Urea hydrolysis pollution discharge period and pollution discharge quantity control system and method

Abstract

The invention discloses a urea hydrolysis pollution discharge period and pollution discharge quantity control system and method, and belongs to the technical field of power plant wastewater. The system comprises a pollution discharge unit, a surface pollution discharge unit and a bypass circulation unit, the blowdown unit comprises a blowdown main valve and a blowdown secondary valve; the bypass circulation unit comprises a bypass circulation primary valve, a bypass circulation secondary valve, a bypass blow-down valve and an online analysis device; one end of the blow-down main valve is connected with the urea hydrolysis reactor, the other end of the blow-down main valve is connected with one end of the blow-down secondary valve, and the other end of the blow-down secondary valve is connected with the wastewater pool; one end of the bypass circulation primary valve is arranged between the blow-down main valve and the blow-down secondary valve, and the other end of the bypass circulation primary valve is connected with one end of the bypass circulation secondary valve. Through real-time sampling of the solution and real-time analysis of ions in the solution, the urea hydrolysis pollution discharge period and the pollution discharge amount are controlled, pollution discharge of the hydrolyzer is carried out at proper time and proper amount, normal operation of the hydrolyzer is guaranteed, and waste of the urea solution is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of power plant wastewater, and in particular to a urea hydrolysis sewage discharge cycle and sewage discharge amount control system and method. Background Art

[0002] In the process of coal-fired power plants transforming to more environmentally friendly and efficient energy utilization methods, the application of liquid ammonia to urea technology is undoubtedly an important milestone. Urea is a relatively safe chemical that is easy to store and transport. It produces ammonia through hydrolysis reaction, which provides a stable ammonia source for the denitrification system of power plants, effectively reduces the emission of nitrogen oxides, and is of great significance to environmental protection. However, with the widespread application of this technology, the corrosion, scaling, foaming and other problems exposed by the hydrolyzer during operation have become the key factors restricting its efficient and stable operation.

[0003] The corrosion problem mainly stems from the presence of chloride ions in the hydrolyzer solution. As a strong electrolyte, chloride ions easily form an electrochemical corrosion environment on the metal surface, accelerating the corrosion rate of the hydrolyzer coil. This corrosion will not only cause the wall thickness of the equipment to be thinned and reduce its pressure bearing capacity, but in severe cases it will also cause leakage accidents, threatening the safe production of the power plant. The scaling problem is related to the deposition of insoluble salt substances such as sodium chloride and iron carbonate in the solution. These substances gradually accumulate on the surface of the coil to form a hard scale layer, which not only increases the heat transfer resistance and reduces the hydrolysis efficiency, but may also cause local overheating and further aggravate corrosion. The foaming phenomenon mainly occurs when the hydrolyzer is close to the design output. The reasons are multifaceted and may be related to factors such as surfactants in the solution and gas precipitation rate. Foaming will not only lead to false liquid levels and affect the judgment of operators, but may also hinder the flow and mixing of the solution and affect the uniformity of the hydrolysis reaction.

[0004] Due to the lack of monitoring means, the hydrolyzer currently only monitors the temperature and liquid level in real time, and lacks monitoring of chloride ions, iron ions, etc. in the urea solution, and there is no monitoring means for foaming. Power plants usually discharge part of the solution in the hydrolyzer as waste liquid, but due to the lack of monitoring means, for a running hydrolyzer, the waste liquid is discharged every few days, and the amount of waste liquid discharged each time is currently managed in a rough manner, and the discharge is based on experience. It may be that the discharge is too little, which will affect the operation of the hydrolyzer, or it may be that the discharge is too much, at this time a lot of urea solution is wasted. Summary of the invention

[0005] Aiming at the problems in the prior art that the composition and foaming of urea solution cannot be monitored, the sewage management is extensive, resulting in frequent operation problems of the hydrolyzer and waste of urea. The present invention provides a urea hydrolysis sewage discharge cycle and sewage discharge amount control system, which controls the urea hydrolysis sewage discharge cycle and sewage discharge amount through real-time sampling of the solution and real-time analysis of ions in the solution, discharges sewage from the hydrolyzer in a timely and appropriate manner, ensures the normal operation of the hydrolyzer, and avoids waste of urea solution.

