A dry high-temperature methane in-situ enrichment system for fiber raw materials

Abstract

The utility model discloses a kind of fiber raw material dry high-temperature methane in-situ enrichment systems, including mixing tank, for receiving anaerobic fermentation raw material and fully mixing;Feed tank, be communicated with mixing tank by feed pipeline, anaerobic fermentation reactor, be divided into hydrolysis pool, acid production pool and methane production pool, wherein, the hydrolysis pool and acid production pool are separated by hydrolysis acid production pool flow guide plate and top intercommunication, the methane production pool is independently arranged, and its top end is equipped with the dome of marsh gas gathering, dome top is equipped with marsh gas discharge pipeline and marsh gas on-line analysis control device. The utility model can solve the problem of acid inhibition caused by the low content of biogas methane produced by fiber raw materials, the waste of resources caused by direct discharge of decarburization tail gas and the accumulation of carbon dioxide.

Description

Technical Field

[0001] This utility model relates to the field of anaerobic fermentation of straw to produce biogas, specifically to a dry high-temperature in-situ methane enrichment system for fibrous raw materials. Background Technology

[0002] Dry high-temperature anaerobic fermentation of straw has become a research hotspot due to its advantages such as large gas production, high operating costs, and no biogas slurry discharge. However, the biogas produced by straw anaerobic fermentation has a low methane content (about 50-65%) and a high carbon dioxide content (20-40%). The high investment and operating costs for decarbonization make biogas less competitive compared with pipeline natural gas.

[0003] In-situ methane enrichment technology reduces carbon dioxide produced during the fermentation process or externally injected carbon dioxide into methane in an anaerobic fermentation reactor under high temperature conditions. This can significantly increase the methane content of biogas in the anaerobic fermentation process (methane content > 80%), making it possible for straw-based biogas to be competitive in the market.

[0004] Currently, the domestic method of producing biogas from straw through anaerobic fermentation has the following shortcomings: (1) Anaerobic fermentation under normal or slightly positive pressure results in slow straw hydrolysis rate, low anaerobic fermentation gas production rate, high unit equipment investment for biogas, and lack of market competitiveness. Increasing the anaerobic fermentation pressure can accelerate the hydrolysis rate of complex organic matter and effectively shorten the fermentation cycle. However, in conventional anaerobic fermentation reactors, straw hydrolysis, acidification, and methanogenesis occur in the same closed space, and carbon dioxide accumulates in the fermentation residue. It is difficult to control the acidification and methanogenesis processes of fermentation materials, which seriously affects the stability of the anaerobic fermentation process.

[0005] (2) The methane content of biogas in the anaerobic fermentation process is not high, about 50%~65%, and the other components are mainly carbon dioxide, resulting in high decarbonization costs. After biogas purification and decarbonization, the tail gas is basically high-concentration greenhouse gas carbon dioxide, which is directly emitted, resulting in a waste of carbon dioxide resources.

[0006] (3) The acid production tank and methanogenic tank of the anaerobic fermentation reactor are connected. It is difficult to avoid the acid inhibition of subsequent methanogenic formation by the low pH of the acid production stage, which may cause fermentation to stop in severe cases.

[0007] (4) Under low pressure, the solubility of carbon dioxide in fermentation materials is low, and the in-situ enrichment of methane to produce biogas is not economically viable; under high pressure, the concentration of carbon dioxide is high, and due to the mass transfer barrier in dry fermentation, the fermentation materials are easily acidified, forming acid inhibition or even causing anaerobic fermentation to stop. (5) In order to reduce the pH of the hydrolysis tank and increase the rate of straw hydrolysis, a large amount of fermentation material from the acid-producing tank needs to be extracted and returned to the hydrolysis tank, resulting in low efficiency of the anaerobic fermentation equipment. Summary of the Invention

[0008] To address the shortcomings of existing anaerobic fermentation processes for producing biogas from straw, the technical objective of this invention is to provide a dry high-temperature in-situ methane enrichment system for fibrous raw materials. This system can solve the problems of high subsequent processing costs due to low methane content in biogas produced from fibrous raw materials, resource waste caused by direct emission of decarbonization tail gas, and acid inhibition caused by carbon dioxide accumulation.

