System for directly returning biogas residues to field and use method

Abstract

The invention discloses a system for directly returning biogas residues to fields and a using method, and relates to the technical field of livestock breeding, the system for directly returning the biogas residues to the fields is used for pumping biogas slurry in a biogas digester and returning the biogas slurry to the fields, and comprises a plurality of mud pumping pipelines, a mixing pipeline, a water fertilizer pumping pipeline, a controller, a mud discharging pump and a mud discharging pipeline, the sludge pumping pipelines are arranged at the bottom of the biogas digester and all communicated with the mixing pipeline, the sludge discharging pipeline is communicated with an outlet of the sludge discharging pump, the mixing pipeline is communicated with an inlet of the sludge discharging pump, the water fertilizer pumping pipeline is arranged in the biogas digester and communicated with the mixing pipeline, and the controller is used for controlling the opening degree of the sludge pumping pipelines and the opening degree of the water fertilizer pumping pipeline. By reasonably mixing the biogas slurry and the biogas slurry with higher solid content, the biogas slurry at the bottom of the biogas digester can be quickly cleaned and returned to the field, the effective volume of the digester is increased, the temporary storage time of the biogas residues is prolonged, the biogas residues are reasonably applied to the land, the weight loss and income increase of crops are facilitated, and the resource utilization is realized.

Description

Technical Field

[0001] The present invention relates to the field of animal husbandry technology, and more specifically, to a system for directly returning biogas residue to fields. Furthermore, the present invention also relates to a method for using the system. Background Art

[0002] Manure from livestock farms typically enters a biogas storage tank after solid-liquid separation. These tanks are often sealed with a membrane. Within these tanks, the solid-liquid separation produces biogas, while the biogas residue accumulates. To increase the tank's storage capacity, the biogas residue must be removed. Anaerobic fermentation of the biogas residue is rich in nitrogen, phosphorus, and potassium. Proper application to the land can help increase crop yields and revenue, thus realizing resource utilization.

[0003] At present, the method of removing sludge is mostly to use mechanical methods such as excavators. When cleaning, the top membrane needs to be removed and the water in the pool needs to be drained before the excavator can clean it. However, the pool needs to be filled with water all the time, and it is difficult to empty the water. The pool body is above the ground and it is not easy for machinery to enter. In addition, the cost of using an excavator for cleaning is high. At the same time, the sludge cleaned out by the excavator needs to be returned to the field mechanically, which increases the transportation cost.

[0004] In summary, how to provide a low-cost system for cleaning the biogas residue in the biogas tank and returning it to the field is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a direct return system for biogas residues to the fields, which can continuously extract the biogas liquid in the biogas pool and spray it on the fields, so as to fully utilize the resources and reduce the cost of cleaning the biogas pool.

[0006] Another object of the present invention is to provide a method of use, which is applicable to the above-mentioned biogas residue direct return to farmland system.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A biogas residue direct return system is used to extract biogas liquid from a biogas tank and return it to the field, comprising:

[0009] A plurality of mud extraction pipes are provided at the bottom of the biogas tank;

[0010] A mixing pipe, wherein a plurality of mud extraction pipes are connected to the mixing pipe;

[0011] A mud discharge pump and a mud discharge pipe, wherein the mud discharge pipe is connected to the outlet of the mud discharge pump, and the mixing pipe is connected to the inlet of the mud discharge pump;

[0012] A water and fertilizer pumping pipeline is arranged in the biogas tank and is connected to the mixing pipeline;

[0013] A controller is used to control the opening of the mud pumping pipeline and the water and fertilizer pumping pipeline.

[0014] The present invention further includes:

[0015] A mud discharge pump is connected to the pipe network, and the mud discharge pipeline is connected to the outlet or inlet of the mud discharge pump.

[0016] The present invention further includes:

[0017] The first flow meter is installed in the fertilizer pumping pipeline and is used to detect the flow of the fertilizer pumping pipeline. The first flow meter is electrically connected to the controller.

