A floating membrane cover device for collecting biogas

Abstract

The present invention discloses a floating membrane cover device for collecting biogas, and relates to the field of biogas collection and treatment technology. The present invention is arranged on the top of an anaerobic reactor, and the floating membrane cover device includes a floating membrane cover composed of an outer membrane cover, a heat-insulating interlayer of an intermediate layer, and an insulating film of an inner layer, a rainwater collection and fallback structure, a sampling port structure, a buoy structure, and a fixed plastic pipe chain; the fixed plastic pipe chain is pressed down on the upper part of the floating membrane cover to form a rainwater drainage trough toward the rainwater collection and fallback structure; a biogas collection and storage space is formed between the floating membrane cover and the internal liquid level of the anaerobic reactor and at the lower peripheral side of the connected position. The floating membrane cover of the present invention can prevent the rainwater collection and fallback device from leaking biogas, effectively prevent rainwater from forming irregular grooves above the membrane cover, and does not need to use a rainwater pump to suck rainwater, so the operation is simple and safe; it is also convenient to sample and measure wastewater and sludge in the anaerobic reactor.

Description

Technical Field

[0001] The invention belongs to the technical field of biogas collection and processing, and in particular relates to a floating membrane cover device for collecting biogas. Background Art

[0002] Anaerobic processes are widely used in the anaerobic treatment of high-concentration organic wastewater in China. The structural form of anaerobic reactors can be divided into square or rectangular civil structures, and the tank body generally adopts a circular structure. According to the different designs of anaerobic reactors, the top of the anaerobic reactor can be designed to be completely enclosed, which can be sealed with a concrete structure or a steel structure. It can also be designed to be open at the top according to the different anaerobic processes adopted. At this time, it is usually necessary to add a cover or a closed structure to collect and treat the waste gas generated by the top water outlet. When a concrete structure and a completely enclosed anaerobic reactor are used, the top of the reactor is completely sealed with concrete, which has the problems of high engineering cost and inconvenient maintenance. In addition, with the improvement of domestic environmental protection emission standards, the treatment of manure and sewage in the domestic livestock and poultry breeding industry is becoming an increasingly urgent problem facing the country. At present, the following treatment methods are usually adopted in the domestic livestock and poultry breeding industry for the management and treatment of manure and sewage: (1) Solid manure and sewage are separated for anaerobically treatment and then composting, or directly aerobic composting. The sewage is treated by conventional UASB anaerobic process. The wastewater after anaerobically treatment is built into a large-scale stable storage tank with a retention time of up to 6 to 12 months, and returned to the field in the appropriate season; (2) The separated sewage is directly treated anaerobically and stored in a large-scale "pit-type" black film biogas digester for biogas storage, and returned to the field in the appropriate season.

[0003] In recent years, due to its low investment, black film biogas digesters have become a popular choice for large domestic breeding enterprises, especially large-scale pig farming enterprises with large wastewater production. A large number of black film biogas digesters have been built for anaerobic treatment and storage of pig wastewater. Common black film biogas digesters often adopt the form of a sloped "earth pit", that is, digging a hole in the ground. Figure 1The pit of the shape shown in the figure has an HDPE anti-seepage membrane laid at the bottom and on the slope of the pit, and a wastewater inlet pipe and wastewater and sludge discharge pipes are arranged through the pit. A single-layer HDPE anti-seepage membrane is used on the upper part of the wastewater and is bonded to the bottom anti-seepage membrane laid on the slope to form an internal biogas storage space, which can be discharged or utilized through a biogas discharge pipe 9. Although this type of black film biogas anaerobic tank has a simple structure and low cost, it has the following obvious disadvantages: (1) The bottom uses a single layer of HDPE film for anti-seepage. When the water volume in the tank is large, the bottom anti-seepage membrane is difficult to maintain a flat state due to the gravity of the wastewater itself. When a depression occurs somewhere or is penetrated by a hard object, there is a risk of wastewater leakage and groundwater pollution; (2) The top uses a single layer of HDPE anti-seepage membrane for biogas collection. When the HDPE biogas collection membrane is not bulged by biogas, if there is rain, the rainwater will randomly form a large number of rainwater grooves on the HDPE membrane. These rainwater grooves will form uneven, bulging biogas storage spaces in the middle. Rainwater needs to be pumped out by a rainwater pump. Irregular biogas bags are difficult to collect into the surrounding biogas discharge pipes. At the same time, since black film biogas tanks are often large in area, it is very dangerous to manually remove the membrane and perform water pumping operations. (3) Poor insulation effect: Since the cross-sectional area of ​​the black film biogas anaerobic tank is often large, the use of a single-layer HDPE membrane for biogas collection can easily cause a significant drop in the wastewater temperature in the anaerobic reactor. This is also a common problem with black film biogas in China, resulting in low treatment effects in the black film biogas anaerobic tank, especially in winter conditions, where the anaerobic treatment effect is even lower.