[0006] In order to achieve the above object, the present invention provides the following technical solutions.

[0007] In the first aspect, the present invention provides a urea hydrolysis sewage discharge cycle and sewage discharge amount control system, including a sewage discharge unit, a surface sewage discharge unit and a bypass circulation unit; the sewage discharge unit includes a sewage discharge main valve and a sewage discharge secondary valve; the bypass circulation unit includes a bypass circulation primary valve, a bypass circulation secondary valve, a bypass sewage discharge valve and an online analysis device; one end of the sewage discharge main valve is connected to a urea hydrolysis reactor, the other end of the sewage discharge main valve is connected to one end of the sewage discharge secondary valve, and the other end of the sewage discharge secondary valve is connected to a wastewater tank; one end of the bypass circulation primary valve is connected to the sewage discharge secondary valve, and the other end of the sewage discharge secondary valve is connected to a wastewater tank; one end of the bypass circulation primary valve is connected to the sewage discharge secondary valve, and the other end of the bypass circulation primary valve is connected to the sewage discharge secondary valve. One end of the bypass sewage discharge valve is arranged between the main sewage discharge valve and the secondary sewage discharge valve, the other end of the bypass circulation primary valve is connected to one end of the bypass circulation secondary valve, and the other end of the bypass circulation secondary valve is connected to the urea hydrolysis reactor; the online analysis device is arranged between the bypass circulation primary valve and the bypass circulation secondary valve; one end of the bypass sewage discharge valve is connected between the bypass circulation secondary valve and the online analysis device, and the other end of the bypass sewage discharge valve is connected to the wastewater tank; one end of the surface sewage discharge unit is connected to the urea hydrolysis reactor, and the other end of the surface sewage discharge unit is connected to the wastewater tank.

[0008] As a further improvement of the present invention, a monitoring device is provided inside the urea hydrolysis reactor.

[0009] As a further improvement of the present invention, the monitoring device includes a camera.

[0010] As a further improvement of the present invention, the surface sewage discharge unit includes a surface sewage discharge valve; one end of the surface sewage discharge valve is connected to the urea hydrolysis reactor, and the other end of the surface sewage discharge unit is connected to the wastewater tank.

[0011] As a further improvement of the present invention, the surface sewage discharge valve is connected to the surface sewage discharge interface of the urea hydrolysis reactor.

[0012] As a further improvement of the present invention, the online analysis device includes a chloride ion online analysis device, a sodium ion online analysis device, an iron ion online analysis device and a carbonate ion online analysis device; the chloride ion online analysis device, the sodium ion online analysis device, the iron ion online analysis device and the carbonate ion online analysis device are arranged between the bypass circulation primary valve and the bypass circulation secondary valve.

[0013] As a further improvement of the present invention, one end of the main sewage valve is connected to the drainage and sewage interface of the urea hydrolysis reactor.

[0014] As a further improvement of the present invention, the other end of the bypass circulation secondary valve is connected to the liquid phase reflux interface of the urea hydrolysis reactor.

[0015] In a second aspect, the present invention provides a method for controlling a urea hydrolysis and sewage discharge cycle and sewage discharge volume control system, based on the urea hydrolysis and sewage discharge cycle and sewage discharge volume control system, comprising: The main sewage valve in the sewage discharge unit is opened, and the secondary sewage valve is closed; the surface sewage discharge unit is closed; The bypass circulation primary valve in the bypass circulation unit is opened, the bypass circulation secondary valve is opened, and the bypass drain valve is closed; at this time, the hydrolyzate in the urea hydrolysis reactor flows back to the urea hydrolysis reactor through the bypass circulation unit; When the hydrolyzate in the urea hydrolysis reactor flows through the online analysis device, the online analysis device will analyze and detect the ion concentration in the hydrolyzate. If the detection result is greater than the set value; Then immediately close the bypass circulation secondary valve, open the sewage secondary valve and the bypass sewage valve, and the hydrolyzate enters the wastewater pool through the sewage secondary valve and the bypass sewage valve.

