Dry-type high-pressure anaerobic fermentation system and method for agricultural wastes

Abstract

The invention discloses a dry-type high-pressure anaerobic fermentation system and method for agricultural waste, and belongs to the technical field of biogas fermention.The dry-type high-pressure anaerobic fermentation system comprises a mixing pool, a feeding tank and an anaerobic fermentation reactor, and the feeding tank is connected with a hydrolysis pool feeding pipeline and an acid production pool feeding pipeline; the anaerobic fermentation reactor comprises a hydrolysis tank, an acid production tank and a methane production tank which are separated by a reactor outer wall, a first separation wall and a second separation wall which are arranged in a concentric circle, and a biogas collection area formed by a separation top plate and a reactor dome is arranged at the top end of the reactor outer wall; an overflow channel is formed at the top end of the first separating wall; a plurality of separating wall supporting columns are circumferentially and uniformly distributed at the bottom of the second separating wall; a leachate tank is correspondingly arranged at the bottom end of the methanogenesis tank, and a plurality of biogas slurry lifting pipes are arranged in the methanogenesis tank; a fermentation waste discharge pipeline is arranged on the side wall of the second separation wall, a biogas discharge pipe is arranged on the dome of the reactor, and the fermentation system is stable in operation, small in consumption of circulating inoculum and high in volume gas production rate.

Description

Technical Field

[0001] The invention relates to the technical field of biogas fermentation, and in particular to a dry high-pressure anaerobic fermentation system and method for agricultural waste. Background Art

[0002] Industrialized treatment of organic waste such as livestock and poultry manure and crop waste and the development of biogas can effectively solve my country's agricultural and pollution problems, while helping to achieve the "dual carbon" goal. Compared with other biogas production technologies, dry high-temperature anaerobic fermentation technology has the advantages of low energy consumption for heating raw materials, high gas production efficiency, and less biogas slurry, making it a research hotspot for anaerobic fermentation of agricultural waste to produce biogas. However, dry high-temperature anaerobic fermentation technology is complex and its development is relatively lagging. At present, there are still shortcomings such as low organic load of anaerobic digestion and poor economic benefits, making it difficult to achieve industrial application.

[0003] At present, the dry high-temperature anaerobic fermentation of agricultural waste to produce biogas in China generally adopts a horizontal push flow system, which has the following shortcomings: (1) The substrate concentration is too high, making mass transfer and heat transfer difficult. VFAs are easily accumulated locally during the acidification stage to form acid inhibition, causing anaerobic fermentation to become unstable or even stop; (2) In order to ensure the stability of the fermentation process, a large amount of inoculum is required to ensure the colonization rate of fermentation bacteria and agricultural waste, resulting in a waste of equipment volume and power; (3) The horizontal push flow reactor occupies a large area, and the equipment is mainly purchased from abroad, with high investment costs; (4) The feeding unit uses a plunger feeder or a screw conveyor to feed. (5) In order to make the material move forward, a side multi-axis mechanical stirring or axial flow mixing stirring is used, which causes the material to be mixed, resulting in an uneven distribution of the material residence time in the reactor and a low volumetric gas production rate; (6) Although multi-axis stirring can make the fermentation reactor large-scale, the stirring energy consumption is high, resulting in poor economic benefits of gas production; (7) Axial flow stirring is restricted by the fact that the length of the stirring shaft cannot be extended indefinitely, and the reactor is difficult to be large-scale and cannot obtain scale benefits; (8) The vacuum discharge system is complex and cannot discharge materials continuously. Summary of the invention

[0004] Technical problem to be solved: In view of the shortcomings of the horizontal push-flow dry anaerobic fermentation system, the present invention provides a dry high-pressure anaerobic fermentation system and method for agricultural waste, which solves the problems of unstable fermentation process under high load, excessive amount of circulating inoculum, low volumetric gas production rate, high energy consumption and operation and maintenance costs, and difficulty in large-scale and scale-up of the reactor, reduces the production cost of agricultural waste biogas production, and realizes the industrialization and large-scale production of agricultural waste.