[0004] For anaerobic reactors with larger cross-sectional areas (including low-load anaerobic reactors and black-film biogas anaerobic tanks), the present invention provides a floating membrane cover device with good thermal insulation effect, convenient rainwater collection and high safety, which can be used for biogas collection in such anaerobic reactors. Summary of the invention

[0005] The present invention provides a floating membrane cover device for collecting biogas, which solves the above problems.

[0006] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0007] The present invention discloses a floating membrane cover device for collecting biogas, which is arranged on the top of an anaerobic reactor. The floating membrane cover device comprises a floating membrane cover composed of an outer membrane cover, a middle heat-insulating interlayer, and an inner insulating film, a rainwater collection and return structure arranged on the floating membrane cover, a sampling port structure arranged on the floating membrane cover, a buoy structure installed on the floating membrane cover, and a fixed plastic pipe chain;

[0008] One end of the fixed plastic pipe chain is connected to the rainwater collection and return structure, and the other end is connected to the side wall of the anaerobic reactor or the buoy structure, so that the fixed plastic pipe chain is pressed down on the upper part of the floating membrane cover to form a rainwater drainage groove toward the rainwater collection and return structure;

[0009] The rainwater collection and return structure is used to drain the surrounding rainwater to the anaerobic reactor; the sampling port structure is used to collect the effluent of the anaerobic reactor and evaluate the treatment performance of the anaerobic reactor through detection; the buoy structure is used to raise the specific position height of the floating membrane cover, provide fixed support for the fixed plastic pipe chain in the middle of the floating membrane cover, and allow the rainwater to diffuse around the buoy structure into the rainwater drainage trough; a biogas collection and storage space is formed between the floating membrane cover and the internal liquid level of the anaerobic reactor and on the lower side of the connected position.

[0010] Furthermore, the rainwater collecting and returning structure includes a rainwater collecting and returning pipe that passes through the floating membrane cover, a first fixed flange that is arranged above the floating membrane cover, a second fixed flange that is arranged below the floating membrane cover, a rainwater collecting opening that is arranged at the top of the rainwater collecting and returning pipe, a second rainwater inlet that is arranged at the lower side of the rainwater collecting and returning pipe, a first inclined biogas baffle that is arranged at the bottom of the rainwater collecting and returning pipe, and an arc-shaped baffle that is arranged in the rainwater collecting and returning pipe and has a first rainwater inlet on its surface; the rainwater collecting and returning pipe is fixed to the floating membrane cover through the first fixed flange and the second fixed flange via first upper and lower fixing bolts.

[0011] Furthermore, the height between the bottom of the rainwater collection and return pipe and the bottom of the isolation membrane is 300 mm, and the height between the top of the rainwater collection and return pipe and the membrane cover is 20 mm; the first inclined biogas baffle is a closed plug with a 45-degree slope; the second rainwater inlet is a square water trough, and the height between the top of the second rainwater inlet and the bottom of the isolation membrane is 50 mm, and rainwater enters the anaerobic reactor through the second rainwater inlet or the first rainwater inlet.

[0012] Furthermore, the sampling port structure includes a sampling port tube that passes through the floating membrane cover, a third fixed flange plate that is arranged above the floating membrane cover, a fourth fixed flange plate that is arranged below the floating membrane cover, a sampling pipe port that is arranged above the sampling port tube, a wastewater inlet that is arranged at the lower side of the sampling port tube, a second inclined biogas baffle that is arranged at the bottom of the sampling port tube, and a waterproof cap that is installed on the top of the sampling port tube by transverse bolts; the sampling port tube is fixed to the floating membrane cover by the third fixed flange plate and the fourth fixed flange plate via second upper and lower fixing bolts.

[0013] Furthermore, the sampling tube mouth is 200mm away from the floating membrane cover, and the sampling port tube is 300mm below the isolation membrane; the second inclined biogas baffle is a closed plug with a 45-degree slope; the wastewater inlet is a square water trough, and the height between the top of the wastewater inlet and the bottom of the isolation membrane is 50mm.

[0014] Furthermore, the float structure includes a hard plastic foam disc body arranged between the membrane cover and the insulating membrane, a stainless steel fixed disc arranged on the outer surface of the membrane cover, and bolts that penetrate the stainless steel fixed disc and the membrane cover and are connected to bolt holes on the surface of the hard plastic foam disc body; the bottom of the hard plastic foam disc body is bonded and fixed to the insulating membrane; and a fixing ring connected to a fixed plastic pipe chain is welded on the stainless steel fixed disc.

[0015] Furthermore, the fixed shaping pipe chain is formed by connecting a number of UPVC ballast pipes via nylon ropes. The UPVC ballast pipes are filled with concrete. Caps are provided on both sides of the pipes. Two adjacent UPVC ballast pipes are connected via nylon ropes via connecting rings on the caps.

[0016] Furthermore, the membrane cover is a high-strength UV-resistant ethylene copolymer blend (EIA) fabric membrane material.

[0017] Furthermore, the heat insulating interlayer of the middle layer is an EPE pearl cotton heat insulating interlayer.