[0016] As a further improvement of the present invention, it includes: when the existence time of bubbles on the internal liquid surface in the urea hydrolysis reactor exceeds a set time, the surface sewage discharge unit is opened to discharge sewage from the internal surface of the urea hydrolysis reactor.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses an integrated online analysis device, and the system can monitor the composition of the solution in the urea hydrolysis reactor in real time, including the concentration of key ions, so as to accurately determine when and how much sewage is needed. This precise control avoids the extensive operation in traditional sewage management and effectively reduces unnecessary urea waste. Secondly, the present invention can take timely measures, such as adjusting the sewage discharge strategy, when the urea solution composition or foaming situation is abnormal through real-time monitoring and early warning mechanisms, thereby effectively preventing the hydrolyzer from shutting down or reducing efficiency due to problems accumulated in long-term operation. This not only improves the stability and reliability of the equipment, but also reduces maintenance costs and downtime. Therefore, the present invention ensures that each sewage discharge is necessary and the amount is moderate through intelligent control of sewage discharge, avoiding waste of resources and environmental pollution caused by excessive sewage discharge. At the same time, precise control also ensures the quality of the solution in the urea hydrolysis reactor, which is conducive to maintaining an efficient hydrolysis reaction, thereby improving the overall resource utilization efficiency, reducing unnecessary sewage discharge and urea waste, and reducing the demand for wastewater treatment and the discharge of environmental pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are for explanation purposes only and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only for illustration purposes to help understand the present invention, and are not intended to specifically limit the shapes and proportional dimensions of the components of the present invention. In the drawings: Figure 1 The present invention is a schematic structural diagram of a urea hydrolysis sewage discharge cycle and sewage discharge volume control system.

[0019] In the figure: 101 is a urea hydrolysis reactor; 1 is a main sewage valve; 2 is a secondary sewage valve; 3 is a bypass circulation primary valve; 4 is a chloride ion online analysis device; 5 is a sodium ion online analysis device; 6 is an iron ion online analysis device; 7 is a carbonate ion online analysis device; 8 is a bypass circulation secondary valve; 9 is a bypass sewage valve; 10 is a surface sewage valve; 11 is a wastewater tank. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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 should fall within the scope of protection of the present invention.

[0021] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0023] like Figure 1 As shown, a urea hydrolysis sewage discharge cycle and sewage discharge amount control system of the present invention includes a sewage discharge unit, a surface sewage discharge unit and a bypass circulation unit.

[0024] The sewage discharge unit includes a sewage discharge main valve 1 and a sewage discharge secondary valve 2; The surface drainage unit includes a surface drainage valve 10; The bypass circulation unit comprises a bypass circulation primary valve 3, a bypass circulation secondary valve 8, a bypass drain valve 9 and an online analysis device.

[0025] One end of the main sewage valve 1 is connected to the drain and sewage interface of the urea hydrolysis reactor 101 through a pipeline, and the other end of the main sewage valve 1 is connected to one end of the sewage secondary valve 2 through a pipeline, and the other end of the sewage secondary valve 2 is connected to the wastewater tank 11 through a pipeline.

[0026] One end of the surface drain valve 10 is connected to the surface drain interface of the urea hydrolysis reactor 101 through a pipeline; the other end of the surface drain valve 10 is connected to the wastewater tank 11 through a pipeline.

[0027] One end of the bypass circulation secondary valve 8 is connected to the liquid phase reflux interface of the urea hydrolysis reactor 101 through a pipeline, and the other end of the bypass circulation secondary valve 8 is connected to one end of the bypass circulation primary valve 3 through a pipeline. An online analysis device is arranged in the pipeline between the bypass circulation secondary valve 8 and the bypass circulation primary valve 3, and the other end of the bypass circulation secondary valve 3 is connected to the pipeline between the sewage main valve 1 and the sewage secondary valve 2.

