Pulse alternating ventilation composting apparatus and method

Abstract

The application discloses a pulse-alternating ventilation composting device, and belongs to the field of organic solid waste biological conversion. The device comprises a reactor main body and a gas reversing system. Two groups of vacuum electromagnetic valves are connected to the upper and lower air inlet and outlet of the reactor main body and are respectively connected to timing switches, so that pulse type down-in and up-out ventilation and up-in and down-out ventilation can be realized. An air blower, an air inlet valve, a digital gas flow meter, a gas pipeline heater are connected to the air inlet end, and a pipeline temperature and humidity recorder is connected to the air outlet end, so that gas flow and temperature regulation and control can be realized. Temperature sensors and oxygen concentration sensors are arranged on different heights of the reactor main body, so that online monitoring can be realized. A leachate discharge outlet is arranged below the filter screen, a reflux pump is connected, and a reflux pipe and a spray head are arranged, so that leachate reflux can be realized. Through cooperation of the above-mentioned structures, the device can realize pulse type up-down alternating ventilation of the composting body, effectively regulate and control the internal temperature, oxygen concentration and moisture content distribution of the composting body, and improve the composting efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of organic solid waste biological transformation, and particularly relates to a pulse alternating ventilation composting device and a composting method. Background Art

[0002] Aerobic composting is a green resource processing technology that can convert the initial macromolecular organic matter in organic solid waste, such as protein and fat, into complex and stable humus, and can use humus as a soil conditioner in agricultural production.

[0003] Existing static composting reactors often use one-way ventilation. A blower is typically installed at the bottom of the composting chamber to introduce air, and an exhaust port is located at the top of the reactor to discharge gases generated during the composting process. For example, Chinese patent publication CN113149740A discloses a composting and fermentation device comprising a composting device, wherein the fermentation chamber is a sealed chamber, the air outlet of the blower is located at the bottom of one longitudinal end of the fermentation chamber, and the exhaust port of the fermentation chamber is located at the top of the other longitudinal end of the fermentation chamber. Air circulation utilizes a "bottom-in, top-out" ventilation method to facilitate convection of air within the fermentation chamber. However, due to the constant ventilation direction, this method often leads to uneven heat transfer and moisture distribution. During the organic fertilizer fermentation process, relevant research has shown that the temperature difference between different layers of the composting chamber during the high-temperature period can exceed 10°C. This is mainly due to the tendency of heat and water vapor to migrate upward, especially during the high-temperature period. This makes the composting system environment unstable, restricts microbial metabolic activity, and reduces bioconversion efficiency, which is not conducive to comprehensive composting.

[0004] Chinese patent document CN214361058U discloses a laboratory composting device, which is provided with an air intake regulating device and enables a resettable air intake pipe to move up and down with the air intake regulating device. When the resettable air intake pipe is opposite to the air inlet, the resettable air intake pipe can automatically enter the air inlet and be sealed. This achieves rapid adjustment of the air intake position and is used to analyze the impact of ventilation at different heights of the compost on the composting effect. However, the device of the invention has poor stability. Since high-intensity water vapor is generated during the composting process, it is very easy to overflow from the connection between the air inlet and the resettable air intake pipe, generating unpleasant odors. In addition, it is difficult to ensure the stability of the internal air pressure of the device, and the air pressure tightness of the air intake regulating device is high. During operation, gas short-circuiting is likely to occur inside the pile body, making it difficult for the material to contact oxygen, thereby limiting its degradation rate.

[0005] In summary, in order to improve the composting fermentation effect of organic fertilizer, the ventilation strategy needs to be further optimized and a composting device that can instantly control the ventilation direction should be provided. Summary of the Invention

[0006] In order to solve the problem that composting devices in the prior art easily cause uneven decomposition of the pile, the present invention provides a pulse alternating ventilation composting device, which can realize pulse alternating ventilation of the compost reactor, and evenly distribute heat and moisture during the fermentation process; through the pulse alternating ventilation strategy, air flow rate and temperature regulation, the moisture content of the pile can be stabilized, the heat loss of the pile can be reduced, the high temperature period can be maintained, and the overall decomposition of the pile can be achieved.

