Water and fertilizer returning system and method for returning water and fertilizer to field by applying system

Abstract

The invention discloses a water and fertilizer returning system and a method for returning the system to the field, and the water and fertilizer returning system comprises a liquid discharge device which is used for extracting biogas slurry from a fermentation tank; the sludge discharge device is used for extracting biogas sludge from the fermentation tank; and the mixing device is used for mixing the biogas slurry and the marsh mud according to a set proportion to obtain a mixed solution and returning the mixed solution to the field. According to the water and fertilizer returning system provided by the invention, the sludge discharge device can be used for pumping out the biogas slurry in the fermentation tank, the cleaning efficiency of the biogas slurry is improved, the biogas slurry and the biogas slurry can be mixed and then returned to the field, and thus resource utilization of the biogas slurry is realized.

Description

Technical Field

[0001] The present disclosure generally relates to the field of waste utilization technology. More specifically, the present disclosure relates to a water-fertilizer returning system to a field, and further relates to a method for returning water-fertilizer returning system to a field. Background Art

[0002] In modern animal husbandry, biogas digesters in farms are important environmental protection facilities that are used to treat animal manure and organic waste while generating biogas as a renewable energy source. However, over time, a large amount of sludge will accumulate in the biogas digester, which is mainly composed of the residues after the decomposition of organic matter. The accumulation of sludge will cause the volume of the digester to shrink continuously, affecting the normal operation of the digester and the effective use of water and fertilizer. Therefore, the discharge and treatment of sludge in the digester has become an urgent problem that needs to be solved.

[0003] At present, the commonly used sludge removal technology includes: without emptying the liquid in the pool, uncovering the black film covering the top, and emptying the pool through mechanical excavation and transportation. This method is not only inefficient but also costly. In addition, the cleared sludge is usually transported to a sewage treatment plant for treatment, so that the sludge is not effectively utilized as a resource, resulting in a waste of resources.

[0004] In view of this, there is an urgent need to provide a water and fertilizer returning system and a method for returning water and fertilizer to the field using the system, so as to improve the cleaning efficiency of the sludge in the pond and realize the resource utilization of the sludge. Summary of the invention

[0005] In order to at least solve one or more of the technical problems mentioned above, the present disclosure proposes in multiple aspects a water and fertilizer returning system for returning water and fertilizer to fields that can improve the cleaning efficiency of sludge and a method for returning water and fertilizer to fields using the system.

[0006] In the first aspect, the present disclosure provides a water-fertilizer returning system to the field and the application of the system, which includes: a liquid discharge device, which is used to extract biogas slurry from a fermentation tank; a sludge discharge device, which is used to extract biogas sludge from the fermentation tank; and a mixing device, which is used to mix the biogas slurry and biogas sludge in a set ratio to obtain a mixed liquid, and return the mixed liquid to the field.

[0007] In some embodiments, the water-fertilizer returning system further includes: a storage device for storing the sludge extracted from the fermentation tank by the sludge discharge device, and an agitator is disposed inside the storage device.

[0008] In some embodiments, the drainage device includes a two-phase flow pump and a vacuum tank; the mixing device includes a proportioning pump and a mud pipe, and the proportioning pump pumps the sludge through the mud pipe to the pipeline between the two-phase flow pump and the vacuum tank to mix with the biogas liquid.

[0009] In some embodiments, the water and fertilizer returning system includes N groups of drainage devices; the mud pipe includes a mud pipe main line and N proportioning branches that transport the sludge to the pipeline between the two-phase flow pump and the vacuum tank, and the proportioning branch is provided with a proportioning pump reflux valve, where N is a positive integer not less than 1.

[0010] In some embodiments, the mud discharge device includes a mud suction pipe and a rotor pump, which work together to extract the sludge into a storage device; the water and fertilizer return system also includes a return pipe and a return valve arranged on the return pipe, one end of the return pipe is connected to the storage device, and the other end is connected to the main mud transport pipe.

[0011] In some embodiments, the water-fertilizer returning system also includes: a control system, which is communicatively connected to a mobile terminal, and an electromagnetic flowmeter and a proportioning pump return valve arranged on the proportioning branch; the control system responds to the data detected by the mobile terminal and the electromagnetic flowmeter to control the opening and closing degree of the proportioning pump return valve, so that the biogas liquid and the biogas sludge are mixed in a set ratio.