[0018] The present invention further includes:

[0019] The second flow meter is installed in the mud discharge pipeline and is used to detect the flow of the mud discharge pipeline. The second flow meter is electrically connected to the controller.

[0020] The present invention further includes:

[0021] A pressure sensor is installed in the mud discharge pipeline and is used to detect the pressure of the mud discharge pipeline. The pressure sensor is electrically connected to the controller.

[0022] The present invention further includes:

[0023] A return pipe, one end of which is connected to the mud discharge pipe, and the other end of which is connected to the biogas tank.

[0024] The present invention further provides that several of the mud pumping pipes are provided with mud pumping valves, the return pipe is provided with a return valve, and the water and fertilizer pumping pipe is provided with a water and fertilizer valve, and the mud pumping valves, return valves and water and fertilizer valves are all electrically connected to the controller.

[0025] Furthermore, the present invention is provided with a stop valve on the mud discharge pipeline, and the stop valve is located on a side of the return pipeline away from the mud discharge pump.

[0026] A method of use, applied to the above-mentioned biogas residue direct return to farmland system;

[0027] Several mud pumping valves are opened in turn, and each opening lasts for 1 hour;

[0028] When the pressure sensor reaches the preset value, the fertilizer pumping pipeline is opened to reduce the solid content in the mixing pipeline and thus reduce the pipeline pressure;

[0029] When the flow rate detected by the second flow meter is lower than 20m³ / h, the sludge pump stops working, the return pipe is opened, and the sludge pump reverses to extract the supernatant from the biogas tank through the return pipe to backwash several sludge extraction pipes in turn;

[0030] After the backwash is completed, the sludge pump stops working, the reflux valve is closed, the sludge pump rotates forward, and the second flow meter continuously detects the flow rate;

[0031] If the flow rate increases, the mud pump 4 continues to work in the forward direction;

[0032] If the flow rate is lower than 20m³ / h, the system will shut down and sound an alarm.

[0033] The present invention further has the following advantages: after returning the soil to the field is completed, all mud pumping valves are closed, and the water and fertilizer valves and the mud discharge pump are opened at the same time for a preset time.

[0034] The biogas residue direct return system provided by the present invention places a plurality of mud pumping pipes at the bottom of the biogas tank for extracting biogas residue with a high solid content. During the extraction, the pipes are used to pump water and fertilizer, and under the action of the controller, the solid content of the biogas liquid entering the mixing pipe and the mud pump reaches a preset value. Specifically, the controller controls the opening of the mud pumping pipe and the water and fertilizer pumping pipe, thereby controlling the solid content of the biogas liquid in the mixing pipe, realizing rapid and continuous extraction and return of the biogas liquid in the biogas tank to the field, reducing the content of the biogas liquid at different positions in the biogas tank, cleaning a large amount of biogas residue, increasing the effective pool capacity of the pool, increasing the buffering time of the biogas residue, and rationally applying it to the land, which is beneficial to the weight loss and income increase of crops and realizing resource utilization.

[0035] A method of use is applied to the above-mentioned biogas residue direct return to field system, and has the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0037] Figure 1 This is a schematic diagram of the structure of the system provided by the present invention when in use;

[0038] Figure 2 This is a partial structural diagram of the mud pump provided by the present invention;

[0039] Figure 3 This is a schematic diagram of the structure of a portion of the delivery pump provided by the present invention.

[0040] Figure 1-Figure 3, the reference numerals include:

[0041] 1. Biogas tank; 2. Mud extraction pipeline; 3. Mixing pipeline; 4. Mud discharge pump; 5. Mud discharge pipeline; 6. Pressure sensor; 7. Mud extraction valve; 8. Water and fertilizer extraction pipeline; 9. Water and fertilizer valve; 10. First flow meter; 11. Return valve; 12. Return pipe; 13. Second flow meter; 14. Delivery pump. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0043] The core of the present invention is to provide a system for directly returning biogas residue to the fields, which can continuously extract the biogas liquid in the biogas tank 1 and spray it on the fields, thereby fully utilizing resources and reducing the cost of cleaning the biogas tank 1.

