CN110184171A - A kind of mono- two-phase anaerobic digestion device of perishable organic matter - Google Patents

Abstract

The invention discloses a single-dual-phase dual-purpose anaerobic digestion device for perishable organic matter, which is aimed at the fluctuation of the amount of raw materials with time in the process of producing biogas from organic waste such as fruit and vegetable waste and cellulose hydrolyzate in the traditional anaerobic digestion device And easy acidification and other problems, and proposed a new type of anaerobic digestion device. The main body of the anaerobic digestion device includes a CSTR+UASB anaerobic digestion tank (1), a UASB anaerobic digestion tank (2), (1) (2) tank communication pipes (3) and upper valves (4) (5). Through the closing and opening of the valves (4) and (5), the series and parallel connection of the two tanks can be realized to achieve the purpose of single-phase or two-phase reaction.

Description

A single-two-phase anaerobic digestion device for perishable organic matter

technical field

The invention relates to a single-two-phase anaerobic digestion device aimed at producing biogas by anaerobic digestion of organic wastes such as fruit and vegetable wastes and cellulose hydrolyzates that are easily acidified and whose raw material sources have time fluctuations.

Background technique

Since the 1980s, the pollution of fruit and vegetable processing waste has been paid more and more attention, and domestic and foreign studies have begun to study the treatment and disposal methods specifically for agricultural fruit and vegetable processing waste. With the continuous deepening of research and the rapid development of anaerobic digestion technology, researchers gradually realized that anaerobic digestion technology is more suitable for the characteristics of high water content of fruit and vegetable processing waste, and can achieve relatively complete waste stabilization and energy recovery. , to reduce greenhouse gas emissions, and is a reasonable choice to deal with fruit and vegetable processing waste.

In terms of anaerobic digestion of fruit and vegetable waste, it was found that mixed fruit and vegetable waste with a solid content of 5% could be successfully operated in a batch anaerobic digestion system. Mata-Alvarez et al. used a single-phase completely mixed reactor (CSTR) to digest fruit and vegetable waste at mesophilic temperature, and its maximum organic load was lower than 3kg TVS/m ³ d, but the maximum organic load of other similar wastes could reach 6kg TVS/m ³ ·d, it is considered that the rapid generation of a large amount of volatile fatty acids limits the increase of organic load. At the same time, since fruit and vegetable harvests are affected by seasonal changes, biogas projects that use fruit and vegetable waste as raw materials should fully consider the time fluctuation of raw material sources to ensure that the raw materials of fruit and vegetable waste can be fully consumed while fully utilizing the engineering equipment. efficiency and reduce engineering investment.

In terms of anaerobic digestion of fruit and vegetable processing waste, patent 201010241842.8 mainly describes the technologies of raw material pretreatment and fermentation inoculum for biogas production from fruit and vegetable waste, and also indicates that the patented technology is only applicable to small anaerobic digesters of 6-100 cubic meters. Fermentation device. Patent 200710046930.0 also only studies the technology of anaerobic fermentation of vegetable waste to prepare biogas, but does not study the device. Patent 201010106904.4 discloses a method for producing biogas by anaerobic digestion of perishable organic waste with high solids in two phases and three stages. The method uses two-phase anaerobic digestion of perishable waste to produce biogas. The digestion device obtained is only a simple experimental device in the laboratory, which is far from the engineering application device. Patent 200810064362.1 discloses a device and method for biogas production from fruit and vegetable waste. The patent studies the process parameters in the two-phase fermentation process, but the device is only an experimental device, and it is difficult to guide engineering production. Patent 201210180850.5 discloses a method for anaerobic digestion of fruit and vegetable waste to produce biogas. This method uses extrusion to separate the raw materials of fruits and vegetables, and then strengthens the acid production of liquid and solid products, and then enters the methanogenic phase to realize two-phase fermentation. , but only a 5L primary hydrolysis acidification reactor, a 2L solid residue secondary enhanced hydrolysis acidification reactor, a 5L leachate collection tank, and a 2L methanation reactor were tested. Patent 201210448062.X discloses a two-stage solid-liquid two-phase anaerobic fermentation cycle system and a biogas production method. The method ensures stable methane production with high solid concentration by circulating the liquid. Similar patents include 200810104975, etc., but most of the existing patents only focus on the research on related technologies of two-phase fermentation, including raw material pretreatment, inoculum and inoculum volume, etc., but it is very difficult for engineering equipment that can be applied to practical applications. few.