[0018] Furthermore, the inner insulating film is a HEPE anti-seepage film with a thickness of 2 mm.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. A floating membrane cover device for collecting biogas of the present invention adopts a high-strength, UV-resistant ethylene copolymer mixture (EIA) fabric membrane material. Compared with the HDPE anti-seepage membrane, the membrane material has the outstanding advantages of high UV resistance, high strength, high puncture resistance, high airtightness and good bonding performance. It has obvious advantages as the outer membrane of the floating membrane cover; at the same time, since the membrane cover of this material has high strength, the operator can safely perform related operations on the membrane cover, such as sampling.

[0021] 2. The inner membrane of the present invention adopts a conventional HDPE anti-seepage membrane, which contacts wastewater and has good sealing, heat preservation and anti-corrosion effects. A HEPE anti-seepage membrane with a thickness of 2 mm is conventionally used.

[0022] 3. The EPE pearl cotton heat insulation interlayer of the present invention is located between the outer film and the inner film and bonded to the inner film as a whole, which plays an important role in preventing heat loss in the anaerobic reactor. It is very important to ensure the reaction temperature in the anaerobic reactor. However, this type of interlayer is rarely used in China. Under conventional design conditions, a 12-20 mm thick pearl cotton foam interlayer is used.

[0023] 4. The floating membrane cover of the present invention is provided with a specially designed rainwater collection and return device that can prevent biogas leakage. The rainwater above the membrane cover is collected to multiple rainwater collection and return ports through a fixed plastic weight pipe chain, and flows into the anaerobic reactor, which can effectively prevent the rainwater from forming irregular grooves above the membrane cover, and there is no need to use a rainwater pump to suck the rainwater, which is simple and safe to operate;

[0024] 5. The sampling port provided on the floating membrane cover of the present invention can also facilitate the sampling and measurement of wastewater and sludge in the anaerobic reactor, which is impossible for the existing conventional black film biogas digester anaerobic reactor.

[0025] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0027] Figure 1 It is a structural schematic diagram of a floating membrane cover device for collecting biogas according to the present invention;

[0028] Figure 2 For the present invention Figure 1 Schematic diagram of the layer structure of the floating membrane cover;

[0029] Figure 3 This is a diagram of the installation of a floating membrane cover of a square anaerobic reactor according to Example 1 of the present invention;

[0030] Figure 4 This is a diagram of the installation of a floating membrane cover of a rectangular anaerobic reactor according to Example 2 of the present invention;

[0031] Figure 5 This is a diagram of the installation of a floating membrane cover of a circular anaerobic reactor according to Example 3 of the present invention;

[0032] Figure 6 A diagram showing the structure and installation relationship between the rainwater collection and return structure and the floating membrane cover of the present invention;

[0033] Figure 7 for Figure 6 The left view of the structure;

[0034] Figure 8 A top view of the rainwater collection and return structure of the present invention;

[0035] Fig. 9 A diagram showing the structure and installation relationship between the sampling port and the floating membrane cover of the present invention;

[0036] Fig.10 for Fig. 9 The left view of the structure;

[0037] Fig.11 A diagram showing the structure and installation relationship between the buoy structure and the floating membrane cover of the present invention;

[0038] Fig.12 This is the structural diagram of the existing black film biogas digester used to treat pig farm wastewater;

[0039] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0040] 1- anaerobic reactor, 101- biogas collection and storage space, 2- internal liquid level, 3- buoy structure, 301- hard plastic foam disc body, 302- stainless steel fixed disc, 303- bolt, 304- bolt hole, 305- fixed ring, 4- membrane cover, 5- heat insulation interlayer, 6- isolation membrane, 7- fixed plastic pipe chain, 8- rainwater collection and return structure, 801- rainwater collection and return pipe, 802- first fixed flange, 803- second fixed flange, 804- rainwater collection Opening, 805-first inclined biogas baffle, 806-arc-shaped baffle, 807-first rainwater inlet, 808-second rainwater inlet, 809-first upper and lower fixing bolts, 9-sampling port structure, 901-sampling port tube, 902-third fixing flange, 903-fourth fixing flange, 904-sampling tube mouth, 905-second inclined biogas baffle, 906-wastewater inlet, 907-waterproof cap, 908-transverse bolts, 909-second upper and lower fixing bolts, 10-floating membrane cover. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In the description of the present invention, it is necessary to understand that the terms "top", "outer layer", "middle layer", "one end", "side wall", "upper part" and the like indicate orientation or positional relationship, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0043] The common black film biogas digester pig wastewater anaerobic treatment storage tanks are as follows Fig.12 As shown, its structure specifically includes wastewater 31 in the black film biogas tank, slope 32 of the black film biogas tank, liquid level 33 in the black film biogas tank, shape 34 of the HDPE sealed film cover when the biogas reserve is small, shape 35 of the HDPE sealed film cover bulged by biogas when the biogas reserve is large, local rainwater collection groove 36 caused by the influence of heavy objects (mainly rainwater) on the HDPE sealed biogas film cover, and local biogas convex groove 37 caused by the influence of heavy objects (mainly rainwater) on the HDPE sealed biogas film cover;

