Waste water graded discharge control system and method

Abstract

The invention provides a waste water graded discharge control system and method, a lower-section waste water container of the system is connected with a first-section waste water discharge port of a COAP system through a first-section waste water discharge switch unit, the lower-section waste water container is connected with an alkali adding device, and the lower-section waste water container is connected with a lower-section waste water discharge unit; the middle-upper-section wastewater container is connected with a second-section wastewater first discharge port through a second-section wastewater discharge switch unit, the middle-upper-section wastewater container is connected with a middle-upper-section wastewater discharge unit, and a second second-section wastewater discharge port is connected with a first-section wastewater replenishing inlet through a first-section water replenishing switch unit; the control unit is used for opening the first-section wastewater discharge switch unit when the first-section wastewater liquid level is higher than the corresponding upper limit; when the lower-section wastewater liquid level is higher than the corresponding upper limit and the first PH value meets the requirement, the lower-section wastewater discharge unit is controlled to discharge water; a first-section water supplementing switch unit is controlled to be switched on in a timed mode so as to supplement water to first-section waste water; when the middle-upper section wastewater liquid level is higher than the corresponding upper limit and the second PH value meets the requirement, the middle-upper section wastewater discharge unit is controlled to discharge water.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a wastewater graded discharge control system and method. Background Art

[0002] When applying the "low-temperature integrated pollutant removal technology" (abbreviated as: COAP), the first step is to cool the flue gas to a sub-zero temperature zone. The cooling process uses a four-stage spray cooling method to gradually reduce the flue gas temperature. Different types of wastewater will be generated at different stages during the flue gas cooling process. Different treatments for different types of wastewater can better optimize resource allocation. However, there is currently a lack of treatment technology for different types of wastewater generated during the deep cooling process of flue gas. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0004] To this end, the first object of the present invention is to propose a wastewater hierarchical discharge control system to better optimize resource allocation.

[0005] The second object of the present invention is to provide a wastewater graded discharge control method.

[0006] To achieve the above-mentioned purpose, the first aspect of the present invention proposes a wastewater hierarchical discharge control system, comprising a first-stage wastewater discharge switch unit, a lower-stage wastewater container, a lower-stage wastewater discharge unit, a first-stage water replenishment switch unit, a second-stage wastewater discharge switch unit, a middle-upper-stage wastewater container, a middle-upper-stage wastewater discharge unit and a control unit; the first inlet of the lower-stage wastewater container is connected to the first-stage wastewater discharge outlet of the COAP system through the first-stage wastewater discharge switch unit, the second inlet of the lower-stage wastewater container is connected to an alkali adding device, and the outlet of the lower-stage wastewater container is connected to the lower-stage wastewater discharge unit; the inlet of the middle-upper-stage wastewater container is connected to the second-stage wastewater first discharge outlet of the COAP system through the second-stage wastewater discharge switch unit, the outlet of the middle-upper-stage wastewater container is connected to the middle-upper-stage wastewater discharge unit, and the second-stage wastewater second discharge outlet of the COAP system is connected to the first-stage wastewater replenishment inlet of the COAP system through the first-stage water replenishment switch unit;

[0007] For the lower wastewater, the control unit is used to open the wastewater discharge switch unit of the first section when the wastewater level of the first section is higher than the upper limit of the wastewater level of the first section; when the wastewater level of the lower section is higher than the upper limit of the wastewater level of the lower section and the first pH value meets the requirement, control the wastewater discharge unit of the lower section to drain water;

[0008] For the middle and upper sections of wastewater, the control unit is used to time the conduction of the first section water replenishment switch unit to replenish water into a section of wastewater; when the liquid level of the middle and upper sections of wastewater is higher than the upper limit of the liquid level of the middle and upper sections of wastewater and the second pH value meets the requirements, the middle and upper sections of wastewater discharge unit is controlled to drain water.