Contents of the invention

The present invention aims at the anaerobic digestion research process of easily acidified organic wastes such as fruit and vegetable wastes and cellulose hydrolyzate. Due to the main focus on fermentation process research and the lack of corresponding engineering device development, fruit and vegetable wastes and other easily acidified organic wastes To solve the problem of slow development of biogas projects prepared by anaerobic digestion, a single-two-phase anaerobic digestion device is provided for organic wastes such as fruit and vegetable wastes that are easily acidified and whose raw material sources have time fluctuations.

During the two-phase reaction, the anaerobic digestion tank (1) is used as an enhanced acidification tank, which can ensure sufficient acidification of the raw materials and quickly produce a large amount of volatile organic acids. When the liquid rich in organic acids in the tank (1) enters the tank (2) , into the state of biogas production, avoiding the abnormal termination of the fermentation process caused by the inhibition of methanogenic bacteria by excessive acidification.

During the single-phase reaction, the anaerobic digestion tanks (1) and (2) are fed at the same time. Since the raw material concentration and organic load are controlled at this time, the UASB process can ensure the smooth progress of the anaerobic process and reduce energy consumption. consumption.

The technical solution adopted by the present invention to solve the above problems

1. The single-two-phase anaerobic digestion device includes CSTR+UASB or UASB dual-purpose anaerobic digestion tank (1), UASB anaerobic digestion tank (2), (1) (2) tank communication pipe (12) and The upper valves (4) and (5) are characterized in that the single-phase and dual-phase modes of the anaerobic digestion device are determined according to the concentration of raw materials in the adjustment tank, so as to realize the device's ability to efficiently process organic waste and produce biogas.

2. When the raw materials of easy-to-acidify organic waste such as fruit and vegetable waste are sufficient, adopt a two-phase reaction mode to increase the organic load of the anaerobic digestion tank (1), that is, close the valve (4) and valve (6), and open the valve (5 ), to realize the series connection of anaerobic digestion tank (1) and (2), the raw material is transported from the regulating tank to the anaerobic tank (1) through the pump (7), and the biogas slurry in the anaerobic digestion tank (2) is reused to reduce the The demand for tap water in the process of raw material conditioning, thereby reducing the production of biogas slurry in the fermentation process.

3. When the amount of easy-to-acidify organic waste such as fruit and vegetable waste is small, the single-phase reaction mode is adopted, and the anaerobic tank (1) (2) is connected in parallel, that is, the valve (5) is closed, and the valve (4) and ( 6), the raw material is transported from the regulating tank to the anaerobic tank (1) (2) respectively through the pump (13) (14), the valve (3) on the forced circulation pipe (8) is opened intermittently, and the biogas slurry is passed through the mouth (7) ) to reuse the biogas slurry to reduce the demand for tap water in the conditioning process of raw materials, thereby reducing the output of biogas slurry in the fermentation process.

4. When the series mode is used, in order to improve the digestibility of the digester (1) for high-load and high-concentration raw materials, the stirring (15) in the digester (1) is turned on, and the CSTR+UASB mode is adopted, while the digester (2 ) adopts the UASB mode; when adopting the parallel mode, due to the low concentration of raw materials in the adjustment tank, the digestion tanks (1) and (2) both adopt the UASB mode.

5. When the series mode is adopted, the raw materials entering the anaerobic digestion tank (1) (2) are evenly injected into the anaerobic digestion tank through the feed main pipe through the distributor (17).

6. There are three agitators (15) in the anaerobic digestion tank (1), which are at a height of 0.5-1.5 meters from the bottom of the tank. They are respectively arranged at an angle of 120° around the bottom of the tank body, and the motor shaft is at an angle of 30°. Ensure the full mixing of low and high concentration materials in the tank. Stirring runs intermittently, the motor is turned on every 2-6 hours, and runs for 30-90 minutes.