[0012] In some embodiments, a liquid level detection device is provided in the storage device, and the liquid level detection device is communicatively connected to the control system; the control system controls the start or stop of the rotor pump and / or the start or stop of the proportioning pump in response to data detected by the liquid level detection device.

[0013] In some embodiments, the control system is respectively connected to the N proportioning pump reflux valves in the liquid discharge device and the mobile terminal for communication, and the control system controls different proportioning pump reflux valves to perform opening or closing operations according to control instructions received from the mobile terminal.

[0014] In some embodiments, the rotor pump is connected to M mud pumping pipes through a connecting pipe, and a mud pumping valve is provided on each mud pumping pipe, and an exhaust valve is provided on the connecting pipe, wherein M is a positive integer not less than 1.

[0015] In a second aspect, the present disclosure provides a method for returning water and fertilizer to the field using the above-mentioned water-fertilizer returning system, the method comprising: extracting the biogas slurry from the fermentation tank using a liquid discharge device; extracting the biogas sludge from the fermentation tank using a sludge discharge device; and mixing the extracted biogas slurry with the biogas sludge in a set ratio using a mixing device to obtain a mixed liquid, and returning the mixed liquid to the field.

[0016] Through the water-fertilizer-returning-to-field system provided above, the disclosed embodiment can more conveniently extract the sludge in the fermentation tank by setting a sludge discharge device, thereby improving the sludge cleaning efficiency. Also, by setting a liquid discharge device and a mixing device, the biogas liquid can be extracted from the fermentation tank and mixed with the extracted sludge, and then the mixed liquid can be returned to the field, thereby realizing the resource utilization of the sludge. Furthermore, in some embodiments, a storage device is provided for temporarily storing the sludge extracted from the fermentation tank. Also, since an agitator for stirring the sludge is provided in the storage device, the solid solids in the sludge are prevented from settling, and their uniform distribution in the liquid is maintained to avoid precipitation due to long-term standing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] By reading the detailed description below with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present disclosure will become readily understood. In the accompanying drawings, several embodiments of the present disclosure are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0018] Figure 1 A schematic diagram of a water-fertilizer returning system disclosed in the present invention is shown;

[0019] Figure 2 The sludge ratio control interface in some embodiments of the present disclosure is shown;

[0020] Figure 3 The sludge ratio control interface in some embodiments of the present disclosure is shown.

[0021] In the figure: 100, liquid discharge device; 200, mud discharge device; 300, mixing device; 400, storage device;

[0022] 101. two-phase flow pump; 102. vacuum tank; 103. liquid extraction pipe; 104. liquid discharge pipe;

[0023] 201, rotor pump; 202, mud extraction pipe; 203, mud discharge pipe;

[0024] 301. Proportioning pump; 302. Main mud pipe; 303. Proportioning branch; 304. Proportioning pump reflux valve; 305. Electromagnetic flowmeter; 306. Reflux pipe; 307. Reflux valve. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0026] It should be understood that the terms "include" and "comprising" used in the specification and claims of the present disclosure indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections thereof.

[0027] It should also be understood that the terms used in this disclosure are only for the purpose of describing specific embodiments and are not intended to limit the disclosure. As used in this disclosure and claims, the singular forms of "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It should also be further understood that the term "and / or" used in this disclosure and claims refers to any combination of one or more of the associated listed items and all possible combinations, including these combinations.

[0028] As used in this specification and claims, the term "if" may be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" may be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0029] The specific implementation of the present disclosure is described in detail below with reference to the accompanying drawings.

[0030] In modern animal husbandry, the fermentation tank in the farm is an important environmental protection facility, which is used to treat animal manure and organic waste, and at the same time produce biogas as a renewable energy source. The fermentation tank usually includes an anaerobic tank and a storage tank. During use, animal manure and organic waste first enter the anaerobic tank for fermentation. After the fermentation is completed, the fermentation products flow into the storage tank through the overflow pipe for storage and standby. As time goes by, the amount of biogas slurry and sludge in the storage tank gradually increases. The treatment method of biogas slurry is very simple. It only needs to be pumped out from the storage tank with a centrifugal pump. Because the sludge contains solids, it is usually discharged by excavation with mechanical equipment. This treatment method not only has low treatment efficiency, but also high treatment cost.