[0007] The specific technical solutions adopted are as follows:

[0008] A pulse alternating ventilation composting device comprises a reactor body and a gas reversing system;

[0009] The reactor body is connected to the reactor cover to form a closed composting environment; the bottom of the side wall of the reactor body is provided with a lower air inlet and a lower air outlet, and the top of the side wall is provided with an upper air inlet and an upper air outlet;

[0010] The gas reversing system includes a blower, an air inlet valve, an air inlet vacuum solenoid valve, a timing switch, and an air outlet vacuum solenoid valve; the blower is used to provide air intake, and the air inlet valve is used to control air intake; the air inlet vacuum solenoid valve is connected to the upper air inlet and the lower air inlet through gas pipelines, respectively, and the upper air outlet and the lower air outlet are connected to the air outlet vacuum solenoid valve through gas pipelines, respectively; the timing switch is used to control the timing of opening and closing of the air inlet vacuum solenoid valve and the air outlet vacuum solenoid valve, thereby realizing pulsed bottom-in-top-out and top-in-bottom-out alternating ventilation;

[0011] A filter screen is also provided inside the reactor body. The leachate generated during the composting process is discharged through the leachate outlet at the bottom of the reactor body and flows back to the inside of the compost body through the spray head at the top of the reactor body.

[0012] The device of the present invention is provided with a vacuum solenoid valve at the air inlet end and a vacuum solenoid valve at the air outlet end, and utilizes the periodic reversing function of the solenoid valve to realize pulsed bottom-in-top-out and top-in-bottom-out alternating ventilation; and the device of the present invention is provided with a leachate reflux system. On the one hand, the organic matter in the leachate is degraded and converted by the composting reactor to achieve harmlessness, thereby reducing sewage discharge; on the other hand, the leachate reflux can replenish the moisture on the surface of the pile body, reduce the decrease in the moisture content of the upper layer of the water inside the pile body due to gravity, and thus accelerate the composting efficiency.

[0013] Preferably, when the vacuum solenoid valve at the air inlet end and the vacuum solenoid valve at the air outlet end are energized, the intake air enters the reactor body from the lower air inlet and is discharged from the upper air outlet; when the vacuum solenoid valve at the air inlet end and the vacuum solenoid valve at the air outlet end are de-energized, the intake air enters the reactor body from the upper air inlet and is discharged from the lower air outlet, realizing pulsed bottom-in-top-out and top-in-bottom-out alternating ventilation.

[0014] Preferably, the gas reversing system also includes a digital gas flow meter, a gas pipeline heater and a pipeline temperature and humidity recorder; the digital gas flow meter is connected to the air intake valve through a gas pipeline, and is used to automatically record the real-time flow and cumulative flow of the intake air; the gas pipeline heater is connected to the digital gas flow meter and the vacuum solenoid valve at the air intake end through a gas pipeline, and is used to regulate the temperature of the intake air; the pipeline temperature and humidity recorder is connected to the air outlet and the vacuum solenoid valve at the air outlet end through a gas pipeline, and is used to record the temperature and humidity of the outlet air.

[0015] Preferably, sampling ports, temperature sensors and oxygen concentration sensors at corresponding heights are respectively provided at different heights of the side wall of the reactor body; the temperature sensor is used to measure the temperature inside the pile at different heights in real time and record and store it in real time; the oxygen concentration sensor is used to measure the oxygen concentration inside the pile at different heights in real time and record and store it in real time.

[0016] Further preferably, at the positions where the stack is divided into four equal parts in the vertical direction, three groups of sampling ports, temperature sensors and oxygen concentration sensors at corresponding heights are respectively provided on the side walls of the reactor body; the diameter of the sampling ports is not less than 5 cm and is strictly sealed, which can facilitate sampling while achieving sealed and heat-insulated equipment.