[0044] Another core of the present invention is to provide a method of use, which is applied to the above-mentioned biogas residue direct return to farmland system.

[0045] Please refer to Figure 1 A direct return system for biogas residue to the field is used to extract biogas liquid from a biogas tank 1 and return it to the field. It includes several mud extraction pipes 2, a mixing pipe 3, a water and fertilizer extraction pipe 8, a controller, a mud pump 4 and a mud discharge pipe 5. Several mud extraction pipes 2 are arranged at the bottom of the biogas tank 1, and several mud extraction pipes 2 are connected to the mixing pipe 3. The mud discharge pipe 5 is connected to the outlet of the mud discharge pump 4, and the mixing pipe 3 is connected to the inlet of the mud discharge pump 4. The water and fertilizer extraction pipe 8 is arranged in the biogas tank 1 and connected to the mixing pipe 3. The controller is used to control the opening of the mud extraction pipe 2 and the water and fertilizer extraction pipe 8.

[0046] It should be noted that, in the embodiment of the present invention, the plurality of mud extraction pipes 2, the mixing pipe 3, the water and fertilizer extraction pipe 8 and the mud discharge pipe 5 can all be made of PE or PVC.

[0047] In addition, in the embodiment of the present invention, valves may be provided on the mud pumping pipe 2 and the water and fertilizer pumping pipe 8, and the controller controls the ratio of the biogas slurry and the water and fertilizer by controlling the opening of the valves.

[0048] Optionally, in some embodiments, a plurality of mud extraction pipes 2 are placed at the bottom of the biogas tank 1 , and counterweights are installed on the mud extraction pipes 2 .

[0049] In the above embodiment, the ends of the plurality of mud pumping pipes are provided with screens to prevent larger debris from entering the mud pumping pipes.

[0050] Optionally, in some embodiments, the water-fertilizer pumping pipe 8 is arranged along the wall of the biogas tank 1 and extends into the position of two-thirds of the side wall of the biogas tank 1 .

[0051] Optionally, in some embodiments, the return pipe 12 is arranged along the wall of the biogas tank 1 and extends into the biogas tank 1 to a position of one meter of the side wall.

[0052] Alternatively, in some embodiments, the mud pump 4 may be a rotor pump.

[0053] During use, several mud extraction pipes 2 are placed at the bottom of the biogas tank 1 to extract biogas sludge with a high solid content. When extracting, they are coordinated with the water and fertilizer extraction pipes 8, and under the action of the controller, the solid content of the biogas liquid entering the mixing pipe 3 and the mud pump 4 reaches a preset value. Specifically, the controller controls the opening of the mud extraction pipe 2 and the water and fertilizer extraction pipe 8, thereby controlling the solid content of the biogas liquid in the mixing pipe 3, realizing rapid and continuous extraction and return of the biogas liquid in the biogas tank 1 to the field, reducing the content of biogas liquid at different positions in the biogas tank 1, cleaning a large amount of biogas residue, increasing the effective pool capacity of the pool, increasing the buffering time of biogas residue, and reasonably applying it to the land, which is beneficial to the weight loss and income increase of crops and realizing resource utilization.

[0054] Please refer to Figure 3 In some embodiments, a delivery pump 14 is also included. The delivery pump 14 is connected to the pipeline network, and the mud discharge pipe 5 is connected to the outlet or inlet of the delivery pump 14. That is to say, the biogas slurry is delivered into the farmland pipeline network through the delivery pump 14, and the biogas slurry is returned to the field through the pipeline network. The delivery pump 14 is used to increase the delivery distance of the biogas slurry.

[0055] In the above embodiment, the sludge pump 4 is used to extract the biogas slurry into the sludge pipe 5. When the power of the sludge pump 4 is low, the outlet position of the sludge pipe 5 can be connected to the inlet end of the delivery pump 14 to increase the delivery distance of the biogas slurry through the inlet end. When the power of the sludge pump 4 is high and meets the delivery distance requirements, the outlet position of the sludge pipe 5 can be connected to the outlet end of the delivery pump 14.