[0031] Therefore, the solution disclosed in the present invention provides a water and fertilizer returning system, which can not only use a method different from mechanical equipment to clean up sludge, but also mix sludge and biogas liquid for returning to the fields, thereby realizing resource recycling.

[0032] like Figure 1As shown, in some embodiments, the water-fertilizer returning system includes: a liquid discharge device 100, which is used to extract biogas slurry from a fermentation tank; a sludge discharge device 200, which is used to extract sludge from a fermentation tank; and a mixing device 300, which mixes the biogas slurry and sludge in a set ratio to obtain a mixed liquid, and returns the mixed liquid to the field.

[0033] In this solution, the water and fertilizer returning system includes a liquid discharge device 100, a mud discharge device 200 and a mixing device 300. Specifically, the liquid discharge device 100 includes a liquid discharge pump and a liquid extraction pipe, the mud discharge device 200 includes a mud discharge pump and a mud extraction pipe, and the mixing device 300 includes a proportioning pump and a delivery pipe, wherein the proportioning pump is used to mix the extracted biogas slurry and biogas sludge to obtain a mixed liquid, and then return the mixed liquid to the field. More specifically, the liquid extraction pipe is inserted into the storage tank in the fermentation tank to transport the biogas slurry, and the mud extraction pipe is also inserted into the storage tank in the fermentation tank to transport the biogas sludge.

[0034] In a specific embodiment, the mud discharge device 200 includes a mud discharge pump and a mud suction pipe, wherein the mud discharge pump is a rotor pump 201, and the rotor pump 201 is arranged on the dam of the storage tank. One end of the mud suction pipe 202 is connected to the rotor pump 201, and the other end is inserted into the storage tank for mud extraction. Since the sludge in the storage tank is not evenly distributed, and the sludge with a high solid content is not easy to be extracted, the placement of the mud suction pipe 202 is critical and affects the mud discharge effect. Next, the setting form of the mud suction pipe 202, the method of lowering the pipe, the position of the lowering pipe, and the judgment criteria for detecting whether the lowering pipe meets the set requirements are introduced in detail.

[0035] Before laying the pipe, first select a 6-meter-long PVC pipe and open a hole with a diameter of 3CM on the pipe according to the design requirements. Add a plug at one end of the pipe and open two holes with a diameter of 3CM on the plug. After the holes are opened, clean out the debris in the pipe. Next, connect the pipe to the pipe with a large head through an elbow, that is, use a 45° elbow to connect the PVC pipe with the hole to the 2-meter-long pipe with a large head. When connecting, make sure the elbow and pipe are fully inserted and fixed with glue. The connection needs to be still for more than 24 hours to ensure that the glue is completely cured.

[0036] Next, we will start to detect the location of the lower pipe, that is, use the probe to determine the location of the additional pipe. When detecting, we mainly detect the positions on the left and right sides of the overflow pipe, because these positions are the main areas of sludge flow. The sludge within 20 meters on both sides of the field return pipe has poor fluidity and is generally not used as a detection position. The starting position of the detection should be at least 10 meters away from the overflow pipe to avoid extracting sludge with too high a solid content. The lower pipe point is determined based on the detection results, and a detection point (i.e., lower pipe point) should be set every 10-15 meters.

[0037] After determining the location of the additional pipeline, the next step is to lower the pipeline. Push the prefabricated PVC (polyvinyl chloride) pipeline into the storage pool. When the pipeline is about 1 meter left on the dam slope, glue a new PVC pipeline and make sure that the glued part solidifies for 30 minutes before continuing to push it into the pool. When the pipeline touches the mud layer, you will feel resistance. At this time, you need to observe whether the PP rope left on the shore is synchronously entering the bottom of the pool to determine the status of the pipeline at the bottom of the pool.

[0038] After the pipe is lowered, determine whether the pipe is added successfully based on the set conditions. The set conditions in this solution are that the rotor pump can stably pump sludge for more than 20 minutes, and can still stably pump for more than 20 minutes the next day. When the set conditions are met, it means that the pipe is added successfully. If the set conditions are not met, it means that the pipe is not added successfully, and it is necessary to re-determine the pipe lowering position and lower the pipe until the pipe can meet the set conditions.