[0017] Preferably, the reactor cover is connected to the reactor body via a flange and a silicone gasket to ensure the airtightness of the device.

[0018] Preferably, the outer wall of the reactor body is wrapped with a heat-insulating material with a thickness of not less than 5 cm, and the heat-insulating material is further preferably polystyrene foam.

[0019] Preferably, the mesh size of the filter is 2-5 mm. When the mesh size is smaller than 2 mm, the pile body will easily block the mesh size, restricting the air intake at the lower air inlet. When the mesh size is larger than 5 mm, the material produced during the degradation process will fall and block the leachate outlet.

[0020] Preferably, after the leachate is discharged from the leachate outlet, it flows back to the sprinkler head through the reflux pump and the reflux pipe.

[0021] The present invention also provides a composting method, comprising the following steps:

[0022] After mixing the organic solid waste with the expander, the compost was fermented using the pulse alternating ventilation composting device, with the air flow rate set at 0.1-1 L·min -1 kg -1 Dry the material; use the gas pipe heater to ensure the inlet air temperature is 20-35℃; set the ventilation mode to alternate between bottom-in and top-out and top-in and bottom-out, changing every 5-30 minutes; regularly open the leachate outlet to return the leachate and spray it into the pile; continue operation until the fermentation and composting is completed.

[0023] Under the above-mentioned preferred parameters, problems such as excessive heat dissipation of the pile, short high-temperature period, excessive moisture content of the pile, decreased oxygen mass transfer efficiency, and proliferation of anaerobic microorganisms leading to extended composting cycle and generation of odor can be avoided. The system effectively regulates the uniform distribution of temperature, oxygen concentration, and moisture content inside the pile, thereby improving composting efficiency.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The device of the present invention is provided with a gas reversing system, which can realize pulsed bottom-in-top-out and top-in-bottom-out alternating ventilation. Compared with the one-way ventilation method in the prior art, the heat and moisture distribution inside the pile is more uniform.

[0026] (2) The device of the present invention includes a reactor body and a gas reversing system. The upper and lower air inlets and outlets of the reactor body are connected to two groups of vacuum solenoid valves, which are respectively connected to time switches, so as to realize pulsed bottom-in and top-out and top-in and bottom-out alternating ventilation; the air inlet end is connected to a blower, an air inlet valve, a digital gas flow meter, and a gas pipeline heater, and the air outlet end is connected to a pipeline temperature and humidity recorder, so as to realize gas flow temperature regulation; temperature sensors and oxygen concentration sensors are respectively provided at different heights of the reactor body, so as to realize online monitoring; a flange is provided at the connection between the reactor body and the reactor cover plate, and the whole is covered with insulation material, so as to realize airtight insulation; a leachate discharge outlet is provided under the filter screen, which is connected to a reflux pump, a reflux pipe and a spray head, so as to realize leachate reflux. Through the cooperation of the above structures, the device of the present invention can realize pulsed top-bottom alternating ventilation of the pile body, effectively regulate the internal temperature, oxygen concentration and moisture content of the pile body, and improve the composting efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the pulse alternating ventilation composting device.

[0028] Figure 2 Schematic diagram of gas flow when the vacuum solenoid valve 5 at the air inlet end and the vacuum solenoid valve 21 at the air outlet end are energized and de-energized, wherein A represents the energized state and B represents the de-energized state.

[0029] Figure 3 This is a schematic diagram of the structure of the sampling port, temperature sensor and oxygen concentration sensor on the reactor body.