[0009] In the wastewater staged discharge control system provided in the first aspect of the present invention, for the lower wastewater, the control unit is further used to close the wastewater discharge switch unit of one section when the liquid level of one section of wastewater is lower than the lower limit of the liquid level of one section of wastewater.

[0010] In the wastewater staged discharge control system provided in the first aspect of the present invention, for the lower wastewater, the control unit is also used to control the closure of the lower wastewater discharge unit when the liquid level of the lower wastewater is lower than the lower limit of the liquid level of the lower wastewater.

[0011] In the wastewater staged discharge control system provided in the first aspect of the present invention, for the lower section wastewater, the control unit is also used to control the start of the alkali adding device when the first pH value is less than the set pH value lower limit, and control the stop of the alkali adding device when the first pH value is greater than the set pH value upper limit.

[0012] In the wastewater staged discharge control system provided in the first aspect of the present invention, the first-stage wastewater discharge switch unit adopts a first-stage wastewater discharge valve.

[0013] In the wastewater staged discharge control system provided in the first aspect of the present invention, the lower-stage wastewater discharge unit adopts a lower-stage wastewater pump.

[0014] In the wastewater staged discharge control system provided in the first aspect of the present invention, the third inlet of the lower wastewater container is connected to the four-stage wastewater discharge outlet of the COAP system via the MVR system.

[0015] In the wastewater staged discharge control system provided in the first aspect of the present invention, the fourth inlet of the lower wastewater container is connected to the salt making system of the COAP system.

[0016] The wastewater graded discharge control system provided in the first aspect of the present invention also includes three sections of overflow pipes, which are used to connect the three-section wastewater discharge outlet of the COAP system and the second-section spraying equipment of the COAP system.

[0017] To achieve the above-mentioned purpose, the second aspect of the present invention proposes a wastewater graded discharge control method, which is applied to the wastewater graded discharge control system provided in the first aspect of the present invention, and the method comprises:

[0018] When the level of a wastewater in a section is higher than the upper limit of the level of a wastewater in a section, the switch unit for discharging a wastewater in a section is opened; when the level of a wastewater in a section is lower than the lower limit of the level of a wastewater in a section, the switch unit for discharging a wastewater in a section is closed;

[0019] When the liquid level of the lower wastewater is higher than the upper limit of the liquid level of the lower wastewater and the first pH value meets the requirement, the lower wastewater discharge unit is controlled to discharge water;

[0020] When the first pH value is less than a set pH lower limit, the alkali adding device is controlled to start, and when the first pH value is greater than a set pH upper limit, the alkali adding device is controlled to stop;

[0021] Timingly controlling a section of water replenishment switch unit to be turned on to replenish water to a section of wastewater;

[0022] When the liquid level of the wastewater in the middle and upper section is higher than the upper liquid level limit of the wastewater in the middle and upper section and the second pH value meets the requirement, the wastewater discharge unit in the middle and upper section is controlled to drain water.