[0044] The black film biogas digester is usually in the form of a sloped "earth pit", that is, a Fig.12 A pit of the shape shown in the figure is provided with an HDPE anti-seepage membrane at the bottom and on the slope, and a wastewater inlet pipe and wastewater and sludge discharge pipes are arranged through the pit. A single-layer HDPE anti-seepage membrane is used on the upper part of the wastewater and bonded to the bottom anti-seepage membrane laid on the slope to form an internal biogas storage space, which can be discharged or utilized through a biogas discharge pipe. Although this type of black film biogas anaerobic tank has a simple structure and low cost, it has the following obvious disadvantages: (1) The bottom uses a single layer of HDPE film for anti-seepage. When the water volume in the tank is large, the bottom anti-seepage membrane is difficult to maintain a flat state due to the gravity of the wastewater itself. When a depression occurs somewhere or is penetrated by a hard object, there is a risk of wastewater leakage and groundwater pollution; (2) The top uses a single layer of HDPE anti-seepage membrane for biogas collection. When the HDPE biogas collection membrane is not bulged by biogas, if there is rain, the rainwater will randomly form a large number of rainwater grooves on the HDPE membrane. These rainwater grooves will form uneven, bulging biogas storage spaces in the middle. Rainwater needs to be pumped out by a rainwater pump. Irregular biogas bags are difficult to collect into the surrounding biogas discharge pipes. At the same time, since black film biogas tanks are often large in area, it is very dangerous to manually remove the membrane and perform water pumping operations. (3) Poor insulation effect: Since the cross-sectional area of ​​the black film biogas anaerobic tank is often large, the use of a single-layer HDPE membrane for biogas collection can easily cause a significant drop in the wastewater temperature in the anaerobic reactor. This is also a common problem with black film biogas in China, resulting in low treatment effects in the black film biogas anaerobic tank, especially in winter conditions, where the anaerobic treatment effect is even lower.

[0045] For anaerobic reactors with larger cross-sectional areas (including low-load anaerobic reactors and black-film biogas anaerobic tanks), the present invention provides a floating membrane cover system and device with good thermal insulation effect, convenient rainwater collection and high safety, which can be used for biogas collection in such anaerobic reactors. The specific scheme is as follows. Specific embodiment 1:

[0047] See also Figure 1-3 As shown in Figures 6-11, a floating membrane cover device for collecting biogas of the present invention is provided on the top of an anaerobic reactor 1, the floating membrane cover device includes a floating membrane cover 10 composed of an outer membrane cover 4, a middle layer of heat insulation interlayer 5, and an inner layer of isolation film 6, a rainwater collection and fallback structure 8 provided on the floating membrane cover 10, a sampling port structure 9 provided on the floating membrane cover 10, a buoy structure 3 installed on the floating membrane cover 10, and a fixed molding pipe chain 7; the surrounding of the floating membrane cover 10 is bonded, sealed and fixed to the inner wall of the anaerobic reactor 1 by angle steel and adhesive;

[0048] One end of the fixed plastic pipe chain 7 is connected to the rainwater collection and return structure 8, and the other end is connected to the side wall of the anaerobic reactor 1 or the buoy structure 3, so that the fixed plastic pipe chain 7 is pressed down on the upper part of the floating membrane cover 10 to form a rainwater drainage groove toward the rainwater collection and return structure 8;

[0049] The rainwater collection and return structure 8 is used to drain the surrounding rainwater to the anaerobic reactor 1; the sampling port structure 9 is used to collect the effluent of the anaerobic reactor 1 and evaluate the treatment performance of the anaerobic reactor 1 through detection; the buoy structure 3 is used to raise the height of a specific position of the floating membrane cover 10, provide fixed support for the fixed plastic pipe chain 7 in the middle of the floating membrane cover 10, and allow the rainwater to diffuse around the buoy structure 3 into the rainwater drainage trough; a biogas collection and storage space 101 is formed between the floating membrane cover 10 and the internal liquid level 2 of the anaerobic reactor 1 and on the lower side of the connected position.

[0050] Among them, the rainwater collection and return structure 8 includes a rainwater collection and return pipe 801 arranged through the floating membrane cover 10, a first fixed flange 802 arranged above the floating membrane cover 10, a second fixed flange 803 arranged below the floating membrane cover 10, a rainwater collection opening 804 arranged at the top of the rainwater collection and return pipe 801, a second rainwater inlet 808 arranged at the lower side of the rainwater collection and return pipe 801, a first inclined biogas baffle 805 arranged at the bottom of the rainwater collection and return pipe 801, and an arc baffle 806 arranged in the rainwater collection and return pipe 801 and having a first rainwater inlet 807 on the surface; the rainwater collection and return pipe 801 is fixed to the floating membrane cover 10 through the first fixed flange 802 and the second fixed flange 803 via the first upper and lower fixing bolts 809.