[0005] Technical solution: The dry high-pressure anaerobic fermentation system for agricultural waste described in the present invention comprises: A mixing tank, which adjusts the moisture and concentrations of bicarbonate, hydrogen phosphate, and nitrogen in the agricultural waste to provide nutrients for the microorganisms in the fermentation process; A feed tank, wherein the feed tank is connected to the mixing tank through a feed pipeline, and the feed outlet of the feed tank is respectively connected to the feed pipeline of the hydrolysis tank and the feed pipeline of the acid generation tank; a positive and negative pressure control mechanism is provided in conjunction with the feed tank, and the positive and negative pressure control mechanism adjusts the feed tank to be in a positive pressure state or a negative pressure state; the feed pipeline, the feed pipeline of the hydrolysis tank and the feed pipeline of the acid generation tank are all connected to control valves; An anaerobic fermentation reactor, the anaerobic fermentation reactor comprises an outer wall of the reactor, a first isolation wall and a second isolation wall arranged in concentric circles from the outside to the inside, a hydrolysis tank is formed between the outer wall of the reactor and the first isolation wall, an acid production tank is formed between the first isolation wall and the second isolation wall, a methane production tank is formed in the second isolation wall, and a feed pipeline for the hydrolysis tank and a feed pipeline for the acid production tank extend from the upper end and are inserted into the bottom of the hydrolysis tank and the acid production tank, respectively; wherein, A reactor dome is arranged at the top of the outer wall of the reactor, and an isolation top plate is arranged between the reactor dome and the outer wall of the reactor, and a biogas collection area is formed between the isolation top plate and the reactor dome; the top of the first isolation wall is lower than the isolation top plate to form an overflow channel, the top of the second isolation wall is sealed and connected to the isolation top plate, and a plurality of isolation wall support columns are evenly distributed in the circumferential direction of the bottom of the second isolation wall, and the height of the isolation wall support columns is not less than 500m; a connecting channel connecting the acid production pool and the methane production pool is formed between adjacent isolation wall support columns; an overflow hole connecting the acid production pool is arranged on the side wall at the top of the second isolation wall, and the overflow hole is opened at a position at least 500mm higher than the height of the top of the first isolation wall; A leachate pool is provided at the bottom of the methane production pool, and a plurality of biogas liquid lifting pipes connecting the leachate pool and the biogas collection area are provided in the methane production pool. The diameter of the biogas liquid lifting pipe is less than 150 mm, and the number shall not be less than 3, and the biogas liquid lifting pipes are arranged in concentric circles in the methane production pool; the isolation top plate is located on the periphery of the biogas liquid lifting pipe and is respectively provided with a plurality of liquid distribution holes connecting the biogas collection area with the hydrolysis pool and the acid production pool. The leachate stored in the leachate pool enters the biogas collection area through the biogas liquid lifting pipe and flows into the hydrolysis pool and the acid production pool through the liquid distribution holes respectively; The side wall of the second isolation wall is provided with a fermentation waste discharge pipeline connected to the methane production pool below the overflow hole, and the fermentation waste discharge pipeline is connected to a waste discharge control valve; The reactor dome is provided with a biogas discharge pipe, and a biogas control valve is connected to the biogas discharge pipe.

[0006] Preferably, the outer wall of the reactor and the hydrolysis tank are provided with heat input pipelines and temperature sensors respectively, the heat input pipeline is connected to a heat control valve, the temperature sensor is interlocked with the heat control valve and the opening of the heat control valve is controlled by the temperature sensor.

[0007] Preferably, the bottom plate of the anaerobic fermentation reactor and the leachate pool are provided with permeation holes correspondingly, and the excess volatile organic acid produced by the acid production pool enters the leachate pool through the permeation holes under the action of gravity and pressure for storage; The leachate pool is connected to the upper end of the hydrolysis tank through a leachate drainage pipeline and a liquid drainage pump connected thereto. The outlet installation height of the leachate drainage pipeline is at least 500mm higher than the first isolation wall. An organic acid monitoring sensor is connected to the leachate drainage pipeline.

[0008] Preferably, the reactor dome is provided with a biogas pressure monitoring sensor connected to the biogas collection area, and the biogas pressure monitoring sensor is interlocked with the biogas control valve to control the opening of the biogas control valve.

[0009] Preferably, the bottom end of the hydrolysis tank feed pipeline is less than 2 times the diameter of the hydrolysis tank feed pipeline from the bottom of the hydrolysis tank; the bottom end of the acid generation tank feed pipeline is 3 / 4 of the height of the first isolation wall from the bottom of the acid generation tank.

[0010] The present invention also discloses a dry high-pressure anaerobic fermentation method for agricultural waste, the fermentation method comprising the following steps: Step 1: Adjust the moisture, bicarbonate, hydrogen phosphate and nitrogen of the agricultural waste to the required concentrations through the mixing tank, close the hydrolysis feed control valve and the acid generation feed control valve, open the feed control valve, and adjust the positive and negative pressure control mechanism to form a negative pressure in the feed tank. Under the action of negative pressure, the reaction materials enter the feed tank through the feed pipeline; Step 2: close the feed control valve and the acid-generating feed control valve, open the hydrolysis feed control valve, and form a positive pressure in the feed tank by adjusting the positive and negative pressure control mechanism. Under the positive pressure, the reaction material enters the bottom of the hydrolysis tank through the hydrolysis tank feed pipeline for hydrolysis reaction; then, under the positive pressure and gravity, the liquid level of the reaction material gradually rises to exceed the height of the first isolation wall and overflows through the overflow channel into the acid-generating tank for acidification reaction; Step 3: close the feed control valve and the hydrolysis feed control valve, open the acid-generating feed control valve, and adjust the positive and negative pressure control mechanism to form a negative pressure in the feed tank. Under the negative pressure, part of the non-acid-generating material in the acid-generating tank enters the feed tank; then close the hydrolysis feed control valve and the acid-generating feed control valve, open the feed control valve, and adjust the positive and negative pressure control mechanism to form a positive pressure in the feed tank. Under the positive pressure, the non-acid-generating material enters the mixing tank and mixes with the agricultural waste; Step 4: Repeat steps 1 to 3 to allow the fermentation material to fully react in the hydrolysis tank and the acid production tank of the anaerobic fermentation reactor; Step 5: The fermented materials in the acid-producing pool enter the methane-producing pool through the connecting channel between the support columns of the isolation wall under the action of their own weight, completing the methane-producing process; the excess volatile organic acids and water in the methane-producing pool enter the leachate pool under the action of gravity; Step 6: After the methanogenesis process is completed, the waste discharge control valve is opened, and the fermentation waste is discharged from the methanogenesis pool through the fermentation waste discharge pipeline; the fermentation process of the anaerobic fermentation reactor is a continuous reaction, and the waste discharge control valve is normally open when the fermentation is running stably; at the same time, by adjusting the opening of the waste discharge control valve, the fermentation waste is kept full of the inlet end of the fermentation waste discharge pipeline to prevent air from entering the methanogenesis pool; Step 7: After the methanogenesis process is completed, the biogas control valve on the biogas discharge pipe is opened, and the biogas is discharged from the anaerobic fermentation reactor through the biogas discharge pipe; the fermentation process of the anaerobic fermentation reactor is a continuous reaction, and the biogas control valve is normally open when the fermentation is running stably; the opening of the biogas control valve is adjusted according to the pressure monitored by the biogas pressure monitoring sensor to maintain the pressure in the biogas collection area stable and ensure the smooth progress of the fermentation reaction process.