7. The anaerobic digestion tank (1) adopts two designs of CSTR and UASB. When the fermentation process adopts two-phase fermentation, the material concentration in the anaerobic digestion tank (1) is 10-15%, and at this time it is necessary to start stirring ( 15), to ensure uniform mass transfer of raw materials. The three-phase reactor on the upper side of the tank can separate the solids to ensure that the fermentation broth enters the anaerobic digestion tank (2) from the nozzle (11) through the pipe (12).

8. The anaerobic digestion tank (2) adopts UASB design, and the three-phase reactor on the upper side of the tank can further separate the solids, so as to reduce the content of solids in the biogas slurry eliminated by (7) as much as possible, and improve the yield of raw materials. Utilization rate, to avoid waste of raw materials.

9. The biogas outlet (16) at the top of the anaerobic digestion tank (1) (2) is communicated with the membrane gas holder through the main pipe to ensure that the internal pressure of the tank (1) (2) is the same.

10. The anaerobic digestion tanks (1) and (2) are connected to the regulating tank through the forced return pipe (8). The use of the forced return pipe ensures the consistency of the fermentation characteristics of the two anaerobic digestion tanks in parallel operation, which can Simplify the need to change the process of transferring feed liquid from the adjustment tank to the anaerobic tank each time due to the difference in the fermentation process of the two tanks.

11. The distributor (17) is connected to the gas storage tank, and the biogas in the gas storage tank is turned on every 1-5 days to purge the distributor for 30 minutes, so as to avoid blockage caused by material deposition in the distributor and affect the distribution effect of the material liquid.

Beneficial effects of the present invention

1. The present invention fully considers the time fluctuation of fruit and vegetable waste raw materials, and selects the anaerobic digestion process as single/double phase according to the raw materials. When the supply of raw materials is sufficient, in order to consume the raw materials as soon as possible, increase the concentration of the raw materials, and avoid acidification problems caused by too much load, a two-phase reaction is adopted. When the source of raw materials decreases, the parallel single-phase reaction is adopted to reduce the material concentration, which improves the utilization rate of the device, saves energy consumption and ensures the smooth progress of the biogas production process.

2. The anaerobic digestion tank (1) adopts the CSTR+UASB design process to ensure that when the solid concentration is high, the raw materials are fully mixed by stirring to improve the efficiency of the fermentation process, and the three-phase reactor can fully separate the solid and liquid, Improve the utilization rate of raw materials. In addition, when the concentration of the raw material is low, the UASB process can be selected separately without stirring, which reduces the energy consumption of the project operation.

3. The use of the forced reflux pipe ensures the consistency of the fermentation characteristics of the two anaerobic digestion tanks in parallel operation, which can simplify the need to change the feeding liquid from the adjustment tank to the anaerobic tank due to the difference in the fermentation process of the two tanks. the process of.

5. The device does not contain complex electrical components. On the one hand, it is easy to operate, and on the other hand, it avoids the damage of electrical components from affecting the fermentation process and ensures the stability of the project.

In addition, the present invention provides engineering equipment for the development of the fruit and vegetable waste production biogas industry, which makes up for the current lack of engineering equipment research in this field, will certainly promote the development of related industries, and solve the non-point source caused by fruit and vegetable waste. While reducing pollution, it also provides cheap biogas energy.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

In the figure (1) CSTR+UASB anaerobic digestion tank; (2) UASB anaerobic digestion tank; (3) forced circulation pipe valve; (4) valve; (5) valve; (6) valve; (7) biogas slurry (8) forced circulation pipe; (9) three-phase reactor; (10) biogas residue port; (11) tank (1) biogas slurry outlet; (12) tank (1) (2) connecting pipe; (13 ) feed pump; (14) feed pump; (15) CSTR stirring paddle; (16) biogas nozzle; (17) distributor.

Detailed ways

Example 1:

The biogas project of Boxing County Guofeng High-efficiency Circular Ecological Agriculture Development Co., Ltd., anaerobic digestion tanks (1) and (2) are both 1,000 cubic meter fermentation tanks. The park is the peak harvest season, and a large amount of fruit and vegetable waste is generated every day.