[0030] The figures are marked as follows: 1 blower, 2 air inlet valve, 3 digital gas flow meter, 4 pipeline temperature and humidity recorder, 5 air inlet end vacuum solenoid valve, 6 lower air inlet, 7 flange, 8 reactor cover, 9 silicone pad, 10 lower air outlet, 11 leachate outlet, 12 temperature sensor, 13 sampling port, 14 oxygen concentration sensor, 15 filter, 16 reactor body, 17 timer switch, 18 upper air inlet, 19 gas pipeline heater, 20 upper air outlet, 21 air outlet end vacuum solenoid valve, 22 spray head, 23 reflux pipe, 24 reflux pump. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the examples and accompanying drawings. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. The operating methods in the following examples where no specific conditions are specified are generally performed under conventional conditions or as recommended by the manufacturer.

[0032] Example 1 Pulse alternating ventilation composting device

[0033] like Figure 1 As shown, the pulse alternating ventilation composting device includes a reactor body 16 and a gas reversing system; specifically, it includes a blower 1, an air inlet valve 2, a digital gas flow meter 3, a gas pipeline heater 19, an air inlet end vacuum solenoid valve 5, a lower air inlet 6, a flange 7, a reactor cover 8, a silicone pad 9, a lower air outlet 10, a leachate outlet 11, a temperature sensor 12, a sampling port 13, an oxygen concentration sensor 14, a filter 15, a reactor body 16, a timer 17, an upper air inlet 18, a pipeline temperature and humidity recorder 4, an upper air outlet 20, a vacuum solenoid valve 21 at the air outlet end, a sprinkler head 22, a reflux pipe 23 and a reflux pump 24.

[0034] A reactor cover plate 8 is provided on the top of the reactor body 16, and the reactor cover plate 8 is connected to the reactor body 16 through a flange 7 and a silicone pad 9; a lower air inlet 6 and a lower air outlet 10 are provided at the bottom of the side wall of the reactor body 16, and an upper air inlet 18 and an upper air outlet 20 are provided at the top of the side wall; in the gas reversing system, the blower 1 is connected to the air inlet valve 2, the digital gas flow meter 3, the gas pipeline heater 19 and the air inlet end vacuum solenoid valve 5 in sequence through a gas pipeline, the air inlet end vacuum solenoid valve 5 is connected to the upper air inlet 18 and the lower air inlet 6 respectively through a gas pipeline, the upper air outlet 20 and the lower air outlet 10 are connected to the pipeline temperature and humidity recorder 4 and the air outlet end vacuum solenoid valve 21 respectively through a gas pipeline, and the timer switch 17 is used to control the timing opening and closing of the air inlet end vacuum solenoid valve 5 and the air outlet end vacuum solenoid valve 21, such as Figure 2As shown in A and B in the figure, when the vacuum solenoid valve 5 at the air inlet end and the vacuum solenoid valve 21 at the air outlet end are energized, the intake air enters the reactor body 16 from the lower air inlet 6 and is discharged from the upper air outlet 20; when the vacuum solenoid valve 5 at the air inlet end and the vacuum solenoid valve 21 at the air outlet end are de-energized, the intake air enters the reactor body 16 from the upper air inlet 18 and is discharged from the lower air outlet 10, realizing pulsed bottom-in-top-out and top-in-bottom-out alternating ventilation.

[0035] Three groups of sampling ports 13, temperature sensors 12 and oxygen concentration sensors 14 are respectively provided at different heights on the side wall of the reactor body 16. Figure 3 As shown, in each group at the same height, the sampling port 13, the temperature sensor 12 and the oxygen concentration sensor 14 are evenly distributed along the cross section of the reactor, and the angle between the sampling port 13 and the temperature sensor 12 and the center of the reactor cross section is equal to the angle between the sampling port 13 and the oxygen concentration sensor 14 and the center of the reactor cross section.

[0036] A filter screen 15 is provided inside the reactor body 16, and the mesh size of the filter screen is preferably 2-5 mm. A leachate collection port 11 is provided at the bottom. The leachate generated during the composting process is discharged through the leachate discharge port 11 at the bottom of the reactor body 16, and flows back to the inside of the compost body through the reflux pump 24, the reflux pipe 23 and the spray head 22; the outer wall of the reactor body 16 is wrapped with an insulation material, the thickness of the insulation material is not less than 5 cm, and the insulation material is preferably polystyrene foam.