[0011] Preferably, in step 5, part of the leachate in the leachate pool enters the biogas collection area through the biogas lifting pipe, and then flows back to the acid production pool and the hydrolysis pool through the liquid distribution holes arranged on the isolation top plate; part of the leachate and particulate matter are extracted through the leachate drainage pipeline, and then pumped into the hydrolysis pool by a liquid drainage pump to adjust the pH of the acid production pool and the bacterial flora of the hydrolysis pool.

[0012] Preferably, in step 2, the opening of the heat control valve is adjusted according to the temperature data monitored by the temperature sensor; when the temperature of the hydrolysis tank exceeds the threshold, the opening of the heat control valve is reduced to reduce the heat input; when the temperature of the hydrolysis tank is lower than the threshold, the opening of the heat control valve is increased to increase the heat input; and the hydrolysis temperature of the hydrolysis tank is maintained within a preset temperature range by adjusting the heat input.

[0013] Preferably, during steps 1 to 2, the opening of the feed control valve is adjusted according to the monitoring data of the organic acid monitoring sensor; when the volatile organic acid value is high, the opening of the feed control valve is reduced to reduce the feed amount; when the volatile organic acid value is low, the opening of the feed control valve is increased to increase the feed amount; the reaction process is automatically adjusted to ensure stable and continuous operation of the reaction process.

[0014] Preferably, in step 7, the opening of the biogas control valve is adjusted according to the monitoring data of the biogas pressure monitoring sensor; when the biogas pressure value is higher than the threshold value, the opening of the biogas control valve is increased to accelerate the discharge of biogas from the biogas collection area; when the biogas pressure value is lower than the threshold value, the opening of the biogas control valve is reduced to reduce the discharge of biogas from the biogas collection area; and the pressure in the biogas collection area is maintained stable.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The fermentation system of the present invention has stable fermentation process operation under high load, small consumption of circulating inoculum, high volumetric gas production rate of anaerobic fermentation reactor, significantly reduces comprehensive energy consumption and operation and maintenance costs, reduces production costs of agricultural waste biogas, and realizes industrialization and large-scale production of agricultural waste.

[0016] 2. The hydrolysis tank of the anaerobic fermentation reactor can improve the colonization of hydrolytic bacteria, regulate the hydrolytic bacteria, and increase the hydrolysis temperature, thereby increasing the hydrolysis rate of agricultural waste, breaking the restriction of the hydrolysis rate limit, preliminarily completing the colonization of anaerobic fermentation bacteria in the hydrolysis stage, and increasing the contact area and contact probability between the hydrolysis anaerobic fermentation bacteria and the reaction materials; the excess volatile organic acids and water in the methanogen pool enter the leachate pool through the infiltration holes, and the excess volatile organic acids produced by the acidogen pool can be separated or utilized in time to reduce or eliminate the acid inhibition of the methanogen process, and avoid excessive acid inhibition of the methanogen pool caused by the acidogen stage of agricultural waste; thereby improving the methane production capacity of the reactor.

[0017] 3. The combination of the mixing tank and the feed tank can not only realize the material preparation and autonomous feeding of agricultural waste, but also return some of the non-acid-producing materials in the acid-producing tank to the mixing tank to mix with the agricultural waste. The beneficial hydrolytic biological flora is brought in by the reflux of undigested materials to enhance the hydrolysis rate.

[0018] The present invention also has other beneficial effects which are described in the embodiments of the specification and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A structural cross-sectional view of a fermentation system according to an embodiment of the present invention along its height direction; Figure 2 for Figure 1 AA structural section view of the medium fermentation system; Figure 3 for Figure 1 BB structural cross-section view of the mid-fermentation system; Figure 4 for Figure 1 CC structural cross-section view of the fermentation system.

[0020] Figure numerals: 1, mixing tank; 2, feed pipeline; 3, feed control valve; 4, feed tank; 5, positive and negative pressure control mechanism; 6, hydrolysis tank feed pipeline; 7, hydrolysis feed control valve; 8, acid production tank feed pipeline; 9, acid production feed control valve; 10, anaerobic fermentation reactor; 110, reactor outer wall; 120, reactor dome; 130, first isolation wall; 140, second isolation wall; 150, isolation wall support column; 160, biogas slurry lifting pipe; 170, hydrolysis tank; 180, acid production tank; 190, methane production tank; 1100, isolation top plate; 1101, hydrolysis inlet Material pipe hole; 1102, acid-generating feed pipe hole; 1103, biogas slurry lifting pipe hole; 1104, liquid distribution hole; 1110, biogas collection area; 1120, leachate tank; 1130, overflow channel; 1140, connecting channel; 1150, overflow hole; 11, biogas pressure monitoring sensor; 12, biogas discharge pipe; 13, biogas control valve; 14, leachate drainage pipeline; 15, liquid drainage pump; 16, heat input pipeline; 17, heat control valve; 18, temperature sensor; 19, fermentation waste discharge pipeline; 20, waste discharge control valve; 21, organic acid monitoring sensor. DETAILED DESCRIPTION

[0021] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the following will be combined with the attached Figures 1 to 4 The technical solutions of the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0022] Example 1: Figure 1 As shown, the present invention discloses a dry high-pressure anaerobic fermentation system for agricultural waste. The fermentation system includes a mixing tank 1, a feed tank 4 and an anaerobic fermentation reactor 10.