[0009] To achieve the above-mentioned technical objectives, the present invention employs the following technical means: A dry high-temperature in-situ methane enrichment system for fibrous raw materials includes: A mixing tank is used to receive and thoroughly mix anaerobic fermentation raw materials. The feed tank is connected to the mixing tank via a feed pipeline, and a feed pipeline control valve is installed on the feed pipeline. An anaerobic fermentation reactor is divided into a hydrolysis tank, an acid production tank, and a methanogenic tank. The hydrolysis tank and the acid production tank are separated by a guide plate for the hydrolysis and acid production tank and are connected at the top. The methanogenic tank is set up independently and is equipped with a dome for collecting biogas at its top. A biogas discharge pipeline and an online biogas analysis and control device are installed on the top of the dome. A low-pressure gas-gathering valve and a high-pressure gas-releasing valve are installed sequentially along the biogas flow direction on the biogas discharge pipeline. The anaerobic fermentation reactor is equipped with a pressure monitoring device for the hydrolysis acid production tank and a liquid level monitoring device for the hydrolysis acid production tank on its outer wall. Bottom of the feed tank: The feed pipeline to the hydrolysis tank is connected to the hydrolysis tank. The acid production tank is connected to the acid production tank via a discharge pipeline. The feed pipeline to the methanogenic cell is connected to the methanogenic cell. Control valves are installed on the feed pipeline of the hydrolysis tank, the discharge pipeline of the acid production tank, and the feed pipeline of the methan production tank. Positive and negative pressure control device, installed in conjunction with the feed tank, is used to adjust the positive / negative pressure state inside the feed tank; The hydrogenation pipeline is connected to the feed pipeline of the methanogenic pool; A carbon dioxide supply line is connected to the feed line of the hydrolysis tank. The biogas slurry pipeline is connected to the hydrogenation pipeline.

[0010] Beneficial effects:

[0011] First, the anaerobic fermentation reactor is divided into a hydrolysis tank, an acid production tank, and a methanogenic tank, each with its own independent space. This facilitates the formation of optimal environments for each tank, improving the rates of hydrolysis, acid production, and methanogenesis, and increasing the reactor's gas production efficiency. At the same time, it avoids acidification and acid production from lowering the pH, which could inhibit subsequent methanogenesis and improve the process stability of the anaerobic fermentation system.

[0012] Secondly, a pressure monitoring device for the hydrolysis acid production tank is installed on the outer wall of the anaerobic fermentation reactor to detect the gas pressure in the sealed space of the hydrolysis tank and the acid production tank of the anaerobic fermentation reactor. The opening of the control valve of the carbon dioxide addition pipeline is adjusted by the pressure signal to control the amount of carbon dioxide gas dissolved into the fermentation material, thereby indirectly adjusting the pH of the straw hydrolysis tank, increasing the activity of cellulase, and promoting the hydrolysis of straw.

[0013] Third, an online biogas analysis and control device is installed on the top of the biogas collection chamber to detect the gas composition of the biogas collection chamber. When the hydrogen concentration exceeds the threshold, the hydrogen concentration threshold is adjusted according to the biogas methane concentration, with a maximum of no more than 3.5%, and the opening of the hydrogen addition pipeline control valve is reduced to reduce the amount of hydrogen entering. When the carbon dioxide / hydrogen ratio is greater than the ratio of added carbon dioxide and hydrogen, the opening of the carbon dioxide addition pipeline control valve is reduced to reduce the amount of hydrogen entering, thereby reducing hydrogen waste and ensuring the calorific value of natural gas.