1. Cucumber seedlings, tomato seedlings and cabbage leaves are crushed by a beater, and the water content of the raw materials is adjusted in the adjustment tank according to the water content of the raw materials and supplemented with biogas slurry, so that the solid content of the raw materials is 12%.

2. Close the valve (4) and the valve (6), open the valve (5) to realize the series connection of the anaerobic digestion tank (1) and (2), and the raw material is transported from the adjustment tank to the anaerobic tank (13) via the pump (13) ).

3. The agitation in the anaerobic digestion tank (1) is started for 30 minutes every 4 hours.

3. Control the temperature of the anaerobic tank (1) (2) to be 35°C.

4. Adjust the residence period of raw materials in the anaerobic tank (1) to 4 days, the residence period in the anaerobic tank to 3 days, and the pH of the biogas slurry outlet to 6.8.

5. During the fermentation process, the average methane yield is 310ml CH ₄ /g-VS, the volumetric gas production rate is 1.7m ³ /(m ³ ·d), and the methane content is 65% (v/v).

Example 2:

The biogas project of Boxing County Guofeng High-efficiency Circular Ecological Agriculture Development Co., Ltd., anaerobic digestion tanks (1) and (2) are both 1,000 cubic meter fermentation tanks. The park is the peak harvest season, and a large amount of fruit and vegetable waste is generated every day.

1. Cucumber seedlings, tomato seedlings and cabbage leaves are crushed by a beater, and the water content of the raw materials is adjusted in the adjustment tank according to the water content of the raw materials and supplemented with biogas slurry, so that the solid content of the raw materials is 12%. Adjust the residence period of raw materials in the anaerobic tank (1) (2) to be 7 days.

2. The anaerobic tanks (1) (2) are connected in parallel, that is, the valve (5) is closed, the valves (4) and (6) are opened, and the raw materials are transported to the anaerobic tank from the regulating tank through the pump (13) (14) (1)(2).

3. Open and open the valve (3) on the forced circulation pipe (8) every 12 hours, so that the fermentation liquid of the anaerobic tank (1) (2) is fully mixed in the regulating tank to ensure the consistency of the fermentation process of the two tanks.

4. Control the temperature of the anaerobic tank (1) (2) to be 35°C.

5. During the first two days of the fermentation process, the average methane production rate was 187ml CH ₄ /g-VS, the volumetric gas production rate was 0.6m ³ /(m ³ ·d), and the methane content was 61% (v/v); After three days, the gas production decreased significantly, the methane content in the gas produced was only 1.9% (v/v), and the pH of the fermentation broth was 2.6, which indicated that acid accumulation occurred during the fermentation process, which led to the failure of the methane production process.

Example 3:

The biogas project of Boxing County Guofeng High-efficiency Circular Ecological Agriculture Development Co., Ltd., anaerobic digestion tanks (1) and (2) are both 1,000 cubic meter fermentation tanks. The park is in the off-season for harvesting, and a small amount of fruit and vegetable waste is generated every day.

1. Cucumber seedlings, tomato seedlings and cabbage leaves are crushed by a beater, and the water content of the raw materials is adjusted in the adjustment tank according to the water content of the raw materials and supplemented with biogas slurry, so that the solid content of the raw materials is 6%. The residence period of the raw materials in the anaerobic tanks (1) and (2) is adjusted to be 7 days, and the pH of the biogas slurry outlet is 6.9.

2-4, as embodiment 2;

5. During the fermentation process, the average methane yield was 296ml CH ₄ /g-VS, the volumetric gas production rate was 1.8m ³ /(m ³ ·d), and the methane content was 63% (v/v).

Embodiment 2 is identical with embodiment 3 technical process, all adopts parallel mode, and anaerobic tank (1) (2) is UASB process, difference is that the feed concentration in embodiment 2 is 12%, and in embodiment 3 is 6 %. Different from the normal operation of Example 3, in Example 2, because the feed concentration was too high, acidification occurred during the fermentation process, and the fermentation failed.