[0023] The mixing tank 1 adjusts the moisture content and the concentrations of bicarbonate, hydrogen phosphate and nitrogen in the agricultural waste, and provides nutrients that are easily utilized by microorganisms in the fermentation process.

[0024] The feed tank 4 is connected to the mixing tank 1 through the feed pipeline 2, the feed control valve 3 is connected to the feed pipeline 2, the outlet of the feed tank 4 is connected to the hydrolysis tank feed pipeline 6 and the acid generation tank feed pipeline 8 respectively, and the hydrolysis feed control valve 7 and the acid generation feed control valve 9 are connected to the hydrolysis tank feed pipeline 6 and the acid generation tank feed pipeline 8. A positive and negative pressure control mechanism 5 is provided in conjunction with the feed tank 4, and the positive and negative pressure control mechanism 5 adjusts the positive pressure state or negative pressure state in the feed tank 4, thereby adjusting the material conveying state of the fermentation process; the positive and negative pressure control mechanism 5 can use existing technology to realize its pressure regulation function, for example, a vacuum pump or an air compressor is used to realize the pressure regulation function in the feed tank 4.

[0025] like Figure 1 As shown, the anaerobic fermentation reactor 10 includes a reactor outer wall 110, a first isolation wall 130, and a second isolation wall 140 arranged in concentric circles from the outside to the inside, a hydrolysis tank 170 is formed between the reactor outer wall 110 and the first isolation wall 130, an acid production tank 180 is formed between the first isolation wall 130 and the second isolation wall 140, and a methane production tank 190 is formed in the second isolation wall 140. A reactor dome 120 is arranged at the top of the reactor outer wall 110, an isolation top plate 1100 is arranged between the reactor dome 120 and the reactor outer wall 110, and a biogas collection area 1110 is formed between the isolation top plate 1100 and the reactor dome 120. The top of the first isolation wall 130 is lower than the isolation top plate 1100 to form an overflow channel 1130, and the hydrolysis tank 170 is connected to the acid production tank 180 through the overflow channel 1130, and the hydrolyzate produced by the hydrolysis tank 170 enters the acid production tank 180 through the overflow channel 1130 for acidification reaction. The top of the second isolation wall 140 is sealed and connected to the isolation top plate 1100. A plurality of isolation wall support columns 150 are evenly distributed in the circumferential direction at the bottom of the second isolation wall 140. The height of the isolation wall support columns 150 is not less than 500m, so that the material in the acid-generating pool 180 can enter the methane-generating pool 190. A connecting channel 1140 is formed between adjacent isolation wall support columns 150 to connect the acid-generating pool 180 and the methane-generating pool 190. The reaction material in the acid-generating pool 180 can enter the methane-generating pool 190 through the connecting channel 1140 to produce methane. An overflow hole 1150 is provided on the side wall at the top of the second isolation wall 140 to connect the acid-generating pool 180. The overflow hole 1150 is opened at a position at least 500mm higher than the top of the first isolation wall 130. When the height of the material in the methane-generating pool 190 is too high, it enters the acid-generating pool 180 through the overflow hole 1150 to avoid squeezing the isolation top plate 1100 to form a blockage. Each reaction stage of the anaerobic fermentation reactor 10 of the present invention is not affected by the factors of the previous and subsequent system stages, and the working environment of each stage can be accurately controlled so that the functional bacteria in each stage can exert their maximum advantages and achieve a higher stable operating load, thereby improving the fermentation efficiency of agricultural waste and the biogas yield.

[0026] like Figure 2As shown, a leachate tank 1120 is correspondingly arranged at the bottom of the methane production tank 190, and a plurality of biogas slurry lifting pipes 160 connecting the leachate tank 1120 and the biogas collection area 1110 are arranged in the methane production tank 190. The diameter of the biogas slurry lifting pipe 160 is less than 150 mm, and the number shall not be less than 3, and they are arranged in concentric circles in the methane production tank 190; the isolation top plate 1100 is provided with a biogas slurry lifting pipe hole 1103 corresponding to the biogas slurry lifting pipe 160. On the isolation top plate 1100, a plurality of liquid distribution holes 1104 are respectively opened at the periphery of the biogas slurry lifting pipe 160, connecting the biogas collection area 1110 with the hydrolysis tank 170 and the acid production tank 180. The liquid distribution holes 1104 include two circles distributed in an annular shape, which are respectively arranged corresponding to the hydrolysis tank 170 and the acid production tank 180. The leachate stored in the leachate tank 1120 can enter the biogas collection area 1110 through the biogas slurry lifting pipe 160 and flow into the hydrolysis tank 170 and the acid production tank 180 through the liquid distribution holes 1104.

[0027] like Figure 1 and Figure 3 As shown, the side wall of the second isolation wall 140 is provided with a fermentation waste discharge pipeline 19 connected to the methanogen 190 below the overflow hole 1150, and the fermentation waste discharge pipeline 19 is connected to the waste discharge control valve 20, and the discharge operation of the fermentation waste in the methanogen 190 can be achieved by controlling the discharge control valve. The reactor dome 120 is provided with a biogas discharge pipe 12, and the biogas discharge pipe 12 is connected to the biogas control valve 13, and the biogas pressure in the biogas collection area 1110 is adjusted by controlling the opening of the biogas control valve 13.