[0037] Example 2: Method of using the pulse alternating ventilation composting device

[0038] Based on the pulse alternating ventilation composting device, organic solid waste such as kitchen waste and livestock and poultry manure are crushed and dehydrated, and 10% of an expander such as straw is added according to the wet-to-base mass ratio. After mixing, the reactor cover 8 is opened, the reactor is loaded into the reactor body 16, and the flange 7 is tightened to ensure the airtightness of the device.

[0039] Set the ventilation frequency of blower 1, and set it to start the gas pipe heater 19 when the room temperature is lower than 10℃, and the preheating temperature is set to 20℃. At the same time, set the timer switch 17 to "0.5h power on + 0.5h power off" mode, and connect the vacuum solenoid valve 5 at the air inlet end to the upper air inlet 18 and the lower air inlet 6. At the same time, the upper air outlet 20 and the lower air outlet 10 are connected to the pipeline temperature and humidity recorder 4 and the vacuum solenoid valve 21 at the air outlet end in sequence. The connection method must ensure that when the two sets of vacuum solenoid valves are energized, the gas enters from the lower air inlet 6 and exits from the upper air outlet 20. When the power is off, the gas enters from the upper air inlet 18 on the left and exits from the lower air outlet 10 on the right.

[0040] At the positions where the pile body is divided into four equal parts in the vertical direction, three groups of sampling ports 13, temperature sensors 12 and oxygen concentration sensors 14 are respectively provided on the side walls of the reactor body 16 at corresponding heights. The diameter of the sampling port 13 is 5 cm. Samples are taken from the sampling port every 3 days, and real-time monitoring and data storage are performed using the temperature sensor 12 and the oxygen concentration sensor 14. At the same time, the leachate discharge port is opened regularly, and the reflux pump is started to return the leachate to the pile body. After the composting is completed, the flange 7 and the reactor cover 8 are opened for discharge.

[0041] Example 3 Composting method

[0042] Three composting devices were operated synchronously, named A1, A2 and A3, respectively. Except for the ventilation device, the other designs of A1, A2 and A3 were the same. A1 was the pulse alternating ventilation composting device in the present invention, A2 was the traditional upward unidirectional ventilation (the only air inlet was set at the bottom, and the only air outlet was set at the top), and A3 was the traditional downward unidirectional ventilation (the only air inlet was set at the top, and the only air outlet was set at the bottom). The reactor body was barrel-type with a diameter of 360 mm, a height of 800 mm, an effective volume of 60 L, a filter screen 10 mm from the bottom, and an initial pile material of 33 kg of kitchen waste and 3.3 kg of wheat straw (the weight of the dry material was about 12.7 kg). The ventilation frequency was 1.8 L min -1 , use the gas pipe heater to ensure that the inlet air temperature is 25℃, set the ventilation mode to alternate between bottom-in and top-out and top-in and bottom-out, change every 30 minutes, run for 37 days, open the leachate outlet every day to return the leachate and spray it into the pile; continue to run until the fermentation and composting is completed.

[0043] Results showed that Group A1 extended the high-temperature period by 21 days, a 35% increase compared to the other two groups. The average oxygen concentration in Group A1 was lower than in the other two groups. The moisture content of the piles in Group A1 remained around 60%, while that in Group A2 gradually increased to around 80%, and in Group A3 gradually decreased to 30%. Furthermore, according to actual measurements, the seed germination rate in Group A1 reached 84.49%, an increase of 48.21% and 20.07% compared to the other two groups.