[0051] Among them, the height between the bottom of the rainwater collection and return pipe 801 and the bottom of the isolation membrane 6 is 300 mm, and the height between the top of the rainwater collection and return pipe 801 and the membrane cover 4 is 20 mm; the first inclined biogas baffle 805 is a closed plug with a 45-degree slope; the second rainwater inlet 808 is a square water trough, and the height between the top of the second rainwater inlet 808 and the bottom of the isolation membrane 6 is 50 mm. Rainwater enters the anaerobic reactor 1 through the second rainwater inlet 808 or the first rainwater inlet 807.

[0052] Among them, the sampling port structure 9 includes a sampling port tube 901 that passes through the floating membrane cover 10, a third fixed flange 902 arranged above the floating membrane cover 10, a fourth fixed flange 903 arranged below the floating membrane cover 10, a sampling pipe port 904 arranged above the sampling port tube 901, a wastewater inlet 906 arranged at the lower side of the sampling port tube 901, a second inclined biogas baffle 905 arranged at the bottom of the sampling port tube 901, and a waterproof cap 907 installed on the top of the sampling port tube 901 through a transverse bolt 908; the sampling port tube 901 is fixed to the floating membrane cover 10 through the third fixed flange 902 and the fourth fixed flange 903 via the second upper and lower fixing bolts 909.

[0053] The sampling port pipe 901 has a diameter of DN200, a height above water (above the outer membrane of the membrane cover) of 200mm, and a depth below water (below the inner membrane of the membrane cover) of 300mm. The sampling port device is fixed on the floating membrane cover through the flange on the inner membrane side and the flange on the outer membrane side. The bottom of the sampling port device is a closed plug with a 45-degree slope. The upper part of the plug is located on the underwater tube with a square water groove with a width of 60mm. The top of the water groove is 50mm above the inner membrane. The biogas generated at the lower part of the sampling port in the anaerobic reactor 1 will be led to the surroundings of the underwater part of the sampling tube by the inclined plug and rise to the bottom of the inner membrane of the floating membrane cover. Since the top of the water trough is 50 mm away from the inner membrane, the rising biogas will not overflow from the water trough, but will diffuse to the surroundings of the reactor and gather in the biogas storage chamber around the anaerobic reactor; the second inclined biogas baffle 905 is a closed plug with a 45-degree inclined surface; the wastewater inlet 906 is a square water trough, and the height between the top of the wastewater inlet 906 and the bottom of the isolation membrane 6 is 50 mm; the sampling port tube 901 can directly collect the wastewater in the tube (that is, the effluent of the anaerobic reactor) to evaluate the treatment performance of the anaerobic reactor through testing. At the same time, a dedicated sludge sampling tube can be used to pass through the water trough and penetrate into the interior of the anaerobic reactor to collect the anaerobic sludge concentration at different heights inside the anaerobic reactor, thereby calculating the overall sludge amount in the anaerobic reactor to evaluate whether the treatment capacity of the anaerobic reactor meets the requirements of the total amount of influent pollutants.

[0054] Among them, the buoy structure 3 includes a hard plastic foam disc body 301 arranged between the membrane cover 4 and the insulating membrane 6, a stainless steel fixed disc 302 arranged on the outer surface of the membrane cover 4, and a bolt 303 that penetrates the stainless steel fixed disc 302 and the membrane cover 4 and is connected to a bolt hole 304 on the surface of the hard plastic foam disc body 301; the bottom of the hard plastic foam disc body 301 is bonded and fixed to the insulating membrane 6; a fixing ring 305 connected to the fixed plastic pipe chain 7 is welded on the stainless steel fixed disc 302; the diameter of the hard plastic foam disc body 301 is generally 1.5 to 2 mm in diameter and 300 to 500 mm in height.

[0055] Among them, the fixed shaping pipe chain 7 is formed by a number of UPVC ballast pipes connected by nylon ropes. The UPVC ballast pipes are filled with concrete, and caps are provided on both sides of the pipes. The adjacent two UPVC ballast pipes are connected by nylon ropes through the connecting rings on the caps.

[0056] Among them, the membrane cover 4 is a high-strength, UV-resistant XR-5 material, and the outer membrane is an ethylene copolymer mixture (EIA) fabric membrane produced by SEAMAN, USA; compared with the HDPE anti-seepage membrane, this membrane material has the outstanding advantages of high UV resistance, high strength, high puncture resistance, high airtightness, and good bonding performance. It has obvious advantages as the outer membrane of a floating membrane cover; at the same time, since the membrane cover of this material is very strong, the operator can safely perform related operations (such as sampling, etc.) on the membrane cover.