[0028] like Figure 2 As shown, a hydrolysis feed pipe hole 1101 and an acid-generating feed pipe hole 1102 are respectively provided on the partition wall top plate corresponding to the hydrolysis tank 170 and the acid-generating tank 180, and the hydrolysis tank feed pipe line 6 and the acid-generating tank feed pipe line 8 extend from the upper end through the hydrolysis feed pipe hole 1101 and the acid-generating tank feed pipe hole 1102 and are inserted into the bottom of the hydrolysis tank 170 and the acid-generating tank 180. The distance between the bottom end of the hydrolysis tank feed pipe line 6 and the bottom of the hydrolysis tank 170 is less than 2 times the diameter of the hydrolysis tank feed pipe line 6 to avoid residual or direct flow of materials in the hydrolysis tank 170. The distance between the bottom end of the acid-generating tank feed pipe line 8 and the bottom of the acid-generating tank 180 is 3 / 4 of the height of the first partition wall 130, which ensures the acid-generating efficiency and the balance of the reflux used to adjust the hydrolysis and fermentation flora.

[0029] like Figure 1As shown, the reactor outer wall 110 and the hydrolysis tank 170 are provided with a heat input pipeline 16 and a temperature sensor 18 correspondingly. The heat input pipeline 16 is connected to a heat control valve 17. The temperature sensor 18 is interlocked with the heat control valve 17 for control. The opening of the heat control valve 17 is controlled by the temperature sensor 18 to control the temperature of the hydrolysis tank 170 within the range of 60-85°C, so that the hydrolysis temperature is slightly higher than the working temperature of the acid production tank 180 and the methane production tank 190, thereby increasing the hydrolysis rate of agricultural waste; excess heat enters the environment through the bottom of the reactor outer wall 110 to avoid the adverse effects of high hydrolysis temperature on subsequent fermentation processes.

[0030] like Figure 1 As shown, the bottom plate of the anaerobic fermentation reactor 10 and the leachate pool 1120 are provided with permeation holes correspondingly, and the excess volatile organic acid produced by the acid production pool 180 enters the leachate pool 1120 through the permeation holes under the action of gravity and pressure for storage. The leachate pool 1120 is connected to the upper end of the hydrolysis pool 170 through the leachate drainage pipeline 14 and the liquid drainage pump 15 connected thereto. The outlet installation height of the leachate drainage pipeline 14 is at least 500 mm higher than the first isolation wall 130, which can prevent the fermentation materials from clogging the filtrate drainage pipe. Under the action of gravity and pressure, the excess volatile organic acids and water in the methanogenizing pool 190 enter the leachate pool 1120 through the permeation holes, and the excess volatile organic acids produced by the acidogenizing pool 180 can be separated or utilized in time to reduce or eliminate the acid inhibition of the methanogenizing process and avoid excessive acid production of agricultural waste in the methanogenizing pool 190. The leachate and particulate matter in the leachate pool are extracted by the liquid drainage pump 15 to prevent the accumulation of particulate matter. At the same time, the volatile organic acids in the acidogenizing stage are discharged into the hydrolysis pool 170 to reduce the pH of the hydrolysis pool 170, optimize the hydrolysis environment of the hydrolysis pool 170, and increase the hydrolysis rate. An organic acid monitoring sensor 21 is connected to the leachate discharge pipeline 14. The organic acid monitoring sensor 21 detects the acidity of the leachate, quickly determines the type and concentration of volatile organic acids in the leachate, and indirectly measures the fermentation status of the acid production stage online, effectively warning of dry anaerobic fermentation instability and enhancing process reliability.

[0031] like Figure 1 As shown, the reactor dome 120 is provided with a biogas pressure monitoring sensor 11 connected to the biogas collection area 1110. The biogas pressure monitoring sensor 11 is interlocked with the biogas control valve 13 and controls the opening of the biogas control valve 13 to keep the pressure in the biogas collection area 1110 stable within a certain range, so that the anaerobic fermentation process can run stably.

[0032] The fermentation system of the present invention has stable fermentation process operation under high load conditions, low consumption of circulating inoculum, and high volumetric gas production rate of the anaerobic fermentation reactor 10, which significantly reduces the comprehensive energy consumption and operation and maintenance costs, reduces the production cost of agricultural waste biogas production, and realizes the industrialization and large-scale production of agricultural waste.

[0033] Example 2: The present invention also discloses a dry high-pressure anaerobic fermentation method for agricultural waste, the fermentation method comprising the following steps: (i) The water content, bicarbonate, hydrogen phosphate and nitrogen of the agricultural waste are adjusted to the required concentrations through the mixing tank 1, the hydrolysis feed control valve 7 and the acid production feed control valve 9 are closed, the feed control valve 3 is opened, and a negative pressure is formed in the feed tank 4 by adjusting the positive and negative pressure control mechanism 5. Under the action of the negative pressure, the reaction material enters the feed tank 4 through the feed pipeline 2 to complete the material preparation of the agricultural waste. The fermentation process of the fermentation system is carried out continuously. The mixing tank 1 and the feed tank 4 can cooperate to realize high-frequency interval feeding. After the agricultural waste material preparation is completed in the feed tank, the hydrolysis tank 170 can be fed through the feed tank 4.