[0023] The present invention provides a wastewater hierarchical discharge control system and method, the control system comprises a first-stage wastewater discharge switch unit, a lower-stage wastewater container, a lower-stage wastewater discharge unit, a first-stage water replenishment switch unit, a second-stage wastewater discharge switch unit, a middle-upper-stage wastewater container, a middle-upper-stage wastewater discharge unit and a control unit; the first inlet of the lower-stage wastewater container is connected to a first-stage wastewater discharge outlet of a COAP system via the first-stage wastewater discharge switch unit, the second inlet of the lower-stage wastewater container is connected to an alkali adding device, and the outlet of the lower-stage wastewater container is connected to the lower-stage wastewater discharge unit; the inlet of the middle-upper-stage wastewater container is connected to a second-stage wastewater first discharge outlet of the COAP system via the second-stage wastewater discharge switch unit, and the outlet of the middle-upper-stage wastewater container is connected to the lower-stage wastewater discharge unit. The control unit is connected to the middle-upper wastewater discharge unit, and the second discharge outlet of the second-stage wastewater of the COAP system is connected to the first-stage wastewater replenishment inlet of the COAP system through the first-stage water replenishment switch unit; for the lower-stage wastewater, the control unit is used to open the first-stage wastewater discharge switch unit when the first-stage wastewater level is higher than the first-stage wastewater level upper limit; when the lower-stage wastewater level is higher than the lower-stage wastewater level upper limit and the first PH value meets the requirement, the lower-stage wastewater discharge unit is controlled to drain water; for the middle-upper wastewater, the control unit is used to timedly control the first-stage water replenishment switch unit to conduct so as to replenish water into the first stage of wastewater; when the middle-upper wastewater level is higher than the middle-upper wastewater level upper limit and the second PH value meets the requirement, the middle-upper wastewater discharge unit is controlled to drain water. In this case, considering that a large amount of condensed water will be generated during the second and third stage spraying of the flue gas in the cooling process, the lower wastewater corresponding to the first stage spraying and the middle and upper wastewater corresponding to the second and third stage spraying are respectively subjected to emission control treatment, and the condensed water generated by the second stage spraying is recycled and reused to regularly replenish the first stage wastewater to control the pollutant concentration of the first stage wastewater, thereby reducing the wastewater treatment cost, realizing the recycling of water resources of the condensed water, and optimizing resource allocation.

[0024] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0026] Figure 1 A block diagram of a wastewater graded discharge control system provided by an embodiment of the present invention;

[0027] Figure 2 This is a flow chart of a wastewater graded discharge control method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the embodiments of the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the embodiments of the present invention as detailed in the appended claims.

[0029] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0030] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. It should also be understood that the term "and / or" used in the present invention refers to and includes any or all possible combinations of one or more associated listed items.

[0031] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0032] Considering that the COAP technology flue gas cooling system adopts a four-stage spray cycle cooling method, the first, second and third stage sprays use industrial water, the fourth stage spray uses calcium chloride solution, and the salt making system also has wastewater discharge. The condensed water precipitated from different cooling sections of the spray tower has different water quality, so the drainage water quality is different. Therefore, if the wastewater generated by the flue gas condensation process can be graded, it will be possible to optimize resource allocation and utilization.

[0033] Based on this, the present invention proposes a wastewater graded discharge control system and method to better optimize resource allocation. The wastewater graded discharge control system in the present invention can be referred to as a system.

[0034] In this embodiment, the wastewater hierarchical discharge control system includes a first-stage wastewater discharge switch unit, a lower-stage wastewater container, a lower-stage wastewater discharge unit and a control unit. The first inlet of the lower-stage wastewater container is connected to a first-stage wastewater discharge outlet of the COAP system through the first-stage wastewater discharge switch unit, the second inlet of the lower-stage wastewater container is connected to the alkali adding device, and the outlet of the lower-stage wastewater container is connected to the lower-stage wastewater discharge unit.

[0035] In this embodiment, the first-stage wastewater discharge switch unit may adopt a first-stage wastewater discharge valve.

[0036] In this embodiment, the lower wastewater discharge unit may adopt a lower wastewater pump.

[0037] In this embodiment, the third inlet of the lower wastewater container is connected to the four-stage wastewater outlet of the COAP system through the MVR (mechanical vapor recompression, evaporation crystallization technology) system. A four-stage spray pump is arranged between the MVR system and the four-stage wastewater outlet of the COAP system.

[0038] In this embodiment, the fourth inlet of the lower wastewater container is connected to the salt production system of the COAP system.

[0039] In this embodiment, the wastewater hierarchical discharge control system further includes a first-stage water replenishment switch unit, a second-stage wastewater discharge switch unit, a middle-upper stage wastewater container, and a middle-upper stage wastewater discharge unit. The inlet of the middle-upper stage wastewater container is connected to the first discharge outlet of the second-stage wastewater of the COAP system via the second-stage wastewater discharge switch unit. The outlet of the middle-upper stage wastewater container is connected to the middle-upper stage wastewater discharge unit, and the second discharge outlet of the second-stage wastewater of the COAP system is connected to the first-stage wastewater replenishment inlet of the COAP system via the first-stage water replenishment switch unit.