[0039] In the solution provided in this embodiment, the mud discharge device 200 is not only provided with one mud pumping pipe 202, but multiple mud pumping pipes 202 are provided as needed, and a PVC ball valve with a diameter of 160 mm is provided for each newly added mud pumping pipe 202. In addition, the newly added mud pumping pipes 202 are connected by PVC pipes with a diameter of 110 mm, and an exhaust and water injection valve is provided at the highest point.

[0040] In the solution provided in this embodiment, more than one rotor pump 201 is provided, and multiple rotor pumps 201 may be provided according to actual usage conditions. In addition, each rotor pump 201 is connected to M mud pumping pipes 202 via a connecting pipe, and a mud pumping valve is provided on each mud pumping pipe 202, and an exhaust valve is provided on the connecting pipe. In the solution of this embodiment, M is a positive integer not less than 1.

[0041] In some specific implementation schemes, one rotor pump 201 carries 2-3 additional mud pumping pipes 202, and the rotor pump 201 is located in the middle area of ​​the mud pumping pipes 202. For example, when the rotor pump 201 drives two mud pumping pipes 202, it is arranged in the middle of the two mud pumping pipes 202, and the distance from any mud pumping pipe 202 does not exceed 10 meters.

[0042] In addition, in the disclosed solution, the mud discharge device 200 is also provided with a rotor pump return pipe, on which a rotor pump return valve is provided. Specifically, one end of the rotor pump return pipe is connected to the mud discharge pipe 203 between the rotor pump 201 and the storage device 400, and the other end is connected to the storage tank.

[0043] Those skilled in the art will appreciate that information such as the number, length, material of the mud extraction pipes, the size of the openings, the distance between the mud extraction pipes, the number of rotor pumps, and the number of mud extraction pipes connected to each rotor pump in the above scheme are exemplary rather than restrictive, and in actual use, those skilled in the art may adjust and replace them according to actual conditions.

[0044] In a specific embodiment, the water and fertilizer returning system also includes a storage device 400, which is connected to the mud discharge pipe 203 in the mud discharge device 200. That is, one end of the mud discharge pipe 203 is connected to the rotor pump 201, and the other end is connected to the storage device 400. An agitator is provided inside the storage device 400, and it is used to store the sludge extracted from the storage tank by the mud discharge device 200. Specifically, the storage device 400 is a storage tank, and an agitator is provided in the storage tank. An ultrasonic level meter is installed in the opening on the top of the storage tank, wherein the agitator is used to stir the sludge in the storage tank to prevent solid sedimentation, and the liquid level detection device is used to detect the liquid level in the storage tank in real time, and an alarm is issued when the liquid level reaches or approaches the upper limit of the storage tank capacity, thereby preventing overflow, avoiding environmental pollution and equipment damage. When the liquid level reaches or approaches the lower limit of the storage tank capacity, an alarm is issued, thereby preventing the situation where the sludge in the storage tank is insufficient and the sludge is still output from the storage tank.

[0045] More specifically, in order to reduce energy loss during transportation and control costs, the storage tank is set up near the storage pool. Since the storage pool is surrounded by soil, when the storage tank is filled with sludge, its weight will increase, and the lower end of the storage tank will sink into the soil, which may cause the storage tank to tilt and pose a safety hazard. Therefore, a cement platform is set up for placing the storage tank. The cement platform can provide a solid support foundation for the storage tank in the horizontal direction, reducing the tilt or instability caused by uneven or softened ground.

[0046] In the solution provided in this embodiment, since the sludge generated in the storage tank may not be continuous and uniform, the sludge in the storage tank is pumped into the storage tank for temporary storage by using the sludge discharge device for subsequent processing. This setting method can also mix the biogas liquid and the sludge according to the set ratio.

[0047] The above scheme introduces the mud discharge device 200 and the storage device 400 in detail, and the liquid discharge device 100 and the mixing device 300 are introduced in detail next.

[0048] In a specific embodiment, the drainage device 100 includes a two-phase flow pump 101 and a vacuum tank 102, a suction pipe 103 and a drainage pipe 104 connected by a pipeline, wherein one end of the suction pipe 103 is inserted into the storage tank, and the other end is connected to the vacuum tank 102, one end of the drainage pipe 104 is connected to the two-phase flow pump 101, and the other end is connected to a collection device or a field return device.