[0034] (ii) Close the feed control valve 3 and the acid-generating feed control valve 9, open the hydrolysis feed control valve 7, and form a positive pressure in the feed tank 4 by adjusting the positive and negative pressure control mechanism 5. Under the action of the positive pressure, the reaction material enters the bottom of the hydrolysis tank 170 through the hydrolysis tank feed pipeline 6 for hydrolysis reaction. During the hydrolysis process, the opening of the heat control valve 17 is adjusted according to the temperature data monitored by the temperature sensor 18; when the temperature of the hydrolysis tank 170 exceeds the threshold, the opening of the heat control valve 17 is reduced to reduce the heat input; when the temperature of the hydrolysis tank 170 is lower than the threshold, the opening of the heat control valve 17 is increased to increase the heat input; the hydrolysis temperature of the hydrolysis tank 170 is maintained within a preset temperature range by adjusting the heat input.

[0035] Under the action of positive pressure and gravity, the liquid level of the materials in the hydrolysis tank 170 gradually rises to exceed the height of the first isolation wall 130 and overflows into the acid generation tank 180 through the overflow channel 1130 for acidification reaction. During the acidification process, the opening of the feed control valve 3 is adjusted according to the monitoring data of the organic acid monitoring sensor 21; when the volatile organic acid value is high, the opening of the feed control valve 3 is reduced to reduce the feed amount; when the volatile organic acid value is low, the opening of the feed control valve 3 is increased to increase the feed amount; the reaction process is automatically adjusted to ensure stable and continuous operation of the reaction process.

[0036] (III) During the acidification reaction of the acid generating tank 180, the feed control valve 3 and the hydrolysis feed control valve 7 are closed, and the acid generating feed control valve 9 is opened. By adjusting the positive and negative pressure control mechanism 5, a negative pressure is formed in the feed tank 4. Under the negative pressure, part of the non-acid generating material in the acid generating tank 180 enters the feed tank 4; then the hydrolysis feed control valve 7 and the acid generating feed control valve 9 are closed, and the feed control valve 3 is opened. By adjusting the positive and negative pressure control mechanism 5, a positive pressure is formed in the feed tank 4. Under the positive pressure, the non-acid generating material enters the mixing tank 1 and mixes with the agricultural waste. The beneficial hydrolysis biological flora is brought in by the reflux of the undigested material to enhance the hydrolysis rate.

[0037] (iv) Repeat the above steps to allow the fermentation material to fully react in the hydrolysis tank 170 and the acid production tank 180 of the anaerobic fermentation reactor 10.

[0038] (V) The fermented materials in the acid-producing tank 180 enter the methane-producing tank 190 through the connecting channel 1140 between the isolation wall support columns 150 under the action of their own weight, completing the methane production process. Excess volatile organic acids and water in the methane-producing tank 190 enter the leachate tank 1120 under the action of gravity; part of the leachate in the leachate tank 1120 enters the biogas collection area 1110 through the biogas lifting pipe 160, and then flows back to the acid-producing tank 180 and the hydrolysis tank 170 through the liquid distribution holes 1104 set on the isolation top plate 1100; part of the leachate and particulate matter are extracted through the leachate drainage pipeline 14, and then sucked into the hydrolysis tank 170 by the liquid drainage pump 15 to adjust the pH of the acid-producing tank 180 and the bacterial flora of the hydrolysis tank 170. It should be noted that the isolation top plate 1100 and the methanogen pool 190 are provided with a plurality of small holes for methane gas to pass through, and the methane produced by fermentation in the methanogen pool 190 overflows through the small holes into the biogas collection area 1110 and is then discharged through the biogas discharge pipe 12.

[0039] (VI) After the methanogenesis process is completed, the waste discharge control valve 20 is opened, and the fermentation waste is discharged from the methanogenesis tank 190 through the fermentation waste discharge pipeline 19. The fermentation process of the anaerobic fermentation reactor 10 is a continuous reaction. When the fermentation is running stably, the waste discharge control valve 20 is normally open; at the same time, by adjusting the opening of the waste discharge control valve 20, the fermentation waste is kept full of the inlet end of the fermentation waste discharge pipeline 19 to prevent air from entering the methanogenesis tank 190.

[0040] (VII) After the methanogenesis process is completed, the biogas control valve 13 on the biogas discharge pipe 12 is opened, and the biogas is discharged from the anaerobic fermentation reactor 10 through the biogas discharge pipe 12. The fermentation process of the anaerobic fermentation reactor 10 is a continuous reaction. When the fermentation is running stably, the biogas control valve 13 is normally open; the opening of the biogas control valve 13 is adjusted according to the pressure monitored by the biogas pressure monitoring sensor 11, and the opening of the biogas control valve 13 is adjusted according to the monitoring data of the biogas pressure monitoring sensor 11; when the biogas pressure value is higher than the threshold value, the opening of the biogas control valve 13 is increased to accelerate the discharge of biogas from the biogas collection area 1110; when the biogas pressure value is lower than the threshold value, the opening of the biogas control valve 13 is reduced to reduce the discharge of biogas from the biogas collection area 1110; the pressure in the biogas collection area 1110 is maintained stable to ensure the smooth progress of the fermentation reaction process.