[0014] In one optional embodiment, the anaerobic fermentation reactor includes an outer wall of the anaerobic fermentation reactor arranged concentrically from the outside in, a guide plate for the hydrolysis acid-producing tank, and an outer wall of the methanogenic tank; a hydrolysis tank is formed between the outer wall of the anaerobic fermentation reactor and the guide plate for the hydrolysis acid-producing tank, an acid-producing tank is formed between the guide plate for the hydrolysis acid-producing tank and the outer wall of the methanogenic tank, and a methanogenic tank is formed inside the outer wall of the methanogenic tank; a top plate for the hydrolysis acid-producing tank is installed between the top of the outer wall of the anaerobic fermentation reactor and the outer wall of the methanogenic tank, sealing the hydrolysis tank and the acid-producing tank.

[0015] In one optional embodiment, a biogas residue discharge pipeline is provided at the upper end of the outer wall of the methanogenic tank. The biogas residue discharge pipeline is installed at the upper part of the outer wall of the methanogenic tank, which is higher than the height of the outer wall of the anaerobic fermentation reactor. A biogas residue discharge pipeline control valve is installed on the biogas residue discharge pipeline.

[0016] Beneficial effects: The biogas residue discharge pipeline is installed at the upper part of the outer wall of the methanogenic tank, which is higher than the outer wall of the anaerobic fermentation reactor. This can avoid pipeline corrosion problems caused by the biogas residue pipeline crossing the hydrolysis tank and acid production tank of the anaerobic fermentation reactor, and reduce equipment maintenance costs.

[0017] In one optional embodiment, a dome and a perforated plate for the methanogenic pool are installed at the top of the pool, and a biogas collection chamber is formed between the dome and the perforated plate.

[0018] Beneficial effects: Installing a perforated plate for the methanogenic tank at the bottom of the biogas collection chamber prevents the rapid pressure change in the methanogenic tank from impacting the fermentation process when the biogas collection chamber releases gas and depressurizes quickly, and also prevents anaerobic fermentation residues from entering the biogas collection chamber with the rapid gas release.

[0019] In one optional embodiment, the feed pipeline of the hydrolysis tank, the discharge pipeline of the acid-producing tank, and the feed pipeline of the methanogenic tank are no more than 500 mm away from the bottom of the anaerobic fermentation reactor. The connection point between the biogas slurry pipeline and the hydrogenation pipeline is located after the control valve of the hydrogenation pipeline, with a distance of not less than 75 mm from the control valve and a distance of not less than 125 mm from the connection point between the hydrogenation pipeline and the feed pipeline of the methanogenic tank, to ensure that hydrogen is uniformly dissolved in the biogas slurry within the hydrogenation pipeline. The connection point between the hydrogenation pipeline and the methanogenic pool feed pipeline is located at the rear end of the control valve of the methanogenic pool feed pipeline.

[0020] Beneficial effects: The biogas slurry pipeline is installed after the control valve of the hydrogenation pipeline, at a distance of not less than 75mm from the control valve and at a distance of not less than 125mm from the connection point between the hydrogenation pipeline and the feed pipeline of the methanogenic tank, to ensure that hydrogen is uniformly dissolved in the biogas slurry within the hydrogenation pipeline. The hydrogenation pipeline is installed after the control valve of the methanogenic tank feed pipeline to prevent the fermentation material from drying and clogging at the interface between the hydrogenation pipeline and the methanogenic tank feed pipeline; the preferred connection method is a ring installation to improve the uniformity of mixing hydrogen and acidified materials. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the dry high-temperature methane in-situ enrichment system for fiber-based raw materials according to this utility model. Wherein, A: Hydrolysis tank; B: Acid-producing tank; C: Methanogenic tank; D: Biogas collection chamber; 1: Mixing tank; 2: Feed tank; 3: Positive and negative pressure control device; 4: Anaerobic fermentation reactor; 5: Pressure stabilizing device; 501: Pressure stabilizing tank; 502: One-way breathing valve; Q401: External wall of anaerobic fermentation reactor; Q402: Guide plate of hydrolysis acid-producing tank; Q403: External wall of methanogenic tank; Q404: Top plate of hydrolysis acid-producing tank; Q405: Perforated plate of methanogenic tank; Q406: Biogas collection chamber; G101: Feed pipeline; G102: Feed pipeline control valve; G201: Feed pipeline of hydrolysis tank. G202: Control valve for feed line to hydrolysis tank; G301: Discharge line to acidification tank; G302: Control valve for discharge line to acidification tank; G401: Feed line to methanogenesis tank; G402: Control valve for feed line to methanogenesis tank; G501: Hydrogenation line; G502: Control valve for hydrogenation line; G601: Carbon dioxide addition line; G602: Control valve for carbon dioxide addition; G603: Pressure stabilizing line; G604: Pressure reducing valve for pressure stabilizing line; G701: Sludge discharge line; G702: Control valve for sludge discharge line; G801: Slurry line; G802: Control valve for slurry line. G901: Biogas discharge pipeline; G902: High-pressure gas release valve; G904: Low-pressure gas gathering valve; Y101: Hydrolysis acid production tank pressure monitoring device; Y102: Hydrolysis acid production tank liquid level monitoring device; Y103: Biogas online analysis and control device; Y104: Methanogenic tank liquid level monitoring device. Detailed Implementation