[0028] One end of the bypass drain valve 9 is connected between the bypass circulation secondary valve 8 and the online analysis device, and the other end of the bypass drain valve 9 is connected to the wastewater tank 11 through a pipeline.

[0029] The online analysis device includes a chloride ion online analysis device 4 , a sodium ion online analysis device 5 , an iron ion online analysis device 6 and a carbonate ion online analysis device 7 .

[0030] The chloride ion online analysis device 4 , the sodium ion online analysis device 5 , the iron ion online analysis device 6 and the carbonate ion online analysis device 7 are sequentially arranged between the bypass circulation primary valve 3 and the bypass circulation secondary valve 8 .

[0031] A monitoring device is provided inside the urea hydrolysis reactor 101 for monitoring the liquid level of the urea hydrolysis reactor 101. When bubbles are found to exist on the liquid level for a long time, the surface drain valve 10 is opened to discharge the surface waste.

[0032] The monitoring device includes but is not limited to a camera.

[0033] The second object of the present invention is to provide a control method of a corrosion factor monitoring system, comprising: A sewage pipe is led out from the drain and sewage interface of the urea hydrolysis reactor 101, and the total sewage discharge amount is controlled by the sewage main valve 1 in the sewage discharge unit.

[0034] After the sewage passes through the main sewage valve 1, a part of the hydrolyzed liquid is controlled by the secondary sewage valve 2 and directly flows into the wastewater tank 11, and the other part of the hydrolyzed liquid enters the bypass circulation unit and is controlled by the bypass circulation primary valve 3 to circulate back to the urea hydrolysis reactor 101.

[0035] During operation, the main sewage valve 1 is open all year round, the sewage secondary valve 2 is closed, the bypass circulation primary valve 3 is opened, and the bypass circulation secondary valve 8 is opened. At this time, the hydrolyzate is circulated back to the urea hydrolysis reactor 101 through the bypass, and the ion concentration in the solution is analyzed when flowing through the online analysis device. At this time, the data is transmitted back to the control system. When the real-time detection result is greater than the set value, the urea hydrolysis reactor 101 is at risk of corrosion. The control system immediately closes the bypass circulation secondary valve 8, opens the sewage secondary valve 2 and the bypass sewage valve 9. At this time, the hydrolyzate enters the sewage pipe through the sewage secondary valve 2 and is discharged into the wastewater tank 11, or enters the bypass pipe through the bypass sewage valve 9 and is discharged into the wastewater tank 11.

[0036] Since the bypass circulation secondary valve 8 is closed, the hydrolyzate will not circulate back to the urea hydrolysis reactor 101. At this time, this path allows the solution to continue to pass through the monitoring device to obtain the concentration of each ion in the hydrolyzate in real time.

[0037] The control method of the corrosion factor monitoring system of the present invention can realize the monitoring and prediction of the corrosion elements of the urea hydrolysis reactor 101.

[0038] The main sewage valve 1 is open all year round, the sewage secondary valve 2 is closed, the bypass circulation primary valve 3 is opened, and the bypass circulation secondary valve 8 is opened. At this time, the hydrolyzate is circulated back to the urea hydrolysis reactor 101 through the bypass, and the chloride ion concentration in the solution is analyzed by the chloride ion online analysis device 4 in the online analysis device when flowing through the online analysis device. At this time, the data is transmitted back to the control system. When the real-time detection result is greater than 100, at this mg / L, the urea hydrolysis reactor 101 has a corrosion risk, and the control system immediately closes the bypass circulation secondary valve 8, opens the sewage secondary valve 2 and the bypass sewage valve 9. At this time, the hydrolyzate enters the sewage pipe through the sewage secondary valve 2 and is discharged into the wastewater tank 11, or enters the bypass pipe through the bypass sewage valve 9 and is discharged into the wastewater tank 11.