[0041] The above are preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A dry high-pressure anaerobic fermentation system for agricultural waste, characterized in that: The fermentation system comprises: A mixing tank (1), wherein the mixing tank (1) adjusts the moisture content and the concentrations of bicarbonate, hydrogen phosphate and nitrogen in the agricultural waste to provide nutrients for the microorganisms in the fermentation process; A feed tank (4), wherein the feed tank (4) is connected to the mixing tank (1) via a feed pipeline (2), and the discharge port of the feed tank (4) is respectively connected to a hydrolysis tank feed pipeline (6) and an acid generation tank feed pipeline (8); a positive and negative pressure control mechanism (5) is provided in conjunction with the feed tank (4), and the positive and negative pressure control mechanism (5) adjusts the feed tank (4) to be in a positive pressure state or a negative pressure state; control valves are connected to the feed pipeline (2), the hydrolysis tank feed pipeline (6) and the acid generation tank feed pipeline (8); An anaerobic fermentation reactor (10), the anaerobic fermentation reactor (10) comprising a reactor outer wall (110), a first isolation wall (130) and a second isolation wall (140) arranged in a concentric circle from the outside to the inside, a hydrolysis tank (170) is formed between the reactor outer wall (110) and the first isolation wall (130), an acid production tank (180) is formed between the first isolation wall (130) and the second isolation wall (140), a methane production tank (190) is formed in the second isolation wall (140), and the hydrolysis tank feed pipeline (6) and the acid production tank feed pipeline (8) extend from the upper end and are inserted into the bottom of the hydrolysis tank (170) and the acid production tank (180) respectively; wherein: A reactor dome (120) is arranged at the top of the reactor outer wall (110), and an isolation top plate (1100) is arranged between the reactor dome (120) and the reactor outer wall (110), and a biogas collection area (1110) is formed between the isolation top plate (1100) and the reactor dome (120); the top of the first isolation wall (130) is lower than the isolation top plate (1100) to form an overflow channel (1130), the top of the second isolation wall (140) is sealed and connected to the isolation top plate (1100), and the second isolation wall A plurality of isolation wall support columns (150) are evenly distributed in the circumferential direction of the bottom of the isolation wall (140), and the height of the isolation wall support columns (150) is not less than 500m; a connecting channel (1140) connecting the acid generating pool (180) and the methane generating pool (190) is formed between adjacent isolation wall support columns (150); an overflow hole (1150) connecting the acid generating pool (180) is provided on the top side wall of the second isolation wall (140), and the overflow hole (1150) is opened at a position at least 500mm higher than the top height of the first isolation wall (130); A leachate pool (1120) is provided at the bottom of the methane production pool (190), and a plurality of biogas slurry lifting pipes (160) are provided in the methane production pool (190) to connect the leachate pool (1120) and the biogas collection area (1110). The diameter of the biogas slurry lifting pipes (160) is less than 150 mm, and the number of the biogas slurry lifting pipes (160) shall not be less than 3, and the biogas slurry lifting pipes (160) are arranged in a concentric circle in the methane production pool (190); the isolation top plate (110 0) A plurality of liquid distribution holes (1104) are respectively provided on the outer periphery of the biogas slurry lifting pipe (160) and are connected to the biogas collection area (1110) and the hydrolysis tank (170) and the acid generation tank (180); the leachate stored in the leachate tank (1120) enters the biogas collection area (1110) through the biogas slurry lifting pipe (160) and flows into the hydrolysis tank (170) and the acid generation tank (180) through the liquid distribution holes (1104); A fermentation waste discharge pipeline (19) connected to the methane production pool (190) is provided on the side wall of the second isolation wall (140) below the overflow hole (1150), and a waste discharge control valve (20) is connected to the fermentation waste discharge pipeline (19); The reactor dome (120) is provided with a biogas discharge pipe (12), and a biogas control valve (13) is connected to the biogas discharge pipe (12).

2. The dry high-pressure anaerobic fermentation system for agricultural waste according to claim 1, characterized in that: The reactor outer wall (110) and the hydrolysis tank (170) are provided with a heat input pipeline (16) and a temperature sensor (18) respectively. The heat input pipeline (16) is connected to a heat control valve (17). The temperature sensor (18) and the heat control valve (17) are interlocked and controlled, and the opening of the heat control valve (17) is controlled by the temperature sensor (18).

3. The dry high-pressure anaerobic fermentation system for agricultural waste according to claim 2, characterized in that: The bottom plate of the anaerobic fermentation reactor (10) and the leachate pool (1120) are provided with permeation holes corresponding to each other, and the excess volatile organic acid produced by the acid production pool (180) enters the leachate pool (1120) through the permeation holes under the action of gravity and pressure for storage; The leachate pool (1120) is connected to the upper end of the hydrolysis tank (170) via a leachate drainage pipeline (14) and a liquid drainage pump (15) connected thereto; the outlet of the leachate drainage pipeline (14) is installed at a height at least 500 mm higher than the first isolation wall (130); and an organic acid monitoring sensor (21) is connected to the leachate drainage pipeline (14).

4. The dry high-pressure anaerobic fermentation system for agricultural waste according to claim 3, characterized in that: The reactor dome (120) is provided with a biogas pressure monitoring sensor (11) which is in communication with the biogas collection area (1110); the biogas pressure monitoring sensor (11) is interlocked with the biogas control valve (13) and controls the opening of the biogas control valve (13).

5. The dry high-pressure anaerobic fermentation system for agricultural waste according to claim 4, characterized in that: The distance between the bottom end of the hydrolysis tank feed pipeline (6) and the bottom of the hydrolysis tank (170) is less than 2 times the diameter of the hydrolysis tank feed pipeline (6); the distance between the bottom end of the acid generation tank feed pipeline (8) and the bottom of the acid generation tank (180) is 3 / 4 of the height of the first isolation wall (130).