[0022] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. Example 1

[0023] like Figure 1 As shown, a dry high-temperature in-situ methane enrichment system for fibrous raw materials includes: Mixing tank 1 is used to receive anaerobic fermentation raw materials and mix them thoroughly. Feed tank 2 is connected to mixing tank 1 through feed pipe G101. Feed pipe control valve G102 is installed on feed pipe G101. The anaerobic fermentation reactor 4 includes an outer wall Q401, a hydrolysis acid-producing tank guide plate Q402, and a methanogenic tank outer wall Q403 arranged concentrically from the outside in. A hydrolysis tank A is formed between the outer wall Q401 and the hydrolysis acid-producing tank guide plate Q402; an acid-producing tank B is formed between the hydrolysis acid-producing tank guide plate Q402 and the methanogenic tank outer wall Q403; and a methanogenic tank C is formed inside the methanogenic tank outer wall Q403. A hydrolysis acid-producing tank top plate Q404 is installed at the top of the outer wall Q401, sealing the hydrolysis tank A and the acid-producing tank B. A biogas-gathering dome Q406 is installed at the top of the methanogenic tank C, and a biogas discharge pipe G901 is installed at the top of the dome Q406. The hydrolysis tank is equipped with a hydrolysis acid production tank pressure monitoring device Y101 and a hydrolysis acid production tank liquid level monitoring device Y102. Bottom of the feed tank 2: The feed pipeline G101 is connected to the hydrolysis tank A. The acid production tank B is connected via the acid production tank discharge pipeline G301. The methanogenic cell is connected to the methanogenic cell C via the feed pipeline G401. Control valves are installed on the feed pipeline G101 of the hydrolysis tank, the discharge pipeline G301 of the acid production tank, and the feed pipeline G401 of the methan production tank. Positive and negative pressure control device 3 is installed in the feed tank 2 to regulate the positive / negative pressure state inside the feed tank 2; Hydrogenation line G501 is connected to the methanogenic pool feed line G401; The carbon dioxide supply line G601 is connected to the feed line G101 of the hydrolysis tank. The biogas slurry pipeline G801 is connected to the hydrogenation pipeline G501; The pressure monitoring device Y101 for the hydrolysis acid production tank is installed on the outer wall Q401 of the anaerobic fermentation reactor. A low-pressure gas-gathering valve G904 and a high-pressure gas-releasing valve G902 are installed sequentially along the biogas flow direction on the biogas discharge pipeline G901. The top of the biogas collection chamber D is equipped with a biogas online analysis and control device Y103.

[0024] First, the anaerobic fermentation reactor is divided into a hydrolysis tank, an acid production tank, and a methanogenic tank, each with its own independent space. This facilitates the formation of optimal environments for each tank, improving the rates of hydrolysis, acid production, and methanogenesis, and increasing the reactor's gas production efficiency. At the same time, it avoids acidification and acid production from lowering the pH, which could inhibit subsequent methanogenesis and improve the process stability of the anaerobic fermentation system.

