Self-cleaning and early warning control system for CEMS sampling device of thermal power generating unit

Abstract

The utility model relates to a self-cleaning and early-warning control system for a CEMS sampling device of a thermal power generating unit. The self-cleaning and early-warning control system comprises a sampling probe, an analysis instrument cabinet and a drainage tank, one end of the sampling probe is connected with the flue, and the other end is connected with an inlet of the analysis instrument cabinet through a sampling pipeline; a sampling main pipeline of the analysis instrument cabinet is sequentially provided with an impurity separator, an isolation electromagnetic valve, a primary cooler, a secondary cooler, a micro-pressure measurement module, a sampling pump, a three-position electromagnetic valve and an analysis unit along the direction from an inlet to an outlet; and an outlet of the analysis instrument cabinet is connected with the drainage tank. The self-cleaning system has the advantages that the micro-pressure measuring module is arranged, whether system self-cleaning needs to be carried out or not can be judged according to gas path pressure, the self-cleaning frequency is effectively shortened, and the effective utilization rate of denitration and desulfurization system equipment and environment-friendly parameter continuity are improved; hidden dangers of the CEMS system can be effectively eliminated, and early warning and self-cleaning can be carried out before an accident expands.

Description

Technical Field

[0001] The utility model relates to the field of thermal power generation control, and more specifically, it relates to a self-cleaning and early warning control system for a CEMS sampling device of a thermal power unit. Background Art

[0002] For thermal power generating units, a large amount of gaseous nitrogen oxides and sulfides generated during the production process cannot be directly discharged into the atmosphere. They must undergo desulfurization and denitrification processes and can only be discharged into the atmosphere after passing the detection.

[0003] The Continuous Emission Monitoring System (CEMS) is a necessary condition for the normal operation of environmental protection equipment. The current CEMS sampling system is maintained by daily inspection combined with regular purging. Regular purging is to clean the scale and ash accumulation in the system. However, the temperature drop caused by purging with compressed air is likely to cause the condensation of flue gas to generate nitrate and sulfate impurities. Therefore, regular and timed purging has the disadvantages of untimely or excessive maintenance, and it cannot predict the actual state of the CEMS in time, resulting in an increasing failure rate of the CEMS equipment. Subsequently, it affects the normal operation of the desulfurization and denitrification processes. Therefore, the manual maintenance mode that only relies on experience and appearance to judge whether the system is operating normally cannot meet the environmental protection requirements. Content of the Utility Model

[0004] The purpose of the utility model is to overcome the deficiencies of the prior art and propose a self-cleaning and early warning control system for a CEMS sampling device of a thermal power unit, including: a sampling probe, an analytical instrument cabinet, and a drainage tank;

[0005] Among them, one end of the sampling probe is connected to the flue, and the other end is connected to the inlet of the analytical instrument cabinet through a sampling pipeline; the sampling main pipeline of the analytical instrument cabinet is sequentially provided with an impurity separator, an isolation solenoid valve, a primary cooler, a secondary cooler, a micro-pressure measurement module, a sampling pump, a three-way solenoid valve, and an analysis unit along the direction from the inlet to the outlet; the outlet of the analytical instrument cabinet is connected to the drainage tank.

[0006] Preferably, the impurity separator is composed of a first three-way joint, an isolation valve, and a sundries storage bottle. The first three-way joint and the sundries storage bottle are respectively arranged at both ends of the isolation valve; the first three-way joint is arranged on the sampling main pipeline and is used to connect the inlet of the analytical instrument cabinet, the isolation solenoid valve, and the isolation valve respectively.

[0007] Preferably, the diameter of the end of the first three-way joint connected to the isolation valve is larger than the diameters of the other two ends.

[0008] Preferably, a check valve is arranged at the bottle mouth of the sundries storage bottle.

[0009] Preferably, the micro-pressure measurement module consists of a second three-way joint and a micro-pressure measurement unit; the second three-way joint is arranged on the sampling main pipeline and is used to connect the secondary cooler, the sampling pump and the micro-pressure measurement unit respectively.

[0010] Preferably, a tracing cable is laid on the sampling pipeline.

[0011] Preferably, the primary cooler is also connected to the drainage tank through a primary peristaltic pump; the secondary cooler is also connected to the drainage tank through a secondary peristaltic pump.

[0012] The beneficial effects of the present utility model are as follows:

[0013] 1. By setting up the micro-pressure measurement module, the present utility model can judge whether system self-cleaning is required according to the gas path pressure. Compared with the system's regular self-cleaning, it can not only effectively shorten the self-cleaning frequency, improve the effective utilization rate of the denitration and desulfurization system equipment and the continuity of environmental protection parameters, and prevent environmental protection over-standard events; but also effectively eliminate the hidden dangers of the CEMS system and give early warnings and self-cleaning before the accident expands.