[0049] When in use, the biogas slurry in the storage tank is pumped out through the suction pipe 103 under the action of the two-phase flow pump 101 and the vacuum tank 102, and then enters the collection equipment through the discharge pipe 104 for collection or enters the field returning equipment for direct field return.

[0050] It is worth noting that the water-fertilizer returning system provided in this solution is not provided with only one set of drainage devices 100, and N sets of drainage devices 100 can be provided as needed, where N is a positive integer greater than or equal to 1.

[0051] The drainage pump in the drainage device 100 provided in this embodiment is a two-phase flow pump 101, so that the biogas slurry can be better pumped out from the storage tank.

[0052] In a specific embodiment, the mixing device 300 is connected to the liquid discharge device 100 and the mud discharge device 200 respectively, and its function is to transport the sludge extracted from the mud discharge device 200 to the pipeline of the liquid discharge device 100 through a pipeline for mixing to obtain a mixed liquid. Specifically, the mixing device 300 includes a proportioning pump 301 and a delivery pipe, wherein the delivery pipe includes a mud discharge pipe 203 and a mud delivery pipe. One end of the mud discharge pipe 203 is connected to the storage tank, and the other end is connected to the inlet of the proportioning pump 301. One end of the mud delivery pipe is connected to the outlet of the proportioning pump 301, and the other end is connected to the pipeline in the liquid discharge device 100. More specifically, since the sludge in the sludge pipe contains a large amount of solids, if the other end of the sludge pipe is connected to the liquid extraction pipe 103, the solids will not only block the pipe, but may also damage the vacuum pump. Therefore, the solution adopted in this embodiment is to connect the other end of the sludge pipe to the pipe between the two-phase flow pump 101 and the vacuum tank 102. That is to say, the proportioning pump 301 transports the sludge in the storage tank through the sludge pipe to the pipe between the two-phase flow pump 101 and the vacuum tank 102 of the drainage device 100 to mix with the biogas liquid.

[0053] In this solution, since N groups of drainage devices 100 are provided, the sludge in the storage device needs to be transported to the corresponding drainage devices 100, so a plurality of pipes connecting the drainage devices 100 and the storage device are provided. Specifically, the sludge delivery pipe includes a sludge delivery pipe main line 302 and a proportioning branch line 303 of the same number as the drainage devices 100, and each proportioning branch line 303 is provided with an electromagnetic flowmeter 305 and a proportioning pump return valve 304, wherein the electromagnetic flowmeter 305 is used to detect the flow of the sludge flowing through the branch line. The proportioning pump return valve 304 is used to open and close the branch line, and to adjust the flow of the sludge flowing through the branch line by controlling the size of its opening and closing. More specifically, the mud pipe main line 302 serves as a main pipeline and is connected to the storage tank. One end of the proportioning branch line 303 is connected to the mud pipe main line 302 , and the other end is connected to the pipeline between the two-phase flow pump 101 and the vacuum tank 102 in the discharge device 100 .

[0054] In order to enable those skilled in the art to better understand the arrangement of the mud pipe in this solution, an example is given below. For example, in a water-fertilizer returning system, four groups of drainage devices 100 and one group of mixing devices 300 are arranged in parallel, wherein the mixing device 300 is arranged between the four groups of drainage devices 100. In other words, there are two groups of drainage devices 100 on each side of the mixing device 300. Specifically, the mixing device 300 includes a mud pipe main line 302 and four proportioning branches 303, wherein one end of the four proportioning branches 303 is connected to the mud pipe main line 302, and the other end is connected to the corresponding drainage device 100.

[0055] When in use, the mixing device 300 transports the sludge in the storage tank to the main road of the sludge discharge pipe 203, and then transports it to the corresponding discharge device 100 through the proportioning branch 303 connected to the main road of the sludge discharge pipe 203. In addition, since the proportioning pump return valve 304 is provided on the proportioning branch 303, when a certain discharge device 100 does not need to be mixed with the sludge, it is only necessary to close the proportioning pump return valve 304 on the proportioning branch 303 connected to the discharge device 100. When the flow of the proportioning branch 303 needs to be adjusted, the opening degree of the proportioning pump return valve 304 is controlled according to the data detected by the electromagnetic flowmeter 305 to achieve the sludge flow in the proportioning branch 303.

