 is provided with the sample disc 9; the sample disc 9 is provided with a tablet press above, and is provided with a conveying belt 10 below; the sample to be detected after being pressed by the sample disc 9 is conveyed to the sample analysis and detection module through the conveying belt 10.

[0041] The sample analysis and detection module is used to detect and analyze the samples, so as to determine the types and mass percentage contents of the microelements contained in the limestone slurry and absorption liquid; the warning module is used to perform a warning operation on the abnormal values of the mass percentage contents of the microelements.

[0042] The sample analysis detection module comprises an X-ray atomic fluorescence spectrometer 11, and the early warning module comprises a computer terminal 12, wherein a computer data processing software is built in the computer terminal 12; the X-ray atomic fluorescence spectrometer 11 is connected with the computer terminal 12; the X-ray atomic fluorescence spectrometer 11 excites atoms in a to-be-detected sample by using primary X-ray photons to make the atoms generate fluorescent X-rays; the computer data processing software determines the types of trace elements by measuring the energy of characteristic X-rays and determines the content of trace elements according to the intensity of the characteristic X-rays; according to the statistical result of the computer data processing software, the types and percentage contents of trace elements in the limestone slurry and the absorption liquid in the desulfurization tower in a specific time period are displayed, the types and percentage contents of trace elements are evaluated, and corresponding early warning operations are performed when the values exceed the limit.

[0043] In order to collect the limestone slurry or desulfurization slurry from the desulfurization tower, the upper end inlets of the conical containers 1 are respectively connected with the limestone slurry outlets 4 and the absorption liquid outlets 5 of the desulfurization tower through the conveying pipes.

[0044] In order to control the collection of the limestone slurry or absorption liquid sample, the on-off valves 6 are respectively arranged on the conveying pipes 2, the on-off valves 6 are connected with the timing devices, are opened for 10 seconds and then closed, and are opened again after the detection result is displayed.

[0045] In order to collect the limestone slurry or desulfurization slurry from the desulfurization tower and fully mix and uniformize the sample, the sample enters the conical containers 1 through the conveying pipes 2 and is stirred to form a uniform sample; the conical containers 1 have bottom outlets and stirring devices, and the stirring devices have an automatic stirring function.

[0046] In order to fully dry and grind the sample into fine particles after the sample enters the dry grinder from the conical container, the bottom outlet of the conical container 1 is opened, and the sample enters the dry grinder 7.

[0047] In order to make the sample enter the sample disc after being dried and ground, the sample enters the sample disc 9 through the inclined pipe 8.

[0048] In order to press the sample into a smooth surface after being dried and ground for X-ray detection, the sample enters the sample disc 9, and a tablet press is arranged above the sample disc 9 to press the to-be-detected sample.

[0049] In order to automatically make the to-be-detected sample enter the detection area of the X-ray instrument, the to-be-detected sample is conveyed to the detection area of the X-ray instrument by the conveying belt.

[0050] In order to perform early warning on the element abnormal value, the computer data processing module displays the types and percentage contents of trace elements in the limestone and absorption liquid in the desulfurization tower in a specific time period according to the statistical result; the types and percentage contents of trace elements are evaluated, and corresponding early warning operations are performed when the values exceed the limit.

[0051] Figure 2The desulfurization tower slurry trace element online monitoring method is schematically shown, including the following steps:

[0052] Step S1: limestone slurry or desulfurization slurry is collected from the desulfurization tower, and the obtained slurry is guided into a conical container and stirred uniformly;

[0053] Step S2: the slurry in the conical container is guided into a dry grinder for pretreatment, and after drying and grinding, it is sent to a sample disc for pressing to obtain a sample to be tested;

[0054] Step S3: the sample to be tested is sent to a sample analysis and detection module, so as to obtain the types and percentage contents of trace elements.

[0055] Step S4: according to the types and percentage contents of trace elements, the 6-SIGMA criterion is used to judge the percentage content of abnormal elements, and the abnormal value is prewarned.

[0056] Based on the differences in flue dust, limestone and water quality of different units, the percentage contents of trace elements in limestone slurry and absorption liquid of each desulfurization tower during stable operation are collected to obtain a data set; the data set is subjected to abnormal value elimination to obtain a normal value data set; the online monitoring result is subjected to abnormal value judgment, and if the percentage content of trace elements is determined as an abnormal value, a prewarning is given; the data set processing and abnormal value judgment specifically include:

[0057] First, build a data set, assuming that the data set is [X1, X2, X3···X n ], eliminate abnormal values by using six sigma method, calculate the standard deviation σ of the data set, and determine the data points outside the six standard deviation range as abnormal values, remove the abnormal data in the data set, and obtain the normal value data set [N1, N2, N3···N n ];

[0058]

[0059] Second, use isolated forest to monitor the abnormality of the value, randomly select a value between the maximum and minimum values of the normal value data set [N1, N2, N3···N n ] to divide the data points. The division of observation values is recursively repeated until all observation values are isolated. After obtaining the isolated tree, the generated isolated tree is used to evaluate the test data, and the abnormal score s is calculated. For each sample X, the abnormal score is calculated by the formula:

[0060]

[0061]

[0062] h(x): the path length of the sample on the tree;

[0063] E(h(x)): the average path length of the sample on the tree;

[0064] is the standardization of the path length h(x) of the sample x.