[0044] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A composting method, characterized in that: The method comprises the following steps: mixing organic solid waste with a swelling agent and then fermenting and composting the mixture using a pulse alternating ventilation composting device, wherein the pulse alternating ventilation composting device comprises a reactor body (16) and a gas reversing system; The reactor body (16) is connected to the reactor cover plate (8) to form a closed composting environment; the bottom of the side wall of the reactor body (16) is provided with a lower air inlet (6) and a lower air outlet (10), and the top of the side wall is provided with an upper air inlet (18) and an upper air outlet (20); The gas reversing system comprises a blower (1), an air inlet valve (2), an air inlet end vacuum solenoid valve (5), a timing switch (17) and an air outlet end vacuum solenoid valve (21); the blower (1) is used to provide air inlet, and the air inlet valve (2) is used to control air inlet; the air inlet end vacuum solenoid valve (5) is connected to the upper air inlet (18) and the lower air inlet (6) through gas pipelines, respectively, and the upper air outlet (20) and the lower air outlet (10) are connected to the air outlet end vacuum solenoid valve (21) through gas pipelines; the timing switch (17) is used to control the timing opening and closing of the air inlet end vacuum solenoid valve (5) and the air outlet end vacuum solenoid valve (21), so as to realize pulsed bottom-in-top-out and top-in-bottom-out alternating ventilation; The reactor body (16) is further provided with a filter screen (15) inside, and the leachate generated during the composting process is discharged through the leachate outlet (11) at the bottom of the reactor body (16) and flows back into the compost body through the spray head (22) at the top of the reactor body (16); Set the air flow rate to 0.1-1 L·min -1 kg -1 Dry materials; use a gas pipeline heater to ensure that the intake air temperature is 20-35°C; set the ventilation mode to alternate between bottom-in and top-out and top-in and bottom-out, when the vacuum solenoid valve (5) at the air inlet end and the vacuum solenoid valve (21) at the air outlet end are energized, the intake air enters the reactor body (16) from the lower air inlet (6) and is discharged from the upper air outlet (20); when the vacuum solenoid valve (5) at the air inlet end and the vacuum solenoid valve (21) at the air outlet end are de-energized, the intake air enters the reactor body (16) from the upper air inlet (18) and is discharged from the lower air outlet (10), realizing pulsed bottom-in and top-out and top-in and bottom-out ventilation alternately, and changing every 5-30 minutes; regularly open the leachate discharge port to reflux the leachate and spray it into the pile body; continue to operate until the fermentation and composting is completed.

2. The composting method according to claim 1, wherein The gas reversing system further comprises a digital gas flow meter (3), a gas pipeline heater (19) and a pipeline temperature and humidity recorder (4); the digital gas flow meter (3) is connected to the air inlet valve (2) via a gas pipeline; the gas pipeline heater (19) is connected to the digital gas flow meter (3) and the air inlet end vacuum solenoid valve (5) via a gas pipeline; the pipeline temperature and humidity recorder (4) is connected to the air outlet and the air outlet end vacuum solenoid valve (21) via a gas pipeline.

3. The composting method according to claim 1, wherein: Sampling ports (13), temperature sensors (12) and oxygen concentration sensors (14) at corresponding heights are respectively arranged at different heights on the side wall of the reactor body (16).

4. The composting method according to claim 1, wherein At the positions where the stack is divided into four equal parts in the vertical direction, three groups of sampling ports (13), temperature sensors (12) and oxygen concentration sensors (14) at corresponding heights are respectively provided on the side walls of the reactor body (16).

5. The composting method according to claim 1, wherein: The reactor cover plate (8) is connected to the reactor body (16) via a flange (7) and a silicone gasket (9).

6. The composting method according to claim 1, wherein: The outer wall of the reactor body (16) is wrapped with a heat-insulating material with a thickness of not less than 5 cm, and the heat-insulating material is polystyrene foam.

7. The composting method according to claim 1, wherein: The mesh size in the filter (15) is 2-5 mm.

8. The composting method according to claim 1, wherein: After being discharged from the leachate outlet (11), the leachate is returned to the spray head (22) through the reflux pump (24) and the reflux pipe (23).

Images