[0056] Those skilled in the art can understand that the number of mixing devices 300 can be adjusted according to the number of drainage devices 100. If the number of drainage devices 100 is large, the power of a group of mixing devices 300 is insufficient to transport the sludge to all drainage devices 100. In this way, the number of mixing devices 300 can be increased, thereby improving the transportation efficiency of the mixing devices 300.

[0057] It is worth noting that in the solution provided by the present disclosure, in addition to the storage tank, a proportioning pump 301 is also placed on the cement platform. When in use, the cement platform provides a stable support force for the proportioning pump 301 to ensure that the proportioning pump 301 can run smoothly. In addition, the size of the cement platform can be set according to the size of the storage tank and the size of the proportioning pump 301. In a specific embodiment, the size of the cement platform can be set to a rectangular shape with a length of 2.5 meters, a width of 4 meters, and a height of 0.2 meters. It will be understood by those skilled in the art that the size of the cement platform is exemplary and not restrictive, and can be set according to actual conditions during production.

[0058] In a specific embodiment, the mixing device 300 further includes a return pipe 306 and a return valve 307 disposed on the return pipe 306. Specifically, one end of the return pipe 306 is connected to the storage device, and the other end is connected to the main mud delivery pipe 302.

[0059] In this solution, a return pipe 306 is provided so that the sludge in the downstream sludge pipe can flow back to the upstream storage tank. A return valve 307 is provided in the return pipe 306 to balance the flow of the entire system and avoid system instability caused by excessive or insufficient flow.

[0060] The water and fertilizer returning system also includes a control system, which is connected to the mobile terminal, the mud discharge device 200 and the mixing device 300 for communication. Specifically, a command input area is provided on the mobile terminal. When in use, the user inputs an operation command in the command input area, and the control system sends a control command to the mud discharge device 200 or the mixing device 300 according to the received operation command, and the mud discharge device 200 or the mixing device 300 operates according to the received control command.

[0061] In one embodiment, the control system is communicated with a liquid level detection device provided on the storage tank and a rotor pump 201 in the mud discharge device 200. The control system sends a start or stop control instruction to the rotor pump 201 based on the data detected by the liquid level detection device, and the rotor pump 201 operates according to the received control instruction.

[0062] In this embodiment, the function of the rotor pump 201 is to pump the sludge in the storage pool into the storage tank. If there is too much sludge in the storage tank, the liquid in the storage tank will overflow if the rotor pump 201 continues to operate, which not only makes the resources not reasonably utilized, but also pollutes the environment. If the amount of sludge in the storage tank is small, the rotor pump 201 can be started to pump the sludge.

[0063] like Figure 3As shown, in a specific embodiment, the liquid level at which the rotor pump 201 starts can be set to 50 cm, and the liquid level at which the rotor pump 201 stops can be set to 160 cm. Of course, those skilled in the art will appreciate that the above values ​​are exemplary rather than restrictive, and those skilled in the art can make appropriate adjustments based on actual conditions.

[0064] In one embodiment, the control system is also in communication with the proportioning pump 301. In this embodiment, the control system sends a start or stop control instruction to the proportioning pump 301 according to the data detected by the liquid level detection device, and the proportioning pump 301 operates according to the received control instruction.

[0065] In this embodiment, the proportioning pump 301 is used to transport the sludge in the storage tank to the pipeline of the liquid discharge device 100. If the liquid in the storage tank is too little, it cannot meet the supply, and the proportioning pump 301 will run idle at this time, which affects its service life. Therefore, in this solution, the operation of the proportioning pump 301 is controlled according to the liquid level in the storage tank.

[0066] In a specific embodiment, the liquid level at which the proportioning pump 301 stops can be set to 40 cm, and the liquid level at which the proportioning pump 301 starts can be set to 130 cm. Of course, those skilled in the art will appreciate that the above values ​​are exemplary rather than restrictive, and those skilled in the art can make appropriate adjustments based on actual conditions.

[0067] like Figure 2 As shown, a limit liquid level value is set for the storage tank. In a specific embodiment, the limit liquid level value of the storage tank is 160 cm. In the scheme disclosed herein, by setting the limit liquid level, the liquid can be prevented from exceeding the maximum capacity of the storage tank, thereby avoiding overflow, reducing environmental pollution and potential safety hazards.