[0065] The exponential part value range is (-∞, 0), so the s value range is (0, 1). When the path length is smaller, s is closer to 1, and the probability that the sample is an abnormal value is greater. When the abnormal score of the normal sample is close to 1, the sample is judged to be an abnormal sample, and vice versa, it is judged to be a normal sample.

[0066] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art, according to the technical solution and the inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for on-line monitoring of trace elements in desulfurization column slurry, characterized in that, The method comprises the following steps: Step S1: Collecting limestone slurry or desulfurization slurry from a desulfurization tower, and guiding the obtained slurry into a conical container and stirring uniformly; Step S2: Guiding the slurry in the conical container into a dry grinder for pretreatment, and after dry grinding, sending into a sample disc for pressing to obtain a sample to be tested; Step S3: Sending the sample to be tested into a sample analysis and detection module to obtain the types and percentage contents of trace elements; Step S4: According to the types and percentage contents of trace elements, using the 6-SIGMA criterion to judge the percentage content abnormal elements and performing a pre-warning operation on the abnormal values.

2. The method according to claim 1, wherein in step S4, based on the differences in different unit smoke, limestone and water quality, the percentage contents of trace elements in the limestone slurry and the absorption liquid of each desulfurization tower in stable operation are collected to obtain a data set; the data set is subjected to abnormal value elimination to obtain a normal value data set; the online monitoring result is subjected to abnormal value judgment, and if the percentage content of trace elements is determined as an abnormal value, a pre-warning is given; For data set processing and abnormal value judgment, it specifically comprises: The division of observation values is recursively repeated until all observation values are isolated; after obtaining an isolated tree, the generated isolated tree is used to evaluate test data to calculate an abnormal score s; for each sample X, the abnormal score s is calculated by the formula: First, build a data set, assuming the data set is [X1, X2, X3···X n ], using six sigma method to remove outliers, calculate the standard deviation σ of the data set, and the data points outside the six standard deviation range are determined as outliers. Remove the abnormal data in the data set to get the normal value data set [N1, N2, N3···N n ]; Second, the isolated forest is used for monitoring the abnormal value of the abnormal value, and the normal value data set [N1, N2, N3···N n ] is randomly selected to divide the data points between the maximum and minimum values; h(x): the path length of the sample on the tree; E(h(x)): the average path length of the sample on the tree; The exponential part value range is (-∞, 0), so the s value range is (0, 1); the smaller the path length, the closer s is to 1, and the greater the probability that the sample is an abnormal value; when the abnormal score of a normal sample is close to 1, the sample is determined as an abnormal sample, and vice versa. is a standardization of the path length h(x) of the sample x; It comprises a limestone slurry and absorption liquid sampling module, a limestone slurry and absorption liquid pretreatment module, a sample analysis and detection module, and a pre-warning module; wherein 3. An on-line monitoring system for the on-line monitoring method of trace elements in the slurry of a desulphurization tower according to claim 1, characterized in that, The limestone slurry and absorption liquid sampling module is used to collect limestone slurry and absorption liquid samples from a desulfurization tower; The limestone slurry and absorption liquid pretreatment module is used to pretreat the limestone slurry and absorption liquid samples to obtain samples to be tested; The sample analysis and detection module is used to detect and analyze the samples to determine the types and mass percentage contents of trace elements contained in the limestone slurry and absorption liquid; The pre-warning module is used to perform a pre-warning operation on the mass percentage content abnormal values of trace elements; The limestone slurry and absorption liquid sampling module specifically comprises a conical container, the upper end inlets of the conical container are connected with the limestone slurry outlet and the absorption liquid outlet of the desulfurization tower through conveying pipes, respectively, and the conveying pipes are respectively provided with on-off valves connected with a timing device, which is opened for 10 seconds and then closed, and is opened again after the detection result is displayed; the conical container is internally provided with a stirring device, and the bottom of the conical container is provided with an outlet for connecting with the limestone slurry and absorption liquid pretreatment module. ​ 4. The on-line monitoring system of claim 3, wherein: The limestone slurry and absorption liquid pretreatment module comprises a dry grinder, an inclined pipeline and a sample disc, the top inlet of the dry grinder is connected with the bottom outlet of a conical container, the bottom outlet of the dry grinder is provided with the inclined pipeline, and the lower end of the inclined pipeline is provided with the sample disc; a tablet press is arranged above the sample disc, and a conveyor belt is arranged below the sample disc; the measured sample after being pressed by the sample disc is conveyed to the sample analysis and detection module by the conveyor belt.

5. The on-line monitoring system of claim 3, wherein: The sample analysis and detection module comprises an X-ray atomic fluorescence spectrometer, the early warning module comprises a computer terminal, and computer data processing software is built in the computer terminal; the X-ray atomic fluorescence spectrometer is connected with the computer terminal, primary X-ray photons are used to excite atoms in the measured substance by the X-ray atomic fluorescence spectrometer, so that fluorescent X-rays are generated, the computer data processing software determines the type of trace elements by measuring the energy of characteristic X-rays, and the content of trace elements is determined according to the strength of characteristic X-rays; according to the statistical results of the computer data processing software, the types and percentage contents of trace elements in the limestone slurry and absorption liquid in the desulfurization tower in a specific time period are displayed, the types and percentage content values of trace elements are evaluated, and corresponding early warning operations are performed when the values exceed the limit.

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