[0025] Secondly, a pressure monitoring device for the hydrolysis acid production tank is installed on the outer wall of the anaerobic fermentation reactor to detect the gas pressure in the sealed space of the hydrolysis tank and the acid production tank of the anaerobic fermentation reactor. The opening of the control valve of the carbon dioxide addition pipeline is adjusted by the pressure signal to control the amount of carbon dioxide gas dissolved into the fermentation material, thereby indirectly adjusting the pH of the straw hydrolysis tank, increasing the activity of cellulase, and promoting the hydrolysis of straw.

[0026] Third, an online biogas analysis and control device is installed on the top of the biogas collection chamber to detect the gas composition of the biogas collection chamber; when the hydrogen concentration exceeds the threshold, the hydrogen concentration threshold is adjusted according to the biogas methane concentration, not exceeding 3.5%, and the opening of the hydrogen addition pipeline control valve is reduced to reduce the amount of hydrogen entering; when the carbon dioxide / hydrogen ratio is greater than the ratio of added carbon dioxide and hydrogen, the opening of the carbon dioxide addition pipeline control valve is reduced to reduce the amount of hydrogen entering. Example 2

[0027] In this embodiment, a biogas residue discharge pipe G701 is provided at the upper end of the outer wall Q403 of the methanogenic tank. The biogas residue discharge pipe G701 is installed at the upper part of the outer wall Q403 of the methanogenic tank, higher than the height of the outer wall Q401 of the anaerobic fermentation reactor. A biogas residue discharge pipe control valve G702 is installed on the biogas discharge pipe G701. A biogas discharge pipe G901 is installed in the biogas collection chamber D. This embodiment can avoid the pipe corrosion problem caused by the biogas residue pipe G701 passing through the hydrolysis tank A and acid production tank B of the anaerobic fermentation reactor, and reduce equipment maintenance costs.

[0028] As a further preferred embodiment of the technical solutions of Embodiment 1 and Embodiment 2, the feed pipeline G201 of the hydrolysis tank, the discharge pipeline G301 of the acid production tank and the feed pipeline G401 of the methanogenic tank are no more than 500mm away from the bottom of the anaerobic fermentation reactor 4. The connection point between the biogas slurry pipeline G801 and the hydrogenation pipeline G501 is located after the hydrogenation pipeline control valve G502, at a distance of not less than 75 mm from the hydrogenation pipeline control valve, and at a distance of not less than 125 mm from the connection point between the hydrogenation pipeline G501 and the methanogenic tank feed pipeline G401, to ensure that hydrogen is uniformly dissolved with biogas slurry in the hydrogenation pipeline G501; the connection point between the hydrogenation pipeline G501 and the methanogenic tank feed pipeline G401 is located at the rear end of the methanogenic tank feed pipeline control valve G402. In this further optimized technical solution, the biogas slurry pipeline G801 is installed after the hydrogenation pipeline control valve G502, with a distance of not less than 3 times the pipe diameter (one pipe diameter is DN25) from the hydrogenation pipeline control valve, and a distance of not less than 5 times the pipe diameter from the connection point between the hydrogenation pipeline G501 and the methanogenic tank feed pipeline G401, ensuring that hydrogen is uniformly dissolved with biogas slurry in the hydrogenation pipeline G501; the hydrogenation pipeline G501 is installed after the methanogenic tank feed pipeline control valve G402 to prevent the fermentation material from drying and clogging at the interface between the hydrogenation pipeline G501 and the methanogenic tank feed pipeline G401; the preferred connection method is a ring installation to improve the uniformity of mixing hydrogen and acidified materials.