[0040] In this embodiment, the first-stage water replenishment switch unit can adopt a two-stage spray pump.

[0041] In this embodiment, the upper-middle section wastewater discharge unit may adopt an upper-middle section condensate pump.

[0042] In this embodiment, the system further includes a three-stage overflow pipe. The three-stage overflow pipe is used to connect the three-stage wastewater discharge outlet of the COAP system and the second-stage spraying equipment of the COAP system. Specifically, one end of the three-stage overflow pipe is connected to the second-stage spraying equipment of the COAP system, and the other end of the three-stage overflow pipe extends to the three-stage wastewater holding chamber through the three-stage wastewater discharge outlet of the COAP system. The three-stage wastewater in the three-stage wastewater holding chamber enters the three-stage overflow pipe through the three-stage overflow port on the three-stage overflow pipe and then reaches the second-stage spraying equipment for second-stage spraying.

[0043] In this embodiment, for the lower wastewater, the control unit is used to open a wastewater discharge switch unit when the wastewater level is higher than the upper limit of the wastewater level (e.g., 1.4 meters); it is also used to close a wastewater discharge switch unit when the wastewater level is lower than the lower limit of the wastewater level (e.g., 1 meter); it is also used to control the lower wastewater discharge unit to drain water when the wastewater level is higher than the upper limit of the wastewater level (e.g., 3.5 meters) and the first pH value meets the requirements (e.g., the first pH value is greater than 7); it is also used to control the closure of the lower wastewater discharge unit when the wastewater level is lower than the lower limit of the wastewater level (e.g., 1 meter). The control unit is also used to control the start of the alkali adding device when the first pH value is less than the set pH value lower limit (e.g., 6), and control the stop of the alkali adding device when the first pH value is greater than the set pH value upper limit (e.g., 8).

[0044] For the middle and upper wastewater, the control unit is used to control the first water replenishment switch unit to be turned on at a fixed time to replenish water into the first wastewater; it is also used to control the second wastewater discharge switch unit to be continuously turned on so that the second wastewater continues to flow to the middle and upper wastewater container. It is also used to control the middle and upper wastewater discharge unit to drain water when the middle and upper wastewater level is higher than the upper wastewater level upper limit and the second pH value meets the requirements. It is also used to control the closure of the middle and upper wastewater discharge unit when the middle and upper wastewater level is lower than the lower wastewater level lower limit.

[0045] If the concentrated wastewater of the MVR system and the wastewater generated by the salt making system also participate in the wastewater classification discharge control, take the first stage wastewater discharge switch unit using the first stage wastewater discharge valve, the lower stage wastewater discharge unit using the lower stage wastewater pump, the first stage water replenishment switch unit using the second stage spray pump, the second stage wastewater discharge switch unit using the second stage wastewater discharge valve, and the middle-upper stage wastewater discharge unit using the middle-upper stage condensate pump as an example. Figure 1 A block diagram of a wastewater staged discharge control system provided in an embodiment of the present invention.

[0046] Specifically, combined Figure 1 , the specific emission control process of the wastewater hierarchical emission control system is as follows:

[0047] Regarding the wastewater from the lower section, considering that the wastewater from the lower section collects the wastewater generated by the first spraying, the concentrated wastewater discharged by the MVR system, and the wastewater generated by the salt making system, these three parts of wastewater contain a large amount of SO 4 2- 、SO 3 2- and NO 3 - , which is highly acidic, is first neutralized by adding alkali in the wastewater classification discharge control treatment and then sent to the wastewater treatment system for disposal. The specific control methods are as follows:

[0048] 11) Monitor the level of the wastewater in one section, open the wastewater discharge valve in one section when the level is higher than 1.4 meters, and discharge the wastewater to the wastewater pool in the lower section (i.e., the wastewater container in the lower section), and close the wastewater discharge valve in one section when the level drops to 1 meter;

[0049] 12) Control the pipeline between the third inlet of the lower wastewater container and the MVR system to be in a conducting state, so that the wastewater discharge of the MVR system is continuous;

[0050] 13) Control the pipeline between the fourth inlet of the lower wastewater container and the salt-making system of the COAP system to be in a conducting state, so that the wastewater discharge of the salt-making system is continuous;

[0051] 14) Monitor the liquid level of the lower wastewater in the lower wastewater pool. If the liquid level of the lower wastewater is greater than 3.5 meters and the pH value of the lower wastewater is greater than 7, start the lower wastewater pump to send the lower wastewater to the wastewater treatment system to achieve drainage; if the liquid level of the lower wastewater is lower than 1 meter, control and stop the lower wastewater pump;

[0052] 15) Monitor the pH value of the lower wastewater in the lower wastewater pool. If the pH value is less than 6, the alkali adding device is started. If the pH value is greater than 8, the alkali adding device is stopped.

[0053] For the wastewater in the middle and upper sections, considering that the wastewater generated by the second and third stage spraying is mainly condensed water, the condensed water from the second and third stage spraying is collected and recycled according to the actual situation or sent to the water treatment system, circulating water replenishment and other disposal. The specific control methods are as follows:

[0054] 21) Timing control of the operation of the second-stage spray pump so that the condensed water (i.e., second-stage wastewater) generated in the second stage can be regularly replenished to the first stage, thereby achieving control of the concentration of pollutants in the first stage spray, and then discharged with the wastewater at the lower end;

[0055] 22) The condensed water (i.e., waste water from the third stage) produced in the third stage continuously flows to the second stage spraying through the third stage overflow pipe;

[0056] 23) Control the second-stage wastewater discharge valve to be continuously open so that the condensed water generated in the second stage can continuously flow to the middle-upper condensed water pool (i.e., the middle-upper wastewater container) through the corresponding overflow pipe;

[0057] 24) Considering that the water quality of the middle and upper condensed water is good, the water volume is large, and it is acidic, it can be used as circulating water replenishment to neutralize the pH of the circulating water, or it can be directly sent to the water treatment system for disposal. Therefore, the liquid level of the middle and upper condensed water in the middle and upper condensed water pool is monitored. If the liquid level of the middle and upper condensed water is greater than the corresponding liquid level upper limit and the pH is greater than the corresponding set value, the middle and upper condensed water pump is started to send the middle and upper condensed water to the water treatment system or circulating water replenishment, etc., to achieve drainage; if the liquid level of the middle and upper condensed water is lower than the corresponding lower limit, the middle and upper condensed water pump is controlled to stop.

[0058] The following is an embodiment of the method of the present invention. For details not disclosed in the embodiment of the method of the present invention, please refer to the embodiment of the system of the present invention. The embodiment of the method of the present invention proposes a wastewater graded discharge control method. The wastewater graded discharge control method is applied to the wastewater graded discharge control system of the above system embodiment to perform graded discharge control of wastewater.

[0059] Figure 2 This is a flow chart of a wastewater graded discharge control method provided in an embodiment of the present invention.