[0068] In one embodiment, the control system is in communication with a proportioning pump reflux valve disposed on a proportioning branch, and controls the corresponding proportioning branch to be opened or closed in response to a control instruction sent by a user on a mobile terminal.

[0069] like Figure 1 As shown, the user selects on the mobile terminal whether to turn on "branch one proportioning" and whether to turn on "branch two proportioning" control instructions, and then the proportioning pump reflux valve on the proportioning branch in the mixing device is opened or closed according to the received control instructions. In this solution, "branch one proportioning" refers to the first proportioning branch in the mixing device, and "branch two proportioning" refers to the second proportioning branch in the mixing device. When the user selects "branch one proportioning" to turn on and "branch two proportioning" to turn off, the proportioning pump reflux valve on the first proportioning branch in the mixing device is controlled to open, and the proportioning pump reflux valve on the second proportioning branch is controlled to close.

[0070] In one embodiment, the control system is in communication with the electromagnetic flowmeter 305 and the proportioning pump return valve 304 provided on the proportioning branch 303. The control system controls the opening and closing degree of the proportioning pump return valve 304 in response to the data detected by the electromagnetic flowmeter 305, so that the biogas liquid and the biogas sludge are mixed according to the set ratio.

[0071] In this solution, after the user inputs a ratio of biogas liquid to sludge on the mobile terminal, the electromagnetic flowmeter 305 detects the flow of sludge in the proportioning branch 303, and then transmits the data to the control system. The data processing module in the control system determines the opening degree of the proportioning pump return valve 304 according to the flow rate of biogas liquid and the flow rate of sludge, and then issues a control instruction. The proportioning pump return valve 304 adjusts its opening degree according to the control instruction.

[0072] It is worth noting that, in the solution disclosed herein, the flow rate of the biogas liquid is set as known data, and the ratio of the two can be obtained by simply detecting the flow rate of the biogas sludge.

[0073] It will be understood by those skilled in the art that the above Figure 2 and Figure 3 The content is exemplary and not restrictive, and multiple proportioning branches 303 can be set.

[0074] In one embodiment, the ratio of biogas slurry and biogas sludge is determined according to the soil nutrition conditions that need to be returned to the field, as well as the content of trace elements in biogas slurry and biogas sludge. Specifically, representative sampling points are selected for sampling, and the collected soil samples are sent to the laboratory for detailed chemical analysis, including pH value, organic matter content, and the content of major nutrients such as nitrogen, phosphorus, and potassium, so as to gain a preliminary understanding of the nutritional status of the soil. The biogas slurry and biogas sludge are then sent to the laboratory for testing and analysis to determine the content of nutrients such as nitrogen, phosphorus, and potassium, as well as possible heavy metals and other pollutants. The required amount of nutrients is evaluated according to the needs of the soil and crops. Then, combined with the test results of soil, biogas sludge and biogas slurry, a suitable formula for returning to the field is calculated to ensure that crops can get adequate nutrition while avoiding environmental pollution caused by excessive application. In addition, if the test results show that the pH value of the biogas slurry or biogas sludge is not suitable, it needs to be adjusted by adding substances such as lime or sulfuric acid.

[0075] After the mixing ratio of biogas slurry and biogas sludge is determined, the two are mixed according to the ratio to obtain a mixed liquid, and then the mixed liquid is returned to the field. After the return to the field is completed, it is necessary to conduct a return to the field test on the field, such as observing the growth response of crops and changes in the soil. Collect test data, including crop growth, soil nutritional status, etc. According to the test results and data analysis, make necessary adjustments to the return to the field formula.

[0076] The water and fertilizer returning system provided by the present disclosure can remove the sludge in the biogas pool more efficiently by adding sludge discharge facilities, without the need for large-scale machinery intervention, omitting the traditional film removal, transportation and processing steps, and reducing the consumption of manpower and material resources. The sludge is mixed with water and fertilizer in proportion and returned to the field, realizing the resource utilization of sludge, improving soil fertility, and promoting the sustainable development of agriculture.