[0057] Among them, the heat-insulating interlayer 5 of the middle layer is an EPE pearl cotton heat-insulating interlayer; it plays an important role in preventing heat loss in the anaerobic reactor, and is very important for ensuring the reaction temperature in the anaerobic reactor. However, this type of interlayer is rarely used in China, and a 12-20 mm thick pearl cotton foam interlayer is used under conventional design conditions. According to the different sizes of the pool walls or tank walls of different projects, the inner membrane and the middle heat-insulating interlayer are pre-spliced ​​and bonded into a whole in the factory, the outer membrane is a separate layer, and the three layers of membrane are rolled into a whole for on-site installation. If it is a design with a float, the float needs to be pre-fixed in the designed position. During installation, the integrated membrane cover is unfolded on the water surface, and the periphery of the membrane cover is fixed to the pool wall or tank wall.

[0058] The inner insulating film 6 is a 2mm thick HEPE anti-seepage film, which contacts the wastewater and has good sealing, heat preservation and anti-corrosion effects;

[0059] The anaerobic reactor 1 adopts a square anaerobic reactor, the floating membrane cover 10 adopts a square structure corresponding to the square anaerobic reactor, the buoy structure 3 is arranged in the middle position, and the sampling port structures 9 are symmetrically arranged on both sides of the buoy structure 3; rainwater collection and return structures 8 are respectively arranged above and below the sampling port structure 9, and the rainwater collection and return structures 8 are connected to the side wall of the anaerobic reactor 1 and the buoy structure 3 through fixed plastic pipe chains 7;

[0060] The design quantity of the rainwater collection and return structure 8 varies according to the size and shape of the anaerobic reactor 1. For a conventional square or circular reactor, a buoy is set in the middle, and the number of rainwater collection ports is set to 4. The positions of the 4 rainwater ports are located between the buoy and the pool wall, and are located at 1 / 3 of the distance from the buoy. After the rainwater collection and return device is installed, the fixed plastic pipe chain 7 is connected to the buoy structure 3 along the pipe chain angle of 120 degrees, and the other two counterweight pipe chains are fixed on the pool wall or tank wall. Under the weight of the counterweight pipe chain, the fixed plastic pipe chain 7 on the upper edge of the floating membrane cover will form a concave groove that can flow rainwater, and the surrounding rainwater will be drained to the rainwater port and flow into the anaerobic reactor 1.

[0061] The number and installation location of the sampling port structures 9 are not fixed. The sampling port device can be installed at the location where monitoring and sampling are required according to the different designs of the anaerobic reactor 1. If there is no need to sample at the top, the sampling port device can be installed. The fixed plastic pipe chain 7 is placed on the membrane cover to form a rainwater drainage groove on the membrane cover by its weight. At the same time, it is used for the problem of large weight and can also prevent the membrane cover system from being bulged by biogas. At the same time, it is conducive to the diffusion of biogas under the membrane cover along the membrane cover to the pool wall or tank wall. Specific embodiment 2:

[0063] The difference between this specific embodiment and specific embodiment 1 is that:

[0064] The anaerobic reactor 1 adopts a rectangular anaerobic reactor, and the floating membrane cover 10 adopts a rectangular structure corresponding to the rectangular anaerobic reactor. A rainwater collection and return structure 8 and a sampling port structure 9 are arranged between the two inner walls of the anaerobic reactor 1. The rainwater collection and return structure 8 is connected to the two side walls of the rectangular anaerobic reactor through a fixed plastic pipe chain 7; because under the conditions of the rectangular anaerobic reactor, the plastic fixed counterweight pipe chain is arranged in the anaerobic width direction, it is usually not necessary to set a buoy, but the rainwater collection port is designed to a certain position on the straight pipe chain, so that the rainwater can be drained into the anaerobic reactor; the function of the buoy structure 3 is to raise the height of the floating membrane cover at a certain position in the anaerobic reactor, provide fixed support for the fixed plastic pipe chain 7 in the middle of the membrane cover, and enable the rainwater to diffuse around the buoy instead of forming a groove. Specific embodiment 3:

[0066] The difference between this specific embodiment and specific embodiment 1 is that:

[0067] The anaerobic reactor 1 adopts a circular anaerobic reactor, and the floating membrane cover 10 adopts a circular structure corresponding to the circular anaerobic reactor. The buoy structure 3 is arranged in the middle position, and a rainwater collection and return structure 8 and a sampling port structure 9 are arranged around the buoy structure 3; the rainwater collection and return structure 8 is connected to the side wall of the circular anaerobic reactor and the buoy structure 3 through a fixed plastic pipe chain 7.

[0068] The implementation steps of this technical solution are:

[0069] Under normal conditions, as the biogas collection membrane cover at the top of the anaerobic reactor, the liquid level in the anaerobic reactor is a constant value, and the liquid level in the anaerobic reactor maintains a height difference of 0.5 to 1m with the pool wall or tank wall around the reactor. After the combined floating membrane cover system is connected, sealed, and fixed around the reactor pool wall or tank wall, except for the membrane cover system and the anaerobic reactor pool wall or tank wall around the periphery, which will form a certain space, the rest of the membrane cover system will float on the liquid surface of the anaerobic reactor. Due to the buoyancy of the liquid, the membrane cover can withstand a certain pressure, which is convenient for operators or installers to operate on the membrane cover. Depending on the use scenario, it can be decided whether it is necessary to set an intermediate buoy on the floating membrane cover system to facilitate rainwater drainage. The diameter of the buoy is generally 1.5m to 2m, which needs to be pre-positioned and bonded to the HDPE membrane. The upper part of the buoy can be fixed to the outer membrane with a stainless steel disc with a handle by bolts.