[0056] In the above embodiment, a Y-shaped pipe is provided on the delivery pump 14, and the two outlet positions of the Y-shaped pipe are respectively connected to the inlet end and the outlet end of the delivery pump 14, and the inlet end of the Y-shaped pipe is connected to the sludge discharge pipe 5, and an electromagnetic three-way valve is provided on the Y-shaped pipe, which controls the entry of the biogas slurry into the inlet end or the outlet end of the delivery pump 14, and the triggering condition of the electromagnetic three-way valve is determined according to the flow rate and pressure of the sludge discharge pipe 5. When the flow rate and pressure are reduced to the preset value, the electromagnetic three-way valve opens one end of the inlet end of the delivery pump 14, thereby increasing the delivery distance through the delivery pump 14.

[0057] Please refer to Figure 2In some embodiments, a first flow meter 10 is further included. The first flow meter 10 is installed in the water and fertilizer pumping pipeline 8 and is used to detect the flow of the water and fertilizer pumping pipeline 8. The first flow meter 10 is electrically connected to the controller, and the flow of water and fertilizer is monitored through the first flow meter 10.

[0058] Please continue to refer to Figure 2 In some embodiments, a second flowmeter 13 is further included. The second flowmeter 13 is installed in the sludge discharge pipe 5 and is used to detect the flow in the sludge discharge pipe 5. The second flowmeter 13 is electrically connected to the controller. The flow in the sludge discharge pipe 5 is monitored by the second flowmeter 13. At the same time, the first flowmeter 10 and the second flowmeter 13 are both electrically connected to the controller, so the controller can control the opening of the water and fertilizer pumping pipe 8 and the sludge pumping pipe 2 according to the flow detected by the first flowmeter 10 and the second flowmeter 13, thereby realizing the control of the solid content of the biogas slurry in the mixing pipe 3.

[0059] In the above embodiment, it was tested that when the solid content is below 7%, the efficiency of mud and water extraction will not decrease.

[0060] Optionally, some embodiments further include a pressure sensor 6 , which is installed in the sludge discharge pipeline 5 and is used to detect the pressure in the sludge discharge pipeline 5 . The pressure sensor 6 is electrically connected to the controller. In other words, the pressure in the sludge discharge pipeline 5 is monitored by the pressure sensor 6 . When the outlet pressure of the sludge discharge pump 4 is excessive, the pressure sensor 6 provides a feedback signal to the PLC, which in turn reduces the speed of the sludge discharge pump 4 to ensure constant pressure mud supply. The controller has a preset upper limit for pipeline pressure (preset value), which can be overwritten using a mobile phone or the controller panel.

[0061] In the above embodiment, the protection pressure value of the PVC pipe network should not be higher than 0.45MP, and the protection pressure value of the PE pipe network should not be higher than 0.6MP.

[0062] Please refer to Figure 2 In some embodiments, a return pipe 12 is further included, one end of which is connected to the mud discharge pipe 5, and the other end of the return pipe 12 is connected to the biogas tank 1. The return pipe 12 is used to backflush the mud pumping pipe. When the flow rate of the mud pumping pipe is low, it is determined that a blockage has occurred. At this time, the return pipe 12 is opened to backflush the mud pumping pipe, thereby ensuring that the mud pumping pipe is always unobstructed.

[0063] In the above embodiment, when the flow rate monitored by the second flow meter 13 is lower than 20m³ / h, the reason may be that the solid content is too high or the mud discharge hole of the mud discharge pipe 5 is blocked by garbage, so the backwash through the return pipe 12 can solve the problem.