6. A dry high-pressure anaerobic fermentation method for agricultural waste, characterized in that: Using the fermentation system as claimed in claim 5, the fermentation method comprises the following steps: Step 1: The water content, bicarbonate, hydrogen phosphate and nitrogen of the agricultural waste are adjusted to the required concentrations through the mixing tank (1), the hydrolysis feed control valve (7) and the acid generation feed control valve (9) are closed, the feed control valve (3) is opened, and a negative pressure is formed in the feed tank (4) by adjusting the positive and negative pressure control mechanism (5). Under the action of the negative pressure, the reaction materials enter the feed tank (4) through the feed pipeline (2); Step 2: close the feed control valve (3) and the acid-generating feed control valve (9), open the hydrolysis feed control valve (7), and form a positive pressure in the feed tank (4) by adjusting the positive and negative pressure control mechanism (5). Under the positive pressure, the reaction material enters the bottom of the hydrolysis tank (170) through the hydrolysis tank feed pipeline (6) to carry out a hydrolysis reaction; then, under the positive pressure and the action of gravity, the liquid level of the reaction material gradually rises to exceed the height of the first isolation wall (130) and overflows through the overflow channel (1130) into the acid-generating tank (180) to carry out an acidification reaction; Step 3: close the feed control valve (3) and the hydrolysis feed control valve (7), open the acid-generating feed control valve (9), and adjust the positive and negative pressure control mechanism (5) to form a negative pressure in the feed tank (4), so that part of the non-acid-generating material in the acid-generating tank (180) enters the feed tank (4) under the action of the negative pressure; then close the hydrolysis feed control valve (7) and the acid-generating feed control valve (9), open the feed control valve (3), and adjust the positive and negative pressure control mechanism (5) to form a positive pressure in the feed tank (4), so that the non-acid-generating material enters the mixing tank (1) under the action of the positive pressure to mix with the agricultural waste; Step 4: Repeat steps 1 to 3 to allow the fermentation material to fully react in the hydrolysis tank (170) and the acid production tank (180) of the anaerobic fermentation reactor (10); Step 5: The fermented material in the acid production pool (180) enters the methane production pool (190) through the connecting channel (1140) between the isolation wall support columns (150) under the action of its own weight, completing the methane production process; the excess volatile organic acids and water in the methane production pool (190) enter the leachate pool (1120) under the action of gravity; Step 6: After the methanogenesis process is completed, the waste discharge control valve (20) is opened, and the fermentation waste is discharged from the methanogenesis pool (190) through the fermentation waste discharge pipeline (19); the fermentation process of the anaerobic fermentation reactor (10) is a continuous reaction, and the waste discharge control valve (20) is normally open when the fermentation is running stably; at the same time, by adjusting the opening of the waste discharge control valve (20), the fermentation waste is kept filling the inlet end of the fermentation waste discharge pipeline (19) to prevent air from entering the methanogenesis pool (190); Step 7: After the methane production process is completed, the biogas control valve (13) on the biogas discharge pipe (12) is opened, and the biogas is discharged from the anaerobic fermentation reactor (10) through the biogas discharge pipe (12); the fermentation process of the anaerobic fermentation reactor (10) is a continuous reaction, and the biogas control valve (13) is normally open when the fermentation is running stably; the opening of the biogas control valve (13) is adjusted according to the pressure monitored by the biogas pressure monitoring sensor (11) to maintain the pressure of the biogas collection area (1110) stable, so as to ensure that the fermentation reaction process proceeds smoothly.

7. The dry high-pressure anaerobic fermentation method for agricultural waste according to claim 6, characterized in that: In step 5, part of the leachate in the leachate pool (1120) enters the biogas collection area (1110) through the biogas lifting pipe (160), and then flows back to the acid production pool (180) and the hydrolysis pool (170) through the liquid distribution holes (1104) provided on the isolation top plate (1100); part of the leachate and particulate matter are extracted through the leachate drainage pipeline (14), and then are sucked and discharged into the hydrolysis pool (170) through the liquid drainage pump (15), so as to adjust the pH of the acid production pool (180) and the bacterial flora of the hydrolysis pool (170).

8. The dry high-pressure anaerobic fermentation method for agricultural waste according to claim 6, characterized in that: In step 2, the opening of the heat control valve (17) is adjusted according to the temperature data monitored by the temperature sensor (18); when the temperature of the hydrolysis tank (170) exceeds a threshold value, the opening of the heat control valve (17) is reduced to reduce the heat input; when the temperature of the hydrolysis tank (170) is lower than the threshold value, the opening of the heat control valve (17) is increased to increase the heat input; and the hydrolysis temperature of the hydrolysis tank (170) is maintained within a preset temperature range by adjusting the heat input.

9. The dry high-pressure anaerobic fermentation method for agricultural waste according to claim 6, characterized in that: During steps 1 and 2, the opening of the feed control valve (3) is adjusted according to the monitoring data of the organic acid monitoring sensor (21); when the volatile organic acid value is high, the opening of the feed control valve (3) is reduced to reduce the feed amount; when the volatile organic acid value is low, the opening of the feed control valve (3) is increased to increase the feed amount; the reaction process is automatically adjusted to ensure stable and continuous operation of the reaction process.

10. The dry high-pressure anaerobic fermentation method for agricultural waste according to claim 6, characterized in that: In step 7, the opening of the biogas control valve (13) is adjusted according to the monitoring data of the biogas pressure monitoring sensor (11); when the biogas pressure value is higher than a threshold value, the opening of the biogas control valve (13) is increased to accelerate the discharge of biogas from the biogas collection area (1110); when the biogas pressure value is lower than the threshold value, the opening of the biogas control valve (13) is reduced to reduce the discharge of biogas from the biogas collection area (1110); and the pressure of the biogas collection area (1110) is maintained stable.

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