[0029] The in-situ enrichment method of the dry high-temperature methane in-situ enrichment system for fibrous raw materials of this invention includes the following steps: Step 1: Mix the fermentation raw materials and inoculum evenly through mixing tank 1; close the control valve G202 of the hydrolysis tank feed pipeline, the control valve G302 of the acid production tank discharge pipeline, and the control valve G402 of the methanogenic tank feed pipeline, and open the feed pipeline control valve G102. Place the feed tank 2 under negative pressure through the positive and negative pressure control device 3, and the material in the mixing tank 1 is drawn into the feed tank 2. Close the feed pipeline control valve G102, the acid-producing tank discharge pipeline control valve G302, and the methanogenic tank feed pipeline control valve G402. Open the hydrolysis tank feed pipeline control valve G202 and the carbon dioxide injection pipeline control valve G602. The positive and negative pressure control device 3 places the feed tank 2 under positive pressure. The material, high-pressure carbon dioxide, and other materials in the feed tank 2 diffuse and mix in the hydrolysis tank feed pipeline. Under pressure, the mixture enters the bottom of the hydrolysis tank A. Under pressure and gravity, the liquid level of the hydrolyzed material rises and overflows into the acid-producing tank B. The hydrolysis acid production tank level monitoring device Y102 detects the material level in hydrolysis tank A and acid production tank B. When the level exceeds the threshold, the hydrolysis tank feed pipeline control valve G202 is closed. At the same time, the positive and negative pressure control device 3 is set to 0 pressure to stop the material in the feed tank 2 from entering the hydrolysis tank A. The hydrolysis acid production tank pressure monitoring device Y101 detects the gas pressure in hydrolysis tank A and acid production tank B. When the pressure exceeds the set value, the carbon dioxide pipeline control valve G601 is closed to stop the carbon dioxide gas from being sent into hydrolysis tank A. Step 2: Close the feed pipeline control valve G102, the hydrolysis tank feed pipeline control valve G202, the methanogenic tank feed pipeline control valve G402, and the carbon dioxide injection pipeline control valve G602; open the acid production tank discharge pipeline control valve G302; place the feed tank 2 under negative pressure through the positive and negative pressure control device 3, and the hydrolyzed material at the bottom of the acid production tank B is drawn into the feed tank 2; Step 3: Close the control valve G202 of the feed pipeline of the hydrolysis tank, the control valve G302 of the discharge pipeline of the acid production tank, and the control valve G402 of the feed pipeline of the methanogenic tank, and open the control valve G102 of the feed pipeline; put the feed tank 2 into a positive pressure state through the positive and negative pressure control device 3, and the material in the feed tank 2 enters the mixing tank 1 under pressure, mixes with the fermentation raw materials and inoculum, recovers and utilizes hydrolytic enzymes and hydrolytic bacteria and completes colonization; Step 4: Close the control valve G202 of the hydrolysis tank feed pipeline, the control valve G302 of the acid production tank discharge pipeline, and the control valve G402 of the methanogenic tank feed pipeline; open the feed pipeline control valve G102; put the feed tank 2 into a negative pressure state through the positive and negative pressure control device 3, and pump the material that has completed colonization in the mixing tank 1 into the feed tank 2; Step 5: Close the feed pipeline control valve G102, the hydrolysis tank feed pipeline control valve G202, and the acid production tank discharge pipeline control valve G302; first open the biogas slurry pipeline control valve G802 and the hydrogenation pipeline control valve G502, and hydrogen and biogas slurry mix in the hydrogenation pipeline G501; then open the methanogenic tank feed pipeline control valve G402, and place the feed tank 2 under positive pressure through the positive and negative pressure control device 3. The material in the feed tank 2 diffuses and mixes with hydrogen and biogas slurry in the methanogenic tank feed pipeline G401, and enters the bottom of the methanogenic tank C under pressure; under high temperature conditions, hydrogen-nutritive methanation is extremely active, and hydrogen and carbon dioxide are rapidly converted into methane; then it enters the biogas collection chamber D through the perforated plate Q405 of the methanogenic tank; The methanogenic pool level monitoring device Y104 detects the liquid level height of the methanogenic pool C. When the liquid level exceeds the threshold, the control valve G402 of the methanogenic pool feed pipeline is closed. At the same time, the positive and negative pressure control device 3 is set to the 0 pressure state to stop the material in the feed tank 2 from entering the methanogenic pool C. The biogas online analysis and control device Y103 monitors biogas components in real time. When the hydrogen content in the biogas exceeds the threshold, it reduces or closes the opening of the hydrogenation pipeline control valve G502 and the biogas slurry pipeline control valve G802, reducing or stopping the supply of hydrogen to the methanogenic pool C. At the same time, it puts the low-pressure gas-gathering valve G904 and the high-pressure gas-releasing valve G902 into the locked state until all the hydrogen is converted into methane, and then puts the low-pressure gas-gathering valve G904 and the high-pressure gas-releasing valve G902 into the activated state. Step 6: When the pressure inside the biogas collection chamber D is higher than the first pressure threshold of 0.7 MPa, the high-pressure release valve G902 opens and biogas is discharged; when the biogas pressure is lower than the first pressure threshold of 0.7 MPa, the low-pressure gas collection valve G904 closes and biogas discharge stops.