[0039] Since the bypass circulation secondary valve 8 is closed, the hydrolyzate will not circulate back to the urea hydrolysis reactor 101. At this time, this path allows the solution to continue to pass through the monitoring device to obtain the chloride ion concentration of the hydrolyzate in real time.

[0040] The control method of the corrosion factor monitoring system of the present invention can realize the monitoring and prediction of scaling elements of the urea hydrolysis reactor 101.

[0041] For scaling, the present invention provides a sodium ion online analysis device 5, an iron ion online analysis device 6, and a carbonate ion online analysis device 7 on the basis of the bypass circulation unit and the chloride ion online analysis device 4.

[0042] A sewage pipe is led out from the drain and sewage interface of the urea hydrolysis reactor 101, and the total amount is controlled by the sewage main valve 1. There are two pipes behind the sewage main valve 1, one of which leads directly to the wastewater tank 11 and is controlled by the sewage secondary valve 2; the other circulates back to the urea hydrolysis reactor 101 and is controlled by the bypass circulation primary valve 3.

[0043] During operation, the main sewage valve 1 is always open, the secondary sewage valve 2 is closed, the bypass circulation primary valve 3 is opened, and the bypass circulation secondary valve 8 is opened. At this time, the hydrolyzate returns to the urea hydrolysis reactor 101 through the bypass circulation unit. After flowing through the sodium ion online analysis device 5, the iron ion online analysis device 6, and the carbonate ion online analysis device 7, the concentrations of sodium ions, iron ions, and carbonate ions in the solution are analyzed. At this time, the data is transmitted back to the control system, and the solubility product of iron carbonate and sodium chloride is calculated. The calculated result is compared with the critical value. When the solubility product exceeds the critical value ( ), indicating that the urea hydrolysis reactor 101 has a scaling risk at this time, the control system closes the bypass circulation secondary valve 8, opens the sewage secondary valve 2 and the bypass sewage valve 9, so that the solution is discharged into the wastewater tank 11. At this time, since the bypass circulation secondary valve 8 is closed, the solution will not circulate back to the urea hydrolysis reactor 101, and at the same time, the solution can continue to pass through the online analysis device to obtain the concentrations of sodium ions, iron ions, and carbonate ions in real time.

[0044] When the concentrations of sodium ions, iron ions, and carbonate ions are lower than the critical value ( ), indicating that the scaling risk of the urea hydrolysis reactor 101 is eliminated. At this time, the secondary sewage valve 2 and the bypass sewage valve 9 are closed, and the bypass circulation secondary valve 8 is opened.

[0045] Solubility product means that although the sparingly soluble electrolyte is sparingly soluble, some anions and cations still enter the solution, and at the same time, the anions and cations that enter the solution will be deposited on the solid surface. When the rates of these two processes are equal, the dissolution of the sparingly soluble electrolyte reaches a state of equilibrium, and the amount of solid no longer decreases. The specific calculation process of the solubility product is as follows:

[0046] It is a constant under certain temperature and pressure conditions. When Scaling will occur at this time.

[0047] The corrosion factor monitoring system of the present invention can realize the monitoring and intelligent identification of the foaming phenomenon of the urea hydrolysis reactor 101.

[0048] During the production and transportation of urea and the preparation and transportation of urea solution, other impurities may be mixed in, such as alcohols, aldehydes, organic acids, phosphates, etc. Some impurities have high surface activity and foaming properties. These impurities are brought into the urea hydrolysis reactor and continue to accumulate with the operation time, which will change the physical properties of the solution such as viscosity and surface tension, and will not only increase the possibility of foaming of urea solution, but also enhance the stability of foam, so that the foam will not be eliminated for a long time. If the foam generated in the urea hydrolysis reactor cannot be handled in time, it will harm the normal operation of the urea hydrolysis system and flue gas denitrification.