[0060] like Figure 2 As shown, the wastewater graded discharge control method comprises:

[0061] Step S101, when the level of a wastewater section is higher than the upper limit of the level of a wastewater section, the switch unit for discharging a wastewater section is opened; when the level of a wastewater section is lower than the lower limit of the level of a wastewater section, the switch unit for discharging a wastewater section is closed;

[0062] Step S102, when the lower wastewater level is higher than the lower wastewater level upper limit and the first pH value meets the requirement, the lower wastewater discharge unit is controlled to drain water;

[0063] Step S103, when the first pH value is less than the set pH lower limit, the alkali adding device is controlled to start, and when the first pH value is greater than the set pH upper limit, the alkali adding device is controlled to stop;

[0064] Step S104, timing control of a water replenishment switch unit to be turned on to replenish water to a section of wastewater;

[0065] Step S105, when the liquid level of the middle-upper section wastewater is higher than the upper liquid level limit of the middle-upper section wastewater and the second pH value meets the requirement, the middle-upper section wastewater discharge unit is controlled to drain water.

[0066] It should be noted that the aforementioned explanation of the embodiment of the wastewater staged discharge control system is also applicable to the wastewater staged discharge control method of this embodiment, which will not be repeated here.

[0067] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0068] In the wastewater staged discharge control system and method of the embodiment of the present invention, the control system includes a first-stage wastewater discharge switch unit, a lower-stage wastewater container, a lower-stage wastewater discharge unit, a first-stage water replenishment switch unit, a second-stage wastewater discharge switch unit, a middle-upper-stage wastewater container, a middle-upper-stage wastewater discharge unit and a control unit; the first inlet of the lower-stage wastewater container is connected to the first-stage wastewater discharge outlet of the COAP system through the first-stage wastewater discharge switch unit, the second inlet of the lower-stage wastewater container is connected to the alkali adding device, and the outlet of the lower-stage wastewater container is connected to the lower-stage wastewater discharge unit; the inlet of the middle-upper-stage wastewater container is connected to the second-stage wastewater first discharge outlet of the COAP system through the second-stage wastewater discharge switch unit, and the outlet of the middle-upper-stage wastewater container is connected to the lower-stage wastewater discharge unit. The outlet is connected to the middle-upper section wastewater discharge unit, and the second discharge outlet of the second section wastewater of the COAP system is connected to the first section wastewater replenishment inlet of the COAP system through the first section water replenishment switch unit; for the lower section wastewater, the control unit is used to open the first section wastewater discharge switch unit when the first section wastewater level is higher than the first section wastewater level upper limit; when the lower section wastewater level is higher than the lower section wastewater level upper limit and the first PH value meets the requirement, the lower section wastewater discharge unit is controlled to drain water; for the middle-upper section wastewater, the control unit is used to timedly control the first section water replenishment switch unit to be turned on to replenish water into the first section wastewater; when the middle-upper section wastewater level is higher than the middle-upper section wastewater level upper limit and the second PH value meets the requirement, the middle-upper section wastewater discharge unit is controlled to drain water. In this case, considering that a large amount of condensed water will be generated during the second and third stage spraying of the flue gas in the cooling process, the lower wastewater corresponding to the first stage spraying and the middle and upper wastewater corresponding to the second and third stage spraying are respectively subjected to emission control treatment, and the condensed water generated by the second stage spraying is recycled and regularly added to the first stage wastewater to control the pollutant concentration of the first stage wastewater. In this way, the wastewater of the COAP system is discharged in grades, which reduces the wastewater treatment cost, realizes the recycling of water resources of condensed water, and optimizes resource allocation.

[0069] The accompanying drawings show schematic diagrams of structures according to embodiments disclosed in the present invention. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0070] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and the present invention is not limited here.