[0030] As a further optimization of the above-mentioned in-situ enrichment method, it also includes: The pressure stabilizing device 5 includes a pressure stabilizing tank 501 and a pressure stabilizing pipeline G603. The pressure stabilizing tank 501 is connected to the anaerobic fermentation reactor 4 and the carbon dioxide addition pipeline G601 through the pressure stabilizing pipeline G603. When the pressure inside the anaerobic fermentation reactor 4 exceeds the second pressure threshold of 0.01 MPa, the high-pressure gas enters the pressure stabilizing tank 501 through the pressure stabilizing pipeline G603. The pressure stabilizing tank 501 is equipped with a one-way breathing valve 502. When the one-way breathing valve 502 is opened, it discharges high-pressure gas and reduces the pressure in the closed space of hydrolysis tank A and acid production tank B. In other words, the carbon dioxide content in the anaerobic fermentation reactor 4 is controlled to be maintained within a certain range by the one-way breathing valve 502 for subsequent hydrogen-nutritive methanation reaction, thus avoiding excessive carbon dioxide gas in the methanation process. The pressure stabilizing tank 501 is connected to the carbon dioxide addition pipeline G601 and the pressure of the pressure stabilizing tank 501 is kept stable through the carbon dioxide addition pipeline control valve G602, thereby keeping the carbon dioxide partial pressure in the closed space of hydrolysis tank A and acid production tank B stable, indirectly optimizing the pH of the hydrolysis tank to the optimal hydrolysis conditions, and reducing the material return flow after acid production while increasing the straw hydrolysis rate.

[0031] When the gas pressure in the sealed space of hydrolysis tank A and acid production tank B of anaerobic fermentation reactor 4 exceeds the threshold, the excess carbon dioxide gas is discharged through one-way breathing valve 502 to avoid the excessive carbon dioxide pressure inhibiting the straw hydrolysis rate.

[0032] Furthermore, the carbon dioxide comes from the tail gas after biogas purification and decarbonization. The main component of this gas is high-concentration, high-pressure carbon dioxide, with a pressure of approximately 0.8 to 1 MPa.

[0033] Furthermore, the pressure stabilizing pipeline G603 is installed between the pressure stabilizing tank 5 and the anaerobic fermentation reactor 4, and the pressure reducing valve G604 is installed between the carbon dioxide adding pipeline G602 and the pressure stabilizing tank 501. The carbon dioxide gas pressure at the outlet of the pressure reducing valve G604 is used as the pressure stabilizing source to avoid gas pressure fluctuations in the sealed space of the anaerobic fermentation reactor 4, hydrolysis tank A and acid production tank B. A one-way breather valve 502 is installed on the pressure stabilizing tank 501.