[0014] 2. By setting up the impurity separator, the present utility model can automatically collect the impurities in the CEMS sampling pipeline. The maintenance and cleaning of the impurity separator do not require the CEMS sampling system to exit operation. The impurity cleaning is completed while the system is self-cleaning, and it is no longer necessary for the operation and maintenance personnel to separately exit the system to regularly clean the pipeline impurities, which can improve the continuity and accuracy of CEMS data. Description of the Drawings

[0015] Figure 1 It is a structural schematic diagram of the self-cleaning and early warning control system for the CEMS sampling device of a thermal power unit;

[0016] Description of the reference numerals: sampling probe 1, analysis instrument cabinet 2, impurity separator 3, isolation solenoid valve 4, primary cooler 5, secondary cooler 6, micro-pressure measurement module 7, sampling pump 8, three-way solenoid valve 9, analysis unit 10, drainage tank 11, primary peristaltic pump 12, secondary peristaltic pump 13, water blocking device 14, filter 15, probe purging interface 16. Detailed Embodiments

[0017] The following further describes the present utility model in conjunction with embodiments. The description of the following embodiments is only used to help understand the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present utility model, several modifications can still be made to the present utility model, and these improvements and modifications also fall within the protection scope of the claims of the present utility model.

[0018] The sampling pump extracts the flue gas in the flue through air extraction and sends it into the CESM analysis instrument cabinet. To prevent the sampling pipeline from cooling down after leaving the flue, forming condensation to generate sulfates and hydrochlorides that block the sampling channel, a tracing cable is laid during the transportation of the sampled gas to keep the flue gas temperature at 140 degrees. After being extracted to the analysis cabinet, it goes through primary cooling, secondary cooling, the sampling pump, and a water arrester, and then enters the flue gas analysis unit for analysis. Since the analysis unit is a precision instrument and requires a good measurement environment, it is required that there are no impurities such as water, sulfates, and nitrates in the gas path after the sampling pump. Otherwise, it will cause pollution in the gas chamber of the sampling unit, resulting in pollution and damage to the analysis unit. Once the analysis unit is polluted, it cannot be repaired, and the procurement cost is generally about 200,000 yuan. Therefore, the CEMS sampling system is set with a self-purging function to clean the filter element at the sampling probe and the impurities in the sampling pipeline. Usually, the CEMS device is factory-set to perform a cleaning purge once every 8 hours, and the purge duration is 15 minutes. After the purge signal is triggered, the isolation solenoid valve is closed, and the probe purge solenoid valve is opened to clean the sampling probe and the sampling pipeline to remove the impurities in the pipeline, ensuring that the analysis unit is in a safe and reliable operating environment.

[0019] However, currently, the CEMS sampling system is generally set to self-purge every 8 hours. When the system is just put into operation, the environment is good without scaling and ash accumulation. The 8-hour self-purge is an over-maintenance situation. The denitration and desulfurization systems are mainly controlled based on the concentrations of nitrogen oxides and sulfides measured by the analysis unit. The over-maintenance of the CEMS will lead to a long system exit time and high frequency. Without data reference for the desulfurization and denitration equipment, it is easy to cause environmental protection over-standard events if the control system is not timely after maintenance. At the same time, the long-term abnormal state of the environmental protection data will affect the authenticity and continuity of the data, and even lead to accountability by the environmental protection bureau according to laws and regulations.

[0020] Moreover, after the CEMS system has been in operation for a long time, the sampling equipment is aging and deteriorating. The 8-hour self-purge has the situation of improper and untimely maintenance. It is simply impossible to accurately judge whether immediate maintenance is needed during daily inspections. When the system fails, the entire process from discovery, preparation, maintenance to recovery has a long cycle, and the efficiency is even lower at night.

[0021] In addition, during the self-purge process of the existing CEMS sampling system, some impurities in the analysis instrument cabinet cannot be detected and the impurities in the pipeline cannot be cleaned.

[0022] To solve the above problems, as an embodiment, the present application provides a self-cleaning and early warning control system for the CEMS sampling device of a thermal power unit, which cleans the impurities in the pipeline during the purge process, and finally realizes the stable and reliable operation of the CEMS sampling, the normal operation of the denitration and desulfurization systems, and the compliance of environmental protection parameters.