[0064] Optionally, in some embodiments, several of the mud pumping pipes 2 are provided with mud pumping valves 7, the return pipe 12 is provided with a return valve 11, and the water and fertilizer pumping pipe 8 is provided with a water and fertilizer valve 9. The mud pumping valve 7, the return valve 11 and the water and fertilizer valve 9 are all electrically connected to the controller. Specifically, the water and fertilizer valve 9, the mud pumping valve 7, the return valve 11 and the water and fertilizer valve 9 are all solenoid valves, which can realize automatic control of the entire system and reduce labor costs.

[0065] Optionally, in some embodiments, a stop valve is provided on the mud discharge pipe 5, and the stop valve is located on the side of the return pipe 12 away from the mud discharge pump 4. When the mud pumping pipe 2 is backflushed, in order to more concentratedly backflow the biogas slurry to backflush the mud pumping pipe 2, the stop valve is closed during backflushing. At this time, all the biogas slurry during backflushing will enter the mud pumping pipe to backflush it, thereby increasing the backflushing efficiency and effect.

[0066] A method of use, applied to the above-mentioned biogas residue direct return to farmland system,

[0067] Several mud pumping valves 7 are opened in turn, and each opening lasts for 1 hour;

[0068] When the pressure sensor 6 reaches the preset value, the fertilizer pumping pipe 8 is opened to reduce the solid content in the mixing pipe 3 to reduce the pipe pressure;

[0069] When the flow rate detected by the second flow meter 13 is lower than 20m³ / h, the mud pump 4 stops working, the return pipe 12 is opened, and the mud pump 4 reverses to extract the supernatant from the biogas tank 1 through the return pipe 12 to backwash the multiple mud extraction pipes 2 in turn;

[0070] After the backwash is completed, the mud pump 4 stops working, the reflux valve 11 is closed, the mud pump 4 rotates forward, and the second flow meter 13 continuously detects the flow rate;

[0071] If the flow rate increases, the mud pump 4 continues to work in the forward direction;

[0072] If the flow rate is lower than 20m³ / h, the system will shut down and sound an alarm.

[0073] In the above embodiment, a plurality of mud extraction pipes 2 are placed at the bottom of the biogas tank 1, and six mud extraction pipes 2 are used, which are named No. 1-6 pipes in sequence, and the sludge with a higher solid content is extracted through the mud pump 4. A plurality of mud extraction pipes 2 are provided with mud extraction solenoid valves, which are named No. 1-6 solenoid valves in sequence. A water and fertilizer extraction pipe 8 is placed in the biogas tank 1 and named No. 7 pipe, and the biogas with a lower solid content is extracted through the mixing pipe 3. The water and fertilizer extraction pipe 8 is provided with a water and fertilizer solenoid valve, which is named No. 7 solenoid valve. A return pipe 12 is connected to the outlet of the mud pump 4 and is named No. 8 pipe. The return pipe 12 is provided with a return solenoid valve, which is named No. 8 solenoid valve. The outlet of the mud pump 4 is provided with a flow meter and a pressure sensor 6.

[0074] During operation, valves 1-6 are opened alternately for one hour to ensure stable sludge discharge from the tank. Mud pump 4 is controlled by a frequency converter. When the pump outlet pressure is excessive, pressure sensor 6 sends a signal to the PLC, which in turn reduces the pump's speed to ensure constant sludge pressure. The control box has a preset upper limit for pipeline pressure (preset value), which can be overwritten using a mobile phone or the control panel.

[0075] When the pressure in the sludge discharge pipe 5 increases, in addition to reducing the rotation speed of the sludge discharge pump 4, valve No. 7 will be opened to reduce the solid content in the mixing pipe 3, thereby reducing the overall pressure of the pipe network.

[0076] When the flow rate of the sludge pump 4 is lower than 20m³ / h, the controller will stop the operation of the sludge pump 4 and open valve No. 8. The controller automatically switches the forward and reverse rotation of the sludge pump 4 (implemented by PLC control inverter). After switching, the sludge pump 4 is turned on, and the supernatant in the biogas tank 1 is extracted through the return pipe 12, and the pipes 1-6 are automatically back-flushed and back-flushed in turn. The back-flushing time is 1 minute. The back-flushing of the return pipe 12 can basically achieve the sludge extraction pipeline 2 to be unobstructed.