[0070] After the membrane cover is fixed, the rainwater collection and return device can be installed according to the set rainwater drainage port position. The device is made of stainless steel SS216L and has a pipe diameter of 200mm. Then the fixed plastic counterweight pipe chain is arranged in three directions along the rainwater collection and return device to the outside and fixed at the set position. Concrete is filled in the counterweight pipe. Under the action of the fixed plastic counterweight pipe chain, the rainwater collected on the floating membrane cover will be drained to each rainwater collection and return port, and fall back to the inside of the anaerobic reactor, thereby avoiding the problem of rainwater gathering on the membrane cover and needing to be pumped by a pump. At the same time, a sampling port is set on the floating membrane cover system where the wastewater and sludge in the anaerobic reactor need to be collected. After the sampling is completed, the upper waterproof cap needs to be tightly closed to prevent rainwater and debris from entering and exhaust gas from overflowing.

[0071] The anaerobic reactor using the floating membrane cover system and device will have the biogas produced directed to the space around the anaerobic reactor, namely, the biogas collection and storage space 101. The biogas in the biogas collection and storage space 101 is extracted by an external biogas fan for processing or utilization, so that the biogas pressure in the biogas storage chamber maintains a certain negative pressure condition. A pressure sensor is provided in the biogas storage chamber, and the set pressure range is usually -300Pa to +20Pa. The biogas is extracted by a variable frequency biogas suction fan. Under normal operating conditions, the pressure in the biogas storage chamber is maintained at -80Pa to 0Pa. When the pressure in the biogas storage chamber is lower than -300Pa, the biogas suction fan needs to be turned off. When the pressure in the biogas storage chamber exceeds 20Pa, the biogas suction capacity needs to be increased by frequency conversion or the standby fan needs to be started to increase the biogas suction capacity.

[0072] This new type of floating biogas collection membrane cover system and device can not only effectively collect biogas generated by the anaerobic system, but also make the maintenance of the anaerobic reactor simpler. The membrane cover can be easily removed to repair and maintain the internal components of the anaerobic reactor (such as the three-phase separator, etc.), and the service life is long. By adding a biogas drainage trough design, it can also be used for biogas collection in anaerobic reactors with constantly changing liquid levels, such as biogas collection in black film biogas anaerobic tanks, and has broad application prospects.

[0073] Beneficial effects:

[0074] 1. A floating membrane cover device for collecting biogas of the present invention adopts a high-strength, UV-resistant ethylene copolymer mixture (EIA) fabric membrane material. Compared with the HDPE anti-seepage membrane, the membrane material has the outstanding advantages of high UV resistance, high strength, high puncture resistance, high airtightness and good bonding performance. It has obvious advantages as the outer membrane of the floating membrane cover; at the same time, since the membrane cover of this material has high strength, the operator can safely perform related operations on the membrane cover, such as sampling.

[0075] 2. The inner membrane of the present invention adopts a conventional HDPE anti-seepage membrane, which contacts wastewater and has good sealing, heat preservation and anti-corrosion effects. A HEPE anti-seepage membrane with a thickness of 2 mm is conventionally used.

[0076] 3. The EPE pearl cotton heat insulation interlayer of the present invention is located between the outer film and the inner film and bonded to the inner film as a whole, which plays an important role in preventing heat loss in the anaerobic reactor. It is very important to ensure the reaction temperature in the anaerobic reactor. However, this type of interlayer is rarely used in China. Under conventional design conditions, a 12-20 mm thick pearl cotton foam interlayer is used.

[0077] 4. The floating membrane cover of the present invention is provided with a specially designed rainwater collection and return device that can prevent biogas leakage. The rainwater above the membrane cover is collected to multiple rainwater collection and return ports through a fixed plastic weight pipe chain, and flows into the anaerobic reactor, which can effectively prevent the rainwater from forming irregular grooves above the membrane cover, and there is no need to use a rainwater pump to suck the rainwater, which is simple and safe to operate;

[0078] 5. The sampling port provided on the floating membrane cover of the present invention can also facilitate the sampling and measurement of wastewater and sludge in the anaerobic reactor, which is impossible for the existing conventional black film biogas digester anaerobic reactor.