[0023] As Figure 1As shown in the figure, the self-cleaning and early warning control system for the CEMS sampling device of a thermal power unit includes: a sampling probe 1, an analytical instrument cabinet 2, and a drainage tank 11;

[0024] Among them, one end of the sampling probe 1 is connected to the flue, and the other end is connected to the inlet of the analytical instrument cabinet 2 through a sampling pipeline; along the direction from the inlet to the outlet of the sampling main pipeline of the analytical instrument cabinet 2, an impurity separator 3, an isolation solenoid valve 4, a primary cooler 5, a secondary cooler 6, a micro-pressure measurement module 7, a sampling pump 8, a three-way solenoid valve 9, and an analysis unit 10 are sequentially arranged; the outlet of the analytical instrument cabinet 2 is connected to the drainage tank 11.

[0025] The impurity separator 3 is composed of a first three-way joint, an isolation valve, and a debris storage bottle. The first three-way joint and the debris storage bottle are respectively arranged at both ends of the isolation valve; the first three-way joint is arranged on the sampling main pipeline and is used to connect the inlet of the analytical instrument cabinet 2, the isolation solenoid valve 4, and the isolation valve respectively. The isolation valve is set to be normally open during system operation. When maintenance personnel clean impurities regularly, the isolation valve is closed, and the storage bottle is removed to clean the debris, and then the system is restored.

[0026] The diameter of the end of the first three-way joint connected to the isolation valve is larger than the diameters of the other two ends. For example, the ratio of the diameter of the end connected to the isolation valve to the diameter of any one of the other two ends is 6:4, and impurities can be preferentially blown into the impurity separator during the purging process.

[0027] A check valve is arranged at the bottle mouth of the debris storage bottle. When the system performs self-cleaning, compressed air opens the check valve, and when the system is running, the suction force and spring force inside the system seal the bottle mouth.

[0028] The micro-pressure measurement module 7 is composed of a second three-way joint and a micro-pressure measurement unit; the second three-way joint is arranged on the sampling main pipeline and is used to connect the secondary cooler 6, the sampling pump 8, and the micro-pressure measurement unit respectively. The micro-pressure measurement module 7 is used to monitor whether the gas path of the sampling pipeline is unobstructed.

[0029] A heating cable is laid on the sampling pipeline.

[0030] The primary cooler 5 is also connected to the drainage tank 11 through a primary peristaltic pump 12; the secondary cooler 6 is also connected to the drainage tank 11 through a secondary peristaltic pump 13.

Claims

1. A self-cleaning and early warning control system for a CEMS sampling device of a thermal power unit, characterized in that: It comprises: a sampling probe (1), an analytical instrument cabinet (2) and a drainage tank (11); One end of the sampling probe (1) is connected to the flue, and the other end is connected to the inlet of the analytical instrument cabinet (2) through a sampling pipeline; the main sampling pipeline of the analytical instrument cabinet (2) is provided with an impurity separator (3), an isolation solenoid valve (4), a primary cooler (5), a secondary cooler (6), a micro-pressure measurement module (7), a sampling pump (8), a three-position solenoid valve (9) and an analysis unit (10) in sequence from the inlet to the outlet; the outlet of the analytical instrument cabinet (2) is connected to a drainage tank (11).

2. The self-cleaning and early warning control system for the CEMS sampling device of a thermal power plant according to claim 1, characterized in that: The impurity separator (3) is composed of a first three-way joint, an isolation valve and a debris storage bottle, wherein the first three-way joint and the debris storage bottle are respectively arranged at both ends of the isolation valve; the first three-way joint is arranged on the sampling main line, and is used to respectively connect the inlet of the analytical instrument cabinet (2), the isolation solenoid valve (4) and the isolation valve.

3. The self-cleaning and early warning control system for the CEMS sampling device of a thermal power plant according to claim 2, characterized in that: The pipe diameter at the end of the first three-way joint connected to the isolation valve is larger than the pipe diameters at the other two ends.

4. The self-cleaning and early warning control system for the CEMS sampling device of a thermal power plant according to claim 3, characterized in that: The bottle mouth of the sundries storage bottle is provided with a check valve.

5. The self-cleaning and early warning control system for the CEMS sampling device of a thermal power plant according to claim 4, characterized in that: The micro-pressure measurement module (7) is composed of a second three-way joint and a micro-pressure measurement unit; the second three-way joint is arranged on the main sampling line and is used to respectively connect the secondary cooler (6), the sampling pump (8) and the micro-pressure measurement unit.

6. The self-cleaning and early warning control system for the CEMS sampling device of a thermal power plant according to claim 5, characterized in that: A heating cable is laid on the sampling pipeline.

7. The self-cleaning and early warning control system for the CEMS sampling device of a thermal power plant according to claim 6, characterized in that: The primary cooler (5) is also connected to the drainage tank (11) via a primary peristaltic pump (12); and the secondary cooler (6) is also connected to the drainage tank (11) via a secondary peristaltic pump (13).

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