Claims

1. A dry high-temperature in-situ methane enrichment system for fibrous raw materials, comprising: Mixing tank (1) is used to receive anaerobic fermentation raw materials and mix them thoroughly; The feed tank (2) is connected to the mixing tank (1) through the feed pipeline (G101), and the feed pipeline control valve (G102) is installed on the feed pipeline (G101). The anaerobic fermentation reactor (4) is characterized in that it is divided into a hydrolysis tank, an acid production tank and a methanogenic tank. The hydrolysis tank and the acid production tank are separated by a guide plate (Q402) and connected at the top. The methanogenic tank (C) is set up independently and is equipped with a dome (Q406) for collecting biogas at its top. A biogas discharge pipeline (G901) and a biogas online analysis and control device (Y103) are installed on the top of the dome (Q406). A low-pressure gas-gathering valve (G904) and a high-pressure gas-releasing valve (G902) are installed sequentially along the biogas flow direction on the biogas discharge pipeline (G901). The anaerobic fermentation reactor (4) is equipped with a hydrolysis acid production tank pressure monitoring device (Y101) and a hydrolysis acid production tank liquid level monitoring device (Y102) on the outer wall (Q401) of the anaerobic fermentation reactor. Bottom of the feed tank (2): It is connected to the hydrolysis tank (A) via the feed pipe (G101); It is connected to the acid-producing tank (B) via the acid-producing tank discharge pipeline (G301); The methanogenic cell is connected to the methanogenic cell (C) via the feed line (G401); Control valves are installed on the feed pipeline (G101) of the hydrolysis tank, the discharge pipeline (G301) of the acid production tank, and the feed pipeline (G401) of the methan production tank. Positive and negative pressure control device (3) is installed in the feed tank (2) to adjust the positive / negative pressure state in the feed tank (2); The hydrogenation line (G501) is connected to the methanogenic pool feed line (G401); A carbon dioxide supply line (G601) is connected to the feed line (G101) of the hydrolysis tank; The biogas slurry pipeline (G801) is connected to the hydrogenation pipeline (G501).

2. The dry high-temperature in-situ methane enrichment system for fibrous raw materials according to claim 1, characterized in that, The anaerobic fermentation reactor (4) includes an outer wall (Q401) of the anaerobic fermentation reactor arranged concentrically from the outside to the inside, a guide plate (Q402) for the hydrolysis acid production tank, and an outer wall (Q403) for the methanogenic tank. A hydrolysis tank (A) is formed between the outer wall (Q401) of the anaerobic fermentation reactor and the guide plate (Q402) for the hydrolysis acid production tank. An acid production tank (B) is formed between the guide plate (Q402) for the hydrolysis acid production tank and the outer wall (Q403) for the methanogenic tank. A methanogenic tank (C) is formed inside the outer wall (Q403) for the methanogenic tank. A top plate (Q404) for the hydrolysis acid production tank is installed between the top of the outer wall (Q401) of the anaerobic fermentation reactor and the outer wall of the methanogenic tank (Q403), sealing the hydrolysis tank (A) and the acid production tank (B).

3. The dry high-temperature in-situ methane enrichment system for fibrous raw materials according to claim 2, characterized in that, The upper end of the outer wall (Q403) of the methanogenic tank is provided with a biogas residue discharge pipe (G701). The biogas residue discharge pipe (G701) is installed at the upper part of the outer wall (Q403) of the methanogenic tank, which is higher than the height of the outer wall (Q401) of the anaerobic fermentation reactor. A biogas residue discharge pipe control valve (G702) is installed on the biogas residue discharge pipe (G701).

4. The dry high-temperature in-situ methane enrichment system for fibrous raw materials according to claim 1, characterized in that, The top of the methanogenic tank is equipped with a dome and a perforated plate for the methanogenic tank, and a biogas collection chamber is formed between the dome and the perforated plate for the methanogenic tank.

5. The dry high-temperature in-situ methane enrichment system for fibrous raw materials according to claim 1, characterized in that, The feed pipeline (G201) of the hydrolysis tank, the discharge pipeline (G301) of the acid production tank and the feed pipeline (G401) of the methanogenic tank shall be no more than 500 mm away from the bottom of the anaerobic fermentation reactor (4); The connection point between the biogas slurry pipeline (G801) and the hydrogenation pipeline (G501) is located after the hydrogenation pipeline control valve (G502), at a distance of not less than 75mm from the hydrogenation pipeline control valve, and at a distance of not less than 125mm from the connection point between the hydrogenation pipeline (G501) and the methanogenic tank feed pipeline (G401), to ensure that hydrogen is uniformly dissolved with biogas slurry in the hydrogenation pipeline (G501); The connection point between the hydrogenation pipeline (G501) and the methanogenic pool feed pipeline (G401) is located at the rear end of the control valve (G402) of the methanogenic pool feed pipeline.

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