[0049] The present invention sets a monitoring camera in the urea hydrolysis reactor 101, and the camera is aimed at the liquid surface of the urea hydrolysis reactor 101, and the liquid surface is recorded in real time, and the picture is transmitted back to the control system. The picture is identified by the analysis software. When it is found that there are bubbles on the liquid surface for a long time, the analysis software gives a signal to the control system, and the control system controls the surface drain valve 10 to open and discharge the surface sewage.

[0050] According to the different angles described above, a method for obtaining the urea discharge start signal is given. After the discharge starts, the discharge duration is also a very important parameter. On the basis of the above, the present invention sets the normal ion concentration in the solution, the solubility product critical value and the signal of the disappearance of the foaming phenomenon as a signal to stop the discharge.

[0051] For chloride ions, when the real-time detection result of sewage discharge is less than 100 mg / L, it indicates that there is no corrosion risk in the urea hydrolysis reactor 101. The control system closes the sewage secondary valve 2, opens the bypass circulation primary valve 3 and the bypass circulation secondary valve 8, and closes the bypass sewage valve 9. At this time, the solution returns to the urea hydrolysis reactor 101 through the circulation pipeline to achieve monitoring and recycling; for sodium ions, iron ions, and carbonate ions, when , indicating that the scaling risk of the urea hydrolysis reactor 101 is eliminated at this time, and the control system closes the secondary sewage valve 2, opens the bypass circulation primary valve 3 and the bypass circulation secondary valve 8, and closes the bypass sewage valve 9; for the foaming phenomenon, when the analysis software recognizes the picture and finds that there are no bubbles on the liquid surface, the analysis software gives a signal to the control system, and the control system controls the surface sewage valve 10 to close and stop surface sewage discharge.

[0052] The present invention aims at three common problems of the urea hydrolysis reactor 101, and analyzes the typical representative factors thereof. For corrosion, the present invention sets a hydrolyzed liquid bypass sampling device and a chloride ion online analysis device to realize real-time sampling of the hydrolyzed liquid and real-time analysis of the chloride ions, and sends a sewage discharge signal when the chloride ions exceed a certain limit value; for scaling, the present invention sets sodium ion, iron ion, and carbonate ion online analysis devices on the basis of the hydrolyzed liquid bypass sampling device and the chloride ion online analysis device, and calculates the solubility product of iron carbonate in real time, evaluates the possibility of scaling, and sends out an early warning and sewage discharge signal; for foaming, the present invention sets a monitoring device in the urea hydrolysis reactor 101, monitors the picture of the liquid surface of the urea hydrolysis reactor 101 in real time, and judges whether there is foaming. Once foaming occurs, the surface sewage discharge is started.

[0053] In summary, the present invention controls the urea hydrolysis discharge cycle and discharge amount through real-time sampling of the solution and real-time analysis of ions in the solution, combined with the upper and lower limits of the indicators set by the present invention, and discharges the urea hydrolysis reactor 101 in a timely and appropriate manner to avoid corrosion, scaling and foaming of the urea hydrolysis reactor 101, thereby achieving real-time monitoring and early warning, and avoiding waste of urea solution.

[0054] Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a disclaimer of such subject matter, nor should it be considered that the applicants did not consider such subject matter to be part of the disclosed inventive subject matter.

[0055] The above content is a further detailed description of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, they can also make several simple deductions or substitutions, which should be regarded as belonging to the protection scope of the present invention determined by the submitted claims.

Claims

1. A urea hydrolysis sewage discharge cycle and sewage discharge control system, characterized in that: It includes a sewage discharge unit, a surface sewage discharge unit and a bypass circulation unit; The sewage discharge unit comprises a sewage discharge main valve (1) and a sewage discharge secondary valve (2); The bypass circulation unit comprises a bypass circulation primary valve (3), a bypass circulation secondary valve (8), a bypass sewage valve (9) and an online analysis device; One end of the sewage main valve (1) is connected to the urea hydrolysis reactor (101), the other end of the sewage main valve (1) is connected to one end of the sewage secondary valve (2), and the other end of the sewage secondary valve (2) is connected to the wastewater tank (11); One end of the bypass circulation primary valve (3) is arranged between the sewage discharge main valve (1) and the sewage discharge secondary valve (2), the other end of the bypass circulation primary valve (3) is connected to one end of the bypass circulation secondary valve (8), and the other end of the bypass circulation secondary valve (8) is connected to the urea hydrolysis reactor (101); The online analysis device is arranged between the bypass circulation primary valve (3) and the bypass circulation secondary valve (8); One end of the bypass drain valve (9) is connected between the bypass circulation secondary valve (8) and the online analysis device, and the other end of the bypass drain valve (9) is connected to the wastewater tank (11); One end of the surface sewage discharge unit is connected to the urea hydrolysis reactor (101), and the other end of the surface sewage discharge unit is connected to the wastewater tank (11).