[0077] After backwashing, the forward and reverse rotation of the mud pump 4 is automatically switched, and the No. 8 valve is automatically closed. At this time, the mud pump 4 is running in the forward direction, and the electromagnetic flowmeter detects whether the flow at the outlet of the mud pump 4 increases. If the flow increases, the problem is solved, that is, the mud pumping pipe 2 is blocked. Normally, if the flow is still lower than 20m³ / h, the machine will stop and alarm, and the operating personnel will determine whether the problem is solved.

[0078] When pipe network pressure is high, flow velocity and flow rate are low. Opening pipe 7 can reduce the solid content of the sludge pumped by sludge pump 4. Testing shows that when the solid content is below 7%, the efficiency of pumping sludge and biogas liquid does not decrease.

[0079] In the above embodiment, the mud pump 4 adopts a rotor pump, which is a metering pump and can provide a higher suction head. After testing, the maximum negative pressure can reach -0.08MP, while the maximum negative pressure of other centrifugal pumps is -0.03MP. The solid content of the sludge extracted by the mud pump 4 is between 0-14%, and the solid content of the centrifugal pump is about 0-3.5%.

[0080] In the above embodiment, a field return network is installed at the bottom of the farmland, and a sludge pump 4 is connected to the field return network. The distal end of the sludge pump 4 returns biogas sludge and liquid biogas to the field through irrigation equipment. Specifically, a DN65 vertical rocker arm spray gun is used. Due to the high solid content of biogas residue and the presence of front-end livestock waste (such as ear tags, needles, and cable ties), other irrigation equipment tested failed to return the sludge smoothly and all experienced clogging. Examples include spray belts, vertical rocker arm nozzles, and PY-50 spray guns. Therefore, a DN65 vertical rocker arm spray gun was used as the field spraying equipment.

[0081] In the above embodiment, a large amount of sludge is retained in the pipe network after the return of the sludge to the field. The pipe network is generally about 3 kilometers long, so after the return of the sludge is completed, pipes 1-6 need to be closed and only pipe 7 opened to extract the sludge to flush the pipe network. The return of the sludge to the field continues until the pipe network is clean.

[0082] In the above embodiment, biogas sludge is sprayed and evenly distributed over the field before returning it to the field. After airing for one day to dry, the returned field is mechanically plowed at least 25 cm deep. High N and P content in biogas sludge can easily cause overnutrition and lodging of seasonal crops, hence the deep plowing requirement. While biogas sludge contains extremely high N and P content, only 40%-50% is fast-acting. The remainder is slow-release components that must be broken down by microorganisms into fast-acting NPs before they can be absorbed by plants. Deep plowing ensures long-lasting fertilizer effectiveness and prevents return-to-field accidents.

[0083] That is to say, the focus of the present invention is to place a number of mud extraction pipes 2 at the bottom of the biogas tank 1 to extract biogas with a higher solid content. When extracting, they are coordinated with the water and fertilizer extraction pipes 8, and under the action of the controller, the solid content of the biogas liquid entering the mixing pipe 3 and the mud pump 4 reaches a preset value. Specifically, the controller controls the opening of the mud extraction pipe 2 and the water and fertilizer extraction pipe 8, thereby controlling the solid content of the biogas liquid in the mixing pipe 3, realizing the rapid and continuous extraction and return of the biogas liquid in the biogas tank 1 to the field, reducing the content of biogas liquid at different positions in the biogas tank 1, cleaning a large amount of biogas residue, increasing the effective pool capacity of the pool, increasing the buffering time of biogas residue, and reasonably applying it to the land, which is beneficial to the weight loss and income increase of crops and realizing resource utilization.

[0084] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0085] The above is a detailed introduction to a system for directly returning biogas residue to fields and a method for using the system for directly returning biogas residue to fields provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the present invention.