Further analysis, because the anaerobic tank (1) (2) is connected in series in embodiment 1, the residence time of material in two tanks is respectively 7 days, so be equivalent to the residence time of material in the whole anaerobic process be 14 days; Although embodiment 3 feed concentration has only 50% of embodiment 1, because anaerobic tank (1) (2) starts in parallel, residence time is 7 days, so final embodiment 3 and embodiment 1 are to the handling capacity of substrate Are the same.

The (1) tank in Example 1 adopts the CSTR process. The advantage is that when there are a large amount of raw materials, high-concentration raw materials can be quickly put into the fermenter to avoid the environmental impact caused by the accumulation of raw materials in the park, but the fermentation process requires mechanical stirring of the materials; Therefore, when the material handling pressure is not high, adopting the process of Example 3 in time will reduce the energy consumption of the process and improve the project benefit. Therefore, according to the amount of waste in the production process of the park, by connecting the anaerobic tanks (1) (2) in series and in parallel, the operation efficiency and benefits of the project can be improved while ensuring timely disposal of waste.

Claims (7)

1. A single-two-phase anaerobic digestion device for perishable organic matter, including CSTR+UASB or UASB dual-purpose anaerobic digestion tank (1), UASB anaerobic digestion tank (2), (1) (2) tank communication pipe (12) and its upper valves (4) (5), characterized in that: the single-phase and dual-phase modes of the anaerobic digestion device are determined according to the concentration of the raw materials in the adjustment tank, so as to realize the high-efficiency treatment of organic waste and the ability of the device to produce biogas . 2. A single-two-phase anaerobic digestion device for perishable organic matter according to claim 1, characterized in that: when the raw materials of easily acidified organic waste such as fruit and vegetable waste are sufficient, a two-phase reaction mode is adopted to improve anaerobic digestion. The organic load of the digestion tank (1) is to close the valve (4) and the valve (6), open the valve (5), and realize the series connection of the anaerobic digestion tank (1) and (2), and the raw material is sent from the regulating tank through the pump (13 ) to the anaerobic tank (1), through the reuse of the biogas slurry in the anaerobic digestion tank (2), the demand for tap water in the raw material conditioning process is reduced, thereby reducing the biogas slurry output during the fermentation process. 3. A single-two-phase anaerobic digestion device for perishable organic matter according to claim 1, characterized in that: when the amount of easy-to-acidify organic waste such as fruit and vegetable waste and cellulose hydrolyzate is small, single-phase In the reaction mode, the anaerobic tanks (1) (2) are connected in parallel, that is, the valve (5) is closed, the valves (4) and (6) are opened, and the raw materials are transported from the regulating tank to the anaerobic tank through the pump (13) (14) respectively. Tanks (1) (2), intermittently open the valve (3) on the forced circulation pipe (8), through the reuse of biogas slurry at the biogas slurry port (7), reduce the demand for tap water in the process of conditioning raw materials, Thereby reducing the yield of biogas slurry in the fermentation process. 4. A kind of perishable organic matter single-two-phase anaerobic digestion device according to claim 1, is characterized in that: when adopting series mode, in order to improve digestibility tank (1) to the digestibility of high-load and high-concentration raw material , the agitation (15) in the digestion tank (1) is turned on, adopting the CSTR+UASB mode, while the digestion tank (2) adopts the UASB mode; Both (2) and (2) adopt UASB mode. 5. a kind of perishable organic matter single-two-phase anaerobic digestion device according to claim 1, is characterized in that: the raw material that enters anaerobic digestion tank (1) (2) enters the bottom of the tank via distributor (17), The distributor ensures the even distribution of raw materials in the bottom of the tank. 6. A kind of perishable organic matter single-two-phase anaerobic digestion device according to claim 1, is characterized in that: anaerobic digestion tank (1) (2) all links to each other with regulating tank by forced return pipe (8), The use of the forced reflux pipe ensures the consistency of the fermentation characteristics of the two anaerobic digestion tanks in parallel operation. 7. A single-two-phase anaerobic digestion device for perishable organic matter according to claim 1, characterized in that: the distributor (17) is connected to the gas storage tank, and the biogas in the gas storage tank is opened every 2 days to distribute the material. The device is purged for 60 minutes to avoid blockage caused by material deposition in the distributor and affect the distribution of material and liquid.