2. A urea hydrolysis and sewage discharge cycle and sewage discharge control system according to claim 1, characterized in that: A monitoring device is provided inside the urea hydrolysis reactor (101).

3. A urea hydrolysis and sewage discharge cycle and sewage discharge control system according to claim 2, characterized in that: The monitoring device includes a camera.

4. A urea hydrolysis and discharge cycle and discharge volume control system according to claim 1, characterized in that: The surface drainage unit comprises a surface drainage valve (10); One end of the surface sewage discharge valve (10) is connected to the urea hydrolysis reactor (101), and the other end of the surface sewage discharge unit is connected to the wastewater tank (11).

5. A urea hydrolysis and sewage discharge cycle and sewage discharge control system according to claim 4, characterized in that: The surface sewage discharge valve (10) is connected to the surface sewage discharge interface of the urea hydrolysis reactor (101).

6. A urea hydrolysis and discharge cycle and discharge volume control system according to claim 1, characterized in that: The online analysis device comprises a chloride ion online analysis device (4), a sodium ion online analysis device (5), an iron ion online analysis device (6) and a carbonate ion online analysis device (7); The chloride ion online analysis device (4), the sodium ion online analysis device (5), the iron ion online analysis device (6) and the carbonate ion online analysis device (7) are arranged between the bypass circulation primary valve (3) and the bypass circulation secondary valve (8).

7. A urea hydrolysis and discharge cycle and discharge volume control system according to claim 1, characterized in that: One end of the main sewage valve (1) is connected to the drainage and sewage interface of the urea hydrolysis reactor (101).

8. A urea hydrolysis and sewage discharge cycle and sewage discharge control system according to claim 1, characterized in that: The other end of the bypass circulation secondary valve (8) is connected to the liquid phase reflux interface of the urea hydrolysis reactor (101).

9. A method for controlling a urea hydrolysis wastewater discharge cycle and a wastewater discharge control system, characterized in that: A urea hydrolysis and sewage discharge cycle and sewage discharge control system according to any one of claims 1 to 8, comprising: The main sewage discharge valve (1) in the sewage discharge unit is opened, and the secondary sewage discharge valve (2) is closed; the surface sewage discharge unit is closed; The bypass circulation primary valve (3) in the bypass circulation unit is opened, the bypass circulation secondary valve (8) is opened, and the bypass sewage valve (9) is closed; at this time, the hydrolyzate in the urea hydrolysis reactor (101) flows back to the urea hydrolysis reactor (101) through the bypass circulation unit; When the hydrolyzate in the urea hydrolysis reactor (101) flows through the online analysis device, the online analysis device will analyze and detect the ion concentration in the hydrolyzate. If the detection result is greater than the set value; The bypass circulation secondary valve (8) is immediately closed, and the sewage secondary valve (2) and the bypass sewage valve (9) are opened. At this time, the hydrolyzate enters the wastewater tank (11) through the sewage secondary valve (2) and the bypass sewage valve (9).

10. The control method of a urea hydrolysis and discharge cycle and discharge volume control system according to claim 9, characterized in that: include: When the bubbles on the internal liquid surface of the urea hydrolysis reactor (101) exist for a time exceeding a set time, the surface sewage discharge unit is turned on to discharge sewage from the internal surface of the urea hydrolysis reactor (101).

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