[0077] In some embodiments, the present disclosure also provides a method for returning water and fertilizer to the field using the above-mentioned water and fertilizer returning system, the method comprising: using a liquid discharge device 100 to extract the biogas slurry from the fermentation tank; using a sludge discharge device 200 to extract the sludge from the fermentation tank; and using a mixing device 300 to mix the extracted biogas slurry with the sludge in a set ratio to obtain a mixed liquid, and returning the mixed liquid to the field.

[0078] In the method of returning water and fertilizer to the field disclosed in the present invention, not only can the sludge in the fermentation tank be extracted by the sludge discharge device 200, thereby improving the sludge cleaning efficiency, but the sludge and biogas liquid can also be mixed and returned to the field, thereby realizing the resource utilization of the sludge.

[0079] Although multiple embodiments of the present disclosure have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Those skilled in the art may think of many changes, modifications, and alternatives without departing from the thought and spirit of the present disclosure. It should be understood that in the process of practicing the present disclosure, various alternatives to the embodiments of the present disclosure described herein may be adopted. The attached claims are intended to define the scope of protection of the present disclosure, and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. A water and fertilizer returning system, characterized in that: include: A liquid discharge device, which is used to extract biogas slurry from the fermentation tank; A sludge discharge device, which is used to extract sludge from the fermentation tank; as well as The mixing device is used to mix the biogas slurry and biogas sludge in a set ratio to obtain a mixed liquid, and return the mixed liquid to the field.

2. The system according to claim 1, characterized in that The water-fertilizer returning system also includes: The storage device is used to store the biogas sludge extracted from the fermentation tank by the sludge discharge device, and a stirrer is arranged inside the storage device.

3. The system according to claim 1 or 2, characterized in that: The liquid discharge device comprises a two-phase flow pump and a vacuum tank; The mixing device comprises a proportioning pump and a mud delivery pipe. The proportioning pump pumps the biogas sludge through the mud delivery pipe to a pipeline between the two-phase flow pump and the vacuum tank to mix with the biogas liquid.

4. The system according to claim 3, characterized in that The water and fertilizer returning system includes N sets of drainage devices; The mud delivery pipe includes a mud delivery pipe main line and N proportioning branches that transport the sludge to the pipeline between the two-phase flow pump and the vacuum tank, and the proportioning branch is provided with a proportioning pump reflux valve, wherein N is a positive integer not less than 1.

5. The system according to claim 4, characterized in that The mud discharge device includes a mud pumping pipe and a rotor pump, which work together to extract the sludge into the storage device; The water-fertilizer returning system also includes a return pipe and a return valve arranged on the return pipe. One end of the return pipe is connected to the storage device, and the other end is connected to the main mud conveying pipe.

6. The system according to claim 5, characterized in that The water-fertilizer returning system also includes: A control system is communicatively connected with a mobile terminal, and an electromagnetic flowmeter and a proportioning pump return valve arranged on the proportioning branch; the control system responds to data detected by the mobile terminal and the electromagnetic flowmeter to control the opening and closing degree of the proportioning pump return valve, so that the biogas liquid and the biogas sludge are mixed according to the set ratio.

7. The system according to claim 6, characterized in that A liquid level detection device is provided in the storage device, and the liquid level detection device is communicatively connected with the control system; The control system controls the start or stop of the rotor pump and / or the start or stop of the proportioning pump in response to the data detected by the liquid level detection device.

8. The system according to claim 6, characterized in that The control system is respectively connected to the N proportioning pump reflux valves in the liquid discharge device and the mobile terminal for communication, and the control system controls different proportioning pump reflux valves to perform opening or closing operations according to control instructions received from the mobile terminal.

9. The system according to claim 4, characterized in that The rotor pump is connected to M mud pumping pipes through a connecting pipe, and a mud pumping valve is arranged on each mud pumping pipe, and an exhaust valve is arranged on the connecting pipe, wherein M is a positive integer not less than 1.

10. A method for returning water and fertilizer to fields using the water and fertilizer returning system according to any one of claims 1 to 9, characterized in that: include: The biogas slurry is pumped out of the fermentation tank by using the drainage device; The sludge is pumped out of the fermentation tank by using the sludge discharge device; as well as The extracted biogas liquid and biogas sludge are mixed with each other in a set ratio by using a mixing device to obtain a mixed liquid, and the mixed liquid is returned to the field.

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