[0071] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A wastewater graded discharge control system, characterized in that: It includes a first-stage wastewater discharge switch unit, a lower-stage wastewater container, a lower-stage wastewater discharge unit, a first-stage water replenishment switch unit, a second-stage wastewater discharge switch unit, a middle-upper-stage wastewater container, a middle-upper-stage wastewater discharge unit and a control unit; the first inlet of the lower-stage wastewater container is connected to the first-stage wastewater discharge outlet of the COAP system through the first-stage wastewater discharge switch unit, the second inlet of the lower-stage wastewater container is connected to the alkali adding device, and the outlet of the lower-stage wastewater container is connected to the lower-stage wastewater discharge unit; The inlet of the middle-upper wastewater container is connected to the first discharge outlet of the second-stage wastewater of the COAP system via the second-stage wastewater discharge switch unit, the outlet of the middle-upper wastewater container is connected to the middle-upper wastewater discharge unit, and the second discharge outlet of the second-stage wastewater of the COAP system is connected to the first-stage wastewater replenishment inlet of the COAP system via the first-stage replenishment switch unit; For the lower wastewater, the control unit is used to open the wastewater discharge switch unit of the first section when the wastewater level of the first section is higher than the upper limit of the wastewater level of the first section; when the wastewater level of the lower section is higher than the upper limit of the wastewater level of the lower section and the first pH value meets the requirement, control the wastewater discharge unit of the lower section to drain water; For the middle and upper sections of wastewater, the control unit is used to time the conduction of the first section water replenishment switch unit to replenish water into a section of wastewater; when the liquid level of the middle and upper sections of wastewater is higher than the upper limit of the liquid level of the middle and upper sections of wastewater and the second pH value meets the requirements, the middle and upper sections of wastewater discharge unit is controlled to drain water.

2. The wastewater graded discharge control system according to claim 1 is characterized in that: For the lower section of wastewater, the control unit is further used to close the wastewater discharge switch unit when the liquid level of the first section of wastewater is lower than the lower limit of the liquid level of the first section of wastewater.

3. The wastewater graded discharge control system according to claim 1 is characterized in that: For the lower wastewater, the control unit is also used to control the closing of the lower wastewater discharge unit when the liquid level of the lower wastewater is lower than the lower limit of the liquid level of the lower wastewater.

4. The wastewater graded discharge control system according to claim 1 is characterized in that: For the lower section wastewater, the control unit is also used to control the start of the alkali adding device when the first pH value is less than the set pH lower limit, and control the stop of the alkali adding device when the first pH value is greater than the set pH upper limit.

5. The wastewater graded discharge control system according to claim 1 is characterized in that: The one-stage wastewater discharge switch unit adopts a one-stage wastewater discharge valve.

6. The wastewater graded discharge control system according to claim 1 is characterized in that: The lower wastewater discharge unit adopts a lower wastewater pump.

7. The wastewater graded discharge control system according to claim 1 is characterized in that: The third inlet of the lower wastewater container is connected to the fourth wastewater outlet of the COAP system via the MVR system.

8. The wastewater graded discharge control system according to claim 1 is characterized in that: The fourth inlet of the lower wastewater container is connected to the salt production system of the COAP system.

9. The wastewater graded discharge control system according to claim 1, characterized in that: It also includes three sections of overflow pipes, which are used to connect the three sections of wastewater discharge outlets of the COAP system and the second section of spraying equipment of the COAP system.

10. A method for controlling wastewater discharge in stages, characterized in that: Applied to the wastewater graded discharge control system according to any one of claims 1 to 9, the method comprising: When the level of a wastewater in a section is higher than the upper limit of the level of a wastewater in a section, the switch unit for discharging a wastewater in a section is opened; when the level of a wastewater in a section is lower than the lower limit of the level of a wastewater in a section, the switch unit for discharging a wastewater in a section is closed; When the liquid level of the lower wastewater is higher than the upper limit of the liquid level of the lower wastewater and the first pH value meets the requirement, the lower wastewater discharge unit is controlled to discharge water; When the first pH value is less than a set pH lower limit, the alkali adding device is controlled to start, and when the first pH value is greater than a set pH upper limit, the alkali adding device is controlled to stop; Timingly controlling a section of water replenishment switch unit to be turned on to replenish water to a section of wastewater; When the liquid level of the wastewater in the middle and upper section is higher than the upper liquid level limit of the wastewater in the middle and upper section and the second pH value meets the requirement, the wastewater discharge unit in the middle and upper section is controlled to drain water.

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