Claims

1. A biogas residue direct return system for returning biogas residue to the field, used for extracting biogas liquid from a biogas tank (1) and returning it to the field, characterized in that: include: A plurality of mud extraction pipes (2), wherein the plurality of mud extraction pipes (2) are arranged at the bottom of the biogas tank (1); A mixing pipe (3), wherein the plurality of mud extraction pipes (2) are all connected to the mixing pipe (3); A mud discharge pump (4) and a mud discharge pipe (5), wherein the mud discharge pipe (5) is connected to the outlet of the mud discharge pump (4), and the mixing pipe (3) is connected to the inlet of the mud discharge pump (4); A water-fertilizer pumping pipe (8), the water-fertilizer pumping pipe (8) is arranged in the methane tank (1) and is connected to the mixing pipe (3); A controller is used to control the opening of the mud pumping pipeline (2) and the water and fertilizer pumping pipeline (8).

2. The biogas residue direct return system according to claim 1 is characterized in that: Also includes: A delivery pump (14), wherein the delivery pump (14) is connected to the pipe network, and the mud discharge pipeline (5) is connected to the outlet or inlet of the delivery pump (14).

3. The biogas residue direct return system according to claim 1, characterized in that: Also includes: A first flow meter (10) is installed on the water-pumping fertilizer pipeline (8) and is used to detect the flow of the water-pumping fertilizer pipeline (8). The first flow meter (10) is electrically connected to the controller.

4. The biogas residue direct return system according to claim 3 is characterized in that: Also includes: A second flow meter (13) is installed in the mud discharge pipe (5) and is used to detect the flow of the mud discharge pipe (5). The second flow meter (13) is electrically connected to the controller.

5. The biogas residue direct return to field system according to claim 4, characterized in that: Also includes: A pressure sensor (6) is installed in the mud discharge pipe (5) and is used to detect the pressure of the mud discharge pipe (5). The pressure sensor (6) is electrically connected to the controller.

6. The biogas residue direct return system according to any one of claims 1 to 5, characterized in that: Also includes: A return pipe (12), one end of the return pipe (12) is connected to the mud discharge pipe (5), and the other end of the return pipe (12) is connected to the biogas tank (1).

7. The biogas residue direct return system according to any one of claim 6, characterized in that: A plurality of the mud extraction pipes (2) are each provided with a mud extraction valve (7), a return valve (11) is provided on the return pipe (12), and a water and fertilizer valve (9) is provided on the water and fertilizer extraction pipe (8). The mud extraction valve (7), the return valve (11) and the water and fertilizer valve (9) are all electrically connected to a controller.

8. The biogas residue direct return to field system according to claim 7, characterized in that: The mud discharge pipe (5) is provided with a stop valve, and the stop valve is located on the side of the return pipe (12) away from the mud discharge pump (4).

9. A method of use, applied to the biogas residue direct return to field system according to any one of claims 1 to 8, characterized in that ； Several mud pumping valves (7) are opened in turn, and each opening lasts for 1 hour; When the pressure sensor (6) reaches a preset value, the fertilizer pumping pipe (8) is opened to reduce the solid content in the mixing pipe (3) to reduce the pipe pressure; When the flow rate detected by the second flow meter (13) is lower than 20 m³ / h, the mud pump (4) stops working, the return pipe (12) is opened, and the mud pump (4) reverses to extract the supernatant from the biogas tank (1) through the return pipe (12) to backwash the plurality of mud extraction pipes (2) in turn; After the backwash is completed, the mud pump (4) stops working, the reflux valve (11) is closed, the mud pump (4) rotates forward, and the second flow meter (13) continuously detects the flow rate; If the flow rate increases, the mud pump (4) continues to work in the forward direction; If the flow rate is lower than 20m³ / h, the system will shut down and sound an alarm.

10. The method of use according to claim 9, characterized in that: When the return to the field is completed, all the mud pumping valves (7) are closed, and the water and fertilizer valve (9) and the mud pump (4) are opened at the same time for a preset time.

Images