[0079] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A floating membrane cover device for collecting biogas, arranged on the top of an anaerobic reactor (1), characterized in that: The floating membrane cover device comprises a floating membrane cover (10) composed of an outer membrane cover (4), a middle heat-insulating interlayer (5), and an inner insulating film (6), a rainwater collection and return structure (8) arranged on the floating membrane cover (10), a sampling port structure (9) arranged on the floating membrane cover (10), a buoy structure (3) installed on the floating membrane cover (10), and a fixed plastic pipe chain (7); One end of the fixed plastic pipe chain (7) is connected to the rainwater collection and return structure (8), and the other end is connected to the side wall of the anaerobic reactor (1) or the buoy structure (3), so that the fixed plastic pipe chain (7) is pressed down on the upper part of the floating membrane cover (10) to form a rainwater drainage groove toward the rainwater collection and return structure (8); The rainwater collection and return structure (8) is used to drain the surrounding rainwater to the anaerobic reactor (1); the sampling port structure (9) is used to collect the effluent of the anaerobic reactor (1) and evaluate the treatment performance of the anaerobic reactor (1) through testing; the buoy structure (3) is used to raise the height of a specific position of the floating membrane cover (10), provide fixed support for the fixed plastic pipe chain (7) in the middle of the floating membrane cover (10), and allow the rainwater to diffuse around the buoy structure (3) and enter the rainwater drainage trough; a biogas collection and storage space (101) is formed between the floating membrane cover (10) and the internal liquid level (2) of the anaerobic reactor (1) and on the lower side of the connected position; The rainwater collection and return structure (8) comprises a rainwater collection and return pipe (801) penetrating the floating membrane cover (10), a first fixed flange (802) arranged above the floating membrane cover (10), a second fixed flange (803) arranged below the floating membrane cover (10), a rainwater collection opening (804) arranged at the top of the rainwater collection and return pipe (801), a second rainwater inlet (808) arranged at the lower side of the rainwater collection and return pipe (801), a first inclined biogas baffle (805) arranged at the bottom of the rainwater collection and return pipe (801), and an arc-shaped baffle (806) arranged in the rainwater collection and return pipe (801) and having a first rainwater inlet (807) on its surface; the rainwater collection and return pipe (801) is fixed to the floating membrane cover (10) through the first fixed flange (802) and the second fixed flange (803) via first upper and lower fixing bolts (809); The sampling port structure (9) comprises a sampling port pipe (901) penetrating the floating membrane cover (10), a third fixed flange (902) arranged above the floating membrane cover (10), a fourth fixed flange (903) arranged below the floating membrane cover (10), a sampling pipe port (904) arranged above the sampling port pipe (901), a wastewater inlet (906) arranged at the lower side of the sampling port pipe (901), a second inclined biogas baffle (905) arranged at the bottom of the sampling port pipe (901), and a waterproof cap (907) installed on the top of the sampling port pipe (901) via transverse bolts (908); the sampling port pipe (901) is fixed to the floating membrane cover (10) via the third fixed flange (902) and the fourth fixed flange (903) via second upper and lower fixing bolts (909); The sampling pipe port (904) is 200 mm away from the floating membrane cover (10), and the sampling port pipe (901) is 300 mm below the isolation membrane (6); the second inclined biogas baffle (905) is a closed plug with a 45-degree inclined surface; the wastewater inlet (906) is a square water trough, and the height between the top of the wastewater inlet (906) and the bottom of the isolation membrane (6) is 50 mm; The buoy structure (3) comprises a hard plastic foam disc body (301) arranged between the membrane cover (4) and the insulating membrane (6), a stainless steel fixed disc (302) arranged on the outer surface of the membrane cover (4), and a bolt (303) penetrating the stainless steel fixed disc (302) and the membrane cover (4) and connected to a bolt hole (304) on the surface of the hard plastic foam disc body (301); the bottom of the hard plastic foam disc body (301) is bonded and fixed to the insulating membrane (6); a fixing ring (305) connected to a fixed plastic pipe chain (7) is welded on the stainless steel fixed disc (302); The fixed shaping pipe chain (7) is formed by connecting a plurality of UPVC weight pipes via nylon ropes. The UPVC weight pipes are filled with concrete. Caps are provided on both sides of the pipes. Two adjacent UPVC weight pipes are connected via nylon ropes via connecting rings on the caps.

2. A floating membrane cover device for collecting biogas according to claim 1, characterized in that: The height between the bottom of the rainwater collection and return pipe (801) and the bottom of the isolation membrane (6) is 300 mm, and the height between the top of the rainwater collection and return pipe (801) and the membrane cover (4) is 20 mm; the first inclined biogas baffle (805) is a closed plug with a 45-degree inclined surface; the second rainwater inlet (808) is a square water trough, and the height between the top of the second rainwater inlet (808) and the bottom of the isolation membrane (6) is 50 mm. Rainwater enters the anaerobic reactor (1) through the second rainwater inlet (808) or the first rainwater inlet (807).

3. A floating membrane cover device for collecting biogas according to claim 1, characterized in that: The membrane cover (4) is a high-strength UV-resistant ethylene copolymer mixture (EIA) fabric membrane material.

4. A floating membrane cover device for collecting biogas according to claim 1, characterized in that: The heat insulating interlayer (5) of the middle layer is an EPE pearl cotton heat insulating interlayer.

5. A floating membrane cover device for collecting biogas according to claim 1, characterized in that: The inner insulating film (6) is a HEPE anti-seepage film with a thickness of 2 mm.

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